linux_dsm_epyc7002/Documentation/fmc/identifiers.txt

FMC Identification
******************

The FMC standard requires every compliant mezzanine to carry
identification information in an I2C EEPROM.  The information must be
laid out according to the "IPMI Platform Management FRU Information",
where IPMI is a lie I'd better not expand, and FRU means "Field
Replaceable Unit".

The FRU information is an intricate unreadable binary blob that must
live at offset 0 of the EEPROM, and typically extends for a few hundred
bytes. The standard allows the application to use all the remaining
storage area of the EEPROM as it wants.

This chapter explains how to create your own EEPROM image and how to
write it in your mezzanine, as well as how devices and drivers are
paired at run time.  EEPROM programming uses tools that are part of this
package and SDB (part of the fpga-config-space package).

The first sections are only interesting for manufacturers who need to
write the EEPROM. If you are just a software developer writing an FMC
device or driver, you may jump straight to *note SDB Support::.


Building the FRU Structure
==========================

If you want to know the internals of the FRU structure and despair, you
can retrieve the document from
`http://download.intel.com/design/servers/ipmi/FRU1011.pdf' .  The
standard is awful and difficult without reason, so we only support the
minimum mandatory subset - we create a simple structure and parse it
back at run time, but we are not able to either generate or parse more
arcane features like non-english languages and 6-bit text.  If you need
more items of the FRU standard for your boards, please submit patches.

This package includes the Python script that Matthieu Cattin wrote to
generate the FRU binary blob, based on an helper libipmi by Manohar
Vanga and Matthieu himself.  I changed the test script to receive
parameters from the command line or from the environment (the command
line takes precedence)

To make a long story short, in order to build a standard-compliant
binary file to be burned in your EEPROM, you need the following items:

        Environment    Opt     Official Name          Default
---------------------------------------------------------------------
        FRU_VENDOR     -v      "Board Manufacturer"   fmc-example
        FRU_NAME       -n      "Board Product Name"   mezzanine
        FRU_SERIAL     -s      `Board Serial Number"  0001
        FRU_PART       -p      "Board Part Number"    sample-part
        FRU_OUTPUT     -o      not applicable         /dev/stdout

The "Official Name" above is what you find in the FRU official
documentation, chapter 11, page 7 ("Board Info Area Format").  The
output option is used to save the generated binary to a specific file
name instead of stdout.

You can pass the items to the FRU generator either in the environment
or on the command line.  This package has currently no support for
specifying power consumption or such stuff, but I plan to add it as
soon as I find some time for that.

FIXME: consumption etc for FRU are here or in PTS?

The following example creates a binary image for a specific board:

        ./tools/fru-generator -v CERN -n FmcAdc100m14b4cha \
               -s HCCFFIA___-CR000003 -p EDA-02063-V5-0 > eeprom.bin

The following example shows a script that builds several binary EEPROM
images for a series of boards, changing the serial number for each of
them. The script uses a mix of environment variables and command line
options, and uses the same string patterns shown above.

        #!/bin/sh

        export FRU_VENDOR="CERN"
        export FRU_NAME="FmcAdc100m14b4cha"
        export FRU_PART="EDA-02063-V5-0"

        serial="HCCFFIA___-CR"

        for number in $(seq 1 50); do
           # build number-string "ns"
           ns="$(printf %06d $number)"
           ./fru-generator -s "${serial}${ns}" > eeprom-${ns}.bin
        done


Using SDB-FS in the EEPROM
==========================

If you want to use SDB as a filesystem in the EEPROM device within the
mezzanine, you should create one such filesystem using gensdbfs, from
the fpga-config-space package on OHWR.

By using an SBD filesystem you can cluster several files in a single
EEPROM, so both the host system and a soft-core running in the FPGA (if
any) can access extra production-time information.

We chose to use SDB as a storage filesystem because the format is very
simple, and both the host system and the soft-core will likely already
include support code for such format. The SDB library offered by the
fpga-config-space is less than 1kB under LM32, so it proves quite up to
the task.

The SDB entry point (which acts as a directory listing) cannot live at
offset zero in the flash device, because the FRU information must live
there.  To avoid wasting precious storage space while still allowing
for more-than-minimal FRU structures, the fmc.ko will look for the SDB
record at address 256, 512 and 1024.

In order to generate the complete EEPROM image you'll need a
configuration file for gensdbfs: you tell the program where to place
the sdb entry point, and you must force the FRU data file to be placed
at the beginning of the storage device. If needed, you can also place
other files at a special offset (we sometimes do it for backward
compatibility with drivers we wrote before implementing SDB for flash
memory).

The directory tools/sdbfs of this package includes a well-commented
example that you may want to use as a starting point (the comments are
in the file called -SDB-CONFIG-).  Reading documentation for gensdbfs
is a suggested first step anyways.

This package (generic FMC bus support) only accesses two files in the
EEPROM: the FRU information, at offset zero, with a suggested filename
of IPMI-FRU and the short name for the mezzanine, in a file called
name. The IPMI-FRU name is not mandatory, but a strongly suggested
choice; the name filename is mandatory, because this is the preferred
short name used by the FMC core.  For example, a name of "fdelay" may
supplement a Product Name like "FmcDelay1ns4cha" - exactly as
demonstrated in `tools/sdbfs'.

Note: SDB access to flash memory is not yet supported, so the short
name currently in use is just the "Product Name" FRU string.

The example in tools/sdbfs includes an extra file, that is needed by
the fine-delay driver, and must live at a known address of 0x1800.  By
running gensdbfs on that directory you can output your binary EEPROM
image (here below spusa$ is the shell prompt):

        spusa$ ../fru-generator -v CERN -n FmcDelay1ns4cha -s proto-0 \
                      -p EDA-02267-V3 > IPMI-FRU
        spusa$ ls -l
        total 16
        -rw-rw-r-- 1 rubini staff 975 Nov 19 18:08 --SDB-CONFIG--
        -rw-rw-r-- 1 rubini staff 216 Nov 19 18:13 IPMI-FRU
        -rw-rw-r-- 1 rubini staff  11 Nov 19 18:04 fd-calib
        -rw-rw-r-- 1 rubini staff   7 Nov 19 18:04 name
        spusa$ sudo gensdbfs . /lib/firmware/fdelay-eeprom.bin
        spusa$ sdb-read -l -e 0x100 /lib/firmware/fdelay-eeprom.bin
        /home/rubini/wip/sdbfs/userspace/sdb-read: listing format is to be defined
        46696c6544617461:2e202020  00000100-000018ff .
        46696c6544617461:6e616d65  00000200-00000206 name
        46696c6544617461:66642d63  00001800-000018ff fd-calib
        46696c6544617461:49504d49  00000000-000000d7 IPMI-FRU
        spusa$ ../fru-dump /lib/firmware/fdelay-eeprom.bin
        /lib/firmware/fdelay-eeprom.bin: manufacturer: CERN
        /lib/firmware/fdelay-eeprom.bin: product-name: FmcDelay1ns4cha
        /lib/firmware/fdelay-eeprom.bin: serial-number: proto-0
        /lib/firmware/fdelay-eeprom.bin: part-number: EDA-02267-V3

As expected, the output file is both a proper sdbfs object and an IPMI
FRU information blob. The fd-calib file lives at offset 0x1800 and is
over-allocated to 256 bytes, according to the configuration file for
gensdbfs.