Android系统--灯光系统驱动编写

Android系统开发--Android灯光系统tiny4412_led_class驱动编写

框架分析

• led_classdev_4412结构体

  • 创建led_classdev_4412结构体

  • 分配结构体空间

struct led_classdev_4412 {

    struct led_classdev cdev;

    int gpio;

};

struct led_classdev {

	const char		*name;

	int			 brightness;

	int			 max_brightness;

	int			 flags;

	/* Lower 16 bits reflect status */

#define LED_SUSPENDED		(1 << 0)

	/* Upper 16 bits reflect control information */

#define LED_CORE_SUSPENDRESUME	(1 << 16)

	/* Set LED brightness level */

	/* Must not sleep, use a workqueue if needed */

	void		(*brightness_set)(struct led_classdev *led_cdev,

					  enum led_brightness brightness);

	/* Get LED brightness level */

	enum led_brightness (*brightness_get)(struct led_classdev *led_cdev);

	/*

	 * Activate hardware accelerated blink, delays are in milliseconds

	 * and if both are zero then a sensible default should be chosen.

	 * The call should adjust the timings in that case and if it can't

	 * match the values specified exactly.

	 * Deactivate blinking again when the brightness is set to a fixed

	 * value via the brightness_set() callback.

	 */

	int		(*blink_set)(struct led_classdev *led_cdev,

				     unsigned long *delay_on,

				     unsigned long *delay_off);

	struct device		*dev;

	struct list_head	 node;			/* LED Device list */

	const char		*default_trigger;	/* Trigger to use */

	unsigned long		 blink_delay_on, blink_delay_off;

	struct timer_list	 blink_timer;

	int			 blink_brightness;

#ifdef CONFIG_LEDS_TRIGGERS

	/* Protects the trigger data below */

	struct rw_semaphore	 trigger_lock;

	struct led_trigger	*trigger;

	struct list_head	 trig_list;

	void			*trigger_data;

#endif

};

 led_devs = kzalloc(sizeof(struct led_classdev_4412) * sizeof(led_gpios)/sizeof(led_gpios[0]), GFP_KERNEL);

• 设置led_classdev_4412中属性，并注册结构体--led_classdev_register

• led_classdev_4412属性如下：

  1. led_cdev->max_brightness

  2. led_cdev->brightness_set

  3. led_cdev->flags

  4. led_cdev->brightness

  5. led_cdev->name

实现代码如下：

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"},

};

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);               //设置为LED_OFF

     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;          //设置为对应的引脚设备名

     led_devs[i].gpio = led_gpios[i].gpio;               //记录对应引脚                

     /* 3. led_classdev_register */

     ret = led_classdev_register(NULL, &led_devs[i].cdev);

     /*注册失败之后，将之前注册的设备注销，并且释放空间*/

     if (ret) {

         i--;

     while (i >= 0) {

             led_classdev_unregister(&led_devs[i].cdev);

             i--;

         }

     kfree(led_devs);

     return -EIO;

     }

 }

 return 0;

}