diff options
| -rw-r--r-- | src/jtag/jtag.c | 52 |
1 files changed, 28 insertions, 24 deletions
diff --git a/src/jtag/jtag.c b/src/jtag/jtag.c index 8774bbba..0bc1c4ff 100644 --- a/src/jtag/jtag.c +++ b/src/jtag/jtag.c @@ -995,6 +995,27 @@ static void jtag_examine_chain_display(enum log_levels level, const char *msg, EXTRACT_MFG(idcode), EXTRACT_PART(idcode), EXTRACT_VER(idcode) ); } +/** + * This helper checks that remaining bits in the examined chain data are + * 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. + */ +static void jtag_examine_chain_end(u8 *idcodes, unsigned count, unsigned max) +{ + bool triggered = false; + for ( ; count < max - 31; count += 32) + { + u32 idcode = buf_get_u32(idcodes, count, 32); + // do not trigger the warning if the data looks good + if (!triggered && (idcode == 0x000000FF || idcode == 0xFFFFFFFF)) + continue; + LOG_WARNING("Unexpected idcode after end of chain: %d 0x%08x", + count, idcode); + triggered = true; + } +} + /* Try to examine chain layout according to IEEE 1149.1 §12 */ static int jtag_examine_chain(void) @@ -1029,32 +1050,15 @@ static int jtag_examine_chain(void) } else { - /* some devices, such as AVR will output all 1's instead of TDI - input value at end of chain. */ + /* + * 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 ((idcode == 0x000000FF)||(idcode == 0xFFFFFFFF)) { - int unexpected=0; - /* End of chain (invalid manufacturer ID) - * - * The JTAG examine is the very first thing that happens - * - * A single JTAG device requires only 64 bits to be read back correctly. - * - * The code below adds a check that the rest of the data scanned (640 bits) - * are all as expected. This helps diagnose/catch problems with the JTAG chain - * - * earlier and gives more helpful/explicit error messages. - */ - for (bit_count += 32; bit_count < (JTAG_MAX_CHAIN_SIZE * 32) - 31;bit_count += 32) - { - idcode = buf_get_u32(idcode_buffer, bit_count, 32); - if (unexpected||((idcode != 0x000000FF)&&(idcode != 0xFFFFFFFF))) - { - LOG_WARNING("Unexpected idcode after end of chain! %d 0x%08x", bit_count, idcode); - unexpected = 1; - } - } - + jtag_examine_chain_end(idcode_buffer, + bit_count + 32, JTAG_MAX_CHAIN_SIZE * 32); break; } |