Linux驱动开发——MISC驱动

MISC 驱动是最简单的字符设备驱动，学习 MISC 驱动将会为学习字符设备驱动奠定基础。

杂项设备是字符设备的一种，杂项设备可以自动生成设备节点。

misc设备主设备号都是10

​ 设备号：

​ 主设备号 用来标识一个类型的驱动

​ 次设备号 用来标识同一类型中不同的设备号

以泰山派RK3566点灯为例

驱动代码：

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/io.h>
#define MY_NAME "hx_led"
#define PMU_GRF_GPIO3B_IOMUX_H 0xFDC6004C
#define GPIO_SWPORT_DDR_L 0xFE760008
#define GPIO_SWPORT_DR_L 0xFE760000

char kbuf[128] = {0};
unsigned int *virt_iomux;
unsigned int *virt_ddr;
unsigned int *virt_dr;

int my_open (struct inode *inode, struct file *file)
{
    printk("open!\n");
    return 0;
}
ssize_t my_read (struct file *file, char __user *ubuf, size_t size, loff_t *offset)
{
    if(size > sizeof(kbuf)) size = sizeof(kbuf);
    if(copy_to_user(ubuf,kbuf,size))
    {
        printk("copy data to user fail!\n");
        return -EIO;
    }
    return size;
}
ssize_t my_write (struct file *file, const char __user *ubuf, size_t size, loff_t *offset)
{
    if(size > sizeof(kbuf)) size = sizeof(kbuf);
    if(copy_from_user(kbuf,ubuf,size))
    {
        printk("copy data form user fail!\n");
        return -EIO;
    }
    if(kbuf[0] == '1')
    {
        *virt_dr |= 0x10001000;
    }
    return size;
}
int my_close (struct inode *inode, struct file *file)
{
    printk("close!\n");
    return 0;
}

static const struct file_operations fops = {
    .owner	 = THIS_MODULE,
    .open = my_open,
    .read = my_read,
    .write = my_write,
    .release = my_close
};

static struct miscdevice led_miscdev = {
    .minor = MISC_DYNAMIC_MINOR,
    .name = MY_NAME,
    .fops = &fops,
};

int my_led_init(void)
{
    virt_iomux = ioremap(PMU_GRF_GPIO3B_IOMUX_H, 4);
    if(virt_iomux == NULL)
    {
        printk("ioremap iomux register error! \n");
        return -ENOMEM;
    }

    virt_ddr = ioremap(GPIO_SWPORT_DDR_L, 4);
    if(virt_ddr == NULL)
    {
        printk("ioremap ddr register error! \n");
        return -ENOMEM;
    }	
    virt_dr = ioremap(GPIO_SWPORT_DR_L, 4);
    if(virt_dr == NULL)
    {
        printk("ioremap dr register error! \n");
        return -ENOMEM;
    }
    *virt_iomux |= 0x70000;
    *virt_ddr |= 0x10001000;
    *virt_dr |= 0x10000000;
    return 0;
}

int my_led_deinit(void)
{
    *virt_dr |= 0x10000000;
    iounmap(virt_iomux);
    iounmap(virt_ddr);
    iounmap(virt_dr);
    return 0;
}

static int __init mycdev_init(void)
{
    int ret;
    ret = misc_register(&led_miscdev);
    if (ret) {
        printk("misc_register failed!\n");
        return ret;
    }
    printk("misc device registered\n");
    my_led_init();
    return 0;
}

static void __exit mycdev_exit(void)
{
    my_led_deinit();
    printk("hello world %s\n","exit");
    misc_deregister(&led_miscdev);
}

module_init(mycdev_init);
module_exit(mycdev_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("LiSir LiSir@qq.com");

应用代码

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>


int main()
{
	int fd = open("/dev/hx_led",O_RDWR);
	if(fd == -1)
	{
		printf("open failed");
		return -1;
	}
	while(1)
	{
		write(fd,"1",1);
		usleep(200000);
		write(fd,"0",1);
		usleep(200000);
	}
	close(fd);
	return 0;
}

Makefile

KERN_DIR = /home/hxbj/tspi/linux/kernel

all:
	make -C $(KERN_DIR) M=`pwd` modules 
	$(CROSS_COMPILE)gcc -o app app.c 

clean:
	make -C $(KERN_DIR) M=`pwd` modules clean
	rm -rf modules.order
	rm -f app

obj-m	+= led_drv.o