linux-kernel - [PATCH 2/3] arm64: dts: rockchip: expose BIOS Disable feedback pin on rk3399-puma

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Date:   Thu, 14 Dec 2023 13:28:00 +0100
From:   Vahe Grigoryan <vahe.grigoryan@...obroma-systems.com>
To:     quentin.schulz@...obroma-systems.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        heiko@...ech.de
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Vahe Grigoryan <vahe.grigoryan@...obroma-systems.com>
Subject: [PATCH 2/3] arm64: dts: rockchip: expose BIOS Disable feedback pin on rk3399-puma

The Puma SoM allows to select in hardware directly which storage
medium to try for loading the bootloader, either SPI-NOR followed
by eMMC followed by SD card, or SD card only.

This signal is exposed on the Q7 connector and allows carrierboards
to control it however they want.

This feedback pin allows to know in which state the SoM currently
is and provided the current state isn't modified until next reboot,
know from which storage medium the bootloader could be loaded from
next time.

Signed-off-by: Vahe Grigoryan <vahe.grigoryan@...obroma-systems.com>
---
 arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
index 20e3f41efe97..ea9d6ab73df5 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
@@ -119,6 +119,20 @@ &emmc_phy {
 	drive-impedance-ohm = <33>;
 };
 
+&gpio0 {
+	/*
+	 * The BIOS_DISABLE hog is a feedback pin for the actual status of the
+	 * signal. This usually represents the state of a switch on the baseboard.
+	 * The pin has a 10k pull-up resistor connected, so no pull-up setting is needed.
+	 */
+	bios-disable-hog {
+		gpios = <RK_PB0 GPIO_ACTIVE_HIGH>;
+		gpio-hog;
+		input;
+		line-name = "bios_disable";
+	};
+};
+
 &gmac {
 	assigned-clocks = <&cru SCLK_RMII_SRC>;
 	assigned-clock-parents = <&clkin_gmac>;
-- 
2.34.1