watchdog: Add TCO support for nVidia chipsets

This driver adds support for /dev/watchdog for boards using either the MCP51 or
MCP55 chipsets.  These are also known as the nForce 430 and nForce 550.  This
driver is likely to work on other chipsets as well, though those are the only
two that have been tested.

Signed-off-by: Mike Waychison <mikew@google.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig

@@ -642,6 +642,24 @@ config PC87413_WDT
 
 	  Most people will say N.
 
+config NV_TCO
+	tristate "nVidia TCO Timer/Watchdog"
+	depends on X86 && PCI
+	---help---
+	  Hardware driver for the TCO timer built into the nVidia Hub family
+	  (such as the MCP51).  The TCO (Total Cost of Ownership) timer is a
+	  watchdog timer that will reboot the machine after its second
+	  expiration. The expiration time can be configured with the
+	  "heartbeat" parameter.
+
+	  On some motherboards the driver may fail to reset the chipset's
+	  NO_REBOOT flag which prevents the watchdog from rebooting the
+	  machine. If this is the case you will get a kernel message like
+	  "failed to reset NO_REBOOT flag, reboot disabled by hardware".
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called nv_tco.
+
 config RDC321X_WDT
 	tristate "RDC R-321x SoC watchdog"
 	depends on X86_RDC321X