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 = 0;
    
    led_config = ioremap(LEDCON, 4);
    led_data = ioremap(LEDDAT, 4);
    
    led_config_value = readl(led_config);
    led_config_value = led_config_value & (~(0xffff << 10));
    led_config_value = led_config_value | (0x5555 << 10);
    
    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 0;
}

long led_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
    unsigned int led_data_value = readl(led_data);
    
    switch (cmd)
    {
        case 1:
            led_data_value = led_data_value & (~(0x0f << 5));
            
            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 0;
        
        case 0:
            led_data_value = led_data_value | (0x0f << 5);
            
            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 0;
        
        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, 0 , 1 , "myled");
    cdev_add(&cdev, devno, 1);
    
    return 0;    
}

static void led_exit(void)
{
    cdev_del(&cdev);
    unregister_chrdev_region(devno,1);
}

MODULE_LICENSE("GPL");

module_init(led_init);
module_exit(led_exit);

② Makefile

obj-m := Led.o
KDIR := /home/Linux/Kernal/linux-2.6.29
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 < 2)
     {
         printf("please enter the second para!\n");
         return 0;    
     }
     
     cmd = atoi(argv[1]); 
     
     fd = open("/dev/led", O_RDWR);
     
     if (cmd == 1)
         ioctl(fd, 1);
     else
         ioctl(fd, 0);    
         
         
     return 0;
}

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