watchdog: WatchDog Timer Driver Core - Add basic framework

The WatchDog Timer Driver Core is a framework
that contains the common code for all watchdog-driver's.
It also introduces a watchdog device structure and the
operations that go with it.

This is the introduction of this framework. This part
supports the minimal watchdog userspace API (or with
other words: the functionality to use /dev/watchdog's
open, release and write functionality as defined in
the simplest watchdog API). Extra functionality will
follow in the next set of patches.

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>

1 files changed, 61 insertions, 0 deletions

diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 011bcfeb9f09..5ab31bfd2906 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -59,6 +59,67 @@ struct watchdog_info {
 #define WATCHDOG_NOWAYOUT       0
 #endif
 
+struct watchdog_ops;
+struct watchdog_device;
+
+/** struct watchdog_ops - The watchdog-devices operations
+ *
+ * @owner:      The module owner.
+ * @start:      The routine for starting the watchdog device.
+ * @stop:       The routine for stopping the watchdog device.
+ * @ping:       The routine that sends a keepalive ping to the watchdog device.
+ *
+ * The watchdog_ops structure contains a list of low-level operations
+ * that control a watchdog device. It also contains the module that owns
+ * these operations. The start and stop function are mandatory, all other
+ * functions are optonal.
+ */
+struct watchdog_ops {
+        struct module *owner;
+        /* mandatory operations */
+        int (*start)(struct watchdog_device *);
+        int (*stop)(struct watchdog_device *);
+        /* optional operations */
+        int (*ping)(struct watchdog_device *);
+};
+
+/** struct watchdog_device - The structure that defines a watchdog device
+ *
+ * @info:       Pointer to a watchdog_info structure.
+ * @ops:        Pointer to the list of watchdog operations.
+ * @driver-data:Pointer to the drivers private data.
+ * @status:     Field that contains the devices internal status bits.
+ *
+ * The watchdog_device structure contains all information about a
+ * watchdog timer device.
+ *
+ * The driver-data field may not be accessed directly. It must be accessed
+ * via the watchdog_set_drvdata and watchdog_get_drvdata helpers.
+ */
+struct watchdog_device {
+        const struct watchdog_info *info;
+        const struct watchdog_ops *ops;
+        void *driver_data;
+        unsigned long status;
+/* Bit numbers for status flags */
+#define WDOG_DEV_OPEN           1       /* Opened via /dev/watchdog ? */
+};
+
+/* Use the following functions to manipulate watchdog driver specific data */
+static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data)
+{
+        wdd->driver_data = data;
+}
+
+static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
+{
+        return wdd->driver_data;
+}
+
+/* drivers/watchdog/core/watchdog_core.c */
+extern int watchdog_register_device(struct watchdog_device *);
+extern void watchdog_unregister_device(struct watchdog_device *);
+
 #endif  /* __KERNEL__ */
 
 #endif  /* ifndef _LINUX_WATCHDOG_H */