Add support for gpio-poweroff (torvalds#29)

Cherry picked from Raspberry Pi kernel source. Signed-off-by: Phil Elwell <phil@raspberrypi.com> Signed-off-by: Nick Bulleid <nedbulleid@fastmail.com>
steev · Nov 23, 2024 · e80c9d3 · e80c9d3
1 parent a7c603b
commit e80c9d3
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Showing 4 changed files with 43 additions and 3 deletions.
diff --git a/Documentation/devicetree/bindings/power/reset/gpio-poweroff.txt b/Documentation/devicetree/bindings/power/reset/gpio-poweroff.txt
@@ -31,6 +31,7 @@ Optional properties:
 - inactive-delay-ms: Delay (default 100) to wait after driving gpio inactive
 - timeout-ms: Time to wait before asserting a WARN_ON(1). If nothing is
               specified, 3000 ms is used.
+- export : Export the GPIO line to the sysfs system
 
 Examples:
 

diff --git a/arch/arm64/boot/dts/amlogic/overlay/Makefile b/arch/arm64/boot/dts/amlogic/overlay/Makefile
@@ -28,7 +28,8 @@ dtbo-$(CONFIG_ARCH_MESON) += \
 	meson-g12b-spi-b-gpioh-4-5-6-7.dtbo \
 	meson-g12b-uart-ao-a-gpioao-0-1.dtbo \
 	meson-g12b-uart-ao-b-gpioao-8-9.dtbo \
-	meson-g12b-uart-ee-c-gpioh-4-5-6-7.dtbo
+	meson-g12b-uart-ee-c-gpioh-4-5-6-7.dtbo \
+	meson-g12a-gpio-poweroff.dtbo
 
 scr-$(CONFIG_ARCH_MESON) += \
 	meson-fixup.scr

diff --git a/arch/arm64/boot/dts/amlogic/overlay/meson-g12a-gpio-poweroff.dts b/arch/arm64/boot/dts/amlogic/overlay/meson-g12a-gpio-poweroff.dts
@@ -0,0 +1,22 @@
+/dts-v1/;
+/plugin/;
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/gpio/meson-g12a-gpio.h>
+
+/ {
+        compatible = "radxa,zero", "amlogic,g12a";
+
+        fragment@0 {
+                target-path = "/";
+                __overlay__ {
+			gpio-poweroff {
+		                compatible = "gpio-poweroff";
+                                /* Sets poweroff pin to GPIOAO_9 as an example. Modify as needed. */
+                                gpios = <&gpio_ao GPIOAO_9 GPIO_ACTIVE_LOW>;
+		                timeout-ms = <20000>;
+				force;
+		        };
+		};
+	};
+};
diff --git a/drivers/power/reset/gpio-poweroff.c b/drivers/power/reset/gpio-poweroff.c
@@ -24,6 +24,7 @@ static struct gpio_desc *reset_gpio;
 static u32 timeout = DEFAULT_TIMEOUT_MS;
 static u32 active_delay = 100;
 static u32 inactive_delay = 100;
+static void (*old_power_off)(void);
 
 static void gpio_poweroff_do_poweroff(void)
 {
@@ -43,16 +44,22 @@ static void gpio_poweroff_do_poweroff(void)
 	/* give it some time */
 	mdelay(timeout);
 
+	if (old_power_off)
+		old_power_off();
+
 	WARN_ON(1);
 }
 
 static int gpio_poweroff_probe(struct platform_device *pdev)
 {
 	bool input = false;
 	enum gpiod_flags flags;
+	bool force = false;
+	bool export = false;
 
 	/* If a pm_power_off function has already been added, leave it alone */
-	if (pm_power_off != NULL) {
+	force = of_property_read_bool(pdev->dev.of_node, "force");
+	if (!force && (pm_power_off != NULL)) {
 		dev_err(&pdev->dev,
 			"%s: pm_power_off function already registered\n",
 		       __func__);
@@ -74,14 +81,23 @@ static int gpio_poweroff_probe(struct platform_device *pdev)
 	if (IS_ERR(reset_gpio))
 		return PTR_ERR(reset_gpio);
 
+	export = of_property_read_bool(pdev->dev.of_node, "export");
+	if (export) {
+		gpiod_export(reset_gpio, false);
+		gpiod_export_link(&pdev->dev, "poweroff-gpio", reset_gpio);
+	}
+
+	old_power_off = pm_power_off;
 	pm_power_off = &gpio_poweroff_do_poweroff;
 	return 0;
 }
 
 static int gpio_poweroff_remove(struct platform_device *pdev)
 {
 	if (pm_power_off == &gpio_poweroff_do_poweroff)
-		pm_power_off = NULL;
+		pm_power_off = old_power_off;
+
+	gpiod_unexport(reset_gpio);
 
 	return 0;
 }