[PATCH v4] arm64: dts: mt8173-elm: Switch to SMC watchdog

[Pin-yen Lin <treapking@chromium.org>]

Switch to SMC watchdog because we need direct control of HW watchdog
registers from kernel. The corresponding firmware was uploaded in
https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/3405.

Signed-off-by: Pin-yen Lin <treapking@chromium.org>
---

Changes in v4:
- Rename the watchdog node (smc_watchdog -> watchdog)
- Correct the patch summary (mt8173-oak -> mt8173-elm)

Changes in v3:
- Remove /delete-node/ and create a new node for SMC watchdog.

Changes in v2:
- Move the modifications to mt8173-elm.dtsi and add some comments.

 arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi b/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi
index e21feb85d822..421bb2945135 100644
--- a/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi
@@ -161,6 +161,19 @@ hdmi_connector_in: endpoint {
 			};
 		};
 	};
+
+
+	watchdog {
+		compatible = "arm,smc-wdt";
+	};
+};
+
+/*
+ * Disable the original MMIO watch dog and switch to the SMC watchdog, which
+ * operates on the same MMIO.
+ */
+&watchdog {
+	status = "disabled";
 };
 
 &mfg_async {
-- 
2.37.1.455.g008518b4e5-goog