Some jtag_add_reset() cleanup:
- Track whether TRST and/or SRST actually change:
* If they're not changing, don't ask the JTAG adapter to do anything!
(JTAG TCK/TMS ops might still be used to enter TAP_RESET though.)
* Don't change their recorded values until after the adapter says it
did so ... so fault paths can't leave corrupt state.
* Detect and report jtag_execute_queue() failure mode
* Only emit messages saying what really changed; this includes adding
an omitted "deasserted TRST" message.
* Only apply delays after deasserting SRST/TRST if we *DID* deassert!
- Messages say "TLR" not "RESET", to be less confusing; there are many
kinds of reset. (Though "TLR" isn't quite ideal either, since it's
the name of the TAP state being entered by TMS+TCK or TRST; it's at
least non-ambiguous in context.)
So the main effect is to do only the work this routine was told to do;
and to have debug messaging make more sense.
---
src/jtag/core.c | 104 ++++++++++++++++++++++++++++++++----------------------
1 file changed, 62 insertions(+), 42 deletions(-)
--- a/src/jtag/core.c
+++ b/src/jtag/core.c
@@ -60,11 +60,15 @@ static int jtag_error = ERROR_OK;
static const char *jtag_event_strings[] =
{
- [JTAG_TRST_ASSERTED] = "JTAG controller reset (RESET or TRST)",
+ [JTAG_TRST_ASSERTED] = "JTAG controller reset (TLR or TRST)",
[JTAG_TAP_EVENT_ENABLE] = "TAP enabled",
[JTAG_TAP_EVENT_DISABLE] = "TAP disabled",
};
+/*
+ * JTAG adapters must initialize with TRST and SRST de-asserted
+ * (they're negative logic, so that means *high*)
+ */
static int jtag_trst = 0;
static int jtag_srst = 0;
@@ -590,6 +594,8 @@ void jtag_add_clocks(int num_cycles)
void jtag_add_reset(int req_tlr_or_trst, int req_srst)
{
int trst_with_tlr = 0;
+ int new_srst;
+ int new_trst = 0;
/* FIX!!! there are *many* different cases here. A better
* approach is needed for legal combinations of transitions...
@@ -634,58 +640,72 @@ void jtag_add_reset(int req_tlr_or_trst,
{
if (!trst_with_tlr && (jtag_reset_config & RESET_HAS_TRST))
{
- jtag_trst = 1;
+ new_trst = 1;
} else
{
trst_with_tlr = 1;
}
- } else
- {
- jtag_trst = 0;
}
- jtag_srst = req_srst;
+ new_srst = req_srst;
- int retval = interface_jtag_add_reset(jtag_trst, jtag_srst);
- if (retval != ERROR_OK)
- {
- jtag_set_error(retval);
- return;
- }
- jtag_execute_queue();
+ /* Maybe change TRST and/or SRST signal state */
+ if (jtag_srst != new_srst || jtag_trst != new_trst) {
+ int retval;
- if (jtag_srst)
- {
- LOG_DEBUG("SRST line asserted");
+ retval = interface_jtag_add_reset(new_trst, new_srst);
+ if (retval != ERROR_OK)
+ jtag_set_error(retval);
+ else
+ retval = jtag_execute_queue();
+
+ if (retval != ERROR_OK) {
+ LOG_ERROR("TRST/SRST error %d", retval);
+ return;
+ }
}
- else
- {
- LOG_DEBUG("SRST line released");
- if (jtag_nsrst_delay)
- jtag_add_sleep(jtag_nsrst_delay * 1000);
+
+ /* SRST resets everything hooked up to that signal */
+ if (jtag_srst != new_srst) {
+ jtag_srst = new_srst;
+ if (jtag_srst)
+ LOG_DEBUG("SRST line asserted");
+ else {
+ LOG_DEBUG("SRST line released");
+ if (jtag_nsrst_delay)
+ jtag_add_sleep(jtag_nsrst_delay * 1000);
+ }
}
- if (trst_with_tlr)
- {
- LOG_DEBUG("JTAG reset with RESET instead of TRST");
+ /* Maybe enter the JTAG TAP_RESET state ...
+ * - using only TMS, TCK, and the JTAG state machine
+ * - or else more directly, using TRST
+ *
+ * TAP_RESET should be invisible to non-debug parts of the system.
+ */
+ if (trst_with_tlr) {
+ LOG_DEBUG("JTAG reset with TLR instead of TRST");
jtag_set_end_state(TAP_RESET);
jtag_add_tlr();
- return;
- }
- if (jtag_trst)
- {
- /* we just asserted nTRST, so we're now in Test-Logic-Reset,
- * and inform possible listeners about this
- */
- LOG_DEBUG("TRST line asserted");
- tap_set_state(TAP_RESET);
- jtag_call_event_callbacks(JTAG_TRST_ASSERTED);
- }
- else
- {
- if (jtag_ntrst_delay)
- jtag_add_sleep(jtag_ntrst_delay * 1000);
+ } else if (jtag_trst != new_trst) {
+ jtag_trst = new_trst;
+ if (jtag_trst) {
+ /* we just asserted nTRST, so we're now in TAP_RESET;
+ * inform possible listeners about this
+ *
+ * REVISIT asserting TRST is less significant than
+ * being in TAP_RESET ... both entries (TRST, TLR)
+ * should trigger a callback.
+ */
+ LOG_DEBUG("TRST line asserted");
+ tap_set_state(TAP_RESET);
+ jtag_call_event_callbacks(JTAG_TRST_ASSERTED);
+ } else {
+ LOG_DEBUG("TRST line released");
+ if (jtag_ntrst_delay)
+ jtag_add_sleep(jtag_ntrst_delay * 1000);
+ }
}
}
@@ -1232,11 +1252,11 @@ int jtag_init_reset(struct command_conte
if ((retval = jtag_interface_init(cmd_ctx)) != ERROR_OK)
return retval;
- LOG_DEBUG("Trying to bring the JTAG controller to life by asserting
TRST / RESET");
+ LOG_DEBUG("Trying to bring the JTAG controller to life by asserting
TRST / TLR");
/* Reset can happen after a power cycle.
*
- * Ideally we would only assert TRST or run RESET before the target
reset.
+ * Ideally we would only assert TRST or run TLR before the target reset.
*
* However w/srst_pulls_trst, trst is asserted together with the target
* reset whether we want it or not.
@@ -1249,7 +1269,7 @@ int jtag_init_reset(struct command_conte
* NB! order matters!!!! srst *can* disconnect JTAG circuitry
*
*/
- jtag_add_reset(1, 0); /* RESET or TRST */
+ jtag_add_reset(1, 0); /* TAP_RESET, using TMS+TCK or TRST */
if (jtag_reset_config & RESET_HAS_SRST)
{
jtag_add_reset(1, 1);
Some jtag_add_reset() cleanup:
- Track whether TRST and/or SRST actually change:
* If they're not changing, don't ask the JTAG adapter to do anything!
(JTAG TCK/TMS ops might still be used to enter TAP_RESET though.)
* Don't change their recorded values until after the adapter says it
did so ... so fault paths can't leave corrupt state.
* Detect and report jtag_execute_queue() failure mode
* Only emit messages saying what really changed; this includes adding
an omitted "deasserted TRST" message.
* Only apply delays after deasserting SRST/TRST if we *DID* deassert!
- Messages say "TLR" not "RESET", to be less confusing; there are many
kinds of reset. (Though "TLR" isn't quite ideal either, since it's
the name of the TAP state being entered by TMS+TCK or TRST; it's at
least non-ambiguous in context.)
So the main effect is to do only the work this routine was told to do;
and to have debug messaging make more sense.
---
src/jtag/core.c | 104 ++++++++++++++++++++++++++++++++----------------------
1 file changed, 62 insertions(+), 42 deletions(-)
--- a/src/jtag/core.c
+++ b/src/jtag/core.c
@@ -60,11 +60,15 @@ static int jtag_error = ERROR_OK;
static const char *jtag_event_strings[] =
{
- [JTAG_TRST_ASSERTED] = "JTAG controller reset (RESET or TRST)",
+ [JTAG_TRST_ASSERTED] = "JTAG controller reset (TLR or TRST)",
[JTAG_TAP_EVENT_ENABLE] = "TAP enabled",
[JTAG_TAP_EVENT_DISABLE] = "TAP disabled",
};
+/*
+ * JTAG adapters must initialize with TRST and SRST de-asserted
+ * (they're negative logic, so that means *high*)
+ */
static int jtag_trst = 0;
static int jtag_srst = 0;
@@ -590,6 +594,8 @@ void jtag_add_clocks(int num_cycles)
void jtag_add_reset(int req_tlr_or_trst, int req_srst)
{
int trst_with_tlr = 0;
+ int new_srst;
+ int new_trst = 0;
/* FIX!!! there are *many* different cases here. A better
* approach is needed for legal combinations of transitions...
@@ -634,58 +640,72 @@ void jtag_add_reset(int req_tlr_or_trst,
{
if (!trst_with_tlr && (jtag_reset_config & RESET_HAS_TRST))
{
- jtag_trst = 1;
+ new_trst = 1;
} else
{
trst_with_tlr = 1;
}
- } else
- {
- jtag_trst = 0;
}
- jtag_srst = req_srst;
+ new_srst = req_srst;
- int retval = interface_jtag_add_reset(jtag_trst, jtag_srst);
- if (retval != ERROR_OK)
- {
- jtag_set_error(retval);
- return;
- }
- jtag_execute_queue();
+ /* Maybe change TRST and/or SRST signal state */
+ if (jtag_srst != new_srst || jtag_trst != new_trst) {
+ int retval;
- if (jtag_srst)
- {
- LOG_DEBUG("SRST line asserted");
+ retval = interface_jtag_add_reset(new_trst, new_srst);
+ if (retval != ERROR_OK)
+ jtag_set_error(retval);
+ else
+ retval = jtag_execute_queue();
+
+ if (retval != ERROR_OK) {
+ LOG_ERROR("TRST/SRST error %d", retval);
+ return;
+ }
}
- else
- {
- LOG_DEBUG("SRST line released");
- if (jtag_nsrst_delay)
- jtag_add_sleep(jtag_nsrst_delay * 1000);
+
+ /* SRST resets everything hooked up to that signal */
+ if (jtag_srst != new_srst) {
+ jtag_srst = new_srst;
+ if (jtag_srst)
+ LOG_DEBUG("SRST line asserted");
+ else {
+ LOG_DEBUG("SRST line released");
+ if (jtag_nsrst_delay)
+ jtag_add_sleep(jtag_nsrst_delay * 1000);
+ }
}
- if (trst_with_tlr)
- {
- LOG_DEBUG("JTAG reset with RESET instead of TRST");
+ /* Maybe enter the JTAG TAP_RESET state ...
+ * - using only TMS, TCK, and the JTAG state machine
+ * - or else more directly, using TRST
+ *
+ * TAP_RESET should be invisible to non-debug parts of the system.
+ */
+ if (trst_with_tlr) {
+ LOG_DEBUG("JTAG reset with TLR instead of TRST");
jtag_set_end_state(TAP_RESET);
jtag_add_tlr();
- return;
- }
- if (jtag_trst)
- {
- /* we just asserted nTRST, so we're now in Test-Logic-Reset,
- * and inform possible listeners about this
- */
- LOG_DEBUG("TRST line asserted");
- tap_set_state(TAP_RESET);
- jtag_call_event_callbacks(JTAG_TRST_ASSERTED);
- }
- else
- {
- if (jtag_ntrst_delay)
- jtag_add_sleep(jtag_ntrst_delay * 1000);
+ } else if (jtag_trst != new_trst) {
+ jtag_trst = new_trst;
+ if (jtag_trst) {
+ /* we just asserted nTRST, so we're now in TAP_RESET;
+ * inform possible listeners about this
+ *
+ * REVISIT asserting TRST is less significant than
+ * being in TAP_RESET ... both entries (TRST, TLR)
+ * should trigger a callback.
+ */
+ LOG_DEBUG("TRST line asserted");
+ tap_set_state(TAP_RESET);
+ jtag_call_event_callbacks(JTAG_TRST_ASSERTED);
+ } else {
+ LOG_DEBUG("TRST line released");
+ if (jtag_ntrst_delay)
+ jtag_add_sleep(jtag_ntrst_delay * 1000);
+ }
}
}
@@ -1232,11 +1252,11 @@ int jtag_init_reset(struct command_conte
if ((retval = jtag_interface_init(cmd_ctx)) != ERROR_OK)
return retval;
- LOG_DEBUG("Trying to bring the JTAG controller to life by asserting TRST / RESET");
+ LOG_DEBUG("Trying to bring the JTAG controller to life by asserting TRST / TLR");
/* Reset can happen after a power cycle.
*
- * Ideally we would only assert TRST or run RESET before the target reset.
+ * Ideally we would only assert TRST or run TLR before the target reset.
*
* However w/srst_pulls_trst, trst is asserted together with the target
* reset whether we want it or not.
@@ -1249,7 +1269,7 @@ int jtag_init_reset(struct command_conte
* NB! order matters!!!! srst *can* disconnect JTAG circuitry
*
*/
- jtag_add_reset(1, 0); /* RESET or TRST */
+ jtag_add_reset(1, 0); /* TAP_RESET, using TMS+TCK or TRST */
if (jtag_reset_config & RESET_HAS_SRST)
{
jtag_add_reset(1, 1);
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