mini2440 LED驱动程序

    mini2440中提供的内核自带了LED的驱动程序，但该驱动是以杂项设备的形式编写，不太适合初学者，作者因为教学工作需要，花了一点时间，根据LDD3第三章内容将代码进行了修改，希望对一些初学者有所帮助。

    注意：本案例中采用了mdev设备文件管理系统以自动生成设备节点，有兴趣的同仁可以参考本博客关于mdev的相关介绍，对于初学者，不理解的可以手动创建设备节点进行本程序的测试。

    硬件连接如下，依次对应CPU上的GPB5～GPB8引脚：

    驱动程序：

#include
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#include 	//用于mdev操作


#define DEVICE_NAME "leds"


unsigned int gpio_major_number=0;
struct cdev gpio_dev;
struct class *gpio_class;
dev_t dev_nr;


static unsigned long led_table [] = {
S3C2410_GPB(5),
S3C2410_GPB(6),
S3C2410_GPB(7),
S3C2410_GPB(8),
};

static unsigned int led_cfg_table [] = {
S3C2410_GPIO_OUTPUT,
S3C2410_GPIO_OUTPUT,
S3C2410_GPIO_OUTPUT,
S3C2410_GPIO_OUTPUT,
};

static int sbc2440_leds_ioctl(
struct inode *inode,
struct file *file,
unsigned int cmd,
unsigned long arg)
{
switch(cmd) {
case 0:
case 1:
if (arg > 4) {
return -EINVAL;
}
s3c2410_gpio_setpin(led_table[arg], !cmd);
return 0;
default:
return -EINVAL;
}
}

static struct file_operations gpio_fops = {
.owner	=	THIS_MODULE,
.ioctl	=	sbc2440_leds_ioctl,
};

static int __init dev_init(void)
{
int ret,i;

for (i = 0; i < 4; i++) {		//引脚初始化
s3c2410_gpio_cfgpin(led_table[i], led_cfg_table[i]);
s3c2410_gpio_setpin(led_table[i], 0);
}

ret = alloc_chrdev_region(&dev_nr,0,1,DEVICE_NAME);	//动态分配设备号
gpio_major_number = MAJOR(dev_nr);
printk(KERN_INFO "Major Num ->%d\n",gpio_major_number);
if (ret<0)
{
printk(KERN_WARNING "gpio:can't get major number %d/n",gpio_major_number);
return ret;
}

cdev_init(&gpio_dev,&gpio_fops);		//初始化并向系统添加字符设备
gpio_dev.owner = THIS_MODULE;
//	gpio_dev.ops   = &gpio_fops;
ret = cdev_add(&gpio_dev,dev_nr,1);
if (ret)
{
unregister_chrdev_region(dev_nr,1);
printk(KERN_NOTICE "Error %d adding gpio device/n",ret);
return ret;
}

gpio_class = class_create(THIS_MODULE, "gpio_class");	//mdev相关，用于自动创建设备节点
if(IS_ERR(gpio_class))
{
printk("Err: failed in creating class./n");
return -1;
}
/* register your own device in sysfs, and this will cause mdev to create corresponding device node */
device_create(gpio_class,NULL,dev_nr, NULL, "gpio_dev%d" ,0);//设备节点名称gpio_dev0

return 0;
}

static void __exit dev_exit(void)
{
cdev_del(&gpio_dev);
device_destroy(gpio_class,dev_nr);
class_destroy(gpio_class);
unregister_chrdev_region(dev_nr,1);
}


module_init(dev_init);
module_exit(dev_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Allein.Cao");

测试程序：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>

int main(int argc, char **argv)
{
        int on;
        int led_no;
        int fd;
        if (argc != 3 || sscanf(argv[1], "%d", &led_no) != 1 || sscanf(argv[2],"%d", &on) != 1 ||
            on < 0 || on > 1 || led_no < 0 || led_no > 3) {
                fprintf(stderr, "Usage: leds led_no 0|1\n");
                exit(1);
        }

        fd = open("/dev/gpio_dev0", 0);	//打开设备节点，需与驱动程序对应起来
        if (fd < 0) {
                perror("open device leds");
                exit(1);
        }
        ioctl(fd, on, led_no);
        close(fd);
        return 0;
}