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: Alessandro Rubini <rubini@gnudd.com>
Acked-by: Juan David Gonzalez Cobas <dcobas@cern.ch>
Acked-by: Emilio G. Cota <cota@braap.org>
Acked-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/fmc/Kconfig b/drivers/fmc/Kconfig
index 2bb1953..c01cf45 100644
--- a/drivers/fmc/Kconfig
+++ b/drivers/fmc/Kconfig
@@ -40,4 +40,12 @@
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
diff --git a/drivers/fmc/Makefile b/drivers/fmc/Makefile
index 13701fa..b945291 100644
--- a/drivers/fmc/Makefile
+++ b/drivers/fmc/Makefile
@@ -10,3 +10,4 @@
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
diff --git a/drivers/fmc/fmc-chardev.c b/drivers/fmc/fmc-chardev.c
new file mode 100644
index 0000000..b071039
--- /dev/null
+++ b/drivers/fmc/fmc-chardev.c
@@ -0,0 +1,197 @@
+/*
+ * 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");