linux-kernel - [PATCH 4/7] arm64: dts: mediatek: mt6795: Add watchdog node to avoid timeouts

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Message-Id: <20220513171617.504430-5-angelogioacchino.delregno@collabora.com>
Date:   Fri, 13 May 2022 19:16:14 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     robh+dt@...nel.org
Cc:     krzysztof.kozlowski+dt@...aro.org, matthias.bgg@...il.com,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        konrad.dybcio@...ainline.org, marijn.suijten@...ainline.org,
        martin.botka@...ainline.org, ~postmarketos/upstreaming@...ts.sr.ht,
        phone-devel@...r.kernel.org, paul.bouchara@...ainline.org,
        kernel@...labora.com,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Subject: [PATCH 4/7] arm64: dts: mediatek: mt6795: Add watchdog node to avoid timeouts

At least on commercial devices like some smartphones, the bootloader
will initialize the SoC watchdog and set it to reboot the board when
it times out. The last pet that this watchdog is getting is right
before booting the kernel and left it enabled as a protection against
boot failure: this means that Linux is expected to initialize this
device and pet as soon as possible, or it will bark and reset the AP.

In order to prevent that, add the required watchdog node as default
enabled: this will have no side effects on boards that are not
performing the aforementioned watchdog setup before booting Linux.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
---
 arch/arm64/boot/dts/mediatek/mt6795.dtsi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/boot/dts/mediatek/mt6795.dtsi b/arch/arm64/boot/dts/mediatek/mt6795.dtsi
index 639104b3f693..363fa25b4edc 100644
--- a/arch/arm64/boot/dts/mediatek/mt6795.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt6795.dtsi
@@ -188,6 +188,14 @@ soc {
 		compatible = "simple-bus";
 		ranges;
 
+		watchdog: watchdog@...07000 {
+			compatible = "mediatek,mt6795-wdt";
+			reg = <0 0x10007000 0 0x100>;
+			interrupts = <GIC_SPI 128 IRQ_TYPE_LEVEL_LOW>;
+			#reset-cells = <1>;
+			timeout-sec = <20>;
+		};
+
 		sysirq: intpol-controller@...00620 {
 			compatible = "mediatek,mt6795-sysirq",
 				     "mediatek,mt6577-sysirq";
-- 
2.35.1