diff options
| -rw-r--r-- | src/jtag/core.c | 104 |
1 files changed, 62 insertions, 42 deletions
diff --git a/src/jtag/core.c b/src/jtag/core.c index d9cdffa5..06e015c4 100644 --- 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; @@ -581,6 +585,8 @@ 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... @@ -625,58 +631,72 @@ void jtag_add_reset(int req_tlr_or_trst, int req_srst) { 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); + } } } @@ -1223,11 +1243,11 @@ int jtag_init_reset(struct command_context_s *cmd_ctx) 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. @@ -1240,7 +1260,7 @@ int jtag_init_reset(struct command_context_s *cmd_ctx) * 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); |