Changeset 5543 for i2c-tools/trunk

Timestamp:

12/09/08 14:06:41 (3 years ago)

Author:

khali

Message:

Move checksum to a separate function. Handle CRC of FB-DIMM and DDR3
SDRAM memory modules. Based on an original patch from Paul Goyette.

Location:

i2c-tools/trunk

Files:

• CHANGES (modified) (1 diff)
• eeprom/decode-dimms (modified) (5 diffs)

i2c-tools/trunk/CHANGES

@@ -3 +3 @@
 
 SVN
+  decode-dimms: Handle CRC of FB-DIMM and DDR3 SDRAM memory modules
   i2c-stub-from-dump: Use udev settle to speed up initialization
 

i2c-tools/trunk/eeprom/decode-dimms

@@ -1222 +1222 @@
 }
 
+# Returns the (total, used) number of bytes in the EEPROM,
+# assuming it is an SPD EEPROM.
+sub spd_sizes($)
+{
+        my $bytes = shift;
+
+        if ($bytes->[2] >= 9) {
+                # For FB-DIMM and newer, decode number of bytes written
+                my $spd_len = ($bytes->[0] >> 4) & 7;
+                my $size = 64 << ($bytes->[0] & 15);
+                if ($spd_len == 0) {
+                        return ($size, 128);
+                } elsif ($spd_len == 1) {
+                        return ($size, 176);
+                } elsif ($spd_len == 2) {
+                        return ($size, 256);
+                } else {
+                        return (64, 64);
+                }
+        } else {
+                my $size;
+                if ($bytes->[1] <= 14) {
+                        $size = 1 << $bytes->[1];
+                } elsif ($bytes->[1] == 0) {
+                        $size = "RFU";
+                } else { $size = "ERROR!" }
+
+                return ($size, ($bytes->[0] < 64) ? 64 : $bytes->[0]);
+        }
+}
+
 sub readspd($$) # reads bytes from SPD-EEPROM
 {
@@ -1248 +1279 @@
 }
 
+# Calculate and verify checksum of first 63 bytes
+sub checksum($)
+{
+        my $bytes = shift;
+        my $dimm_checksum = 0;
+        local $_;
+
+        $dimm_checksum += $bytes->[$_] foreach (0 .. 62);
+        $dimm_checksum &= 0xff;
+
+        return ("EEPROM Checksum of bytes 0-62",
+                ($bytes->[63] == $dimm_checksum) ? 1 : 0,
+                sprintf('0x%02X', $bytes->[63]),
+                sprintf('0x%02X', $dimm_checksum));
+}
+
+# Calculate and verify CRC
+sub check_crc($)
+{
+        my $bytes = shift;
+        my $crc = 0;
+        my $crc_cover = $bytes->[0] & 0x80 ? 116 : 125;
+        my $crc_ptr = 0;
+        my $crc_bit;
+
+        while ($crc_ptr <= $crc_cover) {
+                $crc = $crc ^ ($bytes->[$crc_ptr] << 8);
+                for ($crc_bit = 0; $crc_bit < 8; $crc_bit++) {
+                        if ($crc & 0x8000) {
+                                $crc = ($crc << 1) ^ 0x1021;
+                        } else {
+                                $crc = $crc << 1
+                        }
+                }
+                $crc_ptr++;
+        }
+        $crc &= 0xffff;
+
+        my $dimm_crc = ($bytes->[127] << 8) | $bytes->[126];
+        return ("EEPROM CRC of bytes 0-$crc_cover",
+                ($dimm_crc == $crc) ? 1 : 0,
+                sprintf("0x%04X", $dimm_crc),
+                sprintf("0x%04X", $crc));
+}
+
 # Parse command-line
 foreach (@ARGV) {
@@ -1334 +1410 @@
          || $use_hexdump) {
                 my @bytes = readspd(128, $dimm_list[$i]);
-                my $dimm_checksum = 0;
-                $dimm_checksum += $bytes[$_] foreach (0 .. 62);
-                $dimm_checksum &= 0xff;
-
-                next unless $bytes[63] == $dimm_checksum || $opt_igncheck;
+                my ($spd_size, $spd_used) = spd_sizes(\@bytes);
+                my ($l, $chk_valid, $chk_spd, $chk_calc);
+                if ($bytes[2] < 9) {
+                        ($l, $chk_valid, $chk_spd, $chk_calc) =
+                                checksum(\@bytes);
+                } else {
+                        ($l, $chk_valid, $chk_spd, $chk_calc) =
+                                check_crc(\@bytes);
+                }
+
+                next unless $chk_valid || $opt_igncheck;
                 $dimm_count++;
 
@@ -1359 +1441 @@
                 prints "SPD EEPROM Information";
 
-                my $l = "EEPROM Checksum of bytes 0-62";
-                printl $l, ($bytes[63] == $dimm_checksum ?
-                        sprintf("OK (0x%.2X)", $bytes[63]):
-                        sprintf("Bad\n(found 0x%.2X, calculated 0x%.2X)\n",
-                                $bytes[63], $dimm_checksum));
+                printl $l, ($chk_valid ?
+                        sprintf("OK (%s)", $chk_calc) :
+                        sprintf("Bad\n(found %s, calculated %s)\n",
+                                $chk_spd, $chk_calc));
 
                 # Simple heuristic to detect Rambus
@@ -1375 +1456 @@
                         printl "SPD Revision", $temp;
                 } else {
-                        printl "# of bytes written to SDRAM EEPROM",
-                               $bytes[0];
+                        printl "# of bytes written to SDRAM EEPROM", $spd_used;
                 }
 
                 $l = "Total number of bytes in EEPROM";
-                if ($bytes[1] <= 14) {
-                        printl $l, 2**$bytes[1];
-                } elsif ($bytes[1] == 0) {
-                        printl $l, "RFU";
-                } else { printl $l, "ERROR!"; }
+                printl $l, $spd_size;
 
                 $l = "Fundamental Memory type";
-                my $type = "Unknown";
+                my $type = sprintf("Unknown (0x%02x)", $bytes[2]);
                 if ($is_rambus) {
                         if ($bytes[2] == 1) { $type = "Direct Rambus"; }
                         elsif ($bytes[2] == 17) { $type = "Rambus"; }
                 } else {
-                        if ($bytes[2] == 1) { $type = "FPM DRAM"; }
-                        elsif ($bytes[2] == 2) { $type = "EDO"; }
-                        elsif ($bytes[2] == 3) { $type = "Pipelined Nibble"; }
-                        elsif ($bytes[2] == 4) { $type = "SDR SDRAM"; }
-                        elsif ($bytes[2] == 5) { $type = "Multiplexed ROM"; }
-                        elsif ($bytes[2] == 6) { $type = "DDR SGRAM"; }
-                        elsif ($bytes[2] == 7) { $type = "DDR SDRAM"; }
-                        elsif ($bytes[2] == 8) { $type = "DDR2 SDRAM"; }
+                        my @type_list = (
+                                "Reserved", "FPM DRAM",         # 0, 1
+                                "EDO", "Pipelined Nibble",      # 2, 3
+                                "SDR SDRAM", "Multiplexed ROM", # 4, 5
+                                "DDR SGRAM", "DDR SDRAM",       # 6, 7
+                                "DDR2 SDRAM", "FB-DIMM",        # 8, 9
+                                "FB-DIMM Probe", "DDR3 SDRAM",  # 10, 11
+                        );
+                        if ($bytes[2] < @type_list) {
+                                $type = $type_list[$bytes[2]];
+                        }
                 }
                 printl $l, $type;