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.
Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
Signed-off-by: Wim Van Sebroeck <wim@xxxxxxxxx>
Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
---
V2 (by Wim):
1. Clean split between core and dev related stuff.
2. Use ida instead of the watchdog_assign/release_id code.
3. Rest it's basically the code that Alan produced with some minor changes
with the comments that Hans made.
V3: (by Tomas)
1. Fix compilation error caused by missing include to watchdog_dev.h
2. Add documentation changes to be part of this patch
3. Make init and exit module functions static (fixes sparse error)
4. Fix minor checkpatch.pl complains
Documentation/watchdog/watchdog-kernel-api.txt | 6 +
drivers/watchdog/watchdog_core.c | 29 +++++-
drivers/watchdog/watchdog_dev.c | 131 ++++++++++++++++--------
drivers/watchdog/watchdog_dev.h | 2 +
include/linux/watchdog.h | 6 +
5 files changed, 125 insertions(+), 49 deletions(-)
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index 227f6cd..2d28950 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -46,10 +46,13 @@ struct watchdog_device {
unsigned int min_timeout;
unsigned int max_timeout;
void *driver_data;
+ int id;
+ struct cdev cdev;
unsigned long status;
};
It contains following fields:
+
* info: a pointer to a watchdog_info structure. This structure gives some
additional information about the watchdog timer itself. (Like it's unique name)
* ops: a pointer to the list of watchdog operations that the watchdog supports.
@@ -61,6 +64,9 @@ It contains following fields:
* driver_data: a pointer to the drivers private data of a watchdog device.
This data should only be accessed via the watchdog_set_drvadata and
watchdog_get_drvdata routines.
+* id: set by watchdog_register_device. id 0 is special, it has both cdev with
+ dynamic major and minor 0 (/dev/watchdog0) and as well as the old miscdev /dev/watchdog
+* cdev: cdev for the dynamic major /dev/watchdog<id> device nodes
* status: this field contains a number of status bits that give extra
information about the status of the device (Like: is the watchdog timer
running/active, is the nowayout bit set, is the device opened via
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index 14d768b..f6f3828 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -34,9 +34,12 @@
#include <linux/kernel.h> /* For printk/panic/... */
#include <linux/watchdog.h> /* For watchdog specific items */
#include <linux/init.h> /* For __init/__exit/... */
+#include <linux/idr.h> /* For ida_* macros */
#include "watchdog_dev.h" /* For watchdog_dev_register/... */
+static DEFINE_IDA(watchdog_ida);
+
/**
* watchdog_register_device() - register a watchdog device
* @wdd: watchdog device
@@ -49,7 +52,7 @@
*/
int watchdog_register_device(struct watchdog_device *wdd)
{
- int ret;
+ int ret, id;
if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
return -EINVAL;
@@ -74,11 +77,28 @@ int watchdog_register_device(struct watchdog_device *wdd)
* corrupted in a later stage then we expect a kernel panic!
*/
- /* We only support 1 watchdog device via the /dev/watchdog interface */
+ id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
+ if (id < 0)
+ return id;
+ wdd->id = id;
+
ret = watchdog_dev_register(wdd);
if (ret) {
- pr_err("error registering /dev/watchdog (err=%d)\n", ret);
- return ret;
+ ida_simple_remove(&watchdog_ida, id);
+ if (!(id == 0 || ret == -EBUSY))
+ return ret;
+
+ /* Retry in case a legacy watchdog module exists */
+ id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
+ if (id < 0)
+ return id;
+ wdd->id = id;
+
+ ret = watchdog_dev_register(wdd);
+ if (ret) {
+ ida_simple_remove(&watchdog_ida, id);
+ return ret;
+ }
}
return 0;
@@ -102,6 +122,7 @@ void watchdog_unregister_device(struct watchdog_device *wdd)
ret = watchdog_dev_unregister(wdd);
if (ret)
pr_err("error unregistering /dev/watchdog (err=%d)\n", ret);
+ ida_simple_remove(&watchdog_ida, wdd->id);
}
EXPORT_SYMBOL_GPL(watchdog_unregister_device);
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 8558da9..4ce3b78 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -41,11 +41,12 @@
#include <linux/miscdevice.h> /* For handling misc devices */
#include <linux/init.h> /* For __init/__exit/... */
#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
+#include "watchdog_dev.h"
-/* make sure we only register one /dev/watchdog device */
-static unsigned long watchdog_dev_busy;
/* the watchdog device behind /dev/watchdog */
-static struct watchdog_device *wdd;
+static struct watchdog_device *old_wdd;
+/* the dev_t structure to store the dynamically allocated watchdog devices */
+static dev_t watchdog_devt;
/*
* watchdog_ping: ping the watchdog.
@@ -136,6 +137,7 @@ 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 +177,7 @@ 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;
@@ -247,11 +250,11 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
}
/*
- * watchdog_open: open the /dev/watchdog device.
+ * watchdog_open: open the /dev/watchdog* devices.
* @inode: inode of device
* @file: file handle to device
*
- * When the /dev/watchdog device gets opened, we start the watchdog.
+ * 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.
*/
@@ -259,6 +262,13 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
static int watchdog_open(struct inode *inode, struct file *file)
{
int err = -EBUSY;
+ struct watchdog_device *wdd;
+
+ /* Get the corresponding watchdog device */
+ if (imajor(inode) == MISC_MAJOR)
+ wdd = old_wdd;
+ else
+ wdd = container_of(inode->i_cdev, struct watchdog_device, cdev);
/* the watchdog is single open! */
if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
@@ -275,6 +285,8 @@ 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);
@@ -286,9 +298,9 @@ out:
}
/*
- * watchdog_release: release the /dev/watchdog device.
- * @inode: inode of device
- * @file: file handle to device
+ * watchdog_release: release the watchdog device.
+ * @inode: inode of device
+ * @file: file handle to device
*
* This is the code for when /dev/watchdog gets closed. We will only
* stop the watchdog when we have received the magic char (and nowayout
@@ -297,6 +309,7 @@ out:
static int watchdog_release(struct inode *inode, struct file *file)
{
+ struct watchdog_device *wdd = file->private_data;
int err = -EBUSY;
/*
@@ -338,62 +351,90 @@ static struct miscdevice watchdog_miscdev = {
};
/*
- * watchdog_dev_register:
+ * watchdog_dev_register: register a watchdog device
* @watchdog: watchdog device
*
- * Register a watchdog device as /dev/watchdog. /dev/watchdog
- * is actually a miscdevice and thus we set it up like that.
+ * 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;
-
- /* 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;
+ int err, devno;
+
+ if (watchdog->id == 0) {
+ 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);
+ if (err == -EBUSY)
+ pr_err("%s: a legacy watchdog module is probably present.\n",
+ watchdog->info->identity);
+ return err;
+ }
+ old_wdd = watchdog;
}
- wdd = watchdog;
-
- 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;
+ /* Fill in the data structures */
+ devno = MKDEV(MAJOR(watchdog_devt), watchdog->id);
+ cdev_init(&watchdog->cdev, &watchdog_fops);
+ watchdog->cdev.owner = watchdog->ops->owner;
+
+ /* Add the device */
+ err = cdev_add(&watchdog->cdev, devno, 1);
+ if (err) {
+ pr_err("watchdog%d unable to add device %d:%d\n",
+ watchdog->id, MAJOR(watchdog_devt), watchdog->id);
+ if (watchdog->id == 0) {
+ misc_deregister(&watchdog_miscdev);
+ old_wdd = NULL;
+ }
}
-
- return 0;
-
-out:
- wdd = NULL;
- clear_bit(0, &watchdog_dev_busy);
return err;
}
/*
- * watchdog_dev_unregister:
+ * watchdog_dev_unregister: unregister a watchdog device
* @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;
+ cdev_del(&watchdog->cdev);
+ if (watchdog->id == 0) {
+ misc_deregister(&watchdog_miscdev);
+ old_wdd = NULL;
}
-
- misc_deregister(&watchdog_miscdev);
- wdd = NULL;
- clear_bit(0, &watchdog_dev_busy);
return 0;
}
+
+/*
+ * watchdog_init: module init call
+ *
+ * Allocate a range of chardev nodes to use for watchdog devices
+ */
+
+static int __init watchdog_init(void)
+{
+ int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "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
+ */
+
+static void __exit watchdog_exit(void)
+{
+ unregister_chrdev_region(watchdog_devt, MAX_DOGS);
+}
+
+module_init(watchdog_init);
+module_exit(watchdog_exit);
diff --git a/drivers/watchdog/watchdog_dev.h b/drivers/watchdog/watchdog_dev.h
index bc7612b..0eb8f6f 100644
--- a/drivers/watchdog/watchdog_dev.h
+++ b/drivers/watchdog/watchdog_dev.h
@@ -26,6 +26,8 @@
* This material is provided "AS-IS" and at no charge.
*/
+#define MAX_DOGS 32 /* Maximum number of watchdog devices */
+
/*
* Functions/procedures to be called by the core
*/
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index ac40716..1397cbc 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;
@@ -96,6 +98,8 @@ struct watchdog_ops {
* @min_timeout:The watchdog devices minimum timeout value.
* @max_timeout:The watchdog devices maximum timeout value.
* @driver-data:Pointer to the drivers private data.
+ * @id: The watchdog's ID.
+ * @cdev: The watchdog's Character device.
* @status: Field that contains the devices internal status bits.
*
* The watchdog_device structure contains all information about a
@@ -112,6 +116,8 @@ struct watchdog_device {
unsigned int min_timeout;
unsigned int max_timeout;
void *driver_data;
+ int id;
+ struct cdev cdev;
unsigned long status;
/* Bit numbers for status flags */
#define WDOG_ACTIVE 0 /* Is the watchdog running/active */
--
1.7.4.4
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