河北网站建设电话,中国国防建设网站,建设一个百度百科类网站,国外哪些网站做产品推广比较好1 ioctl操作实现
对相应设备做指定的控制操作#xff08;各种属性的设置获取等等#xff09;
long xxx_ioctl (struct file *filp, unsigned int cmd, unsigned long arg);
功能#xff1a;对相应设备做指定的控制操作#xff08;各种属性的设置获取等等#xff09;
参数…1 ioctl操作实现
对相应设备做指定的控制操作各种属性的设置获取等等
long xxx_ioctl (struct file *filp, unsigned int cmd, unsigned long arg);
功能对相应设备做指定的控制操作各种属性的设置获取等等
参数filp指向open产生的struct file类型的对象表示本次ioctl对应的那次opencmd用来表示做的是哪一个操作arg和cmd配合用的参数
返回值成功为0失败-1
cmd组成 dirdirectionioctl 命令访问模式属性数据传输方向占据 2 bit可以为 IOC_NONE、IOC_READ、IOC_WRITE、IOC_READ | _IOC_WRITE分别指示了四种访问模式无数据、读数据、写数据、读写数据 typedevice type设备类型占据 8 bit在一些文献中翻译为 “幻数” 或者 “魔数”可以为任意 char 型字符例如 ‘a’、’b’、’c’ 等等其主要作用是使 ioctl 命令有唯一的设备标识 nrnumber命令编号/序数占据 8 bit可以为任意 unsigned char 型数据取值范围 0~255如果定义了多个 ioctl 命令通常 从 0 开始编号递增 size涉及到 ioctl 函数 第三个参数 arg 占据 13bit 或者 14bit体系相关arm 架构一般为 14 位指定了 arg 的数据类型及长度如果在驱动的 ioctl 实现中不检查通常可以忽略该参数
#define _IOC(dir,type,nr,size) (((dir)_IOC_DIRSHIFT)| \((type)_IOC_TYPESHIFT)| \((nr)_IOC_NRSHIFT)| \((size)_IOC_SIZESHIFT))
//用于解码ioctl数字
/* used to create numbers */
// 定义不带参数的 ioctl 命令
#define _IO(type,nr) _IOC(_IOC_NONE,(type),(nr),0)
//定义带读参数的ioctl命令copy_to_user size为类型名
#define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
//定义带写参数的 ioctl 命令copy_from_user size为类型名
#define _IOW(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
//定义带读写参数的 ioctl 命令 size为类型名
#define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
//用于解码ioctl数字
/* used to decode ioctl numbers */
#define _IOC_DIR(nr) (((nr) _IOC_DIRSHIFT) _IOC_DIRMASK)
#define _IOC_TYPE(nr) (((nr) _IOC_TYPESHIFT) _IOC_TYPEMASK)
#define _IOC_NR(nr) (((nr) _IOC_NRSHIFT) _IOC_NRMASK)
#define _IOC_SIZE(nr) (((nr) _IOC_SIZESHIFT) _IOC_SIZEMASK)
头文件位置 1.1 示例
mychar.h
#ifndef MY_CHAR_H
#define MY_CHAR_H#include asm/ioctl.h#define MY_CHAR_MAGIC k#define MYCHAR_IOCTL_GET_MAXLEN _IOR(MY_CHAR_MAGIC,1,int*)
#define MYCHAR_IOCTL_GET_CURLEN _IOR(MY_CHAR_MAGIC,2,int*)#endifmychar.c
#include linux/module.h
#include linux/kernel.h
#include linux/fs.h
#include linux/cdev.h
#include asm/uaccess.h#include mychar.h#define BUF_LEN 100int major 11;
int minor 0;
int mychar_num 1;//新建结构体类型
struct mychar_dev
{struct cdev mydev;char mydef_buf[BUF_LEN]; //相当于结构体的私有变量int curlen; //相当于结构体的私有变量
};struct mychar_dev gmydev;int mychar_open(struct inode *pnode, struct file *pfile)
{//利用private_data私有变量来指向全局变量结构体地址pfile-private_data (void*)(container_of(pnode-i_cdev,struct mychar_dev,mydev));printk(mychar_open is called\n);return 0;
}int mychar_close(struct inode *pnode, struct file *pfile)
{printk(mychar_close is called\n);return 0;
}ssize_t mychar_read(struct file *filp, char __user *pbuf, size_t count, loff_t *ppos)
{int ret 0;int size 0;//获取全家变量结构体地址struct mychar_dev *pmydev (struct mychar_dev *)filp-private_data;if(count pmydev-curlen){size pmydev-curlen;}else{size count;}//将内核空间中的数据复制到用户空间ret copy_to_user(pbuf,pmydev-mydef_buf,size);if(ret){printk(copy_to_user failed\n);return -1;}//读完之后把后面的内容再拷贝过来同时更新curlenmemcpy(pmydev-mydef_buf,pmydev-mydef_bufsize,pmydev-curlen - size);pmydev-curlen pmydev-curlen - size;return size;}ssize_t mychar_write (struct file *filp, const char __user *pbuf, size_t count, loff_t *ppos)
{int size 0;int ret 0;//获取全家变量结构体地址struct mychar_dev *pmydev (struct mychar_dev *)filp-private_data;if(count BUF_LEN - pmydev-curlen){size BUF_LEN - pmydev-curlen;}else{size count;}//将用户空间中的数据复制到内核空间中ret copy_from_user(pmydev-mydef_buf pmydev-curlen, pbuf, size);if(ret){printk(copy_from_user failed\n);return -1;}//更新curlenpmydev-curlen pmydev-curlen size;return size;
}long mychar_ioctl(struct file *filp, unsigned int cmd,unsigned long arg)
{int __user *pret (int *)arg;int maxlen BUF_LEN;int ret 0;struct mychar_dev *pmydev (struct mychar_dev *)filp-private_data;switch(cmd){case MYCHAR_IOCTL_GET_MAXLEN:ret copy_to_user(pret,maxlen,sizeof(int));if(ret){printk(copy_to_user MAXLEN failed\n);return -1;}break;case MYCHAR_IOCTL_GET_CURLEN:ret copy_to_user(pret,pmydev-curlen,sizeof(int));if(ret){printk(copy_to_user CURLEN failed\n);return -1;}break;default:printk(The cmd is unknow\n);return -1;}return 0;
}//结构体初始化:部分变量赋值初始化
struct file_operations myops {.owner THIS_MODULE,.open mychar_open,.release mychar_close,.read mychar_read,.write mychar_write,.unlocked_ioctl mychar_ioctl
};int mychar_init(void)
{int ret 0;dev_t devno MKDEV(major, minor);/* 申请设备号 */ret register_chrdev_region(devno, mychar_num, mychar);if (ret) {ret alloc_chrdev_region(devno, minor, mychar_num, mychar);if (ret) {printk(get devno failed\n);return -1;}major MAJOR(devno); // 容易遗漏注意}/* 给struct cdev对象指定操作函数集 */cdev_init(gmydev.mydev, myops);/* 将 struct cdev对象添加到内核对应的数据结构里 */gmydev.mydev.owner THIS_MODULE;cdev_add(gmydev.mydev, devno, mychar_num);return 0;
}void __exit mychar_exit(void)
{dev_t devno MKDEV(major, minor);cdev_del(gmydev.mydev);unregister_chrdev_region(devno, mychar_num);
}//表示支持GPL的开源协议
MODULE_LICENSE(GPL);module_init(mychar_init);
module_exit(mychar_exit);Makefile
ifeq ($(KERNELRELEASE),)ifeq ($(ARCH),arm)
KERNELDIR ? /home/linux/Linux_4412/kernel/linux-3.14
ROOTFS ? /opt/4412/rootfs
else
KERNELDIR ? /lib/modules/$(shell uname -r)/build
endif
PWD : $(shell pwd)modules:$(MAKE) -C $(KERNELDIR) M$(PWD) modulesmodules_install:$(MAKE) -C $(KERNELDIR) M$(PWD) modules INSTALL_MOD_PATH$(ROOTFS) modules_installclean:rm -rf *.o *.ko .*.cmd *.mod.* modules.order Module.symvers .tmp_versionselse
CONFIG_MODULE_SIGn
obj-m mychar.oendiftestmychar_app.c
#include sys/types.h
#include sys/stat.h
#include fcntl.h
#include unistd.h
#include sys/ioctl.h#include mychar.h
#include stdio.hint main(int argc,char *argv[])
{int fd -1;char buf[8] ;int max 0;int cur 0;if(argc 2){printf(The argument is too few\n);return 1;}fd open(argv[1],O_RDWR);if(fd 0){printf(open %s failed\n,argv[1]);return 2;}ioctl(fd,MYCHAR_IOCTL_GET_MAXLEN,max);printf(max len is %d\n,max);write(fd,hello,6);ioctl(fd,MYCHAR_IOCTL_GET_CURLEN,cur);printf(cur len is %d\n,cur);read(fd,buf,8);printf(buf%s\n,buf);close(fd);fd -1;return 0;
}编译执行测试获取设备参数 2 printk
//日志级别
#define KERN_EMERG 0 /* system is unusable */
#define KERN_ALERT 1 /* action must be taken immediately */
#define KERN_CRIT 2 /* critical conditions */
#define KERN_ERR 3 /* error conditions */
#define KERN_WARNING 4 /* warning conditions */
#define KERN_NOTICE 5 /* normal but significant condition */
#define KERN_INFO 6 /* informational */
#define KERN_DEBUG 7 /* debug-level messages */
用法printk(KERN_INFO....,....)printk(KERN_INFOHello World); printk(6Hello World) printk(6Hello World)
dmesg --levelemerg,alert,crit,err,warn,notice,info,debug
dmesg中7个级别对应printk中7个级别
#define HELLO_DEBUG
#undef PDEBUG
#ifdef HELLO_DEBUG
#define PDEBUG(fmt, args...) printk(KERN_DEBUG fmt, ##args)
#else
#define PDEBUG(fmt, args...)
#endif
3 多个次设备的支持
linux支持一个具体的设备同时占用1个主设备号多个次设备号的情况这种情况主要是根据cdev_add中参数来决定的一般是1需要多个次设备号改写参数另一种情况是针对一份驱动代码对应多个同类次设备主设备号一样次设备不一样的设备
本节讲得是第二个情况必须有一个struct cdev来代表它
cdev_initcdev.owner赋值cdev_add
以上三个操作对每个具体设备都要进行
3.1 示例
multimychar.c
#include linux/module.h
#include linux/kernel.h
#include linux/fs.h
#include linux/cdev.h
#include asm/uaccess.h#include mychar.h#define BUF_LEN 100
#define MYCHAR_DEV_CNT 3int major 11;
int minor 0;
int mychar_num MYCHAR_DEV_CNT; //支持多个设备//新建结构体类型
struct mychar_dev
{struct cdev mydev;char mydef_buf[BUF_LEN]; //相当于结构体的私有变量int curlen; //相当于结构体的私有变量
};struct mychar_dev gmydev_arr[MYCHAR_DEV_CNT]; //多个设备实现创建结构体数组int mychar_open(struct inode *pnode, struct file *pfile)
{//利用private_data私有变量来指向全局变量结构体地址pfile-private_data (void*)(container_of(pnode-i_cdev,struct mychar_dev,mydev));printk(mychar_open is called\n);return 0;
}int mychar_close(struct inode *pnode, struct file *pfile)
{printk(mychar_close is called\n);return 0;
}ssize_t mychar_read(struct file *filp, char __user *pbuf, size_t count, loff_t *ppos)
{int ret 0;int size 0;//获取全家变量结构体地址struct mychar_dev *pmydev (struct mychar_dev *)filp-private_data;if(count pmydev-curlen){size pmydev-curlen;}else{size count;}//将内核空间中的数据复制到用户空间ret copy_to_user(pbuf,pmydev-mydef_buf,size);if(ret){printk(copy_to_user failed\n);return -1;}//读完之后把后面的内容再拷贝过来同时更新curlenmemcpy(pmydev-mydef_buf,pmydev-mydef_bufsize,pmydev-curlen - size);pmydev-curlen pmydev-curlen - size;return size;}ssize_t mychar_write (struct file *filp, const char __user *pbuf, size_t count, loff_t *ppos)
{int size 0;int ret 0;//获取全家变量结构体地址struct mychar_dev *pmydev (struct mychar_dev *)filp-private_data;if(count BUF_LEN - pmydev-curlen){size BUF_LEN - pmydev-curlen;}else{size count;}//将用户空间中的数据复制到内核空间中ret copy_from_user(pmydev-mydef_buf pmydev-curlen, pbuf, size);if(ret){printk(copy_from_user failed\n);return -1;}//更新curlenpmydev-curlen pmydev-curlen size;return size;
}long mychar_ioctl(struct file *filp, unsigned int cmd,unsigned long arg)
{int __user *pret (int *)arg;int maxlen BUF_LEN;int ret 0;struct mychar_dev *pmydev (struct mychar_dev *)filp-private_data;switch(cmd){case MYCHAR_IOCTL_GET_MAXLEN:ret copy_to_user(pret,maxlen,sizeof(int));if(ret){printk(copy_to_user MAXLEN failed\n);return -1;}break;case MYCHAR_IOCTL_GET_CURLEN:ret copy_to_user(pret,pmydev-curlen,sizeof(int));if(ret){printk(copy_to_user CURLEN failed\n);return -1;}break;default:printk(The cmd is unknow\n);return -1;}return 0;
}//结构体初始化:部分变量赋值初始化
struct file_operations myops {.owner THIS_MODULE,.open mychar_open,.release mychar_close,.read mychar_read,.write mychar_write,.unlocked_ioctl mychar_ioctl
};int mychar_init(void)
{int ret 0;int i 0;dev_t devno MKDEV(major, minor);/* 申请设备号 */ret register_chrdev_region(devno, mychar_num, mychar);if (ret) {ret alloc_chrdev_region(devno, minor, mychar_num, mychar);if (ret) {printk(get devno failed\n);return -1;}major MAJOR(devno); // 容易遗漏注意}for(i 0;i MYCHAR_DEV_CNT;i){devno MKDEV(major,minori); //设备号需要重新组合/* 给struct cdev对象指定操作函数集 */cdev_init(gmydev_arr[i].mydev, myops);/* 将 struct cdev对象添加到内核对应的数据结构里 */gmydev_arr[i].mydev.owner THIS_MODULE;cdev_add(gmydev_arr[i].mydev, devno, 1); //这里需要填1}return 0;
}void __exit mychar_exit(void)
{dev_t devno MKDEV(major, minor);int i 0;for(i 0; i MYCHAR_DEV_CNT; i ){cdev_del(gmydev_arr[i].mydev);}unregister_chrdev_region(devno, mychar_num);
}//表示支持GPL的开源协议
MODULE_LICENSE(GPL);module_init(mychar_init);
module_exit(mychar_exit);mychar.h(未修改)
#ifndef MY_CHAR_H
#define MY_CHAR_H#include asm/ioctl.h#define MY_CHAR_MAGIC k#define MYCHAR_IOCTL_GET_MAXLEN _IOR(MY_CHAR_MAGIC,1,int*)
#define MYCHAR_IOCTL_GET_CURLEN _IOR(MY_CHAR_MAGIC,2,int*)#endiftestmychar_app.c(维修工)
#include sys/types.h
#include sys/stat.h
#include fcntl.h
#include unistd.h
#include sys/ioctl.h#include mychar.h
#include stdio.hint main(int argc,char *argv[])
{int fd -1;char buf[8] ;int max 0;int cur 0;if(argc 2){printf(The argument is too few\n);return 1;}fd open(argv[1],O_RDWR);if(fd 0){printf(open %s failed\n,argv[1]);return 2;}ioctl(fd,MYCHAR_IOCTL_GET_MAXLEN,max);printf(max len is %d\n,max);write(fd,hello,6);ioctl(fd,MYCHAR_IOCTL_GET_CURLEN,cur);printf(cur len is %d\n,cur);read(fd,buf,8);printf(buf%s\n,buf);close(fd);fd -1;return 0;
}Makefile
ifeq ($(KERNELRELEASE),)ifeq ($(ARCH),arm)
KERNELDIR ? /home/linux/Linux_4412/kernel/linux-3.14
ROOTFS ? /opt/4412/rootfs
else
KERNELDIR ? /lib/modules/$(shell uname -r)/build
endif
PWD : $(shell pwd)modules:$(MAKE) -C $(KERNELDIR) M$(PWD) modulesmodules_install:$(MAKE) -C $(KERNELDIR) M$(PWD) modules INSTALL_MOD_PATH$(ROOTFS) modules_installclean:rm -rf *.o *.ko .*.cmd *.mod.* modules.order Module.symvers .tmp_versionselse
CONFIG_MODULE_SIGn
obj-m mychar.oendif编译运行
