0722_驱动3 地址映射驱动点灯
一、为什么需要地址映射
在芯片手册上查看到的地址属于物理地址,在硬件层
在内核空间地址属于虚拟地址,在内核层
在驱动中,操作的是虚拟地址
需要将物理地址《--mmu内存管理单元--》虚拟地址映射
二、映射API接口
void *ioremap(unsigned long port, unsigned long size)#include <linux/io.h>
函数功能:将物理地址映射为虚拟地址
参数:
port:物理地址
size:映射大小
返回值: 成功返回映射虚拟地址首地址 失败返回NULL
三、取消映射API接口
void iounmap(volatile void *addr)
函数功能:取消地址映射
参数:
addr:取消映射虚拟地址首地址
返回值:无
四、编写驱动程序
myled.h:
#ifndef __MYLED_H__ #define __MYLED_H__enum led{LED1, //0LED2, //1LED3, //2 };typedef struct {volatile unsigned int MODER; // 0x00volatile unsigned int OTYPER; // 0x04volatile unsigned int OSPEEDR; // 0x08volatile unsigned int PUPDR; // 0x0Cvolatile unsigned int IDR; // 0x10volatile unsigned int ODR; // 0x14volatile unsigned int BSRR; // 0x18volatile unsigned int LCKR; // 0x1C volatile unsigned int AFRL; // 0x20 volatile unsigned int AFRH; // 0x24volatile unsigned int BRR; // 0x28volatile unsigned int res;volatile unsigned int SECCFGR; // 0x30 }gpio_t;#define GPIOE (0x50006000) //GPIOE组基地址 #define GPIOF (0x50007000) //GPIOF组基地址 #define RCC_MP_AHB4ENSETR 0x50000A28//RCC_MP_AHB4ENSETR寄存器地址#endif
demo.c:
#include <linux/init.h> #include <linux/module.h> #include <linux/fs.h> #include <linux/uaccess.h> #include <linux/io.h> #include "myled.h"#define CNAME "myled" unsigned int major = 0; char kbuf[128] = {}; unsigned int* rcc_virt = NULL; //RCC虚拟地址 gpio_t* gpioe_virt = NULL; //gpioe组虚拟地址 gpio_t*gpiof_virt = NULL; //gpiof组虚拟地址#define LED1_ON (gpioe_virt->ODR |= (0x1 << 10)) //LED1点亮 #define LED1_OFF (gpioe_virt->ODR &= (~(0x1 << 10))) //LED1熄灭#define LED2_ON (gpiof_virt->ODR |= (0x1 << 10)) //LED2点亮 #define LED2_OFF (gpiof_virt->ODR &= (~(0x1 << 10))) //LED2熄灭#define LED3_ON (gpioe_virt->ODR |= (0x1 << 8)) //LED3点亮 #define LED3_OFF (gpioe_virt->ODR &= (~(0x1 << 8))) //LED3熄灭int myled_open(struct inode *inode, struct file *file) {printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0; }ssize_t myled_write(struct file *file, const char __user *ubuf, size_t size, loff_t *loff) {int ret;printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);//如果用户空间想写的大小256个字节,大于内核空间的大小128个字节,需要更正用户空间写的大小if(size > sizeof(kbuf)) size = sizeof(kbuf);ret = copy_from_user(kbuf,ubuf,size); //将用户空间的数据,写入到内核空间if(ret){printk("copy from user is error\n");return -EIO;}//kbuf[0] = 0 操作LED1 kbuf[0] = 1 操作LED2 kbuf[0] = 2 操作LED3//kbuf[1] = 0 LED熄灭 kbuf[1] = 1 LED点亮switch (kbuf[0]){case LED1: //操作LED1kbuf[1] == 0 ? LED1_OFF : LED1_ON;break;case LED2: //操作LED2kbuf[1] == 0 ? LED2_OFF : LED2_ON;break; case LED3: //操作LED3kbuf[1] == 0 ? LED3_OFF : LED3_ON;break; }return size; } int myled_close(struct inode *inode, struct file *file) {printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0; }//操作方法结构体 const struct file_operations fops = {.open = myled_open,.write = myled_write,.release = myled_close, };//入口函数 static int __init demo_init(void) { //注册字符设备驱动major = register_chrdev(0,CNAME,&fops);if(major < 0){printk("register chrdev is error\n");return -EIO;}printk("major = %d\n",major);//RCC_MP_AHB4ENSETR寄存器地址映射rcc_virt = ioremap(RCC_MP_AHB4ENSETR,4);if(rcc_virt == NULL){printk("rcc ioremap is error\n");return -EIO;}//GPIOE组寄存器地址映射gpioe_virt = ioremap(GPIOE,sizeof(gpio_t));if(gpioe_virt == NULL){printk("gpioe_virtr ioremap is error\n");return -EIO;}//GPIOF组寄存器地址映射gpiof_virt = ioremap(GPIOF,sizeof(gpio_t));if(gpiof_virt == NULL){printk("gpiof_virtr ioremap is error\n");return -EIO;}//LED1初始化//使能GPIOE组控制器 rcc_virt[4] = 1*rcc_virt |= (0x1 << 4);//设置PE10引脚为输出模式 MODER[21:20] = 01gpioe_virt->MODER &= (~(0x3 << 20));gpioe_virt->MODER |= (0x1 << 20);//设置PE10引脚输出低电平,LED1熄灭 ODR[10] = 0gpioe_virt->ODR &= (~(0x1 << 10));//LED2初始化//使能GPIOE组控制器 rcc_virt[5] = 1*rcc_virt |= (0x1 << 5);//设置PF10引脚为输出模式 MODER[21:20] = 01gpiof_virt->MODER &= (~(0x3 << 20));gpiof_virt->MODER |= (0x1 << 20);//设置PF10引脚输出低电平,LED2熄灭 ODR[10] = 0gpiof_virt->ODR &= (~(0x1 << 10)); //LED3初始化//设置PE8引脚为输出模式 MODER[17:16] = 01gpioe_virt->MODER &= (~(0x3 << 16));gpioe_virt->MODER |= (0x1 << 16);//设置PE8引脚输出低电平,LED3熄灭 ODR[8] = 0gpioe_virt->ODR &= (~(0x1 << 8));return 0; //函数的返回值 }//出口函数 static void __exit demo_exit(void) {iounmap(gpioe_virt);iounmap(gpiof_virt);iounmap(rcc_virt);//注销字符设备驱动unregister_chrdev(major,CNAME); }module_init(demo_init); //指定入口地址 module_exit(demo_exit); //指定出口地址 MODULE_LICENSE("GPL"); //许可证,遵循GPL协议
应用层程序:
#include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include "myled.h"int main(int argc,const char * argv[]) {int fd = -1;char buf[128] = "";fd = open("/dev/myled",O_RDWR); //打开if(fd == -1){perror("open is error\n");exit(1);}while(1){buf[0] = LED1; //操作LED1灯write(fd,buf,sizeof(buf)); //将用户空间的数据,写入内核空间buf[1] = 1; //LED1灯点亮write(fd,buf,sizeof(buf)); //将用户空间的数据,写入内核空间sleep(1);buf[1] = 0; //LED1灯熄灭write(fd,buf,sizeof(buf)); //将用户空间的数据,写入内核空间sleep(1);buf[0] = LED2; //操作LED2灯write(fd,buf,sizeof(buf)); //将用户空间的数据,写入内核空间buf[1] = 1; //LED2灯点亮write(fd,buf,sizeof(buf)); //将用户空间的数据,写入内核空间sleep(1);buf[1] = 0; //LED2灯熄灭write(fd,buf,sizeof(buf)); //将用户空间的数据,写入内核空间sleep(1);buf[0] = LED3; //操作LED3灯write(fd,buf,sizeof(buf)); //将用户空间的数据,写入内核空间buf[1] = 1; //LED3灯点亮write(fd,buf,sizeof(buf)); //将用户空间的数据,写入内核空间sleep(1);buf[1] = 0; //LED3灯熄灭write(fd,buf,sizeof(buf)); //将用户空间的数据,写入内核空间sleep(1);}close(fd);return 0; }