From: David Brownell Date: Mon, 26 Oct 2009 07:36:03 +0000 (-0700) Subject: JTAG: simple autoprobing X-Git-Tag: v0.3.0-rc0~26 X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=6cb1d10cdad509939e3decf089e08c289d85d5cf;p=openocd JTAG: simple autoprobing This patch adds basic autoprobing support for the JTAG scan chains which cooperate. To use, you can invoke OpenOCD with just: - interface spec: "-f interface/...cfg" - possibly with "-c 'reset_config ...'" for SRST/TRST - possibly with "-c 'jtag_khz ...'" for the JTAG clock Then set up config files matching the reported TAPs. It doesn't declare targets ... just TAPs. So facilities above the JTAG and SVF/XSVF levels won't be available without a real config; this is almost purely a way to generate diagnostics. Autoprobe was successful with most boards I tested, except ones incorporating C55x DSPs (which don't cooperate with this scheme for IR length autodetection). Here's what one multi-TAP chip reported, with the "Warn:" prefixes removed: clock speed 500 kHz There are no enabled taps. AUTO PROBING MIGHT NOT WORK!! AUTO auto0.tap - use "jtag newtap auto0 tap -expected-id 0x2b900f0f ..." AUTO auto1.tap - use "jtag newtap auto1 tap -expected-id 0x07926001 ..." AUTO auto2.tap - use "jtag newtap auto2 tap -expected-id 0x0b73b02f ..." AUTO auto0.tap - use "... -irlen 4" AUTO auto1.tap - use "... -irlen 4" AUTO auto2.tap - use "... -irlen 6" no gdb ports allocated as no target has been specified The patch tweaks IR setup a bit, so we can represent TAPs with undeclared IR length. Signed-off-by: David Brownell --- diff --git a/TODO b/TODO index 6f9c7494..f567a82f 100644 --- a/TODO +++ b/TODO @@ -55,8 +55,10 @@ directly in minidriver API for better embedded host performance. The following tasks have been suggested for adding new core JTAG support: -- autodetect devices present on the scan chain - - implement 'discover_taps' command +- Improve autodetection of TAPs by supporting tcl escape procedures that + can configure discovered TAPs based on IDCODE value ... they could: + - Remove guessing for irlen + - Allow non-default irmask/ircapture values - SPI/UART emulation: - (ab)use bit-banging JTAG interfaces to emulate SPI/UART - allow SPI to program flash, MCUs, etc. @@ -94,6 +96,8 @@ interface support: - FT2232 (libftdi): - make performance comparable to alternatives (on Win32, D2XX is faster) - make usability comparable to alternatives +- Autodetect USB based adapters; this should be easy on Linux. If there's + more than one, list the options; otherwise, just select that one. The following tasks have been suggested for adding new JTAG interfaces: @@ -133,6 +137,7 @@ Once the above are completed: @section thelisttargets Target Support +- Many common ARM cores could be autodetected using IDCODE - general layer cleanup: @par https://lists.berlios.de/pipermail/openocd-development/2009-May/006590.html - regression: "reset halt" between 729(works) and 788(fails): @par diff --git a/src/jtag/core.c b/src/jtag/core.c index 08cfe436..8bb45bcd 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();