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");