openwrt/package/base-files/files/etc/init.d/gpio_switch
Kuan-Yi Li c5bf9a8ced base-files: gpio switch: add named GPIO support
Previously, gpio_switch only accepts GPIO pin number as input. Once a
GPIO pin is exported and named by device tree, its pin state cannot be
configured and saved across reboots by UCI.

This patch adds support for named GPIO pins. Thus GPIO pin can be
exported by device tree with active high/low correctly configured,
having human-readable name in /sys/class/gpio/ is also now possible.

More importantly, GPIO pins which are referenced by name will be immune
from pin mapping breakage while unintentional pin number changes are
introduced by kernel or driver updates.

Signed-off-by: Kuan-Yi Li <kyli@abysm.org>
2020-06-18 20:08:18 +02:00

67 lines
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Executable File

#!/bin/sh /etc/rc.common
# Copyright (C) 2015 OpenWrt.org
START=94
STOP=10
USE_PROCD=1
load_gpio_switch()
{
local name
local gpio_pin
local value
config_get gpio_pin "$1" gpio_pin
config_get name "$1" name
config_get value "$1" value 0
[ -z "$gpio_pin" ] && {
echo >&2 "Skipping gpio_switch '$name' due to missing gpio_pin"
return 1
}
local gpio_path
if [ -n "$(echo "$gpio_pin" | grep -E "^[0-9]+$")" ]; then
gpio_path="/sys/class/gpio/gpio${gpio_pin}"
# export GPIO pin for access
[ -d "$gpio_path" ] || {
echo "$gpio_pin" >/sys/class/gpio/export
# we need to wait a bit until the GPIO appears
[ -d "$gpio_path" ] || sleep 1
}
# direction attribute only exists if the kernel supports changing the
# direction of a GPIO
if [ -e "${gpio_path}/direction" ]; then
# set the pin to output with high or low pin value
{ [ "$value" = "0" ] && echo "low" || echo "high"; } \
>"$gpio_path/direction"
else
{ [ "$value" = "0" ] && echo "0" || echo "1"; } \
>"$gpio_path/value"
fi
else
gpio_path="/sys/class/gpio/${gpio_pin}"
[ -d "$gpio_path" ] && {
{ [ "$value" = "0" ] && echo "0" || echo "1"; } \
>"$gpio_path/value"
}
fi
}
service_triggers()
{
procd_add_reload_trigger "system"
}
start_service()
{
[ -e /sys/class/gpio/ ] && {
config_load system
config_foreach load_gpio_switch gpio_switch
}
}