watchdog: Add support for Armada 37xx CPU watchdog

This adds support for the CPU watchdog found on Marvell Armada 37xx
SoCs.

There are 4 counters which can be set as CPU watchdog counters.
This driver uses the second counter (ID 1, counting from 0) as watchdog
counter, and first counter (ID 0) to implement pinging on the second
counter without the need to disable it.

Since counters IDs 2 and 3 are enabled already before even U-Boot
starts, this driver does not use them at all, for example by adding a
device tree property for counter selection.
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/Kconfig

@@ -273,6 +273,17 @@ config ARM_SBSA_WATCHDOG
 	  To compile this driver as module, choose M here: The module
 	  will be called sbsa_gwdt.
 
+config ARMADA_37XX_WATCHDOG
+	tristate "Armada 37xx watchdog"
+	depends on ARCH_MVEBU || COMPILE_TEST
+	select MFD_SYSCON
+	select WATCHDOG_CORE
+	help
+	   Say Y here to include support for the watchdog timer found on
+	   Marvell Armada 37xx SoCs.
+	   To compile this driver as a module, choose M here: the
+	   module will be called armada_37xx_wdt.
+
 config ASM9260_WATCHDOG
 	tristate "Alphascale ASM9260 watchdog"
 	depends on MACH_ASM9260 || COMPILE_TEST

drivers/watchdog/Makefile

@@ -38,6 +38,7 @@ obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
 # ARM Architecture
 obj-$(CONFIG_ARM_SP805_WATCHDOG) += sp805_wdt.o
 obj-$(CONFIG_ARM_SBSA_WATCHDOG) += sbsa_gwdt.o
+obj-$(CONFIG_ARMADA_37XX_WATCHDOG) += armada_37xx_wdt.o
 obj-$(CONFIG_ASM9260_WATCHDOG) += asm9260_wdt.o
 obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
 obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o