Android系统开发--Android灯光系统tiny4412_led_class驱动编写
框架分析
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led_classdev_4412结构体
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创建led_classdev_4412结构体
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分配结构体空间
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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);
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设置led_classdev_4412中属性，并注册结构体--led_classdev_register
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led_classdev_4412属性如下：
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led_cdev->max_brightness
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led_cdev->brightness_set
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led_cdev->flags
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led_cdev->brightness
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led_cdev->name
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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;
}