watchdog: atcwdt200: Add driver for Andes ATCWDT200

Add support for the Andes ATCWDT200 watchdog timer. The driver implements
programmable reset and interrupt timers, and includes automatic detection
of the supported IntTime bit-width.

Integrated with the Linux watchdog framework, it supports basic operations
including start, stop, ping, timeout configuration, and system reset via
the restart handler.

Signed-off-by: CL Wang <cl634@andestech.com>
Link: https://lore.kernel.org/r/20260115081444.2452357-3-cl634@andestech.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/watchdog/Kconfig

@@ -2119,6 +2119,15 @@ config WATCHDOG_RTAS
 
 # RISC-V Architecture
 
+config ATCWDT200_WATCHDOG
+	tristate "Andes ATCWDT200 Watchdog support"
+	depends on ARCH_ANDES || COMPILE_TEST
+	help
+	  Driver for the Andes ATCWDT200 watchdog timer. It provides access to
+	  programmable reset and interrupt counters with clock-source dependent
+	  timing. The driver automatically detects the supported IntTime bit-width
+	  and is fully integrated with the Linux Watchdog Framework.
+
 config STARFIVE_WATCHDOG
 	tristate "StarFive Watchdog support"
 	depends on ARCH_STARFIVE || COMPILE_TEST

drivers/watchdog/Makefile

@@ -198,6 +198,7 @@ obj-$(CONFIG_PSERIES_WDT) += pseries-wdt.o
 obj-$(CONFIG_WATCHDOG_RTAS) += wdrtas.o
 
 # RISC-V Architecture
+obj-$(CONFIG_ATCWDT200_WATCHDOG) += atcwdt200_wdt.o
 obj-$(CONFIG_STARFIVE_WATCHDOG) += starfive-wdt.o
 
 # S390 Architecture