Commit 4debfe40 authored by Alessandro Rubini's avatar Alessandro Rubini Committed by Greg Kroah-Hartman

FMC: add a char-device mezzanine driver

This driver exports the memory area associated with the mezzanine card
as a misc device, so users can access registers.
Signed-off-by: 's avatarAlessandro Rubini <rubini@gnudd.com>
Acked-by: 's avatarJuan David Gonzalez Cobas <dcobas@cern.ch>
Acked-by: 's avatarEmilio G. Cota <cota@braap.org>
Acked-by: 's avatarSamuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6007b1bd
......@@ -32,4 +32,7 @@ fmc-trivial.txt
- about drivers/fmc/fmc-trivial.ko
fmc-write-eeprom.txt
- about drivers/fmc/fmc-write-eeprom.ko
- about drivers/fmc/fmc-write-eeprom.ko
fmc-chardev.txt
- about drivers/fmc/fmc-chardev.ko
fmc-chardev
===========
This is a simple generic driver, that allows user access by means of a
character device (actually, one for each mezzanine it takes hold of).
The char device is created as a misc device. Its name in /dev (as
created by udev) is the same name as the underlying FMC device. Thus,
the name can be a silly fmc-0000 look-alike if the device has no
identifiers nor bus_id, a more specific fmc-0400 if the device has a
bus-specific address but no associated name, or something like
fdelay-0400 if the FMC core can rely on both a mezzanine name and a bus
address.
Currently the driver only supports read and write: you can lseek to the
desired address and read or write a register.
The driver assumes all registers are 32-bit in size, and only accepts a
single read or write per system call. However, as a result of Unix read
and write semantics, users can simply fread or fwrite bigger areas in
order to dump or store bigger memory areas.
There is currently no support for mmap, user-space interrupt management
and DMA buffers. They may be added in later versions, if the need
arises.
The example below shows raw access to a SPEC card programmed with its
golden FPGA file, that features an SDB structure at offset 256 - i.e.
64 words. The mezzanine's EEPROM in this case is not programmed, so the
default name is fmc-<bus><devfn>, and there are two cards in the system:
spusa.root# insmod fmc-chardev.ko
[ 1073.339332] spec 0000:02:00.0: Driver has no ID: matches all
[ 1073.345051] spec 0000:02:00.0: Created misc device "fmc-0200"
[ 1073.350821] spec 0000:04:00.0: Driver has no ID: matches all
[ 1073.356525] spec 0000:04:00.0: Created misc device "fmc-0400"
spusa.root# ls -l /dev/fmc*
crw------- 1 root root 10, 58 Nov 20 19:23 /dev/fmc-0200
crw------- 1 root root 10, 57 Nov 20 19:23 /dev/fmc-0400
spusa.root# dd bs=4 skip=64 count=1 if=/dev/fmc-0200 2> /dev/null | od -t x1z
0000000 2d 42 44 53 >-BDS<
0000004
The simple program tools/fmc-mem in this package can access an FMC char
device and read or write a word or a whole area. Actually, the program
is not specific to FMC at all, it just uses lseek, read and write.
Its first argument is the device name, the second the offset, the third
(if any) the value to write and the optional last argument that must
begin with "+" is the number of bytes to read or write. In case of
repeated reading data is written to stdout; repeated writes read from
stdin and the value argument is ignored.
The following examples show reading the SDB magic number and the first
SDB record from a SPEC device programmed with its golden image:
spusa.root# ./fmc-mem /dev/fmc-0200 100
5344422d
spusa.root# ./fmc-mem /dev/fmc-0200 100 +40 | od -Ax -t x1z
000000 2d 42 44 53 00 01 02 00 00 00 00 00 00 00 00 00 >-BDS............<
000010 00 00 00 00 ff 01 00 00 00 00 00 00 51 06 00 00 >............Q...<
000020 c9 42 a5 e6 02 00 00 00 11 05 12 20 2d 34 42 57 >.B......... -4BW<
000030 73 6f 72 43 72 61 62 73 49 53 47 2d 00 20 20 20 >sorCrabsISG-. <
000040
......@@ -40,4 +40,12 @@ config FMC_WRITE_EEPROM
its binary and the function carrier->reprogram to actually do it.
It is useful when the mezzanines are produced.
config FMC_CHARDEV
tristate "FMC mezzanine driver that registers a char device"
help
This driver matches every mezzanine device and allows user
space to read and write registers using a char device. It
can be used to write user-space drivers, or just get
aquainted with a mezzanine before writing its specific driver.
endif # FMC
......@@ -10,3 +10,4 @@ fmc-y += fmc-dump.o
obj-$(CONFIG_FMC_FAKEDEV) += fmc-fakedev.o
obj-$(CONFIG_FMC_TRIVIAL) += fmc-trivial.o
obj-$(CONFIG_FMC_WRITE_EEPROM) += fmc-write-eeprom.o
obj-$(CONFIG_FMC_CHARDEV) += fmc-chardev.o
/*
* Copyright (C) 2012 CERN (www.cern.ch)
* Author: Alessandro Rubini <rubini@gnudd.com>
*
* Released according to the GNU GPL, version 2 or any later version.
*
* This work is part of the White Rabbit project, a research effort led
* by CERN, the European Institute for Nuclear Research.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/spinlock.h>
#include <linux/fmc.h>
#include <linux/uaccess.h>
static LIST_HEAD(fc_devices);
static DEFINE_SPINLOCK(fc_lock);
struct fc_instance {
struct list_head list;
struct fmc_device *fmc;
struct miscdevice misc;
};
/* at open time, we must identify our device */
static int fc_open(struct inode *ino, struct file *f)
{
struct fmc_device *fmc;
struct fc_instance *fc;
int minor = iminor(ino);
list_for_each_entry(fc, &fc_devices, list)
if (fc->misc.minor == minor)
break;
if (fc->misc.minor != minor)
return -ENODEV;
fmc = fc->fmc;
if (try_module_get(fmc->owner) == 0)
return -ENODEV;
f->private_data = fmc;
return 0;
}
static int fc_release(struct inode *ino, struct file *f)
{
struct fmc_device *fmc = f->private_data;
module_put(fmc->owner);
return 0;
}
/* read and write are simple after the default llseek has been used */
static ssize_t fc_read(struct file *f, char __user *buf, size_t count,
loff_t *offp)
{
struct fmc_device *fmc = f->private_data;
unsigned long addr;
uint32_t val;
if (count < sizeof(val))
return -EINVAL;
count = sizeof(val);
addr = *offp;
if (addr > fmc->memlen)
return -ESPIPE; /* Illegal seek */
val = fmc_readl(fmc, addr);
if (copy_to_user(buf, &val, count))
return -EFAULT;
*offp += count;
return count;
}
static ssize_t fc_write(struct file *f, const char __user *buf, size_t count,
loff_t *offp)
{
struct fmc_device *fmc = f->private_data;
unsigned long addr;
uint32_t val;
if (count < sizeof(val))
return -EINVAL;
count = sizeof(val);
addr = *offp;
if (addr > fmc->memlen)
return -ESPIPE; /* Illegal seek */
if (copy_from_user(&val, buf, count))
return -EFAULT;
fmc_writel(fmc, val, addr);
*offp += count;
return count;
}
static const struct file_operations fc_fops = {
.owner = THIS_MODULE,
.open = fc_open,
.release = fc_release,
.llseek = generic_file_llseek,
.read = fc_read,
.write = fc_write,
};
/* Device part .. */
static int fc_probe(struct fmc_device *fmc);
static int fc_remove(struct fmc_device *fmc);
static struct fmc_driver fc_drv = {
.version = FMC_VERSION,
.driver.name = KBUILD_MODNAME,
.probe = fc_probe,
.remove = fc_remove,
/* no table: we want to match everything */
};
/* We accept the generic busid parameter */
FMC_PARAM_BUSID(fc_drv);
/* probe and remove must allocate and release a misc device */
static int fc_probe(struct fmc_device *fmc)
{
int ret;
int index = 0;
struct fc_instance *fc;
if (fmc->op->validate)
index = fmc->op->validate(fmc, &fc_drv);
if (index < 0)
return -EINVAL; /* not our device: invalid */
/* Create a char device: we want to create it anew */
fc = kzalloc(sizeof(*fc), GFP_KERNEL);
fc->fmc = fmc;
fc->misc.minor = MISC_DYNAMIC_MINOR;
fc->misc.fops = &fc_fops;
fc->misc.name = kstrdup(dev_name(&fmc->dev), GFP_KERNEL);
spin_lock(&fc_lock);
ret = misc_register(&fc->misc);
if (ret < 0) {
kfree(fc->misc.name);
kfree(fc);
} else {
list_add(&fc->list, &fc_devices);
}
spin_unlock(&fc_lock);
dev_info(&fc->fmc->dev, "Created misc device \"%s\"\n",
fc->misc.name);
return ret;
}
static int fc_remove(struct fmc_device *fmc)
{
struct fc_instance *fc;
list_for_each_entry(fc, &fc_devices, list)
if (fc->fmc == fmc)
break;
if (fc->fmc != fmc) {
dev_err(&fmc->dev, "remove called but not found\n");
return -ENODEV;
}
spin_lock(&fc_lock);
list_del(&fc->list);
misc_deregister(&fc->misc);
kfree(fc->misc.name);
kfree(fc);
spin_unlock(&fc_lock);
return 0;
}
static int fc_init(void)
{
int ret;
ret = fmc_driver_register(&fc_drv);
return ret;
}
static void fc_exit(void)
{
fmc_driver_unregister(&fc_drv);
}
module_init(fc_init);
module_exit(fc_exit);
MODULE_LICENSE("GPL");
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