arm: mvebu: x530: Enable watchdog in SPL and U-Boot

Enable the hardware watchdog to guard against system lock ups when
running in the SPL or U-Boot. Stop the watchdog just before booting so
that the OS can re-enable it if needed.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>

arch/arm/dts/armada-385-atl-x530-u-boot.dtsi

@@ -11,3 +11,7 @@
 &uart0 {
 	u-boot,dm-pre-reloc;
 };
+
+&watchdog {
+	u-boot,dm-pre-reloc;
+};

board/alliedtelesis/x530/x530.c

@@ -7,6 +7,7 @@
 #include <command.h>
 #include <dm.h>
 #include <i2c.h>
+#include <wdt.h>
 #include <asm/gpio.h>
 #include <linux/mbus.h>
 #include <linux/io.h>
@@ -24,6 +25,10 @@ DECLARE_GLOBAL_DATA_PTR;
 #define CONFIG_NVS_LOCATION		0xf4800000
 #define CONFIG_NVS_SIZE			(512 << 10)
 
+#ifdef CONFIG_WATCHDOG
+static struct udevice *watchdog_dev;
+#endif
+
 static struct serdes_map board_serdes_map[] = {
 	{PEX0, SERDES_SPEED_5_GBPS, PEX_ROOT_COMPLEX_X1, 0, 0},
 	{DEFAULT_SERDES, SERDES_SPEED_5_GBPS, SERDES_DEFAULT_MODE, 0, 0},
@@ -75,6 +80,10 @@ struct mv_ddr_topology_map *mv_ddr_topology_map_get(void)
 
 int board_early_init_f(void)
 {
+#ifdef CONFIG_WATCHDOG
+	watchdog_dev = NULL;
+#endif
+
 	/* Configure MPP */
 	writel(0x00001111, MVEBU_MPP_BASE + 0x00);
 	writel(0x00000000, MVEBU_MPP_BASE + 0x04);
@@ -88,6 +97,17 @@ int board_early_init_f(void)
 	return 0;
 }
 
+void spl_board_init(void)
+{
+#ifdef CONFIG_WATCHDOG
+	int ret;
+
+	ret = uclass_get_device(UCLASS_WDT, 0, &watchdog_dev);
+	if (!ret)
+		wdt_start(watchdog_dev, 120000, 0);
+#endif
+}
+
 int board_init(void)
 {
 	/* address of boot parameters */
@@ -100,9 +120,37 @@ int board_init(void)
 	/* DEV_READYn is not needed for NVS, ignore it when accessing CS1 */
 	writel(0x00004001, MVEBU_DEV_BUS_BASE + 0xc8);
 
+	spl_board_init();
+
 	return 0;
 }
 
+void arch_preboot_os(void)
+{
+#ifdef CONFIG_WATCHDOG
+	wdt_stop(watchdog_dev);
+#endif
+}
+
+#ifdef CONFIG_WATCHDOG
+void watchdog_reset(void)
+{
+	static ulong next_reset = 0;
+	ulong now;
+
+	if (!watchdog_dev)
+		return;
+
+	now = timer_get_us();
+
+	/* Do not reset the watchdog too often */
+	if (now > next_reset) {
+		wdt_reset(watchdog_dev);
+		next_reset = now + 1000;
+	}
+}
+#endif
+
 static int led_7seg_init(unsigned int segments)
 {
 	int node;

configs/x530_defconfig

@@ -19,6 +19,8 @@ CONFIG_SILENT_CONSOLE=y
 CONFIG_SILENT_U_BOOT_ONLY=y
 CONFIG_SILENT_CONSOLE_UPDATE_ON_RELOC=y
 CONFIG_MISC_INIT_R=y
+CONFIG_SPL_BOARD_INIT=y
+CONFIG_SPL_WATCHDOG_SUPPORT=y
 CONFIG_CMD_MEMINFO=y
 # CONFIG_CMD_FLASH is not set
 CONFIG_CMD_GPIO=y
@@ -72,3 +74,6 @@ CONFIG_USB_STORAGE=y
 CONFIG_USB_HOST_ETHER=y
 CONFIG_USB_ETHER_ASIX=y
 CONFIG_USB_ETHER_ASIX88179=y
+CONFIG_WATCHDOG=y
+CONFIG_WDT=y
+CONFIG_WDT_ORION=y