| 1 | Kernel driver `eeprom.o' |
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| 2 | ======================== |
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| 3 | |
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| 4 | Status: Complete and well-tested |
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| 5 | |
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| 6 | Supported chips: |
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| 7 | * Any EEPROM chip in the designated address range |
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| 8 | Prefix `eeprom' |
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| 9 | Addresses scanned: I2C 0x50 - 0x57 (inclusive) |
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| 10 | Datasheet: Publicly available from Intel |
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| 11 | |
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| 12 | Author: Frodo Looijaard <frodol@dds.nl> and Philip Edelbrock |
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| 13 | <phil@netroedge.com> |
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| 14 | |
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| 15 | |
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| 16 | Module Parameters |
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| 17 | ----------------- |
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| 18 | |
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| 19 | * checksum: int |
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| 20 | Only accept eeproms whose checksum is correct |
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| 21 | * force: short array (min = 1, max = 48) |
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| 22 | List of adapter,address pairs to boldly assume to be present |
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| 23 | * force_eeprom: short array (min = 1, max = 48) |
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| 24 | List of adapter,address pairs which are unquestionably assumed to contain |
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| 25 | a `eeprom' chip |
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| 26 | * ignore: short array (min = 1, max = 48) |
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| 27 | List of adapter,address pairs not to scan |
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| 28 | * ignore_range: short array (min = 1, max = 48) |
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| 29 | List of adapter,start-addr,end-addr triples not to scan |
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| 30 | * probe: short array (min = 1, max = 48) |
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| 31 | List of adapter,address pairs to scan additionally |
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| 32 | * probe_range: short array (min = 1, max = 48) |
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| 33 | List of adapter,start-addr,end-addr triples to scan additionally |
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| 34 | |
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| 35 | |
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| 36 | Description |
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| 37 | ----------- |
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| 38 | |
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| 39 | This is a simple EEPROM module meant to enable reading the first 128 bytes |
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| 40 | of an EEPROM (on a SDRAM DIMM). This module will probably need to be at |
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| 41 | least expanded. A /dev file interface would probably be more effective. |
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| 42 | This module was a programming exercise to get used to the new project |
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| 43 | organization laid out by Frodo, but it should be at least completely |
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| 44 | effective for decoding the contents of EEPROMs on DIMMs. |
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| 45 | |
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| 46 | Lacking functionality: |
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| 47 | |
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| 48 | * Read past byte 128. There is no technical restriction for not doing |
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| 49 | this, but making a zillion dataxx-xx files would be a bit rediculous. |
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| 50 | EEPROMs on DIMMs shouldn't use the contents past byte 128, so we are fine. |
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| 51 | |
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| 52 | * Enable Writing. Again, no technical reason why not, but making it easy |
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| 53 | to change the contents of the EEPROMs (on DIMMs anyway) also makes it easy |
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| 54 | to disable the DIMMs until the values are restored somehow. |
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| 55 | |
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| 56 | Use: |
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| 57 | |
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| 58 | After inserting the module (and any other required smbus/i2c modules), you |
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| 59 | should have some EEPROM directories in /proc/sys/dev/sensors/ of names such |
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| 60 | as "eeprom-i2c-0-50". Inside each of these is a series of files which |
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| 61 | represent 16 bytes blocks from the EEPROM. The data is in decimal (base |
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| 62 | 10) delimited by spaces. |
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| 63 | |
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| 64 | Note: |
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| 65 | |
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| 66 | EEPROMs reported are not nessesarily all from DIMMs. Xeon processors, for |
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| 67 | example, have serial EEPROMs in them connected to the SMBus which will be |
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| 68 | found by the module. Take care to ignore the output of decode_dimms.pl for |
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| 69 | these EEPROMs. |
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| 70 | |
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| 71 | |
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| 72 | DECODE_DIMMS.PL |
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| 73 | --------------- |
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| 74 | |
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| 75 | This Perl script attempts to make sense of the first 128 bytes of a SDRAM |
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| 76 | PC-100 DIMM. Using the 'Serial Presence Detect (SPD)' Spec (Rev1.2a)** from |
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| 77 | Intel. When finished, it will decode and report all the values defined in |
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| 78 | the spec. Much of the information is technical timing and interfacing info |
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| 79 | (probably not all used by the Bios or clocking IC. |
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| 80 | |
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| 81 | Note: During testing, we noticed that many DIMMs have trucated SPD records. |
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| 82 | I'm not sure if these conform to an old spec, or if the manufacturers are |
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| 83 | simply just taking short-cuts. But, many DIMMs have all zeros stored past |
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| 84 | byte 21. I asked an Intel SDRAM tester, Sat Kolli (skolli@smartm.com), |
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| 85 | about this and this is what he had to say: |
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| 86 | |
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| 87 | "[...] Now in terms of SPD contents, you are right that people do all kinds |
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| 88 | of things. The way to insure that any module works is to look for the most |
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| 89 | basic information, such as module bank density, number of banks, and device |
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| 90 | addresses. That will give you the module size and what devices are used. It |
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| 91 | is very difficult to verify if the module is PC-100, because of |
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| 92 | inconsistencies between spd data from different manufacturers. You could |
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| 93 | read the timing information or the special Intel bytes (126 & 127) but I do |
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| 94 | not know how many program that information.These inconsistencies may be |
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| 95 | minimized if you or your customers stay with some of the better known |
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| 96 | manufacturers." (Thanks goes to Sat Kolli for his comments and help) |
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| 97 | |
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| 98 | Use: |
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| 99 | |
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| 100 | After inserting the nessesary modules, run the script! |
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| 101 | |
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| 102 | Notes: |
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| 103 | |
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| 104 | The script assumes that Perl can be found at /usr/bin/perl. If different, |
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| 105 | you will need to adjust the first line of the file accordingly, or else |
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| 106 | you will get a strange "decode_dimms.pl: no such file or directory" error. |
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| 107 | |
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| 108 | Also note that the script assumes that _all_ the eeproms belong to DIMMs, |
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| 109 | which may not be the case. |
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