本文参考百度文库“linux驱动开发入门”点击打开链接和转载博文:点击打开链接。
一、基本知识
Linux设备驱动分为:字符设备、块设备和网络设备。原理图如下:
二、示例
示例主要转载自博客园的博客,见上。只是我采用的的Linux内核版本比那篇博文的新,有小许改动,粘贴代码如下:
内核版本:
ry@ubuntu:/$ uname -a
Linux ubuntu 3.16.0-30-generic #40~14.04.1-Ubuntu SMP Thu Jan 15 17:43:14 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
文件:hello_mod.c
- /*
- * =====================================================================================
- *
- * Filename: hello.c
- *
- * Description: hello_mod
- *
- * Version: 1.0
- * Created: 01/28/2011 05:07:55 PM
- * Revision: none
- * Compiler: gcc
- *
- * Author: Tishion (shion), [email protected]
- * Company: LIM
- *
- * =====================================================================================
- */
- #include <linux/module.h>
- #include <linux/init.h>
- #include <linux/kernel.h>
- #include <linux/fs.h>
- #include <linux/uaccess.h>
- #include <linux/semaphore.h>
- #include <linux/cdev.h>
- #include <linux/device.h>
- #include <linux/ioctl.h>
- #include <linux/slab.h>
- #include <linux/errno.h>
- #include <linux/string.h>
- #include “hello_mod_ioctl.h”
- #define MAJOR_NUM 250
- #define MINOR_NUM 0
- #define IN_BUF_LEN 256
- #define OUT_BUF_LEN 512
- MODULE_AUTHOR(”Tishion”);
- MODULE_DESCRIPTION(”Hello_mod driver by tishion”);
- static struct class * hello_class;
- static struct cdev hello_cdev;
- static dev_t devnum = 0;
- static char * modname = “hello_mod”;
- static char * devicename = “hello”;
- static char * classname = “hello_class”;
- static int open_count = 0;
- static struct semaphore sem;
- static DEFINE_SPINLOCK(spin);
- static char * inbuffer = NULL;
- static char * outbuffer = NULL;
- static lang_t langtype;
- static int hello_mod_open(struct inode *, struct file *);
- static int hello_mod_release(struct inode *, struct file *);
- static ssize_t hello_mod_read(struct file *, char *, size_t, loff_t *);
- static ssize_t hello_mod_write(struct file *, const char *, size_t, loff_t *);
- static long hello_mod_ioctl(struct file *, unsigned int, unsigned long);
- struct file_operations hello_mod_fops =
- {
- .owner = THIS_MODULE,
- .open = hello_mod_open,
- .read = hello_mod_read,
- .write = hello_mod_write,
- .unlocked_ioctl = hello_mod_ioctl,
- .release = hello_mod_release,
- };
- static int hello_mod_open(struct inode *inode, struct file *pfile)
- {
- printk(”+hello_mod_open()!/n”);
- spin_lock(&spin);
- if(open_count)
- {
- spin_unlock(&spin);
- return -EBUSY;
- }
- open_count++;
- spin_unlock(&spin);
- printk(”-hello_mod_open()!/n”);
- return 0;
- }
- static int hello_mod_release(struct inode *inode, struct file *pfile)
- {
- printk(”+hello_mod_release()!/n”);
- open_count–;
- printk(”-hello_mod_release()!/n”);
- return 0;
- }
- static ssize_t hello_mod_read(struct file *pfile, char *user_buf, size_t len, loff_t *off)
- {
- printk(”+hello_mod_read()!/n”);
- if(down_interruptible(&sem))
- {
- return -ERESTARTSYS;
- }
- memset(outbuffer, 0, OUT_BUF_LEN);
- printk(” +switch()/n”);
- switch(langtype)
- {
- case english:
- printk(” >in case: english/n”);
- sprintf(outbuffer, ”Hello! %s.”, inbuffer);
- break;
- case chinese:
- printk(” >in case: chinese/n”);
- sprintf(outbuffer, ”你好! %s.”, inbuffer);
- break;
- case pinyin:
- printk(” >in case: pinyin/n”);
- sprintf(outbuffer, ”ni hao! %s.”, inbuffer);
- break;
- default:
- printk(” >in case: default/n”);
- break;
- }
- printk(” -switch()/n”);
- if(copy_to_user(user_buf, outbuffer, len))
- {
- up(&sem);
- return -EFAULT;
- }
- up(&sem);
- printk(”-hello_mod_read()!/n”);
- return 0;
- }
- static ssize_t hello_mod_write(struct file *pfile, const char *user_buf, size_t len, loff_t *off)
- {
- printk(”+hello_mod_write()!/n”);
- if(down_interruptible(&sem))
- {
- return -ERESTARTSYS;
- }
- if(len > IN_BUF_LEN)
- {
- printk(”Out of input buffer/n”);
- return -ERESTARTSYS;
- }
- if(copy_from_user(inbuffer, user_buf, len))
- {
- up(&sem);
- return -EFAULT;
- }
- up(&sem);
- printk(”-hello_mod_write()!/n”);
- return 0;
- }
- static long hello_mod_ioctl(struct file *pfile, unsigned int cmd, unsigned long arg)
- {
- int err = 0;
- printk(”+hello_mod_ioctl()!/n”);
- printk(” +switch()/n”);
- switch(cmd)
- {
- case HELLO_IOCTL_RESETLANG:
- printk(” >in case: HELLO_IOCTL_RESETLANG/n”);
- langtype = english;
- break;
- case HELLO_IOCTL_GETLANG:
- printk(” >in case: HELLO_IOCTL_GETLANG/n”);
- err = copy_to_user((int *)arg, &langtype, sizeof(int));
- break;
- case HELLO_IOCTL_SETLANG:
- printk(” >in case: HELLO_IOCTL_SETLANG/n”);
- err = copy_from_user(&langtype,(int *)arg, sizeof(int));
- break;
- default:
- printk(” >in case: default/n”);
- err = ENOTSUPP;
- break;
- }
- printk(” -switch()/n”);
- printk(”-hello_mod_ioctl()!/n”);
- return err;
- }
- static int __init hello_mod_init(void)
- {
- int result;
- printk(”+hello_mod_init()!/n”);
- devnum = MKDEV(MAJOR_NUM, MINOR_NUM);
- result = register_chrdev_region(devnum, 1, modname);
- if(result < 0)
- {
- printk(”hello_mod : can’t get major number!/n”);
- return result;
- }
- cdev_init(&hello_cdev, &hello_mod_fops);
- hello_cdev.owner = THIS_MODULE;
- hello_cdev.ops = &hello_mod_fops;
- result = cdev_add(&hello_cdev, devnum, 1);
- if(result)
- printk(”Failed at cdev_add()”);
- hello_class = class_create(THIS_MODULE, classname);
- if(IS_ERR(hello_class))
- {
- printk(”Failed at class_create().Please exec [mknod] before operate the device/n”);
- }
- else
- {
- device_create(hello_class, NULL, devnum,NULL, devicename);
- }
- open_count = 0;
- langtype = english;
- inbuffer = (char *)kmalloc(IN_BUF_LEN, GFP_KERNEL);
- outbuffer = (char *)kmalloc(OUT_BUF_LEN, GFP_KERNEL);
- sema_init(&sem, 1);
- printk(”-hello_mod_init()!/n”);
- return 0;
- }
- static void __exit hello_mod_exit(void)
- {
- printk(”+hello_mod_exit!/n”);
- kfree(inbuffer);
- kfree(outbuffer);
- cdev_del(&hello_cdev);
- device_destroy(hello_class, devnum);
- class_destroy(hello_class);
- unregister_chrdev_region(devnum, 1);
- printk(”-hello_mod_exit!/n”);
- return ;
- }
- module_init(hello_mod_init);
- module_exit(hello_mod_exit);
- MODULE_LICENSE(”GPL”);
/* * ===================================================================================== * * Filename: hello.c * * Description: hello_mod * * Version: 1.0 * Created: 01/28/2011 05:07:55 PM * Revision: none * Compiler: gcc * * Author: Tishion (shion), [email protected] * Company: LIM * * ===================================================================================== */