bcm2835_wdt: support for the BCM2835/2836 watchdog

Signed-off-by: Paolo Pisati <p.pisati@gmail.com>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 2034e3c..bdaf5d4 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1,5 +1,17 @@
 menu "Watchdog Timer Support"
 
+config HW_WATCHDOG
+	bool
+
+config BCM2835_WDT
+	bool "Enable BCM2835/2836 watchdog driver"
+	select HW_WATCHDOG
+	help
+	  Say Y here to enable the BCM2835/2836 watchdog
+
+	  This provides basic infrastructure to support BCM2835/2836 watchdog
+	  hardware, with a max timeout of ~15secs.
+
 config ULP_WATCHDOG
 	bool "i.MX7ULP watchdog"
 	help
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index dfc7fbd..8378601 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -18,3 +18,4 @@
 obj-$(CONFIG_WDT) += wdt-uclass.o
 obj-$(CONFIG_WDT_SANDBOX) += sandbox_wdt.o
 obj-$(CONFIG_WDT_ASPEED) += ast_wdt.o
+obj-$(CONFIG_BCM2835_WDT)       += bcm2835_wdt.o
diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c
new file mode 100644
index 0000000..6f753ae
--- /dev/null
+++ b/drivers/watchdog/bcm2835_wdt.c
@@ -0,0 +1,35 @@
+/*
+ * Watchdog driver for Broadcom BCM2835
+ *
+ * Copyright (C) 2017 Paolo Pisati <p.pisati@gmail.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+#include <common.h>
+#include <efi_loader.h>
+#include <asm/io.h>
+#include <asm/arch/wdog.h>
+
+#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
+#define MAX_TIMEOUT   0xf /* ~15s */
+
+static __efi_runtime_data bool enabled = true;
+
+extern void reset_cpu(ulong ticks);
+
+void hw_watchdog_reset(void)
+{
+	if (enabled)
+		reset_cpu(SECS_TO_WDOG_TICKS(MAX_TIMEOUT));
+}
+
+void hw_watchdog_init(void)
+{
+	hw_watchdog_reset();
+}
+
+void __efi_runtime hw_watchdog_disable(void)
+{
+	enabled = false;
+}