1 /***************************************************************************
2 * Copyright (C) 2009 Zachary T Welch *
3 * zw@superlucidity.net *
5 * Copyright (C) 2007,2008,2009 Øyvind Harboe *
6 * oyvind.harboe@zylin.com *
8 * Copyright (C) 2009 SoftPLC Corporation *
12 * Copyright (C) 2005 by Dominic Rath *
13 * Dominic.Rath@gmx.de *
15 * This program is free software; you can redistribute it and/or modify *
16 * it under the terms of the GNU General Public License as published by *
17 * the Free Software Foundation; either version 2 of the License, or *
18 * (at your option) any later version. *
20 * This program is distributed in the hope that it will be useful, *
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
23 * GNU General Public License for more details. *
25 * You should have received a copy of the GNU General Public License *
26 * along with this program; if not, write to the *
27 * Free Software Foundation, Inc., *
28 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
29 ***************************************************************************/
35 #include "interface.h"
36 #include "transport.h"
42 /* SVF and XSVF are higher level JTAG command sets (for boundary scan) */
44 #include "xsvf/xsvf.h"
46 /// The number of JTAG queue flushes (for profiling and debugging purposes).
47 static int jtag_flush_queue_count;
49 static void jtag_add_scan_check(struct jtag_tap *active,
50 void (*jtag_add_scan)(struct jtag_tap *active, int in_num_fields, const struct scan_field *in_fields, tap_state_t state),
51 int in_num_fields, struct scan_field *in_fields, tap_state_t state);
54 * The jtag_error variable is set when an error occurs while executing
55 * the queue. Application code may set this using jtag_set_error(),
56 * when an error occurs during processing that should be reported during
57 * jtag_execute_queue().
59 * The value is set and cleared, but never read by normal application code.
61 * This value is returned (and cleared) by jtag_execute_queue().
63 static int jtag_error = ERROR_OK;
65 static const char *jtag_event_strings[] =
67 [JTAG_TRST_ASSERTED] = "TAP reset",
68 [JTAG_TAP_EVENT_SETUP] = "TAP setup",
69 [JTAG_TAP_EVENT_ENABLE] = "TAP enabled",
70 [JTAG_TAP_EVENT_DISABLE] = "TAP disabled",
74 * JTAG adapters must initialize with TRST and SRST de-asserted
75 * (they're negative logic, so that means *high*). But some
76 * hardware doesn't necessarily work that way ... so set things
77 * up so that jtag_init() always forces that state.
79 static int jtag_trst = -1;
80 static int jtag_srst = -1;
83 * List all TAPs that have been created.
85 static struct jtag_tap *__jtag_all_taps = NULL;
87 * The number of TAPs in the __jtag_all_taps list, used to track the
88 * assigned chain position to new TAPs
90 static unsigned jtag_num_taps = 0;
92 static enum reset_types jtag_reset_config = RESET_NONE;
93 tap_state_t cmd_queue_cur_state = TAP_RESET;
95 static bool jtag_verify_capture_ir = true;
96 static int jtag_verify = 1;
98 /* how long the OpenOCD should wait before attempting JTAG communication after reset lines deasserted (in ms) */
99 static int adapter_nsrst_delay = 0; /* default to no nSRST delay */
100 static int jtag_ntrst_delay = 0; /* default to no nTRST delay */
101 static int adapter_nsrst_assert_width = 0; /* width of assertion */
102 static int jtag_ntrst_assert_width = 0; /* width of assertion */
105 * Contains a single callback along with a pointer that will be passed
106 * when an event occurs.
108 struct jtag_event_callback {
110 jtag_event_handler_t callback;
111 /// the private data to pass to the callback
113 /// the next callback
114 struct jtag_event_callback* next;
117 /* callbacks to inform high-level handlers about JTAG state changes */
118 static struct jtag_event_callback *jtag_event_callbacks;
121 static int speed_khz = 0;
122 /* speed to fallback to when RCLK is requested but not supported */
123 static int rclk_fallback_speed_khz = 0;
124 static enum {CLOCK_MODE_SPEED, CLOCK_MODE_KHZ, CLOCK_MODE_RCLK} clock_mode;
125 static int jtag_speed = 0;
127 static struct jtag_interface *jtag = NULL;
130 struct jtag_interface *jtag_interface = NULL;
132 void jtag_set_error(int error)
134 if ((error == ERROR_OK) || (jtag_error != ERROR_OK))
139 int jtag_error_clear(void)
141 int temp = jtag_error;
142 jtag_error = ERROR_OK;
148 static bool jtag_poll = 1;
150 bool is_jtag_poll_safe(void)
152 /* Polling can be disabled explicitly with set_enabled(false).
153 * It is also implicitly disabled while TRST is active and
154 * while SRST is gating the JTAG clock.
156 if (!jtag_poll || jtag_trst != 0)
158 return jtag_srst == 0 || (jtag_reset_config & RESET_SRST_NO_GATING);
161 bool jtag_poll_get_enabled(void)
166 void jtag_poll_set_enabled(bool value)
173 struct jtag_tap *jtag_all_taps(void)
175 return __jtag_all_taps;
178 unsigned jtag_tap_count(void)
180 return jtag_num_taps;
183 unsigned jtag_tap_count_enabled(void)
185 struct jtag_tap *t = jtag_all_taps();
196 /// Append a new TAP to the chain of all taps.
197 void jtag_tap_add(struct jtag_tap *t)
199 t->abs_chain_position = jtag_num_taps++;
201 struct jtag_tap **tap = &__jtag_all_taps;
203 tap = &(*tap)->next_tap;
207 /* returns a pointer to the n-th device in the scan chain */
208 static inline struct jtag_tap *jtag_tap_by_position(unsigned n)
210 struct jtag_tap *t = jtag_all_taps();
218 struct jtag_tap *jtag_tap_by_string(const char *s)
220 /* try by name first */
221 struct jtag_tap *t = jtag_all_taps();
225 if (0 == strcmp(t->dotted_name, s))
230 /* no tap found by name, so try to parse the name as a number */
232 if (parse_uint(s, &n) != ERROR_OK)
235 /* FIXME remove this numeric fallback code late June 2010, along
236 * with all info in the User's Guide that TAPs have numeric IDs.
237 * Also update "scan_chain" output to not display the numbers.
239 t = jtag_tap_by_position(n);
241 LOG_WARNING("Specify TAP '%s' by name, not number %u",
247 struct jtag_tap* jtag_tap_next_enabled(struct jtag_tap* p)
249 p = p ? p->next_tap : jtag_all_taps();
259 const char *jtag_tap_name(const struct jtag_tap *tap)
261 return (tap == NULL) ? "(unknown)" : tap->dotted_name;
265 int jtag_register_event_callback(jtag_event_handler_t callback, void *priv)
267 struct jtag_event_callback **callbacks_p = &jtag_event_callbacks;
269 if (callback == NULL)
271 return ERROR_INVALID_ARGUMENTS;
276 while ((*callbacks_p)->next)
277 callbacks_p = &((*callbacks_p)->next);
278 callbacks_p = &((*callbacks_p)->next);
281 (*callbacks_p) = malloc(sizeof(struct jtag_event_callback));
282 (*callbacks_p)->callback = callback;
283 (*callbacks_p)->priv = priv;
284 (*callbacks_p)->next = NULL;
289 int jtag_unregister_event_callback(jtag_event_handler_t callback, void *priv)
291 struct jtag_event_callback **callbacks_p;
292 struct jtag_event_callback **next;
294 if (callback == NULL)
296 return ERROR_INVALID_ARGUMENTS;
299 for (callbacks_p = &jtag_event_callbacks;
300 *callbacks_p != NULL;
303 next = &((*callbacks_p)->next);
305 if ((*callbacks_p)->priv != priv)
308 if ((*callbacks_p)->callback == callback)
311 *callbacks_p = *next;
318 int jtag_call_event_callbacks(enum jtag_event event)
320 struct jtag_event_callback *callback = jtag_event_callbacks;
322 LOG_DEBUG("jtag event: %s", jtag_event_strings[event]);
326 struct jtag_event_callback *next;
328 /* callback may remove itself */
329 next = callback->next;
330 callback->callback(event, callback->priv);
337 static void jtag_checks(void)
339 assert(jtag_trst == 0);
342 static void jtag_prelude(tap_state_t state)
346 assert(state != TAP_INVALID);
348 cmd_queue_cur_state = state;
351 void jtag_alloc_in_value32(struct scan_field *field)
353 interface_jtag_alloc_in_value32(field);
356 void jtag_add_ir_scan_noverify(struct jtag_tap *active, const struct scan_field *in_fields,
361 int retval = interface_jtag_add_ir_scan(active, in_fields, state);
362 jtag_set_error(retval);
365 static void jtag_add_ir_scan_noverify_callback(struct jtag_tap *active, int dummy, const struct scan_field *in_fields,
368 jtag_add_ir_scan_noverify(active, in_fields, state);
371 void jtag_add_ir_scan(struct jtag_tap *active, struct scan_field *in_fields, tap_state_t state)
373 assert(state != TAP_RESET);
375 if (jtag_verify && jtag_verify_capture_ir)
377 /* 8 x 32 bit id's is enough for all invocations */
379 /* if we are to run a verification of the ir scan, we need to get the input back.
380 * We may have to allocate space if the caller didn't ask for the input back.
382 in_fields->check_value = active->expected;
383 in_fields->check_mask = active->expected_mask;
384 jtag_add_scan_check(active, jtag_add_ir_scan_noverify_callback, 1, in_fields, state);
387 jtag_add_ir_scan_noverify(active, in_fields, state);
391 void jtag_add_plain_ir_scan(int num_bits, const uint8_t *out_bits, uint8_t *in_bits,
394 assert(out_bits != NULL);
395 assert(state != TAP_RESET);
399 int retval = interface_jtag_add_plain_ir_scan(
400 num_bits, out_bits, in_bits, state);
401 jtag_set_error(retval);
404 static int jtag_check_value_inner(uint8_t *captured, uint8_t *in_check_value,
405 uint8_t *in_check_mask, int num_bits);
407 static int jtag_check_value_mask_callback(jtag_callback_data_t data0, jtag_callback_data_t data1, jtag_callback_data_t data2, jtag_callback_data_t data3)
409 return jtag_check_value_inner((uint8_t *)data0, (uint8_t *)data1, (uint8_t *)data2, (int)data3);
412 static void jtag_add_scan_check(struct jtag_tap *active, void (*jtag_add_scan)(struct jtag_tap *active, int in_num_fields, const struct scan_field *in_fields, tap_state_t state),
413 int in_num_fields, struct scan_field *in_fields, tap_state_t state)
415 for (int i = 0; i < in_num_fields; i++)
417 struct scan_field *field = &in_fields[i];
418 field->allocated = 0;
420 if (field->check_value || field->in_value)
422 interface_jtag_add_scan_check_alloc(field);
426 jtag_add_scan(active, in_num_fields, in_fields, state);
428 for (int i = 0; i < in_num_fields; i++)
430 if ((in_fields[i].check_value != NULL) && (in_fields[i].in_value != NULL))
432 /* this is synchronous for a minidriver */
433 jtag_add_callback4(jtag_check_value_mask_callback, (jtag_callback_data_t)in_fields[i].in_value,
434 (jtag_callback_data_t)in_fields[i].check_value,
435 (jtag_callback_data_t)in_fields[i].check_mask,
436 (jtag_callback_data_t)in_fields[i].num_bits);
438 if (in_fields[i].allocated)
440 free(in_fields[i].in_value);
442 if (in_fields[i].modified)
444 in_fields[i].in_value = NULL;
449 void jtag_add_dr_scan_check(struct jtag_tap *active, int in_num_fields, struct scan_field *in_fields, tap_state_t state)
453 jtag_add_scan_check(active, jtag_add_dr_scan, in_num_fields, in_fields, state);
456 jtag_add_dr_scan(active, in_num_fields, in_fields, state);
461 void jtag_add_dr_scan(struct jtag_tap *active, int in_num_fields, const struct scan_field *in_fields,
464 assert(state != TAP_RESET);
469 retval = interface_jtag_add_dr_scan(active, in_num_fields, in_fields, state);
470 jtag_set_error(retval);
473 void jtag_add_plain_dr_scan(int num_bits, const uint8_t *out_bits, uint8_t *in_bits,
476 assert(out_bits != NULL);
477 assert(state != TAP_RESET);
482 retval = interface_jtag_add_plain_dr_scan(num_bits, out_bits, in_bits, state);
483 jtag_set_error(retval);
486 void jtag_add_tlr(void)
488 jtag_prelude(TAP_RESET);
489 jtag_set_error(interface_jtag_add_tlr());
491 /* NOTE: order here matches TRST path in jtag_add_reset() */
492 jtag_call_event_callbacks(JTAG_TRST_ASSERTED);
493 jtag_notify_event(JTAG_TRST_ASSERTED);
497 * If supported by the underlying adapter, this clocks a raw bit sequence
498 * onto TMS for switching betwen JTAG and SWD modes.
500 * DO NOT use this to bypass the integrity checks and logging provided
501 * by the jtag_add_pathmove() and jtag_add_statemove() calls.
503 * @param nbits How many bits to clock out.
504 * @param seq The bit sequence. The LSB is bit 0 of seq[0].
505 * @param state The JTAG tap state to record on completion. Use
506 * TAP_INVALID to represent being in in SWD mode.
508 * @todo Update naming conventions to stop assuming everything is JTAG.
510 int jtag_add_tms_seq(unsigned nbits, const uint8_t *seq, enum tap_state state)
514 if (!(jtag->supported & DEBUG_CAP_TMS_SEQ))
515 return ERROR_JTAG_NOT_IMPLEMENTED;
518 cmd_queue_cur_state = state;
520 retval = interface_add_tms_seq(nbits, seq, state);
521 jtag_set_error(retval);
525 void jtag_add_pathmove(int num_states, const tap_state_t *path)
527 tap_state_t cur_state = cmd_queue_cur_state;
529 /* the last state has to be a stable state */
530 if (!tap_is_state_stable(path[num_states - 1]))
532 LOG_ERROR("BUG: TAP path doesn't finish in a stable state");
533 jtag_set_error(ERROR_JTAG_NOT_STABLE_STATE);
537 for (int i = 0; i < num_states; i++)
539 if (path[i] == TAP_RESET)
541 LOG_ERROR("BUG: TAP_RESET is not a valid state for pathmove sequences");
542 jtag_set_error(ERROR_JTAG_STATE_INVALID);
546 if (tap_state_transition(cur_state, true) != path[i]
547 && tap_state_transition(cur_state, false) != path[i])
549 LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition",
550 tap_state_name(cur_state), tap_state_name(path[i]));
551 jtag_set_error(ERROR_JTAG_TRANSITION_INVALID);
559 jtag_set_error(interface_jtag_add_pathmove(num_states, path));
560 cmd_queue_cur_state = path[num_states - 1];
563 int jtag_add_statemove(tap_state_t goal_state)
565 tap_state_t cur_state = cmd_queue_cur_state;
567 if (goal_state != cur_state)
569 LOG_DEBUG("cur_state=%s goal_state=%s",
570 tap_state_name(cur_state),
571 tap_state_name(goal_state));
574 /* If goal is RESET, be paranoid and force that that transition
575 * (e.g. five TCK cycles, TMS high). Else trust "cur_state".
577 if (goal_state == TAP_RESET)
579 else if (goal_state == cur_state)
580 /* nothing to do */ ;
582 else if (tap_is_state_stable(cur_state) && tap_is_state_stable(goal_state))
584 unsigned tms_bits = tap_get_tms_path(cur_state, goal_state);
585 unsigned tms_count = tap_get_tms_path_len(cur_state, goal_state);
586 tap_state_t moves[8];
587 assert(tms_count < ARRAY_SIZE(moves));
589 for (unsigned i = 0; i < tms_count; i++, tms_bits >>= 1)
591 bool bit = tms_bits & 1;
593 cur_state = tap_state_transition(cur_state, bit);
594 moves[i] = cur_state;
597 jtag_add_pathmove(tms_count, moves);
599 else if (tap_state_transition(cur_state, true) == goal_state
600 || tap_state_transition(cur_state, false) == goal_state)
602 jtag_add_pathmove(1, &goal_state);
611 void jtag_add_runtest(int num_cycles, tap_state_t state)
614 jtag_set_error(interface_jtag_add_runtest(num_cycles, state));
618 void jtag_add_clocks(int num_cycles)
620 if (!tap_is_state_stable(cmd_queue_cur_state))
622 LOG_ERROR("jtag_add_clocks() called with TAP in unstable state \"%s\"",
623 tap_state_name(cmd_queue_cur_state));
624 jtag_set_error(ERROR_JTAG_NOT_STABLE_STATE);
631 jtag_set_error(interface_jtag_add_clocks(num_cycles));
635 void jtag_add_reset(int req_tlr_or_trst, int req_srst)
637 int trst_with_tlr = 0;
641 /* Without SRST, we must use target-specific JTAG operations
642 * on each target; callers should not be requesting SRST when
643 * that signal doesn't exist.
645 * RESET_SRST_PULLS_TRST is a board or chip level quirk, which
646 * can kick in even if the JTAG adapter can't drive TRST.
649 if (!(jtag_reset_config & RESET_HAS_SRST)) {
650 LOG_ERROR("BUG: can't assert SRST");
651 jtag_set_error(ERROR_FAIL);
654 if ((jtag_reset_config & RESET_SRST_PULLS_TRST) != 0
655 && !req_tlr_or_trst) {
656 LOG_ERROR("BUG: can't assert only SRST");
657 jtag_set_error(ERROR_FAIL);
663 /* JTAG reset (entry to TAP_RESET state) can always be achieved
664 * using TCK and TMS; that may go through a TAP_{IR,DR}UPDATE
665 * state first. TRST accelerates it, and bypasses those states.
667 * RESET_TRST_PULLS_SRST is a board or chip level quirk, which
668 * can kick in even if the JTAG adapter can't drive SRST.
670 if (req_tlr_or_trst) {
671 if (!(jtag_reset_config & RESET_HAS_TRST))
673 else if ((jtag_reset_config & RESET_TRST_PULLS_SRST) != 0
680 /* Maybe change TRST and/or SRST signal state */
681 if (jtag_srst != new_srst || jtag_trst != new_trst) {
684 retval = interface_jtag_add_reset(new_trst, new_srst);
685 if (retval != ERROR_OK)
686 jtag_set_error(retval);
688 retval = jtag_execute_queue();
690 if (retval != ERROR_OK) {
691 LOG_ERROR("TRST/SRST error %d", retval);
696 /* SRST resets everything hooked up to that signal */
697 if (jtag_srst != new_srst) {
698 jtag_srst = new_srst;
701 LOG_DEBUG("SRST line asserted");
702 if (adapter_nsrst_assert_width)
703 jtag_add_sleep(adapter_nsrst_assert_width * 1000);
706 LOG_DEBUG("SRST line released");
707 if (adapter_nsrst_delay)
708 jtag_add_sleep(adapter_nsrst_delay * 1000);
712 /* Maybe enter the JTAG TAP_RESET state ...
713 * - using only TMS, TCK, and the JTAG state machine
714 * - or else more directly, using TRST
716 * TAP_RESET should be invisible to non-debug parts of the system.
719 LOG_DEBUG("JTAG reset with TLR instead of TRST");
722 } else if (jtag_trst != new_trst) {
723 jtag_trst = new_trst;
725 LOG_DEBUG("TRST line asserted");
726 tap_set_state(TAP_RESET);
727 if (jtag_ntrst_assert_width)
728 jtag_add_sleep(jtag_ntrst_assert_width * 1000);
730 LOG_DEBUG("TRST line released");
731 if (jtag_ntrst_delay)
732 jtag_add_sleep(jtag_ntrst_delay * 1000);
734 /* We just asserted nTRST, so we're now in TAP_RESET.
735 * Inform possible listeners about this, now that
736 * JTAG instructions and data can be shifted. This
737 * sequence must match jtag_add_tlr().
739 jtag_call_event_callbacks(JTAG_TRST_ASSERTED);
740 jtag_notify_event(JTAG_TRST_ASSERTED);
745 void jtag_add_sleep(uint32_t us)
747 /// @todo Here, keep_alive() appears to be a layering violation!!!
749 jtag_set_error(interface_jtag_add_sleep(us));
752 static int jtag_check_value_inner(uint8_t *captured, uint8_t *in_check_value,
753 uint8_t *in_check_mask, int num_bits)
755 int retval = ERROR_OK;
759 compare_failed = buf_cmp_mask(captured, in_check_value, in_check_mask, num_bits);
761 compare_failed = buf_cmp(captured, in_check_value, num_bits);
763 if (compare_failed) {
764 char *captured_str, *in_check_value_str;
765 int bits = (num_bits > DEBUG_JTAG_IOZ)
769 /* NOTE: we've lost diagnostic context here -- 'which tap' */
771 captured_str = buf_to_str(captured, bits, 16);
772 in_check_value_str = buf_to_str(in_check_value, bits, 16);
774 LOG_WARNING("Bad value '%s' captured during DR or IR scan:",
776 LOG_WARNING(" check_value: 0x%s", in_check_value_str);
779 free(in_check_value_str);
782 char *in_check_mask_str;
784 in_check_mask_str = buf_to_str(in_check_mask, bits, 16);
785 LOG_WARNING(" check_mask: 0x%s", in_check_mask_str);
786 free(in_check_mask_str);
789 retval = ERROR_JTAG_QUEUE_FAILED;
794 void jtag_check_value_mask(struct scan_field *field, uint8_t *value, uint8_t *mask)
796 assert(field->in_value != NULL);
800 /* no checking to do */
804 jtag_execute_queue_noclear();
806 int retval = jtag_check_value_inner(field->in_value, value, mask, field->num_bits);
807 jtag_set_error(retval);
812 int default_interface_jtag_execute_queue(void)
816 LOG_ERROR("No JTAG interface configured yet. "
817 "Issue 'init' command in startup scripts "
818 "before communicating with targets.");
822 return jtag->execute_queue();
825 void jtag_execute_queue_noclear(void)
827 jtag_flush_queue_count++;
828 jtag_set_error(interface_jtag_execute_queue());
831 int jtag_get_flush_queue_count(void)
833 return jtag_flush_queue_count;
836 int jtag_execute_queue(void)
838 jtag_execute_queue_noclear();
839 return jtag_error_clear();
842 static int jtag_reset_callback(enum jtag_event event, void *priv)
844 struct jtag_tap *tap = priv;
846 if (event == JTAG_TRST_ASSERTED)
848 tap->enabled = !tap->disabled_after_reset;
850 /* current instruction is either BYPASS or IDCODE */
851 buf_set_ones(tap->cur_instr, tap->ir_length);
858 void jtag_sleep(uint32_t us)
860 alive_sleep(us/1000);
863 /* Maximum number of enabled JTAG devices we expect in the scan chain,
864 * plus one (to detect garbage at the end). Devices that don't support
865 * IDCODE take up fewer bits, possibly allowing a few more devices.
867 #define JTAG_MAX_CHAIN_SIZE 20
869 #define EXTRACT_MFG(X) (((X) & 0xffe) >> 1)
870 #define EXTRACT_PART(X) (((X) & 0xffff000) >> 12)
871 #define EXTRACT_VER(X) (((X) & 0xf0000000) >> 28)
873 /* A reserved manufacturer ID is used in END_OF_CHAIN_FLAG, so we
874 * know that no valid TAP will have it as an IDCODE value.
876 #define END_OF_CHAIN_FLAG 0x000000ff
878 /* a larger IR length than we ever expect to autoprobe */
879 #define JTAG_IRLEN_MAX 60
881 static int jtag_examine_chain_execute(uint8_t *idcode_buffer, unsigned num_idcode)
883 struct scan_field field = {
884 .num_bits = num_idcode * 32,
885 .out_value = idcode_buffer,
886 .in_value = idcode_buffer,
889 // initialize to the end of chain ID value
890 for (unsigned i = 0; i < JTAG_MAX_CHAIN_SIZE; i++)
891 buf_set_u32(idcode_buffer, i * 32, 32, END_OF_CHAIN_FLAG);
893 jtag_add_plain_dr_scan(field.num_bits, field.out_value, field.in_value, TAP_DRPAUSE);
895 return jtag_execute_queue();
898 static bool jtag_examine_chain_check(uint8_t *idcodes, unsigned count)
900 uint8_t zero_check = 0x0;
901 uint8_t one_check = 0xff;
903 for (unsigned i = 0; i < count * 4; i++)
905 zero_check |= idcodes[i];
906 one_check &= idcodes[i];
909 /* if there wasn't a single non-zero bit or if all bits were one,
910 * the scan is not valid. We wrote a mix of both values; either
912 * - There's a hardware issue (almost certainly):
913 * + all-zeroes can mean a target stuck in JTAG reset
914 * + all-ones tends to mean no target
915 * - The scan chain is WAY longer than we can handle, *AND* either
916 * + there are several hundreds of TAPs in bypass, or
917 * + at least a few dozen TAPs all have an all-ones IDCODE
919 if (zero_check == 0x00 || one_check == 0xff)
921 LOG_ERROR("JTAG scan chain interrogation failed: all %s",
922 (zero_check == 0x00) ? "zeroes" : "ones");
923 LOG_ERROR("Check JTAG interface, timings, target power, etc.");
929 static void jtag_examine_chain_display(enum log_levels level, const char *msg,
930 const char *name, uint32_t idcode)
932 log_printf_lf(level, __FILE__, __LINE__, __FUNCTION__,
933 "JTAG tap: %s %16.16s: 0x%08x "
934 "(mfg: 0x%3.3x, part: 0x%4.4x, ver: 0x%1.1x)",
936 (unsigned int)idcode,
937 (unsigned int)EXTRACT_MFG(idcode),
938 (unsigned int)EXTRACT_PART(idcode),
939 (unsigned int)EXTRACT_VER(idcode));
942 static bool jtag_idcode_is_final(uint32_t idcode)
945 * Some devices, such as AVR8, will output all 1's instead
946 * of TDI input value at end of chain. Allow those values
947 * instead of failing.
949 return idcode == END_OF_CHAIN_FLAG || idcode == 0xFFFFFFFF;
953 * This helper checks that remaining bits in the examined chain data are
954 * all as expected, but a single JTAG device requires only 64 bits to be
955 * read back correctly. This can help identify and diagnose problems
956 * with the JTAG chain earlier, gives more helpful/explicit error messages.
957 * Returns TRUE iff garbage was found.
959 static bool jtag_examine_chain_end(uint8_t *idcodes, unsigned count, unsigned max)
961 bool triggered = false;
962 for (; count < max - 31; count += 32)
964 uint32_t idcode = buf_get_u32(idcodes, count, 32);
966 /* do not trigger the warning if the data looks good */
967 if (jtag_idcode_is_final(idcode))
969 LOG_WARNING("Unexpected idcode after end of chain: %d 0x%08x",
970 count, (unsigned int)idcode);
976 static bool jtag_examine_chain_match_tap(const struct jtag_tap *tap)
978 uint32_t idcode = tap->idcode;
980 /* ignore expected BYPASS codes; warn otherwise */
981 if (0 == tap->expected_ids_cnt && !idcode)
984 /* optionally ignore the JTAG version field */
985 uint32_t mask = tap->ignore_version ? ~(0xff << 24) : ~0;
989 /* Loop over the expected identification codes and test for a match */
990 unsigned ii, limit = tap->expected_ids_cnt;
992 for (ii = 0; ii < limit; ii++)
994 uint32_t expected = tap->expected_ids[ii] & mask;
996 if (idcode == expected)
999 /* treat "-expected-id 0" as a "don't-warn" wildcard */
1000 if (0 == tap->expected_ids[ii])
1004 /* If none of the expected ids matched, warn */
1005 jtag_examine_chain_display(LOG_LVL_WARNING, "UNEXPECTED",
1006 tap->dotted_name, tap->idcode);
1007 for (ii = 0; ii < limit; ii++)
1011 snprintf(msg, sizeof(msg), "expected %u of %u", ii + 1, limit);
1012 jtag_examine_chain_display(LOG_LVL_ERROR, msg,
1013 tap->dotted_name, tap->expected_ids[ii]);
1018 /* Try to examine chain layout according to IEEE 1149.1 §12
1019 * This is called a "blind interrogation" of the scan chain.
1021 static int jtag_examine_chain(void)
1023 uint8_t idcode_buffer[JTAG_MAX_CHAIN_SIZE * 4];
1027 bool autoprobe = false;
1029 /* DR scan to collect BYPASS or IDCODE register contents.
1030 * Then make sure the scan data has both ones and zeroes.
1032 LOG_DEBUG("DR scan interrogation for IDCODE/BYPASS");
1033 retval = jtag_examine_chain_execute(idcode_buffer, JTAG_MAX_CHAIN_SIZE);
1034 if (retval != ERROR_OK)
1036 if (!jtag_examine_chain_check(idcode_buffer, JTAG_MAX_CHAIN_SIZE))
1037 return ERROR_JTAG_INIT_FAILED;
1039 /* point at the 1st tap */
1040 struct jtag_tap *tap = jtag_tap_next_enabled(NULL);
1046 tap && bit_count < (JTAG_MAX_CHAIN_SIZE * 32) - 31;
1047 tap = jtag_tap_next_enabled(tap))
1049 uint32_t idcode = buf_get_u32(idcode_buffer, bit_count, 32);
1051 if ((idcode & 1) == 0)
1053 /* Zero for LSB indicates a device in bypass */
1054 LOG_INFO("TAP %s does not have IDCODE",
1057 tap->hasidcode = false;
1063 /* Friendly devices support IDCODE */
1064 tap->hasidcode = true;
1065 jtag_examine_chain_display(LOG_LVL_INFO,
1067 tap->dotted_name, idcode);
1071 tap->idcode = idcode;
1073 /* ensure the TAP ID matches what was expected */
1074 if (!jtag_examine_chain_match_tap(tap))
1075 retval = ERROR_JTAG_INIT_SOFT_FAIL;
1078 /* Fail if too many TAPs were enabled for us to verify them all. */
1080 LOG_ERROR("Too many TAPs enabled; '%s' ignored.",
1082 return ERROR_JTAG_INIT_FAILED;
1085 /* if autoprobing, the tap list is still empty ... populate it! */
1086 while (autoprobe && bit_count < (JTAG_MAX_CHAIN_SIZE * 32) - 31) {
1090 /* Is there another TAP? */
1091 idcode = buf_get_u32(idcode_buffer, bit_count, 32);
1092 if (jtag_idcode_is_final(idcode))
1095 /* Default everything in this TAP except IR length.
1097 * REVISIT create a jtag_alloc(chip, tap) routine, and
1098 * share it with jim_newtap_cmd().
1100 tap = calloc(1, sizeof *tap);
1104 sprintf(buf, "auto%d", tapcount++);
1105 tap->chip = strdup(buf);
1106 tap->tapname = strdup("tap");
1108 sprintf(buf, "%s.%s", tap->chip, tap->tapname);
1109 tap->dotted_name = strdup(buf);
1111 /* tap->ir_length == 0 ... signifying irlen autoprobe */
1112 tap->ir_capture_mask = 0x03;
1113 tap->ir_capture_value = 0x01;
1115 tap->enabled = true;
1117 if ((idcode & 1) == 0) {
1119 tap->hasidcode = false;
1122 tap->hasidcode = true;
1123 tap->idcode = idcode;
1125 tap->expected_ids_cnt = 1;
1126 tap->expected_ids = malloc(sizeof(uint32_t));
1127 tap->expected_ids[0] = idcode;
1130 LOG_WARNING("AUTO %s - use \"jtag newtap "
1131 "%s %s -expected-id 0x%8.8" PRIx32 " ...\"",
1132 tap->dotted_name, tap->chip, tap->tapname,
1138 /* After those IDCODE or BYPASS register values should be
1139 * only the data we fed into the scan chain.
1141 if (jtag_examine_chain_end(idcode_buffer, bit_count,
1142 8 * sizeof(idcode_buffer))) {
1143 LOG_ERROR("double-check your JTAG setup (interface, "
1144 "speed, missing TAPs, ...)");
1145 return ERROR_JTAG_INIT_FAILED;
1148 /* Return success or, for backwards compatibility if only
1149 * some IDCODE values mismatched, a soft/continuable fault.
1155 * Validate the date loaded by entry to the Capture-IR state, to help
1156 * find errors related to scan chain configuration (wrong IR lengths)
1159 * Entry state can be anything. On non-error exit, all TAPs are in
1160 * bypass mode. On error exits, the scan chain is reset.
1162 static int jtag_validate_ircapture(void)
1164 struct jtag_tap *tap;
1165 int total_ir_length = 0;
1166 uint8_t *ir_test = NULL;
1167 struct scan_field field;
1172 /* when autoprobing, accomodate huge IR lengths */
1173 for (tap = NULL, total_ir_length = 0;
1174 (tap = jtag_tap_next_enabled(tap)) != NULL;
1175 total_ir_length += tap->ir_length) {
1176 if (tap->ir_length == 0)
1177 total_ir_length += JTAG_IRLEN_MAX;
1180 /* increase length to add 2 bit sentinel after scan */
1181 total_ir_length += 2;
1183 ir_test = malloc(DIV_ROUND_UP(total_ir_length, 8));
1184 if (ir_test == NULL)
1187 /* after this scan, all TAPs will capture BYPASS instructions */
1188 buf_set_ones(ir_test, total_ir_length);
1190 field.num_bits = total_ir_length;
1191 field.out_value = ir_test;
1192 field.in_value = ir_test;
1194 jtag_add_plain_ir_scan(field.num_bits, field.out_value, field.in_value, TAP_IDLE);
1196 LOG_DEBUG("IR capture validation scan");
1197 retval = jtag_execute_queue();
1198 if (retval != ERROR_OK)
1205 tap = jtag_tap_next_enabled(tap);
1210 /* If we're autoprobing, guess IR lengths. They must be at
1211 * least two bits. Guessing will fail if (a) any TAP does
1212 * not conform to the JTAG spec; or (b) when the upper bits
1213 * captured from some conforming TAP are nonzero. Or if
1214 * (c) an IR length is longer than 32 bits -- which is only
1215 * an implementation limit, which could someday be raised.
1217 * REVISIT optimization: if there's a *single* TAP we can
1218 * lift restrictions (a) and (b) by scanning a recognizable
1219 * pattern before the all-ones BYPASS. Check for where the
1220 * pattern starts in the result, instead of an 0...01 value.
1222 * REVISIT alternative approach: escape to some tcl code
1223 * which could provide more knowledge, based on IDCODE; and
1224 * only guess when that has no success.
1226 if (tap->ir_length == 0) {
1228 while ((val = buf_get_u32(ir_test, chain_pos,
1229 tap->ir_length + 1)) == 1
1230 && tap->ir_length <= 32) {
1233 LOG_WARNING("AUTO %s - use \"... -irlen %d\"",
1234 jtag_tap_name(tap), tap->ir_length);
1237 /* Validate the two LSBs, which must be 01 per JTAG spec.
1239 * Or ... more bits could be provided by TAP declaration.
1240 * Plus, some taps (notably in i.MX series chips) violate
1241 * this part of the JTAG spec, so their capture mask/value
1242 * attributes might disable this test.
1244 val = buf_get_u32(ir_test, chain_pos, tap->ir_length);
1245 if ((val & tap->ir_capture_mask) != tap->ir_capture_value) {
1246 LOG_ERROR("%s: IR capture error; saw 0x%0*x not 0x%0*x",
1248 (tap->ir_length + 7) / tap->ir_length,
1250 (tap->ir_length + 7) / tap->ir_length,
1251 (unsigned) tap->ir_capture_value);
1253 retval = ERROR_JTAG_INIT_FAILED;
1256 LOG_DEBUG("%s: IR capture 0x%0*x", jtag_tap_name(tap),
1257 (tap->ir_length + 7) / tap->ir_length, val);
1258 chain_pos += tap->ir_length;
1261 /* verify the '11' sentinel we wrote is returned at the end */
1262 val = buf_get_u32(ir_test, chain_pos, 2);
1265 char *cbuf = buf_to_str(ir_test, total_ir_length, 16);
1267 LOG_ERROR("IR capture error at bit %d, saw 0x%s not 0x...3",
1270 retval = ERROR_JTAG_INIT_FAILED;
1275 if (retval != ERROR_OK) {
1277 jtag_execute_queue();
1283 void jtag_tap_init(struct jtag_tap *tap)
1285 unsigned ir_len_bits;
1286 unsigned ir_len_bytes;
1288 /* if we're autoprobing, cope with potentially huge ir_length */
1289 ir_len_bits = tap->ir_length ? : JTAG_IRLEN_MAX;
1290 ir_len_bytes = DIV_ROUND_UP(ir_len_bits, 8);
1292 tap->expected = calloc(1, ir_len_bytes);
1293 tap->expected_mask = calloc(1, ir_len_bytes);
1294 tap->cur_instr = malloc(ir_len_bytes);
1296 /// @todo cope better with ir_length bigger than 32 bits
1297 if (ir_len_bits > 32)
1300 buf_set_u32(tap->expected, 0, ir_len_bits, tap->ir_capture_value);
1301 buf_set_u32(tap->expected_mask, 0, ir_len_bits, tap->ir_capture_mask);
1303 // TAP will be in bypass mode after jtag_validate_ircapture()
1305 buf_set_ones(tap->cur_instr, tap->ir_length);
1307 // register the reset callback for the TAP
1308 jtag_register_event_callback(&jtag_reset_callback, tap);
1310 LOG_DEBUG("Created Tap: %s @ abs position %d, "
1311 "irlen %d, capture: 0x%x mask: 0x%x", tap->dotted_name,
1312 tap->abs_chain_position, tap->ir_length,
1313 (unsigned) tap->ir_capture_value,
1314 (unsigned) tap->ir_capture_mask);
1318 void jtag_tap_free(struct jtag_tap *tap)
1320 jtag_unregister_event_callback(&jtag_reset_callback, tap);
1322 /// @todo is anything missing? no memory leaks please
1323 free((void *)tap->expected);
1324 free((void *)tap->expected_ids);
1325 free((void *)tap->chip);
1326 free((void *)tap->tapname);
1327 free((void *)tap->dotted_name);
1332 * Do low-level setup like initializing registers, output signals,
1335 int adapter_init(struct command_context *cmd_ctx)
1340 if (!jtag_interface)
1342 /* nothing was previously specified by "interface" command */
1343 LOG_ERROR("Debug Adapter has to be specified, "
1344 "see \"interface\" command");
1345 return ERROR_JTAG_INVALID_INTERFACE;
1348 jtag = jtag_interface;
1349 if (jtag_interface->init() != ERROR_OK)
1352 return ERROR_JTAG_INIT_FAILED;
1355 /* LEGACY SUPPORT ... adapter drivers must declare what
1356 * transports they allow. Until they all do so, assume
1357 * the legacy drivers are JTAG-only
1359 if (!transports_are_declared()) {
1360 static const char *jtag_only[] = { "jtag", NULL, };
1361 LOG_ERROR("Adapter driver '%s' did not declare "
1362 "which transports it allows; assuming"
1363 "JTAG-only", jtag->name);
1364 int retval = allow_transports(cmd_ctx, jtag_only);
1365 if (retval != ERROR_OK)
1370 int requested_khz = jtag_get_speed_khz();
1371 int actual_khz = requested_khz;
1372 int retval = jtag_get_speed_readable(&actual_khz);
1373 if (ERROR_OK != retval)
1374 LOG_INFO("adapter-specific clock speed value %d", jtag_get_speed());
1375 else if (actual_khz)
1377 /* Adaptive clocking -- JTAG-specific */
1378 if ((CLOCK_MODE_RCLK == clock_mode)
1379 || ((CLOCK_MODE_KHZ == clock_mode) && !requested_khz))
1381 LOG_INFO("RCLK (adaptive clock speed) not supported - fallback to %d kHz"
1385 LOG_INFO("clock speed %d kHz", actual_khz);
1388 LOG_INFO("RCLK (adaptive clock speed)");
1393 int jtag_init_inner(struct command_context *cmd_ctx)
1395 struct jtag_tap *tap;
1397 bool issue_setup = true;
1399 LOG_DEBUG("Init JTAG chain");
1401 tap = jtag_tap_next_enabled(NULL);
1403 /* Once JTAG itself is properly set up, and the scan chain
1404 * isn't absurdly large, IDCODE autoprobe should work fine.
1406 * But ... IRLEN autoprobe can fail even on systems which
1407 * are fully conformant to JTAG. Also, JTAG setup can be
1408 * quite finicky on some systems.
1410 * REVISIT: if TAP autoprobe works OK, then in many cases
1411 * we could escape to tcl code and set up targets based on
1412 * the TAP's IDCODE values.
1414 LOG_WARNING("There are no enabled taps. "
1415 "AUTO PROBING MIGHT NOT WORK!!");
1417 /* REVISIT default clock will often be too fast ... */
1421 if ((retval = jtag_execute_queue()) != ERROR_OK)
1424 /* Examine DR values first. This discovers problems which will
1425 * prevent communication ... hardware issues like TDO stuck, or
1426 * configuring the wrong number of (enabled) TAPs.
1428 retval = jtag_examine_chain();
1431 /* complete success */
1433 case ERROR_JTAG_INIT_SOFT_FAIL:
1434 /* For backward compatibility reasons, try coping with
1435 * configuration errors involving only ID mismatches.
1436 * We might be able to talk to the devices.
1438 LOG_ERROR("Trying to use configured scan chain anyway...");
1439 issue_setup = false;
1442 /* some hard error; already issued diagnostics */
1446 /* Now look at IR values. Problems here will prevent real
1447 * communication. They mostly mean that the IR length is
1448 * wrong ... or that the IR capture value is wrong. (The
1449 * latter is uncommon, but easily worked around: provide
1450 * ircapture/irmask values during TAP setup.)
1452 retval = jtag_validate_ircapture();
1453 if (retval != ERROR_OK)
1457 jtag_notify_event(JTAG_TAP_EVENT_SETUP);
1459 LOG_WARNING("Bypassing JTAG setup events due to errors");
1465 int adapter_quit(void)
1467 if (!jtag || !jtag->quit)
1470 // close the JTAG interface
1471 int result = jtag->quit();
1472 if (ERROR_OK != result)
1473 LOG_ERROR("failed: %d", result);
1479 int jtag_init_reset(struct command_context *cmd_ctx)
1483 if ((retval = adapter_init(cmd_ctx)) != ERROR_OK)
1486 LOG_DEBUG("Initializing with hard TRST+SRST reset");
1489 * This procedure is used by default when OpenOCD triggers a reset.
1490 * It's now done through an overridable Tcl "init_reset" wrapper.
1492 * This started out as a more powerful "get JTAG working" reset than
1493 * jtag_init_inner(), applying TRST because some chips won't activate
1494 * JTAG without a TRST cycle (presumed to be async, though some of
1495 * those chips synchronize JTAG activation using TCK).
1497 * But some chips only activate JTAG as part of an SRST cycle; SRST
1498 * got mixed in. So it became a hard reset routine, which got used
1499 * in more places, and which coped with JTAG reset being forced as
1500 * part of SRST (srst_pulls_trst).
1502 * And even more corner cases started to surface: TRST and/or SRST
1503 * assertion timings matter; some chips need other JTAG operations;
1504 * TRST/SRST sequences can need to be different from these, etc.
1506 * Systems should override that wrapper to support system-specific
1507 * requirements that this not-fully-generic code doesn't handle.
1509 * REVISIT once Tcl code can read the reset_config modes, this won't
1510 * need to be a C routine at all...
1512 jtag_add_reset(1, 0); /* TAP_RESET, using TMS+TCK or TRST */
1513 if (jtag_reset_config & RESET_HAS_SRST)
1515 jtag_add_reset(1, 1);
1516 if ((jtag_reset_config & RESET_SRST_PULLS_TRST) == 0)
1517 jtag_add_reset(0, 1);
1519 jtag_add_reset(0, 0);
1520 if ((retval = jtag_execute_queue()) != ERROR_OK)
1523 /* Check that we can communication on the JTAG chain + eventually we want to
1524 * be able to perform enumeration only after OpenOCD has started
1525 * telnet and GDB server
1527 * That would allow users to more easily perform any magic they need to before
1530 return jtag_init_inner(cmd_ctx);
1533 int jtag_init(struct command_context *cmd_ctx)
1537 if ((retval = adapter_init(cmd_ctx)) != ERROR_OK)
1540 /* guard against oddball hardware: force resets to be inactive */
1541 jtag_add_reset(0, 0);
1542 if ((retval = jtag_execute_queue()) != ERROR_OK)
1545 if (Jim_Eval_Named(cmd_ctx->interp, "jtag_init", __FILE__, __LINE__) != JIM_OK)
1551 unsigned jtag_get_speed_khz(void)
1556 static int adapter_khz_to_speed(unsigned khz, int* speed)
1558 LOG_DEBUG("convert khz to interface specific speed value");
1562 LOG_DEBUG("have interface set up");
1564 int retval = jtag->khz(jtag_get_speed_khz(), &speed_div1);
1565 if (ERROR_OK != retval)
1569 *speed = speed_div1;
1574 static int jtag_rclk_to_speed(unsigned fallback_speed_khz, int* speed)
1576 int retval = adapter_khz_to_speed(0, speed);
1577 if ((ERROR_OK != retval) && fallback_speed_khz)
1579 LOG_DEBUG("trying fallback speed...");
1580 retval = adapter_khz_to_speed(fallback_speed_khz, speed);
1585 static int jtag_set_speed(int speed)
1588 /* this command can be called during CONFIG,
1589 * in which case jtag isn't initialized */
1590 return jtag ? jtag->speed(speed) : ERROR_OK;
1593 int jtag_config_khz(unsigned khz)
1595 LOG_DEBUG("handle jtag khz");
1596 clock_mode = CLOCK_MODE_KHZ;
1598 int retval = adapter_khz_to_speed(khz, &speed);
1599 return (ERROR_OK != retval) ? retval : jtag_set_speed(speed);
1602 int jtag_config_rclk(unsigned fallback_speed_khz)
1604 LOG_DEBUG("handle jtag rclk");
1605 clock_mode = CLOCK_MODE_RCLK;
1606 rclk_fallback_speed_khz = fallback_speed_khz;
1608 int retval = jtag_rclk_to_speed(fallback_speed_khz, &speed);
1609 return (ERROR_OK != retval) ? retval : jtag_set_speed(speed);
1612 int jtag_get_speed(void)
1617 case CLOCK_MODE_SPEED:
1620 case CLOCK_MODE_KHZ:
1621 adapter_khz_to_speed(jtag_get_speed_khz(), &speed);
1623 case CLOCK_MODE_RCLK:
1624 jtag_rclk_to_speed(rclk_fallback_speed_khz, &speed);
1627 LOG_ERROR("BUG: unknown jtag clock mode");
1634 int jtag_get_speed_readable(int *khz)
1636 return jtag ? jtag->speed_div(jtag_get_speed(), khz) : ERROR_OK;
1639 void jtag_set_verify(bool enable)
1641 jtag_verify = enable;
1644 bool jtag_will_verify()
1649 void jtag_set_verify_capture_ir(bool enable)
1651 jtag_verify_capture_ir = enable;
1654 bool jtag_will_verify_capture_ir()
1656 return jtag_verify_capture_ir;
1659 int jtag_power_dropout(int *dropout)
1663 /* TODO: as the jtag interface is not valid all
1664 * we can do at the moment is exit OpenOCD */
1665 LOG_ERROR("No Valid JTAG Interface Configured.");
1668 return jtag->power_dropout(dropout);
1671 int jtag_srst_asserted(int *srst_asserted)
1673 return jtag->srst_asserted(srst_asserted);
1676 enum reset_types jtag_get_reset_config(void)
1678 return jtag_reset_config;
1680 void jtag_set_reset_config(enum reset_types type)
1682 jtag_reset_config = type;
1685 int jtag_get_trst(void)
1689 int jtag_get_srst(void)
1694 void jtag_set_nsrst_delay(unsigned delay)
1696 adapter_nsrst_delay = delay;
1698 unsigned jtag_get_nsrst_delay(void)
1700 return adapter_nsrst_delay;
1702 void jtag_set_ntrst_delay(unsigned delay)
1704 jtag_ntrst_delay = delay;
1706 unsigned jtag_get_ntrst_delay(void)
1708 return jtag_ntrst_delay;
1712 void jtag_set_nsrst_assert_width(unsigned delay)
1714 adapter_nsrst_assert_width = delay;
1716 unsigned jtag_get_nsrst_assert_width(void)
1718 return adapter_nsrst_assert_width;
1720 void jtag_set_ntrst_assert_width(unsigned delay)
1722 jtag_ntrst_assert_width = delay;
1724 unsigned jtag_get_ntrst_assert_width(void)
1726 return jtag_ntrst_assert_width;
1729 static int jtag_select(struct command_context *ctx)
1733 /* NOTE: interface init must already have been done.
1734 * That works with only C code ... no Tcl glue required.
1738 retval = jtag_register_commands(ctx);
1740 if (retval != ERROR_OK)
1743 retval = svf_register_commands(ctx);
1745 if (retval != ERROR_OK)
1748 return xsvf_register_commands(ctx);
1751 static struct transport jtag_transport = {
1753 .select = jtag_select,
1757 static void jtag_constructor(void) __attribute__((constructor));
1758 static void jtag_constructor(void)
1760 transport_register(&jtag_transport);
1763 /** Returns true if the current debug session
1764 * is using JTAG as its transport.
1766 bool transport_is_jtag(void)
1768 return get_current_transport() == &jtag_transport;