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Diffstat (limited to 'Documentation/fmc/fmc-write-eeprom.txt')
| -rw-r--r-- | Documentation/fmc/fmc-write-eeprom.txt | 125 |
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diff --git a/Documentation/fmc/fmc-write-eeprom.txt b/Documentation/fmc/fmc-write-eeprom.txt new file mode 100644 index 000000000000..44a3bc678bf0 --- /dev/null +++ b/Documentation/fmc/fmc-write-eeprom.txt @@ -0,0 +1,125 @@ +fmc-write-eeprom +================ + +This module is designed to load a binary file from /lib/firmware and to +write it to the internal EEPROM of the mezzanine card. This driver uses +the `busid' generic parameter. + +Overwriting the EEPROM is not something you should do daily, and it is +expected to only happen during manufacturing. For this reason, the +module makes it unlikely for the random user to change a working EEPROM. + +The module takes the following measures: + + * It accepts a `file=' argument (within /lib/firmware) and if no + such argument is received, it doesn't write anything to EEPROM + (i.e. there is no default file name). + + * If the file name ends with `.bin' it is written verbatim starting + at offset 0. + + * If the file name ends with `.tlv' it is interpreted as + type-length-value (i.e., it allows writev(2)-like operation). + + * If the file name doesn't match any of the patterns above, it is + ignored and no write is performed. + + * Only cards listed with `busid=' are written to. If no busid is + specified, no programming is done (and the probe function of the + driver will fail). + + +Each TLV tuple is formatted in this way: the header is 5 bytes, +followed by data. The first byte is `w' for write, the next two bytes +represent the address, in little-endian byte order, and the next two +represent the data length, in little-endian order. The length does not +include the header (it is the actual number of bytes to be written). + +This is a real example: that writes 5 bytes at position 0x110: + + spusa.root# od -t x1 -Ax /lib/firmware/try.tlv + 000000 77 10 01 05 00 30 31 32 33 34 + 00000a + spusa.root# insmod /tmp/fmc-write-eeprom.ko busid=0x0200 file=try.tlv + [19983.391498] spec 0000:03:00.0: write 5 bytes at 0x0110 + [19983.414615] spec 0000:03:00.0: write_eeprom: success + +Please note that you'll most likely want to use SDBFS to build your +EEPROM image, at least if your mezzanines are being used in the White +Rabbit environment. For this reason the TLV format is not expected to +be used much and is not expected to be developed further. + +If you want to try reflashing fake EEPROM devices, you can use the +fmc-fakedev.ko module (see *note fmc-fakedev::). Whenever you change +the image starting at offset 0, it will deregister and register again +after two seconds. Please note, however, that if fmc-write-eeprom is +still loaded, the system will associate it to the new device, which +will be reprogrammed and thus will be unloaded after two seconds. The +following example removes the module after it reflashed fakedev the +first time. + + spusa.root# insmod fmc-fakedev.ko + [ 72.984733] fake-fmc: Manufacturer: fake-vendor + [ 72.989434] fake-fmc: Product name: fake-design-for-testing + spusa.root# insmod fmc-write-eeprom.ko busid=0 file=fdelay-eeprom.bin; \ + rmmod fmc-write-eeprom + [ 130.874098] fake-fmc: Matching a generic driver (no ID) + [ 130.887845] fake-fmc: programming 6155 bytes + [ 130.894567] fake-fmc: write_eeprom: success + [ 132.895794] fake-fmc: Manufacturer: CERN + [ 132.899872] fake-fmc: Product name: FmcDelay1ns4cha + + +Writing to the EEPROM +===================== + +Once you have created a binary file for your EEPROM, you can write it +to the storage medium using the fmc-write-eeprom (See *note +fmc-write-eeprom::, while relying on a carrier driver. The procedure +here shown here uses the SPEC driver +(`http://www.ohwr.org/projects/spec-sw'). + +The example assumes no driver is already loaded (actually, I unloaded +them by hand as everything loads automatically at boot time after you +installed the modules), and shows kernel messages together with +commands. Here the prompt is spusa.root# and two SPEC cards are plugged +in the system. + + spusa.root# insmod fmc.ko + spusa.root# insmod spec.ko + [13972.382818] spec 0000:02:00.0: probe for device 0002:0000 + [13972.392773] spec 0000:02:00.0: got file "fmc/spec-init.bin", 1484404 (0x16a674) bytes + [13972.591388] spec 0000:02:00.0: FPGA programming successful + [13972.883011] spec 0000:02:00.0: EEPROM has no FRU information + [13972.888719] spec 0000:02:00.0: No device_id filled, using index + [13972.894676] spec 0000:02:00.0: No mezzanine_name found + [13972.899863] /home/rubini/wip/spec-sw/kernel/spec-gpio.c - spec_gpio_init + [13972.906578] spec 0000:04:00.0: probe for device 0004:0000 + [13972.916509] spec 0000:04:00.0: got file "fmc/spec-init.bin", 1484404 (0x16a674) bytes + [13973.115096] spec 0000:04:00.0: FPGA programming successful + [13973.401798] spec 0000:04:00.0: EEPROM has no FRU information + [13973.407474] spec 0000:04:00.0: No device_id filled, using index + [13973.413417] spec 0000:04:00.0: No mezzanine_name found + [13973.418600] /home/rubini/wip/spec-sw/kernel/spec-gpio.c - spec_gpio_init + spusa.root# ls /sys/bus/fmc/devices + fmc-0000 fmc-0001 + spusa.root# insmod fmc-write-eeprom.ko busid=0x0200 file=fdelay-eeprom.bin + [14103.966259] spec 0000:02:00.0: Matching an generic driver (no ID) + [14103.975519] spec 0000:02:00.0: programming 6155 bytes + [14126.373762] spec 0000:02:00.0: write_eeprom: success + [14126.378770] spec 0000:04:00.0: Matching an generic driver (no ID) + [14126.384903] spec 0000:04:00.0: fmc_write_eeprom: no filename given: not programming + [14126.392600] fmc_write_eeprom: probe of fmc-0001 failed with error -2 + +Reading back the EEPROM +======================= + +In order to read back the binary content of the EEPROM of your +mezzanine device, the bus creates a read-only sysfs file called eeprom +for each mezzanine it knows about: + + spusa.root# cd /sys/bus/fmc/devices; ls -l */eeprom + -r--r--r-- 1 root root 8192 Apr 9 16:53 FmcDelay1ns4cha-f001/eeprom + -r--r--r-- 1 root root 8192 Apr 9 17:19 fake-design-for-testing-f002/eeprom + -r--r--r-- 1 root root 8192 Apr 9 17:19 fake-design-for-testing-f003/eeprom + -r--r--r-- 1 root root 8192 Apr 9 17:19 fmc-f004/eeprom |