一、思维导图
二、通过字符设备驱动的分步实现编写LED驱动，另外实现特备文件和设备的绑定
应用程序 test.c
#include
#include
#include
#include
#include
#include
#include
#include
#include "head.h"
int main(int argc, char const *argv[])
{
char buf[128]={0};
int a;
int fd=open("/dev/mycdev0",O_RDWR);
if(fd<0)
{
printf("打开设备文件失败\n");
exit(-1);
}
while(1)
{
//从终端读取
printf("请输入要实现的功能 ");
printf("0(关灯) 1(开灯)\n");
printf("请输入>");
scanf("%d",&a);
switch(a)
{
case 1:
ioctl(fd,LED_ON);
break;
case 0:
ioctl(fd,LED_OFF);
break;
}
}
close(fd);
return 0;
}
头文件 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
// 构建开灯关灯的功能码
#define LED_ON _IO('l', 1)
#define LED_OFF _IO('l', 0)
#endif
驱动程序 mycdev.c
#include
#include
#include
#include
#include
#include
#include
#include
#include "head.h"
struct cdev *cdev;
unsigned int major=0;
unsigned int minor=0;
dev_t devno;
char kbuf[128] = {0};
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;
struct class *cls;
struct device *dev;
int mycdev_open(struct inode *inode, struct file *file)
{
//获取打开的文件的次设备号
int min = MINOR(inode->i_rdev);
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)
{
//获取文件的次设备号
int min = (int)file->private_data;
switch (min)
{
case 0: // 开灯
switch (cmd)
{
case LED_ON: // LED1
vir_led1->ODR |= (0X1 << 10); //LED开
break;
case LED_OFF:
vir_led1->ODR &= (~(0X1 << 10));
break;
}
break;
case 1: // 关灯
switch (cmd)
{
case LED_ON: // LED1
vir_led2->ODR |= (0X1 << 10);
break;
case LED_OFF:
vir_led2->ODR &= (~(0X1 << 10));
break;
}
break;
case 2:
switch (cmd)
{
case LED_ON: // LED1
vir_led3->ODR |= (0X1 << 8);
break;
case LED_OFF:
vir_led3->ODR &= (~(0X1 << 8));
break;
}
break;
}
return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{
printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
return 0;
}
//定义操作方法结构体变量并赋值
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) |= (3 << 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_led1->MODER |= (1 << 16);
vir_led1->ODR &= (~(1 << 8));
printk("寄存器初始化成功\n");
return 0;
}
static int __init mycdev_init(void)
{
//1.申请一个对象空间cdev_alloc
int ret;
cdev = cdev_alloc();
if (NULL == cdev)
{
printk("申请字符设备驱动对象失败\n");
ret = -EFAULT;
goto out1;
}
printk("字符设备驱动对象申请成功\n");
//2.初始化对象cdev_ini
cdev_init(cdev,&fops);
//3.申请设备号register_chrdev_region()/alloc_chrdev_region()
if(0 == major)
{
ret = alloc_chrdev_region(&devno,minor,3,"mychrdev");
if(ret)
{
printk("动态申请设备号失败\n");
goto out2;
}
major=MAJOR(devno); //根据设备号获取主设备号
minor=MINOR(devno); //根据设备号获取次设备号
}
else //静态制定设备号
{
ret=register_chrdev_region(MKDEV(major,minor),3,"mychrdev");
if(ret)
{
printk("静态指定设备号失败\n");
goto out2;
}
}
printk("设备号申请成功\n");
//4.注册驱动对象 cdev_add
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");
//5.向上提交目录 class_create
cls = class_create(THIS_MODULE,"mychrdev");
if(IS_ERR(cls))
{
printk("向上提交目录失败\n");
goto out4;
}
printk("向上提交目录成功\n");
//6.向上提交设备节点信息 device_create
int i;
for(i=0;i<3;i++)
{
dev = device_create(cls,NULL,MKDEV(major,i),NULL,"mycdev%d",i);
if(IS_ERR(dev))
{
printk("向上提交设备节点失败\n");
goto out5;
}
}
printk("向上提交设备节点信息成功\n");
// 寄存器映射以及初始化
all_led_init();
return 0;
out5:
//奖提交成功的节点信息释放
for(--i;i>=0;i--)
{
device_destroy(cls,MKDEV(major,i));
}
//销毁目录
class_destroy(cls);
out4:
cdev_del(cdev);
out3:
unregister_chrdev_region(MKDEV(major,minor),3);
out2:
kfree(cdev);
out1:
return ret;
}
static void __exit mycdev_exit(void)
{
// 取消地址映射
iounmap(vir_led1);
iounmap(vir_led2);
iounmap(vir_rcc);
//1.销毁设备节点信息
int i;
for(i=0;i<3;i++)
{
device_destroy(cls,MKDEV(major,i));
}
//2.销毁目录
class_destroy(cls);
//3.注销字符设备驱动对象
cdev_del(cdev);
//4.释放设备号
unregister_chrdev_region(MKDEV(major,minor),3);
//5.释放申请到的字符设备驱动对象空间
kfree(cdev);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");
Makefile
modname ?= demo
arch ?= arm
ifeq ($(arch),arm) #通过命令行传过来的架构决定怎么编译
#KERBELDIR保存开发板内核源码路径
KERNELDIR := /home/ubuntu/FSMP1A/linux-stm32mp-5.10.61-stm32mp-r2-r0/linux-5.10.61
else
#保存UBUNTU内核源码路径
KERNELDIR := /lib/modules/$(shell uname -r)/build
endif
#PWD保存当前内核模块的路径
PWD := $(shell pwd)
all:
#make modules是模块化编译命令
#make -C $(KERNLEDIR) 执行make之前先切换到KERNELDIR对应的路径
#M=$(PWD)表示进行模块化编译的路径是PWD保存的路径
make -C $(KERNELDIR) M=$(PWD) modules
clean:
#编译清除
make -C $(KERNELDIR) M=$(PWD) clean
#将obj-m保存的文件单独链接为内核模块
obj-m := $(modname).o
效果实现
