[PATCH v6 4/8] Watchdog: introdouce "pretimeout" into framework

[fu.wei@linaro.org]

From: Fu Wei <fu.wei@linaro.org>

Also update Documentation/watchdog/watchdog-kernel-api.txt to
introduce:
(1)the new elements in the watchdog_device and watchdog_ops struct;
(2)the new API "watchdog_init_timeouts"

Reasons:
(1)kernel already has two watchdog drivers are using "pretimeout":
	drivers/char/ipmi/ipmi_watchdog.c
	drivers/watchdog/kempld_wdt.c(but the definition is different)
(2)some other drivers are going to use this: ARM SBSA Generic Watchdog

Signed-off-by: Fu Wei <fu.wei@linaro.org>
---
 Documentation/watchdog/watchdog-kernel-api.txt | 47 ++++++++++--
 drivers/watchdog/watchdog_core.c               | 98 ++++++++++++++++++--------
 drivers/watchdog/watchdog_dev.c                | 53 ++++++++++++++
 include/linux/watchdog.h                       | 39 ++++++++--
 4 files changed, 200 insertions(+), 37 deletions(-)

diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index a0438f3..d1b1238 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -49,6 +49,9 @@ struct watchdog_device {
 	unsigned int timeout;
 	unsigned int min_timeout;
 	unsigned int max_timeout;
+	unsigned int pretimeout;
+	unsigned int min_pretimeout;
+	unsigned int max_pretimeout;
 	void *driver_data;
 	struct mutex lock;
 	unsigned long status;
@@ -70,6 +73,9 @@ It contains following fields:
 * timeout: the watchdog timer's timeout value (in seconds).
 * min_timeout: the watchdog timer's minimum timeout value (in seconds).
 * max_timeout: the watchdog timer's maximum timeout value (in seconds).
+* pretimeout: the watchdog timer's pretimeout value (in seconds).
+* min_pretimeout: the watchdog timer's minimum pretimeout value (in seconds).
+* max_pretimeout: the watchdog timer's maximum pretimeout 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.
@@ -92,6 +98,7 @@ 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 *);
@@ -153,9 +160,19 @@ they are supported. These optional routines/operations are:
   and -EIO for "could not write value to the watchdog". On success this
   routine should set the timeout value of the watchdog_device to the
   achieved timeout value (which may be different from the requested one
-  because the watchdog does not necessarily has a 1 second resolution).
+  because the watchdog does not necessarily has a 1 second resolution;
+  If the driver supports pretimeout, then the timeout value must be greater
+  than that).
   (Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
   watchdog's info structure).
+* set_pretimeout: this routine checks and changes the pretimeout 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 this
+  routine should set the pretimeout value of the watchdog_device to the
+  achieved pretimeout value (which may be different from the requested one
+  because the watchdog does not necessarily has a 1 second resolution).
+  (Note: the WDIOF_PRETIMEOUT 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.
@@ -219,8 +236,28 @@ extern int watchdog_init_timeout(struct watchdog_device *wdd,
                                   unsigned int timeout_parm, struct device *dev);
 
 The watchdog_init_timeout function allows you to initialize the timeout field
-using the module timeout parameter or by retrieving the timeout-sec property from
-the device tree (if the module timeout parameter is invalid). Best practice is
-to set the default timeout value as timeout value in the watchdog_device and
-then use this function to set the user "preferred" timeout value.
+using the module timeout parameter or by retrieving the first element of
+the timeout-sec property from the device tree (if the module timeout parameter
+is invalid). Best practice is to set the default timeout value as timeout value
+in the watchdog_device and then use this function to set the user "preferred"
+timeout value.
+This routine returns zero on success and a negative errno code for failure.
+
+Some watchdog timers have two stage of timeouts (timeout and pretimeout),
+to initialize the timeout and pretimeout fields at the same time, the following
+function can be used:
+
+int watchdog_init_timeouts(struct watchdog_device *wdd,
+                                  unsigned int pretimeout_parm,
+                                  unsigned int timeout_parm,
+                                  struct device *dev);
+
+The watchdog_init_timeouts function allows you to initialize the pretimeout and
+timeout fields using the module pretimeout and timeout parameter or by
+retrieving the elements in the timeout-sec property (the first element is for
+timeout, the second one is for pretimeout) from the device tree (if the module
+pretimeout and timeout parameter are invalid).
+Best practice is to set the default pretimeout and timeout value as pretimeout
+and timeout value in the watchdog_device and then use this function to set the
+user "preferred" pretimeout value.
 This routine returns zero on success and a negative errno code for failure.
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index cec9b55..a45e8bb 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -46,57 +46,99 @@ static struct class *watchdog_class;
 static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
 {
 	/*
-	 * Check that we have valid min and max timeout values, if
-	 * not reset them both to 0 (=not used or unknown)
+	 * Check that we have valid min and max pretimeout and timeout values,
+	 * if not, reset them all to 0 (=not used or unknown)
 	 */
-	if (wdd->min_timeout > wdd->max_timeout) {
-		pr_info("Invalid min and max timeout values, resetting to 0!\n");
+	if (wdd->min_pretimeout > wdd->max_pretimeout ||
+	    wdd->min_timeout > wdd->max_timeout ||
+	    wdd->min_timeout < wdd->min_pretimeout ||
+	    wdd->max_timeout < wdd->max_pretimeout) {
+		pr_info("Invalid min or max timeouts, resetting to 0\n");
+		wdd->min_pretimeout = 0;
+		wdd->max_pretimeout = 0;
 		wdd->min_timeout = 0;
 		wdd->max_timeout = 0;
 	}
 }
 
 /**
- * watchdog_init_timeout() - initialize the timeout field
+ * watchdog_init_timeouts() - initialize the pretimeout and timeout field
+ * @pretimeout_parm: pretimeout module parameter
  * @timeout_parm: timeout module parameter
  * @dev: Device that stores the timeout-sec property
  *
- * Initialize the timeout field of the watchdog_device struct with either the
- * timeout module parameter (if it is valid value) or the timeout-sec property
- * (only if it is a valid value and the timeout_parm is out of bounds).
- * If none of them are valid then we keep the old value (which should normally
- * be the default timeout value.
+ * Initialize the pretimeout and timeout field of the watchdog_device struct
+ * with both the pretimeout and timeout module parameters (if they are valid) or
+ * the timeout-sec property (only if they are valid and the pretimeout_parm or
+ * timeout_parm is out of bounds). If one of them is invalid, then we keep
+ * the old value (which should normally be the default timeout value).
  *
  * A zero is returned on success and -EINVAL for failure.
  */
-int watchdog_init_timeout(struct watchdog_device *wdd,
-				unsigned int timeout_parm, struct device *dev)
+int watchdog_init_timeouts(struct watchdog_device *wdd,
+			   unsigned int pretimeout_parm,
+			   unsigned int timeout_parm,
+			   struct device *dev)
 {
-	unsigned int t = 0;
-	int ret = 0;
+	int ret = 0, length = 0;
+	u32 timeouts[2] = {0};
+	struct property *prop;
 
 	watchdog_check_min_max_timeout(wdd);
 
-	/* try to get the timeout module parameter first */
-	if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
-		wdd->timeout = timeout_parm;
-		return ret;
-	}
-	if (timeout_parm)
+	/*
+	 * Try to get the pretimeout module parameter first.
+	 * Note: zero is a valid value for pretimeout.
+	 */
+	if (watchdog_pretimeout_invalid(wdd, pretimeout_parm))
+		ret = -EINVAL;
+
+	/*
+	 * Try to get the timeout module parameter,
+	 * if it's valid and pretimeout is valid(ret == 0),
+	 * assignment and return zero. Otherwise, try dtb.
+	 */
+	if (timeout_parm && !ret) {
+		if (!watchdog_timeout_invalid(wdd, timeout_parm)) {
+			wdd->timeout = timeout_parm;
+			wdd->pretimeout = pretimeout_parm;
+			return 0;
+		}
 		ret = -EINVAL;
+	}
 
-	/* try to get the timeout_sec property */
+	/*
+	 * Either at least one of the module parameters is invalid,
+	 * or timeout_parm is 0. Try to get the timeout_sec property.
+	 */
 	if (dev == NULL || dev->of_node == NULL)
 		return ret;
-	of_property_read_u32(dev->of_node, "timeout-sec", &t);
-	if (!watchdog_timeout_invalid(wdd, t) && t)
-		wdd->timeout = t;
-	else
-		ret = -EINVAL;
 
-	return ret;
+	prop = of_find_property(dev->of_node, "timeout-sec", &length);
+	if (prop && length > 0 && length <= sizeof(u32) * 2) {
+		of_property_read_u32_array(dev->of_node,
+					   "timeout-sec", timeouts,
+					   length / sizeof(u32));
+		if (length == sizeof(u32) * 2) {
+			if (watchdog_pretimeout_invalid(wdd, timeouts[1]))
+				return -EINVAL;
+			ret = 0;
+		} else {
+			ret = -EINVAL;
+		}
+
+		if (!watchdog_timeout_invalid(wdd, timeouts[0]) &&
+		    timeouts[0]) {
+			wdd->timeout = timeouts[0];
+			if (!ret)
+				wdd->pretimeout = timeouts[1];
+			return 0;
+		}
+	}
+
+	return -EINVAL;
 }
-EXPORT_SYMBOL_GPL(watchdog_init_timeout);
+EXPORT_SYMBOL_GPL(watchdog_init_timeouts);
 
 /**
  * watchdog_register_device() - register a watchdog device
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 6aaefba..af0777e 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -218,6 +218,38 @@ out_timeout:
 }
 
 /*
+ *	watchdog_set_pretimeout: set the watchdog timer pretimeout
+ *	@wddev: the watchdog device to set the timeout for
+ *	@pretimeout: pretimeout to set in seconds
+ */
+
+static int watchdog_set_pretimeout(struct watchdog_device *wddev,
+				   unsigned int pretimeout)
+{
+	int err;
+
+	if (!wddev->ops->set_pretimeout ||
+	    !(wddev->info->options & WDIOF_PRETIMEOUT))
+		return -EOPNOTSUPP;
+
+	if (watchdog_pretimeout_invalid(wddev, pretimeout))
+		return -EINVAL;
+
+	mutex_lock(&wddev->lock);
+
+	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+		err = -ENODEV;
+		goto out_pretimeout;
+	}
+
+	err = wddev->ops->set_pretimeout(wddev, pretimeout);
+
+out_pretimeout:
+	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
@@ -388,6 +420,27 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
 		if (wdd->timeout == 0)
 			return -EOPNOTSUPP;
 		return put_user(wdd->timeout, p);
+	case WDIOC_SETPRETIMEOUT:
+		/* check if we support the pretimeout */
+		if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+			return -EOPNOTSUPP;
+		if (get_user(val, p))
+			return -EFAULT;
+		err = watchdog_set_pretimeout(wdd, val);
+		if (err < 0)
+			return err;
+		/*
+		 * If the watchdog is active then we send a keepalive ping
+		 * to make sure that the watchdog keeps running (and if
+		 * possible that it takes the new pretimeout)
+		 */
+		watchdog_ping(wdd);
+		/* Fall */
+	case WDIOC_GETPRETIMEOUT:
+		/* check if we support the pretimeout */
+		if (wdd->info->options & WDIOF_PRETIMEOUT)
+			return put_user(wdd->pretimeout, p);
+		return -EOPNOTSUPP;
 	case WDIOC_GETTIMELEFT:
 		err = watchdog_get_timeleft(wdd, &val);
 		if (err)
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index a746bf5..47a87cb 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 value
  * @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 *);
@@ -62,6 +64,9 @@ struct watchdog_ops {
  * @timeout:	The watchdog devices timeout value.
  * @min_timeout:The watchdog devices minimum timeout value.
  * @max_timeout:The watchdog devices maximum timeout value.
+ * @pretimeout:	The watchdog devices pretimeout value.
+ * @min_pretimeout:The watchdog devices minimum pretimeout value.
+ * @max_pretimeout:The watchdog devices maximum pretimeout value.
  * @driver-data:Pointer to the drivers private data.
  * @lock:	Lock for watchdog core internal use only.
  * @status:	Field that contains the devices internal status bits.
@@ -86,6 +91,9 @@ struct watchdog_device {
 	unsigned int timeout;
 	unsigned int min_timeout;
 	unsigned int max_timeout;
+	unsigned int pretimeout;
+	unsigned int min_pretimeout;
+	unsigned int max_pretimeout;
 	void *driver_data;
 	struct mutex lock;
 	unsigned long status;
@@ -116,8 +124,22 @@ static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool noway
 /* Use the following function to check if a timeout value is invalid */
 static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigned int t)
 {
-	return ((wdd->max_timeout != 0) &&
-		(t < wdd->min_timeout || t > wdd->max_timeout));
+	return (wdd->max_timeout &&
+		(t < wdd->min_timeout || t > wdd->max_timeout)) ||
+	       (wdd->pretimeout && t <= wdd->pretimeout);
+}
+
+/*
+ * Use the following function to check if a pretimeout value is invalid.
+ * It can be "0", that means we don't use pretimeout.
+ * This function returns false, when pretimeout is 0.
+ */
+static inline bool watchdog_pretimeout_invalid(struct watchdog_device *wdd,
+					       unsigned int t)
+{
+	return t && ((wdd->max_pretimeout &&
+		      (t < wdd->min_pretimeout || t > wdd->max_pretimeout)) ||
+		     (wdd->timeout && t >= wdd->timeout));
 }
 
 /* Use the following functions to manipulate watchdog driver specific data */
@@ -132,8 +154,17 @@ static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
 }
 
 /* drivers/watchdog/watchdog_core.c */
-extern int watchdog_init_timeout(struct watchdog_device *wdd,
-				  unsigned int timeout_parm, struct device *dev);
+int watchdog_init_timeouts(struct watchdog_device *wdd,
+			   unsigned int pretimeout_parm,
+			   unsigned int timeout_parm,
+			   struct device *dev);
+static inline int watchdog_init_timeout(struct watchdog_device *wdd,
+					unsigned int timeout_parm,
+					struct device *dev)
+{
+	return watchdog_init_timeouts(wdd, 0, timeout_parm, dev);
+}
+
 extern int watchdog_register_device(struct watchdog_device *);
 extern void watchdog_unregister_device(struct watchdog_device *);
 
-- 
1.9.1