Android system ：led_class驱动

一、代码：

leds_4412.c

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/miscdevice.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/leds.h>

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

static struct led_desc led_gpios[] = {
    {EXYNOS4212_GPM4(0), "led1"},
    {EXYNOS4212_GPM4(1), "led2"},
    {EXYNOS4212_GPM4(2), "led3"},
    {EXYNOS4212_GPM4(3), "led4"},
};

struct led_classdev_4412 {
    struct led_classdev cdev;
    int gpio;
};


static struct led_classdev_4412 *led_devs;
static void     brightness_set_4412(struct led_classdev *led_cdev,
              enum led_brightness brightness)
{
    struct led_classdev_4412 *dev = (struct led_classdev_4412 *)led_cdev;

    led_cdev->brightness = brightness;

    if (brightness != LED_OFF)
        gpio_set_value(dev->gpio, 0);
    else
        gpio_set_value(dev->gpio, 1);
}


static int leds_init(void)
{
    int i;
    int ret;
    
    /* 1. alloc led_classdev */
    led_devs = kzalloc(sizeof(struct led_classdev_4412) * sizeof(led_gpios)/sizeof(led_gpios[0]), GFP_KERNEL);
    if (led_devs == NULL) {
        printk("No memory for device
");
        return -ENOMEM;
    }
    
    for (i = 0; i < sizeof(led_gpios)/sizeof(led_gpios[0]); i++)
    {

        s3c_gpio_cfgpin(led_gpios[i].gpio, S3C_GPIO_OUTPUT);
        gpio_set_value(led_gpios[i].gpio, 1);

        /* 2. set */
        led_devs[i].cdev.max_brightness = LED_FULL;
        led_devs[i].cdev.brightness_set = brightness_set_4412;
        led_devs[i].cdev.flags = LED_CORE_SUSPENDRESUME;
        led_devs[i].cdev.brightness = LED_OFF;
        led_devs[i].cdev.name = led_gpios[i].name;
        //led_devs[i].cdev.default_trigger = "timer";
        led_devs[i].gpio = led_gpios[i].gpio;

        /* 3. led_classdev_register */
        ret = led_classdev_register(NULL, &led_devs[i].cdev);
        if (ret) {
            i--;
            while (i >= 0) {
                led_classdev_unregister(&led_devs[i].cdev);
                i--;
            }
            kfree(led_devs);
            return -EIO;
        }
    }
    
    return 0;
}

static void leds_exit(void)
{
    int i;
    for (i = 0; i < sizeof(led_gpios)/sizeof(led_gpios[0]); i++)
    {
        led_classdev_unregister(&led_devs[i].cdev);
    }
    kfree(led_devs);
}

module_init(leds_init);
module_exit(leds_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("sheldon");

二、编译测试：

把 leds_4412.c 放到drivers/leds
修改 drivers/leds/Makefile:
obj-y += leds_4412.o

重新配置内核
make menuconfig

CONFIG_LEDS_CLASS
CONFIG_LEDS_TRIGGERS
CONFIG_LEDS_TRIGGER_TIMER

-> Device Drivers
-> LED Support
[*] LED Class Support
[*] LED Trigger support
<*> LED Timer Trigger

重新编译内核： make zImage