watchdog: Add multiple device support

We keep the old /dev/watchdog interface file for the first watchdog via
miscdev. This is basically a cut and paste of the relevant interface code
from the rtc driver layer tweaked for watchdog.

Revised to fix problems noted by Hans de Goede

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

1 files changed, 9 insertions, 1 deletions

diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index 25fe4304f2fc..3c85fc7dc1f1 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -1,6 +1,6 @@
 The Linux WatchDog Timer Driver Core kernel API.
 ===============================================
-Last reviewed: 16-Mar-2012
+Last reviewed: 21-May-2012
 
 Wim Van Sebroeck <wim@iguana.be>
 
@@ -39,6 +39,8 @@ watchdog_device structure.
 The watchdog device structure looks like this:
 
 struct watchdog_device {
+        int id;
+        struct cdev cdev;
         const struct watchdog_info *info;
         const struct watchdog_ops *ops;
         unsigned int bootstatus;
@@ -50,6 +52,12 @@ struct watchdog_device {
 };
 
 It contains following fields:
+* id: set by watchdog_register_device, id 0 is special. It has both a
+  /dev/watchdog0 cdev (dynamic major, minor 0) as well as the old
+  /dev/watchdog miscdev. The id is set automatically when calling
+  watchdog_register_device.
+* cdev: cdev for the dynamic /dev/watchdog<id> device nodes. This
+  field is also populated by watchdog_register_device.
 * info: a pointer to a watchdog_info structure. This structure gives some
   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.