watchdog: Implement generic watchdog_reset() version

This patch tries to implement a generic watchdog_reset() function that
can be used by all boards that want to service the watchdog device in
U-Boot. This watchdog servicing is enabled via CONFIG_WATCHDOG.

Without this approach, new boards or platforms needed to implement a
board specific version of this functionality, mostly copy'ing the same
code over and over again into their board or platforms code base.

With this new generic function, the scattered other functions are now
removed to be replaced by the generic one. The new version also enables
the configuration of the watchdog timeout via the DT "timeout-sec"
property (if enabled via CONFIG_OF_CONTROL).

This patch also adds a new flag to the GD flags, to flag that the
watchdog is ready to use and adds the pointer to the watchdog device
to the GD. This enables us to remove the global "watchdog_dev"
variable, which was prone to cause problems because of its potentially
very early use in watchdog_reset(), even before the BSS is cleared.

Signed-off-by: Stefan Roese <[email protected]>
Cc: Heiko Schocher <[email protected]>
Cc: Tom Rini <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: "Marek Behún" <[email protected]>
Cc: Daniel Schwierzeck <[email protected]>
Cc: Maxim Sloyko <[email protected]>
Cc: Erik van Luijk <[email protected]>
Cc: Ryder Lee <[email protected]>
Cc: Weijie Gao <[email protected]>
Cc: Simon Glass <[email protected]>
Cc: "Álvaro Fernández Rojas" <[email protected]>
Cc: Philippe Reynes <[email protected]>
Cc: Christophe Leroy <[email protected]>
Reviewed-by: Michal Simek <[email protected]>
Tested-by: Michal Simek <[email protected]> (on zcu100)

2 files changed, 27 insertions, 0 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 9d7f503b698..aa8e7255735 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -51,6 +51,7 @@ config ULP_WATCHDOG
 config WDT
 	bool "Enable driver model for watchdog timer drivers"
 	depends on DM
+	imply WATCHDOG
 	help
 	  Enable driver model for watchdog timer. At the moment the API
 	  is very simple and only supports four operations:
diff --git a/drivers/watchdog/wdt-uclass.c b/drivers/watchdog/wdt-uclass.c
index 23b7e3360d3..bbfac4f0f9b 100644
--- a/drivers/watchdog/wdt-uclass.c
+++ b/drivers/watchdog/wdt-uclass.c
@@ -10,6 +10,8 @@
 #include <dm/device-internal.h>
 #include <dm/lists.h>
 
+DECLARE_GLOBAL_DATA_PTR;
+
 int wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
 {
 	const struct wdt_ops *ops = device_get_ops(dev);
@@ -63,6 +65,30 @@ int wdt_expire_now(struct udevice *dev, ulong flags)
 	return ret;
 }
 
+#if defined(CONFIG_WATCHDOG)
+/*
+ * Called by macro WATCHDOG_RESET. This function be called *very* early,
+ * so we need to make sure, that the watchdog driver is ready before using
+ * it in this function.
+ */
+void watchdog_reset(void)
+{
+	static ulong next_reset;
+	ulong now;
+
+	/* Exit if GD is not ready or watchdog is not initialized yet */
+	if (!gd || !(gd->flags & GD_FLG_WDT_READY))
+		return;
+
+	/* Do not reset the watchdog too often */
+	now = get_timer(0);
+	if (now > next_reset) {
+		next_reset = now + 1000;	/* reset every 1000ms */
+		wdt_reset(gd->watchdog_dev);
+	}
+}
+#endif
+
 static int wdt_post_bind(struct udevice *dev)
 {
 #if defined(CONFIG_NEEDS_MANUAL_RELOC)