Linux设备驱动程序之三 ---- LED驱动程序的实现

LED驱动程序：

#include

#include

#include

#include

#include

#include  

#include  

int major;

dev_t dev_num;

static struct class *led_drv_class;

static struct device *led_drv_dev;

volatile unsigned long *gpbcon = NULL;

volatile unsigned long *gpbdat = NULL;

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

{

    //printk("first_drv_open\n");

    /* 配置GPB5,6,7,8为输出 */

    *gpbcon &= ~((0x3<<(5*2)) | (0x3<<(6*2)) | (0x3<<(7*2)) | (0x3<<(8*2)));

    *gpbcon |= ((0x1<<(5*2)) | (0x1<<(6*2)) | (0x1<<(7*2)) | (0x1<<(8*2)));

    return 0;

}

static ssize_t led_drv_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)

{

    int val;

    //printk("first_drv_write\n");

    copy_from_user(&val, buf, count); // copy_to_user();

    if (val == 1)

    {

        // 点灯

        *gpbdat &= ~((1<<5) | (1<<6) | (1<<7) | (1<<8));

    }

    else

    {

        // 灭灯

        *gpbdat |= ((1<<5) | (1<<6) | (1<<7) | (1<<8));

    }

    

    return 0;

}

static struct file_operations led_drv_fops = {

    .owner  =   THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */

    .open   =   led_drv_open,     

    .write = led_drv_write,   

};

static int led_drv_init(void)

{

    major = register_chrdev(0, "led_drv", &led_drv_fops); // 注册, 告诉内核

    dev_num = MKDEV(major,0);

    led_drv_class = class_create(THIS_MODULE, "led_drv");

    if (IS_ERR(led_drv_class))

    return PTR_ERR(led_drv_class);

    

    led_drv_dev = device_create(led_drv_class, NULL, dev_num, NULL, "led_drv");

    if (unlikely(IS_ERR(led_drv_dev)))

    return PTR_ERR(led_drv_dev);

    gpbcon = (volatile unsigned long *)ioremap(0x56000010, 16);

    gpbdat = gpbcon + 1;

    return 0;

}

static void led_drv_exit(void)

{

    unregister_chrdev(major, "led_drv"); // 卸载

    device_destroy(led_drv_class,dev_num);

    class_destroy(led_drv_class);

    iounmap(gpbcon);

}

module_init(led_drv_init);

module_exit(led_drv_exit);

MODULE_LICENSE("GPL");

LED测试程序：

#include

#include

#include

#include

int main(int argc, char **argv)

{

    int fd;

    int val = 1;

    fd = open("/dev/led_drv", O_RDWR);

    if (fd < 0)

    {

        printf("can't open!\n");

    }

    if (argc != 2)

    {

        printf("Usage :\n");

        printf("%s \n", argv[0]);

        return 0;

    }

    

    if (strcmp(argv[1], "on") == 0)

    {

        val  = 1;

    }

    else

    {

        val = 0;

    }

    write(fd, &val, 4);

    return 0;

}

注：我是TQ2440的开发板。

注：关于次设备号的使用，可以参考：

leds.rar

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