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Ручное управление

Информацию о линиях GPIO можно Вручную можно управлять линиями GPIO с помощью команд gpioget. В случае выходной линии задать состояние с помощью gpioset. Получить информацию можно с помощью команды gpioinfo

Переименование линий gpio

Для переименования линий gpio требуется в DeviceTree включить следующий блок

&gpio {
	status = "okay";
	gpio-line-names =
	/*A0-A7*/	"nameA0","nameA1","nameA2","etc","","","","",
	/*B0-B7*/	"","","","","","","","",
	/*C0-C7*/	"","","","","","","","",
	/*D0-D7*/	"","","","","","","","",
	/*E0-E7*/	"","","","","","","","",
	/*F0-F7*/	"","","","","","","","",
	/*G0-G7*/	"","","","","","","","",
	/*H0-H7*/	"","","","","","","","",
	/*I0-I7*/	"","","","","","","","",
	/*J0-J7*/	"","","","","","","","",
	/*K0-K7*/	"","","","","","","","",
	/*L0-L7*/	"","","","","","","","",
	/*M0-M7*/	"","","","","","","","",
	/*N0-N7*/	"","","","","","","","",
	/*O0-O7*/	"","","","","","","","",
	/*P0-P7*/	"","","","","","","","",
	/*Q0-Q7*/	"","","","","","","","",
	/*R0-R7*/	"","","","","","","","",
	/*S0-S7*/	"","","","","","","","",
	/*T0-T7*/	"","","","","","","","",
	/*U0-U7*/	"","","","","","","","",
	/*V0-V7*/	"","","","","","","","",
	/*W0-W7*/	"","","","","","","","",
	/*X0-X7*/	"","","","","","","","",
	/*Y0-Y7*/	"","","","","","","","",
	/*Z0-Z7*/	"","","","","","","","",
	/*AA0-AA7*/	"","","","","","","","",
	/*AB0-AB7*/	"","","","","","","","",
	/*AC0-AC7*/	"","","","","","","","nameAC7";
};

Добавление GPIO кнопки

На данный момент я использую не создание кнопок в дереве ядра, а программу phosphor-gpio-monitor

Добавление кнопки в DeviceTree

  1. Добавить #include <dt-bindings/gpio/aspeed-gpio.h> в DevTree
  2. Добавить раздел gpio-keys в секцию / {..}; Пример:
gpio-keys {
		compatible = "gpio-keys";

		id-button {
			label = "id-button";
			gpios = <&gpio ASPEED_GPIO(N, 3) GPIO_ACTIVE_HIGH>;
			linux,code = <ASPEED_GPIO(N, 3)>;
		};

	};

После того как кнопка добавлена в дерево устройств, она начинает писать информацию по адресу /dev/input/by-path/platform-gpio-keys-event. Почему-то начались проблемы с platform-gpio-keys-event. И phosphor-gpio-monitor в режиме работы с отдельными сервисами. В итоге без добавления gpio-keys секции. Использую phosphor-gpio-monitor в multi режиме

Ручное управление GPIO

Основной способ

Для ручного управления GPIO используется libgpiod в том числе инструменты gpioinfo, gpioset, gpioget

SysFS

Так же есть поддержка устаревшего метода SysFS: cначала нужно найти номер пина. Для этого нужно к номеру базы добавить номер линии.

# ls /sys/class/gpio/  
export       gpiochip792  unexport

gpiochip792 - база 792

# gpiofind BMC_PWR_BMC
gpiochip0 208

линия 208 Значит номер пина 792+208=1000

# echo 1000 > /sys/class/gpio/export

После этого будет создан каталог /sys/class/gpio/gpio1000

Изменить направление gpio

echo in > /sys/class/gpio/gpio1000/direction
echo out > /sys/class/gpio/gpio1000/direction

Задать значение echo 1 > /sys/class/gpio/gpio1000/value Считать значение cat /sys/class/gpio/gpio1000/value