diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/jtag/core.c | 114 |
1 files changed, 102 insertions, 12 deletions
diff --git a/src/jtag/core.c b/src/jtag/core.c index 08cfe43..8bb45bc 100644 --- a/src/jtag/core.c +++ b/src/jtag/core.c @@ -890,6 +890,9 @@ void jtag_sleep(uint32_t us) */ #define END_OF_CHAIN_FLAG 0x000000ff +/* a larger IR length than we ever expect to autoprobe */ +#define JTAG_IRLEN_MAX 60 + static int jtag_examine_chain_execute(uint8_t *idcode_buffer, unsigned num_idcode) { scan_field_t field = { @@ -1027,6 +1030,8 @@ static int jtag_examine_chain(void) uint8_t idcode_buffer[JTAG_MAX_CHAIN_SIZE * 4]; unsigned bit_count; int retval; + int tapcount = 0; + bool autoprobe = false; /* DR scan to collect BYPASS or IDCODE register contents. * Then make sure the scan data has both ones and zeroes. @@ -1040,11 +1045,9 @@ static int jtag_examine_chain(void) /* point at the 1st tap */ jtag_tap_t *tap = jtag_tap_next_enabled(NULL); - if (tap == NULL) - { - LOG_ERROR("JTAG: No taps enabled?"); - return ERROR_JTAG_INIT_FAILED; - } + + if (!tap) + autoprobe = true; for (bit_count = 0; tap && bit_count < (JTAG_MAX_CHAIN_SIZE * 32) - 31; @@ -1086,6 +1089,59 @@ static int jtag_examine_chain(void) return ERROR_JTAG_INIT_FAILED; } + /* if autoprobing, the tap list is still empty ... populate it! */ + while (autoprobe && bit_count < (JTAG_MAX_CHAIN_SIZE * 32) - 31) { + uint32_t idcode; + char buf[12]; + + /* Is there another TAP? */ + idcode = buf_get_u32(idcode_buffer, bit_count, 32); + if (jtag_idcode_is_final(idcode)) + break; + + /* Default everything in this TAP except IR length. + * + * REVISIT create a jtag_alloc(chip, tap) routine, and + * share it with jim_newtap_cmd(). + */ + tap = calloc(1, sizeof *tap); + if (!tap) + return ERROR_FAIL; + + sprintf(buf, "auto%d", tapcount++); + tap->chip = strdup(buf); + tap->tapname = strdup("tap"); + + sprintf(buf, "%s.%s", tap->chip, tap->tapname); + tap->dotted_name = strdup(buf); + + /* tap->ir_length == 0 ... signifying irlen autoprobe */ + tap->ir_capture_mask = 0x03; + tap->ir_capture_value = 0x01; + + tap->enabled = true; + + if ((idcode & 1) == 0) { + bit_count += 1; + tap->hasidcode = false; + } else { + bit_count += 32; + tap->hasidcode = true; + tap->idcode = idcode; + + tap->expected_ids_cnt = 1; + tap->expected_ids = malloc(sizeof(uint32_t)); + tap->expected_ids[0] = idcode; + } + + LOG_WARNING("AUTO %s - use \"jtag newtap " + "%s %s -expected-id 0x%8.8" PRIx32 " ...\"", + tap->dotted_name, tap->chip, tap->tapname, + tap->idcode); + + jtag_tap_init(tap); + } + /* After those IDCODE or BYPASS register values should be * only the data we fed into the scan chain. */ @@ -1120,10 +1176,13 @@ static int jtag_validate_ircapture(void) int chain_pos = 0; int retval; + /* when autoprobing, accomodate huge IR lengths */ for (tap = NULL, total_ir_length = 0; (tap = jtag_tap_next_enabled(tap)) != NULL; - total_ir_length += tap->ir_length) - continue; + total_ir_length += tap->ir_length) { + if (tap->ir_length == 0) + total_ir_length += JTAG_IRLEN_MAX; + } /* increase length to add 2 bit sentinel after scan */ total_ir_length += 2; @@ -1156,6 +1215,25 @@ static int jtag_validate_ircapture(void) break; } + /* If we're autoprobing, guess IR lengths. They must be at + * least two bits. Guessing will fail if (a) any TAP does + * not conform to the JTAG spec; or (b) when the upper bits + * captured from some conforming TAP are nonzero. + * + * REVISIT alternative approach: escape to some tcl code + * which could provide more knowledge, based on IDCODE; and + * only guess when that has no success. + */ + if (tap->ir_length == 0) { + tap->ir_length = 2; + while ((val = buf_get_u32(ir_test, chain_pos, + tap->ir_length + 1)) == 1) { + tap->ir_length++; + } + LOG_WARNING("AUTO %s - use \"... -irlen %d\"", + jtag_tap_name(tap), tap->ir_length); + } + /* Validate the two LSBs, which must be 01 per JTAG spec. * * Or ... more bits could be provided by TAP declaration. @@ -1207,9 +1285,8 @@ void jtag_tap_init(jtag_tap_t *tap) unsigned ir_len_bits; unsigned ir_len_bytes; - assert(0 != tap->ir_length); - - ir_len_bits = tap->ir_length; + /* if we're autoprobing, cope with potentially huge ir_length */ + ir_len_bits = tap->ir_length ? : JTAG_IRLEN_MAX; ir_len_bytes = CEIL(ir_len_bits, 8); tap->expected = calloc(1, ir_len_bytes); @@ -1302,8 +1379,21 @@ int jtag_init_inner(struct command_context_s *cmd_ctx) tap = jtag_tap_next_enabled(NULL); if (tap == NULL) { - LOG_ERROR("There are no enabled taps?"); - return ERROR_JTAG_INIT_FAILED; + /* Once JTAG itself is properly set up, and the scan chain + * isn't absurdly large, IDCODE autoprobe should work fine. + * + * But ... IRLEN autoprobe can fail even on systems which + * are fully conformant to JTAG. Also, JTAG setup can be + * quite finicky on some systems. + * + * REVISIT: if TAP autoprobe works OK, then in many cases + * we could escape to tcl code and set up targets based on + * the TAP's IDCODE values. + */ + LOG_WARNING("There are no enabled taps. " + "AUTO PROBING MIGHT NOT WORK!!"); + + /* REVISIT default clock will often be too fast ... */ } jtag_add_tlr(); |