ioctl函数实现灯\蜂鸣器和风扇的工作
- 相关知识点
-
- udev创建设备节点的原理
- linux操作系统中ioctl函数的使用
- ioctl函数的功能码
- 相关API
-
- 自动创建设备节点相关API
- ioctl的相关API
- 代码实现
-
相关知识点
udev创建设备节点的原理
linux操作系统中ioctl函数的使用
linux内核有意将设备的功能控制和数据的读写分成不同的函数完成，比如串口驱动，将串口的波特率、数据位宽等信息通过ioctl来实现，串口的数据收发通过read/write来实现
ioctl函数的功能码
上面的方向指的是从内核到用户还是从用户到内核，以用户作为第一人称
如果想要得到上面的表述某种功能的命名码，需要通过一些宏定义实现
#define _IOC(dir,type,nr,size) \
(((dir) << _IOC_DIRSHIFT) | \
((type) << _IOC_TYPESHIFT) | \
((nr) << _IOC_NRSHIFT) | \
((size) << _IOC_SIZESHIFT))
dir<<30|size<<16|type<<8|nr<<0
#define _IO(type,nr) _IOC(_IOC_NONE,(type),(nr),0)
#define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),sizeof(size))
#define _IOW(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
#define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
//如果想要得到一个具有某种特定含义的功能码只需要_IO\_IOW\_IOR\_IOWR就可以得到
ex:以灯的开和关为例
#define LED_ON _IOW('a',1,int)
LED_ON 01 00000000000100 01100001 00000001
#define LED_OFF _IOW('a',0,int)
LED_OFF 01 00000000000100 01100001 00000000
相关API
自动创建设备节点相关API
#include
1.向上提交目录
struct class *class_create(struct module *owner, const char *name)
功能：向上提交目录
参数：
owner:THIS_MODULE/和编译器相关的宏，这个宏是struct module类型，这个结构体
里面指定了入口和出口
name:目录名
返回值：成功返回目录结构体指针，失败返回指向错误码的指针（void *）(-error)
关于错误码的解释：
IS_ERR()：根据地址区间的位置判断错误，IS_ERR判断目录所在的地址区间是否在最顶层的4K空间（预留空间）中，如果在就表示创建错误
static inline long __must_check IS_ERR(const void *ptr)
{
return IS_ERR_VALUE((unsigned long)ptr);
}
IS_ERR_VALUE(x) unlikely((x)（
2.向上提交设备节点
struct device *device_create(struct class *class, struct device *parent,
dev_t devt, void *drvdata, const char *fmt, ...)
功能：提交节点信息
参数：
class:class_create创建产生的句柄
parent:NULL
devt:设备号
MKDEV(major,minor);
MAJOR(dev)
MINOR(dev)
drvdata：NULL
fmt：节点名
3.销毁节点
void device_destroy(struct class *class, dev_t devt)
功能：销毁设备节点
参数：
class:class_create创建的句柄
devt:设备号
4.销毁目录
void class_destroy(struct class *cls)
功能：销毁目录
参数：目录指针（句柄）
ioctl的相关API
系统调用函数：
#include
int ioctl(int fd, unsigned long request, ...);
功能：通过功能码实现设备的控制
参数：
fd:设备文件的文件描述符
request:功能码
...:可以写参数，也可以不写，写参数的时候写地址
返回值：成功返回0，失败返回错误码
An ioctl() request has encoded in it whether the argument is an in parameter or out
parameter, and the size of the argument argp in bytes.
struct file_operations {
long (*unlocked_ioctl) (struct file *, unsigned int cmd, unsigned long arg);
}；
代码实现
tim.c文件
#include
#include
#include
#include
#include
#include
#include
#include"myled.h"
#define CNAME "mytim"
int major;
char kbuf[128]={};
gpio_t *vir_tim1;
gpio_t *vir_tim4;
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;
}
ssize_t mycdev_read(struct file *file, char __user *ubuf, size_t size, loff_t *loff)
{
int ret;
if(size>sizeof(kbuf))
size=sizeof(kbuf);
ret=copy_to_user(ubuf,kbuf,size);
if(ret)
{
printk("数据从内核向用户拷贝失败\n");
return -EIO;
}
return size;
}
ssize_t mycdev_write(struct file *file, const char __user *ubuf, size_t size, loff_t *loff)
{
int ret;
if(size>sizeof(kbuf))
size=sizeof(kbuf);
ret=copy_from_user(kbuf,ubuf,size);
if(ret)
{
printk("数据从内核向用户拷贝失败\n");
return -EIO;
}
return size;
}
long ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
int ret,which;
switch(cmd)
{
case TimON:
ret=copy_from_user(&which,(void *)arg,sizeof(int));
if(ret)
{
printk("用户向内核拷贝数据失败\n");
return -EIO;
}
switch(which)
{
case TIM1:
vir_tim1->ODR |= (1<<9);
break;
case TIM4:
vir_tim4->ODR |= (1<<6);
break;
}
break;
case TimOFF:
ret=copy_from_user(&which,(void *)arg,sizeof(int));
if(ret)
{
printk("用户向内核拷贝数据失败\n");
return -EIO;
}
switch(which)
{
case TIM1:
vir_tim1->ODR &= ~(1<<9);
break;
case TIM4:
vir_tim4->ODR &= ~(1<<6);
break;
}
break;
default:
printk("功能码错误\n");
break;
}
return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{
printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
return 0;
}
struct file_operations fops=
{
.open=mycdev_open,
.read=mycdev_read,
.write=mycdev_write,
.unlocked_ioctl=ioctl,
.release=mycdev_close,
};
int all_tim_init(void)
{
vir_rcc=ioremap(PHY_RCC_ADDR,4);
if(vir_rcc==NULL)
{
printk("vir_rcc 映射失败\n");
return -ENOMEM;
}
printk("vir_rcc 映射成功\n");
vir_tim1=ioremap(PHY_TIM1_ADDR,sizeof(gpio_t));
if(vir_tim1==NULL)
{
printk("vir_tim1 映射失败\n");
return -ENOMEM;
}
printk("vir_tim1 映射成功\n");
vir_tim4=ioremap(PHY_TIM4_ADDR,sizeof(gpio_t));
if(vir_tim4==NULL)
{
printk("vir_tim4 映射失败\n");
return -ENOMEM;
}
printk("vir_tim4 映射成功\n");
vir_tim1->MODER &= ~(3<<18);
vir_tim1->MODER |= (1<<18);
vir_tim1->ODR &=~(1<<9);
printk("____%d_\n",__LINE__);
vir_tim4->MODER &= ~(3<<12);
vir_tim4->MODER |= (1<<12);
vir_tim1->ODR &=~(1<<6);
printk("____%d_\n",__LINE__);
(*vir_rcc) |= (1<<4);
(*vir_rcc) |= (1<<1);
printk("____%d_\n",__LINE__);
return 0;
}
static int __init demo_init(void)
{
major=register_chrdev(0,CNAME,&fops);
if(major<0)
{
printk("字符设备驱动注册失败\n");
return major;
}
printk("字符设备驱动注册成功major=%d\n",major);
cls=class_create(THIS_MODULE,"TIM");
if(IS_ERR(cls))
{
printk("向上提交目录失败\n");
return PTR_ERR(cls);
}
printk("向上提交目录成功\n");
dev=device_create(cls,NULL,MKDEV(major,0),NULL,"mytim");
if(IS_ERR(dev))
{
printk("创建节点失败\n");
return PTR_ERR(dev);
}
printk("创建节点成功\n");
all_tim_init();
return 0;
}
static void __exit demo_exit(void)
{
device_destroy(cls,MKDEV(major,0));
class_destroy(cls);
iounmap(vir_tim1);
iounmap(vir_tim4);
iounmap(vir_rcc);
unregister_chrdev(major,CNAME);
}
module_init(demo_init);
module_exit(demo_exit);
MODULE_LICENSE("GPL");
测试文件
#include
#include
#include
#include
#include
#include
#include
#include"myled.h"
#define CNAME "mytim"
int major;
char kbuf[128]={};
gpio_t *vir_tim1;
gpio_t *vir_tim4;
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;
}
ssize_t mycdev_read(struct file *file, char __user *ubuf, size_t size, loff_t *loff)
{
int ret;
if(size>sizeof(kbuf))
size=sizeof(kbuf);
ret=copy_to_user(ubuf,kbuf,size);
if(ret)
{
printk("数据从内核向用户拷贝失败\n");
return -EIO;
}
return size;
}
ssize_t mycdev_write(struct file *file, const char __user *ubuf, size_t size, loff_t *loff)
{
int ret;
if(size>sizeof(kbuf))
size=sizeof(kbuf);
ret=copy_from_user(kbuf,ubuf,size);
if(ret)
{
printk("数据从内核向用户拷贝失败\n");
return -EIO;
}
return size;
}
long ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
int ret,which;
switch(cmd)
{
case TimON:
ret=copy_from_user(&which,(void *)arg,sizeof(int));
if(ret)
{
printk("用户向内核拷贝数据失败\n");
return -EIO;
}
switch(which)
{
case TIM1:
vir_tim1->ODR |= (1<<9);
break;
case TIM4:
vir_tim4->ODR |= (1<<6);
break;
}
break;
case TimOFF:
ret=copy_from_user(&which,(void *)arg,sizeof(int));
if(ret)
{
printk("用户向内核拷贝数据失败\n");
return -EIO;
}
switch(which)
{
case TIM1:
vir_tim1->ODR &= ~(1<<9);
break;
case TIM4:
vir_tim4->ODR &= ~(1<<6);
break;
}
break;
default:
printk("功能码错误\n");
break;
}
return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{
printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
return 0;
}
struct file_operations fops=
{
.open=mycdev_open,
.read=mycdev_read,
.write=mycdev_write,
.unlocked_ioctl=ioctl,
.release=mycdev_close,
};
int all_tim_init(void)
{
vir_rcc=ioremap(PHY_RCC_ADDR,4);
if(vir_rcc==NULL)
{
printk("vir_rcc 映射失败\n");
return -ENOMEM;
}
printk("vir_rcc 映射成功\n");
vir_tim1=ioremap(PHY_TIM1_ADDR,sizeof(gpio_t));
if(vir_tim1==NULL)
{
printk("vir_tim1 映射失败\n");
return -ENOMEM;
}
printk("vir_tim1 映射成功\n");
vir_tim4=ioremap(PHY_TIM4_ADDR,sizeof(gpio_t));
if(vir_tim4==NULL)
{
printk("vir_tim4 映射失败\n");
return -ENOMEM;
}
printk("vir_tim4 映射成功\n");
vir_tim1->MODER &= ~(3<<18);
vir_tim1->MODER |= (1<<18);
vir_tim1->ODR &=~(1<<9);
printk("____%d_\n",__LINE__);
vir_tim4->MODER &= ~(3<<12);
vir_tim4->MODER |= (1<<12);
vir_tim1->ODR &=~(1<<6);
printk("____%d_\n",__LINE__);
(*vir_rcc) |= (1<<4);
(*vir_rcc) |= (1<<1);
printk("____%d_\n",__LINE__);
return 0;
}
static int __init demo_init(void)
{
major=register_chrdev(0,CNAME,&fops);
if(major<0)
{
printk("字符设备驱动注册失败\n");
return major;
}
printk("字符设备驱动注册成功major=%d\n",major);
cls=class_create(THIS_MODULE,"TIM");
if(IS_ERR(cls))
{
printk("向上提交目录失败\n");
return PTR_ERR(cls);
}
printk("向上提交目录成功\n");
dev=device_create(cls,NULL,MKDEV(major,0),NULL,"mytim");
if(IS_ERR(dev))
{
printk("创建节点失败\n");
return PTR_ERR(dev);
}
printk("创建节点成功\n");
all_tim_init();
return 0;
}
static void __exit demo_exit(void)
{
device_destroy(cls,MKDEV(major,0));
class_destroy(cls);
iounmap(vir_tim1);
iounmap(vir_tim4);
iounmap(vir_rcc);
unregister_chrdev(major,CNAME);
}
module_init(demo_init);
module_exit(demo_exit);
MODULE_LICENSE("GPL");
tim.h
#ifndef __MYLED_H__
#define __MYLED_H__
typedef struct{
volatile unsigned int MODER;
volatile unsigned int OTYPER;
volatile unsigned int OSPEEDR;
volatile unsigned int PUPDR;
volatile unsigned int IDR;
volatile unsigned int ODR;
volatile unsigned int BSRR;
}gpio_t;
#define PHY_RCC_ADDR 0X50000A28
#define PHY_TIM1_ADDR 0X50006000
#define PHY_TIM4_ADDR 0X50003000
enum TIM
{
TIM1=1,
TIM4
};
#define TIM_ON _IO('a',1)
#define TIM_OFF _IO('a',0)
#define TimON _IOW('a',1,int)
#define TimOFF _IOW('a',0,int)
#endif
