ARM-linux嵌入式内核驱动——LCD背光的驱动

/************************************************

LCD背光的驱动，在TX2440A开发板上做测试

维护记录：  2009-10-30  V1.0   

linux内核：2.6.31.4

硬件接法：

        GPG4 --  LCD_PWREN

驱动用法：

        设备名称：TX2440-backlight

*************************************************/

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

 

#define DEVICE_NAME  "TX2440-backlight"

static int BACKLIGHT_Major = 0;         /* 主设备号 */

 

static unsigned int bl_state;

 

static inline void set_bl(int state)

{

    bl_state = !!state;

    s3c2410_gpio_setpin(S3C2410_GPG(4), bl_state);

}

 

static inline unsigned int get_bl(void)

{

    return bl_state;

}

 

static int TX2440_backlight_open(struct inode *inode, struct file *file)

{

    printk("TX2440-BACKLIGHT Driver Open Called!\n");

    return 0;

}

 

static int TX2440_backlight_release(struct inode *inode, struct file *file)

{

    printk("TX2440-BACKLIGHT Driver Release Called!\n");

    return 0;

}

 

static ssize_t TX2440_backlight_write(struct file *file, const char *buffer, size_t count, loff_t * ppos)

{

    unsigned char ch;

    int ret;

   

    if (count == 0)

    {

        return count;

    }

   

    ret = copy_from_user(&ch, buffer, sizeof ch) ? -EFAULT : 0;

   

    if (ret)

    {

        return ret;

    }

 

    ch &= 0x01;

    set_bl(ch);

       

    return count;

}

 

static ssize_t TX2440_backlight_read(struct file *filp, char *buffer, size_t count, loff_t *ppos)

{

    int ret;

    unsigned char str[] = {'0', '1' };

 

    if (count == 0)

    {

        return 0;

    }

 

    ret = copy_to_user(buffer, str + get_bl(), sizeof(unsigned char) ) ? -EFAULT : 0;

 

    if (ret)

    {

        return ret;

    }

 

    return sizeof(unsigned char);

}

 

static struct file_operations TX2440_backlight_fops =

{

    .owner   =  THIS_MODULE,

    .open    =  TX2440_backlight_open,

    .release =  TX2440_backlight_release,

    .read    =  TX2440_backlight_read,

    .write   =  TX2440_backlight_write,

};

 

static struct class *backlight_class;

 

static int __init TX2440_backlight_init(void)

{

    printk("TX2440 BACKLIGHT DRIVER MODULE INIT\n");

 

    s3c2410_gpio_cfgpin(S3C2410_GPG(4), S3C2410_GPIO_OUTPUT);

    set_bl(1);

   

    BACKLIGHT_Major = register_chrdev(0, DEVICE_NAME, &TX2440_backlight_fops);

    if (BACKLIGHT_Major < 0)

    {

        printk(DEVICE_NAME " can't register major number\n");

        return BACKLIGHT_Major;

    }

    printk("register TX2440-BACKLIGHT Driver OK! Major = %d\n", BACKLIGHT_Major);

 

    backlight_class = class_create(THIS_MODULE, DEVICE_NAME);

    if(IS_ERR(backlight_class))

    {

        printk("Err: failed in TX2440-BACKLIGHT class. \n");

        return -1;

    }

 

    device_create(backlight_class, NULL, MKDEV(BACKLIGHT_Major, 0), NULL, DEVICE_NAME);

 

    printk(DEVICE_NAME " initialized\n");

   

    return 0;

}

 

 

static void __exit TX2440_backlight_exit(void)

{

    printk("TX2440 BACKLIGHT DRIVER MODULE EXIT\n");

    unregister_chrdev(BACKLIGHT_Major, DEVICE_NAME);

    device_destroy(backlight_class, MKDEV(BACKLIGHT_Major, 0));

    class_destroy(backlight_class);

}

 

module_init(TX2440_backlight_init);

module_exit(TX2440_backlight_exit);

 

MODULE_AUTHOR("www.txmcu.com");    

MODULE_DESCRIPTION("TX2440 BACKLIGHT Driver");  

MODULE_LICENSE("GPL");

 

源代码： TX2440_backlight.rar