watchdog: add watchdog pretimeout governor framework

The change adds a simple watchdog pretimeout framework infrastructure,
its purpose is to allow users to select a desired handling of watchdog
pretimeout events, which may be generated by some watchdog devices.

A user selects a default watchdog pretimeout governor during
compilation stage.

Watchdogs with WDIOF_PRETIMEOUT capability now have one more device
attribute in sysfs, pretimeout_governor attribute is intended to display
the selected watchdog pretimeout governor.

The framework has no impact at runtime on watchdog devices with no
WDIOF_PRETIMEOUT capability set.

Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 4035df7ec023..35a4d8185b51 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -19,6 +19,7 @@
 struct watchdog_ops;
 struct watchdog_device;
 struct watchdog_core_data;
+struct watchdog_governor;
 
 /** struct watchdog_ops - The watchdog-devices operations
  *
@@ -61,6 +62,7 @@ struct watchdog_ops {
  *              watchdog device.
  * @info:       Pointer to a watchdog_info structure.
  * @ops:        Pointer to the list of watchdog operations.
+ * @gov:        Pointer to watchdog pretimeout governor.
  * @bootstatus: Status of the watchdog device at boot.
  * @timeout:    The watchdog devices timeout value (in seconds).
  * @pretimeout: The watchdog devices pre_timeout value.
@@ -97,6 +99,7 @@ struct watchdog_device {
         const struct attribute_group **groups;
         const struct watchdog_info *info;
         const struct watchdog_ops *ops;
+        const struct watchdog_governor *gov;
         unsigned int bootstatus;
         unsigned int timeout;
         unsigned int pretimeout;
@@ -185,6 +188,16 @@ static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
         return wdd->driver_data;
 }
 
+/* Use the following functions to report watchdog pretimeout event */
+#if IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)
+void watchdog_notify_pretimeout(struct watchdog_device *wdd);
+#else
+static inline void watchdog_notify_pretimeout(struct watchdog_device *wdd)
+{
+        pr_alert("watchdog%d: pretimeout event\n", wdd->id);
+}
+#endif
+
 /* drivers/watchdog/watchdog_core.c */
 void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority);
 extern int watchdog_init_timeout(struct watchdog_device *wdd,