board: sl28: disable recovery watchdog

This board has an internal watchdog which supervises the board startup.
Although, the initial state of the watchdog is configurable, it is
enabled by default. In board_late_init(), which means almost everything
worked as expected, disable the watchdog.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>

board/kontron/sl28/sl28.c

@@ -15,6 +15,7 @@
 #include <asm/arch/soc.h>
 #include <fsl_immap.h>
 #include <netdev.h>
+#include <wdt.h>
 
 #include <sl28cpld.h>
 #include <fdtdec.h>
@@ -73,6 +74,34 @@ int checkboard(void)
 	return 0;
 }
 
+static void stop_recovery_watchdog(void)
+{
+	struct udevice *dev;
+	int ret;
+
+	ret = uclass_get_device_by_driver(UCLASS_WDT,
+					  DM_DRIVER_GET(sl28cpld_wdt), &dev);
+	if (!ret)
+		wdt_stop(dev);
+}
+
+int fsl_board_late_init(void)
+{
+	/*
+	 * Usually, the after a board reset, the watchdog is enabled by
+	 * default. This is to supervise the bootloader boot-up. Therefore,
+	 * to prevent a watchdog reset if we don't actively kick it, we have
+	 * to disable it.
+	 *
+	 * If the watchdog isn't enabled at reset (which is a configuration
+	 * option) disabling it doesn't hurt either.
+	 */
+	if (!CONFIG_IS_ENABLED(WATCHDOG_AUTOSTART))
+		stop_recovery_watchdog();
+
+	return 0;
+}
+
 void detail_board_ddr_info(void)
 {
 	print_ddr_info(0);

doc/board/kontron/sl28.rst

@@ -23,17 +23,17 @@ Copy u-boot.rom to a TFTP server.
 Install the bootloader on the board
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Please note, this bootloader doesn't support the builtin watchdog (yet),
-therefore you have to disable it, see below. Otherwise you'll end up in
-the failsafe bootloader on every reset::
+To install the bootloader binary use the following command::
 
  > tftp path/to/u-boot.rom
  > sf probe 0
  > sf update $fileaddr 0x210000 $filesize
 
-The board is fully failsafe, you can't break anything. But because you've
-disabled the builtin watchdog you might have to manually enter failsafe
-mode by asserting the ``FORCE_RECOV#`` line during board reset.
+The board is fully failsafe, you can't break anything. If builtin watchdog
+is enabled, you'll automatically end up in the failsafe bootloader if
+something goes wrong. If the watchdog is disabled, you have to manually
+enter failsafe mode by asserting the ``FORCE_RECOV#`` line during board
+reset.
 
 Update image
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