support detection of eeprom shadows we now know are

software write-protect registers.
      prevent Vaio detection from running more than once.
      update eeprom driver documentation.


git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@2448 7894878c-1315-0410-8ee3-d5d059ff63e0

CHANGES

@@ -45,6 +45,7 @@ ask CVS about it:
                           Explicitely support ADM1028
                           Scan all logical devices of PC87365 and PC87366
                           Detect LM92, LM76, MAX6633, MAX6634, MAX6635
+                          Detect eeproms with software write protect
 
 
 2.8.6 (20040405)

doc/chips/eeprom

@@ -7,9 +7,15 @@ Supported chips:
   * Any EEPROM chip in the designated address range
     Prefix `eeprom'
     Addresses scanned: I2C 0x50 - 0x57 (inclusive)
-    Datasheets: Publicly available from Atmel (www.atmel.com),
+    Datasheets: Publicly available from:
-                Fairchild (www.fairchildsemi.com), and
+                Atmel (www.atmel.com),
-                Microchip (www.microchip.com)
+                Catalyst (www.catsemi.com),
+                Fairchild (www.fairchildsemi.com),
+                Microchip (www.microchip.com),
+                Philips (www.semiconductor.philips.com),
+                Rohm (www.rohm.com),
+                ST (www.st.com),	
+                Xicor (www.xicor.com)		
 
         Chip     Size (bits)    Address
         24C01     1K            0x50 (shadows at 0x51 - 0x57)
@@ -21,6 +27,8 @@ Supported chips:
                                 0x53, 0x55, 0x56, 0x57)
         24C16    16K            0x50 (additional data at 0x51 - 0x57)
 	Sony      2K            0x57
+        Microchip 24AA52  2K    0x50 - 0x57, SW write protect at 0x30-37
+        ST M34C02         2K    0x50 - 0x57, SW write protect at 0x30-37
 
 
 Author: Frodo Looijaard <frodol@dds.nl> and Philip Edelbrock
@@ -72,6 +80,15 @@ eeprom.
 Recent Sony Vaio laptops have an EEPROM at 0x57. We couldn't get the
 specification, so it is guess work and far from being complete.
 
+The Microchip 24AA52/24LCS52 and the ST M34C02 support an additional
+software write protect register at 0x30 - 0x37 (0x20 less than the
+memory location). The chip responds to "write quick" detection at this
+address but does not respond to byte reads.
+If this register is present, the lower 128 bytes of the memory
+array are not write protected. Any byte data write to this address
+will write protect the memory array permanently, and the device
+will no longer respond at the 0x30-37 address.
+The eeprom driver does not support this register.
 
 Lacking functionality:
 
@@ -84,7 +101,8 @@ These devices require two-byte address fields and are not supported.
 
 * Enable Writing.  Again, no technical reason why not, but making it easy
 to change the contents of the EEPROMs (on DIMMs anyway) also makes it easy
-to disable the DIMMs until the values are restored somehow.
+to disable the DIMMs (potentially preventing the computer from booting)
+until the values are restored somehow.
 
 
 Use:

prog/detect/sensors-detect

@@ -1245,6 +1245,12 @@ use subs qw(mtp008_detect lm78_detect lm78_isa_detect lm78_alias_detect
        i2c_addrs => [0x57],
        i2c_detect => sub { eeprom_detect 1, @_ },
      },
+     {
+       name => "SPD EEPROM with Software Write-Protect",
+       driver => "eeprom",
+       i2c_addrs => [0x50..0x57],
+       i2c_detect => sub { eeprom_detect 2, @_ },
+     },
      {
        name => "LTC1710",
        driver => "ltc1710",
@@ -3672,7 +3678,8 @@ sub ite_alias_detect
   return 1;
 }
 
-# $_[0]: Chip to detect (0 = SPD EEPROM, 1 = Sony Vaio EEPROM)
+# $_[0]: Chip to detect (0 = SPD EEPROM, 1 = Sony Vaio EEPROM
+#                        2 = SPD EEPROM with Software Write Protect)
 # $_[1]: A reference to the file descriptor to access this chip
 # $_[2]: Address
 # Returns: 8 for a memory eeprom, 4 to 9 for a Sony Vaio eeprom,
@@ -3687,17 +3694,37 @@ sub ite_alias_detect
 sub eeprom_detect
 {
   my ($chip,$file,$addr) = @_;
+  my $checksum = 0;
 
   # Check the checksum for validity (works for most DIMMs and RIMMs)
-  my $checksum = 0;
+  if ($chip != 1) {
 	  for (my $i = 0; $i <= 62; $i ++) {
 	    $checksum += i2c_smbus_read_byte_data($file,$i);
 	  }
 	  $checksum &= 255;
-  return 8
+	  $checksum -= i2c_smbus_read_byte_data($file,63);
-    if $chip == 0 and i2c_smbus_read_byte_data($file,63) == $checksum;
+  }     
+  if ($chip == 0) {
+	if($checksum == 0) {
+		return 8;
+	} else {
+		return 1;
+	}
+  }	
+  if ($chip == 2) {
+	# check for 'shadow' write-protect register at 0x30-37
+	i2c_set_slave_addr($file,$addr - 0x20);
+	if(i2c_smbus_write_quick($file,$SMBUS_WRITE) >= 0 &&
+	   i2c_smbus_read_byte_data($file,0x80) == -1) {
+		if($checksum == 0) {
+			return (9, $addr - 0x20);
+		} else {
+			return (2, $addr - 0x20);
+		}
+	}
+  }
 
-  # Look for a Sony Vaio EEPROM
+  # Look for a Sony Vaio EEPROM ($chip == 1)
   my $vaioconf = 1;
   $vaioconf += 4
     if i2c_smbus_read_byte_data($file,0x80) == 0x50
@@ -3718,14 +3745,9 @@ sub eeprom_detect
     if $vaioconf > 9;
 
   if ($vaioconf > 1) {
-    return if $chip != 1;
     return $vaioconf;
   }
-
+  return;
-  # Even if all tests fail, it still may be an eeprom
-  return if $chip != 0;
-  # Default to SPD EEPROM
-  return 1;
 }
 
 # $_[0]: A reference to the file descriptor to access this chip.