mt8173: Add support for new watchdog SMC

This patch adds support for a new SMC that can be used to control the
watchdog. This allows for a cleaner separation of responsibilities where
all watchdog operations have to go through Trusted Firmware and we could
no longer have kernel and firmware poking concurrently at the same
register block.

Signed-off-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Evan Benn <evanbenn@chromium.org>
Change-Id: I4844a3559d5c956a53a74a61dd5bc2956f0cce7b
diff --git a/plat/mediatek/mt8173/drivers/wdt/wdt.h b/plat/mediatek/mt8173/drivers/wdt/wdt.h
new file mode 100644
index 0000000..7262a57
--- /dev/null
+++ b/plat/mediatek/mt8173/drivers/wdt/wdt.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2020, Google LLC. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef WDT_H
+#define WDT_H
+
+#include "stdint.h"
+
+void wdt_pet(void);
+void wdt_resume(void);
+void wdt_set_enable(int enable);
+int wdt_set_timeout(uint32_t timeout);
+uint64_t wdt_smc_handler(uint32_t x1, uint32_t x2, void *handle);
+void wdt_suspend(void);
+void wdt_trigger_reset(void);
+
+#endif /* WDT_H */