【驱动开发】LED灯的亮灭——通过字符设备驱动的分步实现编写LED驱动，实现设备文件和设备的绑定

头文件：

#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;//LED灯的寄存器地址
#define LED1_ADDR 0X50006000
#define LED2_ADDR 0X50007000
#define LED3_ADDR 0X50006000
#define RCC_ADDR 0X50000A28//构建LED开关的功能码，ioctl第三个参数
#define LED_ON _IO('l',1)
#define LED_OFF _IO('l',0)#endif

驱动程序：

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include "head.h"
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/slab.h>struct cdev *cdev = NULL;
unsigned major = 0;
unsigned minor = 0;
module_param(major, uint, 0664);
dev_t devno;
char kbuf[128] = {0};
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
// 定义指针指向映射后的虚拟内存
unsigned int *vir_rcc;
struct class *cls;
struct device *dev;// 封装操作方法
int mycdev_open(struct inode *inode, struct file *file)
{// 设备文件和设备绑定// 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){int min = (int)file->private_data;switch (min){case 0: // 控制LED1switch (cmd){case LED_ON: // 开灯vir_led1->ODR |= (0x1 << 10);break;case LED_OFF: // 关灯vir_led1->ODR &= (~(0x1 << 10));break;}break;case 1: // 控制LED2switch (cmd){case LED_ON: // 开灯vir_led2->ODR |= (0x1 << 10);break;case LED_OFF: // 关灯vir_led2->ODR &= (~(0x1 << 10));break;}break;case 2: // 控制LED3switch (cmd){case LED_ON: // 开灯vir_led3->ODR |= (0x1 << 8);break;case LED_OFF: // 关灯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(LED1_ADDR, sizeof(gpio_t));if (vir_led1 == NULL){printk("ioremap filed：%d\n", __LINE__);return -ENOMEM;}vir_led2 = ioremap(LED2_ADDR, sizeof(gpio_t));if (vir_led2 == NULL){printk("ioremap filed：%d\n", __LINE__);return -ENOMEM;}vir_led3 = vir_led1;vir_rcc = ioremap(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);// led1vir_led1->MODER &= (~(3 << 20));vir_led1->MODER |= (1 << 20);vir_led1->ODR &= (~(1 << 10));// led2vir_led2->MODER &= (~(3 << 20));vir_led2->MODER |= (1 << 20);vir_led2->ODR &= (~(1 << 10));// led3vir_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_allocint ret;cdev = cdev_alloc();if (cdev == NULL){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_initcdev_init(cdev, &fops);// 3.申请设备号  register_chrdev_region()/alloc_chrdev_region()if (major == 0) // 动态申请{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{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_addret = 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");// 相关寄存器地址映射及初始化all_led_init();// 5.向上提交目录  class_createcls = 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_createint 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");return 0;
out5:// 将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)
{// 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);// 取消物理内存的映射iounmap(vir_led1);iounmap(vir_led2);iounmap(vir_rcc);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用程序： 

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include "head.h"
#include <sys/ioctl.h>
int main(int argc, char const *argv[])
{int a;char buf[128] = {0};int fd = open("/dev/mycdev0", O_RDWR);if (fd < 0){printf("打开设备文件失败\n");return -1;}printf("打开设备文件成功\n");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);getchar();switch (a){case 1:ioctl(fd, LED_ON); // 第三个参数为指针break;case 0:ioctl(fd, LED_OFF);break;}}close(fd);return 0;
}