FMC: make eeprom attribute writable
This allows easier modification to the eeprom than loading the
fmc-write-eeprom module. The carrier driver will refuse writing if
the FPGA is not running the golden gateware image, so writing in
practice is only available at manufacture/development time.
Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
Acked-by: Juan David Gonzalez Cobas <dcobas@cern.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/Documentation/fmc/fmc-write-eeprom.txt b/Documentation/fmc/fmc-write-eeprom.txt
index 44a3bc6..e0a9712 100644
--- a/Documentation/fmc/fmc-write-eeprom.txt
+++ b/Documentation/fmc/fmc-write-eeprom.txt
@@ -9,7 +9,12 @@
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:
+However, since the EEPROM may include application-specific information
+other than the identification, later versions of this packages added
+write-support through sysfs. See *note Accessing the EEPROM::.
+
+To avoid damaging the EEPROM content, 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
@@ -70,56 +75,24 @@
[ 132.899872] fake-fmc: Product name: FmcDelay1ns4cha
-Writing to the EEPROM
+Accessing 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 bus creates a sysfs binary file called eeprom for each mezzanine it
+knows about:
-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# cd /sys/bus/fmc/devices; ls -l */eeprom
+ -r--r--r-- 1 root root 8192 Feb 21 12:30 FmcAdc100m14b4cha-0800/eeprom
+ -r--r--r-- 1 root root 8192 Feb 21 12:30 FmcDelay1ns4cha-0200/eeprom
+ -r--r--r-- 1 root root 8192 Feb 21 12:30 FmcDio5cha-0400/eeprom
- 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
+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 I2C bus. For example, the spec driver can access the bus
+only with its golden gateware: after a mezzanine driver reprogrammed
+the FPGA with a custom circuit, the carrier is unable to access the
+EEPROM and returns ENOTSUPP.
-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
+An alternative way to write the EEPROM is the mezzanine driver
+fmc-write-eeprom (See *note fmc-write-eeprom::), but the procedure is
+more complex.
diff --git a/drivers/fmc/fmc-core.c b/drivers/fmc/fmc-core.c
index 5a5e616..353fc54 100644
--- a/drivers/fmc/fmc-core.c
+++ b/drivers/fmc/fmc-core.c
@@ -99,10 +99,23 @@
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 = {
- .attr = { .name = "eeprom", .mode = S_IRUGO, },
+ .attr = { .name = "eeprom", .mode = S_IRUGO | S_IWUSR, },
.size = 8192, /* more or less standard */
.read = fmc_read_eeprom,
+ .write = fmc_write_eeprom,
};
/*