Linux驱动开发 通过字符设备驱动分步注册方式编写LED驱动

通过字符设备驱动分步注册方式编写LED驱动,完成设备文件和设备的绑定：

head.h：

#ifndef __HEAD_H__
#define __HEAD_H__ 
typedef struct{
    unsigned int MODER;
    unsigned int OTYPER;
    unsigned int OSPEEDR;
    unsigned int PUPDR;
    unsigned int IDR;
    unsigned int ODR;
}gpio_t;
#define PHY_LED1_ADDR 0X50006000
#define PHY_LED2_ADDR    0X50007000
#define PHY_LED3_ADDR 0X50006000
#define PHY_RCC_ADDR    0X50000A28
 
//构建LED开关的功能码，不添加ioctl第三个参数
#define  LED_ON _IO('l',1)
#define  LED_OFF _IO('l',0)
#endif 

Makefile:

modname?=mychrdev
arch?=arm
 
ifeq ($(arch),arm)
KERNELDIR:=/home/ubuntu/FSMP1A/linux-stm32mp-5.10.61-stm32mp-r2-r0/linux-5.10.61 #用于编译生成ARM架构的模块
else
KERNELDIR :=/lib/modules/$(shell uname -r )/build #用于生产x86架构的模块
endif
 
#定义变量保存模块化编译的文件路径
PWD:=$(shell pwd)
 
all:
 
#M=$(PWD)指定模块化编译的路径
	make -C $(KERNELDIR) M=$(PWD) modules
clean: #编译清除
	make -C $(KERNELDIR) M=$(PWD) clean
 
obj-m:=$(modname).o #指定将demo.o独立连接生产内核模块文件

LED.c:

#include 
#include 
#include
#include
#include
#include
#include
#include"head.h"
struct cdev *cdev;
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;
char kbuf[128]={0};
unsigned int major=0;
unsigned int minor=0;
dev_t devno;
module_param(major,uint,0664); //方便在命令行传递major值
struct class *cls;
struct device *dev;
 
int mycdev_open(struct inode *inode, struct file *file)
{
	int min=MINOR(inode->i_rdev); //根据打开的文件对应的设备号获取次设备号
	file->private_data=(void *)min;
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
 
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	int min=(int)file->private_data;
	switch(min)
	{
	case 0:  //控制LED1
		switch(cmd)
		{
		case LED_ON:
			//开灯
			vir_led1->ODR |= 1 << 10;
			break;
		case LED_OFF:
			//关灯
			vir_led1->ODR &= (~(1 << 10));
			break;
		}
		break;
	case 1:  //控制LED2
		switch(cmd)
		{
		case LED_ON:
			//开灯
			vir_led2->ODR |= 1 << 10;
			break;
		case LED_OFF:
			//关灯
			vir_led2->ODR &= (~(1 << 10));
			break;                                
		}
		break;
	case 2:  //控制LED3
		switch(cmd)
		{
		case LED_ON:
			//开灯
			vir_led3->ODR |= 1 << 8;
			break;
		case LED_OFF:
			//关灯
			vir_led3->ODR &= (~(1 << 8));
			break;                                
		}
		break;
	}
	return 0;	
}
 
int mycdev_close(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
 
//定义一个操作方法结构体对象并且初始化
struct file_operations fops = {
	.open=mycdev_open,
	.unlocked_ioctl = mycdev_ioctl,
	.release=mycdev_close,
};
 
int all_led_init(void)
{
	//寄存器地址的映射
	vir_led1 = ioremap(PHY_LED1_ADDR, sizeof(gpio_t));
	if(vir_led1 == NULL)
	{
		printk("ioremap filed: %d\n",__LINE__);
		return -ENOMEM;
	}
	vir_led2 = ioremap(PHY_LED2_ADDR, sizeof(gpio_t));
	if(vir_led2 == NULL)
	{
		printk("ioremap filed: %d\n",__LINE__);
		return -ENOMEM;
	}
	vir_led3 = vir_led1;
	vir_rcc = ioremap(PHY_RCC_ADDR,4);
	if(vir_rcc == NULL)
	{
		printk("ioremap filed: %d\n",__LINE__);
		return -ENOMEM;
	}
	printk("物理地址映射成功\n");
 
	//寄存器的初始化
	//RCC
	(*vir_rcc) |= (0x3 << 4);
	//LED1
	vir_led1->MODER &= (~(3 << 20));
    vir_led1->MODER |= (1 << 20);
    vir_led1->ODR &= (~(1 << 10));
	//LED2
	vir_led2->MODER &= (~(3 << 20));
    vir_led2->MODER |= (1 << 20);
    vir_led2->ODR &= (~(1 << 10));
	//LED3
    vir_led3->MODER &= (~(3 << 16));
    vir_led3->MODER |= (1 << 16);
    vir_led3->ODR &= (~(1 << 8));
	printk("寄存器初始化成功\n");
 
	return 0;
}
 
static int __init mycdev_init(void)
{
	int ret;
	cdev = cdev_alloc(); //申请一个字符设备驱动对象空间
	if(cdev==NULL)
	{
		printk("字符设备驱动对象申请空间失败\n");
		ret = -EFAULT;
		goto out1;
	}
	printk("申请对象空间成功\n");
 
	cdev_init(cdev, &fops); //字符设备驱动对象初始化
	if(major>0) //静态指定设备号
	{
		ret=register_chrdev_region(MKDEV(major,minor),3,"myled");
		if(ret)
		{
			printk("静态申请设备号失败\n");
			goto out2;
		}
	}
	else if(major==0) //动态申请设备号
	{
		ret=alloc_chrdev_region(&devno,minor,3,"myled");
		if(ret)
		{
			printk("动态申请设备号失败\n");
			goto out2;
		}
		major=MAJOR(devno); //获取主设备号
		minor=MINOR(devno); //获取次设备号
	}
	printk("申请设备号成功\n");
	//注册字符设备驱动对象 
	ret=cdev_add(cdev,MKDEV(major,minor),3);
    if(ret)
    {
        printk("注册字符设备驱动对象失败\n");
        goto out3;
    }
    printk("注册字符设备驱动对象成功\n");
    //向上提交目录信息
    cls=class_create(THIS_MODULE,"myled");
    if(IS_ERR(cls))
    {
        printk("向上提交目录失败\n");
        ret=-PTR_ERR(cls);
        goto out4;
    }
    printk("向上提交目录成功\n");
    //向上提交设备节点信息
    int i;
    for(i=0;i<3;i++)
    {
        dev=device_create(cls,NULL,MKDEV(major,i),NULL,"myled%d",i);
        if(IS_ERR(dev))
        {
            printk("向上提交设备节点信息失败\n");
            ret=-PTR_ERR(dev);
            goto out5;
        }
    }
    printk("向上提交设备信息成功\n");
    return 0;
out5:
    //释放前一次提交成功的设备信息
    for(--i;i>=0;i--)
    {
        device_destroy(cls,MKDEV(major,i));
    }
    class_destroy(cls);//释放目录
out4:
    cdev_del(cdev);
out3:
    unregister_chrdev_region(MKDEV(major,minor),3);
out2:
    kfree(cdev);
out1:
	return ret;
}
 
static void __exit mycdev_exit(void)
{
    //释放节点信息
    int i;
    for(i=0;i<3;i++)
    {
        device_destroy(cls,MKDEV(major,i));
    }
    //销毁目录
    class_destroy(cls);
	//取消地址映射
	iounmap(vir_led1);
	iounmap(vir_led2);
	iounmap(vir_rcc);
 
    //注销驱动对象
    cdev_del(cdev);
    //释放设备号
    unregister_chrdev_region(MKDEV(major,minor),3);
    //释放对象空间
    kfree(cdev);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");