watchdog: WatchDog Timer Driver Core - Add WDIOC_SETTIMEOUT and WDIOC_GETTIMEOUT ioctl

This part add's the WDIOC_SETTIMEOUT and WDIOC_GETTIMEOUT ioctl
functionality to the WatchDog Timer Driver Core framework.

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>

Documentation/watchdog/watchdog-kernel-api.txt

@@ -42,6 +42,7 @@ struct watchdog_device {
 	const struct watchdog_info *info;
 	const struct watchdog_ops *ops;
 	unsigned int bootstatus;
+	unsigned int timeout;
 	void *driver_data;
 	unsigned long status;
 };
@@ -50,6 +51,7 @@ 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.
+* timeout: the watchdog timer's timeout value (in seconds).
 * bootstatus: status of the device after booting (reported with watchdog
   WDIOF_* status bits).
 * driver_data: a pointer to the drivers private data of a watchdog device.
@@ -70,6 +72,7 @@ struct watchdog_ops {
 	/* optional operations */
 	int (*ping)(struct watchdog_device *);
 	unsigned int (*status)(struct watchdog_device *);
+	int (*set_timeout)(struct watchdog_device *, unsigned int);
 };
 
 It is important that you first define the module owner of the watchdog timer
@@ -107,6 +110,13 @@ they are supported. These optional routines/operations are:
   info structure).
 * status: this routine checks the status of the watchdog timer device. The
   status of the device is reported with watchdog WDIOF_* status flags/bits.
+* set_timeout: this routine checks and changes the timeout of the watchdog
+  timer device. It returns 0 on success, -EINVAL for "parameter out of range"
+  and -EIO for "could not write value to the watchdog". On success the timeout
+  value of the watchdog_device will be changed to the value that was just used
+  to re-program the watchdog timer device.
+  (Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
+  watchdog's info structure).
 
 The status bits should (preferably) be set with the set_bit and clear_bit alike
 bit-operations. The status bits that are defined are:

drivers/watchdog/watchdog_dev.c

@@ -190,6 +190,26 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
 			return -EOPNOTSUPP;
 		watchdog_ping(wdd);
 		return 0;
+	case WDIOC_SETTIMEOUT:
+		if ((wdd->ops->set_timeout == NULL) ||
+		    !(wdd->info->options & WDIOF_SETTIMEOUT))
+			return -EOPNOTSUPP;
+		if (get_user(val, p))
+			return -EFAULT;
+		err = wdd->ops->set_timeout(wdd, val);
+		if (err < 0)
+			return err;
+		wdd->timeout = val;
+		/* If the watchdog is active then we send a keepalive ping
+		 * to make sure that the watchdog keep's running (and if
+		 * possible that it takes the new timeout) */
+		watchdog_ping(wdd);
+		/* Fall */
+	case WDIOC_GETTIMEOUT:
+		/* timeout == 0 means that we don't know the timeout */
+		if (wdd->timeout == 0)
+			return -EOPNOTSUPP;
+		return put_user(wdd->timeout, p);
 	default:
 		return -ENOTTY;
 	}

include/linux/watchdog.h

@@ -69,6 +69,7 @@ struct watchdog_device;
  * @stop:	The routine for stopping the watchdog device.
  * @ping:	The routine that sends a keepalive ping to the watchdog device.
  * @status:	The routine that shows the status of the watchdog device.
+ * @set_timeout:The routine for setting the watchdog devices timeout value.
  *
  * The watchdog_ops structure contains a list of low-level operations
  * that control a watchdog device. It also contains the module that owns
@@ -83,6 +84,7 @@ struct watchdog_ops {
 	/* optional operations */
 	int (*ping)(struct watchdog_device *);
 	unsigned int (*status)(struct watchdog_device *);
+	int (*set_timeout)(struct watchdog_device *, unsigned int);
 };
 
 /** struct watchdog_device - The structure that defines a watchdog device
@@ -90,6 +92,7 @@ struct watchdog_ops {
  * @info:	Pointer to a watchdog_info structure.
  * @ops:	Pointer to the list of watchdog operations.
  * @bootstatus:	Status of the watchdog device at boot.
+ * @timeout:	The watchdog devices timeout value.
  * @driver-data:Pointer to the drivers private data.
  * @status:	Field that contains the devices internal status bits.
  *
@@ -103,6 +106,7 @@ struct watchdog_device {
 	const struct watchdog_info *info;
 	const struct watchdog_ops *ops;
 	unsigned int bootstatus;
+	unsigned int timeout;
 	void *driver_data;
 	unsigned long status;
 /* Bit numbers for status flags */