1 /***************************************************************************
2 * Copyright (C) 2005 by Dominic Rath *
3 * Dominic.Rath@gmx.de *
5 * Copyright (C) 2007,2008 Øyvind Harboe *
6 * oyvind.harboe@zylin.com *
8 * This program is free software; you can redistribute it and/or modify *
9 * it under the terms of the GNU General Public License as published by *
10 * the Free Software Foundation; either version 2 of the License, or *
11 * (at your option) any later version. *
13 * This program is distributed in the hope that it will be useful, *
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16 * GNU General Public License for more details. *
18 * You should have received a copy of the GNU General Public License *
19 * along with this program; if not, write to the *
20 * Free Software Foundation, Inc., *
21 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
22 ***************************************************************************/
26 #include "binarybuffer.h"
30 #ifdef _DEBUG_JTAG_IO_
31 #define DEBUG_JTAG_IO(expr ...) \
32 do { if (1) LOG_DEBUG(expr); } while (0)
34 #define DEBUG_JTAG_IO(expr ...) \
35 do { if (0) LOG_DEBUG(expr); } while (0)
38 #ifndef DEBUG_JTAG_IOZ
39 #define DEBUG_JTAG_IOZ 64
42 /*-----<Macros>--------------------------------------------------*/
45 * When given an array, compute its DIMension; in other words, the
46 * number of elements in the array
48 #define DIM(x) (sizeof(x)/sizeof((x)[0]))
50 /** Calculate the number of bytes required to hold @a n TAP scan bits */
51 #define TAP_SCAN_BYTES(n) CEIL(n, 8)
53 /*-----</Macros>-------------------------------------------------*/
56 * Defines JTAG Test Access Port states.
58 * These definitions were gleaned from the ARM7TDMI-S Technical
59 * Reference Manual and validated against several other ARM core
60 * technical manuals. tap_get_tms_path() is sensitive to this numbering
61 * and ordering of the TAP states; furthermore, some interfaces require
62 * specific numbers be used, as they are handed-off directly to their
63 * hardware implementations.
65 typedef enum tap_state
68 /* These are the old numbers. Leave as-is for now... */
69 TAP_RESET
= 0, TAP_IDLE
= 8,
70 TAP_DRSELECT
= 1, TAP_DRCAPTURE
= 2, TAP_DRSHIFT
= 3, TAP_DREXIT1
= 4,
71 TAP_DRPAUSE
= 5, TAP_DREXIT2
= 6, TAP_DRUPDATE
= 7,
72 TAP_IRSELECT
= 9, TAP_IRCAPTURE
= 10, TAP_IRSHIFT
= 11, TAP_IREXIT1
= 12,
73 TAP_IRPAUSE
= 13, TAP_IREXIT2
= 14, TAP_IRUPDATE
= 15,
75 TAP_NUM_STATES
= 16, TAP_INVALID
= -1,
77 /* Proper ARM recommended numbers */
95 TAP_NUM_STATES
= 0x10,
102 * Function tap_state_name
103 * Returns a string suitable for display representing the JTAG tap_state
105 const char *tap_state_name(tap_state_t state
);
107 /// Provides user-friendly name lookup of TAP states.
108 tap_state_t
tap_state_by_name(const char *name
);
110 /// The current TAP state of the pending JTAG command queue.
111 extern tap_state_t cmd_queue_cur_state
;
114 * This structure defines a single scan field in the scan. It provides
115 * fields for the field's width and pointers to scan input and output
118 * In addition, this structure includes a value and mask that is used by
119 * jtag_add_dr_scan_check() to validate the value that was scanned out.
121 * The allocated, modified, and intmp fields are internal work space.
123 typedef struct scan_field_s
125 /// A pointer to the tap structure to which this field refers.
128 /// The number of bits this field specifies (up to 32)
130 /// A pointer to value to be scanned into the device
132 /// A pointer to a 32-bit memory location for data scanned out
135 /// The value used to check the data scanned out.
136 uint8_t* check_value
;
137 /// The mask to go with check_value
140 /// in_value has been allocated for the queue
142 /// Indicates we modified the in_value.
144 /// temporary storage for performing value checks synchronously
148 typedef struct jtag_tap_event_action_s jtag_tap_event_action_t
;
150 /* this is really: typedef jtag_tap_t */
151 /* But - the typedef is done in "types.h" */
152 /* due to "forward declaration reasons" */
157 const char* dotted_name
;
158 int abs_chain_position
;
159 /// Is this TAP disabled after JTAG reset?
160 bool disabled_after_reset
;
161 /// Is this TAP currently enabled?
163 int ir_length
; /**< size of instruction register */
164 uint32_t ir_capture_value
;
165 uint8_t* expected
; /**< Capture-IR expected value */
166 uint32_t ir_capture_mask
;
167 uint8_t* expected_mask
; /**< Capture-IR expected mask */
169 bool hasidcode
; /* not all devices have idcode, we'll discover this during chain examination */
170 /**< device identification code */
172 /// Array of expected identification codes */
173 uint32_t* expected_ids
;
174 /// Number of expected identification codes
175 uint8_t expected_ids_cnt
;
177 /// current instruction
179 /// Bypass register selected
182 jtag_tap_event_action_t
*event_action
;
184 jtag_tap_t
* next_tap
;
187 void jtag_tap_init(jtag_tap_t
*tap
);
188 void jtag_tap_free(jtag_tap_t
*tap
);
190 extern jtag_tap_t
* jtag_all_taps(void);
191 extern const char *jtag_tap_name(const jtag_tap_t
*tap
);
192 extern jtag_tap_t
* jtag_tap_by_string(const char* dotted_name
);
193 extern jtag_tap_t
* jtag_tap_by_jim_obj(Jim_Interp
* interp
, Jim_Obj
* obj
);
194 extern jtag_tap_t
* jtag_tap_next_enabled(jtag_tap_t
* p
);
195 extern unsigned jtag_tap_count_enabled(void);
196 extern unsigned jtag_tap_count(void);
200 * - TRST_ASSERTED triggers two sets of callbacks, after operations to
201 * reset the scan chain -- via TMS+TCK signaling, or deasserting the
202 * nTRST signal -- are queued:
204 * + Callbacks in C code fire first, patching internal state
205 * + Then post-reset event scripts fire ... activating JTAG circuits
206 * via TCK cycles, exiting SWD mode via TMS sequences, etc
208 * During those callbacks, scan chain contents have not been validated.
209 * JTAG operations that address a specific TAP (primarily DR/IR scans)
210 * must *not* be queued.
212 * - TAP_EVENT_SETUP is reported after TRST_ASSERTED, and after the scan
213 * chain has been validated. JTAG operations including scans that
214 * target specific TAPs may be performed.
216 * - TAP_EVENT_ENABLE and TAP_EVENT_DISABLE implement TAP activation and
217 * deactivation outside the core using scripted code that understands
218 * the specific JTAG router type. They might be triggered indirectly
219 * from EVENT_SETUP operations.
223 JTAG_TAP_EVENT_SETUP
,
224 JTAG_TAP_EVENT_ENABLE
,
225 JTAG_TAP_EVENT_DISABLE
,
228 struct jtag_tap_event_action_s
230 enum jtag_event event
;
232 jtag_tap_event_action_t
* next
;
236 * Defines the function signature requide for JTAG event callback
237 * functions, which are added with jtag_register_event_callback()
238 * and removed jtag_unregister_event_callback().
239 * @param event The event to handle.
240 * @param prive A pointer to data that was passed to
241 * jtag_register_event_callback().
242 * @returns Must return ERROR_OK on success, or an error code on failure.
244 * @todo Change to return void or define a use for its return code.
246 typedef int (*jtag_event_handler_t
)(enum jtag_event event
, void* priv
);
248 extern int jtag_register_event_callback(jtag_event_handler_t f
, void *x
);
249 extern int jtag_unregister_event_callback(jtag_event_handler_t f
, void *x
);
251 extern int jtag_call_event_callbacks(enum jtag_event event
);
254 /// @returns The current JTAG speed setting.
255 int jtag_get_speed(void);
257 * Given a @a speed setting, use the interface @c speed_div callback to
258 * adjust the setting.
259 * @param speed The speed setting to convert back to readable KHz.
260 * @returns ERROR_OK if the interface has not been initialized or on success;
261 * otherwise, the error code produced by the @c speed_div callback.
263 int jtag_get_speed_readable(int *speed
);
265 * Set the JTAG speed. This routine will call the underlying
266 * interface @c speed callback, if the interface has been initialized.
267 * @param speed The new speed setting.
268 * @returns ERROR_OK during configuration or on success, or an error
269 * code returned from the interface @c speed callback.
271 int jtag_config_speed(int speed
);
274 /// Attempt to configure the interface for the specified KHz.
275 int jtag_config_khz(unsigned khz
);
277 * Attempt to enable RTCK/RCLK. If that fails, fallback to the
278 * specified frequency.
280 int jtag_config_rclk(unsigned fallback_speed_khz
);
281 /// Retreives the clock speed of the JTAG interface in KHz.
282 unsigned jtag_get_speed_khz(void);
287 RESET_HAS_TRST
= 0x1,
288 RESET_HAS_SRST
= 0x2,
289 RESET_TRST_AND_SRST
= 0x3,
290 RESET_SRST_PULLS_TRST
= 0x4,
291 RESET_TRST_PULLS_SRST
= 0x8,
292 RESET_TRST_OPEN_DRAIN
= 0x10,
293 RESET_SRST_PUSH_PULL
= 0x20,
294 RESET_SRST_NO_GATING
= 0x40,
297 enum reset_types
jtag_get_reset_config(void);
298 void jtag_set_reset_config(enum reset_types type
);
300 void jtag_set_nsrst_delay(unsigned delay
);
301 unsigned jtag_get_nsrst_delay(void);
303 void jtag_set_ntrst_delay(unsigned delay
);
304 unsigned jtag_get_ntrst_delay(void);
306 void jtag_set_nsrst_assert_width(unsigned delay
);
307 unsigned jtag_get_nsrst_assert_width(void);
309 void jtag_set_ntrst_assert_width(unsigned delay
);
310 unsigned jtag_get_ntrst_assert_width(void);
312 /// @returns The current state of TRST.
313 int jtag_get_trst(void);
314 /// @returns The current state of SRST.
315 int jtag_get_srst(void);
317 /// Enable or disable data scan verification checking.
318 void jtag_set_verify(bool enable
);
319 /// @returns True if data scan verification will be performed.
320 bool jtag_will_verify(void);
322 /// Enable or disable verification of IR scan checking.
323 void jtag_set_verify_capture_ir(bool enable
);
324 /// @returns True if IR scan verification will be performed.
325 bool jtag_will_verify_capture_ir(void);
328 * Initialize interface upon startup. Return a successful no-op upon
329 * subsequent invocations.
331 extern int jtag_interface_init(struct command_context_s
* cmd_ctx
);
333 /// Shutdown the JTAG interface upon program exit.
334 extern int jtag_interface_quit(void);
337 * Initialize JTAG chain using only a RESET reset. If init fails,
340 extern int jtag_init(struct command_context_s
* cmd_ctx
);
342 /// reset, then initialize JTAG chain
343 extern int jtag_init_reset(struct command_context_s
* cmd_ctx
);
344 extern int jtag_register_commands(struct command_context_s
* cmd_ctx
);
345 extern int jtag_init_inner(struct command_context_s
*cmd_ctx
);
349 * The JTAG interface can be implemented with a software or hardware fifo.
351 * TAP_DRSHIFT and TAP_IRSHIFT are illegal end states; however,
352 * TAP_DRSHIFT/IRSHIFT can be emulated as end states, by using longer
355 * Code that is relatively insensitive to the path taken through state
356 * machine (as long as it is JTAG compliant) can use @a endstate for
357 * jtag_add_xxx_scan(). Otherwise, the pause state must be specified as
358 * end state and a subsequent jtag_add_pathmove() must be issued.
362 * Generate an IR SCAN with a list of scan fields with one entry for
365 * If the input field list contains an instruction value for a TAP then
366 * that is used otherwise the TAP is set to bypass.
368 * TAPs for which no fields are passed are marked as bypassed for
369 * subsequent DR SCANs.
372 extern void jtag_add_ir_scan(int num_fields
, scan_field_t
* fields
, tap_state_t endstate
);
374 * The same as jtag_add_ir_scan except no verification is performed out
377 extern void jtag_add_ir_scan_noverify(int num_fields
, const scan_field_t
*fields
, tap_state_t state
);
379 * Duplicate the scan fields passed into the function into an IR SCAN
380 * command. This function assumes that the caller handles extra fields
383 extern void jtag_add_plain_ir_scan(int num_fields
, const scan_field_t
* fields
, tap_state_t endstate
);
387 * Set in_value to point to 32 bits of memory to scan into. This
388 * function is a way to handle the case of synchronous and asynchronous
391 * In the event of an asynchronous queue execution the queue buffer
392 * allocation method is used, for the synchronous case the temporary 32
393 * bits come from the input field itself.
395 extern void jtag_alloc_in_value32(scan_field_t
*field
);
398 * Generate a DR SCAN using the fields passed to the function.
399 * For connected TAPs, the function checks in_fields and uses fields
400 * specified there. For bypassed TAPs, the function generates a dummy
401 * 1-bit field. The bypass status of TAPs is set by jtag_add_ir_scan().
403 extern void jtag_add_dr_scan(int num_fields
, const scan_field_t
* fields
, tap_state_t endstate
);
404 /// A version of jtag_add_dr_scan() that uses the check_value/mask fields
405 extern void jtag_add_dr_scan_check(int num_fields
, scan_field_t
* fields
, tap_state_t endstate
);
407 * Duplicate the scan fields passed into the function into a DR SCAN
408 * command. Unlike jtag_add_dr_scan(), this function assumes that the
409 * caller handles extra fields for bypassed TAPs.
411 extern void jtag_add_plain_dr_scan(int num_fields
, const scan_field_t
* fields
, tap_state_t endstate
);
414 * Defines the type of data passed to the jtag_callback_t interface.
415 * The underlying type must allow storing an @c int or pointer type.
417 typedef intptr_t jtag_callback_data_t
;
420 * Defines a simple JTAG callback that can allow conversions on data
421 * scanned in from an interface.
423 * This callback should only be used for conversion that cannot fail.
424 * For conversion types or checks that can fail, use the more complete
425 * variant: jtag_callback_t.
427 typedef void (*jtag_callback1_t
)(jtag_callback_data_t data0
);
429 /// A simpler version of jtag_add_callback4().
430 extern void jtag_add_callback(jtag_callback1_t
, jtag_callback_data_t data0
);
435 * Defines the interface of the JTAG callback mechanism.
437 * @param in the pointer to the data clocked in
438 * @param data1 An integer big enough to use as an @c int or a pointer.
439 * @param data2 An integer big enough to use as an @c int or a pointer.
440 * @param data3 An integer big enough to use as an @c int or a pointer.
441 * @returns an error code
443 typedef int (*jtag_callback_t
)(jtag_callback_data_t data0
, jtag_callback_data_t data1
, jtag_callback_data_t data2
, jtag_callback_data_t data3
);
447 * This callback can be executed immediately the queue has been flushed.
449 * The JTAG queue can be executed synchronously or asynchronously.
450 * Typically for USB, the queue is executed asynchronously. For
451 * low-latency interfaces, the queue may be executed synchronously.
453 * The callback mechanism is very general and does not make many
454 * assumptions about what the callback does or what its arguments are.
455 * These callbacks are typically executed *after* the *entire* JTAG
456 * queue has been executed for e.g. USB interfaces, and they are
457 * guaranteeed to be invoked in the order that they were queued.
459 * If the execution of the queue fails before the callbacks, then --
460 * depending on driver implementation -- the callbacks may or may not be
461 * invoked. @todo Can we make this behavior consistent?
463 * The strange name is due to C's lack of overloading using function
466 * @param f The callback function to add.
467 * @param data0 Typically used to point to the data to operate on.
468 * Frequently this will be the data clocked in during a shift operation.
469 * @param data1 An integer big enough to use as an @c int or a pointer.
470 * @param data2 An integer big enough to use as an @c int or a pointer.
471 * @param data3 An integer big enough to use as an @c int or a pointer.
474 extern void jtag_add_callback4(jtag_callback_t f
, jtag_callback_data_t data0
,
475 jtag_callback_data_t data1
, jtag_callback_data_t data2
,
476 jtag_callback_data_t data3
);
480 * Run a TAP_RESET reset where the end state is TAP_RESET,
481 * regardless of the start state.
483 extern void jtag_add_tlr(void);
486 * Application code *must* assume that interfaces will
487 * implement transitions between states with different
488 * paths and path lengths through the state diagram. The
489 * path will vary across interface and also across versions
490 * of the same interface over time. Even if the OpenOCD code
491 * is unchanged, the actual path taken may vary over time
492 * and versions of interface firmware or PCB revisions.
494 * Use jtag_add_pathmove() when specific transition sequences
497 * Do not use jtag_add_pathmove() unless you need to, but do use it
500 * DANGER! If the target is dependent upon a particular sequence
501 * of transitions for things to work correctly(e.g. as a workaround
502 * for an errata that contradicts the JTAG standard), then pathmove
503 * must be used, even if some jtag interfaces happen to use the
504 * desired path. Worse, the jtag interface used for testing a
505 * particular implementation, could happen to use the "desired"
506 * path when transitioning to/from end
509 * A list of unambigious single clock state transitions, not
510 * all drivers can support this, but it is required for e.g.
511 * XScale and Xilinx support
513 * Note! TAP_RESET must not be used in the path!
515 * Note that the first on the list must be reachable
516 * via a single transition from the current state.
518 * All drivers are required to implement jtag_add_pathmove().
519 * However, if the pathmove sequence can not be precisely
520 * executed, an interface_jtag_add_pathmove() or jtag_execute_queue()
521 * must return an error. It is legal, but not recommended, that
522 * a driver returns an error in all cases for a pathmove if it
523 * can only implement a few transitions and therefore
524 * a partial implementation of pathmove would have little practical
527 * If an error occurs, jtag_error will contain one of these error codes:
528 * - ERROR_JTAG_NOT_STABLE_STATE -- The final state was not stable.
529 * - ERROR_JTAG_STATE_INVALID -- The path passed through TAP_RESET.
530 * - ERROR_JTAG_TRANSITION_INVALID -- The path includes invalid
533 extern void jtag_add_pathmove(int num_states
, const tap_state_t
* path
);
536 * jtag_add_statemove() moves from the current state to @a goal_state.
538 * @param goal_state The final TAP state.
539 * @return ERROR_OK on success, or an error code on failure.
541 * Moves from the current state to the goal \a state.
542 * Both states must be stable.
544 extern int jtag_add_statemove(tap_state_t goal_state
);
547 * Goes to TAP_IDLE (if we're not already there), cycle
548 * precisely num_cycles in the TAP_IDLE state, after which move
549 * to @a endstate (unless it is also TAP_IDLE).
551 * @param num_cycles Number of cycles in TAP_IDLE state. This argument
552 * may be 0, in which case this routine will navigate to @a endstate
554 * @param endstate The final state.
556 extern void jtag_add_runtest(int num_cycles
, tap_state_t endstate
);
559 * A reset of the TAP state machine can be requested.
561 * Whether tms or trst reset is used depends on the capabilities of
562 * the target and jtag interface(reset_config command configures this).
564 * srst can driver a reset of the TAP state machine and vice
567 * Application code may need to examine value of jtag_reset_config
568 * to determine the proper codepath
570 * DANGER! Even though srst drives trst, trst might not be connected to
571 * the interface, and it might actually be *harmful* to assert trst in this case.
573 * This is why combinations such as "reset_config srst_only srst_pulls_trst"
576 * only req_tlr_or_trst and srst can have a transition for a
577 * call as the effects of transitioning both at the "same time"
578 * are undefined, but when srst_pulls_trst or vice versa,
579 * then trst & srst *must* be asserted together.
581 extern void jtag_add_reset(int req_tlr_or_trst
, int srst
);
585 * Function jtag_set_end_state
587 * Set a global variable to \a state if \a state != TAP_INVALID.
589 * Return the value of the global variable.
592 extern tap_state_t
jtag_set_end_state(tap_state_t state
);
594 * Function jtag_get_end_state
596 * Return the value of the global variable for end state
599 extern tap_state_t
jtag_get_end_state(void);
600 extern void jtag_add_sleep(uint32_t us
);
604 * Function jtag_add_stable_clocks
605 * first checks that the state in which the clocks are to be issued is
606 * stable, then queues up clock_count clocks for transmission.
608 void jtag_add_clocks(int num_cycles
);
612 * For software FIFO implementations, the queued commands can be executed
613 * during this call or earlier. A sw queue might decide to push out
614 * some of the jtag_add_xxx() operations once the queue is "big enough".
616 * This fn will return an error code if any of the prior jtag_add_xxx()
617 * calls caused a failure, e.g. check failure. Note that it does not
618 * matter if the operation was executed *before* jtag_execute_queue(),
619 * jtag_execute_queue() will still return an error code.
621 * All jtag_add_xxx() calls that have in_handler != NULL will have been
622 * executed when this fn returns, but if what has been queued only
623 * clocks data out, without reading anything back, then JTAG could
624 * be running *after* jtag_execute_queue() returns. The API does
625 * not define a way to flush a hw FIFO that runs *after*
626 * jtag_execute_queue() returns.
628 * jtag_add_xxx() commands can either be executed immediately or
629 * at some time between the jtag_add_xxx() fn call and jtag_execute_queue().
631 extern int jtag_execute_queue(void);
633 /// same as jtag_execute_queue() but does not clear the error flag
634 extern void jtag_execute_queue_noclear(void);
636 /// @returns the number of times the scan queue has been flushed
637 int jtag_get_flush_queue_count(void);
639 /// Report Tcl event to all TAPs
640 void jtag_notify_event(enum jtag_event
);
643 /* can be implemented by hw + sw */
644 extern int jtag_power_dropout(int* dropout
);
645 extern int jtag_srst_asserted(int* srst_asserted
);
647 /* JTAG support functions */
650 * Execute jtag queue and check value with an optional mask.
651 * @param field Pointer to scan field.
652 * @param value Pointer to scan value.
653 * @param mask Pointer to scan mask; may be NULL.
654 * @returns Nothing, but calls jtag_set_error() on any error.
656 extern void jtag_check_value_mask(scan_field_t
*field
, uint8_t *value
, uint8_t *mask
);
658 extern void jtag_sleep(uint32_t us
);
661 * The JTAG subsystem defines a number of error codes,
662 * using codes between -100 and -199.
664 #define ERROR_JTAG_INIT_FAILED (-100)
665 #define ERROR_JTAG_INVALID_INTERFACE (-101)
666 #define ERROR_JTAG_NOT_IMPLEMENTED (-102)
667 #define ERROR_JTAG_TRST_ASSERTED (-103)
668 #define ERROR_JTAG_QUEUE_FAILED (-104)
669 #define ERROR_JTAG_NOT_STABLE_STATE (-105)
670 #define ERROR_JTAG_DEVICE_ERROR (-107)
671 #define ERROR_JTAG_STATE_INVALID (-108)
672 #define ERROR_JTAG_TRANSITION_INVALID (-109)
673 #define ERROR_JTAG_INIT_SOFT_FAIL (-110)
676 * jtag_add_dr_out() is a version of jtag_add_dr_scan() which
677 * only scans data out. It operates on 32 bit integers instead
678 * of 8 bit, which makes it a better impedance match with
679 * the calling code which often operate on 32 bit integers.
681 * Current or end_state can not be TAP_RESET. end_state can be TAP_INVALID
683 * num_bits[i] is the number of bits to clock out from value[i] LSB first.
685 * If the device is in bypass, then that is an error condition in
686 * the caller code that is not detected by this fn, whereas
687 * jtag_add_dr_scan() does detect it. Similarly if the device is not in
688 * bypass, data must be passed to it.
690 * If anything fails, then jtag_error will be set and jtag_execute() will
691 * return an error. There is no way to determine if there was a failure
692 * during this function call.
694 * This is an inline fn to speed up embedded hosts. Also note that
695 * interface_jtag_add_dr_out() can be a *small* inline function for
698 * There is no jtag_add_dr_outin() version of this fn that also allows
699 * clocking data back in. Patches gladly accepted!
701 extern void jtag_add_dr_out(jtag_tap_t
* tap
,
702 int num_fields
, const int* num_bits
, const uint32_t* value
,
703 tap_state_t end_state
);
707 * Set the current JTAG core execution error, unless one was set
708 * by a previous call previously. Driver or application code must
709 * use jtag_error_clear to reset jtag_error once this routine has been
710 * called with a non-zero error code.
712 void jtag_set_error(int error
);
713 /// @returns The current value of jtag_error
714 int jtag_get_error(void);
716 * Resets jtag_error to ERROR_OK, returning its previous value.
717 * @returns The previous value of @c jtag_error.
719 int jtag_error_clear(void);
722 * Return true if it's safe for a background polling task to access the
723 * JTAG scan chain. Polling may be explicitly disallowed, and is also
724 * unsafe while nTRST is active or the JTAG clock is gated off.,
726 bool is_jtag_poll_safe(void);
729 * Return flag reporting whether JTAG polling is disallowed.
731 bool jtag_poll_get_enabled(void);
734 * Assign flag reporting whether JTAG polling is disallowed.
736 void jtag_poll_set_enabled(bool value
);