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Date: Sat, 18 Jun 2011 19:23:01 +0200
From: Wim Van Sebroeck <wim@...ana.be>
To: LKML <linux-kernel@...r.kernel.org>,
Linux Watchdog Mailing List <linux-watchdog@...r.kernel.org>
Cc: Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: [PATCH 4/10 v2] Generic Watchdog Timer Driver
watchdog: WatchDog Timer Driver Core - Part 4
This part add's the WDIOC_SETOPTIONS ioctl functionality
to the WatchDog Timer Driver Core framework.
Signed-off-by: Alan Cox <alan@...rguk.ukuu.org.uk>
Signed-off-by: Wim Van Sebroeck <wim@...ana.be>
diff -urN linux-2.6.38-generic-part3/Documentation/watchdog/src/watchdog-with-timer-example.c linux-2.6.38-generic-part4/Documentation/watchdog/src/watchdog-with-timer-example.c
--- linux-2.6.38-generic-part3/Documentation/watchdog/src/watchdog-with-timer-example.c 2011-06-16 20:07:53.631174037 +0200
+++ linux-2.6.38-generic-part4/Documentation/watchdog/src/watchdog-with-timer-example.c 2011-06-16 20:08:16.987178248 +0200
@@ -45,11 +45,11 @@
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. "
"(default = " __MODULE_STRING(WDT_TIMEOUT) ")");
+static struct watchdog_device wdt_dev;
static void wdt_timer_tick(unsigned long data);
static DEFINE_TIMER(timer, wdt_timer_tick, 0, 0);
/* The timer that pings the watchdog */
static unsigned long next_heartbeat; /* the next_heartbeat for the timer */
-static unsigned long running; /* is watchdog running for userspace? */
static struct platform_device *wdt_platform_device;
@@ -73,7 +73,7 @@
static void wdt_timer_tick(unsigned long data)
{
if (time_before(jiffies, next_heartbeat) ||
- (!running)) {
+ (!test_bit(WDOG_ACTIVE, &wdt_dev.status))) {
wdt_reset();
mod_timer(&timer, jiffies + WDT_HEARTBEAT);
} else
@@ -99,7 +99,6 @@
/* Start the watchdog timer hardware here */
pr_info("wdt_start\n");
- running = 1;
return 0;
}
@@ -108,7 +107,6 @@
/* The watchdog timer hardware can not be stopped... */
pr_info("wdt_stop\n");
- running = 0;
return 0;
}
diff -urN linux-2.6.38-generic-part3/Documentation/watchdog/watchdog-kernel-api.txt linux-2.6.38-generic-part4/Documentation/watchdog/watchdog-kernel-api.txt
--- linux-2.6.38-generic-part3/Documentation/watchdog/watchdog-kernel-api.txt 2011-06-16 18:44:20.747179936 +0200
+++ linux-2.6.38-generic-part4/Documentation/watchdog/watchdog-kernel-api.txt 2011-06-16 19:14:34.603180137 +0200
@@ -54,8 +54,9 @@
* 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
- information about the status of the device (Like: is the device opened via
- the /dev/watchdog interface or not, ...)
+ information about the status of the device (Like: is the watchdog timer
+ running/active, is the device opened via the /dev/watchdog interface or not,
+ ...)
The list of watchdog operations is defined as:
@@ -109,6 +110,10 @@
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:
+* WDOG_ACTIVE: this status bit indicates whether or not a watchdog timer device
+ is active or not. When the watchdog is active after booting, then you should
+ set this status bit (Note: when you register the watchdog timer device with
+ this bit set, then opening /dev/watchdog will skip the start operation)
* WDOG_DEV_OPEN: this status bit shows whether or not the watchdog device
was opened via /dev/watchdog.
(This bit should only be used by the WatchDog Timer Driver Core).
diff -urN linux-2.6.38-generic-part3/drivers/watchdog/core/watchdog_dev.c linux-2.6.38-generic-part4/drivers/watchdog/core/watchdog_dev.c
--- linux-2.6.38-generic-part3/drivers/watchdog/core/watchdog_dev.c 2011-06-16 19:35:22.415178710 +0200
+++ linux-2.6.38-generic-part4/drivers/watchdog/core/watchdog_dev.c 2011-06-16 19:36:11.571178880 +0200
@@ -82,14 +82,64 @@
* If the watchdog has no own ping operation then it needs to be
* restarted via the start operation. This wrapper function does
* exactly that.
+ * We only ping when the watchdog device is running.
*/
static int watchdog_ping(struct watchdog_device *wddev)
{
- if (wddev->ops->ping)
- return wddev->ops->ping(wddev); /* ping the watchdog */
- else
- return wddev->ops->start(wddev); /* restart the watchdog */
+ if (test_bit(WDOG_ACTIVE, &wdd->status)) {
+ if (wddev->ops->ping)
+ return wddev->ops->ping(wddev); /* ping the watchdog */
+ else
+ return wddev->ops->start(wddev); /* restart watchdog */
+ }
+ return 0;
+}
+
+/*
+ * watchdog_start: wrapper to start the watchdog.
+ * @wddev: the watchdog device to start
+ *
+ * Start the watchdog if it is not active and mark it active.
+ * This function returns zero on success or a negative errno code for
+ * failure.
+ */
+
+static int watchdog_start(struct watchdog_device *wddev)
+{
+ int err;
+
+ if (!test_bit(WDOG_ACTIVE, &wdd->status)) {
+ err = wddev->ops->start(wddev);
+ if (err < 0)
+ return err;
+
+ set_bit(WDOG_ACTIVE, &wdd->status);
+ }
+ return 0;
+}
+
+/*
+ * watchdog_stop: wrapper to stop the watchdog.
+ * @wddev: the watchdog device to stop
+ *
+ * Stop the watchdog if it is still active and unmark it active.
+ * This function returns zero on success or a negative errno code for
+ * failure.
+ */
+
+static int watchdog_stop(struct watchdog_device *wddev)
+{
+ int err;
+
+ if (test_bit(WDOG_ACTIVE, &wdd->status)) {
+ err = wddev->ops->stop(wddev);
+ if (err < 0)
+ return err;
+
+ clear_bit(WDOG_ACTIVE, &wdd->status);
+ }
+ return 0;
}
/*
@@ -140,6 +190,7 @@
void __user *argp = (void __user *)arg;
int __user *p = argp;
int val = 0;
+ int err;
trace("%p, %u, %li", file, cmd, arg);
@@ -153,6 +204,20 @@
return put_user(val, p);
case WDIOC_GETBOOTSTATUS:
return put_user(wdd->bootstatus, p);
+ case WDIOC_SETOPTIONS:
+ if (get_user(val, p))
+ return -EFAULT;
+ if (val & WDIOS_DISABLECARD) {
+ err = watchdog_stop(wdd);
+ if (err < 0)
+ return err;
+ }
+ if (val & WDIOS_ENABLECARD) {
+ err = watchdog_start(wdd);
+ if (err < 0)
+ return err;
+ }
+ return 0;
case WDIOC_KEEPALIVE:
if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
return -EOPNOTSUPP;
@@ -190,7 +255,7 @@
goto out;
/* start the watchdog */
- err = wdd->ops->start(wdd);
+ err = watchdog_start(wdd);
if (err < 0)
goto out_mod;
@@ -219,8 +284,8 @@
trace("%p, %p", inode, file);
/* stop the watchdog */
- err = wdd->ops->stop(wdd);
- if (err != 0) {
+ err = watchdog_stop(wdd);
+ if (err < 0) {
pr_crit("%s: not stopping watchdog!\n", wdd->name);
watchdog_ping(wdd);
}
diff -urN linux-2.6.38-generic-part3/include/linux/watchdog.h linux-2.6.38-generic-part4/include/linux/watchdog.h
--- linux-2.6.38-generic-part3/include/linux/watchdog.h 2011-06-16 16:57:31.388541823 +0200
+++ linux-2.6.38-generic-part4/include/linux/watchdog.h 2011-06-16 19:14:34.603180137 +0200
@@ -80,6 +80,7 @@
const struct watchdog_ops *ops;
int bootstatus;
long status;
+#define WDOG_ACTIVE 0 /* is the watchdog running/active */
#define WDOG_DEV_OPEN 1 /* is the watchdog opened via
* /dev/watchdog */
};
--
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