diff options
| -rw-r--r-- | src/jtag/core.c | 77 |
1 files changed, 39 insertions, 38 deletions
diff --git a/src/jtag/core.c b/src/jtag/core.c index bf4a9cc7..f9ebb3fa 100644 --- a/src/jtag/core.c +++ b/src/jtag/core.c @@ -837,13 +837,18 @@ void jtag_sleep(uint32_t us) alive_sleep(us/1000); } -/// maximum number of JTAG devices expected in the chain +/* Maximum number of enabled JTAG devices we expect in the scan chain, + * plus one (to detect garbage at the end). Devices that don't support + * IDCODE take up fewer bits, possibly allowing a few more devices. + */ #define JTAG_MAX_CHAIN_SIZE 20 #define EXTRACT_MFG(X) (((X) & 0xffe) >> 1) #define EXTRACT_PART(X) (((X) & 0xffff000) >> 12) #define EXTRACT_VER(X) (((X) & 0xf0000000) >> 28) +#define END_OF_CHAIN_FLAG 0x000000ff + static int jtag_examine_chain_execute(uint8_t *idcode_buffer, unsigned num_idcode) { scan_field_t field = { @@ -855,7 +860,7 @@ static int jtag_examine_chain_execute(uint8_t *idcode_buffer, unsigned num_idcod // initialize to the end of chain ID value for (unsigned i = 0; i < JTAG_MAX_CHAIN_SIZE; i++) - buf_set_u32(idcode_buffer, i * 32, 32, 0x000000FF); + buf_set_u32(idcode_buffer, i * 32, 32, END_OF_CHAIN_FLAG); jtag_add_plain_dr_scan(1, &field, TAP_DRPAUSE); jtag_add_tlr(); @@ -899,7 +904,12 @@ static void jtag_examine_chain_display(enum log_levels level, const char *msg, static bool jtag_idcode_is_final(uint32_t idcode) { - return idcode == 0x000000FF || idcode == 0xFFFFFFFF; + /* + * Some devices, such as AVR8, will output all 1's instead + * of TDI input value at end of chain. Allow those values + * instead of failing. + */ + return idcode == END_OF_CHAIN_FLAG || idcode == 0xFFFFFFFF; } /** @@ -907,8 +917,9 @@ static bool jtag_idcode_is_final(uint32_t idcode) * all as expected, but a single JTAG device requires only 64 bits to be * read back correctly. This can help identify and diagnose problems * with the JTAG chain earlier, gives more helpful/explicit error messages. + * Returns TRUE iff garbage was found. */ -static void jtag_examine_chain_end(uint8_t *idcodes, unsigned count, unsigned max) +static bool jtag_examine_chain_end(uint8_t *idcodes, unsigned count, unsigned max) { bool triggered = false; for (; count < max - 31; count += 32) @@ -921,19 +932,14 @@ static void jtag_examine_chain_end(uint8_t *idcodes, unsigned count, unsigned ma count, (unsigned int)idcode); triggered = true; } + return triggered; } static bool jtag_examine_chain_match_tap(const struct jtag_tap_s *tap) { - if (0 == tap->expected_ids_cnt) - { - /// @todo Enable LOG_INFO to ask for reports about unknown TAP IDs. -#if 0 - LOG_INFO("Uknown JTAG TAP ID: 0x%08x", tap->idcode) - LOG_INFO("Please report the chip name and reported ID code to the openocd project"); -#endif + /* ignore expected BYPASS codes; warn otherwise */ + if (0 == tap->expected_ids_cnt && !tap->idcode) return true; - } /* Loop over the expected identification codes and test for a match */ uint8_t ii; @@ -944,7 +950,7 @@ static bool jtag_examine_chain_match_tap(const struct jtag_tap_s *tap) } /* If none of the expected ids matched, log an error */ - jtag_examine_chain_display(LOG_LVL_ERROR, "got", + jtag_examine_chain_display(LOG_LVL_ERROR, "UNEXPECTED", tap->dotted_name, tap->idcode); for (ii = 0; ii < tap->expected_ids_cnt; ii++) { @@ -962,10 +968,12 @@ static bool jtag_examine_chain_match_tap(const struct jtag_tap_s *tap) static int jtag_examine_chain(void) { uint8_t idcode_buffer[JTAG_MAX_CHAIN_SIZE * 4]; - unsigned device_count = 0; + unsigned bit_count; + /* DR scan to collect BYPASS or IDCODE register contents. + * Then make sure the scan data has both ones and zeroes. + */ jtag_examine_chain_execute(idcode_buffer, JTAG_MAX_CHAIN_SIZE); - if (!jtag_examine_chain_check(idcode_buffer, JTAG_MAX_CHAIN_SIZE)) return ERROR_JTAG_INIT_FAILED; @@ -977,7 +985,7 @@ static int jtag_examine_chain(void) return ERROR_JTAG_INIT_FAILED; } - for (unsigned bit_count = 0; + for (bit_count = 0; tap && bit_count < (JTAG_MAX_CHAIN_SIZE * 32) - 31; tap = jtag_tap_next_enabled(tap)) { @@ -995,26 +1003,13 @@ static int jtag_examine_chain(void) } else { + /* Friendly devices support IDCODE */ tap->hasidcode = true; - - /* - * End of chain (invalid manufacturer ID) some devices, such - * as AVR will output all 1's instead of TDI input value at - * end of chain. - */ - if (jtag_idcode_is_final(idcode)) - { - jtag_examine_chain_end(idcode_buffer, - bit_count + 32, JTAG_MAX_CHAIN_SIZE * 32); - break; - } - jtag_examine_chain_display(LOG_LVL_INFO, "tap/device found", tap->dotted_name, idcode); bit_count += 32; } - device_count++; tap->idcode = idcode; // ensure the TAP ID does matches what was expected @@ -1022,14 +1017,20 @@ static int jtag_examine_chain(void) return ERROR_JTAG_INIT_FAILED; } - /* see if number of discovered devices matches configuration */ - if (device_count != jtag_tap_count_enabled()) - { - LOG_ERROR("number of discovered devices in JTAG chain (%i) " - "does not match (enabled) configuration (%i), total taps: %d", - device_count, jtag_tap_count_enabled(), jtag_tap_count()); - LOG_ERROR("check the config file and ensure proper JTAG communication" - " (connections, speed, ...)"); + /* Fail if too many TAPs were enabled for us to verify them all. */ + if (tap) { + LOG_ERROR("Too many TAPs enabled; '%s' ignored.", + tap->dotted_name); + return ERROR_JTAG_INIT_FAILED; + } + + /* After those IDCODE or BYPASS register values should be + * only the data we fed into the scan chain. + */ + if (jtag_examine_chain_end(idcode_buffer, bit_count, + 8 * sizeof(idcode_buffer))) { + LOG_ERROR("double-check your JTAG setup (interface, " + "speed, TAPs, ...)"); return ERROR_JTAG_INIT_FAILED; } |