s3c2410-watchdog.c

s3c2410-watchdog 源码 arm902 linux字符设备驱动

#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>

#include <linux/miscdevice.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/spinlock.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/vmalloc.h>

#include <linux/Def.h>
#include <linux/2410.h>

#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/hardware.h>
#include <asm/arch/cpu_s3c2410.h>


#ifdef CONFIG_PM
#include <linux/pm.h>
#endif

#define WATCHDOG_MAJOR 193 
#define DEVICE_NAME	"watchdog"
devfs_handle_t devfs_watchdog;

int wdflag = 1;


static ssize_t watchdog_read(struct file *filp, char *buffer, size_t count, loff_t *ppos)
{

	return count;
}


static ssize_t watchdog_write (struct file *file, const char *buffer, size_t user_len, loff_t *offset)
{
       //printk("wdflag = %d  \n" , wdflag);
       if ( wdflag == 1 )
         {
           printk("wdflag = 1 \n");
           WTCON = 0xff39;
           wdflag = 0;
         }
       WTCNT = 0xffff;
        
       return user_len;

}

static int watchdog_open(struct inode *inode, struct file *filp)
{
	MOD_INC_USE_COUNT; //计数器加一
	return 0;
}

static int watchdog_release(struct inode *inode, struct file *filp)
{
	MOD_DEC_USE_COUNT; //计数器减一
	return 0;
}

static struct file_operations s3c2410watchdog_fops = {
	owner	:	THIS_MODULE,
	read	:	watchdog_read,
	open	:	watchdog_open,
	write	:	watchdog_write,
	release	:	watchdog_release,
};

static int __init watchdog_init(void)
{
        int ret , flags;        
        
	local_irq_save (flags);  //关闭所有的中断 并保存当前的状态
        
        WTDAT = 0xffff;
        WTCNT = 0xffff;
        WTCON = 0xff18;

	local_irq_restore(flags);  //打开中断,并恢复状态
    
        ret=register_chrdev (WATCHDOG_MAJOR,DEVICE_NAME,&s3c2410watchdog_fops);
	if (ret<0)
		{
			return ret;
		}
	

	devfs_watchdog = devfs_register(NULL,"watchdog",DEVFS_FL_DEFAULT,WATCHDOG_MAJOR,                              0, S_IFCHR |S_IRUSR |S_IWUSR |S_IRGRP |S_IWGRP,                                 &s3c2410watchdog_fops, NULL);
        
        

	return 0;

}

static void __exit watchdog_exit(void)
{

	devfs_unregister(devfs_watchdog);

}

module_init(watchdog_init);
module_exit(watchdog_exit);