126 lines
5.9 KiB
Plaintext
126 lines
5.9 KiB
Plaintext
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fmc-write-eeprom
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================
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This module is designed to load a binary file from /lib/firmware and to
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write it to the internal EEPROM of the mezzanine card. This driver uses
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the `busid' generic parameter.
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Overwriting the EEPROM is not something you should do daily, and it is
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expected to only happen during manufacturing. For this reason, the
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module makes it unlikely for the random user to change a working EEPROM.
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The module takes the following measures:
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* It accepts a `file=' argument (within /lib/firmware) and if no
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such argument is received, it doesn't write anything to EEPROM
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(i.e. there is no default file name).
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* If the file name ends with `.bin' it is written verbatim starting
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at offset 0.
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* If the file name ends with `.tlv' it is interpreted as
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type-length-value (i.e., it allows writev(2)-like operation).
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* If the file name doesn't match any of the patterns above, it is
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ignored and no write is performed.
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* Only cards listed with `busid=' are written to. If no busid is
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specified, no programming is done (and the probe function of the
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driver will fail).
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Each TLV tuple is formatted in this way: the header is 5 bytes,
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followed by data. The first byte is `w' for write, the next two bytes
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represent the address, in little-endian byte order, and the next two
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represent the data length, in little-endian order. The length does not
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include the header (it is the actual number of bytes to be written).
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This is a real example: that writes 5 bytes at position 0x110:
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spusa.root# od -t x1 -Ax /lib/firmware/try.tlv
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000000 77 10 01 05 00 30 31 32 33 34
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00000a
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spusa.root# insmod /tmp/fmc-write-eeprom.ko busid=0x0200 file=try.tlv
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[19983.391498] spec 0000:03:00.0: write 5 bytes at 0x0110
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[19983.414615] spec 0000:03:00.0: write_eeprom: success
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Please note that you'll most likely want to use SDBFS to build your
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EEPROM image, at least if your mezzanines are being used in the White
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Rabbit environment. For this reason the TLV format is not expected to
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be used much and is not expected to be developed further.
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If you want to try reflashing fake EEPROM devices, you can use the
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fmc-fakedev.ko module (see *note fmc-fakedev::). Whenever you change
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the image starting at offset 0, it will deregister and register again
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after two seconds. Please note, however, that if fmc-write-eeprom is
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still loaded, the system will associate it to the new device, which
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will be reprogrammed and thus will be unloaded after two seconds. The
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following example removes the module after it reflashed fakedev the
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first time.
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spusa.root# insmod fmc-fakedev.ko
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[ 72.984733] fake-fmc: Manufacturer: fake-vendor
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[ 72.989434] fake-fmc: Product name: fake-design-for-testing
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spusa.root# insmod fmc-write-eeprom.ko busid=0 file=fdelay-eeprom.bin; \
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rmmod fmc-write-eeprom
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[ 130.874098] fake-fmc: Matching a generic driver (no ID)
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[ 130.887845] fake-fmc: programming 6155 bytes
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[ 130.894567] fake-fmc: write_eeprom: success
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[ 132.895794] fake-fmc: Manufacturer: CERN
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[ 132.899872] fake-fmc: Product name: FmcDelay1ns4cha
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Writing to the EEPROM
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=====================
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Once you have created a binary file for your EEPROM, you can write it
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to the storage medium using the fmc-write-eeprom (See *note
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fmc-write-eeprom::, while relying on a carrier driver. The procedure
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here shown here uses the SPEC driver
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(`http://www.ohwr.org/projects/spec-sw').
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The example assumes no driver is already loaded (actually, I unloaded
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them by hand as everything loads automatically at boot time after you
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installed the modules), and shows kernel messages together with
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commands. Here the prompt is spusa.root# and two SPEC cards are plugged
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in the system.
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spusa.root# insmod fmc.ko
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spusa.root# insmod spec.ko
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[13972.382818] spec 0000:02:00.0: probe for device 0002:0000
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[13972.392773] spec 0000:02:00.0: got file "fmc/spec-init.bin", 1484404 (0x16a674) bytes
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[13972.591388] spec 0000:02:00.0: FPGA programming successful
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[13972.883011] spec 0000:02:00.0: EEPROM has no FRU information
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[13972.888719] spec 0000:02:00.0: No device_id filled, using index
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[13972.894676] spec 0000:02:00.0: No mezzanine_name found
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[13972.899863] /home/rubini/wip/spec-sw/kernel/spec-gpio.c - spec_gpio_init
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[13972.906578] spec 0000:04:00.0: probe for device 0004:0000
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[13972.916509] spec 0000:04:00.0: got file "fmc/spec-init.bin", 1484404 (0x16a674) bytes
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[13973.115096] spec 0000:04:00.0: FPGA programming successful
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[13973.401798] spec 0000:04:00.0: EEPROM has no FRU information
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[13973.407474] spec 0000:04:00.0: No device_id filled, using index
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[13973.413417] spec 0000:04:00.0: No mezzanine_name found
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[13973.418600] /home/rubini/wip/spec-sw/kernel/spec-gpio.c - spec_gpio_init
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spusa.root# ls /sys/bus/fmc/devices
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fmc-0000 fmc-0001
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spusa.root# insmod fmc-write-eeprom.ko busid=0x0200 file=fdelay-eeprom.bin
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[14103.966259] spec 0000:02:00.0: Matching an generic driver (no ID)
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[14103.975519] spec 0000:02:00.0: programming 6155 bytes
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[14126.373762] spec 0000:02:00.0: write_eeprom: success
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[14126.378770] spec 0000:04:00.0: Matching an generic driver (no ID)
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[14126.384903] spec 0000:04:00.0: fmc_write_eeprom: no filename given: not programming
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[14126.392600] fmc_write_eeprom: probe of fmc-0001 failed with error -2
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Reading back the EEPROM
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=======================
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In order to read back the binary content of the EEPROM of your
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mezzanine device, the bus creates a read-only sysfs file called eeprom
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for each mezzanine it knows about:
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spusa.root# cd /sys/bus/fmc/devices; ls -l */eeprom
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-r--r--r-- 1 root root 8192 Apr 9 16:53 FmcDelay1ns4cha-f001/eeprom
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-r--r--r-- 1 root root 8192 Apr 9 17:19 fake-design-for-testing-f002/eeprom
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-r--r--r-- 1 root root 8192 Apr 9 17:19 fake-design-for-testing-f003/eeprom
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-r--r--r-- 1 root root 8192 Apr 9 17:19 fmc-f004/eeprom
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