remoteproc/omap: Add watchdog functionality for remote processors

Remote processors can be stuck in a loop, and may not be recoverable
if they do not have a built-in watchdog. The watchdog implementation
for OMAP remote processors uses external gptimers that can be used
to interrupt both the Linux host as well as the remote processor.

Each remote processor is responsible for refreshing the timer during
normal behavior - during OS task scheduling or entering the idle loop
properly. During a watchdog condition (executing a tight loop causing
no scheduling), the host processor gets interrupts and schedules a
recovery for the corresponding remote processor. The remote processor
may also get interrupted to be able to print a back trace.

A menuconfig option has also been added to enable/disable the Watchdog
functionality, with the default as disabled.

Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Andrew F. Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20200324110035.29907-15-t-kristo@ti.com
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
index b52abc2..5f33358 100644
--- a/drivers/remoteproc/Kconfig
+++ b/drivers/remoteproc/Kconfig
@@ -52,6 +52,18 @@
 	  It's safe to say N here if you're not interested in multimedia
 	  offloading or just want a bare minimum kernel.
 
+config OMAP_REMOTEPROC_WATCHDOG
+	bool "OMAP remoteproc watchdog timer"
+	depends on OMAP_REMOTEPROC
+	default n
+	help
+	  Say Y here to enable watchdog timer for remote processors.
+
+	  This option controls the watchdog functionality for the remote
+	  processors in OMAP. Dedicated OMAP DMTimers are used by the remote
+	  processors and triggers the timer interrupt upon a watchdog
+	  detection.
+
 config WKUP_M3_RPROC
 	tristate "AMx3xx Wakeup M3 remoteproc support"
 	depends on SOC_AM33XX || SOC_AM43XX