This adds CRC-16 calculation, needed to correctly detect DDR3 SPD EEPROMs. --- a/prog/detect/sensors-detect +++ b/prog/detect/sensors-detect @@ -5265,18 +5265,43 @@ # Registers used: # 0-63: SPD Data and Checksum +# 0-127: SPD data and CRC (DDR3) sub eeprom_detect { my ($file, $addr) = @_; + my $device_type = i2c_smbus_read_byte_data($file, 2); my $checksum = 0; # Check the checksum for validity (works for most DIMMs and RIMMs) - for (my $i = 0; $i <= 62; $i++) { - $checksum += i2c_smbus_read_byte_data($file, $i); + if ($device_type >= 1 and $device_type <= 10) { + for (my $i = 0; $i <= 62; $i++) { + $checksum += i2c_smbus_read_byte_data($file, $i); + } + $checksum &= 255; + + return 8 if $checksum == i2c_smbus_read_byte_data($file, 63); + } elsif ($device_type == 11) { + # see JEDEC 21-C 4.1.2.11 2.4 + my $crc_coverage = i2c_smbus_read_byte_data($file, 0); + $crc_coverage = ($crc_coverage & 0x80) ? 117 : 126; + for (my $i = 0; $i < $crc_coverage; $i++) { + $checksum ^= i2c_smbus_read_byte_data($file, $i) << 8; + for (my $bit = 0; $bit < 8; $bit++) { + if ($checksum & 0x8000) { + $checksum = ($checksum << 1) ^ 0x1021; + } else { + $checksum <<= 1; + } + } + } + $checksum &= 0xffff; + + return 8 if ($checksum & 0xff) == i2c_smbus_read_byte_data($file, 126) and + ($checksum >> 8) == i2c_smbus_read_byte_data($file, 127); + + # note: if bit 7 of byte 32 is set, a jc42 sensor is at $addr-0x38 } - $checksum &= 255; - return 8 if $checksum == i2c_smbus_read_byte_data($file, 63); return; } _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors