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FMC Bus
Commit 20a4f017 authored by Alessandro Rubini's avatar Alessandro Rubini
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FMC: make eeprom attribute writable 

This allows easier modification to the eeprom than loading the
fmc-write-eeprom module.  The carrier driver will likely refuse
writing if the FPGA is not running the golden gateware image.
Signed-off-by: Alessandro Rubini's avatarAlessandro Rubini <rubini@gnudd.com>
parent 2f0cb305
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doc/fmc-bus.in
View file @ 20a4f017
...@@ -34,7 +34,7 @@ ...@@ -34,7 +34,7 @@
@setchapternewpage off @setchapternewpage off
@set update-month May 2013 @set update-month February 2014
@finalout @finalout
...@@ -868,7 +868,12 @@ Overwriting the @sc{eeprom} is not something you should do daily, and it is ...@@ -868,7 +868,12 @@ Overwriting the @sc{eeprom} is not something you should do daily, and it is
expected to only happen during manufacturing. For this reason, the expected to only happen during manufacturing. For this reason, the
module makes it unlikely for the random user to change a working @sc{eeprom}. module makes it unlikely for the random user to change a working @sc{eeprom}.
The module takes the following measures: However, since the @sc{eeprom} ma include application-specific information
other than the identification, later versions of this packages added
write-support through @i{sysfs}. See @ref{Accessing the EEPROM}.
To avoid damaging the @sc{eeprom} content, the module takes the
following measures:
@itemize @bullet @itemize @bullet
...@@ -1621,65 +1626,32 @@ offset 0x1800 and is over-allocated to 256 bytes, according to the ...@@ -1621,65 +1626,32 @@ offset 0x1800 and is over-allocated to 256 bytes, according to the
configuration file for @i{gensdbfs}. configuration file for @i{gensdbfs}.
@c ========================================================================== @c ==========================================================================
@node Writing to the EEPROM @node Accessing the EEPROM
@section Writing to the EEPROM @section Accessing the EEPROM
Once you have created a binary file for your @sc{eeprom}, you can
write it to the storage medium using the @t{fmc-write-eeprom} (See
@ref{fmc-write-eeprom}, while relying on a carrier driver. The
procedure here shown here uses the @sc{spec} driver
(@url{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 @t{spusa.root#} and two @sc{spec} cards
are plugged in the system.
@smallexample The bus creates a read-only @i{sysfs} file called
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
@end smallexample
@c ==========================================================================
@node Reading back the EEPROM
@section Reading back the EEPROM
In order to read back the binary content of the @sc{eeprom} of your
mezzanine device, the bus creates a read-only @i{sysfs} file called
@t{eeprom} for each mezzanine it knows about: @t{eeprom} for each mezzanine it knows about:
@smallexample @smallexample
spusa.root# cd /sys/bus/fmc/devices; ls -l */eeprom spusa.root# cd /sys/bus/fmc/devices; ls -l */eeprom
-r--r--r-- 1 root root 8192 Apr 9 16:53 FmcDelay1ns4cha-f001/eeprom -rw-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 -rw-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 -rw-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 -rw-r--r-- 1 root root 8192 Apr 9 17:19 fmc-f004/eeprom
@end smallexample @end smallexample
Everybody can read the files and the superuser can also modify it,
but the operation may on the carrier driver, if the carrier
is unable to access the @sc{i2c} bus. For example, the @i{spec}
driver can access the bus only with its @i{golden} gateware: after
a mezzanine driver reprogrammed the @sc{fpga} with a custom circuit,
the carrier is unable to access the @sc{eeprom} and returns
@t{ENOTSUPP}.
An alternative way to write the @sc{eeprom} is the mezzanine
driver @t{fmc-write-eeprom} (See @ref{fmc-write-eeprom}), but
the procedure is more complex.
@c ========================================================================== @c ==========================================================================
@c @node How Identification Works at Run Time @c @node How Identification Works at Run Time
@c @section How Identification Works at Run Time @c @section How Identification Works at Run Time
......
kernel/fmc-core.c
View file @ 20a4f017
...@@ -99,10 +99,23 @@ static ssize_t fmc_read_eeprom(struct file *file, struct kobject *kobj, ...@@ -99,10 +99,23 @@ static ssize_t fmc_read_eeprom(struct file *file, struct kobject *kobj,
return count; return count;
} }
static ssize_t fmc_write_eeprom(struct file *file, struct kobject *kobj,
struct bin_attribute *bin_attr,
char *buf, loff_t off, size_t count)
{
struct device *dev;
struct fmc_device *fmc;
dev = container_of(kobj, struct device, kobj);
fmc = container_of(dev, struct fmc_device, dev);
return fmc->op->write_ee(fmc, off, buf, count);
}
static struct bin_attribute fmc_eeprom_attr = { static struct bin_attribute fmc_eeprom_attr = {
.attr = { .name = "eeprom", .mode = S_IRUGO, }, .attr = { .name = "eeprom", .mode = S_IRUGO | S_IWUSR, },
.size = 8192, /* more or less standard */ .size = 8192, /* more or less standard */
.read = fmc_read_eeprom, .read = fmc_read_eeprom,
.write = fmc_write_eeprom,
}; };
/* /*
......
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