灯光系统

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/delay.h>
 
#include <linux/gpio.h>
#include <mach/gpio.h>
#include <plat/gpio-cfg.h>
#include <linux/backlight.h>
#include <linux/leds.h>


static struct led_desc {
             char *name;
             int gpio;
};

static struct led_desc tiny4412_led[] = {
            {"led0", EXYNOS4212_GPM4(0)},
            {"led1", EXYNOS4212_GPM4(1)},
            {"led2", EXYNOS4212_GPM4(2)},
            {"led3", EXYNOS4212_GPM4(3)},
};

struct led_classdev_cdev {
            struct led_classdev led_dev;
            int gpio;
};

struct led_classdev_cdev *led_dev[4];

static int PIN_NUM = sizeof(tiny4412_led)/sizeof(tiny4412_led[0]);

void tiny4412_brightness_set(struct led_classdev *led_cdev,
                      enum led_brightness brightness)
{
    struct led_classdev_cdev *cdev = (struct led_classdev_cdev *)led_cdev;
    if (brightness == LED_OFF)
         gpio_set_value(cdev->gpio, 1);
    else
         gpio_set_value(cdev->gpio, 0);
    led_cdev->brightness = brightness;
}

int led_tiny4412_init(void)
{
   int i;
   
   for (i = 0; i < PIN_NUM; i++) {
        s3c_gpio_cfgpin(tiny4412_led[i].gpio, S3C_GPIO_OUTPUT);
        gpio_set_value(tiny4412_led[i].gpio, 1);
        led_dev[i] = kzalloc(sizeof(struct led_classdev_cdev), GFP_KERNEL);
        led_dev[i]->led_dev.brightness_set = tiny4412_brightness_set;
        led_dev[i]->led_dev.max_brightness = LED_FULL;    
        led_dev[i]->led_dev.brightness = LED_OFF;
        led_dev[i]->led_dev.flags = LED_CORE_SUSPENDRESUME;
        led_dev[i]->led_dev.name = tiny4412_led[i].name;
        led_dev[i]->gpio = tiny4412_led[i].gpio;

        led_classdev_register(NULL, &(led_dev[i]->led_dev));
   }
   return 0;
}

void led_tiny4412_exit(void)
{
   int i;
    for (i = 0; i < PIN_NUM; i++) {
       led_classdev_unregister(&(led_dev[i]->led_dev));
       kfree(led_dev[i]);
    }
}

module_init(led_tiny4412_init);
module_exit(led_tiny4412_exit);

MODULE_LICENSE("GPL");

将程序加入drivers/leds目录下：

make menuconfig 配置内核：将LED CLASS / LED trigger 加入编译进内核

make zImage

烧写内核

ls /sys/class/led*

led0
led1
led2
led3

echo 255 > /sys/class/leds/led0/brightness 点亮第一个LED灯

HAL程序：参考com_android_server_lights_LightsService.cpp