intel1155_ecc_check2.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <stdint.h>

/*
Interpretation of Register based on Intel documentation:
http://www.intel.in/content/dam/www/public/us/en/documents/datasheets/xeon-core-communication-infrastructure-datasheet-vol-1.pdf
Chapter 11.9 "MAD_DIMM_CH0 - Address Decode Channel 0"
Page 158 ff.
*/


#define MEM_START       0xFED10000
#define FILESIZE        32*1024


int decode_channel(char* mem_mad_dimm_chx)
    {
    uint32_t mad_dimm_chx= *( (uint32_t *) mem_mad_dimm_chx);

    // DIMM A is allways the larger one, is it because of that swapped
    // Bit 16
    printf("  DIMM A&B swapped: %u\n", (mad_dimm_chx & (1<<16)) > 0 );

    // Size of DIMM 256 MB multiples
    // DIMM A: Bits 7:0
    printf("  DIMM A Size:      %u MB\n", ((mad_dimm_chx & (255<<0))>>0) * 256 );
    // DIMM B: Bits 15:8
    printf("  DIMM B Size:      %u MB\n", ((mad_dimm_chx & (255<<8))>>8) * 256 );

    // Number of ranks (0 = single, 1 = dual)
    // DIMM A: bit 17
    printf("  DIMM A dual rank: %u\n", (mad_dimm_chx & (1<<17)) > 0 );
    // DIMM B: bit 18
    printf("  DIMM B dual rank: %u\n", (mad_dimm_chx & (1<<18)) > 0 );

    // DIMM DDR width (DBW) (0 = X8 Chips, 1 = X16 Chips)
    // DIMM A: bit 19
    printf("  DIMM A DDR width: %u\n", 8+((mad_dimm_chx & (1<<19))>>19)*8 );
    // DIMM B: bit 20
    printf("  DIMM B DDR width: %u\n", 8+((mad_dimm_chx & (1<<20))>>20)*8 );

    // Rank interleave (RI), bit 21
    printf("  Rank Interleave:  %u\n", (mad_dimm_chx & (1<<21)) > 0 );

    // Enhanced Interleave mode (Enh_Interleave), bit 22
    printf("  Enh. Interleave:  %u\n", (mad_dimm_chx & (1<<22)) > 0 );

    // ECC-Mode per Channel in Bit 25:24
    printf("  ECC in IO:        %u\n", (mad_dimm_chx & (1<<25)) > 0 );
    printf("  ECC in Logic:     %u\n", (mad_dimm_chx & (1<<24)) > 0 );

    }//decode_channel()


int main(int argc, char *argv[])
    {
    int i;
    int fd = -1;
    unsigned long pagesize;
    unsigned char *map;
    unsigned char *mem;

    fd = open("/dev/mem", O_RDONLY|O_SYNC);
    if (fd == -1) {
        perror("Error opening /dev/mem for reading");
        exit(EXIT_FAILURE);
        }

    map = mmap(0, FILESIZE, PROT_READ, MAP_SHARED, fd, MEM_START);
    if (map == MAP_FAILED) {
        close(fd);
        perror("Error mmapping the file");
        exit(EXIT_FAILURE);
        }

    // Get RAM info
    printf("5004-5007h: ");
    for (i = 0x5004; i < 0x5004+4; i++) {
        printf("%lx ", map[i]);
        }
    printf("\n");

    printf("5008-500Bh: ");
    for (i = 0x5008; i < 0x5008+4; i++) {
        printf("%lx ", map[i]);
        }
    printf("\n\n");

    printf("Interpretation:\n");
    printf("------------------\n");
    printf("Channel 0:\n");
    decode_channel(&map[0x5004]);

    printf("Channel 1:\n");
    decode_channel(&map[0x5008]);

    // Unmap the file
    if (munmap(map, FILESIZE) == -1) {
        perror("Error un-mmapping the file");
        }

    close(fd);
    return 0;
    }