练习: 通过字符设备驱动分步注册方式编写LED灯的驱动,应用程序使用ioctl函数编写硬件控制逻辑
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#define LED_ON _IOW('l',1,int)//开灯
#define LED_OFF _IOW('l',0,int)//关灯#endif
驱动代码
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/slab.h>
#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)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);return 0;
}
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{int which;int ret=copy_from_user(&which,(unsigned int *)arg,4);if(ret){printk("copy_from_user err\n");return ret;}// 根据用户空间功能码的不同实现硬件不同的控制switch (cmd){case LED_ON: // 开灯switch (which){case 1: // LED1vir_led1->ODR |= (0X1 << 10);break;case 2: // LED2vir_led2->ODR |= (0X1 << 10);break;case 3: // LED3vir_led3->ODR |= (0X1 << 8);break;}break;case LED_OFF: // 关灯switch (which){case 1:vir_led1->ODR &= (~(0X1 << 10));break;case 2:vir_led2->ODR &= (~(0X1 << 10));break;case 3: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);// 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)
{// 字符设备驱动注册// major = register_chrdev(0, "mychrdev", &fops);// if (major < 0)// {// printk("字符设备驱动注册失败\n");// return major;// }/*** 分步实现字符设备驱动注册*/int ret;//1. 分配字符设备驱动对象cdev = cdev_alloc();if (cdev == NULL) {printfk("申请字符设备驱动对象失败\n");ret = -EFAULT;goto OUT1;}//2. 初始化字符设备驱动对象cdev_init(cdev, &fops);//3. 申请设备号if (major > 0) {//静态指定ret = register_chrdev_region(MKDEV(major, minor), 3, "mycdev");if (ret) {printk("静态指定设备号失败\n");goto OUT2;}} else {ret = alloc_chrdev_region(&devno, minor, 3, "mycdev");if (ret) {printk("动态指定设备号失败\n");goto OUT2;}minor = MINOR(devno);major = MAJOR(devno);}//4. 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, "mycdev");if (IS_ERR(cls)){printk("向上提交目录信息失败\n");return -PTR_ERR(cls);}printk("向上提交目录信息成功\n");// 向上提交设备信息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");return -PTR_ERR(cls);}}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:for(--i;i>=0;i--) {device_destroy(cls,MKDEV(major,i));//释放提交成功的设备信息}class_destroy(cls);//销毁目录
OUT4:cdev_del(cdev);
OUT3:unregister_chrdev_region(MKDEV(major,minor),3);
OUT2:kfree(cdev);
OUT1:return ret;
}
static void __exit mycdev_exit(void)
{// 取消地址映射iounmap(vir_led1);iounmap(vir_led2);iounmap(vir_rcc);// 销毁设备信息int i;for (i = 0; i < 3; i++){device_destroy(cls, MKDEV(major, i));}// 销毁目录信息class_destroy(cls);// 注销字符设备驱动unregister_chrdev(major, "mychrdev");
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");
应用层测试代码
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include "head.h"int main(int argc, char const *argv[])
{char buf[128] = {0};int a, b;int fd = open("/dev/mycdev0", O_RDWR);if (fd < 0){printf("打开设备文件失败\n");exit(-1);}while (1){printf("请输入要实现的功能:1(开灯)0(关灯>)");scanf("%d", &a);printf("请输入要控制的灯:1(LED1) 2(LED2) 3(LED3)>");scanf("%d", &b);switch (a){case 1:ioctl(fd, LED_ON, &b);break;case 0:ioctl(fd, LED_OFF, &b);break;}}close(fd);return 0;
}