GPIO LEDS

How to use leds-gpio driver to manage states of connected leds of your Armadeus board.

Introduction

You can manage a led connected to a GPIO pin. The managing is similar with the standard GPIO sysfs driver, but you have some new features like triggers (e.g. LED blinks based on disk access) .

Configuration

First, you need to enable the leds-gpio driver in your kernel.

Device Drivers  --->
     --- LED support
         [*] LED Class Support
         <*> LED Support for GPIO connected LEDs
              [*] Platform device bindings for GPIO LEDs

Then, in your apf27-dev.c, you need to define your LED before the variable platform_devices[].

/* GPIO LED */
#if 1
 
/* PORTF_14 used as leds-gpio (GPIO used as LED) */
static struct gpio_led apf27_gpio_leds[] = {
	{
		.name = "portf14",
		.default_trigger = "none",
		.gpio = (GPIO_PORTF | 14),
		//.active_low = 1,
		//.retain_state_suspended = 1,
		//.default_state = LEDS_GPIO_DEFSTATE_ON,
	},
};

static struct gpio_led_platform_data apf27_gpio_leds_platform_data = {
	.leds = apf27_gpio_leds,
	.num_leds = ARRAY_SIZE(apf27_gpio_leds),
};

static struct platform_device apf27_gpio_leds_device = {
	.name = "leds-gpio",
	.id = 0,
	.dev = {
		.platform_data = &apf27_gpio_leds_platform_data,
	},
};
# define LEDS_GPIO &apf27_gpio_leds_device,
#else
# define LEDS_GPIO
#endif

Add the button to get it recognized by the card.

static struct platform_device *platform_devices[] __initdata = {
	ALSA_SOUND
	LEDS_GPIO
};

# ls /sys/class/leds/portf14/
brightness      max_brightness  subsystem       uevent
device          power           trigger