[RFC] [PATCH 5/10] Generic Watchdog Timer Driver

[Wim Van Sebroeck <wim@iguana.be>]

commit 1959ea403c69af855f5cd13e5c9b33123d2137b2
Author: Wim Van Sebroeck <wim@iguana.be>
Date:   Fri Jun 18 09:45:49 2010 +0000

    watchdog: WatchDog Timer Driver Core - Part 5
    
    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>

diff --git a/Documentation/watchdog/src/watchdog-with-timer-example.c b/Documentation/watchdog/src/watchdog-with-timer-example.c
index 6a4af47..f1d4f217 100644
--- a/Documentation/watchdog/src/watchdog-with-timer-example.c
+++ b/Documentation/watchdog/src/watchdog-with-timer-example.c
@@ -110,18 +110,27 @@ static int wdt_stop(struct watchdog_device *wdd)
 	return 0;
 }
 
+static int wdt_set_timeout(struct watchdog_device *wdd, int new_timeout)
+{
+	if (new_timeout < 1)
+		return -EINVAL;
+	return 0;
+}
+
 /*
  * The watchdog kernel structures
  */
 static const struct watchdog_info wdt_info = {
 	.identity =	DRV_NAME,
-	.options =	WDIOF_KEEPALIVEPING,
+	.options =	WDIOF_SETTIMEOUT |
+			WDIOF_KEEPALIVEPING,
 };
 
 static const struct watchdog_ops wdt_ops = {
 	.start =	wdt_start,
 	.stop =		wdt_stop,
 	.ping =		wdt_ping,
+	.set_timeout =	wdt_set_timeout,
 };
 
 static struct watchdog_device wdt_dev = {
@@ -139,6 +148,9 @@ static int __devinit wdt_probe(struct platform_device *pdev)
 
 	/* Register other stuff */
 
+	/* Set watchdog_device parameters */
+	wdt_dev.timeout = timeout;
+
 	/* Register the watchdog timer device */
 	res = register_watchdogdevice(&wdt_dev);
 	if (res) {
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index 3de69e7..f15e8d4 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -42,6 +42,7 @@ struct watchdog_device {
 	char *name;
 	const struct watchdog_info *info;
 	const struct watchdog_ops *ops;
+	int timeout;
 	int bootstatus;
 	long status;
 };
@@ -51,6 +52,7 @@ It contains following fields:
 * info: a pointer to a watchdog_info structure. This structure gives some
   additional information about the watchdog timer itself.
 * 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).
 * status: this field contains a number of status bits that give extra
@@ -67,6 +69,7 @@ struct watchdog_ops {
 	/* optional operations */
 	int (*ping)(struct watchdog_device *);
 	int (*status)(struct watchdog_device *);
+	int (*set_timeout)(struct watchdog_device *, int);
 };
 
 Some operations are mandatory and some are optional. The mandatory operations
@@ -102,6 +105,12 @@ 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 and an errno code on failure. 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 bit's that are defined are:
diff --git a/drivers/watchdog/core/watchdog_dev.c b/drivers/watchdog/core/watchdog_dev.c
index 2bf4f67..b80c6e6 100644
--- a/drivers/watchdog/core/watchdog_dev.c
+++ b/drivers/watchdog/core/watchdog_dev.c
@@ -221,6 +221,26 @@ 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 sent 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)
+			return put_user(wdd->timeout, p);
+		return -EOPNOTSUPP;
 	default:
 		return -ENOTTY;
 	}
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 736814f..e35f51f 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -70,6 +70,7 @@ struct watchdog_ops {
 	/* optional operations */
 	int (*ping)(struct watchdog_device *);
 	int (*status)(struct watchdog_device *);
+	int (*set_timeout)(struct watchdog_device *, int);
 };
 
 /* The structure that defines a watchdog device */
@@ -78,6 +79,7 @@ struct watchdog_device {
 	const struct watchdog_info *info;
 	const struct watchdog_ops *ops;
 	int bootstatus;
+	int timeout;
 	long status;
 #define WDOG_ACTIVE		0	/* is the watchdog running/active */
 #define WDOG_DEV_OPEN		1	/* is the watchdog opened via