watchdog: Automatically register device with sysreset

Add an option to automatically register watchdog devices with the
wdt_reboot driver for use with sysreset. This allows sysreset to be a
drop-in replacement for platform-specific watchdog reset code, without
needing any device tree changes.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Stefan Roese <sr@denx.de>

drivers/sysreset/Kconfig

@@ -131,6 +131,13 @@ config SYSRESET_WATCHDOG
 	help
 	  Reboot support for generic watchdog reset.
 
+config SYSRESET_WATCHDOG_AUTO
+	bool "Automatically register first watchdog with sysreset"
+	depends on SYSRESET_WATCHDOG
+	help
+	  If enabled, the first watchdog (as selected by the watchdog uclass)
+	  will automatically be registered with the watchdog reboot driver.
+
 config SYSRESET_RESETCTL
 	bool "Enable support for reset controller reboot driver"
 	select DM_RESET

drivers/sysreset/sysreset_watchdog.c

@@ -5,7 +5,9 @@
 
 #include <common.h>
 #include <dm.h>
+#include <dm/device-internal.h>
 #include <errno.h>
+#include <malloc.h>
 #include <sysreset.h>
 #include <wdt.h>
 
@@ -57,3 +59,25 @@ U_BOOT_DRIVER(wdt_reboot) = {
 	.plat_auto	= sizeof(struct wdt_reboot_plat),
 	.ops = &wdt_reboot_ops,
 };
+
+#if IS_ENABLED(CONFIG_SYSRESET_WATCHDOG_AUTO)
+int sysreset_register_wdt(struct udevice *dev)
+{
+	struct wdt_reboot_plat *plat = malloc(sizeof(*plat));
+	int ret;
+
+	if (!plat)
+		return -ENOMEM;
+
+	plat->wdt = dev;
+
+	ret = device_bind(dev, DM_DRIVER_GET(wdt_reboot),
+			  dev->name, plat, ofnode_null(), NULL);
+	if (ret) {
+		free(plat);
+		return ret;
+	}
+
+	return 0;
+}
+#endif

drivers/watchdog/wdt-uclass.c

@@ -10,6 +10,7 @@
 #include <errno.h>
 #include <hang.h>
 #include <log.h>
+#include <sysreset.h>
 #include <time.h>
 #include <wdt.h>
 #include <asm/global_data.h>
@@ -44,6 +45,13 @@ static void init_watchdog_dev(struct udevice *dev)
 
 	priv = dev_get_uclass_priv(dev);
 
+	if (IS_ENABLED(CONFIG_SYSRESET_WATCHDOG_AUTO)) {
+		ret = sysreset_register_wdt(dev);
+		if (ret)
+			printf("WDT:   Failed to register %s for sysreset\n",
+			       dev->name);
+	}
+
 	if (!IS_ENABLED(CONFIG_WATCHDOG_AUTOSTART)) {
 		printf("WDT:   Not starting %s\n", dev->name);
 		return;

include/sysreset.h

@@ -133,4 +133,14 @@ void sysreset_walk_halt(enum sysreset_t type);
  */
 void reset_cpu(void);
 
+/**
+ * sysreset_register_wdt() - register a watchdog for use with sysreset
+ *
+ * This registers the given watchdog timer to be used to reset the system.
+ *
+ * @dev:	WDT device
+ * @return:	0 if OK, -errno if error
+ */
+int sysreset_register_wdt(struct udevice *dev);
+
 #endif