watchdog: add pretimeout support to the core

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

Signed-off-by: Robin Gong <b38343@freescale.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
[vzapolskiy: added conditional pretimeout sysfs attribute visibility]
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index 7f31125..3402dca 100644 (file)
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -50,6 +50,7 @@ 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;
        unsigned int min_hw_heartbeat_ms;
@@ -77,6 +78,7 @@ It contains following fields:
 * timeout: the watchdog timer's timeout value (in seconds).
   This is the time after which the system will reboot if user space does
   not send a heartbeat request if WDOG_ACTIVE is set.
+* pretimeout: the watchdog timer's pretimeout value (in seconds).
 * min_timeout: the watchdog timer's minimum timeout value (in seconds).
   If set, the minimum configurable value for 'timeout'.
 * max_timeout: the watchdog timer's maximum timeout value (in seconds),
@@ -121,6 +123,7 @@ 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 *);
        int (*restart)(struct watchdog_device *);
        void (*ref)(struct watchdog_device *) __deprecated;
@@ -188,6 +191,23 @@ they are supported. These optional routines/operations are:
   If set_timeout is not provided but, WDIOF_SETTIMEOUT is set, the watchdog
   infrastructure updates the timeout value of the watchdog_device internally
   to the requested value.
+  If the pretimeout feature is used (WDIOF_PRETIMEOUT), then set_timeout must
+  also take care of checking if pretimeout is still valid and set up the timer
+  accordingly. This can't be done in the core without races, so it is the
+  duty of the driver.
+* set_pretimeout: this routine checks and changes the pretimeout value of
+  the watchdog. It is optional because not all watchdogs support pretimeout
+  notification. The timeout value is not an absolute time, but the number of
+  seconds before the actual timeout would happen. It returns 0 on success,
+  -EINVAL for "parameter out of range" and -EIO for "could not write value to
+  the watchdog". A value of 0 disables pretimeout notification.
+  (Note: the WDIOF_PRETIMEOUT needs to be set in the options field of the
+  watchdog's info structure).
+  If the watchdog driver does not have to perform any action but setting the
+  watchdog_device.pretimeout, this callback can be omitted. That means if
+  set_pretimeout is not provided but WDIOF_PRETIMEOUT is set, the watchdog
+  infrastructure updates the pretimeout value of the watchdog_device internally
+  to the requested value.
 * get_timeleft: this routines returns the time that's left before a reset.
 * restart: this routine restarts the machine. It returns 0 on success or a
   negative errno code for failure.

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 040bf83..4b381a6 100644 (file)
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -335,16 +335,45 @@ static int watchdog_set_timeout(struct watchdog_device *wdd,
        if (watchdog_timeout_invalid(wdd, timeout))
                return -EINVAL;
 
-       if (wdd->ops->set_timeout)
+       if (wdd->ops->set_timeout) {
                err = wdd->ops->set_timeout(wdd, timeout);
-       else
+       } else {
                wdd->timeout = timeout;
+               /* Disable pretimeout if it doesn't fit the new timeout */
+               if (wdd->pretimeout >= wdd->timeout)
+                       wdd->pretimeout = 0;
+       }
 
        watchdog_update_worker(wdd);
 
        return err;
 }
 
+/*
+ *     watchdog_set_pretimeout: set the watchdog timer pretimeout
+ *     @wdd: the watchdog device to set the timeout for
+ *     @timeout: pretimeout to set in seconds
+ */
+
+static int watchdog_set_pretimeout(struct watchdog_device *wdd,
+                                  unsigned int timeout)
+{
+       int err = 0;
+
+       if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+               return -EOPNOTSUPP;
+
+       if (watchdog_pretimeout_invalid(wdd, timeout))
+               return -EINVAL;
+
+       if (wdd->ops->set_pretimeout)
+               err = wdd->ops->set_pretimeout(wdd, timeout);
+       else
+               wdd->pretimeout = timeout;
+
+       return err;
+}
+
 /*
  *     watchdog_get_timeleft: wrapper to get the time left before a reboot
  *     @wdd: the watchdog device to get the remaining time from
@@ -429,6 +458,15 @@ static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(timeout);
 
+static ssize_t pretimeout_show(struct device *dev,
+                              struct device_attribute *attr, char *buf)
+{
+       struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+       return sprintf(buf, "%u\n", wdd->pretimeout);
+}
+static DEVICE_ATTR_RO(pretimeout);
+
 static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
                                char *buf)
 {
@@ -459,6 +497,9 @@ static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
 
        if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
                mode = 0;
+       else if (attr == &dev_attr_pretimeout.attr &&
+                !(wdd->info->options & WDIOF_PRETIMEOUT))
+               mode = 0;
 
        return mode;
 }
@@ -466,6 +507,7 @@ static struct attribute *wdt_attrs[] = {
        &dev_attr_state.attr,
        &dev_attr_identity.attr,
        &dev_attr_timeout.attr,
+       &dev_attr_pretimeout.attr,
        &dev_attr_timeleft.attr,
        &dev_attr_bootstatus.attr,
        &dev_attr_status.attr,
@@ -646,6 +688,16 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
                        break;
                err = put_user(val, p);
                break;
+       case WDIOC_SETPRETIMEOUT:
+               if (get_user(val, p)) {
+                       err = -EFAULT;
+                       break;
+               }
+               err = watchdog_set_pretimeout(wdd, val);
+               break;
+       case WDIOC_GETPRETIMEOUT:
+               err = put_user(wdd->pretimeout, p);
+               break;
        default:
                err = -ENOTTY;
                break;

diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 7047bc7..4035df7 100644 (file)
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -28,6 +28,7 @@ struct watchdog_core_data;
  * @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 (in seconds).
+ * @set_pretimeout:The routine for setting the watchdog devices pretimeout.
  * @get_timeleft:The routine that gets the time left before a reset (in seconds).
  * @restart:   The routine for restarting the machine.
  * @ioctl:     The routines that handles extra ioctl calls.
@@ -46,6 +47,7 @@ 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 *);
        int (*restart)(struct watchdog_device *, unsigned long, void *);
        long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
@@ -61,6 +63,7 @@ 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 (in seconds).
+ * @pretimeout: The watchdog devices pre_timeout value.
  * @min_timeout:The watchdog devices minimum timeout value (in seconds).
  * @max_timeout:The watchdog devices maximum timeout value (in seconds)
  *             as configurable from user space. Only relevant if
@@ -96,6 +99,7 @@ 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;
        unsigned int min_hw_heartbeat_ms;
@@ -163,6 +167,13 @@ static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigne
                 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 t && 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)
 {