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Documentation / fmc / fmc-write-eeprom.txt




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Based on kernel version 3.13. Page generated on 2014-01-20 22:03 EST.

1	fmc-write-eeprom
2	================
3	
4	This module is designed to load a binary file from /lib/firmware and to
5	write it to the internal EEPROM of the mezzanine card. This driver uses
6	the `busid' generic parameter.
7	
8	Overwriting the EEPROM is not something you should do daily, and it is
9	expected to only happen during manufacturing. For this reason, the
10	module makes it unlikely for the random user to change a working EEPROM.
11	
12	The module takes the following measures:
13	
14	   * It accepts a `file=' argument (within /lib/firmware) and if no
15	     such argument is received, it doesn't write anything to EEPROM
16	     (i.e. there is no default file name).
17	
18	   * If the file name ends with `.bin' it is written verbatim starting
19	     at offset 0.
20	
21	   * If the file name ends with `.tlv' it is interpreted as
22	     type-length-value (i.e., it allows writev(2)-like operation).
23	
24	   * If the file name doesn't match any of the patterns above, it is
25	     ignored and no write is performed.
26	
27	   * Only cards listed with `busid=' are written to. If no busid is
28	     specified, no programming is done (and the probe function of the
29	     driver will fail).
30	
31	
32	Each TLV tuple is formatted in this way: the header is 5 bytes,
33	followed by data. The first byte is `w' for write, the next two bytes
34	represent the address, in little-endian byte order, and the next two
35	represent the data length, in little-endian order. The length does not
36	include the header (it is the actual number of bytes to be written).
37	
38	This is a real example: that writes 5 bytes at position 0x110:
39	
40	        spusa.root# od -t x1 -Ax /lib/firmware/try.tlv
41	        000000 77 10 01 05 00 30 31 32 33 34
42	        00000a
43	        spusa.root# insmod /tmp/fmc-write-eeprom.ko busid=0x0200 file=try.tlv
44	        [19983.391498] spec 0000:03:00.0: write 5 bytes at 0x0110
45	        [19983.414615] spec 0000:03:00.0: write_eeprom: success
46	
47	Please note that you'll most likely want to use SDBFS to build your
48	EEPROM image, at least if your mezzanines are being used in the White
49	Rabbit environment. For this reason the TLV format is not expected to
50	be used much and is not expected to be developed further.
51	
52	If you want to try reflashing fake EEPROM devices, you can use the
53	fmc-fakedev.ko module (see *note fmc-fakedev::).  Whenever you change
54	the image starting at offset 0, it will deregister and register again
55	after two seconds.  Please note, however, that if fmc-write-eeprom is
56	still loaded, the system will associate it to the new device, which
57	will be reprogrammed and thus will be unloaded after two seconds.  The
58	following example removes the module after it reflashed fakedev the
59	first time.
60	
61	     spusa.root# insmod fmc-fakedev.ko
62	        [   72.984733]  fake-fmc: Manufacturer: fake-vendor
63	        [   72.989434]  fake-fmc: Product name: fake-design-for-testing
64	        spusa.root# insmod fmc-write-eeprom.ko busid=0 file=fdelay-eeprom.bin; \
65	            rmmod fmc-write-eeprom
66	        [  130.874098]  fake-fmc: Matching a generic driver (no ID)
67	        [  130.887845]  fake-fmc: programming 6155 bytes
68	        [  130.894567]  fake-fmc: write_eeprom: success
69	        [  132.895794]  fake-fmc: Manufacturer: CERN
70	        [  132.899872]  fake-fmc: Product name: FmcDelay1ns4cha
71	
72	
73	Writing to the EEPROM
74	=====================
75	
76	Once you have created a binary file for your EEPROM, you can write it
77	to the storage medium using the fmc-write-eeprom (See *note
78	fmc-write-eeprom::, while relying on a carrier driver.  The procedure
79	here shown here uses the SPEC driver
80	(`http://www.ohwr.org/projects/spec-sw').
81	
82	The example assumes no driver is already loaded (actually, I unloaded
83	them by hand as everything loads automatically at boot time after you
84	installed the modules), and shows kernel messages together with
85	commands. Here the prompt is spusa.root# and two SPEC cards are plugged
86	in the system.
87	
88	     spusa.root# insmod fmc.ko
89	     spusa.root# insmod spec.ko
90	     [13972.382818] spec 0000:02:00.0:  probe for device 0002:0000
91	     [13972.392773] spec 0000:02:00.0: got file "fmc/spec-init.bin", 1484404 (0x16a674) bytes
92	     [13972.591388] spec 0000:02:00.0: FPGA programming successful
93	     [13972.883011] spec 0000:02:00.0: EEPROM has no FRU information
94	     [13972.888719] spec 0000:02:00.0: No device_id filled, using index
95	     [13972.894676] spec 0000:02:00.0: No mezzanine_name found
96	     [13972.899863] /home/rubini/wip/spec-sw/kernel/spec-gpio.c - spec_gpio_init
97	     [13972.906578] spec 0000:04:00.0:  probe for device 0004:0000
98	     [13972.916509] spec 0000:04:00.0: got file "fmc/spec-init.bin", 1484404 (0x16a674) bytes
99	     [13973.115096] spec 0000:04:00.0: FPGA programming successful
100	     [13973.401798] spec 0000:04:00.0: EEPROM has no FRU information
101	     [13973.407474] spec 0000:04:00.0: No device_id filled, using index
102	     [13973.413417] spec 0000:04:00.0: No mezzanine_name found
103	     [13973.418600] /home/rubini/wip/spec-sw/kernel/spec-gpio.c - spec_gpio_init
104	     spusa.root# ls /sys/bus/fmc/devices
105	     fmc-0000  fmc-0001
106	     spusa.root# insmod fmc-write-eeprom.ko busid=0x0200 file=fdelay-eeprom.bin
107	     [14103.966259] spec 0000:02:00.0: Matching an generic driver (no ID)
108	     [14103.975519] spec 0000:02:00.0: programming 6155 bytes
109	     [14126.373762] spec 0000:02:00.0: write_eeprom: success
110	     [14126.378770] spec 0000:04:00.0: Matching an generic driver (no ID)
111	     [14126.384903] spec 0000:04:00.0: fmc_write_eeprom: no filename given: not programming
112	     [14126.392600] fmc_write_eeprom: probe of fmc-0001 failed with error -2
113	
114	Reading back the EEPROM
115	=======================
116	
117	In order to read back the binary content of the EEPROM of your
118	mezzanine device, the bus creates a read-only sysfs file called eeprom
119	for each mezzanine it knows about:
120	
121	   spusa.root# cd /sys/bus/fmc/devices; ls -l */eeprom
122	   -r--r--r-- 1 root root 8192 Apr  9 16:53 FmcDelay1ns4cha-f001/eeprom
123	   -r--r--r-- 1 root root 8192 Apr  9 17:19 fake-design-for-testing-f002/eeprom
124	   -r--r--r-- 1 root root 8192 Apr  9 17:19 fake-design-for-testing-f003/eeprom
125	   -r--r--r-- 1 root root 8192 Apr  9 17:19 fmc-f004/eeprom
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