From: Alan Cox <alan@xxxxxxxxxxxxxxx>
We keep the old /dev/watchdog interface file for the first watchdog via
miscdev. This is basically a cut and paste of the relevant interface code
from the rtc driver layer tweaked for watchdog.
Revised to fix problems noted by Hans de Goede
Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
---
drivers/watchdog/watchdog_dev.c | 231 ++++++++++++++++++++++++++++++++-------
include/linux/watchdog.h | 6 +
2 files changed, 193 insertions(+), 44 deletions(-)
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index c6e1b8d..40c557b 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -42,10 +42,12 @@
#include <linux/init.h> /* For __init/__exit/... */
#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
-/* make sure we only register one /dev/watchdog device */
-static unsigned long watchdog_dev_busy;
+static dev_t dog_devt; /* Watchdog device range */
+static unsigned long dog_mask; /* Watchdogs that are in use */
/* the watchdog device behind /dev/watchdog */
-static struct watchdog_device *wdd;
+static struct watchdog_device *old_wdd;
+
+#define DOG_MAX 32 /* assign_id must be changed to boost this */
/*
* watchdog_ping: ping the watchdog.
@@ -136,6 +138,7 @@ static int watchdog_stop(struct watchdog_device *wddev)
static ssize_t watchdog_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
+ struct watchdog_device *wdd = file->private_data;
size_t i;
char c;
@@ -175,6 +178,7 @@ static ssize_t watchdog_write(struct file *file, const char __user *data,
static long watchdog_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
+ struct watchdog_device *wdd = file->private_data;
void __user *argp = (void __user *)arg;
int __user *p = argp;
unsigned int val;
@@ -251,7 +255,8 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
* it can only be opened once.
*/
-static int watchdog_open(struct inode *inode, struct file *file)
+static int watchdog_do_open(struct watchdog_device *wdd,
+ struct inode *inode, struct file *file)
{
int err = -EBUSY;
@@ -270,6 +275,8 @@ static int watchdog_open(struct inode *inode, struct file *file)
if (err < 0)
goto out_mod;
+ file->private_data = wdd;
+
/* dev/watchdog is a virtual (and thus non-seekable) filesystem */
return nonseekable_open(inode, file);
@@ -281,7 +288,40 @@ out:
}
/*
- * watchdog_release: release the /dev/watchdog device.
+ * watchdog_open: open the /dev/watchdog device.
+ * @inode: inode of device
+ * @file: file handle to device
+ *
+ * When the /dev/watchdog device gets opened, we start the watchdog.
+ * Watch out: the /dev/watchdog device is single open, so we make sure
+ * it can only be opened once.
+ */
+
+static int watchdog_open(struct inode *inode, struct file *file)
+{
+ return watchdog_do_open(old_wdd, inode, file);
+}
+
+/*
+ * watchdog_mopen: open the newer watchdog devices.
+ * @inode: inode of device
+ * @file: file handle to device
+ *
+ * When the watchdog device gets opened, we start the watchdog.
+ * Watch out: the /dev/watchdog device is single open, so we make sure
+ * it can only be opened once.
+ */
+
+static int watchdog_mopen(struct inode *inode, struct file *file)
+{
+ struct watchdog_device *wdd = container_of(inode->i_cdev,
+ struct watchdog_device, cdev);
+
+ return watchdog_do_open(wdd, inode, file);
+}
+
+/*
+ * watchdog_release: release the watchdog device.
* @inode: inode of device
* @file: file handle to device
*
@@ -292,6 +332,7 @@ out:
static int watchdog_release(struct inode *inode, struct file *file)
{
+ struct watchdog_device *wdd = file->private_data;
int err = -EBUSY;
/*
@@ -326,69 +367,171 @@ static const struct file_operations watchdog_fops = {
.release = watchdog_release,
};
+static const struct file_operations watchdog_multi_fops = {
+ .owner = THIS_MODULE,
+ .write = watchdog_write,
+ .unlocked_ioctl = watchdog_ioctl,
+ .open = watchdog_mopen,
+ .release = watchdog_release,
+};
+
static struct miscdevice watchdog_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &watchdog_fops,
};
-/*
- * watchdog_dev_register:
- * @watchdog: watchdog device
+/**
+ * watchdog_assign_id - pick a free watchdog ident
+ * @watchdog: the watchdog device
+ * @first: number to scan from
*
- * Register a watchdog device as /dev/watchdog. /dev/watchdog
- * is actually a miscdevice and thus we set it up like that.
+ * Assign a watchdog number to the device. For the moment we support
+ * a starting offset so that a legacy watchdog can be worked around
*/
+static int watchdog_assign_id(struct watchdog_device *watchdog, int first)
+{
+ int i;
+ for (i = first; i < DOG_MAX; i ++) {
+ if (test_and_set_bit(i, &dog_mask) == 0) {
+ watchdog->id = i;
+ return i;
+ }
+ }
+ pr_err("no free watchdog slots.\n");
+ return -EBUSY;
+}
-int watchdog_dev_register(struct watchdog_device *watchdog)
+/**
+ * watchdog_release_id - release a watchdg id
+ * @watchdog: the watchdog device
+ *
+ * Release the identifier associated with this watchdog. All cdev
+ * resources must have been released first.
+ */
+static void watchdog_release_id(struct watchdog_device *watchdog)
+{
+ clear_bit(watchdog->id, &dog_mask);
+}
+
+/**
+ * watchdog_add_device - add a watchdog device
+ * @watchdog: the watchdog device
+ *
+ * Add a watchdog device node to the system and set up all the
+ * needed structures.
+ */
+static int watchdog_add_device(struct watchdog_device *watchdog)
{
int err;
- /* Only one device can register for /dev/watchdog */
- if (test_and_set_bit(0, &watchdog_dev_busy)) {
- pr_err("only one watchdog can use /dev/watchdog\n");
- return -EBUSY;
- }
+ /* Fill in the data structures */
+ watchdog->devt = MKDEV(MAJOR(dog_devt), watchdog->id);
+ watchdog->cdev.owner = watchdog->ops->owner;
+ cdev_init(&watchdog->cdev, &watchdog_multi_fops);
- wdd = watchdog;
+ /* Add the device */
+ err = cdev_add(&watchdog->cdev, watchdog->devt, 1);
+ if (err)
+ pr_err("watchdog%d unable to add device %d:%d\n",
+ watchdog->id, MAJOR(dog_devt), watchdog->id);
+ return err;
+}
- err = misc_register(&watchdog_miscdev);
- if (err != 0) {
- pr_err("%s: cannot register miscdev on minor=%d (err=%d)\n",
- watchdog->info->identity, WATCHDOG_MINOR, err);
- goto out;
- }
+/**
+ * watchdog_del_device - delete a watchdog device
+ * @watchdog: the watchdog device
+ *
+ * Delete a watchdog device cdev object
+ */
+static void watchdog_del_device(struct watchdog_device *watchdog)
+{
+ cdev_del(&watchdog->cdev);
+}
- return 0;
+/**
+ * watchdog_dev_register - register a watchdog
+ * @watchdog: watchdog device
+ *
+ * Register a watchdog device including handling the legacy
+ * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
+ * thus we set it up like that.
+ */
+int watchdog_dev_register(struct watchdog_device *watchdog)
+{
+ int err;
-out:
- wdd = NULL;
- clear_bit(0, &watchdog_dev_busy);
+ err = watchdog_assign_id(watchdog, 0);
+ if (err < 0)
+ return err;
+ if (err == 0) {
+ err = misc_register(&watchdog_miscdev);
+ if (err == 0)
+ old_wdd = watchdog;
+ else {
+ pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
+ watchdog->info->identity, WATCHDOG_MINOR, err);
+ if (err == -EBUSY) {
+ pr_err("%s: probably a legacy watchdog module is present.\n",
+ watchdog->info->identity);
+ watchdog_release_id(watchdog);
+ err = watchdog_assign_id(watchdog, 1);
+ }
+ if (err < 0)
+ return err;
+ }
+ }
+ err = watchdog_add_device(watchdog);
+ if (err < 0) {
+ if (watchdog->id == 0) {
+ misc_deregister(&watchdog_miscdev);
+ old_wdd = NULL;
+ }
+ watchdog_release_id(watchdog);
+ }
return err;
}
-/*
- * watchdog_dev_unregister:
+/**
+ * watchdog_dev_unregister - unregister a watchdog
* @watchdog: watchdog device
*
- * Deregister the /dev/watchdog device.
+ * Unregister the watchdog and if needed the legacy /dev/watchdog device.
*/
-
int watchdog_dev_unregister(struct watchdog_device *watchdog)
{
- /* Check that a watchdog device was registered in the past */
- if (!test_bit(0, &watchdog_dev_busy) || !wdd)
- return -ENODEV;
-
- /* We can only unregister the watchdog device that was registered */
- if (watchdog != wdd) {
- pr_err("%s: watchdog was not registered as /dev/watchdog\n",
- watchdog->info->identity);
- return -ENODEV;
+ watchdog_del_device(watchdog);
+ if (watchdog->id == 0) {
+ misc_deregister(&watchdog_miscdev);
+ old_wdd = NULL;
}
-
- misc_deregister(&watchdog_miscdev);
- wdd = NULL;
- clear_bit(0, &watchdog_dev_busy);
+ watchdog_release_id(watchdog);
return 0;
}
+
+/**
+ * watchdog_init - module init call
+ *
+ * Allocate a range of chardev nodes to use for watchdog devices
+ */
+int __init watchdog_init(void)
+{
+ int err = alloc_chrdev_region(&dog_devt, 0, DOG_MAX, "watchdog");
+ if (err < 0)
+ pr_err("watchdog: unable to allocate char dev region\n");
+ return err;
+}
+
+/**
+ * watchdog_exit - module exit
+ *
+ * Release the range of chardev nodes used for watchdog devices
+ */
+void __exit watchdog_exit(void)
+{
+ unregister_chrdev_region(dog_devt, DOG_MAX);
+}
+
+module_init(watchdog_init);
+module_exit(watchdog_exit);
+
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index de75167..0d5c3af 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -54,6 +54,8 @@ struct watchdog_info {
#ifdef __KERNEL__
#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/cdev.h>
struct watchdog_ops;
struct watchdog_device;
@@ -103,6 +105,10 @@ struct watchdog_ops {
* via the watchdog_set_drvdata and watchdog_get_drvdata helpers.
*/
struct watchdog_device {
+ struct cdev cdev; /* Character device */
+ dev_t devt; /* Our device */
+ int id; /* Watchdog id */
+
const struct watchdog_info *info;
const struct watchdog_ops *ops;
unsigned int bootstatus;
--
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