LED流水灯字符设备驱动

1.注册字符设备使用
int register_chrdev(unsigned int major, const char *name, struct file_operations *fops);
ret = register_chrdev(LED_MAJOR, DEVICE_NAME, &led_ops);
@major:主设备号
@name:设备名
@fops:操作函数
移除字符设备使用
int unregister_chrdev(unsigned int major, const char *name);
unregister_chrdev(LED_MAJOR, DEVICE_NAME);
2.gpio的使用
1)申请管脚
gpio_request(led_table[i],led_names[i]);
2)设置gpio输入输出高低电平
gpio_direction_output(led_table[i], 1);//低电平亮

-----------------------------------------------
flowing_lights_driver.c
/**
*s3c6410 linux2.6.35.7
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <mach/gpio.h>
#include <plat/gpio-cfg.h>
#include <linux/device.h>


#define LED_MAJOR 234
#define DEVICE_NAME "led_driver"

struct class *led_class;

static char *led_names[] = {"led0", "led1", "led2", "led3"};

static unsigned long led_table[] = {
	S3C64XX_GPM(0),
	S3C64XX_GPM(1),
	S3C64XX_GPM(2),
	S3C64XX_GPM(3),

};



int led_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	case 0:
		gpio_direction_output(led_table[0], 0);//低电平点亮
		gpio_direction_output(led_table[1], 1);
		gpio_direction_output(led_table[2], 1);
		gpio_direction_output(led_table[3], 1);
		break;
	case 1:
		gpio_direction_output(led_table[0], 1);//低电平点亮
		gpio_direction_output(led_table[1], 0);
		gpio_direction_output(led_table[2], 1);
		gpio_direction_output(led_table[3], 1);
		break;
	case 2:
		gpio_direction_output(led_table[0], 1);//低电平点亮
		gpio_direction_output(led_table[1], 1);
		gpio_direction_output(led_table[2], 0);
		gpio_direction_output(led_table[3], 1);
		break;
	case 3:
		gpio_direction_output(led_table[0], 1);//低电平点亮
		gpio_direction_output(led_table[1], 1);
		gpio_direction_output(led_table[2], 1);
		gpio_direction_output(led_table[3], 0);
		break;
	default:
		return -EINVAL;
		break;
	} 
	return 0;
}

struct file_operations led_ops = {
	.owner = THIS_MODULE,
	.ioctl = led_ioctl,
};

static int __init init_led(void)
{
	int i, ret;
	//creat own class under /sysfs ls /sys/class/led_class/led_driver/
	led_class = class_create(THIS_MODULE, "led_class");
	if(IS_ERR(led_class)) {
		printk("failed to creat class\n");
		return -1;
	}
	
	ret = register_chrdev(LED_MAJOR, DEVICE_NAME, &led_ops);
	if (ret < 0) {
		printk(DEVICE_NAME, "can't register major number\n");
	}
	//在dev/下创建设备节点，节点名为DEVICE_NAME ls -l /dev/led_driver 
	device_create(led_class, NULL, MKDEV(LED_MAJOR, 0), NULL, DEVICE_NAME, 0);
	
	for (i=0; i<4; i++) {
		//申请管脚
		gpio_request(led_table[i],led_names[i]);
		//在gpio引脚上写值之后，把这个端口设置为输出方式
		gpio_direction_output(led_table[i], 1);//低电平亮
	}
	printk("led init\n");
	return 0;
}

static void __exit exit_led(void)
{
	unregister_chrdev(LED_MAJOR, DEVICE_NAME);
}

module_init(init_led);
module_exit(exit_led);
MODULE_LICENSE("GPL");
----------------------------------------------------
led_test.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>

#define LED_DEV "/dev/led_driver" //# mknod /dev/led_driver c 234 0
int main(int argc, char **argv)
{
	int fd = 0;
	fd = open(LED_DEV, O_RDWR);
	
	
	if (fd < 0) {
		perror("open");
		exit(1);
	}
	
	while (1) {
		ioctl(fd, 0);
		printf("led0 is on\n");
		sleep(1);
		
		ioctl(fd, 1);
		printf("led1 is on\n");
		sleep(1);
		
		ioctl(fd, 2);
		printf("led2 is on\n");
		sleep(1);
		
		ioctl(fd, 3);
		printf("led3 is on\n");
		sleep(1);
	}
	close(fd);
	return 0;
}