[PATCH v3 1/2] watchdog: add WDIOC_SETPRETIMEOUT and WDIOC_GETPRETIMEOUT

[Robin Gong]

Since the watchdog common framework centrialize the IOCTL interfaces of
device driver now, the SETPRETIMEOUT and GETPRETIMEOUT need to be added
in the common code.

Signed-off-by: Robin Gong <b38343@xxxxxxxxxxxxx>
---
 Documentation/watchdog/watchdog-kernel-api.txt | 12 +++++++++
 drivers/watchdog/watchdog_dev.c                | 37 ++++++++++++++++++++++++++
 include/linux/watchdog.h                       | 11 ++++++++
 3 files changed, 60 insertions(+)

diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index d8b0d33..20aa841 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -51,6 +51,7 @@ struct watchdog_device {
 	const struct watchdog_ops *ops;
 	unsigned int bootstatus;
 	unsigned int timeout;
+	unsigned int pretimeout;
 	unsigned int min_timeout;
 	unsigned int max_timeout;
 	void *driver_data;
@@ -73,6 +74,7 @@ It contains following fields:
   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).
+* pretimeout:	The watchdog devices pre_timeout value.
 * min_timeout: the watchdog timer's minimum timeout value (in seconds).
 * max_timeout: the watchdog timer's maximum timeout value (in seconds).
 * bootstatus: status of the device after booting (reported with watchdog
@@ -99,6 +101,7 @@ struct watchdog_ops {
 	int (*ping)(struct watchdog_device *);
 	unsigned int (*status)(struct watchdog_device *);
 	int (*set_timeout)(struct watchdog_device *, unsigned int);
+	int (*set_pretimeout)(struct watchdog_device *, unsigned int);
 	unsigned int (*get_timeleft)(struct watchdog_device *);
 	void (*ref)(struct watchdog_device *);
 	void (*unref)(struct watchdog_device *);
@@ -163,6 +166,15 @@ they are supported. These optional routines/operations are:
   because the watchdog does not necessarily has a 1 second resolution).
   (Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
   watchdog's info structure).
+* set_pretimeout: this routine check and changes the pre_timeout value of
+  the watchdog, because some watchdog device can trigger the pre_timeout
+  interrupt before watchdog timeout event happened, so that we have chance
+  to save some critical information or something else before watchdog
+  triggered. The pre_timeout value means the number of seconds before
+  watchdog timeout.It returns 0 on success, -EINVAL for "parameter out
+  of range" and and -EIO for "could not write value to the watchdog".
+  (Note: the WDIOF_SETPRETIMEOUT needs to be set in the options field of the
+  watchdog's info structure).
 * get_timeleft: this routines returns the time that's left before a reset.
 * ref: the operation that calls kref_get on the kref of a dynamically
   allocated watchdog_device struct.
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 6aaefba..f4a02e5 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -218,6 +218,37 @@ out_timeout:
 }
 
 /*
+ *	watchdog_set_pretimeout: set the watchdog timer pretimeout
+ *	@wddev: the watchdog device to set the timeout for
+ *	@timeout: pretimeout to set in seconds
+ */
+
+static int watchdog_set_pretimeout(struct watchdog_device *wddev,
+				   unsigned int timeout)
+{
+	int err;
+
+	if (!wddev->ops->set_pretimeout ||
+	    !(wddev->info->options & WDIOF_PRETIMEOUT))
+		return -EOPNOTSUPP;
+	if (watchdog_pretimeout_invalid(wddev, timeout))
+		return -EINVAL;
+
+	mutex_lock(&wddev->lock);
+
+	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+		err = -ENODEV;
+		goto out_timeout;
+	}
+
+	err = wddev->ops->set_pretimeout(wddev, timeout);
+
+out_timeout:
+	mutex_unlock(&wddev->lock);
+	return err;
+}
+
+/*
  *	watchdog_get_timeleft: wrapper to get the time left before a reboot
  *	@wddev: the watchdog device to get the remaining time from
  *	@timeleft: the time that's left
@@ -393,6 +424,12 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
 		if (err)
 			return err;
 		return put_user(val, p);
+	case WDIOC_SETPRETIMEOUT:
+		if (get_user(val, p))
+			return -EFAULT;
+		return watchdog_set_pretimeout(wdd, val);
+	case WDIOC_GETPRETIMEOUT:
+		return put_user(wdd->pretimeout, p);
 	default:
 		return -ENOTTY;
 	}
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index d74a0e9..281b949 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -25,6 +25,7 @@ struct 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.
+ * @set_pretimeout:The routine for setting the watchdog devices pretimeout.
  * @get_timeleft:The routine that get's the time that's left before a reset.
  * @ref:	The ref operation for dyn. allocated watchdog_device structs
  * @unref:	The unref operation for dyn. allocated watchdog_device structs
@@ -44,6 +45,7 @@ struct watchdog_ops {
 	int (*ping)(struct watchdog_device *);
 	unsigned int (*status)(struct watchdog_device *);
 	int (*set_timeout)(struct watchdog_device *, unsigned int);
+	int (*set_pretimeout)(struct watchdog_device *, unsigned int);
 	unsigned int (*get_timeleft)(struct watchdog_device *);
 	void (*ref)(struct watchdog_device *);
 	void (*unref)(struct watchdog_device *);
@@ -60,6 +62,7 @@ struct watchdog_ops {
  * @ops:	Pointer to the list of watchdog operations.
  * @bootstatus:	Status of the watchdog device at boot.
  * @timeout:	The watchdog devices timeout value.
+ * @pretimeout: The watchdog devices pre_timeout value.
  * @min_timeout:The watchdog devices minimum timeout value.
  * @max_timeout:The watchdog devices maximum timeout value.
  * @driver-data:Pointer to the drivers private data.
@@ -86,6 +89,7 @@ struct watchdog_device {
 	const struct watchdog_ops *ops;
 	unsigned int bootstatus;
 	unsigned int timeout;
+	unsigned int pretimeout;
 	unsigned int min_timeout;
 	unsigned int max_timeout;
 	void *driver_data;
@@ -123,6 +127,13 @@ static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigne
 		(t < wdd->min_timeout || t > wdd->max_timeout));
 }
 
+/* Use the following function to check if a pretimeout value is invalid */
+static inline bool watchdog_pretimeout_invalid(struct watchdog_device *wdd,
+					       unsigned int t)
+{
+	return wdd->timeout && t >= wdd->timeout;
+}
+
 /* Use the following functions to manipulate watchdog driver specific data */
 static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data)
 {
-- 
1.9.1

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