stlink: Add PID for V3 device without MSD
[fw/openocd] / src / jtag / drivers / stlink_usb.c
index 554ffc1edcbfc2e76e6fe9fd558a3dce37f988b1..e8e2472eeeabf7559e2329ef2837d20b665a63f3 100644 (file)
@@ -1,4 +1,11 @@
 /***************************************************************************
+ *   Copyright (C) 2020 by Tarek Bochkati                                  *
+ *   Tarek Bochkati <tarek.bouchkati@gmail.com>                            *
+ *                                                                         *
+ *   SWIM contributions by Ake Rehnman                                     *
+ *   Copyright (C) 2017  Ake Rehnman                                       *
+ *   ake.rehnman(at)gmail.com                                              *
+ *                                                                         *
  *   Copyright (C) 2011-2012 by Mathias Kuester                            *
  *   Mathias Kuester <kesmtp@freenet.de>                                   *
  *                                                                         *
@@ -18,9 +25,7 @@
  *   GNU General Public License for more details.                          *
  *                                                                         *
  *   You should have received a copy of the GNU General Public License     *
- *   along with this program; if not, write to the                         *
- *   Free Software Foundation, Inc.,                                       *
- *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.           *
+ *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
  ***************************************************************************/
 
 #ifdef HAVE_CONFIG_H
 
 /* project specific includes */
 #include <helper/binarybuffer.h>
+#include <helper/bits.h>
+#include <helper/system.h>
 #include <jtag/interface.h>
 #include <jtag/hla/hla_layout.h>
 #include <jtag/hla/hla_transport.h>
 #include <jtag/hla/hla_interface.h>
+#include <jtag/swim.h>
 #include <target/target.h>
+#include <transport/transport.h>
 
 #include <target/cortex_m.h>
 
-#include "libusb_common.h"
+#include <helper/system.h>
+
+#ifdef HAVE_ARPA_INET_H
+#include <arpa/inet.h>
+#endif
+
+#ifdef HAVE_NETINET_TCP_H
+#include <netinet/tcp.h>
+#endif
+
+#include "libusb_helper.h"
+
+#ifdef HAVE_LIBUSB1
+#define USE_LIBUSB_ASYNCIO
+#endif
+
+#define STLINK_SERIAL_LEN 24
 
 #define ENDPOINT_IN  0x80
 #define ENDPOINT_OUT 0x00
@@ -45,7 +70,6 @@
 #define STLINK_WRITE_TIMEOUT 1000
 #define STLINK_READ_TIMEOUT 1000
 
-#define STLINK_NULL_EP        0
 #define STLINK_RX_EP          (1|ENDPOINT_IN)
 #define STLINK_TX_EP          (2|ENDPOINT_OUT)
 #define STLINK_TRACE_EP       (3|ENDPOINT_IN)
 #define STLINK_V1_PID         (0x3744)
 #define STLINK_V2_PID         (0x3748)
 #define STLINK_V2_1_PID       (0x374B)
-
-/* the current implementation of the stlink limits
- * 8bit read/writes to max 64 bytes. */
+#define STLINK_V2_1_NO_MSD_PID  (0x3752)
+#define STLINK_V3_USBLOADER_PID (0x374D)
+#define STLINK_V3E_PID          (0x374E)
+#define STLINK_V3S_PID          (0x374F)
+#define STLINK_V3_2VCP_PID      (0x3753)
+#define STLINK_V3E_NO_MSD_PID   (0x3754)
+
+/*
+ * ST-Link/V1, ST-Link/V2 and ST-Link/V2.1 are full-speed USB devices and
+ * this limits the bulk packet size and the 8bit read/writes to max 64 bytes.
+ * STLINK-V3 is a high speed USB 2.0 and the limit is 512 bytes from FW V3J6.
+ */
 #define STLINK_MAX_RW8         (64)
+#define STLINKV3_MAX_RW8       (512)
 
 /* "WAIT" responses will be retried (with exponential backoff) at
  * most this many times before failing to caller.
 enum stlink_jtag_api_version {
        STLINK_JTAG_API_V1 = 1,
        STLINK_JTAG_API_V2,
+       STLINK_JTAG_API_V3,
+};
+
+enum stlink_mode {
+       STLINK_MODE_UNKNOWN = 0,
+       STLINK_MODE_DFU,
+       STLINK_MODE_MASS,
+       STLINK_MODE_DEBUG_JTAG,
+       STLINK_MODE_DEBUG_SWD,
+       STLINK_MODE_DEBUG_SWIM
 };
 
 /** */
@@ -84,16 +128,54 @@ struct stlink_usb_version {
        int jtag;
        /** */
        int swim;
-       /** highest supported jtag api version */
-       enum stlink_jtag_api_version jtag_api_max;
+       /** jtag api version supported */
+       enum stlink_jtag_api_version jtag_api;
+       /** one bit for each feature supported. See macros STLINK_F_* */
+       uint32_t flags;
+};
+
+struct stlink_usb_priv_s {
+       /** */
+       struct libusb_device_handle *fd;
+       /** */
+       struct libusb_transfer *trans;
+};
+
+struct stlink_tcp_priv_s {
+       /** */
+       int fd;
+       /** */
+       bool connected;
+       /** */
+       uint32_t device_id;
+       /** */
+       uint32_t connect_id;
+       /** */
+       uint8_t *send_buf;
+       /** */
+       uint8_t *recv_buf;
+};
+
+struct stlink_backend_s {
+       /** */
+       int (*open)(void *handle, struct hl_interface_param_s *param);
+       /** */
+       int (*close)(void *handle);
+       /** */
+       int (*xfer_noerrcheck)(void *handle, const uint8_t *buf, int size);
+       /** */
+       int (*read_trace)(void *handle, const uint8_t *buf, int size);
 };
 
 /** */
 struct stlink_usb_handle_s {
        /** */
-       struct jtag_libusb_device_handle *fd;
+       struct stlink_backend_s *backend;
        /** */
-       struct libusb_transfer *trans;
+       union {
+               struct stlink_usb_priv_s usb_backend_priv;
+               struct stlink_tcp_priv_s tcp_backend_priv;
+       };
        /** */
        uint8_t rx_ep;
        /** */
@@ -101,45 +183,76 @@ struct stlink_usb_handle_s {
        /** */
        uint8_t trace_ep;
        /** */
-       uint8_t cmdbuf[STLINK_SG_SIZE];
+       uint8_t *cmdbuf;
        /** */
        uint8_t cmdidx;
        /** */
        uint8_t direction;
        /** */
-       uint8_t databuf[STLINK_DATA_SIZE];
+       uint8_t *databuf;
        /** */
        uint32_t max_mem_packet;
        /** */
-       enum hl_transports transport;
+       enum stlink_mode st_mode;
        /** */
        struct stlink_usb_version version;
        /** */
        uint16_t vid;
        /** */
        uint16_t pid;
-       /** this is the currently used jtag api */
-       enum stlink_jtag_api_version jtag_api;
        /** */
        struct {
                /** whether SWO tracing is enabled or not */
                bool enabled;
-               /** trace data destination file */
-               FILE *output_f;
-               /** trace module source clock (for prescaler) */
+               /** trace module source clock */
                uint32_t source_hz;
-               /** trace module clock prescaler */
-               uint32_t prescale;
        } trace;
        /** reconnect is needed next time we try to query the
         * status */
        bool reconnect_pending;
 };
 
+/** */
+static inline int stlink_usb_open(void *handle, struct hl_interface_param_s *param)
+{
+       struct stlink_usb_handle_s *h = handle;
+       return h->backend->open(handle, param);
+}
+
+/** */
+static inline int stlink_usb_close(void *handle)
+{
+       struct stlink_usb_handle_s *h = handle;
+       return h->backend->close(handle);
+}
+/** */
+static inline int stlink_usb_xfer_noerrcheck(void *handle, const uint8_t *buf, int size)
+{
+       struct stlink_usb_handle_s *h = handle;
+       return h->backend->xfer_noerrcheck(handle, buf, size);
+}
+
+#define STLINK_SWIM_ERR_OK             0x00
+#define STLINK_SWIM_BUSY               0x01
 #define STLINK_DEBUG_ERR_OK            0x80
 #define STLINK_DEBUG_ERR_FAULT         0x81
 #define STLINK_SWD_AP_WAIT             0x10
+#define STLINK_SWD_AP_FAULT            0x11
+#define STLINK_SWD_AP_ERROR            0x12
+#define STLINK_SWD_AP_PARITY_ERROR     0x13
+#define STLINK_JTAG_GET_IDCODE_ERROR   0x09
+#define STLINK_JTAG_WRITE_ERROR        0x0c
+#define STLINK_JTAG_WRITE_VERIF_ERROR  0x0d
 #define STLINK_SWD_DP_WAIT             0x14
+#define STLINK_SWD_DP_FAULT            0x15
+#define STLINK_SWD_DP_ERROR            0x16
+#define STLINK_SWD_DP_PARITY_ERROR     0x17
+
+#define STLINK_SWD_AP_WDATA_ERROR      0x18
+#define STLINK_SWD_AP_STICKY_ERROR     0x19
+#define STLINK_SWD_AP_STICKYORUN_ERROR 0x1a
+
+#define STLINK_BAD_AP_ERROR            0x1d
 
 #define STLINK_CORE_RUNNING            0x80
 #define STLINK_CORE_HALTED             0x81
@@ -161,10 +274,37 @@ struct stlink_usb_handle_s {
 
 #define STLINK_DFU_EXIT                0x07
 
-#define STLINK_SWIM_ENTER              0x00
-#define STLINK_SWIM_EXIT               0x01
+/*
+       STLINK_SWIM_ENTER_SEQ
+       1.3ms low then 750Hz then 1.5kHz
+
+       STLINK_SWIM_GEN_RST
+       STM8 DM pulls reset pin low 50us
+
+       STLINK_SWIM_SPEED
+       uint8_t (0=low|1=high)
+
+       STLINK_SWIM_WRITEMEM
+       uint16_t length
+       uint32_t address
+
+       STLINK_SWIM_RESET
+       send synchronization seq (16us low, response 64 clocks low)
+*/
+#define STLINK_SWIM_ENTER                  0x00
+#define STLINK_SWIM_EXIT                   0x01
+#define STLINK_SWIM_READ_CAP               0x02
+#define STLINK_SWIM_SPEED                  0x03
+#define STLINK_SWIM_ENTER_SEQ              0x04
+#define STLINK_SWIM_GEN_RST                0x05
+#define STLINK_SWIM_RESET                  0x06
+#define STLINK_SWIM_ASSERT_RESET           0x07
+#define STLINK_SWIM_DEASSERT_RESET         0x08
+#define STLINK_SWIM_READSTATUS             0x09
+#define STLINK_SWIM_WRITEMEM               0x0a
+#define STLINK_SWIM_READMEM                0x0b
+#define STLINK_SWIM_READBUF                0x0c
 
-#define STLINK_DEBUG_ENTER_JTAG            0x00
 #define STLINK_DEBUG_GETSTATUS             0x01
 #define STLINK_DEBUG_FORCEDEBUG            0x02
 #define STLINK_DEBUG_APIV1_RESETSYS        0x03
@@ -182,8 +322,9 @@ struct stlink_usb_handle_s {
 #define STLINK_DEBUG_APIV1_WRITEDEBUGREG   0x0f
 #define STLINK_DEBUG_APIV1_SETWATCHPOINT   0x10
 
-#define STLINK_DEBUG_ENTER_JTAG            0x00
-#define STLINK_DEBUG_ENTER_SWD             0xa3
+#define STLINK_DEBUG_ENTER_JTAG_RESET      0x00
+#define STLINK_DEBUG_ENTER_SWD_NO_RESET    0xa3
+#define STLINK_DEBUG_ENTER_JTAG_NO_RESET   0xa4
 
 #define STLINK_DEBUG_APIV1_ENTER           0x20
 #define STLINK_DEBUG_EXIT                  0x21
@@ -201,36 +342,103 @@ struct stlink_usb_handle_s {
 #define STLINK_DEBUG_APIV2_GETLASTRWSTATUS 0x3B
 #define STLINK_DEBUG_APIV2_DRIVE_NRST      0x3C
 
+#define STLINK_DEBUG_APIV2_GETLASTRWSTATUS2 0x3E
+
 #define STLINK_DEBUG_APIV2_START_TRACE_RX  0x40
 #define STLINK_DEBUG_APIV2_STOP_TRACE_RX   0x41
 #define STLINK_DEBUG_APIV2_GET_TRACE_NB    0x42
 #define STLINK_DEBUG_APIV2_SWD_SET_FREQ    0x43
+#define STLINK_DEBUG_APIV2_JTAG_SET_FREQ   0x44
+#define STLINK_DEBUG_APIV2_READ_DAP_REG    0x45
+#define STLINK_DEBUG_APIV2_WRITE_DAP_REG   0x46
+#define STLINK_DEBUG_APIV2_READMEM_16BIT   0x47
+#define STLINK_DEBUG_APIV2_WRITEMEM_16BIT  0x48
+
+#define STLINK_DEBUG_APIV2_INIT_AP         0x4B
+#define STLINK_DEBUG_APIV2_CLOSE_AP_DBG    0x4C
+
+#define STLINK_APIV3_SET_COM_FREQ           0x61
+#define STLINK_APIV3_GET_COM_FREQ           0x62
+
+#define STLINK_APIV3_GET_VERSION_EX         0xFB
 
 #define STLINK_DEBUG_APIV2_DRIVE_NRST_LOW   0x00
 #define STLINK_DEBUG_APIV2_DRIVE_NRST_HIGH  0x01
 #define STLINK_DEBUG_APIV2_DRIVE_NRST_PULSE 0x02
 
-#define STLINK_TRACE_SIZE               1024
+#define STLINK_DEBUG_PORT_ACCESS            0xffff
+
+#define STLINK_TRACE_SIZE               4096
 #define STLINK_TRACE_MAX_HZ             2000000
-#define STLINK_TRACE_MIN_VERSION        13
+#define STLINK_V3_TRACE_MAX_HZ          24000000
 
-/** */
-enum stlink_mode {
-       STLINK_MODE_UNKNOWN = 0,
-       STLINK_MODE_DFU,
-       STLINK_MODE_MASS,
-       STLINK_MODE_DEBUG_JTAG,
-       STLINK_MODE_DEBUG_SWD,
-       STLINK_MODE_DEBUG_SWIM
-};
+#define STLINK_V3_MAX_FREQ_NB               10
 
 #define REQUEST_SENSE        0x03
 #define REQUEST_SENSE_LENGTH 18
 
-static const struct {
+/* STLINK TCP commands */
+#define STLINK_TCP_CMD_REFRESH_DEVICE_LIST   0x00
+#define STLINK_TCP_CMD_GET_NB_DEV            0x01
+#define STLINK_TCP_CMD_GET_DEV_INFO          0x02
+#define STLINK_TCP_CMD_OPEN_DEV              0x03
+#define STLINK_TCP_CMD_CLOSE_DEV             0x04
+#define STLINK_TCP_CMD_SEND_USB_CMD          0x05
+#define STLINK_TCP_CMD_GET_SERVER_VERSION    0x06
+#define STLINK_TCP_CMD_GET_NB_OF_DEV_CLIENTS 0x07
+
+/* STLINK TCP constants */
+#define OPENOCD_STLINK_TCP_API_VERSION       1
+#define STLINK_TCP_REQUEST_WRITE             0
+#define STLINK_TCP_REQUEST_READ              1
+#define STLINK_TCP_REQUEST_READ_SWO          3
+#define STLINK_TCP_SS_SIZE                   4
+#define STLINK_TCP_USB_CMD_SIZE              32
+#define STLINK_TCP_SERIAL_SIZE               32
+#define STLINK_TCP_SEND_BUFFER_SIZE          10240
+#define STLINK_TCP_RECV_BUFFER_SIZE          10240
+
+/* STLINK TCP command status */
+#define STLINK_TCP_SS_OK                     0x00000001
+#define STLINK_TCP_SS_MEMORY_PROBLEM         0x00001000
+#define STLINK_TCP_SS_TIMEOUT                0x00001001
+#define STLINK_TCP_SS_BAD_PARAMETER          0x00001002
+#define STLINK_TCP_SS_OPEN_ERR               0x00001003
+#define STLINK_TCP_SS_TRUNCATED_DATA         0x00001052
+#define STLINK_TCP_SS_CMD_NOT_AVAILABLE      0x00001053
+#define STLINK_TCP_SS_TCP_ERROR              0x00002001
+#define STLINK_TCP_SS_TCP_CANT_CONNECT       0x00002002
+#define STLINK_TCP_SS_WIN32_ERROR            0x00010000
+
+/*
+ * Map the relevant features, quirks and workaround for specific firmware
+ * version of stlink
+ */
+#define STLINK_F_HAS_TRACE              BIT(0)  /* v2>=j13 || v3     */
+#define STLINK_F_HAS_GETLASTRWSTATUS2   BIT(1)  /* v2>=j15 || v3     */
+#define STLINK_F_HAS_SWD_SET_FREQ       BIT(2)  /* v2>=j22           */
+#define STLINK_F_HAS_JTAG_SET_FREQ      BIT(3)  /* v2>=j24           */
+#define STLINK_F_QUIRK_JTAG_DP_READ     BIT(4)  /* v2>=j24 && v2<j32 */
+#define STLINK_F_HAS_DAP_REG            BIT(5)  /* v2>=j24 || v3     */
+#define STLINK_F_HAS_MEM_16BIT          BIT(6)  /* v2>=j26 || v3     */
+#define STLINK_F_HAS_AP_INIT            BIT(7)  /* v2>=j28 || v3     */
+#define STLINK_F_FIX_CLOSE_AP           BIT(8)  /* v2>=j29 || v3     */
+#define STLINK_F_HAS_DPBANKSEL          BIT(9)  /* v2>=j32 || v3>=j2 */
+#define STLINK_F_HAS_RW8_512BYTES       BIT(10) /*            v3>=j6 */
+
+/* aliases */
+#define STLINK_F_HAS_TARGET_VOLT        STLINK_F_HAS_TRACE
+#define STLINK_F_HAS_FPU_REG            STLINK_F_HAS_GETLASTRWSTATUS2
+
+#define STLINK_REGSEL_IS_FPU(x)         ((x) > 0x1F)
+
+struct speed_map {
        int speed;
        int speed_divisor;
-} stlink_khz_to_speed_map[] = {
+};
+
+/* SWD clock speed */
+static const struct speed_map stlink_khz_to_speed_map_swd[] = {
        {4000, 0},
        {1800, 1}, /* default */
        {1200, 2},
@@ -245,20 +453,198 @@ static const struct {
        {5,  798}
 };
 
+/* JTAG clock speed */
+static const struct speed_map stlink_khz_to_speed_map_jtag[] = {
+       {9000,  4},
+       {4500,  8},
+       {2250, 16},
+       {1125, 32}, /* default */
+       {562,  64},
+       {281, 128},
+       {140, 256}
+};
+
 static void stlink_usb_init_buffer(void *handle, uint8_t direction, uint32_t size);
+static int stlink_swim_status(void *handle);
+static void stlink_dump_speed_map(const struct speed_map *map, unsigned int map_size);
+static int stlink_get_com_freq(void *handle, bool is_jtag, struct speed_map *map);
+static int stlink_speed(void *handle, int khz, bool query);
+static int stlink_usb_open_ap(void *handle, unsigned short apsel);
+
+/** */
+static unsigned int stlink_usb_block(void *handle)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       assert(handle);
+
+       if (h->version.flags & STLINK_F_HAS_RW8_512BYTES)
+               return STLINKV3_MAX_RW8;
+       else
+               return STLINK_MAX_RW8;
+}
+
+#ifdef USE_LIBUSB_ASYNCIO
+
+static LIBUSB_CALL void sync_transfer_cb(struct libusb_transfer *transfer)
+{
+       int *completed = transfer->user_data;
+       *completed = 1;
+       /* caller interprets result and frees transfer */
+}
+
+
+static void sync_transfer_wait_for_completion(struct libusb_transfer *transfer)
+{
+       int r, *completed = transfer->user_data;
+
+       while (!*completed) {
+               r = jtag_libusb_handle_events_completed(completed);
+               if (r < 0) {
+                       if (r == LIBUSB_ERROR_INTERRUPTED)
+                               continue;
+                       libusb_cancel_transfer(transfer);
+                       continue;
+               }
+       }
+}
+
+
+static int transfer_error_status(const struct libusb_transfer *transfer)
+{
+       int r = 0;
+
+       switch (transfer->status) {
+               case LIBUSB_TRANSFER_COMPLETED:
+                       r = 0;
+                       break;
+               case LIBUSB_TRANSFER_TIMED_OUT:
+                       r = LIBUSB_ERROR_TIMEOUT;
+                       break;
+               case LIBUSB_TRANSFER_STALL:
+                       r = LIBUSB_ERROR_PIPE;
+                       break;
+               case LIBUSB_TRANSFER_OVERFLOW:
+                       r = LIBUSB_ERROR_OVERFLOW;
+                       break;
+               case LIBUSB_TRANSFER_NO_DEVICE:
+                       r = LIBUSB_ERROR_NO_DEVICE;
+                       break;
+               case LIBUSB_TRANSFER_ERROR:
+               case LIBUSB_TRANSFER_CANCELLED:
+                       r = LIBUSB_ERROR_IO;
+                       break;
+               default:
+                       r = LIBUSB_ERROR_OTHER;
+                       break;
+       }
+
+       return r;
+}
+
+struct jtag_xfer {
+       int ep;
+       uint8_t *buf;
+       size_t size;
+       /* Internal */
+       int retval;
+       int completed;
+       size_t transfer_size;
+       struct libusb_transfer *transfer;
+};
+
+static int jtag_libusb_bulk_transfer_n(
+               struct libusb_device_handle *dev_handle,
+               struct jtag_xfer *transfers,
+               size_t n_transfers,
+               int timeout)
+{
+       int retval = 0;
+       int returnval = ERROR_OK;
+
+
+       for (size_t i = 0; i < n_transfers; ++i) {
+               transfers[i].retval = 0;
+               transfers[i].completed = 0;
+               transfers[i].transfer_size = 0;
+               transfers[i].transfer = libusb_alloc_transfer(0);
+
+               if (!transfers[i].transfer) {
+                       for (size_t j = 0; j < i; ++j)
+                               libusb_free_transfer(transfers[j].transfer);
+
+                       LOG_DEBUG("ERROR, failed to alloc usb transfers");
+                       for (size_t k = 0; k < n_transfers; ++k)
+                               transfers[k].retval = LIBUSB_ERROR_NO_MEM;
+                       return ERROR_FAIL;
+               }
+       }
+
+       for (size_t i = 0; i < n_transfers; ++i) {
+               libusb_fill_bulk_transfer(
+                               transfers[i].transfer,
+                               dev_handle,
+                               transfers[i].ep, transfers[i].buf, transfers[i].size,
+                               sync_transfer_cb, &transfers[i].completed, timeout);
+               transfers[i].transfer->type = LIBUSB_TRANSFER_TYPE_BULK;
+
+               retval = libusb_submit_transfer(transfers[i].transfer);
+               if (retval < 0) {
+                       LOG_DEBUG("ERROR, failed to submit transfer %zu, error %d", i, retval);
+
+                       /* Probably no point continuing to submit transfers once a submission fails.
+                        * As a result, tag all remaining transfers as errors.
+                        */
+                       for (size_t j = i; j < n_transfers; ++j)
+                               transfers[j].retval = retval;
+
+                       returnval = ERROR_FAIL;
+                       break;
+               }
+       }
+
+       /* Wait for every submitted USB transfer to complete.
+       */
+       for (size_t i = 0; i < n_transfers; ++i) {
+               if (transfers[i].retval == 0) {
+                       sync_transfer_wait_for_completion(transfers[i].transfer);
+
+                       retval = transfer_error_status(transfers[i].transfer);
+                       if (retval) {
+                               returnval = ERROR_FAIL;
+                               transfers[i].retval = retval;
+                               LOG_DEBUG("ERROR, transfer %zu failed, error %d", i, retval);
+                       } else {
+                               /* Assuming actual_length is only valid if there is no transfer error.
+                                */
+                               transfers[i].transfer_size = transfers[i].transfer->actual_length;
+                       }
+               }
+
+               libusb_free_transfer(transfers[i].transfer);
+               transfers[i].transfer = NULL;
+       }
+
+       return returnval;
+}
+
+#endif
+
 
 /** */
 static int stlink_usb_xfer_v1_get_status(void *handle)
 {
        struct stlink_usb_handle_s *h = handle;
+       int tr, ret;
 
-       assert(handle != NULL);
+       assert(handle);
 
        /* read status */
        memset(h->cmdbuf, 0, STLINK_SG_SIZE);
 
-       if (jtag_libusb_bulk_read(h->fd, h->rx_ep, (char *)h->cmdbuf,
-                       13, STLINK_READ_TIMEOUT) != 13)
+       ret = jtag_libusb_bulk_read(h->usb_backend_priv.fd, h->rx_ep, (char *)h->cmdbuf, 13,
+                                   STLINK_READ_TIMEOUT, &tr);
+       if (ret || tr != 13)
                return ERROR_FAIL;
 
        uint32_t t1;
@@ -280,27 +666,68 @@ static int stlink_usb_xfer_v1_get_status(void *handle)
        return ERROR_OK;
 }
 
-/** */
+#ifdef USE_LIBUSB_ASYNCIO
 static int stlink_usb_xfer_rw(void *handle, int cmdsize, const uint8_t *buf, int size)
 {
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       if (jtag_libusb_bulk_write(h->fd, h->tx_ep, (char *)h->cmdbuf, cmdsize,
-                       STLINK_WRITE_TIMEOUT) != cmdsize) {
-               return ERROR_FAIL;
+       size_t n_transfers = 0;
+       struct jtag_xfer transfers[2];
+
+       memset(transfers, 0, sizeof(transfers));
+
+       transfers[0].ep = h->tx_ep;
+       transfers[0].buf = h->cmdbuf;
+       transfers[0].size = cmdsize;
+
+       ++n_transfers;
+
+       if (h->direction == h->tx_ep && size) {
+               transfers[1].ep = h->tx_ep;
+               transfers[1].buf = (uint8_t *)buf;
+               transfers[1].size = size;
+
+               ++n_transfers;
+       } else if (h->direction == h->rx_ep && size) {
+               transfers[1].ep = h->rx_ep;
+               transfers[1].buf = (uint8_t *)buf;
+               transfers[1].size = size;
+
+               ++n_transfers;
        }
 
+       return jtag_libusb_bulk_transfer_n(
+                       h->usb_backend_priv.fd,
+                       transfers,
+                       n_transfers,
+                       STLINK_WRITE_TIMEOUT);
+}
+#else
+static int stlink_usb_xfer_rw(void *handle, int cmdsize, const uint8_t *buf, int size)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int tr, ret;
+
+       assert(handle);
+
+       ret = jtag_libusb_bulk_write(h->usb_backend_priv.fd, h->tx_ep, (char *)h->cmdbuf,
+                                    cmdsize, STLINK_WRITE_TIMEOUT, &tr);
+       if (ret || tr != cmdsize)
+               return ERROR_FAIL;
+
        if (h->direction == h->tx_ep && size) {
-               if (jtag_libusb_bulk_write(h->fd, h->tx_ep, (char *)buf,
-                               size, STLINK_WRITE_TIMEOUT) != size) {
+               ret = jtag_libusb_bulk_write(h->usb_backend_priv.fd, h->tx_ep, (char *)buf,
+                                            size, STLINK_WRITE_TIMEOUT, &tr);
+               if (ret || tr != size) {
                        LOG_DEBUG("bulk write failed");
                        return ERROR_FAIL;
                }
        } else if (h->direction == h->rx_ep && size) {
-               if (jtag_libusb_bulk_read(h->fd, h->rx_ep, (char *)buf,
-                               size, STLINK_READ_TIMEOUT) != size) {
+               ret = jtag_libusb_bulk_read(h->usb_backend_priv.fd, h->rx_ep, (char *)buf,
+                                           size, STLINK_READ_TIMEOUT, &tr);
+               if (ret || tr != size) {
                        LOG_DEBUG("bulk read failed");
                        return ERROR_FAIL;
                }
@@ -308,6 +735,7 @@ static int stlink_usb_xfer_rw(void *handle, int cmdsize, const uint8_t *buf, int
 
        return ERROR_OK;
 }
+#endif
 
 /** */
 static int stlink_usb_xfer_v1_get_sense(void *handle)
@@ -315,7 +743,7 @@ static int stlink_usb_xfer_v1_get_sense(void *handle)
        int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
        stlink_usb_init_buffer(handle, h->rx_ep, 16);
 
@@ -337,15 +765,39 @@ static int stlink_usb_xfer_v1_get_sense(void *handle)
 }
 
 /** */
-static int stlink_usb_xfer(void *handle, const uint8_t *buf, int size)
+static int stlink_usb_usb_read_trace(void *handle, const uint8_t *buf, int size)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int tr, ret;
+
+       ret = jtag_libusb_bulk_read(h->usb_backend_priv.fd, h->trace_ep, (char *)buf, size,
+                                   STLINK_READ_TIMEOUT, &tr);
+       if (ret || tr != size) {
+               LOG_ERROR("bulk trace read failed");
+               return ERROR_FAIL;
+       }
+
+       return ERROR_OK;
+}
+
+/*
+       transfers block in cmdbuf
+       <size> indicates number of bytes in the following
+       data phase.
+       Ignore the (eventual) error code in the received packet.
+*/
+static int stlink_usb_usb_xfer_noerrcheck(void *handle, const uint8_t *buf, int size)
 {
        int err, cmdsize = STLINK_CMD_SIZE_V2;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       if (h->version.stlink == 1)
+       if (h->version.stlink == 1) {
                cmdsize = STLINK_SG_SIZE;
+               /* put length in bCBWCBLength */
+               h->cmdbuf[14] = h->cmdidx-15;
+       }
 
        err = stlink_usb_xfer_rw(handle, cmdsize, buf, size);
 
@@ -368,6 +820,116 @@ static int stlink_usb_xfer(void *handle, const uint8_t *buf, int size)
 }
 
 
+static int stlink_tcp_send_cmd(void *handle, int send_size, int recv_size, bool check_tcp_status)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       assert(handle);
+
+       /* send the TCP command */
+       int sent_size = send(h->tcp_backend_priv.fd, (void *)h->tcp_backend_priv.send_buf, send_size, 0);
+       if (sent_size != send_size) {
+               LOG_ERROR("failed to send USB CMD");
+               if (sent_size == -1)
+                       LOG_DEBUG("socket send error: %s (errno %d)", strerror(errno), errno);
+               else
+                       LOG_DEBUG("sent size %d (expected %d)", sent_size, send_size);
+               return ERROR_FAIL;
+       }
+
+       keep_alive();
+
+       /* read the TCP response */
+       int received_size = recv(h->tcp_backend_priv.fd, (void *)h->tcp_backend_priv.recv_buf, recv_size, 0);
+       if (received_size != recv_size) {
+               LOG_ERROR("failed to receive USB CMD response");
+               if (received_size == -1)
+                       LOG_DEBUG("socket recv error: %s (errno %d)", strerror(errno), errno);
+               else
+                       LOG_DEBUG("received size %d (expected %d)", received_size, recv_size);
+               return ERROR_FAIL;
+       }
+
+       if (check_tcp_status) {
+               uint32_t tcp_ss = le_to_h_u32(h->tcp_backend_priv.recv_buf);
+               if (tcp_ss != STLINK_TCP_SS_OK) {
+                       LOG_ERROR("TCP error status 0x%X", tcp_ss);
+                       return ERROR_FAIL;
+               }
+       }
+
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_tcp_xfer_noerrcheck(void *handle, const uint8_t *buf, int size)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       int send_size = STLINK_TCP_USB_CMD_SIZE;
+       int recv_size = STLINK_TCP_SS_SIZE;
+
+       assert(handle);
+
+       /* prepare the TCP command */
+       h->tcp_backend_priv.send_buf[0] = STLINK_TCP_CMD_SEND_USB_CMD;
+       memset(&h->tcp_backend_priv.send_buf[1], 0, 3); /* reserved for alignment and future use, must be zero */
+       h_u32_to_le(&h->tcp_backend_priv.send_buf[4], h->tcp_backend_priv.connect_id);
+       /* tcp_backend_priv.send_buf[8..23] already contains the constructed stlink command */
+       h->tcp_backend_priv.send_buf[24] = h->direction;
+       memset(&h->tcp_backend_priv.send_buf[25], 0, 3);  /* reserved for alignment and future use, must be zero */
+
+       h_u32_to_le(&h->tcp_backend_priv.send_buf[28], size);
+
+       /*
+        * if the xfer is a write request (tx_ep)
+        *  > then buf content will be copied
+        * into &cmdbuf[32].
+        * else : the xfer is a read or trace read request (rx_ep or trace_ep)
+        *  > the buf content will be filled from &databuf[4].
+        *
+        * note : if h->direction is trace_ep, h->cmdbuf is zeros.
+        */
+
+       if (h->direction == h->tx_ep) { /* STLINK_TCP_REQUEST_WRITE */
+               send_size += size;
+               if (send_size > STLINK_TCP_SEND_BUFFER_SIZE) {
+                       LOG_ERROR("STLINK_TCP command buffer overflow");
+                       return ERROR_FAIL;
+               }
+               memcpy(&h->tcp_backend_priv.send_buf[32], buf, size);
+       } else { /* STLINK_TCP_REQUEST_READ or STLINK_TCP_REQUEST_READ_SWO */
+               recv_size += size;
+               if (recv_size > STLINK_TCP_RECV_BUFFER_SIZE) {
+                       LOG_ERROR("STLINK_TCP data buffer overflow");
+                       return ERROR_FAIL;
+               }
+       }
+
+       int ret = stlink_tcp_send_cmd(h, send_size, recv_size, true);
+       if (ret != ERROR_OK)
+               return ret;
+
+       if (h->direction != h->tx_ep) {
+               /* the read data is located in tcp_backend_priv.recv_buf[4] */
+               /* most of the case it will be copying the data from tcp_backend_priv.recv_buf[4]
+                * to handle->cmd_buff which are the same, so let's avoid unnecessary copying */
+               if (buf != &h->tcp_backend_priv.recv_buf[4])
+                       memcpy((uint8_t *)buf, &h->tcp_backend_priv.recv_buf[4], size);
+       }
+
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_tcp_read_trace(void *handle, const uint8_t *buf, int size)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       stlink_usb_init_buffer(h, h->trace_ep, 0);
+       return stlink_tcp_xfer_noerrcheck(handle, buf, size);
+}
+
 /**
     Converts an STLINK status code held in the first byte of a response
     to an openocd error, logs any error/wait status as debug output.
@@ -376,10 +938,22 @@ static int stlink_usb_error_check(void *handle)
 {
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
+
+       if (h->st_mode == STLINK_MODE_DEBUG_SWIM) {
+               switch (h->databuf[0]) {
+                       case STLINK_SWIM_ERR_OK:
+                               return ERROR_OK;
+                       case STLINK_SWIM_BUSY:
+                               return ERROR_WAIT;
+                       default:
+                               LOG_DEBUG("unknown/unexpected STLINK status code 0x%x", h->databuf[0]);
+                               return ERROR_FAIL;
+               }
+       }
 
        /* TODO: no error checking yet on api V1 */
-       if (h->jtag_api == STLINK_JTAG_API_V1)
+       if (h->version.jtag_api == STLINK_JTAG_API_V1)
                h->databuf[0] = STLINK_DEBUG_ERR_OK;
 
        switch (h->databuf[0]) {
@@ -392,19 +966,79 @@ static int stlink_usb_error_check(void *handle)
                        LOG_DEBUG("wait status SWD_AP_WAIT (0x%x)", STLINK_SWD_AP_WAIT);
                        return ERROR_WAIT;
                case STLINK_SWD_DP_WAIT:
-                       LOG_DEBUG("wait status SWD_DP_WAIT (0x%x)", STLINK_SWD_AP_WAIT);
+                       LOG_DEBUG("wait status SWD_DP_WAIT (0x%x)", STLINK_SWD_DP_WAIT);
                        return ERROR_WAIT;
+               case STLINK_JTAG_GET_IDCODE_ERROR:
+                       LOG_DEBUG("STLINK_JTAG_GET_IDCODE_ERROR");
+                       return ERROR_FAIL;
+               case STLINK_JTAG_WRITE_ERROR:
+                       LOG_DEBUG("Write error");
+                       return ERROR_FAIL;
+               case STLINK_JTAG_WRITE_VERIF_ERROR:
+                       LOG_DEBUG("Write verify error, ignoring");
+                       return ERROR_OK;
+               case STLINK_SWD_AP_FAULT:
+                       /* git://git.ac6.fr/openocd commit 657e3e885b9ee10
+                        * returns ERROR_OK with the comment:
+                        * Change in error status when reading outside RAM.
+                        * This fix allows CDT plugin to visualize memory.
+                        */
+                       LOG_DEBUG("STLINK_SWD_AP_FAULT");
+                       return ERROR_FAIL;
+               case STLINK_SWD_AP_ERROR:
+                       LOG_DEBUG("STLINK_SWD_AP_ERROR");
+                       return ERROR_FAIL;
+               case STLINK_SWD_AP_PARITY_ERROR:
+                       LOG_DEBUG("STLINK_SWD_AP_PARITY_ERROR");
+                       return ERROR_FAIL;
+               case STLINK_SWD_DP_FAULT:
+                       LOG_DEBUG("STLINK_SWD_DP_FAULT");
+                       return ERROR_FAIL;
+               case STLINK_SWD_DP_ERROR:
+                       LOG_DEBUG("STLINK_SWD_DP_ERROR");
+                       return ERROR_FAIL;
+               case STLINK_SWD_DP_PARITY_ERROR:
+                       LOG_DEBUG("STLINK_SWD_DP_PARITY_ERROR");
+                       return ERROR_FAIL;
+               case STLINK_SWD_AP_WDATA_ERROR:
+                       LOG_DEBUG("STLINK_SWD_AP_WDATA_ERROR");
+                       return ERROR_FAIL;
+               case STLINK_SWD_AP_STICKY_ERROR:
+                       LOG_DEBUG("STLINK_SWD_AP_STICKY_ERROR");
+                       return ERROR_FAIL;
+               case STLINK_SWD_AP_STICKYORUN_ERROR:
+                       LOG_DEBUG("STLINK_SWD_AP_STICKYORUN_ERROR");
+                       return ERROR_FAIL;
+               case STLINK_BAD_AP_ERROR:
+                       LOG_DEBUG("STLINK_BAD_AP_ERROR");
+                       return ERROR_FAIL;
                default:
                        LOG_DEBUG("unknown/unexpected STLINK status code 0x%x", h->databuf[0]);
                        return ERROR_FAIL;
        }
 }
 
+/*
+ * Wrapper around stlink_usb_xfer_noerrcheck()
+ * to check the error code in the received packet
+ */
+static int stlink_usb_xfer_errcheck(void *handle, const uint8_t *buf, int size)
+{
+       int retval;
+
+       assert(size > 0);
+
+       retval = stlink_usb_xfer_noerrcheck(handle, buf, size);
+       if (retval != ERROR_OK)
+               return retval;
+
+       return stlink_usb_error_check(handle);
+}
 
 /** Issue an STLINK command via USB transfer, with retries on any wait status responses.
 
     Works for commands where the STLINK_DEBUG status is returned in the first
-    byte of the response packet.
+    byte of the response packet. For SWIM a SWIM_READSTATUS is requested instead.
 
     Returns an openocd result code.
 */
@@ -412,13 +1046,26 @@ static int stlink_cmd_allow_retry(void *handle, const uint8_t *buf, int size)
 {
        int retries = 0;
        int res;
+       struct stlink_usb_handle_s *h = handle;
+
        while (1) {
-               res = stlink_usb_xfer(handle, buf, size);
-               if (res != ERROR_OK)
-                       return res;
-               res = stlink_usb_error_check(handle);
-               if (res == ERROR_WAIT && retries < MAX_WAIT_RETRIES) {
-                       usleep((1<<retries++) * 1000);
+               if ((h->st_mode != STLINK_MODE_DEBUG_SWIM) || !retries) {
+                       res = stlink_usb_xfer_noerrcheck(handle, buf, size);
+                       if (res != ERROR_OK)
+                               return res;
+               }
+
+               if (h->st_mode == STLINK_MODE_DEBUG_SWIM) {
+                       res = stlink_swim_status(handle);
+                       if (res != ERROR_OK)
+                               return res;
+               }
+
+               res = stlink_usb_error_check(handle);
+               if (res == ERROR_WAIT && retries < MAX_WAIT_RETRIES) {
+                       unsigned int delay_us = (1<<retries++) * 1000;
+                       LOG_DEBUG("stlink_cmd_allow_retry ERROR_WAIT, retry %d, delaying %u microseconds", retries, delay_us);
+                       usleep(delay_us);
                        continue;
                }
                return res;
@@ -430,20 +1077,24 @@ static int stlink_usb_read_trace(void *handle, const uint8_t *buf, int size)
 {
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       assert(h->version.stlink >= 2);
+       assert(h->version.flags & STLINK_F_HAS_TRACE);
 
-       if (jtag_libusb_bulk_read(h->fd, h->trace_ep, (char *)buf,
-                       size, STLINK_READ_TIMEOUT) != size) {
-               LOG_ERROR("bulk trace read failed");
-               return ERROR_FAIL;
-       }
+       return h->backend->read_trace(handle, buf, size);
+}
 
-       return ERROR_OK;
+/*
+       this function writes transfer length in
+       the right place in the cb
+*/
+static void stlink_usb_set_cbw_transfer_datalength(void *handle, uint32_t size)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       buf_set_u32(h->cmdbuf+8, 0, 32, size);
 }
 
-/** */
 static void stlink_usb_xfer_v1_create_cmd(void *handle, uint8_t direction, uint32_t size)
 {
        struct stlink_usb_handle_s *h = handle;
@@ -452,12 +1103,16 @@ static void stlink_usb_xfer_v1_create_cmd(void *handle, uint8_t direction, uint3
        strcpy((char *)h->cmdbuf, "USBC");
        h->cmdidx += 4;
        /* csw tag not used */
+       buf_set_u32(h->cmdbuf+h->cmdidx, 0, 32, 0);
        h->cmdidx += 4;
+       /* cbw data transfer length (in the following data phase in or out) */
        buf_set_u32(h->cmdbuf+h->cmdidx, 0, 32, size);
        h->cmdidx += 4;
+       /* cbw flags */
        h->cmdbuf[h->cmdidx++] = (direction == h->rx_ep ? ENDPOINT_IN : ENDPOINT_OUT);
        h->cmdbuf[h->cmdidx++] = 0; /* lun */
-       h->cmdbuf[h->cmdidx++] = STLINK_CMD_SIZE_V1;
+       /* cdb clength (is filled in at xfer) */
+       h->cmdbuf[h->cmdidx++] = 0;
 }
 
 /** */
@@ -480,41 +1135,185 @@ static void stlink_usb_init_buffer(void *handle, uint8_t direction, uint32_t siz
 static int stlink_usb_version(void *handle)
 {
        int res;
-       uint16_t v;
+       uint32_t flags;
+       uint16_t version;
+       uint8_t v, x, y, jtag, swim, msd, bridge = 0;
+       char v_str[5 * (1 + 3) + 1]; /* VvJjMmBbSs */
+       char *p;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
        stlink_usb_init_buffer(handle, h->rx_ep, 6);
 
        h->cmdbuf[h->cmdidx++] = STLINK_GET_VERSION;
 
-       res = stlink_usb_xfer(handle, h->databuf, 6);
+       res = stlink_usb_xfer_noerrcheck(handle, h->databuf, 6);
 
        if (res != ERROR_OK)
                return res;
 
-       v = (h->databuf[0] << 8) | h->databuf[1];
+       version = be_to_h_u16(h->databuf);
+       v = (version >> 12) & 0x0f;
+       x = (version >> 6) & 0x3f;
+       y = version & 0x3f;
+
+       h->vid = le_to_h_u16(h->databuf + 2);
+       h->pid = le_to_h_u16(h->databuf + 4);
+
+       switch (h->pid) {
+       case STLINK_V2_1_PID:
+       case STLINK_V2_1_NO_MSD_PID:
+               if ((x <= 22 && y == 7) || (x >= 25 && y >= 7 && y <= 12)) {
+                       /* MxSy : STM8 V2.1 - SWIM only */
+                       msd = x;
+                       swim = y;
+                       jtag = 0;
+               } else {
+                       /* JxMy : STM32 V2.1 - JTAG/SWD only */
+                       jtag = x;
+                       msd = y;
+                       swim = 0;
+               }
+               break;
+       default:
+               jtag = x;
+               swim = y;
+               msd = 0;
+               break;
+       }
 
-       h->version.stlink = (v >> 12) & 0x0f;
-       h->version.jtag = (v >> 6) & 0x3f;
-       h->version.swim = v & 0x3f;
-       h->vid = buf_get_u32(h->databuf, 16, 16);
-       h->pid = buf_get_u32(h->databuf, 32, 16);
+       /* STLINK-V3 requires a specific command */
+       if (v == 3 && x == 0 && y == 0) {
+               stlink_usb_init_buffer(handle, h->rx_ep, 16);
 
-       /* set the supported jtag api version
-        * API V2 is supported since JTAG V11
-        */
-       if (h->version.jtag >= 11)
-               h->version.jtag_api_max = STLINK_JTAG_API_V2;
-       else
-               h->version.jtag_api_max = STLINK_JTAG_API_V1;
+               h->cmdbuf[h->cmdidx++] = STLINK_APIV3_GET_VERSION_EX;
+
+               res = stlink_usb_xfer_noerrcheck(handle, h->databuf, 12);
+               if (res != ERROR_OK)
+                       return res;
+
+               v = h->databuf[0];
+               swim = h->databuf[1];
+               jtag = h->databuf[2];
+               msd  = h->databuf[3];
+               bridge = h->databuf[4];
+               h->vid = le_to_h_u16(h->databuf + 8);
+               h->pid = le_to_h_u16(h->databuf + 10);
+       }
+
+       h->version.stlink = v;
+       h->version.jtag = jtag;
+       h->version.swim = swim;
+
+       flags = 0;
+       switch (h->version.stlink) {
+       case 1:
+               /* ST-LINK/V1 from J11 switch to api-v2 (and support SWD) */
+               if (h->version.jtag >= 11)
+                       h->version.jtag_api = STLINK_JTAG_API_V2;
+               else
+                       h->version.jtag_api = STLINK_JTAG_API_V1;
+
+               break;
+       case 2:
+               /* all ST-LINK/V2 and ST-Link/V2.1 use api-v2 */
+               h->version.jtag_api = STLINK_JTAG_API_V2;
+
+               /* API for trace from J13 */
+               /* API for target voltage from J13 */
+               if (h->version.jtag >= 13)
+                       flags |= STLINK_F_HAS_TRACE;
+
+               /* preferred API to get last R/W status from J15 */
+               if (h->version.jtag >= 15)
+                       flags |= STLINK_F_HAS_GETLASTRWSTATUS2;
+
+               /* API to set SWD frequency from J22 */
+               if (h->version.jtag >= 22)
+                       flags |= STLINK_F_HAS_SWD_SET_FREQ;
+
+               /* API to set JTAG frequency from J24 */
+               /* API to access DAP registers from J24 */
+               if (h->version.jtag >= 24) {
+                       flags |= STLINK_F_HAS_JTAG_SET_FREQ;
+                       flags |= STLINK_F_HAS_DAP_REG;
+               }
+
+               /* Quirk for read DP in JTAG mode (V2 only) from J24, fixed in J32 */
+               if (h->version.jtag >= 24 && h->version.jtag < 32)
+                       flags |= STLINK_F_QUIRK_JTAG_DP_READ;
 
-       LOG_INFO("STLINK v%d JTAG v%d API v%d SWIM v%d VID 0x%04X PID 0x%04X",
-               h->version.stlink,
-               h->version.jtag,
-               (h->version.jtag_api_max == STLINK_JTAG_API_V1) ? 1 : 2,
-               h->version.swim,
+               /* API to read/write memory at 16 bit from J26 */
+               if (h->version.jtag >= 26)
+                       flags |= STLINK_F_HAS_MEM_16BIT;
+
+               /* API required to init AP before any AP access from J28 */
+               if (h->version.jtag >= 28)
+                       flags |= STLINK_F_HAS_AP_INIT;
+
+               /* API required to return proper error code on close AP from J29 */
+               if (h->version.jtag >= 29)
+                       flags |= STLINK_F_FIX_CLOSE_AP;
+
+               /* Banked regs (DPv1 & DPv2) support from V2J32 */
+               if (h->version.jtag >= 32)
+                       flags |= STLINK_F_HAS_DPBANKSEL;
+
+               break;
+       case 3:
+               /* all STLINK-V3 use api-v3 */
+               h->version.jtag_api = STLINK_JTAG_API_V3;
+
+               /* STLINK-V3 is a superset of ST-LINK/V2 */
+
+               /* API for trace */
+               /* API for target voltage */
+               flags |= STLINK_F_HAS_TRACE;
+
+               /* preferred API to get last R/W status */
+               flags |= STLINK_F_HAS_GETLASTRWSTATUS2;
+
+               /* API to access DAP registers */
+               flags |= STLINK_F_HAS_DAP_REG;
+
+               /* API to read/write memory at 16 bit */
+               flags |= STLINK_F_HAS_MEM_16BIT;
+
+               /* API required to init AP before any AP access */
+               flags |= STLINK_F_HAS_AP_INIT;
+
+               /* API required to return proper error code on close AP */
+               flags |= STLINK_F_FIX_CLOSE_AP;
+
+               /* Banked regs (DPv1 & DPv2) support from V3J2 */
+               if (h->version.jtag >= 2)
+                       flags |= STLINK_F_HAS_DPBANKSEL;
+
+               /* 8bit read/write max packet size 512 bytes from V3J6 */
+               if (h->version.jtag >= 6)
+                       flags |= STLINK_F_HAS_RW8_512BYTES;
+
+               break;
+       default:
+               break;
+       }
+       h->version.flags = flags;
+
+       p = v_str;
+       p += sprintf(p, "V%d", v);
+       if (jtag || !msd)
+               p += sprintf(p, "J%d", jtag);
+       if (msd)
+               p += sprintf(p, "M%d", msd);
+       if (bridge)
+               p += sprintf(p, "B%d", bridge);
+       if (swim || !msd)
+               sprintf(p, "S%d", swim);
+
+       LOG_INFO("STLINK %s (API v%d) VID:PID %04X:%04X",
+               v_str,
+               h->version.jtag_api,
                h->vid,
                h->pid);
 
@@ -526,15 +1325,15 @@ static int stlink_usb_check_voltage(void *handle, float *target_voltage)
        struct stlink_usb_handle_s *h = handle;
        uint32_t adc_results[2];
 
-       /* only supported by stlink/v2 and for firmware >= 13 */
-       if (h->version.stlink == 1 || h->version.jtag < 13)
+       /* no error message, simply quit with error */
+       if (!(h->version.flags & STLINK_F_HAS_TARGET_VOLT))
                return ERROR_COMMAND_NOTFOUND;
 
        stlink_usb_init_buffer(handle, h->rx_ep, 8);
 
        h->cmdbuf[h->cmdidx++] = STLINK_GET_TARGET_VOLTAGE;
 
-       int result = stlink_usb_xfer(handle, h->databuf, 8);
+       int result = stlink_usb_xfer_noerrcheck(handle, h->databuf, 8);
 
        if (result != ERROR_OK)
                return result;
@@ -557,10 +1356,9 @@ static int stlink_usb_set_swdclk(void *handle, uint16_t clk_divisor)
 {
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       /* only supported by stlink/v2 and for firmware >= 22 */
-       if (h->version.stlink == 1 || h->version.jtag < 22)
+       if (!(h->version.flags & STLINK_F_HAS_SWD_SET_FREQ))
                return ERROR_COMMAND_NOTFOUND;
 
        stlink_usb_init_buffer(handle, h->rx_ep, 2);
@@ -578,19 +1376,43 @@ static int stlink_usb_set_swdclk(void *handle, uint16_t clk_divisor)
        return ERROR_OK;
 }
 
+static int stlink_usb_set_jtagclk(void *handle, uint16_t clk_divisor)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       assert(handle);
+
+       if (!(h->version.flags & STLINK_F_HAS_JTAG_SET_FREQ))
+               return ERROR_COMMAND_NOTFOUND;
+
+       stlink_usb_init_buffer(handle, h->rx_ep, 2);
+
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_JTAG_SET_FREQ;
+       h_u16_to_le(h->cmdbuf+h->cmdidx, clk_divisor);
+       h->cmdidx += 2;
+
+       int result = stlink_cmd_allow_retry(handle, h->databuf, 2);
+
+       if (result != ERROR_OK)
+               return result;
+
+       return ERROR_OK;
+}
+
 /** */
 static int stlink_usb_current_mode(void *handle, uint8_t *mode)
 {
        int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
        stlink_usb_init_buffer(handle, h->rx_ep, 2);
 
        h->cmdbuf[h->cmdidx++] = STLINK_GET_CURRENT_MODE;
 
-       res = stlink_usb_xfer(handle, h->databuf, 2);
+       res = stlink_usb_xfer_noerrcheck(handle, h->databuf, 2);
 
        if (res != ERROR_OK)
                return res;
@@ -606,13 +1428,13 @@ static int stlink_usb_mode_enter(void *handle, enum stlink_mode type)
        int rx_size = 0;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
        /* on api V2 we are able the read the latest command
         * status
         * TODO: we need the test on api V1 too
         */
-       if (h->jtag_api == STLINK_JTAG_API_V2)
+       if (h->version.jtag_api != STLINK_JTAG_API_V1)
                rx_size = 2;
 
        stlink_usb_init_buffer(handle, h->rx_ep, rx_size);
@@ -620,24 +1442,25 @@ static int stlink_usb_mode_enter(void *handle, enum stlink_mode type)
        switch (type) {
                case STLINK_MODE_DEBUG_JTAG:
                        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-                       if (h->jtag_api == STLINK_JTAG_API_V1)
+                       if (h->version.jtag_api == STLINK_JTAG_API_V1)
                                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV1_ENTER;
                        else
                                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_ENTER;
-                       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_ENTER_JTAG;
+                       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_ENTER_JTAG_NO_RESET;
                        break;
                case STLINK_MODE_DEBUG_SWD:
                        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-                       if (h->jtag_api == STLINK_JTAG_API_V1)
+                       if (h->version.jtag_api == STLINK_JTAG_API_V1)
                                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV1_ENTER;
                        else
                                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_ENTER;
-                       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_ENTER_SWD;
+                       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_ENTER_SWD_NO_RESET;
                        break;
                case STLINK_MODE_DEBUG_SWIM:
                        h->cmdbuf[h->cmdidx++] = STLINK_SWIM_COMMAND;
                        h->cmdbuf[h->cmdidx++] = STLINK_SWIM_ENTER;
-                       break;
+                       /* swim enter does not return any response or status */
+                       return stlink_usb_xfer_noerrcheck(handle, h->databuf, 0);
                case STLINK_MODE_DFU:
                case STLINK_MODE_MASS:
                default:
@@ -653,9 +1476,10 @@ static int stlink_usb_mode_leave(void *handle, enum stlink_mode type)
        int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       stlink_usb_init_buffer(handle, STLINK_NULL_EP, 0);
+       /* command with no reply, use a valid endpoint but zero size */
+       stlink_usb_init_buffer(handle, h->rx_ep, 0);
 
        switch (type) {
                case STLINK_MODE_DEBUG_JTAG:
@@ -676,7 +1500,7 @@ static int stlink_usb_mode_leave(void *handle, enum stlink_mode type)
                        return ERROR_FAIL;
        }
 
-       res = stlink_usb_xfer(handle, 0, 0);
+       res = stlink_usb_xfer_noerrcheck(handle, h->databuf, 0);
 
        if (res != ERROR_OK)
                return res;
@@ -693,22 +1517,19 @@ static enum stlink_mode stlink_get_mode(enum hl_transports t)
                return STLINK_MODE_DEBUG_SWD;
        case HL_TRANSPORT_JTAG:
                return STLINK_MODE_DEBUG_JTAG;
-       case HL_TRANSPORT_SWIM:
-               return STLINK_MODE_DEBUG_SWIM;
        default:
                return STLINK_MODE_UNKNOWN;
        }
 }
 
 /** */
-static int stlink_usb_init_mode(void *handle, bool connect_under_reset)
+static int stlink_usb_exit_mode(void *handle)
 {
        int res;
        uint8_t mode;
        enum stlink_mode emode;
-       struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
        res = stlink_usb_current_mode(handle, &mode);
 
@@ -735,12 +1556,25 @@ static int stlink_usb_init_mode(void *handle, bool connect_under_reset)
                        break;
        }
 
-       if (emode != STLINK_MODE_UNKNOWN) {
-               res = stlink_usb_mode_leave(handle, emode);
+       if (emode != STLINK_MODE_UNKNOWN)
+               return stlink_usb_mode_leave(handle, emode);
 
-               if (res != ERROR_OK)
-                       return res;
-       }
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_usb_init_mode(void *handle, bool connect_under_reset, int initial_interface_speed)
+{
+       int res;
+       uint8_t mode;
+       enum stlink_mode emode;
+       struct stlink_usb_handle_s *h = handle;
+
+       assert(handle);
+
+       res = stlink_usb_exit_mode(handle);
+       if (res != ERROR_OK)
+               return res;
 
        res = stlink_usb_current_mode(handle, &mode);
 
@@ -773,30 +1607,258 @@ static int stlink_usb_init_mode(void *handle, bool connect_under_reset)
        LOG_DEBUG("MODE: 0x%02X", mode);
 
        /* set selected mode */
-       emode = stlink_get_mode(h->transport);
+       emode = h->st_mode;
 
        if (emode == STLINK_MODE_UNKNOWN) {
                LOG_ERROR("selected mode (transport) not supported");
                return ERROR_FAIL;
        }
 
+       /* set the speed before entering the mode, as the chip discovery phase should be done at this speed too */
+       if (emode == STLINK_MODE_DEBUG_JTAG) {
+               if (h->version.flags & STLINK_F_HAS_JTAG_SET_FREQ) {
+                       stlink_dump_speed_map(stlink_khz_to_speed_map_jtag, ARRAY_SIZE(stlink_khz_to_speed_map_jtag));
+                       stlink_speed(h, initial_interface_speed, false);
+               }
+       } else if (emode == STLINK_MODE_DEBUG_SWD) {
+               if (h->version.flags & STLINK_F_HAS_SWD_SET_FREQ) {
+                       stlink_dump_speed_map(stlink_khz_to_speed_map_swd, ARRAY_SIZE(stlink_khz_to_speed_map_swd));
+                       stlink_speed(h, initial_interface_speed, false);
+               }
+       }
+
+       if (h->version.jtag_api == STLINK_JTAG_API_V3 &&
+                       (emode == STLINK_MODE_DEBUG_JTAG || emode == STLINK_MODE_DEBUG_SWD)) {
+               struct speed_map map[STLINK_V3_MAX_FREQ_NB];
+
+               stlink_get_com_freq(h, (emode == STLINK_MODE_DEBUG_JTAG), map);
+               stlink_dump_speed_map(map, ARRAY_SIZE(map));
+               stlink_speed(h, initial_interface_speed, false);
+       }
+
+       /* preliminary SRST assert:
+        * We want SRST is asserted before activating debug signals (mode_enter).
+        * As the required mode has not been set, the adapter may not know what pin to use.
+        * Tested firmware STLINK v2 JTAG v29 API v2 SWIM v0 uses T_NRST pin by default
+        * Tested firmware STLINK v2 JTAG v27 API v2 SWIM v6 uses T_NRST pin by default
+        * after power on, SWIM_RST stays unchanged */
+       if (connect_under_reset && emode != STLINK_MODE_DEBUG_SWIM)
+               stlink_usb_assert_srst(handle, 0);
+               /* do not check the return status here, we will
+                  proceed and enter the desired mode below
+                  and try asserting srst again. */
+
+       res = stlink_usb_mode_enter(handle, emode);
+       if (res != ERROR_OK)
+               return res;
+
+       /* assert SRST again: a little bit late but now the adapter knows for sure what pin to use */
        if (connect_under_reset) {
                res = stlink_usb_assert_srst(handle, 0);
                if (res != ERROR_OK)
                        return res;
        }
 
-       res = stlink_usb_mode_enter(handle, emode);
+       res = stlink_usb_current_mode(handle, &mode);
 
        if (res != ERROR_OK)
                return res;
 
-       res = stlink_usb_current_mode(handle, &mode);
+       LOG_DEBUG("MODE: 0x%02X", mode);
+
+       return ERROR_OK;
+}
+
+/* request status from last swim request */
+static int stlink_swim_status(void *handle)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int res;
+
+       stlink_usb_init_buffer(handle, h->rx_ep, 4);
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_READSTATUS;
+       /* error is checked by the caller */
+       res = stlink_usb_xfer_noerrcheck(handle, h->databuf, 4);
+       if (res != ERROR_OK)
+               return res;
+       return ERROR_OK;
+}
+/*
+       the purpose of this function is unknown...
+       capabilities? anyway for swim v6 it returns
+       0001020600000000
+*/
+__attribute__((unused))
+static int stlink_swim_cap(void *handle, uint8_t *cap)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int res;
 
+       stlink_usb_init_buffer(handle, h->rx_ep, 8);
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_READ_CAP;
+       h->cmdbuf[h->cmdidx++] = 0x01;
+       res = stlink_usb_xfer_noerrcheck(handle, h->databuf, 8);
        if (res != ERROR_OK)
                return res;
+       memcpy(cap, h->databuf, 8);
+       return ERROR_OK;
+}
 
-       LOG_DEBUG("MODE: 0x%02X", mode);
+/*     debug dongle assert/deassert sreset line */
+static int stlink_swim_assert_reset(void *handle, int reset)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int res;
+
+       stlink_usb_init_buffer(handle, h->rx_ep, 0);
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_COMMAND;
+       if (!reset)
+               h->cmdbuf[h->cmdidx++] = STLINK_SWIM_ASSERT_RESET;
+       else
+               h->cmdbuf[h->cmdidx++] = STLINK_SWIM_DEASSERT_RESET;
+       res = stlink_cmd_allow_retry(handle, h->databuf, 0);
+       if (res != ERROR_OK)
+               return res;
+       return ERROR_OK;
+}
+
+/*
+       send swim enter seq
+       1.3ms low then 750Hz then 1.5kHz
+*/
+static int stlink_swim_enter(void *handle)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int res;
+
+       stlink_usb_init_buffer(handle, h->rx_ep, 0);
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_ENTER_SEQ;
+       res = stlink_cmd_allow_retry(handle, h->databuf, 0);
+       if (res != ERROR_OK)
+               return res;
+       return ERROR_OK;
+}
+
+/*     switch high/low speed swim */
+static int stlink_swim_speed(void *handle, int speed)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int res;
+
+       stlink_usb_init_buffer(handle, h->rx_ep, 0);
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_SPEED;
+       if (speed)
+               h->cmdbuf[h->cmdidx++] = 1;
+       else
+               h->cmdbuf[h->cmdidx++] = 0;
+       res = stlink_cmd_allow_retry(handle, h->databuf, 0);
+       if (res != ERROR_OK)
+               return res;
+       return ERROR_OK;
+}
+
+/*
+       initiate srst from swim.
+       nrst is pulled low for 50us.
+*/
+static int stlink_swim_generate_rst(void *handle)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int res;
+
+       stlink_usb_init_buffer(handle, h->rx_ep, 0);
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_GEN_RST;
+       res = stlink_cmd_allow_retry(handle, h->databuf, 0);
+       if (res != ERROR_OK)
+               return res;
+       return ERROR_OK;
+}
+
+/*
+       send resynchronize sequence
+       swim is pulled low for 16us
+       reply is 64 clks low
+*/
+static int stlink_swim_resync(void *handle)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int res;
+
+       stlink_usb_init_buffer(handle, h->rx_ep, 0);
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_RESET;
+       res = stlink_cmd_allow_retry(handle, h->databuf, 0);
+       if (res != ERROR_OK)
+               return res;
+       return ERROR_OK;
+}
+
+static int stlink_swim_writebytes(void *handle, uint32_t addr, uint32_t len, const uint8_t *data)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int res;
+       unsigned int i;
+       unsigned int datalen = 0;
+       int cmdsize = STLINK_CMD_SIZE_V2;
+
+       if (len > STLINK_DATA_SIZE)
+               return ERROR_FAIL;
+
+       if (h->version.stlink == 1)
+               cmdsize = STLINK_SG_SIZE;
+
+       stlink_usb_init_buffer(handle, h->tx_ep, 0);
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_WRITEMEM;
+       h_u16_to_be(h->cmdbuf+h->cmdidx, len);
+       h->cmdidx += 2;
+       h_u32_to_be(h->cmdbuf+h->cmdidx, addr);
+       h->cmdidx += 4;
+       for (i = 0; i < len; i++) {
+               if (h->cmdidx == cmdsize)
+                       h->databuf[datalen++] = *(data++);
+               else
+                       h->cmdbuf[h->cmdidx++] = *(data++);
+       }
+       if (h->version.stlink == 1)
+               stlink_usb_set_cbw_transfer_datalength(handle, datalen);
+
+       res = stlink_cmd_allow_retry(handle, h->databuf, datalen);
+       if (res != ERROR_OK)
+               return res;
+       return ERROR_OK;
+}
+
+static int stlink_swim_readbytes(void *handle, uint32_t addr, uint32_t len, uint8_t *data)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int res;
+
+       if (len > STLINK_DATA_SIZE)
+               return ERROR_FAIL;
+
+       stlink_usb_init_buffer(handle, h->rx_ep, 0);
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_READMEM;
+       h_u16_to_be(h->cmdbuf+h->cmdidx, len);
+       h->cmdidx += 2;
+       h_u32_to_be(h->cmdbuf+h->cmdidx, addr);
+       h->cmdidx += 4;
+       res = stlink_cmd_allow_retry(handle, h->databuf, 0);
+       if (res != ERROR_OK)
+               return res;
+
+       stlink_usb_init_buffer(handle, h->rx_ep, len);
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_SWIM_READBUF;
+       res = stlink_usb_xfer_noerrcheck(handle, data, len);
+       if (res != ERROR_OK)
+               return res;
 
        return ERROR_OK;
 }
@@ -804,22 +1866,36 @@ static int stlink_usb_init_mode(void *handle, bool connect_under_reset)
 /** */
 static int stlink_usb_idcode(void *handle, uint32_t *idcode)
 {
-       int res;
+       int res, offset;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       stlink_usb_init_buffer(handle, h->rx_ep, 4);
+       /* there is no swim read core id cmd */
+       if (h->st_mode == STLINK_MODE_DEBUG_SWIM) {
+               *idcode = 0;
+               return ERROR_OK;
+       }
+
+       stlink_usb_init_buffer(handle, h->rx_ep, 12);
 
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_READCOREID;
+       if (h->version.jtag_api == STLINK_JTAG_API_V1) {
+               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_READCOREID;
+
+               res = stlink_usb_xfer_noerrcheck(handle, h->databuf, 4);
+               offset = 0;
+       } else {
+               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_READ_IDCODES;
 
-       res = stlink_usb_xfer(handle, h->databuf, 4);
+               res = stlink_usb_xfer_errcheck(handle, h->databuf, 12);
+               offset = 4;
+       }
 
        if (res != ERROR_OK)
                return res;
 
-       *idcode = le_to_h_u32(h->databuf);
+       *idcode = le_to_h_u32(h->databuf + offset);
 
        LOG_DEBUG("IDCODE: 0x%08" PRIX32, *idcode);
 
@@ -831,7 +1907,7 @@ static int stlink_usb_v2_read_debug_reg(void *handle, uint32_t addr, uint32_t *v
        struct stlink_usb_handle_s *h = handle;
        int res;
 
-       assert(handle != NULL);
+       assert(handle);
 
        stlink_usb_init_buffer(handle, h->rx_ep, 8);
 
@@ -852,12 +1928,12 @@ static int stlink_usb_write_debug_reg(void *handle, uint32_t addr, uint32_t val)
 {
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
        stlink_usb_init_buffer(handle, h->rx_ep, 2);
 
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-       if (h->jtag_api == STLINK_JTAG_API_V1)
+       if (h->version.jtag_api == STLINK_JTAG_API_V1)
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV1_WRITEDEBUGREG;
        else
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_WRITEDEBUGREG;
@@ -870,13 +1946,13 @@ static int stlink_usb_write_debug_reg(void *handle, uint32_t addr, uint32_t val)
 }
 
 /** */
-static void stlink_usb_trace_read(void *handle)
+static int stlink_usb_trace_read(void *handle, uint8_t *buf, size_t *size)
 {
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       if (h->trace.enabled && h->version.jtag >= STLINK_TRACE_MIN_VERSION) {
+       if (h->trace.enabled && (h->version.flags & STLINK_F_HAS_TRACE)) {
                int res;
 
                stlink_usb_init_buffer(handle, h->rx_ep, 10);
@@ -884,30 +1960,21 @@ static void stlink_usb_trace_read(void *handle)
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_GET_TRACE_NB;
 
-               res = stlink_usb_xfer(handle, h->databuf, 2);
-               if (res == ERROR_OK) {
-                       uint8_t buf[STLINK_TRACE_SIZE];
-                       size_t size = le_to_h_u16(h->databuf);
-
-                       if (size > 0) {
-                               size = size < sizeof(buf) ? size : sizeof(buf) - 1;
-
-                               res = stlink_usb_read_trace(handle, buf, size);
-                               if (res == ERROR_OK) {
-                                       if (h->trace.output_f) {
-                                               /* Log retrieved trace output */
-                                               if (fwrite(buf, 1, size, h->trace.output_f) > 0)
-                                                       fflush(h->trace.output_f);
-                                       }
-                               }
-                       }
+               res = stlink_usb_xfer_noerrcheck(handle, h->databuf, 2);
+               if (res != ERROR_OK)
+                       return res;
+
+               size_t bytes_avail = le_to_h_u16(h->databuf);
+               *size = bytes_avail < *size ? bytes_avail : *size;
+
+               if (*size > 0) {
+                       res = stlink_usb_read_trace(handle, buf, *size);
+                       if (res != ERROR_OK)
+                               return res;
+                       return ERROR_OK;
                }
        }
-}
-
-static int stlink_usb_trace_read_callback(void *handle)
-{
-       stlink_usb_trace_read(handle);
+       *size = 0;
        return ERROR_OK;
 }
 
@@ -925,8 +1992,6 @@ static enum target_state stlink_usb_v2_get_status(void *handle)
        else if (status & S_RESET_ST)
                return TARGET_RESET;
 
-       stlink_usb_trace_read(handle);
-
        return TARGET_RUNNING;
 }
 
@@ -936,19 +2001,18 @@ static enum target_state stlink_usb_state(void *handle)
        int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
        if (h->reconnect_pending) {
                LOG_INFO("Previous state query failed, trying to reconnect");
-               res = stlink_usb_mode_enter(handle, stlink_get_mode(h->transport));
-
+               res = stlink_usb_mode_enter(handle, h->st_mode);
                if (res != ERROR_OK)
                        return TARGET_UNKNOWN;
 
                h->reconnect_pending = false;
        }
 
-       if (h->jtag_api == STLINK_JTAG_API_V2) {
+       if (h->version.jtag_api != STLINK_JTAG_API_V1) {
                res = stlink_usb_v2_get_status(handle);
                if (res == TARGET_UNKNOWN)
                        h->reconnect_pending = true;
@@ -960,7 +2024,7 @@ static enum target_state stlink_usb_state(void *handle)
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_GETSTATUS;
 
-       res = stlink_usb_xfer(handle, h->databuf, 2);
+       res = stlink_usb_xfer_noerrcheck(handle, h->databuf, 2);
 
        if (res != ERROR_OK)
                return TARGET_UNKNOWN;
@@ -975,171 +2039,108 @@ static enum target_state stlink_usb_state(void *handle)
        return TARGET_UNKNOWN;
 }
 
-/** */
-static int stlink_usb_reset(void *handle)
+static int stlink_usb_assert_srst(void *handle, int srst)
 {
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
+
+       if (h->st_mode == STLINK_MODE_DEBUG_SWIM)
+               return stlink_swim_assert_reset(handle, srst);
+
+       if (h->version.stlink == 1)
+               return ERROR_COMMAND_NOTFOUND;
 
        stlink_usb_init_buffer(handle, h->rx_ep, 2);
 
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-
-       if (h->jtag_api == STLINK_JTAG_API_V1)
-               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV1_RESETSYS;
-       else
-               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_RESETSYS;
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_DRIVE_NRST;
+       h->cmdbuf[h->cmdidx++] = srst;
 
        return stlink_cmd_allow_retry(handle, h->databuf, 2);
 }
 
-static int stlink_usb_assert_srst(void *handle, int srst)
+/** */
+static void stlink_usb_trace_disable(void *handle)
 {
+       int res = ERROR_OK;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       if (h->jtag_api == STLINK_JTAG_API_V1)
-               return ERROR_COMMAND_NOTFOUND;
+       assert(h->version.flags & STLINK_F_HAS_TRACE);
 
-       stlink_usb_init_buffer(handle, h->rx_ep, 2);
+       LOG_DEBUG("Tracing: disable");
 
+       stlink_usb_init_buffer(handle, h->rx_ep, 2);
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_DRIVE_NRST;
-       h->cmdbuf[h->cmdidx++] = srst;
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_STOP_TRACE_RX;
+       res = stlink_usb_xfer_errcheck(handle, h->databuf, 2);
 
-       return stlink_cmd_allow_retry(handle, h->databuf, 2);
+       if (res == ERROR_OK)
+               h->trace.enabled = false;
 }
 
+
 /** */
-static int stlink_configure_target_trace_port(void *handle)
+static int stlink_usb_trace_enable(void *handle)
 {
        int res;
-       uint32_t reg;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       /* configure the TPI */
+       if (h->version.flags & STLINK_F_HAS_TRACE) {
+               stlink_usb_init_buffer(handle, h->rx_ep, 10);
 
-       /* enable the trace subsystem */
-       res = stlink_usb_v2_read_debug_reg(handle, DCB_DEMCR, &reg);
-       if (res != ERROR_OK)
-               goto out;
-       res = stlink_usb_write_debug_reg(handle, DCB_DEMCR, TRCENA|reg);
-       if (res != ERROR_OK)
-               goto out;
-       /* set the TPI clock prescaler */
-       res = stlink_usb_write_debug_reg(handle, TPI_ACPR, h->trace.prescale);
-       if (res != ERROR_OK)
-               goto out;
-       /* select the pin protocol.  The STLinkv2 only supports asynchronous
-        * UART emulation (NRZ) mode, so that's what we pick. */
-       res = stlink_usb_write_debug_reg(handle, TPI_SPPR, 0x02);
-       if (res != ERROR_OK)
-               goto out;
-       /* disable continuous formatting */
-       res = stlink_usb_write_debug_reg(handle, TPI_FFCR, (1<<8));
-       if (res != ERROR_OK)
-               goto out;
+               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
+               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_START_TRACE_RX;
+               h_u16_to_le(h->cmdbuf+h->cmdidx, (uint16_t)STLINK_TRACE_SIZE);
+               h->cmdidx += 2;
+               h_u32_to_le(h->cmdbuf+h->cmdidx, h->trace.source_hz);
+               h->cmdidx += 4;
 
-       /* configure the ITM */
+               res = stlink_usb_xfer_errcheck(handle, h->databuf, 2);
 
-       /* unlock access to the ITM registers */
-       res = stlink_usb_write_debug_reg(handle, ITM_LAR, 0xC5ACCE55);
-       if (res != ERROR_OK)
-               goto out;
-       /* enable trace with ATB ID 1 */
-       res = stlink_usb_write_debug_reg(handle, ITM_TCR, (1<<16)|(1<<0)|(1<<2));
-       if (res != ERROR_OK)
-               goto out;
-       /* trace privilege */
-       res = stlink_usb_write_debug_reg(handle, ITM_TPR, 1);
-       if (res != ERROR_OK)
-               goto out;
-       /* trace port enable (port 0) */
-       res = stlink_usb_write_debug_reg(handle, ITM_TER, (1<<0));
-       if (res != ERROR_OK)
-               goto out;
+               if (res == ERROR_OK)  {
+                       h->trace.enabled = true;
+                       LOG_DEBUG("Tracing: recording at %" PRIu32 "Hz", h->trace.source_hz);
+               }
+       } else {
+               LOG_ERROR("Tracing is not supported by this version.");
+               res = ERROR_FAIL;
+       }
 
-       res = ERROR_OK;
-out:
        return res;
 }
 
 /** */
-static void stlink_usb_trace_disable(void *handle)
+static int stlink_usb_reset(void *handle)
 {
-       int res = ERROR_OK;
        struct stlink_usb_handle_s *h = handle;
+       int retval;
 
-       assert(handle != NULL);
-
-       assert(h->version.jtag >= STLINK_TRACE_MIN_VERSION);
-
-       LOG_DEBUG("Tracing: disable");
+       assert(handle);
 
        stlink_usb_init_buffer(handle, h->rx_ep, 2);
-       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_STOP_TRACE_RX;
-       res = stlink_usb_xfer(handle, h->databuf, 2);
-
-       if (res == ERROR_OK) {
-               h->trace.enabled = false;
-               target_unregister_timer_callback(stlink_usb_trace_read_callback, handle);
-       }
-}
 
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
 
-/** */
-static int stlink_usb_trace_enable(void *handle)
-{
-       int res;
-       struct stlink_usb_handle_s *h = handle;
-
-       assert(handle != NULL);
-
-       if (h->version.jtag >= STLINK_TRACE_MIN_VERSION) {
-               uint32_t trace_hz;
-
-               res = stlink_configure_target_trace_port(handle);
-               if (res != ERROR_OK)
-                       LOG_ERROR("Unable to configure tracing on target");
-
-               trace_hz = h->trace.prescale > 0 ?
-                       h->trace.source_hz / (h->trace.prescale + 1) :
-                       h->trace.source_hz;
-
-               stlink_usb_init_buffer(handle, h->rx_ep, 10);
-
-               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_START_TRACE_RX;
-               h_u16_to_le(h->cmdbuf+h->cmdidx, (uint16_t)STLINK_TRACE_SIZE);
-               h->cmdidx += 2;
-               h_u32_to_le(h->cmdbuf+h->cmdidx, trace_hz);
-               h->cmdidx += 4;
+       if (h->version.jtag_api == STLINK_JTAG_API_V1)
+               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV1_RESETSYS;
+       else
+               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_RESETSYS;
 
-               res = stlink_usb_xfer(handle, h->databuf, 2);
+       retval = stlink_cmd_allow_retry(handle, h->databuf, 2);
+       if (retval != ERROR_OK)
+               return retval;
 
-               if (res == ERROR_OK)  {
-                       h->trace.enabled = true;
-                       LOG_DEBUG("Tracing: recording at %" PRIu32 "Hz", trace_hz);
-                       /* We need the trace read function to be called at a
-                        * high-enough frequency to ensure reasonable
-                        * "timeliness" in processing ITM/DWT data.
-                        * TODO: An alternative could be using the asynchronous
-                        * features of the libusb-1.0 API to queue up one or more
-                        * reads in advance and requeue them once they are
-                        * completed. */
-                       target_register_timer_callback(stlink_usb_trace_read_callback, 1, 1, handle);
-               }
-       } else {
-               LOG_ERROR("Tracing is not supported by this version.");
-               res = ERROR_FAIL;
+       if (h->trace.enabled) {
+               stlink_usb_trace_disable(h);
+               return stlink_usb_trace_enable(h);
        }
 
-       return res;
+       return ERROR_OK;
 }
 
 /** */
@@ -1148,19 +2149,11 @@ static int stlink_usb_run(void *handle)
        int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       if (h->jtag_api == STLINK_JTAG_API_V2) {
+       if (h->version.jtag_api != STLINK_JTAG_API_V1) {
                res = stlink_usb_write_debug_reg(handle, DCB_DHCSR, DBGKEY|C_DEBUGEN);
 
-               /* Try to start tracing, if requested */
-               if (res == ERROR_OK && h->trace.source_hz && !h->trace.enabled) {
-                       if (stlink_usb_trace_enable(handle) == ERROR_OK)
-                               LOG_DEBUG("Tracing: enabled");
-                       else
-                               LOG_ERROR("Tracing: enable failed");
-               }
-
                return res;
        }
 
@@ -1178,14 +2171,11 @@ static int stlink_usb_halt(void *handle)
        int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       if (h->jtag_api == STLINK_JTAG_API_V2) {
+       if (h->version.jtag_api != STLINK_JTAG_API_V1) {
                res = stlink_usb_write_debug_reg(handle, DCB_DHCSR, DBGKEY|C_HALT|C_DEBUGEN);
 
-               if (res == ERROR_OK && h->trace.enabled)
-                       stlink_usb_trace_disable(handle);
-
                return res;
        }
 
@@ -1202,11 +2192,11 @@ static int stlink_usb_step(void *handle)
 {
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       if (h->jtag_api == STLINK_JTAG_API_V2) {
+       if (h->version.jtag_api != STLINK_JTAG_API_V1) {
                /* TODO: this emulates the v1 api, it should really use a similar auto mask isr
-                * that the cortex-m3 currently does. */
+                * that the Cortex-M3 currently does. */
                stlink_usb_write_debug_reg(handle, DCB_DHCSR, DBGKEY|C_HALT|C_MASKINTS|C_DEBUGEN);
                stlink_usb_write_debug_reg(handle, DCB_DHCSR, DBGKEY|C_STEP|C_MASKINTS|C_DEBUGEN);
                return stlink_usb_write_debug_reg(handle, DCB_DHCSR, DBGKEY|C_HALT|C_DEBUGEN);
@@ -1226,43 +2216,53 @@ static int stlink_usb_read_regs(void *handle)
        int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       stlink_usb_init_buffer(handle, h->rx_ep, 84);
+       stlink_usb_init_buffer(handle, h->rx_ep, 88);
 
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-       if (h->jtag_api == STLINK_JTAG_API_V1)
+       if (h->version.jtag_api == STLINK_JTAG_API_V1) {
+
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV1_READALLREGS;
-       else
+               res = stlink_usb_xfer_noerrcheck(handle, h->databuf, 84);
+               /* regs data from offset 0 */
+       } else {
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_READALLREGS;
+               res = stlink_usb_xfer_errcheck(handle, h->databuf, 88);
+               /* status at offset 0, regs data from offset 4 */
+       }
 
-       res = stlink_usb_xfer(handle, h->databuf, 84);
-
-       if (res != ERROR_OK)
-               return res;
-
-       return ERROR_OK;
+       return res;
 }
 
 /** */
-static int stlink_usb_read_reg(void *handle, int num, uint32_t *val)
+static int stlink_usb_read_reg(void *handle, unsigned int regsel, uint32_t *val)
 {
        int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
+
+       if (STLINK_REGSEL_IS_FPU(regsel) && !(h->version.flags & STLINK_F_HAS_FPU_REG)) {
+               res = stlink_usb_write_debug_reg(h, DCB_DCRSR, regsel & 0x7f);
+               if (res != ERROR_OK)
+                       return res;
+
+               /* FIXME: poll DHCSR.S_REGRDY before read DCRDR */
+               return stlink_usb_v2_read_debug_reg(h, DCB_DCRDR, val);
+       }
 
-       stlink_usb_init_buffer(handle, h->rx_ep, h->jtag_api == STLINK_JTAG_API_V1 ? 4 : 8);
+       stlink_usb_init_buffer(handle, h->rx_ep, h->version.jtag_api == STLINK_JTAG_API_V1 ? 4 : 8);
 
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-       if (h->jtag_api == STLINK_JTAG_API_V1)
+       if (h->version.jtag_api == STLINK_JTAG_API_V1)
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV1_READREG;
        else
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_READREG;
-       h->cmdbuf[h->cmdidx++] = num;
+       h->cmdbuf[h->cmdidx++] = regsel;
 
-       if (h->jtag_api == STLINK_JTAG_API_V1) {
-               res = stlink_usb_xfer(handle, h->databuf, 4);
+       if (h->version.jtag_api == STLINK_JTAG_API_V1) {
+               res = stlink_usb_xfer_noerrcheck(handle, h->databuf, 4);
                if (res != ERROR_OK)
                        return res;
                *val = le_to_h_u32(h->databuf);
@@ -1277,20 +2277,29 @@ static int stlink_usb_read_reg(void *handle, int num, uint32_t *val)
 }
 
 /** */
-static int stlink_usb_write_reg(void *handle, int num, uint32_t val)
+static int stlink_usb_write_reg(void *handle, unsigned int regsel, uint32_t val)
 {
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
+
+       if (STLINK_REGSEL_IS_FPU(regsel) && !(h->version.flags & STLINK_F_HAS_FPU_REG)) {
+               int res = stlink_usb_write_debug_reg(h, DCB_DCRDR, val);
+               if (res != ERROR_OK)
+                       return res;
+
+               return stlink_usb_write_debug_reg(h, DCB_DCRSR, DCRSR_WNR | (regsel & 0x7f));
+               /* FIXME: poll DHCSR.S_REGRDY after write DCRSR */
+       }
 
        stlink_usb_init_buffer(handle, h->rx_ep, 2);
 
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-       if (h->jtag_api == STLINK_JTAG_API_V1)
+       if (h->version.jtag_api == STLINK_JTAG_API_V1)
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV1_WRITEREG;
        else
                h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_WRITEREG;
-       h->cmdbuf[h->cmdidx++] = num;
+       h->cmdbuf[h->cmdidx++] = regsel;
        h_u32_to_le(h->cmdbuf+h->cmdidx, val);
        h->cmdidx += 4;
 
@@ -1299,25 +2308,23 @@ static int stlink_usb_write_reg(void *handle, int num, uint32_t val)
 
 static int stlink_usb_get_rw_status(void *handle)
 {
-       int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       if (h->jtag_api == STLINK_JTAG_API_V1)
+       if (h->version.jtag_api == STLINK_JTAG_API_V1)
                return ERROR_OK;
 
        stlink_usb_init_buffer(handle, h->rx_ep, 2);
 
        h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
-       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_GETLASTRWSTATUS;
-
-       res = stlink_usb_xfer(handle, h->databuf, 2);
-
-       if (res != ERROR_OK)
-               return res;
-
-       return stlink_usb_error_check(h);
+       if (h->version.flags & STLINK_F_HAS_GETLASTRWSTATUS2) {
+               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_GETLASTRWSTATUS2;
+               return stlink_usb_xfer_errcheck(handle, h->databuf, 12);
+       } else {
+               h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_GETLASTRWSTATUS;
+               return stlink_usb_xfer_errcheck(handle, h->databuf, 2);
+       }
 }
 
 /** */
@@ -1328,11 +2335,11 @@ static int stlink_usb_read_mem8(void *handle, uint32_t addr, uint16_t len,
        uint16_t read_len = len;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       /* max 8bit read/write is 64bytes */
-       if (len > STLINK_MAX_RW8) {
-               LOG_DEBUG("max buffer length exceeded");
+       /* max 8 bit read/write is 64 bytes or 512 bytes for v3 */
+       if (len > stlink_usb_block(h)) {
+               LOG_DEBUG("max buffer (%d) length exceeded", stlink_usb_block(h));
                return ERROR_FAIL;
        }
 
@@ -1349,7 +2356,7 @@ static int stlink_usb_read_mem8(void *handle, uint32_t addr, uint16_t len,
        if (read_len == 1)
                read_len++;
 
-       res = stlink_usb_xfer(handle, h->databuf, read_len);
+       res = stlink_usb_xfer_noerrcheck(handle, h->databuf, read_len);
 
        if (res != ERROR_OK)
                return res;
@@ -1366,11 +2373,11 @@ static int stlink_usb_write_mem8(void *handle, uint32_t addr, uint16_t len,
        int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
-       /* max 8bit read/write is 64bytes */
-       if (len > STLINK_MAX_RW8) {
-               LOG_DEBUG("max buffer length exceeded");
+       /* max 8 bit read/write is 64 bytes or 512 bytes for v3 */
+       if (len > stlink_usb_block(h)) {
+               LOG_DEBUG("max buffer length (%d) exceeded", stlink_usb_block(h));
                return ERROR_FAIL;
        }
 
@@ -1383,7 +2390,79 @@ static int stlink_usb_write_mem8(void *handle, uint32_t addr, uint16_t len,
        h_u16_to_le(h->cmdbuf+h->cmdidx, len);
        h->cmdidx += 2;
 
-       res = stlink_usb_xfer(handle, buffer, len);
+       res = stlink_usb_xfer_noerrcheck(handle, buffer, len);
+
+       if (res != ERROR_OK)
+               return res;
+
+       return stlink_usb_get_rw_status(handle);
+}
+
+/** */
+static int stlink_usb_read_mem16(void *handle, uint32_t addr, uint16_t len,
+                         uint8_t *buffer)
+{
+       int res;
+       struct stlink_usb_handle_s *h = handle;
+
+       assert(handle);
+
+       if (!(h->version.flags & STLINK_F_HAS_MEM_16BIT))
+               return ERROR_COMMAND_NOTFOUND;
+
+       /* data must be a multiple of 2 and half-word aligned */
+       if (len % 2 || addr % 2) {
+               LOG_DEBUG("Invalid data alignment");
+               return ERROR_TARGET_UNALIGNED_ACCESS;
+       }
+
+       stlink_usb_init_buffer(handle, h->rx_ep, len);
+
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_READMEM_16BIT;
+       h_u32_to_le(h->cmdbuf+h->cmdidx, addr);
+       h->cmdidx += 4;
+       h_u16_to_le(h->cmdbuf+h->cmdidx, len);
+       h->cmdidx += 2;
+
+       res = stlink_usb_xfer_noerrcheck(handle, h->databuf, len);
+
+       if (res != ERROR_OK)
+               return res;
+
+       memcpy(buffer, h->databuf, len);
+
+       return stlink_usb_get_rw_status(handle);
+}
+
+/** */
+static int stlink_usb_write_mem16(void *handle, uint32_t addr, uint16_t len,
+                          const uint8_t *buffer)
+{
+       int res;
+       struct stlink_usb_handle_s *h = handle;
+
+       assert(handle);
+
+       if (!(h->version.flags & STLINK_F_HAS_MEM_16BIT))
+               return ERROR_COMMAND_NOTFOUND;
+
+       /* data must be a multiple of 2 and half-word aligned */
+       if (len % 2 || addr % 2) {
+               LOG_DEBUG("Invalid data alignment");
+               return ERROR_TARGET_UNALIGNED_ACCESS;
+       }
+
+       stlink_usb_init_buffer(handle, h->tx_ep, len);
+
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_WRITEMEM_16BIT;
+       h_u32_to_le(h->cmdbuf+h->cmdidx, addr);
+       h->cmdidx += 4;
+       h_u16_to_le(h->cmdbuf+h->cmdidx, len);
+       h->cmdidx += 2;
+
+       res = stlink_usb_xfer_noerrcheck(handle, buffer, len);
 
        if (res != ERROR_OK)
                return res;
@@ -1398,7 +2477,7 @@ static int stlink_usb_read_mem32(void *handle, uint32_t addr, uint16_t len,
        int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
        /* data must be a multiple of 4 and word aligned */
        if (len % 4 || addr % 4) {
@@ -1415,7 +2494,7 @@ static int stlink_usb_read_mem32(void *handle, uint32_t addr, uint16_t len,
        h_u16_to_le(h->cmdbuf+h->cmdidx, len);
        h->cmdidx += 2;
 
-       res = stlink_usb_xfer(handle, h->databuf, len);
+       res = stlink_usb_xfer_noerrcheck(handle, h->databuf, len);
 
        if (res != ERROR_OK)
                return res;
@@ -1432,7 +2511,7 @@ static int stlink_usb_write_mem32(void *handle, uint32_t addr, uint16_t len,
        int res;
        struct stlink_usb_handle_s *h = handle;
 
-       assert(handle != NULL);
+       assert(handle);
 
        /* data must be a multiple of 4 and word aligned */
        if (len % 4 || addr % 4) {
@@ -1449,7 +2528,7 @@ static int stlink_usb_write_mem32(void *handle, uint32_t addr, uint16_t len,
        h_u16_to_le(h->cmdbuf+h->cmdidx, len);
        h->cmdidx += 2;
 
-       res = stlink_usb_xfer(handle, buffer, len);
+       res = stlink_usb_xfer_noerrcheck(handle, buffer, len);
 
        if (res != ERROR_OK)
                return res;
@@ -1476,30 +2555,38 @@ static int stlink_usb_read_mem(void *handle, uint32_t addr, uint32_t size,
        /* calculate byte count */
        count *= size;
 
+       /* switch to 8 bit if stlink does not support 16 bit memory read */
+       if (size == 2 && !(h->version.flags & STLINK_F_HAS_MEM_16BIT))
+               size = 1;
+
        while (count) {
 
-               bytes_remaining = (size == 4) ? \
-                               stlink_max_block_size(h->max_mem_packet, addr) : STLINK_MAX_RW8;
+               bytes_remaining = (size != 1) ?
+                               stlink_max_block_size(h->max_mem_packet, addr) : stlink_usb_block(h);
 
                if (count < bytes_remaining)
                        bytes_remaining = count;
 
-               /* the stlink only supports 8/32bit memory read/writes
-                * honour 32bit, all others will be handled as 8bit access */
-               if (size == 4) {
+               /*
+                * all stlink support 8/32bit memory read/writes and only from
+                * stlink V2J26 there is support for 16 bit memory read/write.
+                * Honour 32 bit and, if possible, 16 bit too. Otherwise, handle
+                * as 8bit access.
+                */
+               if (size != 1) {
 
-                       /* When in jtag mode the stlink uses the auto-increment functinality.
+                       /* When in jtag mode the stlink uses the auto-increment functionality.
                         * However it expects us to pass the data correctly, this includes
                         * alignment and any page boundaries. We already do this as part of the
                         * adi_v5 implementation, but the stlink is a hla adapter and so this
-                        * needs implementiong manually.
+                        * needs implementing manually.
                         * currently this only affects jtag mode, according to ST they do single
                         * access in SWD mode - but this may change and so we do it for both modes */
 
                        /* we first need to check for any unaligned bytes */
-                       if (addr % 4) {
+                       if (addr & (size - 1)) {
 
-                               uint32_t head_bytes = 4 - (addr % 4);
+                               uint32_t head_bytes = size - (addr & (size - 1));
                                retval = stlink_usb_read_mem8(handle, addr, head_bytes, buffer);
                                if (retval == ERROR_WAIT && retries < MAX_WAIT_RETRIES) {
                                        usleep((1<<retries++) * 1000);
@@ -1513,8 +2600,10 @@ static int stlink_usb_read_mem(void *handle, uint32_t addr, uint32_t size,
                                bytes_remaining -= head_bytes;
                        }
 
-                       if (bytes_remaining % 4)
+                       if (bytes_remaining & (size - 1))
                                retval = stlink_usb_read_mem(handle, addr, 1, bytes_remaining, buffer);
+                       else if (size == 2)
+                               retval = stlink_usb_read_mem16(handle, addr, bytes_remaining, buffer);
                        else
                                retval = stlink_usb_read_mem32(handle, addr, bytes_remaining, buffer);
                } else
@@ -1546,30 +2635,38 @@ static int stlink_usb_write_mem(void *handle, uint32_t addr, uint32_t size,
        /* calculate byte count */
        count *= size;
 
+       /* switch to 8 bit if stlink does not support 16 bit memory read */
+       if (size == 2 && !(h->version.flags & STLINK_F_HAS_MEM_16BIT))
+               size = 1;
+
        while (count) {
 
-               bytes_remaining = (size == 4) ? \
-                               stlink_max_block_size(h->max_mem_packet, addr) : STLINK_MAX_RW8;
+               bytes_remaining = (size != 1) ?
+                               stlink_max_block_size(h->max_mem_packet, addr) : stlink_usb_block(h);
 
                if (count < bytes_remaining)
                        bytes_remaining = count;
 
-               /* the stlink only supports 8/32bit memory read/writes
-                * honour 32bit, all others will be handled as 8bit access */
-               if (size == 4) {
+               /*
+                * all stlink support 8/32bit memory read/writes and only from
+                * stlink V2J26 there is support for 16 bit memory read/write.
+                * Honour 32 bit and, if possible, 16 bit too. Otherwise, handle
+                * as 8bit access.
+                */
+               if (size != 1) {
 
-                       /* When in jtag mode the stlink uses the auto-increment functinality.
+                       /* When in jtag mode the stlink uses the auto-increment functionality.
                         * However it expects us to pass the data correctly, this includes
                         * alignment and any page boundaries. We already do this as part of the
                         * adi_v5 implementation, but the stlink is a hla adapter and so this
-                        * needs implementiong manually.
+                        * needs implementing manually.
                         * currently this only affects jtag mode, according to ST they do single
                         * access in SWD mode - but this may change and so we do it for both modes */
 
                        /* we first need to check for any unaligned bytes */
-                       if (addr % 4) {
+                       if (addr & (size - 1)) {
 
-                               uint32_t head_bytes = 4 - (addr % 4);
+                               uint32_t head_bytes = size - (addr & (size - 1));
                                retval = stlink_usb_write_mem8(handle, addr, head_bytes, buffer);
                                if (retval == ERROR_WAIT && retries < MAX_WAIT_RETRIES) {
                                        usleep((1<<retries++) * 1000);
@@ -1583,8 +2680,10 @@ static int stlink_usb_write_mem(void *handle, uint32_t addr, uint32_t size,
                                bytes_remaining -= head_bytes;
                        }
 
-                       if (bytes_remaining % 4)
+                       if (bytes_remaining & (size - 1))
                                retval = stlink_usb_write_mem(handle, addr, 1, bytes_remaining, buffer);
+                       else if (size == 2)
+                               retval = stlink_usb_write_mem16(handle, addr, bytes_remaining, buffer);
                        else
                                retval = stlink_usb_write_mem32(handle, addr, bytes_remaining, buffer);
 
@@ -1611,166 +2710,470 @@ static int stlink_usb_override_target(const char *targetname)
        return !strcmp(targetname, "cortex_m");
 }
 
-static int stlink_speed(void *handle, int khz, bool query)
+static int stlink_speed_swim(void *handle, int khz, bool query)
+{
+       int retval;
+
+       /*
+                       we only have low and high speed...
+                       before changing speed the SWIM_CSR HS bit
+                       must be updated
+        */
+       if (!query) {
+               retval = stlink_swim_speed(handle, (khz < SWIM_FREQ_HIGH) ? 0 : 1);
+               if (retval != ERROR_OK)
+                       LOG_ERROR("Unable to set adapter speed");
+       }
+
+       return (khz < SWIM_FREQ_HIGH) ? SWIM_FREQ_LOW : SWIM_FREQ_HIGH;
+}
+
+static int stlink_match_speed_map(const struct speed_map *map, unsigned int map_size, int khz, bool query)
 {
-       unsigned i;
+       unsigned int i;
        int speed_index = -1;
        int speed_diff = INT_MAX;
-       struct stlink_usb_handle_s *h = handle;
-
-       /* only supported by stlink/v2 and for firmware >= 22 */
-       if (h && (h->version.stlink == 1 || h->version.jtag < 22))
-               return khz;
+       int last_valid_speed = -1;
+       bool match = true;
 
-       for (i = 0; i < ARRAY_SIZE(stlink_khz_to_speed_map); i++) {
-               if (khz == stlink_khz_to_speed_map[i].speed) {
+       for (i = 0; i < map_size; i++) {
+               if (!map[i].speed)
+                       continue;
+               last_valid_speed = i;
+               if (khz == map[i].speed) {
                        speed_index = i;
                        break;
                } else {
-                       int current_diff = khz - stlink_khz_to_speed_map[i].speed;
+                       int current_diff = khz - map[i].speed;
                        /* get abs value for comparison */
                        current_diff = (current_diff > 0) ? current_diff : -current_diff;
-                       if ((current_diff < speed_diff) && khz >= stlink_khz_to_speed_map[i].speed) {
+                       if ((current_diff < speed_diff) && khz >= map[i].speed) {
                                speed_diff = current_diff;
                                speed_index = i;
                        }
                }
        }
 
-       bool match = true;
-
        if (speed_index == -1) {
                /* this will only be here if we cannot match the slow speed.
                 * use the slowest speed we support.*/
-               speed_index = ARRAY_SIZE(stlink_khz_to_speed_map) - 1;
+               speed_index = last_valid_speed;
                match = false;
-       } else if (i == ARRAY_SIZE(stlink_khz_to_speed_map))
+       } else if (i == map_size)
                match = false;
 
        if (!match && query) {
-               LOG_INFO("Unable to match requested speed %d kHz, using %d kHz", \
-                               khz, stlink_khz_to_speed_map[speed_index].speed);
+               LOG_INFO("Unable to match requested speed %d kHz, using %d kHz",
+                               khz, map[speed_index].speed);
        }
 
-       if (h && !query) {
-               int result = stlink_usb_set_swdclk(h, stlink_khz_to_speed_map[speed_index].speed_divisor);
+       return speed_index;
+}
+
+static int stlink_speed_swd(void *handle, int khz, bool query)
+{
+       int speed_index;
+       struct stlink_usb_handle_s *h = handle;
+
+       /* old firmware cannot change it */
+       if (!(h->version.flags & STLINK_F_HAS_SWD_SET_FREQ))
+               return khz;
+
+       speed_index = stlink_match_speed_map(stlink_khz_to_speed_map_swd,
+               ARRAY_SIZE(stlink_khz_to_speed_map_swd), khz, query);
+
+       if (!query) {
+               int result = stlink_usb_set_swdclk(h, stlink_khz_to_speed_map_swd[speed_index].speed_divisor);
                if (result != ERROR_OK) {
                        LOG_ERROR("Unable to set adapter speed");
                        return khz;
                }
        }
 
-       return stlink_khz_to_speed_map[speed_index].speed;
+       return stlink_khz_to_speed_map_swd[speed_index].speed;
 }
 
-/** */
-static int stlink_usb_close(void *handle)
+static int stlink_speed_jtag(void *handle, int khz, bool query)
 {
+       int speed_index;
        struct stlink_usb_handle_s *h = handle;
 
-       if (h && h->fd)
-               jtag_libusb_close(h->fd);
+       /* old firmware cannot change it */
+       if (!(h->version.flags & STLINK_F_HAS_JTAG_SET_FREQ))
+               return khz;
 
-       free(h);
+       speed_index = stlink_match_speed_map(stlink_khz_to_speed_map_jtag,
+               ARRAY_SIZE(stlink_khz_to_speed_map_jtag), khz, query);
 
-       return ERROR_OK;
+       if (!query) {
+               int result = stlink_usb_set_jtagclk(h, stlink_khz_to_speed_map_jtag[speed_index].speed_divisor);
+               if (result != ERROR_OK) {
+                       LOG_ERROR("Unable to set adapter speed");
+                       return khz;
+               }
+       }
+
+       return stlink_khz_to_speed_map_jtag[speed_index].speed;
 }
 
-/** */
-static int stlink_usb_open(struct hl_interface_param_s *param, void **fd)
+static void stlink_dump_speed_map(const struct speed_map *map, unsigned int map_size)
 {
-       int err, retry_count = 1;
-       struct stlink_usb_handle_s *h;
-       enum stlink_jtag_api_version api;
+       unsigned int i;
 
-       LOG_DEBUG("stlink_usb_open");
+       LOG_DEBUG("Supported clock speeds are:");
+       for (i = 0; i < map_size; i++)
+               if (map[i].speed)
+                       LOG_DEBUG("%d kHz", map[i].speed);
+}
 
-       h = calloc(1, sizeof(struct stlink_usb_handle_s));
+static int stlink_get_com_freq(void *handle, bool is_jtag, struct speed_map *map)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int i;
 
-       if (h == 0) {
-               LOG_DEBUG("malloc failed");
-               return ERROR_FAIL;
+       if (h->version.jtag_api != STLINK_JTAG_API_V3) {
+               LOG_ERROR("Unknown command");
+               return 0;
        }
 
-       h->transport = param->transport;
+       stlink_usb_init_buffer(handle, h->rx_ep, 16);
 
-       const uint16_t vids[] = { param->vid, 0 };
-       const uint16_t pids[] = { param->pid, 0 };
-       const char *serial = param->serial;
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_APIV3_GET_COM_FREQ;
+       h->cmdbuf[h->cmdidx++] = is_jtag ? 1 : 0;
 
-       LOG_DEBUG("transport: %d vid: 0x%04x pid: 0x%04x serial: %s",
-                       param->transport, param->vid, param->pid,
-                       param->serial ? param->serial : "");
+       int res = stlink_usb_xfer_errcheck(handle, h->databuf, 52);
 
-       /*
-         On certain host USB configurations(e.g. MacBook Air)
-         STLINKv2 dongle seems to have its FW in a funky state if,
-         after plugging it in, you try to use openocd with it more
-         then once (by launching and closing openocd). In cases like
-         that initial attempt to read the FW info via
-         stlink_usb_version will fail and the device has to be reset
-         in order to become operational.
-        */
-       do {
-               if (jtag_libusb_open(vids, pids, serial, &h->fd) != ERROR_OK) {
-                       LOG_ERROR("open failed");
-                       goto error_open;
-               }
+       int size = h->databuf[8];
 
-               jtag_libusb_set_configuration(h->fd, 0);
+       if (size > STLINK_V3_MAX_FREQ_NB)
+               size = STLINK_V3_MAX_FREQ_NB;
 
-               if (jtag_libusb_claim_interface(h->fd, 0) != ERROR_OK) {
-                       LOG_DEBUG("claim interface failed");
-                       goto error_open;
-               }
+       for (i = 0; i < size; i++) {
+               map[i].speed = le_to_h_u32(&h->databuf[12 + 4 * i]);
+               map[i].speed_divisor = i;
+       }
 
-               /* RX EP is common for all versions */
-               h->rx_ep = STLINK_RX_EP;
+       /* set to zero all the next entries */
+       for (i = size; i < STLINK_V3_MAX_FREQ_NB; i++)
+               map[i].speed = 0;
 
-               /* wrap version for first read */
-               switch (param->pid) {
-                       case STLINK_V1_PID:
-                               h->version.stlink = 1;
-                               h->tx_ep = STLINK_TX_EP;
-                               h->trace_ep = STLINK_TRACE_EP;
-                               break;
-                       case STLINK_V2_1_PID:
-                               h->version.stlink = 2;
-                               h->tx_ep = STLINK_V2_1_TX_EP;
-                               h->trace_ep = STLINK_V2_1_TRACE_EP;
-                               break;
-                       default:
-                       /* fall through - we assume V2 to be the default version*/
-                       case STLINK_V2_PID:
-                               h->version.stlink = 2;
-                               h->tx_ep = STLINK_TX_EP;
-                               h->trace_ep = STLINK_TRACE_EP;
-                               break;
-               }
+       return res;
+}
 
-               /* get the device version */
-               err = stlink_usb_version(h);
+static int stlink_set_com_freq(void *handle, bool is_jtag, unsigned int frequency)
+{
+       struct stlink_usb_handle_s *h = handle;
 
-               if (err == ERROR_OK) {
-                       break;
-               } else if (h->version.stlink == 1 ||
-                          retry_count == 0) {
-                       LOG_ERROR("read version failed");
-                       goto error_open;
-               } else {
-                       err = jtag_libusb_release_interface(h->fd, 0);
-                       if (err != ERROR_OK) {
-                               LOG_ERROR("release interface failed");
-                               goto error_open;
-                       }
+       if (h->version.jtag_api != STLINK_JTAG_API_V3) {
+               LOG_ERROR("Unknown command");
+               return 0;
+       }
 
-                       err = jtag_libusb_reset_device(h->fd);
+       stlink_usb_init_buffer(handle, h->rx_ep, 16);
+
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_APIV3_SET_COM_FREQ;
+       h->cmdbuf[h->cmdidx++] = is_jtag ? 1 : 0;
+       h->cmdbuf[h->cmdidx++] = 0;
+
+       h_u32_to_le(&h->cmdbuf[4], frequency);
+
+       return stlink_usb_xfer_errcheck(handle, h->databuf, 8);
+}
+
+static int stlink_speed_v3(void *handle, bool is_jtag, int khz, bool query)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int speed_index;
+       struct speed_map map[STLINK_V3_MAX_FREQ_NB];
+
+       stlink_get_com_freq(h, is_jtag, map);
+
+       speed_index = stlink_match_speed_map(map, ARRAY_SIZE(map), khz, query);
+
+       if (!query) {
+               int result = stlink_set_com_freq(h, is_jtag, map[speed_index].speed);
+               if (result != ERROR_OK) {
+                       LOG_ERROR("Unable to set adapter speed");
+                       return khz;
+               }
+       }
+       return map[speed_index].speed;
+}
+
+static int stlink_speed(void *handle, int khz, bool query)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       if (!handle)
+               return khz;
+
+       switch (h->st_mode) {
+       case STLINK_MODE_DEBUG_SWIM:
+               return stlink_speed_swim(handle, khz, query);
+       case STLINK_MODE_DEBUG_SWD:
+               if (h->version.jtag_api == STLINK_JTAG_API_V3)
+                       return stlink_speed_v3(handle, false, khz, query);
+               else
+                       return stlink_speed_swd(handle, khz, query);
+               break;
+       case STLINK_MODE_DEBUG_JTAG:
+               if (h->version.jtag_api == STLINK_JTAG_API_V3)
+                       return stlink_speed_v3(handle, true, khz, query);
+               else
+                       return stlink_speed_jtag(handle, khz, query);
+               break;
+       default:
+               break;
+       }
+
+       return khz;
+}
+
+/** */
+static int stlink_usb_usb_close(void *handle)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       if (!h)
+               return ERROR_OK;
+
+       if (h->usb_backend_priv.fd) {
+               stlink_usb_exit_mode(h);
+               /* do not check return code, it prevent
+               us from closing jtag_libusb */
+               jtag_libusb_close(h->usb_backend_priv.fd);
+       }
+
+       free(h->cmdbuf);
+       free(h->databuf);
+
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_tcp_close(void *handle)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       if (!h)
+               return ERROR_OK;
+
+       int ret = ERROR_OK;
+       if (h->tcp_backend_priv.connected) {
+               if (h->tcp_backend_priv.connect_id) {
+                       stlink_usb_exit_mode(h);
+
+                       /* close the stlink */
+                       h->tcp_backend_priv.send_buf[0] = STLINK_TCP_CMD_CLOSE_DEV;
+                       memset(&h->tcp_backend_priv.send_buf[1], 0, 4); /* reserved */
+                       h_u32_to_le(&h->tcp_backend_priv.send_buf[4], h->tcp_backend_priv.connect_id);
+                       ret = stlink_tcp_send_cmd(h, 8, 4, true);
+                       if (ret != ERROR_OK)
+                               LOG_ERROR("cannot close the STLINK");
+               }
+
+               if (close_socket(h->tcp_backend_priv.fd) != 0)
+                       LOG_ERROR("error closing the socket, errno: %s", strerror(errno));
+       }
+
+       free(h->tcp_backend_priv.send_buf);
+       free(h->tcp_backend_priv.recv_buf);
+
+       return ret;
+}
+
+/** */
+static int stlink_close(void *handle)
+{
+       if (handle) {
+               struct stlink_usb_handle_s *h = handle;
+
+               stlink_usb_close(handle);
+
+               free(h);
+       }
+
+       return ERROR_OK;
+}
+
+/* Compute ST-Link serial number from the device descriptor
+ * this function will help to work-around a bug in old ST-Link/V2 DFU
+ * the buggy DFU returns an incorrect serial in the USB descriptor
+ * example for the following serial "57FF72067265575742132067"
+ *  - the correct descriptor serial is:
+ *    0x32, 0x03, 0x35, 0x00, 0x37, 0x00, 0x46, 0x00, 0x46, 0x00, 0x37, 0x00, 0x32, 0x00 ...
+ *    this contains the length (0x32 = 50), the type (0x3 = DT_STRING) and the serial in unicode format
+ *    the serial part is: 0x0035, 0x0037, 0x0046, 0x0046, 0x0037, 0x0032 ... >>  57FF72 ...
+ *    this format could be read correctly by 'libusb_get_string_descriptor_ascii'
+ *    so this case is managed by libusb_helper::string_descriptor_equal
+ *  - the buggy DFU is not doing any unicode conversion and returns a raw serial data in the descriptor
+ *    0x1a, 0x03, 0x57, 0x00, 0xFF, 0x00, 0x72, 0x00 ...
+ *            >>    57          FF          72       ...
+ *    based on the length (0x1a = 26) we could easily decide if we have to fixup the serial
+ *    and then we have just to convert the raw data into printable characters using sprintf
+ */
+static char *stlink_usb_get_alternate_serial(struct libusb_device_handle *device,
+               struct libusb_device_descriptor *dev_desc)
+{
+       int usb_retval;
+       unsigned char desc_serial[(STLINK_SERIAL_LEN + 1) * 2];
+
+       if (dev_desc->iSerialNumber == 0)
+               return NULL;
+
+       /* get the LANGID from String Descriptor Zero */
+       usb_retval = libusb_get_string_descriptor(device, 0, 0, desc_serial,
+                       sizeof(desc_serial));
+
+       if (usb_retval < LIBUSB_SUCCESS) {
+               LOG_ERROR("libusb_get_string_descriptor() failed: %s(%d)",
+                               libusb_error_name(usb_retval), usb_retval);
+               return NULL;
+       } else if (usb_retval < 4) {
+               /* the size should be least 4 bytes to contain a minimum of 1 supported LANGID */
+               LOG_ERROR("could not get the LANGID");
+               return NULL;
+       }
+
+       uint32_t langid = desc_serial[2] | (desc_serial[3] << 8);
+
+       /* get the serial */
+       usb_retval = libusb_get_string_descriptor(device, dev_desc->iSerialNumber,
+                       langid, desc_serial, sizeof(desc_serial));
+
+       unsigned char len = desc_serial[0];
+
+       if (usb_retval < LIBUSB_SUCCESS) {
+               LOG_ERROR("libusb_get_string_descriptor() failed: %s(%d)",
+                               libusb_error_name(usb_retval), usb_retval);
+               return NULL;
+       } else if (desc_serial[1] != LIBUSB_DT_STRING || len > usb_retval) {
+               LOG_ERROR("invalid string in ST-LINK USB serial descriptor");
+               return NULL;
+       }
+
+       if (len == ((STLINK_SERIAL_LEN + 1) * 2)) {
+               /* good ST-Link adapter, this case is managed by
+                * libusb::libusb_get_string_descriptor_ascii */
+               return NULL;
+       } else if (len != ((STLINK_SERIAL_LEN / 2 + 1) * 2)) {
+               LOG_ERROR("unexpected serial length (%d) in descriptor", len);
+               return NULL;
+       }
+
+       /* else (len == 26) => buggy ST-Link */
+
+       char *alternate_serial = malloc((STLINK_SERIAL_LEN + 1) * sizeof(char));
+       if (!alternate_serial)
+               return NULL;
+
+       for (unsigned int i = 0; i < STLINK_SERIAL_LEN; i += 2)
+               sprintf(alternate_serial + i, "%02X", desc_serial[i + 2]);
+
+       alternate_serial[STLINK_SERIAL_LEN] = '\0';
+
+       return alternate_serial;
+}
+
+/** */
+static int stlink_usb_usb_open(void *handle, struct hl_interface_param_s *param)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int err, retry_count = 1;
+
+       h->cmdbuf = malloc(STLINK_SG_SIZE);
+       h->databuf = malloc(STLINK_DATA_SIZE);
+
+       if (!h->cmdbuf || !h->databuf)
+               return ERROR_FAIL;
+
+       /*
+         On certain host USB configurations(e.g. MacBook Air)
+         STLINKv2 dongle seems to have its FW in a funky state if,
+         after plugging it in, you try to use openocd with it more
+         then once (by launching and closing openocd). In cases like
+         that initial attempt to read the FW info via
+         stlink_usb_version will fail and the device has to be reset
+         in order to become operational.
+        */
+       do {
+               if (jtag_libusb_open(param->vid, param->pid, param->serial,
+                               &h->usb_backend_priv.fd, stlink_usb_get_alternate_serial) != ERROR_OK) {
+                       LOG_ERROR("open failed");
+                       return ERROR_FAIL;
+               }
+
+               jtag_libusb_set_configuration(h->usb_backend_priv.fd, 0);
+
+               if (libusb_claim_interface(h->usb_backend_priv.fd, 0) != ERROR_OK) {
+                       LOG_DEBUG("claim interface failed");
+                       return ERROR_FAIL;
+               }
+
+               /* RX EP is common for all versions */
+               h->rx_ep = STLINK_RX_EP;
+
+               uint16_t pid;
+               if (jtag_libusb_get_pid(libusb_get_device(h->usb_backend_priv.fd), &pid) != ERROR_OK) {
+                       LOG_DEBUG("libusb_get_pid failed");
+                       return ERROR_FAIL;
+               }
+
+               /* wrap version for first read */
+               switch (pid) {
+                       case STLINK_V1_PID:
+                               h->version.stlink = 1;
+                               h->tx_ep = STLINK_TX_EP;
+                               break;
+                       case STLINK_V3_USBLOADER_PID:
+                       case STLINK_V3E_PID:
+                       case STLINK_V3S_PID:
+                       case STLINK_V3_2VCP_PID:
+                       case STLINK_V3E_NO_MSD_PID:
+                               h->version.stlink = 3;
+                               h->tx_ep = STLINK_V2_1_TX_EP;
+                               h->trace_ep = STLINK_V2_1_TRACE_EP;
+                               break;
+                       case STLINK_V2_1_PID:
+                       case STLINK_V2_1_NO_MSD_PID:
+                               h->version.stlink = 2;
+                               h->tx_ep = STLINK_V2_1_TX_EP;
+                               h->trace_ep = STLINK_V2_1_TRACE_EP;
+                               break;
+                       default:
+                       /* fall through - we assume V2 to be the default version*/
+                       case STLINK_V2_PID:
+                               h->version.stlink = 2;
+                               h->tx_ep = STLINK_TX_EP;
+                               h->trace_ep = STLINK_TRACE_EP;
+                               break;
+               }
+
+               /* get the device version */
+               err = stlink_usb_version(h);
+
+               if (err == ERROR_OK) {
+                       break;
+               } else if (h->version.stlink == 1 ||
+                          retry_count == 0) {
+                       LOG_ERROR("read version failed");
+                       return ERROR_FAIL;
+               } else {
+                       err = libusb_release_interface(h->usb_backend_priv.fd, 0);
+                       if (err != ERROR_OK) {
+                               LOG_ERROR("release interface failed");
+                               return ERROR_FAIL;
+                       }
+
+                       err = libusb_reset_device(h->usb_backend_priv.fd);
                        if (err != ERROR_OK) {
                                LOG_ERROR("reset device failed");
-                               goto error_open;
+                               return ERROR_FAIL;
                        }
 
-                       jtag_libusb_close(h->fd);
+                       jtag_libusb_close(h->usb_backend_priv.fd);
                        /*
                          Give the device one second to settle down and
                          reenumerate.
@@ -1780,132 +3183,1210 @@ static int stlink_usb_open(struct hl_interface_param_s *param, void **fd)
                }
        } while (1);
 
-       /* compare usb vid/pid */
-       if ((param->vid != h->vid) || (param->pid != h->pid))
-               LOG_INFO("vid/pid are not identical: 0x%04X/0x%04X 0x%04X/0x%04X",
-                       param->vid, param->pid,
-                       h->vid, h->pid);
+       return ERROR_OK;
+}
 
-       /* check if mode is supported */
-       err = ERROR_OK;
+/** */
+static int stlink_tcp_open(void *handle, struct hl_interface_param_s *param)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int ret;
 
-       switch (h->transport) {
-               case HL_TRANSPORT_SWD:
-               case HL_TRANSPORT_JTAG:
-                       if (h->version.jtag == 0)
-                               err = ERROR_FAIL;
-                       break;
-               case HL_TRANSPORT_SWIM:
-                       if (h->version.swim == 0)
-                               err = ERROR_FAIL;
-                       break;
-               default:
-                       err = ERROR_FAIL;
-                       break;
+       /* SWIM is not supported using stlink-server */
+       if (h->st_mode ==  STLINK_MODE_DEBUG_SWIM) {
+               LOG_ERROR("stlink-server does not support SWIM mode");
+               return ERROR_FAIL;
        }
 
-       if (err != ERROR_OK) {
-               LOG_ERROR("mode (transport) not supported by device");
-               goto error_open;
+       h->tcp_backend_priv.send_buf = malloc(STLINK_TCP_SEND_BUFFER_SIZE);
+       h->tcp_backend_priv.recv_buf = malloc(STLINK_TCP_RECV_BUFFER_SIZE);
+
+       if (!h->tcp_backend_priv.send_buf || !h->tcp_backend_priv.recv_buf)
+               return ERROR_FAIL;
+
+       h->cmdbuf = &h->tcp_backend_priv.send_buf[8];
+       h->databuf = &h->tcp_backend_priv.recv_buf[4];
+
+       /* configure directions */
+       h->rx_ep = STLINK_TCP_REQUEST_READ;
+       h->tx_ep = STLINK_TCP_REQUEST_WRITE;
+       h->trace_ep = STLINK_TCP_REQUEST_READ_SWO;
+
+       h->tcp_backend_priv.fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+       h->tcp_backend_priv.connected = false;
+       h->tcp_backend_priv.device_id = 0;
+       h->tcp_backend_priv.connect_id = 0;
+
+       if (h->tcp_backend_priv.fd == -1) {
+               LOG_ERROR("error creating the socket, errno: %s", strerror(errno));
+               return ERROR_FAIL;
        }
 
-       api = h->version.jtag_api_max;
+       struct sockaddr_in serv;
+       memset(&serv, 0, sizeof(struct sockaddr_in));
+       serv.sin_family = AF_INET;
+       serv.sin_port = htons(param->stlink_tcp_port);
+       serv.sin_addr.s_addr = inet_addr("127.0.0.1");
 
-       LOG_INFO("using stlink api v%d", api);
+       LOG_DEBUG("socket : %x", h->tcp_backend_priv.fd);
 
-       /* set the used jtag api, this will default to the newest supported version */
-       h->jtag_api = api;
+       int optval = 1;
+       if (setsockopt(h->tcp_backend_priv.fd, IPPROTO_TCP, TCP_NODELAY, (const void *)&optval, sizeof(int)) == -1) {
+               LOG_ERROR("cannot set sock option 'TCP_NODELAY', errno: %s", strerror(errno));
+               return ERROR_FAIL;
+       }
 
-       if (h->jtag_api >= 2 && param->trace_source_hz > 0) {
-               uint32_t prescale;
+       optval = STLINK_TCP_RECV_BUFFER_SIZE;
+       if (setsockopt(h->tcp_backend_priv.fd, SOL_SOCKET, SO_RCVBUF, (const void *)&optval, sizeof(int)) == -1) {
+               LOG_ERROR("cannot set sock option 'SO_RCVBUF', errno: %s", strerror(errno));
+               return ERROR_FAIL;
+       }
 
-               prescale = param->trace_source_hz > STLINK_TRACE_MAX_HZ ?
-                       (param->trace_source_hz / STLINK_TRACE_MAX_HZ) - 1 : 0;
+       optval = STLINK_TCP_SEND_BUFFER_SIZE;
+       if (setsockopt(h->tcp_backend_priv.fd, SOL_SOCKET, SO_SNDBUF, (const void *)&optval, sizeof(int)) == -1) {
+               LOG_ERROR("cannot set sock option 'SO_SNDBUF', errno: %s", strerror(errno));
+               return ERROR_FAIL;
+       }
 
-               h->trace.output_f = param->trace_f;
-               h->trace.source_hz = param->trace_source_hz;
-               h->trace.prescale = prescale;
+       if (connect(h->tcp_backend_priv.fd, (const struct sockaddr *)&serv, sizeof(serv)) == -1) {
+               LOG_ERROR("cannot connect to stlink server, errno: %s", strerror(errno));
+               return ERROR_FAIL;
        }
 
-       /* initialize the debug hardware */
-       err = stlink_usb_init_mode(h, param->connect_under_reset);
+       h->tcp_backend_priv.connected = true;
 
-       if (err != ERROR_OK) {
-               LOG_ERROR("init mode failed (unable to connect to the target)");
-               goto error_open;
+       LOG_INFO("connected to stlink-server");
+
+       /* print stlink-server version */
+       h->tcp_backend_priv.send_buf[0] = STLINK_TCP_CMD_GET_SERVER_VERSION;
+       h->tcp_backend_priv.send_buf[1] = OPENOCD_STLINK_TCP_API_VERSION;
+       memset(&h->tcp_backend_priv.send_buf[2], 0, 2); /* reserved */
+       ret = stlink_tcp_send_cmd(h, 4, 16, false);
+       if (ret != ERROR_OK) {
+               LOG_ERROR("cannot get the stlink-server version");
+               return ERROR_FAIL;
        }
 
-       /* clock speed only supported by stlink/v2 and for firmware >= 22 */
-       if (h->version.stlink >= 2 && h->version.jtag >= 22) {
-               LOG_DEBUG("Supported clock speeds are:");
+       uint32_t api_ver = le_to_h_u32(&h->tcp_backend_priv.recv_buf[0]);
+       uint32_t ver_major = le_to_h_u32(&h->tcp_backend_priv.recv_buf[4]);
+       uint32_t ver_minor = le_to_h_u32(&h->tcp_backend_priv.recv_buf[8]);
+       uint32_t ver_build = le_to_h_u32(&h->tcp_backend_priv.recv_buf[12]);
+       LOG_INFO("stlink-server API v%d, version %d.%d.%d",
+                       api_ver, ver_major, ver_minor, ver_build);
+
+       /* in stlink-server API v1 sending more than 1428 bytes will cause stlink-server
+        * to crash in windows: select a safe default value (1K) */
+       if (api_ver < 2)
+               h->max_mem_packet = (1 << 10);
+
+       /* refresh stlink list (re-enumerate) */
+       h->tcp_backend_priv.send_buf[0] = STLINK_TCP_CMD_REFRESH_DEVICE_LIST;
+       h->tcp_backend_priv.send_buf[1] = 0; /* don't clear the list, just refresh it */
+       ret = stlink_tcp_send_cmd(h, 2, 4, true);
+       if (ret != ERROR_OK)
+               return ret;
+
+       /* get the number of connected stlinks */
+       h->tcp_backend_priv.send_buf[0] = STLINK_TCP_CMD_GET_NB_DEV;
+       ret = stlink_tcp_send_cmd(h, 1, 4, false);
+       if (ret != ERROR_OK)
+               return ret;
+
+       uint32_t connected_stlinks = le_to_h_u32(h->tcp_backend_priv.recv_buf);
+
+       if (connected_stlinks == 0) {
+               LOG_ERROR("no ST-LINK detected");
+               return ERROR_FAIL;
+       }
 
-               for (unsigned i = 0; i < ARRAY_SIZE(stlink_khz_to_speed_map); i++)
-                       LOG_DEBUG("%d kHz", stlink_khz_to_speed_map[i].speed);
+       LOG_DEBUG("%d ST-LINK detected", connected_stlinks);
 
-               stlink_speed(h, param->initial_interface_speed, false);
+       if (connected_stlinks > 255) {
+               LOG_WARNING("STLink server cannot handle more than 255 ST-LINK connected");
+               connected_stlinks = 255;
        }
 
-       /* get cpuid, so we can determine the max page size
-        * start with a safe default */
-       h->max_mem_packet = (1 << 10);
+       /* list all connected ST-Link and seek for the requested vid:pid and serial */
+       char serial[STLINK_TCP_SERIAL_SIZE + 1] = {0};
+       uint8_t stlink_used;
+       bool stlink_id_matched = false;
+       bool stlink_serial_matched = (!param->serial);
+
+       for (uint32_t stlink_id = 0; stlink_id < connected_stlinks; stlink_id++) {
+               /* get the stlink info */
+               h->tcp_backend_priv.send_buf[0] = STLINK_TCP_CMD_GET_DEV_INFO;
+               h->tcp_backend_priv.send_buf[1] = (uint8_t)stlink_id;
+               memset(&h->tcp_backend_priv.send_buf[2], 0, 2); /* reserved */
+               h_u32_to_le(&h->tcp_backend_priv.send_buf[4], 41); /* size of TDeviceInfo2 */
+               ret = stlink_tcp_send_cmd(h, 8, 45, true);
+               if (ret != ERROR_OK)
+                       return ret;
+
+               h->tcp_backend_priv.device_id = le_to_h_u32(&h->tcp_backend_priv.recv_buf[4]);
+               memcpy(serial, &h->tcp_backend_priv.recv_buf[8], STLINK_TCP_SERIAL_SIZE);
+               h->vid = le_to_h_u16(&h->tcp_backend_priv.recv_buf[40]);
+               h->pid = le_to_h_u16(&h->tcp_backend_priv.recv_buf[42]);
+               stlink_used = h->tcp_backend_priv.recv_buf[44];
+
+               /* check the vid:pid */
+               for (int i = 0; param->vid[i]; i++) {
+                       if (param->vid[i] == h->vid && param->pid[i] == h->pid) {
+                               stlink_id_matched = true;
+                               break;
+                       }
+               }
+
+               if (!stlink_id_matched)
+                       continue;
+
+               /* check the serial if specified */
+               if (param->serial) {
+                       /* ST-Link server fixes the buggy serial returned by old ST-Link DFU
+                        * for further details refer to stlink_usb_get_alternate_serial
+                        * so if the user passes the buggy serial, we need to fix it before
+                        * comparing with the serial returned by ST-Link server */
+                       if (strlen(param->serial) == STLINK_SERIAL_LEN / 2) {
+                               char fixed_serial[STLINK_SERIAL_LEN + 1];
+
+                               for (unsigned int i = 0; i < STLINK_SERIAL_LEN; i += 2)
+                                       sprintf(fixed_serial + i, "%02X", param->serial[i / 2]);
+
+                               fixed_serial[STLINK_SERIAL_LEN] = '\0';
 
-       uint8_t buffer[4];
-       err = stlink_usb_read_mem32(h, CPUID, 4, buffer);
-       if (err == ERROR_OK) {
-               uint32_t cpuid = le_to_h_u32(buffer);
-               int i = (cpuid >> 4) & 0xf;
-               if (i == 4 || i == 3) {
-                       /* Cortex-M3/M4 has 4096 bytes autoincrement range */
-                       h->max_mem_packet = (1 << 12);
+                               stlink_serial_matched = strcmp(fixed_serial, serial) == 0;
+                       } else
+                               stlink_serial_matched = strcmp(param->serial, serial) == 0;
                }
+
+               if (!stlink_serial_matched)
+                       LOG_DEBUG("Device serial number '%s' doesn't match requested serial '%s'",
+                                       serial, param->serial);
+               else /* exit the search loop if there is match */
+                       break;
        }
 
-       LOG_DEBUG("Using TAR autoincrement: %" PRIu32, h->max_mem_packet);
+       if (!stlink_id_matched) {
+               LOG_ERROR("ST-LINK open failed (vid/pid mismatch)");
+               return ERROR_FAIL;
+       }
 
-       *fd = h;
+       if (!stlink_serial_matched) {
+               LOG_ERROR("ST-LINK open failed (serial mismatch)");
+               return ERROR_FAIL;
+       }
 
-       return ERROR_OK;
+       /* check if device is 'exclusively' used by another application */
+       if (stlink_used) {
+               LOG_ERROR("the selected device is already used");
+               return ERROR_FAIL;
+       }
 
-error_open:
-       stlink_usb_close(h);
+       LOG_DEBUG("transport: vid: 0x%04x pid: 0x%04x serial: %s", h->vid, h->pid, serial);
 
-       return ERROR_FAIL;
+       /* now let's open the stlink */
+       h->tcp_backend_priv.send_buf[0] = STLINK_TCP_CMD_OPEN_DEV;
+       memset(&h->tcp_backend_priv.send_buf[1], 0, 4); /* reserved */
+       h_u32_to_le(&h->tcp_backend_priv.send_buf[4], h->tcp_backend_priv.device_id);
+       ret = stlink_tcp_send_cmd(h, 8, 8, true);
+       if (ret != ERROR_OK)
+               return ret;
+
+       h->tcp_backend_priv.connect_id = le_to_h_u32(&h->tcp_backend_priv.recv_buf[4]);
+
+       /* get stlink version */
+       return stlink_usb_version(h);
 }
 
-/** */
-struct hl_layout_api_s stlink_usb_layout_api = {
-       /** */
-       .open = stlink_usb_open,
-       /** */
-       .close = stlink_usb_close,
-       /** */
-       .idcode = stlink_usb_idcode,
-       /** */
-       .state = stlink_usb_state,
-       /** */
-       .reset = stlink_usb_reset,
-       /** */
-       .assert_srst = stlink_usb_assert_srst,
-       /** */
-       .run = stlink_usb_run,
-       /** */
-       .halt = stlink_usb_halt,
-       /** */
-       .step = stlink_usb_step,
-       /** */
-       .read_regs = stlink_usb_read_regs,
-       /** */
-       .read_reg = stlink_usb_read_reg,
-       /** */
-       .write_reg = stlink_usb_write_reg,
-       /** */
-       .read_mem = stlink_usb_read_mem,
-       /** */
-       .write_mem = stlink_usb_write_mem,
-       /** */
-       .write_debug_reg = stlink_usb_write_debug_reg,
-       /** */
-       .override_target = stlink_usb_override_target,
-       /** */
-       .speed = stlink_speed,
+static struct stlink_backend_s stlink_usb_backend = {
+       .open = stlink_usb_usb_open,
+       .close = stlink_usb_usb_close,
+       .xfer_noerrcheck = stlink_usb_usb_xfer_noerrcheck,
+       .read_trace = stlink_usb_usb_read_trace,
+};
+
+static struct stlink_backend_s stlink_tcp_backend = {
+       .open = stlink_tcp_open,
+       .close = stlink_tcp_close,
+       .xfer_noerrcheck = stlink_tcp_xfer_noerrcheck,
+       .read_trace = stlink_tcp_read_trace,
+};
+
+static int stlink_open(struct hl_interface_param_s *param, enum stlink_mode mode, void **fd)
+{
+       struct stlink_usb_handle_s *h;
+
+       LOG_DEBUG("stlink_open");
+
+       h = calloc(1, sizeof(struct stlink_usb_handle_s));
+
+       if (h == 0) {
+               LOG_DEBUG("malloc failed");
+               return ERROR_FAIL;
+       }
+
+       h->st_mode = mode;
+
+       for (unsigned i = 0; param->vid[i]; i++) {
+               LOG_DEBUG("transport: %d vid: 0x%04x pid: 0x%04x serial: %s",
+                         h->st_mode, param->vid[i], param->pid[i],
+                         param->serial ? param->serial : "");
+       }
+
+       if (param->use_stlink_tcp)
+               h->backend = &stlink_tcp_backend;
+       else
+               h->backend = &stlink_usb_backend;
+
+       if (stlink_usb_open(h, param) != ERROR_OK)
+               goto error_open;
+
+       /* check if mode is supported */
+       int err = ERROR_OK;
+
+       switch (h->st_mode) {
+               case STLINK_MODE_DEBUG_SWD:
+                       if (h->version.jtag_api == STLINK_JTAG_API_V1)
+                               err = ERROR_FAIL;
+                       /* fall-through */
+               case STLINK_MODE_DEBUG_JTAG:
+                       if (h->version.jtag == 0)
+                               err = ERROR_FAIL;
+                       break;
+               case STLINK_MODE_DEBUG_SWIM:
+                       if (h->version.swim == 0)
+                               err = ERROR_FAIL;
+                       break;
+               default:
+                       err = ERROR_FAIL;
+                       break;
+       }
+
+       if (err != ERROR_OK) {
+               LOG_ERROR("mode (transport) not supported by device");
+               goto error_open;
+       }
+
+       /* initialize the debug hardware */
+       err = stlink_usb_init_mode(h, param->connect_under_reset, param->initial_interface_speed);
+
+       if (err != ERROR_OK) {
+               LOG_ERROR("init mode failed (unable to connect to the target)");
+               goto error_open;
+       }
+
+       if (h->st_mode == STLINK_MODE_DEBUG_SWIM) {
+               err = stlink_swim_enter(h);
+               if (err != ERROR_OK) {
+                       LOG_ERROR("stlink_swim_enter_failed (unable to connect to the target)");
+                       goto error_open;
+               }
+               *fd = h;
+               h->max_mem_packet = STLINK_DATA_SIZE;
+               return ERROR_OK;
+       }
+
+       /* set max_mem_packet if it was not set by the low-level interface */
+       if (h->max_mem_packet == 0) {
+               /* get cpuid, so we can determine the max page size
+                * start with a safe default */
+               h->max_mem_packet = (1 << 10);
+
+               uint8_t buffer[4];
+               stlink_usb_open_ap(h, 0);
+               err = stlink_usb_read_mem32(h, CPUID, 4, buffer);
+               if (err == ERROR_OK) {
+                       uint32_t cpuid = le_to_h_u32(buffer);
+                       int i = (cpuid >> 4) & 0xf;
+                       if (i == 4 || i == 3) {
+                               /* Cortex-M3/M4 has 4096 bytes autoincrement range */
+                               h->max_mem_packet = (1 << 12);
+                       }
+               }
+
+               LOG_DEBUG("Using TAR autoincrement: %" PRIu32, h->max_mem_packet);
+       }
+
+       *fd = h;
+
+       return ERROR_OK;
+
+error_open:
+       stlink_close(h);
+       return ERROR_FAIL;
+}
+
+static int stlink_usb_hl_open(struct hl_interface_param_s *param, void **fd)
+{
+       return stlink_open(param, stlink_get_mode(param->transport), fd);
+}
+
+static int stlink_config_trace(void *handle, bool enabled,
+               enum tpiu_pin_protocol pin_protocol, uint32_t port_size,
+               unsigned int *trace_freq, unsigned int traceclkin_freq,
+               uint16_t *prescaler)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       if (!(h->version.flags & STLINK_F_HAS_TRACE)) {
+               LOG_ERROR("The attached ST-LINK version doesn't support trace");
+               return ERROR_FAIL;
+       }
+
+       if (!enabled) {
+               stlink_usb_trace_disable(h);
+               return ERROR_OK;
+       }
+
+       assert(trace_freq);
+       assert(prescaler);
+
+       if (pin_protocol != TPIU_PIN_PROTOCOL_ASYNC_UART) {
+               LOG_ERROR("The attached ST-LINK version doesn't support this trace mode");
+               return ERROR_FAIL;
+       }
+
+       unsigned int max_trace_freq = (h->version.stlink == 3) ?
+                       STLINK_V3_TRACE_MAX_HZ : STLINK_TRACE_MAX_HZ;
+
+       /* Only concern ourselves with the frequency if the STlink is processing it. */
+       if (*trace_freq > max_trace_freq) {
+               LOG_ERROR("ST-LINK doesn't support SWO frequency higher than %u",
+                         max_trace_freq);
+               return ERROR_FAIL;
+       }
+
+       if (!*trace_freq)
+               *trace_freq = max_trace_freq;
+
+       unsigned int presc = (traceclkin_freq + *trace_freq / 2) / *trace_freq;
+       if (presc == 0 || presc > TPIU_ACPR_MAX_SWOSCALER + 1) {
+               LOG_ERROR("SWO frequency is not suitable. Please choose a different "
+                       "frequency.");
+               return ERROR_FAIL;
+       }
+
+       /* Probe's UART speed must be within 3% of the TPIU's SWO baud rate. */
+       unsigned int max_deviation = (traceclkin_freq * 3) / 100;
+       if (presc * *trace_freq < traceclkin_freq - max_deviation ||
+                       presc * *trace_freq > traceclkin_freq + max_deviation) {
+               LOG_ERROR("SWO frequency is not suitable. Please choose a different "
+                       "frequency.");
+               return ERROR_FAIL;
+       }
+
+       *prescaler = presc;
+
+       stlink_usb_trace_disable(h);
+
+       h->trace.source_hz = *trace_freq;
+
+       return stlink_usb_trace_enable(h);
+}
+
+/** */
+static int stlink_usb_init_access_port(void *handle, unsigned char ap_num)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       assert(handle);
+
+       if (!(h->version.flags & STLINK_F_HAS_AP_INIT))
+               return ERROR_COMMAND_NOTFOUND;
+
+       LOG_DEBUG_IO("init ap_num = %d", ap_num);
+       stlink_usb_init_buffer(handle, h->rx_ep, 16);
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_INIT_AP;
+       h->cmdbuf[h->cmdidx++] = ap_num;
+
+       return stlink_usb_xfer_errcheck(handle, h->databuf, 2);
+}
+
+/** */
+static int stlink_usb_close_access_port(void *handle, unsigned char ap_num)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       assert(handle);
+
+       if (!(h->version.flags & STLINK_F_HAS_AP_INIT))
+               return ERROR_COMMAND_NOTFOUND;
+
+       LOG_DEBUG_IO("close ap_num = %d", ap_num);
+       stlink_usb_init_buffer(handle, h->rx_ep, 16);
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_CLOSE_AP_DBG;
+       h->cmdbuf[h->cmdidx++] = ap_num;
+
+       /* ignore incorrectly returned error on bogus FW */
+       if (h->version.flags & STLINK_F_FIX_CLOSE_AP)
+               return stlink_usb_xfer_errcheck(handle, h->databuf, 2);
+       else
+               return stlink_usb_xfer_noerrcheck(handle, h->databuf, 2);
+
+}
+
+/** */
+static int stlink_read_dap_register(void *handle, unsigned short dap_port,
+                       unsigned short addr, uint32_t *val)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int retval;
+
+       assert(handle);
+
+       if (!(h->version.flags & STLINK_F_HAS_DAP_REG))
+               return ERROR_COMMAND_NOTFOUND;
+
+       stlink_usb_init_buffer(handle, h->rx_ep, 16);
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_READ_DAP_REG;
+       h_u16_to_le(&h->cmdbuf[2], dap_port);
+       h_u16_to_le(&h->cmdbuf[4], addr);
+
+       retval = stlink_usb_xfer_errcheck(handle, h->databuf, 8);
+       *val = le_to_h_u32(h->databuf + 4);
+       LOG_DEBUG_IO("dap_port_read = %d, addr =  0x%x, value = 0x%" PRIx32, dap_port, addr, *val);
+       return retval;
+}
+
+/** */
+static int stlink_write_dap_register(void *handle, unsigned short dap_port,
+                       unsigned short addr, uint32_t val)
+{
+       struct stlink_usb_handle_s *h = handle;
+
+       assert(handle);
+
+       if (!(h->version.flags & STLINK_F_HAS_DAP_REG))
+               return ERROR_COMMAND_NOTFOUND;
+
+       LOG_DEBUG_IO("dap_write port = %d, addr = 0x%x, value = 0x%" PRIx32, dap_port, addr, val);
+       stlink_usb_init_buffer(handle, h->rx_ep, 16);
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_COMMAND;
+       h->cmdbuf[h->cmdidx++] = STLINK_DEBUG_APIV2_WRITE_DAP_REG;
+       h_u16_to_le(&h->cmdbuf[2], dap_port);
+       h_u16_to_le(&h->cmdbuf[4], addr);
+       h_u32_to_le(&h->cmdbuf[6], val);
+       return stlink_usb_xfer_errcheck(handle, h->databuf, 2);
+}
+
+/** */
+struct hl_layout_api_s stlink_usb_layout_api = {
+       /** */
+       .open = stlink_usb_hl_open,
+       /** */
+       .close = stlink_close,
+       /** */
+       .idcode = stlink_usb_idcode,
+       /** */
+       .state = stlink_usb_state,
+       /** */
+       .reset = stlink_usb_reset,
+       /** */
+       .assert_srst = stlink_usb_assert_srst,
+       /** */
+       .run = stlink_usb_run,
+       /** */
+       .halt = stlink_usb_halt,
+       /** */
+       .step = stlink_usb_step,
+       /** */
+       .read_regs = stlink_usb_read_regs,
+       /** */
+       .read_reg = stlink_usb_read_reg,
+       /** */
+       .write_reg = stlink_usb_write_reg,
+       /** */
+       .read_mem = stlink_usb_read_mem,
+       /** */
+       .write_mem = stlink_usb_write_mem,
+       /** */
+       .write_debug_reg = stlink_usb_write_debug_reg,
+       /** */
+       .override_target = stlink_usb_override_target,
+       /** */
+       .speed = stlink_speed,
+       /** */
+       .config_trace = stlink_config_trace,
+       /** */
+       .poll_trace = stlink_usb_trace_read,
+};
+
+/*****************************************************************************
+ * DAP direct interface
+ */
+
+static struct stlink_usb_handle_s *stlink_dap_handle;
+static struct hl_interface_param_s stlink_dap_param;
+static DECLARE_BITMAP(opened_ap, DP_APSEL_MAX + 1);
+static int stlink_dap_error = ERROR_OK;
+
+static int stlink_dap_op_queue_dp_read(struct adiv5_dap *dap, unsigned reg,
+               uint32_t *data);
+
+/** */
+static int stlink_dap_record_error(int error)
+{
+       if (stlink_dap_error == ERROR_OK)
+               stlink_dap_error = error;
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_dap_get_and_clear_error(void)
+{
+       int retval = stlink_dap_error;
+       stlink_dap_error = ERROR_OK;
+       return retval;
+}
+
+static int stlink_usb_open_ap(void *handle, unsigned short apsel)
+{
+       struct stlink_usb_handle_s *h = handle;
+       int retval;
+
+       /* nothing to do on old versions */
+       if (!(h->version.flags & STLINK_F_HAS_AP_INIT))
+               return ERROR_OK;
+
+       if (apsel > DP_APSEL_MAX)
+               return ERROR_FAIL;
+
+       if (test_bit(apsel, opened_ap))
+               return ERROR_OK;
+
+       retval = stlink_usb_init_access_port(h, apsel);
+       if (retval != ERROR_OK)
+               return retval;
+
+       LOG_DEBUG("AP %d enabled", apsel);
+       set_bit(apsel, opened_ap);
+       return ERROR_OK;
+}
+
+static int stlink_dap_open_ap(unsigned short apsel)
+{
+       return stlink_usb_open_ap(stlink_dap_handle, apsel);
+}
+
+/** */
+static int stlink_dap_closeall_ap(void)
+{
+       int retval, apsel;
+
+       /* nothing to do on old versions */
+       if (!(stlink_dap_handle->version.flags & STLINK_F_HAS_AP_INIT))
+               return ERROR_OK;
+
+       for (apsel = 0; apsel <= DP_APSEL_MAX; apsel++) {
+               if (!test_bit(apsel, opened_ap))
+                       continue;
+               retval = stlink_usb_close_access_port(stlink_dap_handle, apsel);
+               if (retval != ERROR_OK)
+                       return retval;
+               clear_bit(apsel, opened_ap);
+       }
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_dap_reinit_interface(void)
+{
+       int retval;
+
+       /*
+        * On JTAG only, it should be enough to call stlink_usb_reset(). But on
+        * some firmware version it does not work as expected, and there is no
+        * equivalent for SWD.
+        * At least for now, to reset the interface quit from JTAG/SWD mode then
+        * select the mode again.
+        */
+
+       if (!stlink_dap_handle->reconnect_pending) {
+               stlink_dap_handle->reconnect_pending = true;
+               stlink_usb_mode_leave(stlink_dap_handle, stlink_dap_handle->st_mode);
+       }
+
+       retval = stlink_usb_mode_enter(stlink_dap_handle, stlink_dap_handle->st_mode);
+       if (retval != ERROR_OK)
+               return retval;
+
+       stlink_dap_handle->reconnect_pending = false;
+       /* on new FW, calling mode-leave closes all the opened AP; reopen them! */
+       if (stlink_dap_handle->version.flags & STLINK_F_HAS_AP_INIT)
+               for (int apsel = 0; apsel <= DP_APSEL_MAX; apsel++)
+                       if (test_bit(apsel, opened_ap)) {
+                               clear_bit(apsel, opened_ap);
+                               stlink_dap_open_ap(apsel);
+                       }
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_dap_op_connect(struct adiv5_dap *dap)
+{
+       uint32_t idcode;
+       int retval;
+
+       LOG_INFO("stlink_dap_op_connect(%sconnect)", dap->do_reconnect ? "re" : "");
+
+       /* Check if we should reset srst already when connecting, but not if reconnecting. */
+       if (!dap->do_reconnect) {
+               enum reset_types jtag_reset_config = jtag_get_reset_config();
+
+               if (jtag_reset_config & RESET_CNCT_UNDER_SRST) {
+                       if (jtag_reset_config & RESET_SRST_NO_GATING)
+                               adapter_assert_reset();
+                       else
+                               LOG_WARNING("\'srst_nogate\' reset_config option is required");
+               }
+       }
+
+       dap->do_reconnect = false;
+       dap_invalidate_cache(dap);
+
+       retval = dap_dp_init(dap);
+       if (retval != ERROR_OK) {
+               dap->do_reconnect = true;
+               return retval;
+       }
+
+       retval = stlink_usb_idcode(stlink_dap_handle, &idcode);
+       if (retval == ERROR_OK)
+               LOG_INFO("%s %#8.8" PRIx32,
+                       (stlink_dap_handle->st_mode == STLINK_MODE_DEBUG_JTAG) ? "JTAG IDCODE" : "SWD DPIDR",
+                       idcode);
+       else
+               dap->do_reconnect = true;
+
+       return retval;
+}
+
+/** */
+static int stlink_dap_check_reconnect(struct adiv5_dap *dap)
+{
+       int retval;
+
+       if (!dap->do_reconnect)
+               return ERROR_OK;
+
+       retval = stlink_dap_reinit_interface();
+       if (retval != ERROR_OK)
+               return retval;
+
+       return stlink_dap_op_connect(dap);
+}
+
+/** */
+static int stlink_dap_op_send_sequence(struct adiv5_dap *dap, enum swd_special_seq seq)
+{
+       /* Ignore the request */
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_dap_op_queue_dp_read(struct adiv5_dap *dap, unsigned reg,
+               uint32_t *data)
+{
+       uint32_t dummy;
+       int retval;
+
+       if (!(stlink_dap_handle->version.flags & STLINK_F_HAS_DPBANKSEL))
+               if (reg & 0x000000F0) {
+                       LOG_ERROR("Banked DP registers not supported in current STLink FW");
+                       return ERROR_COMMAND_NOTFOUND;
+               }
+
+       retval = stlink_dap_check_reconnect(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       data = data ? data : &dummy;
+       if (stlink_dap_handle->version.flags & STLINK_F_QUIRK_JTAG_DP_READ
+               && stlink_dap_handle->st_mode == STLINK_MODE_DEBUG_JTAG) {
+               /* Quirk required in JTAG. Read RDBUFF to get the data */
+               retval = stlink_read_dap_register(stlink_dap_handle,
+                                       STLINK_DEBUG_PORT_ACCESS, reg, &dummy);
+               if (retval == ERROR_OK)
+                       retval = stlink_read_dap_register(stlink_dap_handle,
+                                               STLINK_DEBUG_PORT_ACCESS, DP_RDBUFF, data);
+       } else {
+               retval = stlink_read_dap_register(stlink_dap_handle,
+                                       STLINK_DEBUG_PORT_ACCESS, reg, data);
+       }
+
+       return stlink_dap_record_error(retval);
+}
+
+/** */
+static int stlink_dap_op_queue_dp_write(struct adiv5_dap *dap, unsigned reg,
+               uint32_t data)
+{
+       int retval;
+
+       if (!(stlink_dap_handle->version.flags & STLINK_F_HAS_DPBANKSEL))
+               if (reg & 0x000000F0) {
+                       LOG_ERROR("Banked DP registers not supported in current STLink FW");
+                       return ERROR_COMMAND_NOTFOUND;
+               }
+
+       if (reg == DP_SELECT && (data & DP_SELECT_DPBANK) != 0) {
+               /* ignored if STLINK_F_HAS_DPBANKSEL, not properly managed otherwise */
+               LOG_DEBUG("Ignoring DPBANKSEL while write SELECT");
+               data &= ~DP_SELECT_DPBANK;
+       }
+
+       retval = stlink_dap_check_reconnect(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       /* ST-Link does not like that we set CORUNDETECT */
+       if (reg == DP_CTRL_STAT)
+               data &= ~CORUNDETECT;
+
+       retval = stlink_write_dap_register(stlink_dap_handle,
+                               STLINK_DEBUG_PORT_ACCESS, reg, data);
+       return stlink_dap_record_error(retval);
+}
+
+/** */
+static int stlink_dap_op_queue_ap_read(struct adiv5_ap *ap, unsigned reg,
+               uint32_t *data)
+{
+       struct adiv5_dap *dap = ap->dap;
+       uint32_t dummy;
+       int retval;
+
+       retval = stlink_dap_check_reconnect(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       if (reg != AP_REG_IDR) {
+               retval = stlink_dap_open_ap(ap->ap_num);
+               if (retval != ERROR_OK)
+                       return retval;
+       }
+       data = data ? data : &dummy;
+       retval = stlink_read_dap_register(stlink_dap_handle, ap->ap_num, reg,
+                                data);
+       dap->stlink_flush_ap_write = false;
+       return stlink_dap_record_error(retval);
+}
+
+/** */
+static int stlink_dap_op_queue_ap_write(struct adiv5_ap *ap, unsigned reg,
+               uint32_t data)
+{
+       struct adiv5_dap *dap = ap->dap;
+       int retval;
+
+       retval = stlink_dap_check_reconnect(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       retval = stlink_dap_open_ap(ap->ap_num);
+       if (retval != ERROR_OK)
+               return retval;
+
+       retval = stlink_write_dap_register(stlink_dap_handle, ap->ap_num, reg,
+                               data);
+       dap->stlink_flush_ap_write = true;
+       return stlink_dap_record_error(retval);
+}
+
+/** */
+static int stlink_dap_op_queue_ap_abort(struct adiv5_dap *dap, uint8_t *ack)
+{
+       LOG_WARNING("stlink_dap_op_queue_ap_abort()");
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_dap_op_run(struct adiv5_dap *dap)
+{
+       uint32_t ctrlstat, pwrmask;
+       int retval, saved_retval;
+
+       /* Here no LOG_DEBUG. This is called continuously! */
+
+       /*
+        * ST-Link returns immediately after a DAP write, without waiting for it
+        * to complete.
+        * Run a dummy read to DP_RDBUFF, as suggested in
+        * http://infocenter.arm.com/help/topic/com.arm.doc.faqs/ka16363.html
+        */
+       if (dap->stlink_flush_ap_write) {
+               dap->stlink_flush_ap_write = false;
+               retval = stlink_dap_op_queue_dp_read(dap, DP_RDBUFF, NULL);
+               if (retval != ERROR_OK) {
+                       dap->do_reconnect = true;
+                       return retval;
+               }
+       }
+
+       saved_retval = stlink_dap_get_and_clear_error();
+
+       retval = stlink_dap_op_queue_dp_read(dap, DP_CTRL_STAT, &ctrlstat);
+       if (retval != ERROR_OK) {
+               dap->do_reconnect = true;
+               return retval;
+       }
+       retval = stlink_dap_get_and_clear_error();
+       if (retval != ERROR_OK) {
+               LOG_ERROR("Fail reading CTRL/STAT register. Force reconnect");
+               dap->do_reconnect = true;
+               return retval;
+       }
+
+       if (ctrlstat & SSTICKYERR) {
+               if (stlink_dap_handle->st_mode == STLINK_MODE_DEBUG_JTAG)
+                       retval = stlink_dap_op_queue_dp_write(dap, DP_CTRL_STAT,
+                                       ctrlstat & (dap->dp_ctrl_stat | SSTICKYERR));
+               else
+                       retval = stlink_dap_op_queue_dp_write(dap, DP_ABORT, STKERRCLR);
+               if (retval != ERROR_OK) {
+                       dap->do_reconnect = true;
+                       return retval;
+               }
+               retval = stlink_dap_get_and_clear_error();
+               if (retval != ERROR_OK) {
+                       dap->do_reconnect = true;
+                       return retval;
+               }
+       }
+
+       /* check for power lost */
+       pwrmask = dap->dp_ctrl_stat & (CDBGPWRUPREQ | CSYSPWRUPREQ);
+       if ((ctrlstat & pwrmask) != pwrmask)
+               dap->do_reconnect = true;
+
+       return saved_retval;
+}
+
+/** */
+static void stlink_dap_op_quit(struct adiv5_dap *dap)
+{
+       int retval;
+
+       retval = stlink_dap_closeall_ap();
+       if (retval != ERROR_OK)
+               LOG_ERROR("Error closing APs");
+}
+
+static int stlink_swim_op_srst(void)
+{
+       return stlink_swim_generate_rst(stlink_dap_handle);
+}
+
+static int stlink_swim_op_read_mem(uint32_t addr, uint32_t size,
+                                                                  uint32_t count, uint8_t *buffer)
+{
+       int retval;
+       uint32_t bytes_remaining;
+
+       LOG_DEBUG_IO("read at 0x%08" PRIx32 " len %" PRIu32 "*0x%08" PRIx32, addr, size, count);
+       count *= size;
+
+       while (count) {
+               bytes_remaining = (count > STLINK_DATA_SIZE) ? STLINK_DATA_SIZE : count;
+               retval = stlink_swim_readbytes(stlink_dap_handle, addr, bytes_remaining, buffer);
+               if (retval != ERROR_OK)
+                       return retval;
+
+               buffer += bytes_remaining;
+               addr += bytes_remaining;
+               count -= bytes_remaining;
+       }
+
+       return ERROR_OK;
+}
+
+static int stlink_swim_op_write_mem(uint32_t addr, uint32_t size,
+                                                                       uint32_t count, const uint8_t *buffer)
+{
+       int retval;
+       uint32_t bytes_remaining;
+
+       LOG_DEBUG_IO("write at 0x%08" PRIx32 " len %" PRIu32 "*0x%08" PRIx32, addr, size, count);
+       count *= size;
+
+       while (count) {
+               bytes_remaining = (count > STLINK_DATA_SIZE) ? STLINK_DATA_SIZE : count;
+               retval = stlink_swim_writebytes(stlink_dap_handle, addr, bytes_remaining, buffer);
+               if (retval != ERROR_OK)
+                       return retval;
+
+               buffer += bytes_remaining;
+               addr += bytes_remaining;
+               count -= bytes_remaining;
+       }
+
+       return ERROR_OK;
+}
+
+static int stlink_swim_op_reconnect(void)
+{
+       int retval;
+
+       retval = stlink_usb_mode_enter(stlink_dap_handle, STLINK_MODE_DEBUG_SWIM);
+       if (retval != ERROR_OK)
+               return retval;
+
+       return stlink_swim_resync(stlink_dap_handle);
+}
+
+static int stlink_dap_config_trace(bool enabled,
+               enum tpiu_pin_protocol pin_protocol, uint32_t port_size,
+               unsigned int *trace_freq, unsigned int traceclkin_freq,
+               uint16_t *prescaler)
+{
+       return stlink_config_trace(stlink_dap_handle, enabled, pin_protocol,
+                                                          port_size, trace_freq, traceclkin_freq,
+                                                          prescaler);
+}
+
+static int stlink_dap_trace_read(uint8_t *buf, size_t *size)
+{
+       return stlink_usb_trace_read(stlink_dap_handle, buf, size);
+}
+
+/** */
+COMMAND_HANDLER(stlink_dap_serial_command)
+{
+       LOG_DEBUG("stlink_dap_serial_command");
+
+       if (CMD_ARGC != 1) {
+               LOG_ERROR("Expected exactly one argument for \"st-link serial <serial-number>\".");
+               return ERROR_COMMAND_SYNTAX_ERROR;
+       }
+
+       if (stlink_dap_param.serial) {
+               LOG_WARNING("Command \"st-link serial\" already used. Replacing previous value");
+               free((void *)stlink_dap_param.serial);
+       }
+
+       stlink_dap_param.serial = strdup(CMD_ARGV[0]);
+       return ERROR_OK;
+}
+
+/** */
+COMMAND_HANDLER(stlink_dap_vid_pid)
+{
+       unsigned int i, max_usb_ids = HLA_MAX_USB_IDS;
+
+       if (CMD_ARGC > max_usb_ids * 2) {
+               LOG_WARNING("ignoring extra IDs in vid_pid "
+                       "(maximum is %d pairs)", max_usb_ids);
+               CMD_ARGC = max_usb_ids * 2;
+       }
+       if (CMD_ARGC < 2 || (CMD_ARGC & 1)) {
+               LOG_WARNING("incomplete vid_pid configuration directive");
+               return ERROR_COMMAND_SYNTAX_ERROR;
+       }
+       for (i = 0; i < CMD_ARGC; i += 2) {
+               COMMAND_PARSE_NUMBER(u16, CMD_ARGV[i], stlink_dap_param.vid[i / 2]);
+               COMMAND_PARSE_NUMBER(u16, CMD_ARGV[i + 1], stlink_dap_param.pid[i / 2]);
+       }
+
+       /* null termination */
+       stlink_dap_param.vid[i / 2] = stlink_dap_param.pid[i / 2] = 0;
+
+       return ERROR_OK;
+}
+
+/** */
+COMMAND_HANDLER(stlink_dap_backend_command)
+{
+       /* default values */
+       bool use_stlink_tcp = false;
+       uint16_t stlink_tcp_port = 7184;
+
+       if (CMD_ARGC == 0 || CMD_ARGC > 2)
+               return ERROR_COMMAND_SYNTAX_ERROR;
+       else if (strcmp(CMD_ARGV[0], "usb") == 0) {
+               if (CMD_ARGC > 1)
+                       return ERROR_COMMAND_SYNTAX_ERROR;
+               /* else use_stlink_tcp = false (already the case ) */
+       } else if (strcmp(CMD_ARGV[0], "tcp") == 0) {
+               use_stlink_tcp = true;
+               if (CMD_ARGC == 2)
+                       COMMAND_PARSE_NUMBER(u16, CMD_ARGV[1], stlink_tcp_port);
+       } else
+               return ERROR_COMMAND_SYNTAX_ERROR;
+
+       stlink_dap_param.use_stlink_tcp = use_stlink_tcp;
+       stlink_dap_param.stlink_tcp_port = stlink_tcp_port;
+
+       return ERROR_OK;
+}
+
+/** */
+static const struct command_registration stlink_dap_subcommand_handlers[] = {
+       {
+               .name = "serial",
+               .handler = stlink_dap_serial_command,
+               .mode = COMMAND_CONFIG,
+               .help = "set the serial number of the adapter",
+               .usage = "<serial_number>",
+       },
+       {
+               .name = "vid_pid",
+               .handler = stlink_dap_vid_pid,
+               .mode = COMMAND_CONFIG,
+               .help = "USB VID and PID of the adapter",
+               .usage = "(vid pid)+",
+       },
+       {
+               .name = "backend",
+               .handler = &stlink_dap_backend_command,
+               .mode = COMMAND_CONFIG,
+               .help = "select which ST-Link backend to use",
+               .usage = "usb | tcp [port]",
+       },
+       COMMAND_REGISTRATION_DONE
+};
+
+/** */
+static const struct command_registration stlink_dap_command_handlers[] = {
+       {
+               .name = "st-link",
+               .mode = COMMAND_ANY,
+               .help = "perform st-link management",
+               .chain = stlink_dap_subcommand_handlers,
+               .usage = "",
+       },
+       COMMAND_REGISTRATION_DONE
+};
+
+/** */
+static int stlink_dap_init(void)
+{
+       enum reset_types jtag_reset_config = jtag_get_reset_config();
+       enum stlink_mode mode;
+       int retval;
+
+       LOG_DEBUG("stlink_dap_init()");
+
+       if (jtag_reset_config & RESET_CNCT_UNDER_SRST) {
+               if (jtag_reset_config & RESET_SRST_NO_GATING)
+                       stlink_dap_param.connect_under_reset = true;
+               else
+                       LOG_WARNING("\'srst_nogate\' reset_config option is required");
+       }
+
+       if (transport_is_dapdirect_swd())
+               mode = STLINK_MODE_DEBUG_SWD;
+       else if (transport_is_dapdirect_jtag())
+               mode = STLINK_MODE_DEBUG_JTAG;
+       else if (transport_is_swim())
+               mode = STLINK_MODE_DEBUG_SWIM;
+       else {
+               LOG_ERROR("Unsupported transport");
+               return ERROR_FAIL;
+       }
+
+       retval = stlink_open(&stlink_dap_param, mode, (void **)&stlink_dap_handle);
+       if (retval != ERROR_OK)
+               return retval;
+
+       if ((mode != STLINK_MODE_DEBUG_SWIM) &&
+               !(stlink_dap_handle->version.flags & STLINK_F_HAS_DAP_REG)) {
+               LOG_ERROR("ST-Link version does not support DAP direct transport");
+               return ERROR_FAIL;
+       }
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_dap_quit(void)
+{
+       LOG_DEBUG("stlink_dap_quit()");
+
+       free((void *)stlink_dap_param.serial);
+       stlink_dap_param.serial = NULL;
+
+       return stlink_close(stlink_dap_handle);
+}
+
+/** */
+static int stlink_dap_reset(int req_trst, int req_srst)
+{
+       LOG_DEBUG("stlink_dap_reset(%d)", req_srst);
+       return stlink_usb_assert_srst(stlink_dap_handle,
+               req_srst ? STLINK_DEBUG_APIV2_DRIVE_NRST_LOW
+                                : STLINK_DEBUG_APIV2_DRIVE_NRST_HIGH);
+}
+
+/** */
+static int stlink_dap_speed(int speed)
+{
+       if (speed == 0) {
+               LOG_ERROR("RTCK not supported. Set nonzero adapter_khz.");
+               return ERROR_JTAG_NOT_IMPLEMENTED;
+       }
+
+       stlink_dap_param.initial_interface_speed = speed;
+       stlink_speed(stlink_dap_handle, speed, false);
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_dap_khz(int khz, int *jtag_speed)
+{
+       if (khz == 0) {
+               LOG_ERROR("RCLK not supported");
+               return ERROR_FAIL;
+       }
+
+       *jtag_speed = stlink_speed(stlink_dap_handle, khz, true);
+       return ERROR_OK;
+}
+
+/** */
+static int stlink_dap_speed_div(int speed, int *khz)
+{
+       *khz = speed;
+       return ERROR_OK;
+}
+
+static const struct dap_ops stlink_dap_ops = {
+       .connect = stlink_dap_op_connect,
+       .send_sequence = stlink_dap_op_send_sequence,
+       .queue_dp_read = stlink_dap_op_queue_dp_read,
+       .queue_dp_write = stlink_dap_op_queue_dp_write,
+       .queue_ap_read = stlink_dap_op_queue_ap_read,
+       .queue_ap_write = stlink_dap_op_queue_ap_write,
+       .queue_ap_abort = stlink_dap_op_queue_ap_abort,
+       .run = stlink_dap_op_run,
+       .sync = NULL, /* optional */
+       .quit = stlink_dap_op_quit, /* optional */
+};
+
+static const struct swim_driver stlink_swim_ops = {
+       .srst = stlink_swim_op_srst,
+       .read_mem = stlink_swim_op_read_mem,
+       .write_mem = stlink_swim_op_write_mem,
+       .reconnect = stlink_swim_op_reconnect,
+};
+
+static const char *const stlink_dap_transport[] = { "dapdirect_swd", "dapdirect_jtag", "swim", NULL };
+
+struct adapter_driver stlink_dap_adapter_driver = {
+       .name = "st-link",
+       .transports = stlink_dap_transport,
+       .commands = stlink_dap_command_handlers,
+
+       .init = stlink_dap_init,
+       .quit = stlink_dap_quit,
+       .reset = stlink_dap_reset,
+       .speed = stlink_dap_speed,
+       .khz = stlink_dap_khz,
+       .speed_div = stlink_dap_speed_div,
+       .config_trace = stlink_dap_config_trace,
+       .poll_trace = stlink_dap_trace_read,
+
+       .dap_jtag_ops = &stlink_dap_ops,
+       .dap_swd_ops = &stlink_dap_ops,
+       .swim_ops = &stlink_swim_ops,
 };