diff options
Diffstat (limited to 'src/soc/amd/common/block/spi/fch_spi_ctrl.c')
| -rw-r--r-- | src/soc/amd/common/block/spi/fch_spi_ctrl.c | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/src/soc/amd/common/block/spi/fch_spi_ctrl.c b/src/soc/amd/common/block/spi/fch_spi_ctrl.c index 4299e4f5c3..a7d9c77e12 100644 --- a/src/soc/amd/common/block/spi/fch_spi_ctrl.c +++ b/src/soc/amd/common/block/spi/fch_spi_ctrl.c @@ -278,12 +278,26 @@ static int fch_spi_flash_probe(const struct spi_slave *spi, struct spi_flash *fl printk(BIOS_SPEW, "\n"); } - /* count the number of continuation bytes */ - for (shift = 0, idp = idcode; shift < IDCODE_CONT_LEN && *idp == 0x7f; - ++shift, ++idp) - continue; + /* + * All solid state devices have vendor id defined by JEDEC specification JEP106, + * which originally allocated only 7 bits for it plus parity. When number of + * vendors exploded beyond 126, a banking proposition came maintaining + * compatibility with older vendors while allowing for 4 extra bits (16 banks) + * through the introduction of the concept "Continuation Code", denoted by the + * byte value of 0x7f. + * Examples: + * 0xfe, 0x60, 0x18, 0x00, 0x00, 0x00 => vendor 0xfe of bank o + * 0x7f, 0x7f, 0xfe, 0x60, 0x18, 0x00 => vendor 0xfe of bank 2 + * count the number of continuation code bytes + */ + for (shift = 0, idp = idcode; *idp == IDCODE_CONT_CODE; ++shift, ++idp) { + if (shift < IDCODE_CONT_LEN) + continue; + printk(BIOS_ERR, "unsupported ID code bank\n"); + return -1; + } - printk(BIOS_INFO, "Manufacturer: %02x\n", *idp); + printk(BIOS_INFO, "Manufacturer: %02x on bank %d\n", *idp, shift); /* search the table for matches in shift and id */ for (i = 0; i < table_size; ++i) { |