Linux字符设备驱动--Led设备驱动

①驱动源码

#include <linux/module.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/io.h>

#define LEDCON 0x56000010
#define LEDDAT 0x56000014

unsigned int *led_config;
unsigned int *led_data; 

struct cdev cdev;
dev_t devno;

int led_open(struct inode *node, struct file *filp)
{
    unsigned int led_config_value = ;

    led_config = ioremap(LEDCON, );
    led_data = ioremap(LEDDAT, );

    led_config_value = readl(led_config);
    led_config_value = led_config_value & (~(0xffff << ));
    led_config_value = led_config_value | (0x5555 << );

    printk("led_config_value = 0x%x\n", led_config_value);

    writel(led_config_value, led_config);
    led_config_value = readl(led_config);

    printk("led_config_value = 0x%x\n", led_config_value);

    return ;
}

long led_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
    unsigned int led_data_value = readl(led_data);

    switch (cmd)
    {
        case :
            led_data_value = led_data_value & (~(0x0f << ));

            printk("led_data_value = 0x%x\n", led_data_value);

            writel(led_data_value, led_data);
            led_data_value = readl(led_data);

            printk("led_data_value = 0x%x\n", led_data_value);

            return ;

        case :
            led_data_value = led_data_value | (0x0f << );

            printk("led_data_value = 0x%x\n", led_data_value);

            writel(0xff, led_data);
            led_data_value = readl(led_data);

            printk("led_data_value = 0x%x\n", led_data_value);

            return ;

        default:
            return -EINVAL;
    }
}

static struct file_operations led_fops =
{
    .open = led_open,
    .unlocked_ioctl = led_ioctl,
};

static int led_init(void)
{
    cdev_init(&cdev, &led_fops);

    alloc_chrdev_region(&devno,  ,  , "myled");
    cdev_add(&cdev, devno, );

    return ;
}

static void led_exit(void)
{
    cdev_del(&cdev);
    unregister_chrdev_region(devno,);
}

MODULE_LICENSE("GPL");

module_init(led_init);
module_exit(led_exit);

② Makefile

obj-m := Led.o
KDIR := /home/Linux/Kernal/linux-2.6.
all:
    make -C $(KDIR) M=$(PWD) modules CROSS_COMPILE=arm-linux- ARCH=arm
clean:
    rm -f *.ko *.o *.mod.o *.mod.c *.symvers *.bak *.order

③ 应用层测试代码

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>

int main(int argc, char *argv[])
{
     int fd;
     int cmd;

     if (argc < )
     {
         printf("please enter the second para!\n");
         return ;
     }

     cmd = atoi(argv[]); 

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

     if (cmd == )
         ioctl(fd, );
     else
         ioctl(fd, );    

     return ;
}

④ 测试步骤

（1）安装驱动模块：Led.ko

（2）查看主设备号：cat /proc/devices（查找led对应的主设备号）

（3）创建设备文件：mknod /dev/led c 主设备号 0

（4）运行测试代码进行测试