--- /dev/null
+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
--- /dev/null
+/*
+ * 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");
projects / openwrt / staging / blogic.git / commitdiff