demo.c

《linux驱动程序设计从入门到精通》一书中所有的程序代码含驱动和相应的应用程序

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2007, 2010 fengGuojin([e-mail])
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/slab.h>	
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/seq_file.h>
#include <linux/cdev.h>
#include <linux/version.h>
#include <linux/vmalloc.h>
#include <linux/delay.h>
#include <linux/ctype.h>
#include <linux/pagemap.h>

#include "demo.h"

MODULE_AUTHOR("fgj");
MODULE_LICENSE("Dual BSD/GPL");

#define SIMPLE_TIMER_DELAY 2*HZ//2Second

struct DEMO_dev *DEMO_devices;
static unsigned char demo_inc=0;
static int Condition = 1;

static struct timer_list simple_timer;
static void simple_timer_handler(unsigned long data);

static void simple_timer_handler( unsigned long data)
{
	simple_timer.expires 	= jiffies + SIMPLE_TIMER_DELAY;
	simple_timer.function	= &simple_timer_handler;
	add_timer (&simple_timer);
	if(Condition<10)
	{
		printk("the %d times\n",Condition);
		Condition++;
	}
	else
	{
		printk("delete timer\n");
		del_timer(&simple_timer);
	}
	return ;
}

int DEMO_open(struct inode *inode, struct file *filp)
{
	struct DEMO_dev *dev; /* device information */

	demo_inc++;

	dev = container_of(inode->i_cdev, struct DEMO_dev, cdev);
	filp->private_data = dev; /* for other methods */

	return 0;          /* success */
}

int DEMO_release(struct inode *inode, struct file *filp)
{
	demo_inc--;
	return 0;
}

ssize_t DEMO_read(struct file *filp, char __user *buf, size_t count,loff_t *f_pos)
{
	return 0;
}

ssize_t DEMO_write(struct file *filp, const char __user *buf, size_t count,loff_t *f_pos)
{
	return 0;
}

int DEMO_ioctl(struct inode *inode, struct file *filp,unsigned int cmd, unsigned long arg)
{
    return 0;
}

loff_t DEMO_llseek(struct file *filp, loff_t off, int whence)
{
	return 0;
}

struct file_operations DEMO_fops = {
	.owner =    THIS_MODULE,
	.llseek =   DEMO_llseek,
	.read =     DEMO_read,
	.write =    DEMO_write,
	.ioctl =    DEMO_ioctl,
	.open =     DEMO_open,
	.release =  DEMO_release,
};

/*******************************************************
                MODULE ROUTINE
*******************************************************/
void DEMO_cleanup_module(void)
{
	dev_t devno = MKDEV(DEMO_MAJOR, DEMO_MINOR);

	/* Get rid of our char dev entries */
	if (DEMO_devices) 
	{
		cdev_del(&DEMO_devices->cdev);
		kfree(DEMO_devices);
	}

	/* cleanup_module is never called if registering failed */
	unregister_chrdev_region(devno,1);
}

int DEMO_init_module(void)
{
	int result;
	dev_t dev = 0;

	dev = MKDEV(DEMO_MAJOR, DEMO_MINOR);
	result = register_chrdev_region(dev, 1, "DEMO");
	if (result < 0) 
	{
		printk(KERN_WARNING "DEMO: can't get major %d\n", DEMO_MAJOR);
		return result;
	}

	//allocate the devices 
	DEMO_devices = kmalloc(sizeof(struct DEMO_dev), GFP_KERNEL);
	if (!DEMO_devices)
	{
		result = -ENOMEM;
		goto fail;  /* Make this more graceful */
	}
	memset(DEMO_devices, 0, sizeof(struct DEMO_dev));

	init_MUTEX(&DEMO_devices->sem);
	cdev_init(&DEMO_devices->cdev, &DEMO_fops);
	DEMO_devices->cdev.owner = THIS_MODULE;
	DEMO_devices->cdev.ops = &DEMO_fops;
	result = cdev_add (&DEMO_devices->cdev, dev, 1);
	if(result)
	{
		printk(KERN_NOTICE "Error %d adding DEMO\n", result);
		goto fail;
	}

	/* Register timer */
	init_timer(&simple_timer);
	simple_timer.function = &simple_timer_handler;
	simple_timer.expires = jiffies + SIMPLE_TIMER_DELAY;
	add_timer (&simple_timer);
	return 0; /* succeed */

fail:
	DEMO_cleanup_module();
	return result;
}

module_init(DEMO_init_module);
module_exit(DEMO_cleanup_module);