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From a2948fd59692f1d30ce64035bed33b32997a0ad7 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Mon, 16 May 2022 12:16:46 +0100
Subject: [PATCH] overlays: Add gpio-hog overlay
Add an overlay to activate a hog on a specified pin. Note that
hogged GPIOs are not available for other uses, i.e. drivers or
gpioset/gpioget.
Inspired by a Forum thread here:
https://forums.raspberrypi.com/viewtopic.php?t=334286
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
arch/arm/boot/dts/overlays/Makefile | 1 +
arch/arm/boot/dts/overlays/README | 11 ++++++++
.../boot/dts/overlays/gpio-hog-overlay.dts | 27 +++++++++++++++++++
3 files changed, 39 insertions(+)
create mode 100644 arch/arm/boot/dts/overlays/gpio-hog-overlay.dts
--- a/arch/arm/boot/dts/overlays/Makefile
+++ b/arch/arm/boot/dts/overlays/Makefile
@@ -59,6 +59,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
goodix.dtbo \
googlevoicehat-soundcard.dtbo \
gpio-fan.dtbo \
+ gpio-hog.dtbo \
gpio-ir.dtbo \
gpio-ir-tx.dtbo \
gpio-key.dtbo \
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -1061,6 +1061,17 @@ Params: gpiopin GPIO use
millicelcius (default 55000)
+Name: gpio-hog
+Info: Activate a "hog" for a GPIO - request that the kernel configures it as
+ an output, driven low or high as indicated by the presence or absence
+ of the active_low parameter. Note that a hogged GPIO is not available
+ to other drivers or for gpioset/gpioget.
+Load: dtoverlay=gpio-hog,<param>=<val>
+Params: gpio GPIO pin to hog (default 26)
+ active_low If set, the hog drives the GPIO low (defaults
+ to off - the GPIO is driven high)
+
+
Name: gpio-ir
Info: Use GPIO pin as rc-core style infrared receiver input. The rc-core-
based gpio_ir_recv driver maps received keys directly to a
--- /dev/null
+++ b/arch/arm/boot/dts/overlays/gpio-hog-overlay.dts
@@ -0,0 +1,27 @@
+// Configure a "hog" on the specified GPIO
+/dts-v1/;
+/plugin/;
+
+#include <dt-bindings/gpio/gpio.h>
+
+/ {
+ compatible = "brcm,bcm2835";
+
+ fragment@0 {
+ target = <&gpio>;
+ __overlay__ {
+ hog: hog@1a {
+ gpio-hog;
+ gpios = <26 GPIO_ACTIVE_HIGH>;
+ output-high;
+ };
+ };
+ };
+
+ __overrides__ {
+ gpio = <&hog>,"reg:0",
+ <&hog>,"gpios:0";
+ active_low = <&hog>,"output-high!",
+ <&hog>,"output-low?";
+ };
+};
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