高级字符驱动程序操作---增加ioctl功能

/*How to use: *# echo "" > /var/log/messages //clear file *# insmod pipe.ko *# mknod /dev/myp c 250 0 * # make test_ioctl //creat test_ioctl to test the ioctl of our module * # ./test_ioctl * Then you can see * * [1]count is 1023 * buf's content is :wwwww............ * [2]count is 1023 * old content is w * buf's content is: xxxx............. */#include <linux/module.h> #include <linux/moduleparam.h>#include <linux/kernel.h> /* printk(), min() */#include <linux/slab.h> /* kmalloc() */#include <linux/fs.h> /* everything... */#include <linux/proc_fs.h> #include <linux/errno.h> /* error codes */#include <linux/types.h> /* size_t */#include <linux/fcntl.h> #include <linux/poll.h> #include <linux/cdev.h>#include <asm/uaccess.h> #include <linux/wait.h>/* wait_event_interruptible() *///#include <asm/semaphore.h> /* down_interruptible() up() */#include <linux/semaphore.h>#include <linux/sched.h>//error: ‘TASK_INTERRUPTIBLE’ undeclared #define MYDEBUG 1//turn on debug info printing switch#define BUF_SIZE 1024 //pipe's buffer size/* ioctl */#define MY_P_IOC_MAGIC'p'//use 'p' as magic number#define MY_P_IOCRESET_IO(MY_P_IOC_MAGIC, 0)//clear content of device buffer#define MY_P_IOFILL_IOW(MY_P_IOC_MAGIC, 1, char)//fill device buffer with argument value#define MY_P_IOXCH_IOWR(MY_P_IOC_MAGIC,2, char*) //read out the charactor from buffer,and filled with new value#define MY_P_IOC_MAXNR2// print debug infomation#define print_debug_info() /do {/printk (KERN_NOTICE " %s called success /n", __func__);/}while (0)struct my_pipe {wait_queue_head_t inq, outq; // read and write queuechar* buffer, *end; //begin of buffer,end of bufferint buffersize;// sizeof bufferint nreaders, nwriters; // number of openings for r/w char* rp, *wp;// where to read, where to writestruct fasync_struct *async_r_queue; //asynchronous reader queue//struct fasync_struct *async_w_queue; // asynchronous writer queuestruct semaphore sem;//mutual exclusion semaphorestruct cdev cdev;// Char device structure};int mydev_major, mydev_minor;//record the device major and minor numberstruct my_pipe * my_p_dev; // pointer to our deviceint my_p_buf_size = BUF_SIZE; // size of my_pipe's buffer//declaration of functionsvoid my_p_clearup_module (void);int my_p_setup_cdev(struct my_pipe* my_p_dev, dev_t devno);int my_p_init_module (void);static int my_p_open(struct inode *inode, struct file *filp);static int my_p_release(struct inode *inode, struct file *filp);static ssize_t my_p_write(struct file *filp, const char __user *buf, size_t count,loff_t *f_pos);static ssize_t my_p_read (struct file *filp, char __user *buf, size_t count,loff_t *f_pos);int my_p_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg);struct file_operations my_p_fops = {.owner = THIS_MODULE,.llseek = no_llseek,.read = my_p_read,.write = my_p_write,.poll = 0,.ioctl = my_p_ioctl,.open = my_p_open,.release = my_p_release,.fasync = 0,};int my_p_init_module (void){int result = 0;dev_t dev;result = alloc_chrdev_region(&dev, 0/*minor*/, 1/*dev nums*/,"my_pipe");mydev_major = MAJOR(dev);//store the major and minor number of our devicemydev_minor = MINOR(dev); if (result < 0) { printk (KERN_WARNING "my_pipe: alloc major error!/n");return result;}#ifdef MYDEBUG else { printk (KERN_WARNING "my_pipe: major is %d/n", mydev_major);} #endif // allocate device structuremy_p_dev = kmalloc (sizeof(struct my_pipe), GFP_KERNEL);if (!my_p_dev) {printk (KERN_WARNING "my_pipe: alloc struct my_pipe error!/n");goto fail;}//init our device itemsmemset (my_p_dev, 0, sizeof(my_p_dev));init_waitqueue_head(&my_p_dev->inq);init_waitqueue_head(&my_p_dev->outq);init_MUTEX(&my_p_dev->sem);my_p_dev->buffer = NULL;//This is very importantif (my_p_setup_cdev(my_p_dev, dev) < 0) {printk (KERN_NOTICE "my_p_setup_cdev called error/n");goto fail;}#ifdef MYDEBUGprint_debug_info(); // current function success #endifreturn 0;fail:my_p_clearup_module();return result;}int my_p_setup_cdev(struct my_pipe* my_p_dev, dev_t devno){int result;cdev_init(&my_p_dev->cdev, &my_p_fops);my_p_dev->cdev.owner = THIS_MODULE;my_p_dev->cdev.ops = &my_p_fops;result = cdev_add (&my_p_dev->cdev, devno, 1);printk(KERN_NOTICE "result is %d/n", result);if (result < 0) {printk (KERN_NOTICE "my_p_dev setup error! /n");return -EFAULT;}//#ifdef MYDEGUGprint_debug_info();//success//#endifreturn result;}/* free the device mem and free the device struct */void my_p_clearup_module (void){dev_t devno = MKDEV(mydev_major, mydev_minor);//The queue memery has been freed by my_p_releasecdev_del (&my_p_dev->cdev);// unregister charactor number regionunregister_chrdev_region(devno, 1); //here we should free the device structkfree (my_p_dev);//#ifdef MYDEGUGprint_debug_info();//success //#endif}static int my_p_open(struct inode *inode, struct file *filp){struct my_pipe *dev;dev = container_of(inode->i_cdev, struct my_pipe, cdev);//get and //save device's pointerfilp->private_data = dev;if (down_interruptible(&dev->sem))return -ERESTARTSYS;if (!dev->buffer) {dev->buffer = kmalloc(my_p_buf_size, GFP_KERNEL);//allocate the bufferif(!dev->buffer){up(&dev->sem);return -ENOMEM;}printk(KERN_NOTICE "mem allocate success/n");//}dev->buffersize = my_p_buf_size;dev->end = dev->buffer + dev->buffersize;dev->rp = dev->buffer;dev->wp = dev->buffer;}if (filp->f_mode & FMODE_READ)dev->nreaders++;if (filp->f_mode & FMODE_WRITE)dev->nwriters++;up(&dev->sem);//#ifdef MYDEGUGprint_debug_info();//success //#endif//return 0;return nonseekable_open(inode, filp);//don't want the seekable file descriptor}static int my_p_release(struct inode *inode, struct file *filp){struct my_pipe *dev;dev = filp->private_data; // get device pointer/* remove this filp from the asynchronously notified filp's *///my_p_fasync(-1, filp, 0);//??????????????????????????????????down(&dev->sem);if (filp->f_mode & FMODE_READ)dev->nreaders--;if (filp->f_mode & FMODE_WRITE)dev->nwriters--;if ((dev->nreaders + dev->nwriters) == 0) {kfree(dev->buffer);dev->buffer = NULL;printk(KERN_NOTICE "mem release succes/n");}up(&dev->sem);//#ifdef MYDEGUGprint_debug_info();//success //#endifreturn 0;}/* Full return 1, or return 0 */int is_full(struct my_pipe* dev){char* p = NULL;p = dev->wp;p ++;if (p > dev->end)p = dev->buffer;if (p == dev->rp)return 1;//fullreturn 0;//not full}static ssize_t my_p_write(struct file *filp, const char __user *buf, size_t count,loff_t *f_pos){struct my_pipe* dev = filp->private_data;int max_num = 0;printk(KERN_NOTICE "%s is entered/n", __func__);if (down_interruptible(&dev->sem)){return -ERESTARTSYS;}while (is_full(dev) == 1) {up(&dev->sem);if (filp->f_flags & O_NONBLOCK)return -EAGAIN;if (wait_event_interruptible(dev->inq,is_full(dev) != 0))return -ERESTARTSYS; // signal: tell the fs layer to handle it/* otherwise loop, but first reacquire the lock */if (down_interruptible(&dev->sem))return -ERESTARTSYS;}//ok , now there is place to write tomax_num = (int)(dev->rp - dev->wp -1 + my_p_buf_size) % my_p_buf_size;printk(KERN_NOTICE "max_num is %d/t count is %d", max_num, (int)count);count= min(count, (size_t)max_num);if (copy_from_user(dev->wp, buf, count)) {up(&dev->sem);printk(KERN_NOTICE "copy error in %s/n", __func__);return -EFAULT;}dev->wp += count;if (dev->wp == dev->end - 1)//pointer wrapteddev->wp = dev->buffer;up(&dev->sem);wake_up_interruptible(&dev->outq); // blocked in read() and select() //#ifdef MYDEGUGprint_debug_info();//success//#endifreturn count;}static ssize_t my_p_read (struct file *filp, char __user *buf, size_t count,loff_t *f_pos){struct my_pipe* dev = filp->private_data;int max_num = 0;printk(KERN_NOTICE "%s is entered/n", __func__);if (down_interruptible(&dev->sem)){return -ERESTARTSYS;}printk(KERN_NOTICE "%s before while/n", __func__); while (dev->rp == dev->wp) { // nothing to read up(&dev->sem); // release the lock if (filp->f_flags & O_NONBLOCK)return -EAGAIN;if (wait_event_interruptible(dev->outq, (dev->rp != dev->wp))) return -ERESTARTSYS; // signal: tell the fs layer to handle it/* otherwise loop, but first reacquire the lock */if (down_interruptible(&dev->sem)) return -ERESTARTSYS; }printk(KERN_NOTICE "%s after while/n", __func__);/* ok, data is there, return something */max_num = (dev->wp - dev->rp + my_p_buf_size) % my_p_buf_size;count = min((size_t)max_num, count);if (copy_to_user(buf, dev->rp, count)) {up(&dev->sem);return -EFAULT;}//update the read pointerdev->rp += count; if (dev->rp == dev->end - 1)dev->rp = dev->buffer;up(&dev->sem);/* finally, awake any writer */wake_up_interruptible(&dev->inq); // blocked in write() and select()//#ifdef MYDEGUGprint_debug_info();//success//#endif return count;}int my_p_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg){int err = 0;int retval = 0;struct my_pipe* dev = filp->private_data;char swap = '/0'; /* * extract the type and number bitfields, and don't decode * wrong cmds: return ENOTTY (inappropriate ioctl) before access_ok() */printk(KERN_NOTICE "%s called start.../n", __func__);if (_IOC_TYPE(cmd) != MY_P_IOC_MAGIC) return -ENOTTY;if (_IOC_NR(cmd) > MY_P_IOC_MAXNR) return -ENOTTY;if (_IOC_DIR(cmd) & _IOC_READ) err = !access_ok(VERIFY_WRITE, (void __user *)arg, _IOC_SIZE(cmd)); else if (_IOC_DIR(cmd) & _IOC_WRITE) err = !access_ok(VERIFY_READ, (void __user *)arg, _IOC_SIZE(cmd));if (err) return -EFAULT;if (down_interruptible(&dev->sem))return -ERESTARTSYS;switch (cmd) {case MY_P_IOCRESET://clear content of device bufferif (dev->buffer) {dev->wp = dev->buffer;dev->rp = dev->buffer;}break;case MY_P_IOFILL://fill device buffer with argument valueprintk(KERN_NOTICE "%s called in switch/n", __func__);if (dev->buffer) {printk(KERN_NOTICE "parameter is %c/n", (char)arg);memset(dev->buffer, (char)arg, dev->buffersize - 1);dev->wp = dev->end - 1;dev->rp = dev->buffer;printk(KERN_NOTICE "dev->rp's content is %c /ndev->wp's content is %c /n", *dev->rp, *dev->wp);break;}retval = -EINVAL;break;case MY_P_IOXCH://read out the charactor from buffer,and filled with new valueif (dev->buffer) {swap = *(dev->buffer);memset(dev->buffer, *((char*)arg), dev->buffersize -1);put_user(swap, (char*)arg);break;}retval = -EINVAL;break;default:retval = -ENOTTY;}up(&dev->sem);return retval;}MODULE_LICENSE("Dual BSD/GPL");MODULE_AUTHOR("[e-mail]");module_init(my_p_init_module); module_exit(my_p_clearup_module);

------------- 用户空间测试程序 ----------------------

 

//test_ioctl.c#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <unistd.h>#include <sys/ioctl.h>#include <errno.h>#include <linux/ioctl.h>#define MY_P_IOC_MAGIC 'p' //use 'p' as magic number#define MY_P_IOCRESET _IO(MY_P_IOC_MAGIC, 0)//clear content of device buffer#define MY_P_IOFILL _IOW(MY_P_IOC_MAGIC, 1, char)//fill device buffer with argument value#define MY_P_IOXCH _IOWR(MY_P_IOC_MAGIC,2, char*) //read out the charactor from buffer,and filled with new value int main(void){int fd = -1;char ch = 'w';char buf[1024] = "";int count = 0; fd = open("/dev/myp", O_RDWR | O_NONBLOCK);if (fd < 0) {fprintf(stderr, "open error:%s/n", strerror(errno));}if (write(fd, "I love Linux", 12) < 0) {fprintf(stderr, "write error:%s/n", strerror(errno));}if (ioctl(fd, MY_P_IOFILL, ch) < 0) {fprintf(stderr, "ioctl error:%s/n", strerror(errno));exit(1);}if ((count = read(fd, buf, 1023)) < 0) {fprintf(stderr, "read after set error:%s", strerror(errno));exit(1);}buf[1023] = '/0';printf("[1]count is %d/nbuf's content is :%s/n", count, buf);ch = 'x';if (ioctl(fd, MY_P_IOXCH, &ch) < 0) {fprintf(stderr, "ioctl error:%s/n", strerror(errno));exit(1);} if ((count = read(fd, buf, 1023)) < 0) {fprintf(stderr, "read after set error:%s", strerror(errno));exit(1);}buf[1023] = '/0';printf("[2]count is %d /nold content is %c /nbuf's content is: %s/n", count, ch, buf);return 0;}