diff options
Diffstat (limited to 'src/device/dram/ddr3.c')
| -rw-r--r-- | src/device/dram/ddr3.c | 53 |
1 files changed, 37 insertions, 16 deletions
diff --git a/src/device/dram/ddr3.c b/src/device/dram/ddr3.c index cb5b685d10..b3bcd680fe 100644 --- a/src/device/dram/ddr3.c +++ b/src/device/dram/ddr3.c @@ -46,6 +46,24 @@ int dimm_is_registered(enum spd_dimm_type type) return 0; } +static u16 crc16(const u8 *ptr, int n_crc) +{ + int i; + u16 crc = 0; + + while (--n_crc >= 0) { + crc = (crc ^ (int)*ptr++) << 8; + for (i = 0; i < 8; ++i) + if (crc & 0x8000) { + crc = (crc << 1) ^ 0x1021; + } else { + crc = crc << 1; + } + } + + return crc; +} + /** * \brief Calculate the CRC of a DDR3 SPD * @@ -56,9 +74,7 @@ int dimm_is_registered(enum spd_dimm_type type) */ u16 spd_ddr3_calc_crc(u8 *spd, int len) { - int n_crc, i; - u8 *ptr; - u16 crc; + int n_crc; /* Find the number of bytes covered by CRC */ if (spd[0] & 0x80) { @@ -71,19 +87,24 @@ u16 spd_ddr3_calc_crc(u8 *spd, int len) /* Not enough bytes available to get the CRC */ return 0; - /* Compute the CRC */ - crc = 0; - ptr = spd; - while (--n_crc >= 0) { - crc = crc ^ (int)*ptr++ << 8; - for (i = 0; i < 8; ++i) - if (crc & 0x8000) { - crc = crc << 1 ^ 0x1021; - } else { - crc = crc << 1; - } - } - return crc; + return crc16(spd, n_crc); +} + +/** + * \brief Calculate the CRC of a DDR3 SPD unique identifier + * + * @param spd pointer to raw SPD data + * @param len length of data in SPD + * + * @return the CRC of SPD data bytes 117..127, or 0 when spd data is truncated. + */ +u16 spd_ddr3_calc_unique_crc(u8 *spd, int len) +{ + if (len < (117 + 11)) + /* Not enough bytes available to get the CRC */ + return 0; + + return crc16(&spd[117], 11); } /** |