Patch to support gpio-poweroff on the Pi

0001-gpio-poweroff-Allow-it-to-work-on-Raspberry-Pi.patch

From ac6797373064264c76d839bfe8e9a3c68f828998 Mon Sep 17 00:00:00 2001
From: Phil Elwell <[email protected]>
Date: Thu, 25 Jun 2015 12:16:11 +0100
Subject: [PATCH] gpio-poweroff: Allow it to work on Raspberry Pi

The Raspberry Pi firmware manages the power-down and reboot
process. To do this it installs a pm_power_off handler, causing
the gpio-poweroff module to abort the probe function.

This patch introduces a "force" DT property that overrides that
behaviour, and also adds a DT overlay to enable and control it.

Note that running in an active-low configuration (DT parameter
"active_low") requires a custom dt-blob.bin and probably won't
allow a reboot without switching off, so an external inversion
of the trigger signal may be preferable.
---
 arch/arm/boot/dts/overlays/Makefile                |  1 +
 arch/arm/boot/dts/overlays/README                  | 13 +++++++++
 .../boot/dts/overlays/gpio-poweroff-overlay.dts    | 34 ++++++++++++++++++++++
 drivers/power/reset/gpio-poweroff.c                | 17 +++++++----
 4 files changed, 59 insertions(+), 6 deletions(-)
 create mode 100644 arch/arm/boot/dts/overlays/gpio-poweroff-overlay.dts

diff --git a/arch/arm/boot/dts/overlays/Makefile b/arch/arm/boot/dts/overlays/Makefile
index 19eef3c..a1397c7 100644
--- a/arch/arm/boot/dts/overlays/Makefile
+++ b/arch/arm/boot/dts/overlays/Makefile
@@ -16,6 +16,7 @@ dtb-$(RPI_DT_OVERLAYS) += ads7846-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += bmp085_i2c-sensor-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += dht11-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += enc28j60-overlay.dtb
+dtb-$(RPI_DT_OVERLAYS) += gpio-poweroff-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += hifiberry-amp-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += hifiberry-dac-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += hifiberry-dacplus-overlay.dtb
diff --git a/arch/arm/boot/dts/overlays/README b/arch/arm/boot/dts/overlays/README
index 9406cf3..0ed7094 100644
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -192,6 +192,19 @@ Params: int_pin                  GPIO used for INT (default 25)
         speed                    SPI bus speed (default 12000000)
 
 
+Name:   gpio-poweroff
+Info:   Drives a GPIO high or low on reboot
+Load:   gpio-poweroff,<param>=<val>
+Params: gpiopin                  GPIO for signalling (default 26)
+
+        active_low               Set if the power control device requires a
+                                 high->low transition to trigger a power-down.
+                                 Note that this will require the support of a
+                                 custom dt-blob.bin to prevent a power-down
+                                 during the boot process, and that a reboot
+                                 will also cause the pin to go low.
+
+
 Name:   hifiberry-amp
 Info:   Configures the HifiBerry Amp and Amp+ audio cards
 Load:   dtoverlay=hifiberry-amp
diff --git a/arch/arm/boot/dts/overlays/gpio-poweroff-overlay.dts b/arch/arm/boot/dts/overlays/gpio-poweroff-overlay.dts
new file mode 100644
index 0000000..ff8cb36
--- /dev/null
+++ b/arch/arm/boot/dts/overlays/gpio-poweroff-overlay.dts
@@ -0,0 +1,34 @@
+// Definitions for gpio-poweroff module
+/dts-v1/;
+/plugin/;
+
+/ {
+	compatible = "brcm,bcm2708";
+
+	fragment@0 {
+		target-path = "/";
+		__overlay__ {
+			power_ctrl: power_ctrl {
+				compatible = "gpio-poweroff";
+				gpios = <&gpio 26 0>;
+				force;
+			};
+		};
+	};
+
+	fragment@1 {
+		target = <&gpio>;
+		__overlay__ {
+			power_ctrl_pins: power_ctrl_pins {
+				brcm,pins = <26>;
+				brcm,function = <1>; // out
+			};
+		};
+	};
+
+	__overrides__ {
+		gpiopin =       <&power_ctrl>,"gpios:4",
+				<&power_ctrl_pins>,"brcm,pins:0";
+		active_low =    <&power_ctrl>,"gpios:8";
+	};
+};
diff --git a/drivers/power/reset/gpio-poweroff.c b/drivers/power/reset/gpio-poweroff.c
index e5332f1..a7583b5 100644
--- a/drivers/power/reset/gpio-poweroff.c
+++ b/drivers/power/reset/gpio-poweroff.c
@@ -48,13 +48,18 @@ static void gpio_poweroff_do_poweroff(void)
 static int gpio_poweroff_probe(struct platform_device *pdev)
 {
 	bool input = false;
+	bool force = false;
 
-	/* If a pm_power_off function has already been added, leave it alone */
-	if (pm_power_off != NULL) {
-		dev_err(&pdev->dev,
-			"%s: pm_power_off function already registered",
-		       __func__);
-		return -EBUSY;
+	force = of_property_read_bool(pdev->dev.of_node, "force");
+	if (!force) {
+		/* If a pm_power_off function has already been added,
+		   leave it alone */
+		if (pm_power_off != NULL) {
+			dev_err(&pdev->dev,
+				"%s: pm_power_off function already registered",
+				__func__);
+			return -EBUSY;
+		}
 	}
 
 	reset_gpio = devm_gpiod_get(&pdev->dev, NULL);
-- 
1.9.1

Has this been submitted to the Rasp PI kernel?
I was looking to use this on The Plum Geek Spirit Rover Robot, but would need it in the "standard kernel". The reason being is providing a 'custom' kernel for the robot would be a logistical nightmare. I feel that for some in the user community for the robot this would be a challenge.