target/adi_v5_swd: fix SWD multidrop
[fw/openocd] / src / target / adi_v5_swd.c
index 5a3570d536f457734f084fcbb0e408ef78c9afa0..bd85eb217ab54cb18d86e2d0df5e4e42ef1b9d4d 100644 (file)
@@ -1,21 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
 /***************************************************************************
  *
  *   Copyright (C) 2010 by David Brownell
- *
- *   This program is free software; you can redistribute it and/or modify
- *   it under the terms of the GNU General Public License as published by
- *   the Free Software Foundation; either version 2 of the License, or
- *   (at your option) any later version.
- *
- *   This program is distributed in the hope that it will be useful,
- *   but WITHOUT ANY WARRANTY; without even the implied warranty of
- *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *   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.,
- *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  ***************************************************************************/
 
 /**
@@ -31,6 +18,7 @@
  * for details, see "ARM IHI 0031A"
  * ARM Debug Interface v5 Architecture Specification
  * especially section 5.3 for SWD protocol
+ * and "ARM IHI 0074C" ARM Debug Interface Architecture Specification ADIv6.0
  *
  * On many chips (most current Cortex-M3 parts) SWD is a run-time alternative
  * to JTAG.  Boards may support one or both.  There are also SWD-only chips,
 
 #include <jtag/swd.h>
 
+/* for debug, set do_sync to true to force synchronous transfers */
+static bool do_sync;
 
+static struct adiv5_dap *swd_multidrop_selected_dap;
 
-static int swd_queue_dp_read(struct adiv5_dap *dap, unsigned reg,
-               uint32_t *data)
+
+static int swd_queue_dp_write_inner(struct adiv5_dap *dap, unsigned int reg,
+               uint32_t data);
+
+
+static int swd_send_sequence(struct adiv5_dap *dap, enum swd_special_seq seq)
 {
-       // REVISIT status return vs ack ...
-       return swd->read_reg(swd_cmd(true,  false, reg), data);
+       const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
+       assert(swd);
+
+       return swd->switch_seq(seq);
 }
 
-static int swd_queue_idcode_read(struct adiv5_dap *dap,
-               uint8_t *ack, uint32_t *data)
+static void swd_finish_read(struct adiv5_dap *dap)
 {
-       int status = swd_queue_dp_read(dap, DP_IDCODE, data);
-       if (status < 0)
-               return status;
-       *ack = status;
-       // ??
-       return ERROR_OK;
+       const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
+       if (dap->last_read) {
+               swd->read_reg(swd_cmd(true, false, DP_RDBUFF), dap->last_read, 0);
+               dap->last_read = NULL;
+       }
 }
 
-static int (swd_queue_dp_write)(struct adiv5_dap *dap, unsigned reg,
-               uint32_t data)
+static void swd_clear_sticky_errors(struct adiv5_dap *dap)
+{
+       const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
+       assert(swd);
+
+       swd->write_reg(swd_cmd(false, false, DP_ABORT),
+               STKCMPCLR | STKERRCLR | WDERRCLR | ORUNERRCLR, 0);
+}
+
+static int swd_run_inner(struct adiv5_dap *dap)
+{
+       const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
+       int retval;
+
+       retval = swd->run();
+
+       if (retval != ERROR_OK) {
+               /* fault response */
+               dap->do_reconnect = true;
+       }
+
+       return retval;
+}
+
+static inline int check_sync(struct adiv5_dap *dap)
 {
-       // REVISIT status return vs ack ...
-       return swd->write_reg(swd_cmd(false,  false, reg), data);
+       return do_sync ? swd_run_inner(dap) : ERROR_OK;
 }
 
+/** Select the DP register bank matching bits 7:4 of reg. */
+static int swd_queue_dp_bankselect(struct adiv5_dap *dap, unsigned int reg)
+{
+       /* Only register address 0 and 4 are banked. */
+       if ((reg & 0xf) > 4)
+               return ERROR_OK;
+
+       uint64_t sel = (reg & 0x000000F0) >> 4;
+       if (dap->select != DP_SELECT_INVALID)
+               sel |= dap->select & ~0xfULL;
 
-static int (swd_queue_ap_read)(struct adiv5_dap *dap, unsigned reg,
+       if (sel == dap->select)
+               return ERROR_OK;
+
+       dap->select = sel;
+
+       int retval = swd_queue_dp_write_inner(dap, DP_SELECT, (uint32_t)sel);
+       if (retval != ERROR_OK)
+               dap->select = DP_SELECT_INVALID;
+
+       return retval;
+}
+
+static int swd_queue_dp_read_inner(struct adiv5_dap *dap, unsigned int reg,
                uint32_t *data)
 {
-       // REVISIT  APSEL ...
-       // REVISIT status return ...
-       return swd->read_reg(swd_cmd(true,  true, reg), data);
+       const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
+       assert(swd);
+
+       int retval = swd_queue_dp_bankselect(dap, reg);
+       if (retval != ERROR_OK)
+               return retval;
+
+       swd->read_reg(swd_cmd(true, false, reg), data, 0);
+
+       return check_sync(dap);
 }
 
-static int (swd_queue_ap_write)(struct adiv5_dap *dap, unsigned reg,
+static int swd_queue_dp_write_inner(struct adiv5_dap *dap, unsigned int reg,
                uint32_t data)
 {
-       // REVISIT  APSEL ...
-       // REVISIT status return ...
-       return swd->write_reg(swd_cmd(false,  true, reg), data);
+       int retval;
+       const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
+       assert(swd);
+
+       swd_finish_read(dap);
+
+       if (reg == DP_SELECT) {
+               dap->select = data & (DP_SELECT_APSEL | DP_SELECT_APBANK | DP_SELECT_DPBANK);
+
+               swd->write_reg(swd_cmd(false, false, reg), data, 0);
+
+               retval = check_sync(dap);
+               if (retval != ERROR_OK)
+                       dap->select = DP_SELECT_INVALID;
+
+               return retval;
+       }
+
+       retval = swd_queue_dp_bankselect(dap, reg);
+       if (retval != ERROR_OK)
+               return retval;
+
+       swd->write_reg(swd_cmd(false, false, reg), data, 0);
+
+       return check_sync(dap);
 }
 
-static int (swd_queue_ap_abort)(struct adiv5_dap *dap, uint8_t *ack)
+
+static int swd_multidrop_select_inner(struct adiv5_dap *dap, uint32_t *dpidr_ptr,
+               uint32_t *dlpidr_ptr, bool clear_sticky)
 {
-       return ERROR_FAIL;
+       int retval;
+       uint32_t dpidr, dlpidr;
+
+       assert(dap_is_multidrop(dap));
+
+       swd_send_sequence(dap, LINE_RESET);
+       /* From ARM IHI 0074C ADIv6.0, chapter B4.3.3 "Connection and line reset
+        * sequence":
+        * - line reset sets DP_SELECT_DPBANK to zero;
+        * - read of DP_DPIDR takes the connection out of reset;
+        * - write of DP_TARGETSEL keeps the connection in reset;
+        * - other accesses return protocol error (SWDIO not driven by target).
+        *
+        * Read DP_DPIDR to get out of reset. Initialize dap->select to zero to
+        * skip the write to DP_SELECT, avoiding the protocol error. Set again
+        * dap->select to DP_SELECT_INVALID because the rest of the register is
+        * unknown after line reset.
+        */
+       dap->select = 0;
+
+       retval = swd_queue_dp_write_inner(dap, DP_TARGETSEL, dap->multidrop_targetsel);
+       if (retval != ERROR_OK)
+               return retval;
+
+       retval = swd_queue_dp_read_inner(dap, DP_DPIDR, &dpidr);
+       if (retval != ERROR_OK)
+               return retval;
+
+       if (clear_sticky) {
+               /* Clear all sticky errors (including ORUN) */
+               swd_clear_sticky_errors(dap);
+       } else {
+               /* Ideally just clear ORUN flag which is set by reset */
+               retval = swd_queue_dp_write_inner(dap, DP_ABORT, ORUNERRCLR);
+               if (retval != ERROR_OK)
+                       return retval;
+       }
+
+       dap->select = DP_SELECT_INVALID;
+
+       retval = swd_queue_dp_read_inner(dap, DP_DLPIDR, &dlpidr);
+       if (retval != ERROR_OK)
+               return retval;
+
+       retval = swd_run_inner(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       if ((dpidr & DP_DPIDR_VERSION_MASK) < (2UL << DP_DPIDR_VERSION_SHIFT)) {
+               LOG_INFO("Read DPIDR 0x%08" PRIx32
+                                " has version < 2. A non multidrop capable device connected?",
+                                dpidr);
+               return ERROR_FAIL;
+       }
+
+       /* TODO: check TARGETID if DLIPDR is same for more than one DP */
+       uint32_t expected_dlpidr = DP_DLPIDR_PROTVSN |
+                       (dap->multidrop_targetsel & DP_TARGETSEL_INSTANCEID_MASK);
+       if (dlpidr != expected_dlpidr) {
+               LOG_INFO("Read incorrect DLPIDR 0x%08" PRIx32
+                                " (possibly CTRL/STAT value)",
+                                dlpidr);
+               return ERROR_FAIL;
+       }
+
+       LOG_DEBUG_IO("Selected DP_TARGETSEL 0x%08" PRIx32, dap->multidrop_targetsel);
+       swd_multidrop_selected_dap = dap;
+
+       if (dpidr_ptr)
+               *dpidr_ptr = dpidr;
+
+       if (dlpidr_ptr)
+               *dlpidr_ptr = dlpidr;
+
+       return retval;
 }
 
-/** Executes all queued DAP operations. */
-static int swd_run(struct adiv5_dap *dap)
+static int swd_multidrop_select(struct adiv5_dap *dap)
 {
-       /* for now the SWD interface hard-wires a zero-size queue.  */
+       if (!dap_is_multidrop(dap))
+               return ERROR_OK;
 
-       /* FIXME but we still need to check and scrub
-        * any hardware errors ...
-        */
-       return ERROR_OK;
+       if (swd_multidrop_selected_dap == dap)
+               return ERROR_OK;
+
+       int retval = ERROR_OK;
+       for (unsigned int retry = 0; ; retry++) {
+               bool clear_sticky = retry > 0;
+
+               retval = swd_multidrop_select_inner(dap, NULL, NULL, clear_sticky);
+               if (retval == ERROR_OK)
+                       break;
+
+               swd_multidrop_selected_dap = NULL;
+               if (retry > 3) {
+                       LOG_ERROR("Failed to select multidrop %s", adiv5_dap_name(dap));
+                       return retval;
+               }
+
+               LOG_DEBUG("Failed to select multidrop %s, retrying...",
+                                 adiv5_dap_name(dap));
+       }
+
+       return retval;
 }
 
-const struct dap_ops swd_dap_ops = {
-       .is_swd = true,
+static int swd_connect_multidrop(struct adiv5_dap *dap)
+{
+       int retval;
+       uint32_t dpidr = 0xdeadbeef;
+       uint32_t dlpidr = 0xdeadbeef;
+       int64_t timeout = timeval_ms() + 500;
 
-       .queue_idcode_read = swd_queue_idcode_read,
-       .queue_dp_read = swd_queue_dp_read,
-       .queue_dp_write = swd_queue_dp_write,
-       .queue_ap_read = swd_queue_ap_read,
-       .queue_ap_write = swd_queue_ap_write,
-       .queue_ap_abort = swd_queue_ap_abort,
-       .run = swd_run,
-};
+       do {
+               swd_send_sequence(dap, JTAG_TO_DORMANT);
+               swd_send_sequence(dap, DORMANT_TO_SWD);
 
-/*
- * This represents the bits which must be sent out on TMS/SWDIO to
- * switch a DAP implemented using an SWJ-DP module into SWD mode.
- * These bits are stored (and transmitted) LSB-first.
- *
- * See the DAP-Lite specification, section 2.2.5 for information
- * about making the debug link select SWD or JTAG.  (Similar info
- * is in a few other ARM documents.)
- */
-static const uint8_t jtag2swd_bitseq[] = {
-       /* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
-        * putting both JTAG and SWD logic into reset state.
+               /* Clear link state, including the SELECT cache. */
+               dap->do_reconnect = false;
+               dap_invalidate_cache(dap);
+               swd_multidrop_selected_dap = NULL;
+
+               retval = swd_multidrop_select_inner(dap, &dpidr, &dlpidr, true);
+               if (retval == ERROR_OK)
+                       break;
+
+               alive_sleep(1);
+
+       } while (timeval_ms() < timeout);
+
+       if (retval != ERROR_OK) {
+               swd_multidrop_selected_dap = NULL;
+               LOG_ERROR("Failed to connect multidrop %s", adiv5_dap_name(dap));
+               return retval;
+       }
+
+       LOG_INFO("SWD DPIDR 0x%08" PRIx32 ", DLPIDR 0x%08" PRIx32,
+                         dpidr, dlpidr);
+
+       return retval;
+}
+
+static int swd_connect_single(struct adiv5_dap *dap)
+{
+       int retval;
+       uint32_t dpidr = 0xdeadbeef;
+       int64_t timeout = timeval_ms() + 500;
+
+       do {
+               if (dap->switch_through_dormant) {
+                       swd_send_sequence(dap, JTAG_TO_DORMANT);
+                       swd_send_sequence(dap, DORMANT_TO_SWD);
+               } else {
+                       swd_send_sequence(dap, JTAG_TO_SWD);
+               }
+
+               /* Clear link state, including the SELECT cache. */
+               dap->do_reconnect = false;
+               dap_invalidate_cache(dap);
+
+               /* The sequences to enter in SWD (JTAG_TO_SWD and DORMANT_TO_SWD) end
+                * with a SWD line reset sequence (50 clk with SWDIO high).
+                * From ARM IHI 0074C ADIv6.0, chapter B4.3.3 "Connection and line reset
+                * sequence":
+                * - line reset sets DP_SELECT_DPBANK to zero;
+                * - read of DP_DPIDR takes the connection out of reset;
+                * - write of DP_TARGETSEL keeps the connection in reset;
+                * - other accesses return protocol error (SWDIO not driven by target).
+                *
+                * Read DP_DPIDR to get out of reset. Initialize dap->select to zero to
+                * skip the write to DP_SELECT, avoiding the protocol error. Set again
+                * dap->select to DP_SELECT_INVALID because the rest of the register is
+                * unknown after line reset.
+                */
+               dap->select = 0;
+               retval = swd_queue_dp_read_inner(dap, DP_DPIDR, &dpidr);
+               if (retval == ERROR_OK) {
+                       retval = swd_run_inner(dap);
+                       if (retval == ERROR_OK)
+                               break;
+               }
+
+               alive_sleep(1);
+
+               dap->switch_through_dormant = !dap->switch_through_dormant;
+       } while (timeval_ms() < timeout);
+
+       dap->select = DP_SELECT_INVALID;
+
+       if (retval != ERROR_OK) {
+               LOG_ERROR("Error connecting DP: cannot read IDR");
+               return retval;
+       }
+
+       LOG_INFO("SWD DPIDR 0x%08" PRIx32, dpidr);
+
+       do {
+               dap->do_reconnect = false;
+
+               /* force clear all sticky faults */
+               swd_clear_sticky_errors(dap);
+
+               retval = swd_run_inner(dap);
+               if (retval != ERROR_WAIT)
+                       break;
+
+               alive_sleep(10);
+
+       } while (timeval_ms() < timeout);
+
+       return retval;
+}
+
+static int swd_connect(struct adiv5_dap *dap)
+{
+       int status;
+
+       /* FIXME validate transport config ... is the
+        * configured DAP present (check IDCODE)?
         */
-       0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-       /* Switching sequence enables SWD and disables JTAG
-        * NOTE: bits in the DP's IDCODE may expose the need for
-        * an old/obsolete/deprecated sequence (0xb6 0xed).
+
+       /* 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");
+               }
+       }
+
+       if (dap_is_multidrop(dap))
+               status = swd_connect_multidrop(dap);
+       else
+               status = swd_connect_single(dap);
+
+       /* IHI 0031E B4.3.2:
+        * "A WAIT response must not be issued to the ...
+        * ... writes to the ABORT register"
+        * swd_clear_sticky_errors() writes to the ABORT register only.
+        *
+        * Unfortunately at least Microchip SAMD51/E53/E54 returns WAIT
+        * in a corner case. Just try if ABORT resolves the problem.
         */
-       0x9e, 0xe7,
-       /* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
-        * putting both JTAG and SWD logic into reset state.
+       if (status == ERROR_WAIT) {
+               LOG_WARNING("Connecting DP: stalled AP operation, issuing ABORT");
+
+               dap->do_reconnect = false;
+
+               status = swd_queue_dp_write_inner(dap, DP_ABORT,
+                       DAPABORT | STKCMPCLR | STKERRCLR | WDERRCLR | ORUNERRCLR);
+
+               if (status == ERROR_OK)
+                       status = swd_run_inner(dap);
+       }
+
+       if (status == ERROR_OK)
+               status = dap_dp_init(dap);
+
+       return status;
+}
+
+static int swd_check_reconnect(struct adiv5_dap *dap)
+{
+       if (dap->do_reconnect)
+               return swd_connect(dap);
+
+       return ERROR_OK;
+}
+
+static int swd_queue_ap_abort(struct adiv5_dap *dap, uint8_t *ack)
+{
+       const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
+       assert(swd);
+
+       /* TODO: Send DAPABORT in swd_multidrop_select_inner()
+        * in the case the multidrop dap is not selected?
+        * swd_queue_ap_abort() is not currently used anyway...
         */
-       0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
-};
+       int retval = swd_multidrop_select(dap);
+       if (retval != ERROR_OK)
+               return retval;
 
-/**
- * Put the debug link into SWD mode, if the target supports it.
- * The link's initial mode may be either JTAG (for example,
- * with SWJ-DP after reset) or SWD.
- *
- * @param target Enters SWD mode (if possible).
- *
- * Note that targets using the JTAG-DP do not support SWD, and that
- * some targets which could otherwise support it may have have been
- * configured to disable SWD signaling
- *
- * @return ERROR_OK or else a fault code.
- */
-int dap_to_swd(struct target *target)
+       swd->write_reg(swd_cmd(false, false, DP_ABORT),
+               DAPABORT | STKCMPCLR | STKERRCLR | WDERRCLR | ORUNERRCLR, 0);
+       return check_sync(dap);
+}
+
+static int swd_queue_dp_read(struct adiv5_dap *dap, unsigned reg,
+               uint32_t *data)
+{
+       int retval = swd_check_reconnect(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       retval = swd_multidrop_select(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       return swd_queue_dp_read_inner(dap, reg, data);
+}
+
+static int swd_queue_dp_write(struct adiv5_dap *dap, unsigned reg,
+               uint32_t data)
+{
+       const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
+       assert(swd);
+
+       int retval = swd_check_reconnect(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       retval = swd_multidrop_select(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       return swd_queue_dp_write_inner(dap, reg, data);
+}
+
+/** Select the AP register bank matching bits 7:4 of reg. */
+static int swd_queue_ap_bankselect(struct adiv5_ap *ap, unsigned reg)
 {
-       struct arm *arm = target_to_arm(target);
        int retval;
+       struct adiv5_dap *dap = ap->dap;
+       uint64_t sel;
 
-       LOG_DEBUG("Enter SWD mode");
+       if (is_adiv6(dap)) {
+               sel = ap->ap_num | (reg & 0x00000FF0);
+               if (sel == (dap->select & ~0xfULL))
+                       return ERROR_OK;
 
-       /* REVISIT it's ugly to need to make calls to a "jtag"
-        * subsystem if the link may not be in JTAG mode...
-        */
+               if (dap->select != DP_SELECT_INVALID)
+                       sel |= dap->select & 0xf;
+               dap->select = sel;
+               LOG_DEBUG("AP BANKSEL: %" PRIx64, sel);
+
+               retval = swd_queue_dp_write(dap, DP_SELECT, (uint32_t)sel);
+
+               if (retval == ERROR_OK && dap->asize > 32)
+                       retval = swd_queue_dp_write(dap, DP_SELECT1, (uint32_t)(sel >> 32));
 
-       retval =  jtag_add_tms_seq(8 * sizeof(jtag2swd_bitseq),
-                       jtag2swd_bitseq, TAP_INVALID);
-       if (retval == ERROR_OK)
-               retval = jtag_execute_queue();
+               if (retval != ERROR_OK)
+                       dap->select = DP_SELECT_INVALID;
 
-       /* set up the DAP's ops vector for SWD mode. */
-       arm->dap->ops = &swd_dap_ops;
+               return retval;
+       }
+
+       /* ADIv5 */
+       sel = (ap->ap_num << 24) | (reg & 0x000000F0);
+       if (dap->select != DP_SELECT_INVALID)
+               sel |= dap->select & DP_SELECT_DPBANK;
+
+       if (sel == dap->select)
+               return ERROR_OK;
+
+       dap->select = sel;
+
+       retval = swd_queue_dp_write_inner(dap, DP_SELECT, sel);
+       if (retval != ERROR_OK)
+               dap->select = DP_SELECT_INVALID;
 
        return retval;
 }
 
+static int swd_queue_ap_read(struct adiv5_ap *ap, unsigned reg,
+               uint32_t *data)
+{
+       struct adiv5_dap *dap = ap->dap;
+       const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
+       assert(swd);
+
+       int retval = swd_check_reconnect(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       retval = swd_multidrop_select(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       retval = swd_queue_ap_bankselect(ap, reg);
+       if (retval != ERROR_OK)
+               return retval;
 
+       swd->read_reg(swd_cmd(true, true, reg), dap->last_read, ap->memaccess_tck);
+       dap->last_read = data;
 
-COMMAND_HANDLER(handle_swd_wcr)
+       return check_sync(dap);
+}
+
+static int swd_queue_ap_write(struct adiv5_ap *ap, unsigned reg,
+               uint32_t data)
 {
-       int retval;
-       struct target *target = get_current_target(CMD_CTX);
-       struct arm *arm = target_to_arm(target);
-struct adiv5_dap *dap = arm->dap;
-       uint32_t wcr;
-       unsigned trn, scale = 0;
-
-
-       switch (CMD_ARGC) {
-       /* no-args: just dump state */
-       case 0:
-               //retval = swd_queue_dp_read(dap, DP_WCR, &wcr);
-               retval = dap_queue_dp_read(dap, DP_WCR, &wcr);
-               if (retval == ERROR_OK)
-                       dap->ops->run(dap);
-               if (retval != ERROR_OK) {
-                       LOG_ERROR("can't read WCR?");
-                       return retval;
-               }
+       struct adiv5_dap *dap = ap->dap;
+       const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
+       assert(swd);
 
-               command_print(CMD_CTX,
-                       "turnaround=%d, prescale=%d",
-                       WCR_TO_TRN(wcr),
-                       WCR_TO_PRESCALE(wcr));
-       return ERROR_OK;
+       int retval = swd_check_reconnect(dap);
+       if (retval != ERROR_OK)
+               return retval;
 
-       case 2:         /* TRN and prescale */
-               COMMAND_PARSE_NUMBER(uint, CMD_ARGV[1], scale);
-               if (scale > 7) {
-                       LOG_ERROR("prescale %d is too big", scale);
-                       return ERROR_FAIL;
-               }
-               /* FALL THROUGH */
+       retval = swd_multidrop_select(dap);
+       if (retval != ERROR_OK)
+               return retval;
 
-       case 1:         /* TRN only */
-               COMMAND_PARSE_NUMBER(uint, CMD_ARGV[0], trn);
-               if (trn < 1 || trn > 4) {
-                       LOG_ERROR("turnaround %d is invalid", trn);
-                       return ERROR_FAIL;
-               }
+       swd_finish_read(dap);
 
-               wcr = ((trn - 1) << 8) | scale;
-               /* FIXME
-                * write WCR ...
-                * then, re-init adapter with new TRN
-                */
-               LOG_ERROR("can't yet modify WCR");
-               return ERROR_FAIL;
+       retval = swd_queue_ap_bankselect(ap, reg);
+       if (retval != ERROR_OK)
+               return retval;
+
+       swd->write_reg(swd_cmd(false, true, reg), data, ap->memaccess_tck);
+
+       return check_sync(dap);
+}
+
+/** Executes all queued DAP operations. */
+static int swd_run(struct adiv5_dap *dap)
+{
+       int retval = swd_multidrop_select(dap);
+       if (retval != ERROR_OK)
+               return retval;
+
+       swd_finish_read(dap);
 
-       default:        /* too many arguments */
-               return ERROR_COMMAND_SYNTAX_ERROR;
+       return swd_run_inner(dap);
+}
+
+/** Put the SWJ-DP back to JTAG mode */
+static void swd_quit(struct adiv5_dap *dap)
+{
+       const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
+       static bool done;
+
+       /* There is no difference if the sequence is sent at the last
+        * or the first swd_quit() call, send it just once */
+       if (done)
+               return;
+
+       done = true;
+       if (dap_is_multidrop(dap)) {
+               swd->switch_seq(SWD_TO_DORMANT);
+               /* Revisit!
+                * Leaving DPs in dormant state was tested and offers some safety
+                * against DPs mismatch in case of unintentional use of non-multidrop SWD.
+                * To put SWJ-DPs to power-on state issue
+                * swd->switch_seq(DORMANT_TO_JTAG);
+                */
+       } else {
+               if (dap->switch_through_dormant) {
+                       swd->switch_seq(SWD_TO_DORMANT);
+                       swd->switch_seq(DORMANT_TO_JTAG);
+               } else {
+                       swd->switch_seq(SWD_TO_JTAG);
+               }
        }
+
+       /* flush the queue to shift out the sequence before exit */
+       swd->run();
 }
 
+const struct dap_ops swd_dap_ops = {
+       .connect = swd_connect,
+       .send_sequence = swd_send_sequence,
+       .queue_dp_read = swd_queue_dp_read,
+       .queue_dp_write = swd_queue_dp_write,
+       .queue_ap_read = swd_queue_ap_read,
+       .queue_ap_write = swd_queue_ap_write,
+       .queue_ap_abort = swd_queue_ap_abort,
+       .run = swd_run,
+       .quit = swd_quit,
+};
+
 static const struct command_registration swd_commands[] = {
        {
                /*
@@ -259,15 +659,6 @@ static const struct command_registration swd_commands[] = {
                .mode = COMMAND_CONFIG,
                .help = "declare a new SWD DAP"
        },
-       {
-               .name = "wcr",
-               .handler = handle_swd_wcr,
-               .mode = COMMAND_ANY,
-               .help = "display or update DAP's WCR register",
-               .usage = "turnaround (1..4), prescale (0..7)",
-       },
-
-       /* REVISIT -- add a command for SWV trace on/off */
        COMMAND_REGISTRATION_DONE
 };
 
@@ -277,17 +668,19 @@ static const struct command_registration swd_handlers[] = {
                .mode = COMMAND_ANY,
                .help = "SWD command group",
                .chain = swd_commands,
+               .usage = "",
        },
        COMMAND_REGISTRATION_DONE
 };
 
 static int swd_select(struct command_context *ctx)
 {
-       struct target *target = get_current_target(ctx);
+       /* FIXME: only place where global 'adapter_driver' is still needed */
+       extern struct adapter_driver *adapter_driver;
+       const struct swd_driver *swd = adapter_driver->swd_ops;
        int retval;
 
        retval = register_commands(ctx, NULL, swd_handlers);
-
        if (retval != ERROR_OK)
                return retval;
 
@@ -299,45 +692,20 @@ static int swd_select(struct command_context *ctx)
                return ERROR_FAIL;
        }
 
-        retval = swd->init(1);
+       retval = swd->init();
        if (retval != ERROR_OK) {
                LOG_DEBUG("can't init SWD driver");
                return retval;
        }
 
-       /* force DAP into SWD mode (not JTAG) */
-       retval = dap_to_swd(target);
-
        return retval;
 }
 
 static int swd_init(struct command_context *ctx)
 {
-       struct target *target = get_current_target(ctx);
-       struct arm *arm = target_to_arm(target);
-struct adiv5_dap *dap = arm->dap;
-       uint32_t idcode;
-       int status;
-
-
-       /* FIXME validate transport config ... is the
-        * configured DAP present (check IDCODE)?
-        * Is *only* one DAP configured?
-        *
-        * MUST READ IDCODE
-        */
-
- /* Note, debugport_init() does setup too */
-
-       uint8_t ack;
-
-       status = swd_queue_idcode_read(dap, &ack, &idcode);
-
-       if (status == ERROR_OK)
-               LOG_INFO("SWD IDCODE %#8.8x", idcode);
-
-       return status;
-
+       /* nothing done here, SWD is initialized
+        * together with the DAP */
+       return ERROR_OK;
 }
 
 static struct transport swd_transport = {