[PATCH 3/4] watchdog: Allow to use CONFIG_WDT without starting watchdog

[Pali Rohár]

In some cases it is useful to compile support for U-Boot command 'wdt'
without starting HW watchdog in early U-Boot phase. For example when user
want to start watchdog only on demand by some boot script.

This change adds a new compile option WATCHDOG_AUTOSTART to control whether
U-Boot should automatically start watchdog during init phase or not.

This option is enabled by default as it was was default behavior prior
introducing this new change. When compiling U-Boot users can decide to turn
this option off.

Signed-off-by: Pali Rohár <pali at kernel.org>
---
 drivers/watchdog/Kconfig      | 13 +++++++++++++
 drivers/watchdog/wdt-uclass.c |  7 +++++++
 2 files changed, 20 insertions(+)

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 602ccbe41c00..aa76a8f2d239 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -9,6 +9,19 @@ config WATCHDOG
 	  this option if you want to service enabled watchdog by U-Boot. Disable
 	  this option if you want U-Boot to start watchdog but never service it.
 
+config WATCHDOG_AUTOSTART
+	bool "Automatically start watchdog timer"
+	depends on WDT
+	default y
+	help
+	  Automatically start watchdog timer and start servicing it during
+	  init phase. Enabled by default. Disable this option if you want
+	  to compile U-Boot with CONFIG_WDT support but do not want to
+	  activate watchdog, like when CONFIG_WDT option is disabled. You
+	  would be able to start watchdog manually by 'wdt' command. Useful
+	  when you want to have support for 'wdt' command but do not want
+	  to have watchdog enabled by default.
+
 config WATCHDOG_TIMEOUT_MSECS
 	int "Watchdog timeout in msec"
 	default 128000 if ARCH_MX25 || ARCH_MX31 || ARCH_MX5 || ARCH_MX6
diff --git a/drivers/watchdog/wdt-uclass.c b/drivers/watchdog/wdt-uclass.c
index 7500b3ed90e3..00a408bf5cc5 100644
--- a/drivers/watchdog/wdt-uclass.c
+++ b/drivers/watchdog/wdt-uclass.c
@@ -27,7 +27,9 @@ static ulong reset_period = 1000;
 int initr_watchdog(void)
 {
 	u32 timeout = WATCHDOG_TIMEOUT_SECS;
+#ifdef CONFIG_WATCHDOG_AUTOSTART
 	int ret;
+#endif
 
 	/*
 	 * Init watchdog: This will call the probe function of the
@@ -51,6 +53,10 @@ int initr_watchdog(void)
 						    4 * reset_period) / 4;
 	}
 
+#ifndef CONFIG_WATCHDOG_AUTOSTART
+	printf("WDT:   Not starting\n");
+	return 0;
+#else
 	ret = wdt_start(gd->watchdog_dev, timeout * 1000, 0);
 	if (ret != 0) {
 		printf("WDT:   Failed to start\n");
@@ -61,6 +67,7 @@ int initr_watchdog(void)
 	       IS_ENABLED(CONFIG_WATCHDOG) ? "" : "out", timeout);
 
 	return 0;
+#endif
 }
 
 int wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
-- 
2.20.1