jtag_command_t -> struct jtag_command
[fw/openocd] / src / jtag / jlink.c
index 44a1ad6d723e402fbb15cbd6fd27b7c40cd18f15..9677f0e80d54ade44c075a45188a78e7c5081895 100644 (file)
 #include "config.h"
 #endif
 
-#include "replacements.h"
-
-#include "jtag.h"
+#include "interface.h"
+#include "commands.h"
 
 #include <usb.h>
-#include <string.h>
 
-#include "log.h"
 
 #define VID 0x1366
 #define PID 0x0101
 #define JLINK_WRITE_ENDPOINT   0x02
 #define JLINK_READ_ENDPOINT            0x81
 
+static unsigned int jlink_write_ep = JLINK_WRITE_ENDPOINT;
+static unsigned int jlink_read_ep = JLINK_READ_ENDPOINT;
+static unsigned int jlink_hw_jtag_version = 2;
+
 #define JLINK_USB_TIMEOUT              1000
 
 // See Section 1.3.2 of the Segger JLink USB protocol manual
+/* 2048 is the max value we can use here */
+//#define JLINK_TAP_BUFFER_SIZE 2048
+#define JLINK_TAP_BUFFER_SIZE 256
+//#define JLINK_TAP_BUFFER_SIZE 384
+
 #define JLINK_IN_BUFFER_SIZE                   2048
-#define JLINK_OUT_BUFFER_SIZE                  2048
+#define JLINK_OUT_BUFFER_SIZE                  2*2048 + 4
 #define JLINK_EMU_RESULT_BUFFER_SIZE   64
 
 /* Global USB buffers */
-static u8 usb_in_buffer[JLINK_IN_BUFFER_SIZE];
-static u8 usb_out_buffer[JLINK_OUT_BUFFER_SIZE];
-static u8 usb_emu_result_buffer[JLINK_EMU_RESULT_BUFFER_SIZE];
+static uint8_t usb_in_buffer[JLINK_IN_BUFFER_SIZE];
+static uint8_t usb_out_buffer[JLINK_OUT_BUFFER_SIZE];
+static uint8_t usb_emu_result_buffer[JLINK_EMU_RESULT_BUFFER_SIZE];
 
 /* Constants for JLink command */
-#define EMU_CMD_VERSION     0x01
-#define EMU_CMD_SET_SPEED   0x05
-#define EMU_CMD_GET_STATE   0x07
-#define EMU_CMD_HW_JTAG3    0xcf
-#define EMU_CMD_HW_RESET0   0xdc
-#define EMU_CMD_HW_RESET1   0xdd
-#define EMU_CMD_HW_TRST0    0xde
-#define EMU_CMD_HW_TRST1    0xdf
+#define EMU_CMD_VERSION                0x01
+#define EMU_CMD_SET_SPEED              0x05
+#define EMU_CMD_GET_STATE              0x07
+#define EMU_CMD_HW_CLOCK                       0xc8
+#define EMU_CMD_HW_TMS0                        0xc9
+#define EMU_CMD_HW_TMS1                        0xca
+#define EMU_CMD_HW_JTAG2               0xce
+#define EMU_CMD_HW_JTAG3               0xcf
+#define EMU_CMD_GET_MAX_MEM_BLOCK      0xd4
+#define EMU_CMD_HW_RESET0              0xdc
+#define EMU_CMD_HW_RESET1              0xdd
+#define EMU_CMD_HW_TRST0               0xde
+#define EMU_CMD_HW_TRST1               0xdf
+#define EMU_CMD_GET_CAPS               0xe8
+#define EMU_CMD_GET_HW_VERSION 0xf0
+
+/* bits return from EMU_CMD_GET_CAPS */
+#define EMU_CAP_GET_HW_VERSION         1
+#define EMU_CAP_GET_MAX_BLOCK_SIZE     11
 
 /* max speed 12MHz v5.0 jlink */
 #define JLINK_MAX_SPEED 12000
@@ -76,15 +93,16 @@ static int jlink_quit(void);
 
 /* CLI command handler functions */
 static int jlink_handle_jlink_info_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
+static int jlink_handle_jlink_hw_jtag_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc);
 
 /* Queue command functions */
 static void jlink_end_state(tap_state_t state);
 static void jlink_state_move(void);
 static void jlink_path_move(int num_states, tap_state_t *path);
 static void jlink_runtest(int num_cycles);
-static void jlink_scan(int ir_scan, enum scan_type type, u8 *buffer, int scan_size, scan_command_t *command);
+static void jlink_scan(bool ir_scan, enum scan_type type, uint8_t *buffer, int scan_size, struct scan_command *command);
 static void jlink_reset(int trst, int srst);
-static void jlink_simple_command(u8 command);
+static void jlink_simple_command(uint8_t command);
 static int jlink_get_status(void);
 
 /* J-Link tap buffer functions */
@@ -92,34 +110,35 @@ static void jlink_tap_init(void);
 static int jlink_tap_execute(void);
 static void jlink_tap_ensure_space(int scans, int bits);
 static void jlink_tap_append_step(int tms, int tdi);
-static void jlink_tap_append_scan(int length, u8 *buffer, scan_command_t *command);
+static void jlink_tap_append_scan(int length, uint8_t *buffer, struct scan_command *command);
 
 /* Jlink lowlevel functions */
-typedef struct jlink_jtag
-{
+struct jlink {
        struct usb_dev_handle* usb_handle;
-} jlink_jtag_t;
+};
 
-static jlink_jtag_t *jlink_usb_open(void);
-static void jlink_usb_close(jlink_jtag_t *jlink_jtag);
-static int jlink_usb_message(jlink_jtag_t *jlink_jtag, int out_length, int in_length);
-static int jlink_usb_write(jlink_jtag_t *jlink_jtag, int out_length);
-static int jlink_usb_read(jlink_jtag_t *jlink_jtag, int expected_size);
-static int jlink_usb_read_emu_result(jlink_jtag_t *jlink_jtag);
+static struct jlink *jlink_usb_open(void);
+static void jlink_usb_close(struct jlink *jlink);
+static int jlink_usb_message(struct jlink *jlink, int out_length, int in_length);
+static int jlink_usb_write(struct jlink *jlink, int out_length);
+static int jlink_usb_read(struct jlink *jlink, int expected_size);
+static int jlink_usb_read_emu_result(struct jlink *jlink);
 
 /* helper functions */
 static int jlink_get_version_info(void);
 
 #ifdef _DEBUG_USB_COMMS_
-static void jlink_debug_buffer(u8 *buffer, int length);
+static void jlink_debug_buffer(uint8_t *buffer, int length);
 #endif
 
-static jlink_jtag_t* jlink_jtag_handle;
+static enum tap_state jlink_last_state = TAP_RESET;
+
+static struct jlink* jlink_handle;
 
 /***************************************************************************/
 /* External interface implementation */
 
-jtag_interface_t jlink_interface =
+struct jtag_interface jlink_interface =
 {
        .name = "jlink",
        .execute_queue = jlink_execute_queue,
@@ -131,38 +150,26 @@ jtag_interface_t jlink_interface =
        .quit = jlink_quit
 };
 
-static void jlink_execute_end_state(jtag_command_t *cmd)
-{
-       DEBUG_JTAG_IO("end_state: %i", cmd->cmd.end_state->end_state);
-
-       if (cmd->cmd.end_state->end_state != TAP_INVALID)
-               jlink_end_state(cmd->cmd.end_state->end_state);
-}
-
-static void jlink_execute_runtest(jtag_command_t *cmd)
+static void jlink_execute_runtest(struct jtag_command *cmd)
 {
        DEBUG_JTAG_IO("runtest %i cycles, end in %i",
                        cmd->cmd.runtest->num_cycles,
                        cmd->cmd.runtest->end_state);
 
-       if (cmd->cmd.runtest->end_state != TAP_INVALID)
-               jlink_end_state(cmd->cmd.runtest->end_state);
+       jlink_end_state(cmd->cmd.runtest->end_state);
 
        jlink_runtest(cmd->cmd.runtest->num_cycles);
 }
 
-static void jlink_execute_statemove(jtag_command_t *cmd)
+static void jlink_execute_statemove(struct jtag_command *cmd)
 {
        DEBUG_JTAG_IO("statemove end in %i", cmd->cmd.statemove->end_state);
 
-       if (cmd->cmd.statemove->end_state != TAP_INVALID)
-       {
-               jlink_end_state(cmd->cmd.statemove->end_state);
-       }
+       jlink_end_state(cmd->cmd.statemove->end_state);
        jlink_state_move();
 }
 
-static void jlink_execute_pathmove(jtag_command_t *cmd)
+static void jlink_execute_pathmove(struct jtag_command *cmd)
 {
        DEBUG_JTAG_IO("pathmove: %i states, end in %i",
                cmd->cmd.pathmove->num_states,
@@ -172,16 +179,15 @@ static void jlink_execute_pathmove(jtag_command_t *cmd)
                        cmd->cmd.pathmove->path);
 }
 
-static void jlink_execute_scan(jtag_command_t *cmd)
+static void jlink_execute_scan(struct jtag_command *cmd)
 {
        int scan_size;
        enum scan_type type;
-       u8 *buffer;
+       uint8_t *buffer;
 
-       DEBUG_JTAG_IO("scan end in %i", cmd->cmd.scan->end_state);
+       DEBUG_JTAG_IO("scan end in %s", tap_state_name(cmd->cmd.scan->end_state));
 
-       if (cmd->cmd.scan->end_state != TAP_INVALID)
-               jlink_end_state(cmd->cmd.scan->end_state);
+       jlink_end_state(cmd->cmd.scan->end_state);
 
        scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
        DEBUG_JTAG_IO("scan input, length = %d", scan_size);
@@ -194,31 +200,27 @@ static void jlink_execute_scan(jtag_command_t *cmd)
                        type, buffer, scan_size, cmd->cmd.scan);
 }
 
-static void jlink_execute_reset(jtag_command_t *cmd)
+static void jlink_execute_reset(struct jtag_command *cmd)
 {
        DEBUG_JTAG_IO("reset trst: %i srst %i",
                        cmd->cmd.reset->trst, cmd->cmd.reset->srst);
 
        jlink_tap_execute();
-
-       if (cmd->cmd.reset->trst == 1)
-               tap_set_state(TAP_RESET);
-
        jlink_reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
+       jlink_tap_execute();
 }
 
-static void jlink_execute_sleep(jtag_command_t *cmd)
+static void jlink_execute_sleep(struct jtag_command *cmd)
 {
        DEBUG_JTAG_IO("sleep %i", cmd->cmd.sleep->us);
        jlink_tap_execute();
        jtag_sleep(cmd->cmd.sleep->us);
 }
 
-static void jlink_execute_command(jtag_command_t *cmd)
+static void jlink_execute_command(struct jtag_command *cmd)
 {
        switch (cmd->type)
        {
-       case JTAG_END_STATE: jlink_execute_end_state(cmd); break;
        case JTAG_RUNTEST:   jlink_execute_runtest(cmd); break;
        case JTAG_STATEMOVE: jlink_execute_statemove(cmd); break;
        case JTAG_PATHMOVE:  jlink_execute_pathmove(cmd); break;
@@ -233,7 +235,7 @@ static void jlink_execute_command(jtag_command_t *cmd)
 
 static int jlink_execute_queue(void)
 {
-       jtag_command_t *cmd = jtag_command_queue;
+       struct jtag_command *cmd = jtag_command_queue;
 
        while (cmd != NULL)
        {
@@ -264,7 +266,7 @@ static int jlink_speed(int speed)
        usb_out_buffer[1] = (speed >> 0) & 0xff;
        usb_out_buffer[2] = (speed >> 8) & 0xff;
 
-       result = jlink_usb_write(jlink_jtag_handle, 3);
+       result = jlink_usb_write(jlink_handle, 3);
        if (result != 3)
        {
                LOG_ERROR("J-Link setting speed failed (%d)", result);
@@ -290,52 +292,71 @@ static int jlink_khz(int khz, int *jtag_speed)
 
 static int jlink_register_commands(struct command_context_s *cmd_ctx)
 {
-       register_command(cmd_ctx, NULL, "jlink_info", jlink_handle_jlink_info_command, COMMAND_EXEC,
+
+       register_command(cmd_ctx, NULL, "jlink_info",
+               &jlink_handle_jlink_info_command, COMMAND_EXEC,
                "query jlink info");
+       register_command(cmd_ctx, NULL, "jlink_hw_jtag",
+               &jlink_handle_jlink_hw_jtag_command, COMMAND_EXEC,
+               "set/get jlink hw jtag command version [2 | 3]");
        return ERROR_OK;
 }
 
 static int jlink_init(void)
 {
-       int check_cnt;
+       int i;
 
-       jlink_jtag_handle = jlink_usb_open();
+       jlink_handle = jlink_usb_open();
 
-       if (jlink_jtag_handle == 0)
+       if (jlink_handle == 0)
        {
                LOG_ERROR("Cannot find jlink Interface! Please check connection and permissions.");
                return ERROR_JTAG_INIT_FAILED;
        }
 
-       check_cnt = 0;
-       while (check_cnt < 3)
-       {
-               if (jlink_get_version_info() == ERROR_OK)
-               {
-                       /* attempt to get status */
-                       jlink_get_status();
-                       break;
-               }
+       /*
+        *  The next three instructions were added after discovering a problem while using an oscilloscope.  For the V8
+        *      SAM-ICE dongle (and likely other j-link device variants), the reset line to the target microprocessor was found to
+        *      cycle only intermittently during emulator startup (even after encountering the downstream reset instruction later
+        *      in the code).  This was found to create two issues:  1) In general it is a bad practice to not reset a CPU to a known
+        *      state when starting an emulator and 2) something critical happens inside the dongle when it does the first read
+        *      following a new USB session.  Keeping the processor in reset during the first read collecting version information
+        *      seems to prevent errant "J-Link command EMU_CMD_VERSION failed" issues.
+        */
 
-               check_cnt++;
-       }
+       LOG_INFO("J-Link initialization started / target CPU reset initiated");
+       jlink_simple_command(EMU_CMD_HW_TRST0);
+       jlink_simple_command(EMU_CMD_HW_RESET0);
+       usleep(1000);
+
+       jlink_hw_jtag_version = 2;
 
-       if (check_cnt == 3)
+       if (jlink_get_version_info() == ERROR_OK)
        {
-               LOG_INFO("J-Link initial read failed, don't worry");
+               /* attempt to get status */
+               jlink_get_status();
        }
 
        LOG_INFO("J-Link JTAG Interface ready");
 
        jlink_reset(0, 0);
+       jtag_sleep(3000);
        jlink_tap_init();
+       jlink_speed(jtag_get_speed());
+
+       /* v5/6 jlink seems to have an issue if the first tap move
+        * is not divisible by 8, so we send a TLR on first power up */
+       for (i = 0; i < 8; i++) {
+               jlink_tap_append_step(1, 0);
+       }
+       jlink_tap_execute();
 
        return ERROR_OK;
 }
 
 static int jlink_quit(void)
 {
-       jlink_usb_close(jlink_jtag_handle);
+       jlink_usb_close(jlink_handle);
        return ERROR_OK;
 }
 
@@ -360,9 +381,10 @@ static void jlink_state_move(void)
 {
        int i;
        int tms = 0;
-       u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
+       uint8_t tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
+       uint8_t tms_scan_bits = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
 
-       for (i = 0; i < 7; i++)
+       for (i = 0; i < tms_scan_bits; i++)
        {
                tms = (tms_scan >> i) & 1;
                jlink_tap_append_step(tms, 0);
@@ -403,11 +425,14 @@ static void jlink_runtest(int num_cycles)
 
        tap_state_t saved_end_state = tap_get_end_state();
 
+       jlink_tap_ensure_space(1,num_cycles + 16);
+
        /* only do a state_move when we're not already in IDLE */
        if (tap_get_state() != TAP_IDLE)
        {
                jlink_end_state(TAP_IDLE);
                jlink_state_move();
+//             num_cycles--;
        }
 
        /* execute num_cycles */
@@ -424,11 +449,11 @@ static void jlink_runtest(int num_cycles)
        }
 }
 
-static void jlink_scan(int ir_scan, enum scan_type type, u8 *buffer, int scan_size, scan_command_t *command)
+static void jlink_scan(bool ir_scan, enum scan_type type, uint8_t *buffer, int scan_size, struct scan_command *command)
 {
        tap_state_t saved_end_state;
 
-       jlink_tap_ensure_space(1, scan_size + 8);
+       jlink_tap_ensure_space(1, scan_size + 16);
 
        saved_end_state = tap_get_end_state();
 
@@ -463,34 +488,31 @@ static void jlink_reset(int trst, int srst)
        if (srst == 0)
        {
                jlink_simple_command(EMU_CMD_HW_RESET1);
-               jlink_end_state(TAP_RESET);
-               jlink_state_move();
        }
-       else if (srst == 1)
+       if (srst == 1)
        {
                jlink_simple_command(EMU_CMD_HW_RESET0);
        }
 
-       if (trst == 0)
+       if (trst == 1)
        {
-               jlink_simple_command(EMU_CMD_HW_TRST1);
-               jlink_end_state(TAP_RESET);
-               jlink_state_move();
+               jlink_simple_command(EMU_CMD_HW_TRST0);
        }
-       else if (trst == 1)
+
+       if (trst == 0)
        {
-               jlink_simple_command(EMU_CMD_HW_TRST0);
+               jlink_simple_command(EMU_CMD_HW_TRST1);
        }
 }
 
-static void jlink_simple_command(u8 command)
+static void jlink_simple_command(uint8_t command)
 {
        int result;
 
        DEBUG_JTAG_IO("0x%02x", command);
 
        usb_out_buffer[0] = command;
-       result = jlink_usb_write(jlink_jtag_handle, 1);
+       result = jlink_usb_write(jlink_handle, 1);
 
        if (result != 1)
        {
@@ -504,7 +526,7 @@ static int jlink_get_status(void)
 
        jlink_simple_command(EMU_CMD_GET_STATE);
 
-       result = jlink_usb_read(jlink_jtag_handle, 8);
+       result = jlink_usb_read(jlink_handle, 8);
        if (result != 8)
        {
                LOG_ERROR("J-Link command EMU_CMD_GET_STATE failed (%d)\n", result);
@@ -527,30 +549,84 @@ static int jlink_get_version_info(void)
 {
        int result;
        int len;
+       uint32_t jlink_caps, jlink_max_size;
 
        /* query hardware version */
        jlink_simple_command(EMU_CMD_VERSION);
 
-       result = jlink_usb_read(jlink_jtag_handle, 2);
+       result = jlink_usb_read(jlink_handle, 2);
        if (2 != result)
        {
-               LOG_ERROR("J-Link command EMU_CMD_VERSION failed (%d)\n",
-                               result);
+               LOG_ERROR("J-Link command EMU_CMD_VERSION failed (%d)\n", result);
                return ERROR_JTAG_DEVICE_ERROR;
        }
 
        len = buf_get_u32(usb_in_buffer, 0, 16);
-       result = jlink_usb_read(jlink_jtag_handle, len);
+       if (len > JLINK_IN_BUFFER_SIZE)
+       {
+               LOG_ERROR("J-Link command EMU_CMD_VERSION impossible return length 0x%0x", len);
+               len = JLINK_IN_BUFFER_SIZE;
+       }
+
+       result = jlink_usb_read(jlink_handle, len);
        if (result != len)
        {
-               LOG_ERROR("J-Link command EMU_CMD_VERSION failed (%d)\n",
-                               result);
+               LOG_ERROR("J-Link command EMU_CMD_VERSION failed (%d)\n", result);
                return ERROR_JTAG_DEVICE_ERROR;
        }
 
        usb_in_buffer[result] = 0;
        LOG_INFO("%s", (char *)usb_in_buffer);
 
+       /* query hardware capabilities */
+       jlink_simple_command(EMU_CMD_GET_CAPS);
+
+       result = jlink_usb_read(jlink_handle, 4);
+       if (4 != result)
+       {
+               LOG_ERROR("J-Link command EMU_CMD_GET_CAPS failed (%d)\n", result);
+               return ERROR_JTAG_DEVICE_ERROR;
+       }
+
+       jlink_caps = buf_get_u32(usb_in_buffer, 0, 32);
+       LOG_INFO("JLink caps 0x%x", (unsigned)jlink_caps);
+
+       if (jlink_caps & (1 << EMU_CAP_GET_HW_VERSION))
+       {
+               /* query hardware version */
+               jlink_simple_command(EMU_CMD_GET_HW_VERSION);
+
+               result = jlink_usb_read(jlink_handle, 4);
+               if (4 != result)
+               {
+                       LOG_ERROR("J-Link command EMU_CMD_GET_HW_VERSION failed (%d)\n", result);
+                       return ERROR_JTAG_DEVICE_ERROR;
+               }
+
+               uint32_t jlink_hw_version = buf_get_u32(usb_in_buffer, 0, 32);
+               uint32_t major_revision = (jlink_hw_version / 10000) % 100;
+               if (major_revision >= 5)
+                       jlink_hw_jtag_version = 3;
+
+               LOG_INFO("JLink hw version %i", (int)jlink_hw_version);
+       }
+
+       if (jlink_caps & (1 << EMU_CAP_GET_MAX_BLOCK_SIZE))
+       {
+               /* query hardware maximum memory block */
+               jlink_simple_command(EMU_CMD_GET_MAX_MEM_BLOCK);
+
+               result = jlink_usb_read(jlink_handle, 4);
+               if (4 != result)
+               {
+                       LOG_ERROR("J-Link command EMU_CMD_GET_MAX_MEM_BLOCK failed (%d)\n", result);
+                       return ERROR_JTAG_DEVICE_ERROR;
+               }
+
+               jlink_max_size = buf_get_u32(usb_in_buffer, 0, 32);
+               LOG_INFO("JLink max mem block %i", (int)jlink_max_size);
+       }
+
        return ERROR_OK;
 }
 
@@ -565,31 +641,50 @@ static int jlink_handle_jlink_info_command(struct command_context_s *cmd_ctx, ch
        return ERROR_OK;
 }
 
+static int jlink_handle_jlink_hw_jtag_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
+{
+       switch (argc) {
+       case 0:
+               command_print(cmd_ctx, "jlink hw jtag  %i", jlink_hw_jtag_version);
+               break;
+       case 1: {
+               int request_version = atoi(args[0]);
+               switch (request_version) {
+               case 2: case 3:
+                       jlink_hw_jtag_version = request_version;
+                       break;
+               default:
+                       return ERROR_COMMAND_SYNTAX_ERROR;
+               }
+               break;
+       }
+       default:
+               return ERROR_COMMAND_SYNTAX_ERROR;
+       }
+
+       return ERROR_OK;
+}
+
 /***************************************************************************/
 /* J-Link tap functions */
 
-/* 2048 is the max value we can use here */
-#define JLINK_TAP_BUFFER_SIZE 2048
 
-static unsigned tap_length;
-static u8 tms_buffer[JLINK_TAP_BUFFER_SIZE];
-static u8 tdi_buffer[JLINK_TAP_BUFFER_SIZE];
-static u8 tdo_buffer[JLINK_TAP_BUFFER_SIZE];
+static unsigned tap_length = 0;
+static uint8_t tms_buffer[JLINK_TAP_BUFFER_SIZE];
+static uint8_t tdi_buffer[JLINK_TAP_BUFFER_SIZE];
+static uint8_t tdo_buffer[JLINK_TAP_BUFFER_SIZE];
 
-typedef struct
-{
+struct pending_scan_result {
        int first;      /* First bit position in tdo_buffer to read */
        int length; /* Number of bits to read */
-       scan_command_t *command; /* Corresponding scan command */
-       u8 *buffer;
-} pending_scan_result_t;
+       struct scan_command *command; /* Corresponding scan command */
+       uint8_t *buffer;
+};
 
 #define MAX_PENDING_SCAN_RESULTS 256
 
 static int pending_scan_results_length;
-static pending_scan_result_t pending_scan_results_buffer[MAX_PENDING_SCAN_RESULTS];
-
-static int last_tms;
+static struct pending_scan_result pending_scan_results_buffer[MAX_PENDING_SCAN_RESULTS];
 
 static void jlink_tap_init(void)
 {
@@ -600,7 +695,7 @@ static void jlink_tap_init(void)
 static void jlink_tap_ensure_space(int scans, int bits)
 {
        int available_scans = MAX_PENDING_SCAN_RESULTS - pending_scan_results_length;
-       int available_bits = JLINK_TAP_BUFFER_SIZE * 8 - tap_length;
+       int available_bits = JLINK_TAP_BUFFER_SIZE * 8 - tap_length - 32;
 
        if (scans > available_scans || bits > available_bits)
        {
@@ -610,17 +705,23 @@ static void jlink_tap_ensure_space(int scans, int bits)
 
 static void jlink_tap_append_step(int tms, int tdi)
 {
-       last_tms = tms;
        int index = tap_length / 8;
 
        if (index >= JLINK_TAP_BUFFER_SIZE)
        {
                LOG_ERROR("jlink_tap_append_step: overflow");
+               *(uint32_t *)0xFFFFFFFF = 0;
                exit(-1);
        }
 
        int bit_index = tap_length % 8;
-       u8 bit = 1 << bit_index;
+       uint8_t bit = 1 << bit_index;
+
+       // we do not pad TMS, so be sure to initialize all bits
+       if (0 == bit_index)
+       {
+               tms_buffer[index] = tdi_buffer[index] = 0;
+       }
 
        if (tms)
                tms_buffer[index] |= bit;
@@ -635,9 +736,9 @@ static void jlink_tap_append_step(int tms, int tdi)
        tap_length++;
 }
 
-static void jlink_tap_append_scan(int length, u8 *buffer, scan_command_t *command)
+static void jlink_tap_append_scan(int length, uint8_t *buffer, struct scan_command *command)
 {
-       pending_scan_result_t *pending_scan_result =
+       struct pending_scan_result *pending_scan_result =
                &pending_scan_results_buffer[pending_scan_results_length];
        int i;
 
@@ -648,8 +749,8 @@ static void jlink_tap_append_scan(int length, u8 *buffer, scan_command_t *comman
 
        for (i = 0; i < length; i++)
        {
-               int tms = i < length - 1 ? 0 : 1;
-               int tdi = buffer[i / 8] & (1 << (i % 8));
+               int tms = (i < (length - 1)) ? 0 : 1;
+               int tdi = (buffer[i / 8] & (1 << (i % 8))) != 0;
                jlink_tap_append_step(tms, tdi);
        }
        pending_scan_results_length++;
@@ -660,60 +761,50 @@ static void jlink_tap_append_scan(int length, u8 *buffer, scan_command_t *comman
 static int jlink_tap_execute(void)
 {
        int byte_length;
-       int tms_offset;
-       int tdi_offset;
        int i;
        int result;
 
        if (!tap_length)
                return ERROR_OK;
 
-       /* Pad last byte so that tap_length is divisible by 8 */
-       while (tap_length % 8 != 0)
+       /* JLink returns an extra NULL in packet when size of in message is a multiple of 64, creates problems with usb comms */
+       /* WARNING This will interfere with tap state counting */
+       while ((TAP_SCAN_BYTES(tap_length)%64) == 0)
        {
-               /* More of the last TMS value keeps us in the same state,
-                * analogous to free-running JTAG interfaces. */
-               jlink_tap_append_step(last_tms, 0);
+               jlink_tap_append_step((tap_get_state() == TAP_RESET)?1:0, 0);
        }
 
-       byte_length = tap_length / 8;
+       // number of full bytes (plus one if some would be left over)
+       byte_length = TAP_SCAN_BYTES(tap_length);
 
-       usb_out_buffer[0] = EMU_CMD_HW_JTAG3;
+       bool use_jtag3 = jlink_hw_jtag_version >= 3;
+       usb_out_buffer[0] = use_jtag3 ? EMU_CMD_HW_JTAG3 : EMU_CMD_HW_JTAG2;
        usb_out_buffer[1] = 0;
        usb_out_buffer[2] = (tap_length >> 0) & 0xff;
        usb_out_buffer[3] = (tap_length >> 8) & 0xff;
+       memcpy(usb_out_buffer + 4, tms_buffer, byte_length);
+       memcpy(usb_out_buffer + 4 + byte_length, tdi_buffer, byte_length);
 
-       tms_offset = 4;
-       for (i = 0; i < byte_length; i++)
-       {
-               usb_out_buffer[tms_offset + i] = tms_buffer[i];
-       }
-
-       tdi_offset = tms_offset + byte_length;
-       for (i = 0; i < byte_length; i++)
-       {
-               usb_out_buffer[tdi_offset + i] = tdi_buffer[i];
-       }
-
-       result = jlink_usb_message(jlink_jtag_handle, 4 + 2 * byte_length, byte_length);
+       jlink_last_state = jtag_debug_state_machine(tms_buffer, tdi_buffer,
+                       tap_length, jlink_last_state);
 
+       result = jlink_usb_message(jlink_handle, 4 + 2 * byte_length, byte_length);
        if (result != byte_length)
        {
-               LOG_ERROR("jlink_tap_execute, wrong result %d (expected %d)",
-                               result, byte_length);
+               LOG_ERROR("jlink_tap_execute, wrong result %d (expected %d)", result, byte_length);
+               jlink_tap_init();
                return ERROR_JTAG_QUEUE_FAILED;
        }
 
-       for (i = 0; i < byte_length; i++)
-               tdo_buffer[i] = usb_in_buffer[i];
+       memcpy(tdo_buffer, usb_in_buffer, byte_length);
 
        for (i = 0; i < pending_scan_results_length; i++)
        {
-               pending_scan_result_t *pending_scan_result = &pending_scan_results_buffer[i];
-               u8 *buffer = pending_scan_result->buffer;
+               struct pending_scan_result *pending_scan_result = &pending_scan_results_buffer[i];
+               uint8_t *buffer = pending_scan_result->buffer;
                int length = pending_scan_result->length;
                int first = pending_scan_result->first;
-               scan_command_t *command = pending_scan_result->command;
+               struct scan_command *command = pending_scan_result->command;
 
                /* Copy to buffer */
                buf_set_buf(tdo_buffer, first, buffer, 0, length);
@@ -721,7 +812,7 @@ static int jlink_tap_execute(void)
                DEBUG_JTAG_IO("pending scan result, length = %d", length);
 
 #ifdef _DEBUG_USB_COMMS_
-               jlink_debug_buffer(buffer, byte_length);
+               jlink_debug_buffer(buffer, TAP_SCAN_BYTES(length));
 #endif
 
                if (jtag_read_buffer(buffer, command) != ERROR_OK)
@@ -737,52 +828,122 @@ static int jlink_tap_execute(void)
        }
 
        jlink_tap_init();
-
        return ERROR_OK;
 }
 
-/*****************************************************************************/
-/* JLink USB low-level functions */
-
-static jlink_jtag_t* jlink_usb_open()
+static struct usb_device* find_jlink_device(void)
 {
        struct usb_bus *busses;
        struct usb_bus *bus;
        struct usb_device *dev;
 
-       jlink_jtag_t *result;
-
-       result = (jlink_jtag_t*) malloc(sizeof(jlink_jtag_t));
-
-       usb_init();
        usb_find_busses();
        usb_find_devices();
 
        busses = usb_get_busses();
 
-       /* find jlink_jtag device in usb bus */
+       /* find jlink device in usb bus */
 
        for (bus = busses; bus; bus = bus->next)
        {
                for (dev = bus->devices; dev; dev = dev->next)
                {
-                       if ((dev->descriptor.idVendor == VID) && (dev->descriptor.idProduct == PID))
-                       {
-                               result->usb_handle = usb_open(dev);
+                       if ((dev->descriptor.idVendor == VID) && (dev->descriptor.idProduct == PID)) {
+                               return dev;
+                       }
+               }
+       }
 
-                               /* usb_set_configuration required under win32 */
-                               usb_set_configuration(result->usb_handle, dev->config[0].bConfigurationValue);
-                               usb_claim_interface(result->usb_handle, 0);
+       return NULL;
+}
+
+/*****************************************************************************/
+/* JLink USB low-level functions */
+
+static struct jlink* jlink_usb_open()
+{
+       struct usb_device *dev;
+
+       struct jlink *result;
+
+       result = (struct jlink*) malloc(sizeof(struct jlink));
+
+       usb_init();
+
+       if ((dev = find_jlink_device()) == NULL) {
+               free(result);
+               return NULL;
+       }
+
+       result->usb_handle = usb_open(dev);
+
+       if (result->usb_handle)
+       {
+
+               /* BE ***VERY CAREFUL*** ABOUT MAKING CHANGES IN THIS AREA!!!!!!!!!!!
+                * The behavior of libusb is not completely consistent across Windows, Linux, and Mac OS X platforms.  The actions taken
+                * in the following compiler conditionals may not agree with published documentation for libusb, but were found
+                * to be necessary through trials and tribulations.  Even little tweaks can break one or more platforms, so if you do make changes
+                * test them carefully on all platforms before committing them!
+                */
+
+#if IS_WIN32 == 0
+
+               usb_reset(result->usb_handle);
+
+#if IS_DARWIN == 0
+
+               int timeout = 5;
+
+               /* reopen jlink after usb_reset
+                * on win32 this may take a second or two to re-enumerate */
+               while ((dev = find_jlink_device()) == NULL)
+               {
+                       usleep(1000);
+                       timeout--;
+                       if (!timeout) {
+                               break;
+                       }
+               }
+
+               if (dev == NULL)
+               {
+                       free(result);
+                       return NULL;
+               }
+
+               result->usb_handle = usb_open(dev);
+#endif
+
+#endif
+
+               if (result->usb_handle)
+               {
+                       /* usb_set_configuration required under win32 */
+                       usb_set_configuration(result->usb_handle, dev->config[0].bConfigurationValue);
+                       usb_claim_interface(result->usb_handle, 0);
 
 #if 0
-                               /*
-                                * This makes problems under Mac OS X. And is not needed
-                                * under Windows. Hopefully this will not break a linux build
-                                */
-                               usb_set_altinterface(result->usb_handle, 0);
+                       /*
+                        * This makes problems under Mac OS X. And is not needed
+                        * under Windows. Hopefully this will not break a linux build
+                        */
+                       usb_set_altinterface(result->usb_handle, 0);
 #endif
-                               return result;
+                       struct usb_interface *iface = dev->config->interface;
+                       struct usb_interface_descriptor *desc = iface->altsetting;
+                       for (int i = 0; i < desc->bNumEndpoints; i++)
+                       {
+                               uint8_t epnum = desc->endpoint[i].bEndpointAddress;
+                               bool is_input = epnum & 0x80;
+                               LOG_DEBUG("usb ep %s %02x", is_input ? "in" : "out", epnum);
+                               if (is_input)
+                                       jlink_read_ep = epnum;
+                               else
+                                       jlink_write_ep = epnum;
                        }
+
+                       return result;
                }
        }
 
@@ -790,19 +951,18 @@ static jlink_jtag_t* jlink_usb_open()
        return NULL;
 }
 
-static void jlink_usb_close(jlink_jtag_t *jlink_jtag)
+static void jlink_usb_close(struct jlink *jlink)
 {
-       usb_close(jlink_jtag->usb_handle);
-       free(jlink_jtag);
+       usb_close(jlink->usb_handle);
+       free(jlink);
 }
 
 /* Send a message and receive the reply. */
-static int jlink_usb_message(jlink_jtag_t *jlink_jtag, int out_length, int in_length)
+static int jlink_usb_message(struct jlink *jlink, int out_length, int in_length)
 {
        int result;
-       int result2;
 
-       result = jlink_usb_write(jlink_jtag, out_length);
+       result = jlink_usb_write(jlink, out_length);
        if (result != out_length)
        {
                LOG_ERROR("usb_bulk_write failed (requested=%d, result=%d)",
@@ -810,23 +970,33 @@ static int jlink_usb_message(jlink_jtag_t *jlink_jtag, int out_length, int in_le
                return ERROR_JTAG_DEVICE_ERROR;
        }
 
-       result = jlink_usb_read(jlink_jtag, in_length);
-       if ((result != in_length) && (result != in_length + 1))
+       result = jlink_usb_read(jlink, in_length);
+       if ((result != in_length) && (result != (in_length + 1)))
        {
                LOG_ERROR("usb_bulk_read failed (requested=%d, result=%d)",
                                in_length, result);
                return ERROR_JTAG_DEVICE_ERROR;
        }
 
+       if (jlink_hw_jtag_version < 3)
+               return result;
+
+       int result2 = ERROR_OK;
        if (result == in_length)
        {
                /* Must read the result from the EMU too */
-               result2 = jlink_usb_read_emu_result(jlink_jtag);
+               result2 = jlink_usb_read_emu_result(jlink);
                if (1 != result2)
                {
-                       LOG_ERROR("jlink_usb_read_emu_result failed "
-                               "(requested=1, result=%d)", result2);
-                       return ERROR_JTAG_DEVICE_ERROR;
+                       LOG_ERROR("jlink_usb_read_emu_result retried requested = 1, result=%d, in_length=%i", result2,in_length);
+                       /* Try again once, should only happen if (in_length%64 == 0) */
+                       result2 = jlink_usb_read_emu_result(jlink);
+                       if (1 != result2)
+                       {
+                               LOG_ERROR("jlink_usb_read_emu_result failed "
+                                       "(requested = 1, result=%d)", result2);
+                               return ERROR_JTAG_DEVICE_ERROR;
+                       }
                }
 
                /* Check the result itself */
@@ -853,28 +1023,33 @@ static int usb_bulk_with_retries(
                usb_dev_handle *dev, int ep,
                char *bytes, int size, int timeout)
 {
-       int rc = 0, tries = 3, this_size;
+       int tries = 3, count = 0;
 
-       while (tries && size) {
-
-               this_size = f(dev, ep, bytes, size, timeout);
-               if (this_size > 0) {
-                       
-                       size -= this_size;
-                       rc += this_size;
-                       bytes += this_size;
-
-               } else
-                       tries --;
+       while (tries && (count < size))
+       {
+               int result = f(dev, ep, bytes + count, size - count, timeout);
+               if (result > 0)
+                       count += result;
+               else if ((-ETIMEDOUT != result) || !--tries)
+                       return result;
        }
-       return rc;
+       return count;
 }
+
+static int wrap_usb_bulk_write(usb_dev_handle *dev, int ep,
+                              char *buff, int size, int timeout)
+{
+       /* usb_bulk_write() takes const char *buff */
+       return usb_bulk_write(dev, ep, buff, size, timeout);
+}
+
 static inline int usb_bulk_write_ex(usb_dev_handle *dev, int ep,
                char *bytes, int size, int timeout)
 {
-       return usb_bulk_with_retries(&usb_bulk_write,
+       return usb_bulk_with_retries(&wrap_usb_bulk_write,
                        dev, ep, bytes, size, timeout);
 }
+
 static inline int usb_bulk_read_ex(usb_dev_handle *dev, int ep,
                char *bytes, int size, int timeout)
 {
@@ -883,17 +1058,17 @@ static inline int usb_bulk_read_ex(usb_dev_handle *dev, int ep,
 }
 
 /* Write data from out_buffer to USB. */
-static int jlink_usb_write(jlink_jtag_t *jlink_jtag, int out_length)
+static int jlink_usb_write(struct jlink *jlink, int out_length)
 {
        int result;
 
        if (out_length > JLINK_OUT_BUFFER_SIZE)
        {
-               LOG_ERROR("jlink_jtag_write illegal out_length=%d (max=%d)", out_length, JLINK_OUT_BUFFER_SIZE);
+               LOG_ERROR("jlink_write illegal out_length=%d (max=%d)", out_length, JLINK_OUT_BUFFER_SIZE);
                return -1;
        }
 
-       result = usb_bulk_write_ex(jlink_jtag->usb_handle, JLINK_WRITE_ENDPOINT,
+       result = usb_bulk_write_ex(jlink->usb_handle, jlink_write_ep,
                (char *)usb_out_buffer, out_length, JLINK_USB_TIMEOUT);
 
        DEBUG_JTAG_IO("jlink_usb_write, out_length = %d, result = %d", out_length, result);
@@ -905,9 +1080,9 @@ static int jlink_usb_write(jlink_jtag_t *jlink_jtag, int out_length)
 }
 
 /* Read data from USB into in_buffer. */
-static int jlink_usb_read(jlink_jtag_t *jlink_jtag, int expected_size)
+static int jlink_usb_read(struct jlink *jlink, int expected_size)
 {
-       int result = usb_bulk_read_ex(jlink_jtag->usb_handle, JLINK_READ_ENDPOINT,
+       int result = usb_bulk_read_ex(jlink->usb_handle, jlink_read_ep,
                (char *)usb_in_buffer, expected_size, JLINK_USB_TIMEOUT);
 
        DEBUG_JTAG_IO("jlink_usb_read, result = %d", result);
@@ -919,9 +1094,9 @@ static int jlink_usb_read(jlink_jtag_t *jlink_jtag, int expected_size)
 }
 
 /* Read the result from the previous EMU cmd into result_buffer. */
-static int jlink_usb_read_emu_result(jlink_jtag_t *jlink_jtag)
+static int jlink_usb_read_emu_result(struct jlink *jlink)
 {
-       int result = usb_bulk_read_ex(jlink_jtag->usb_handle, JLINK_READ_ENDPOINT,
+       int result = usb_bulk_read_ex(jlink->usb_handle, jlink_read_ep,
                (char *)usb_emu_result_buffer, 1 /* JLINK_EMU_RESULT_BUFFER_SIZE */,
                JLINK_USB_TIMEOUT);
 
@@ -936,7 +1111,7 @@ static int jlink_usb_read_emu_result(jlink_jtag_t *jlink_jtag)
 #ifdef _DEBUG_USB_COMMS_
 #define BYTES_PER_LINE  16
 
-static void jlink_debug_buffer(u8 *buffer, int length)
+static void jlink_debug_buffer(uint8_t *buffer, int length)
 {
        char line[81];
        char s[4];
@@ -955,3 +1130,4 @@ static void jlink_debug_buffer(u8 *buffer, int length)
        }
 }
 #endif
+