hwmon: (sch56xx) Add support for the integrated watchdog (v2)

Add support for the watchdog integrated into the SMSC SCH5627 and
SCH5636 superio-s. Since the watchdog is part of the hwmon logical device
and thus shares ioports with it, the watchdog driver is integrated into the
existing hwmon drivers for these.

Note that this version of the watchdog support for sch56xx superio-s
implements the watchdog chardev interface itself, rather then relying on
the recently added watchdog core / watchdog_dev. This is done because
currently some needed functionality is missing from watchdog_dev, as soon
as this functionality is added (which is being discussed on the
linux-watchdog mailinglist), I'll convert this driver over to using
watchdog_dev.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
[guenter.roeck@ericsson.com: Added missing linux/slab.h include]
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
diff --git a/Documentation/hwmon/sch5627 b/Documentation/hwmon/sch5627
index 446a054..0551d26 100644
--- a/Documentation/hwmon/sch5627
+++ b/Documentation/hwmon/sch5627
@@ -16,6 +16,11 @@
 SMSC SCH5627 Super I/O chips include complete hardware monitoring
 capabilities. They can monitor up to 5 voltages, 4 fans and 8 temperatures.
 
+The SMSC SCH5627 hardware monitoring part also contains an integrated
+watchdog. In order for this watchdog to function some motherboard specific
+initialization most be done by the BIOS, so if the watchdog is not enabled
+by the BIOS the sch5627 driver will not register a watchdog device.
+
 The hardware monitoring part of the SMSC SCH5627 is accessed by talking
 through an embedded microcontroller. An application note describing the
 protocol for communicating with the microcontroller is available upon