led.c

一个简单的字符设备的驱动--led的驱动,对于学习linux驱动有一定的帮助!

/* 
	the led driver for matrix v5
	date: 2007.03.16
	by jjj.
*/

//-------------------------------------

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/devfs_fs_kernel.h> 

#include <asm/hardware.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/rtc.h>
#include <asm/mach/time.h>
#include <asm/hardware/clock.h>
#include <asm/arch/regs-gpio.h> 

#define 		LED1		0x01
#define 		LED2		0x02
#define 		LED3		0x04
#define 		LED4		0x08

static int matrix_led_major = 0;
static unsigned char led_status = 0;

static void set_led_status(unsigned char status)
{
	unsigned char led_status_changed;
	led_status_changed = led_status ^ (status & 0x0F);
	led_status = status & 0x0F;

	if(led_status_changed != 0x00)
	{
		if(led_status_changed & LED1)
		{
			if(led_status & LED1)
				s3c2410_gpio_setpin(S3C2410_GPB7,0);
			else
				s3c2410_gpio_setpin(S3C2410_GPB7,1);
		}

		if(led_status_changed & LED2)
		{
			if(led_status & LED2)
				s3c2410_gpio_setpin(S3C2410_GPB8,0);
			else
				s3c2410_gpio_setpin(S3C2410_GPB8,1);
		}
	
		if(led_status_changed & LED3)
		{
			if(led_status & LED3)
				s3c2410_gpio_setpin(S3C2410_GPB9,0);
			else
				s3c2410_gpio_setpin(S3C2410_GPB9,1);
		}
	
		if(led_status_changed & LED4)
		{
			if(led_status & LED4)
				s3c2410_gpio_setpin(S3C2410_GPB10,0);
			else
				s3c2410_gpio_setpin(S3C2410_GPB10,1);
		}
	}
}

static int matrix_led_open(struct inode *inode,struct file *filp)
{
	return 0;
}

static int matrix_led_release(struct inode *inode,struct file *filp)
{
	return 0;
}

static ssize_t matrix_led_read(struct file *filp,char *buff,size_t count,loff_t *offp)
{
	copy_to_user(buff,(char *)&led_status,sizeof(unsigned char));
	return sizeof(unsigned char);
}

static ssize_t matrix_led_write(struct file *filp,const char *buff,size_t count,loff_t *offp)
{
	unsigned char status;
	if(count == 1)
	{
		if(copy_from_user(&status,buff,sizeof(unsigned char)))
			return -EFAULT;
		set_led_status(status);
		return sizeof(unsigned char);
	}
	else
		return -EFAULT;
}

static struct file_operations matrix_led_fops = { 
	.owner 	= THIS_MODULE, 
	.open   	= matrix_led_open,
	.read   	= matrix_led_read,
	.write	= matrix_led_write,
	.release	= matrix_led_release,
}; 

static int __init matrix_led_init(void)
{
   int ret;

   ret = register_chrdev(0,"led",&matrix_led_fops);
	if(ret < 0) 
	{
		printk("matrix_led: can't get major number\n");
		return ret;
	}
	matrix_led_major = ret;

	#ifdef CONFIG_DEVFS_FS
	ret = devfs_mk_cdev(MKDEV(matrix_led_major,0),S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP,"led");
	if(ret)
	{
		unregister_chrdev(matrix_led_major,"led"); 
		printk("matrix_led: can't make char device fo devfs\n");
		return ret;
	}
	#endif

	s3c2410_gpio_cfgpin(S3C2410_GPB7,S3C2410_GPB7_OUTP); 
	s3c2410_gpio_cfgpin(S3C2410_GPB8,S3C2410_GPB8_OUTP); 
	s3c2410_gpio_cfgpin(S3C2410_GPB9,S3C2410_GPB9_OUTP); 
	s3c2410_gpio_cfgpin(S3C2410_GPB10,S3C2410_GPB10_OUTP); 
	s3c2410_gpio_setpin(S3C2410_GPB7,1);
	s3c2410_gpio_setpin(S3C2410_GPB8,1);
	s3c2410_gpio_setpin(S3C2410_GPB9,1);
	s3c2410_gpio_setpin(S3C2410_GPB10,1);
	led_status = 0x00;

	printk("led: the matrix led initialized\n");
	return 0;
}

static void __exit matrix_led_exit(void)
{
	set_led_status(~(LED1 | LED2 | LED3 | LED4));
	#ifdef CONFIG_DEVFS_FS
		devfs_remove("led");
	#endif
	unregister_chrdev(matrix_led_major,"led");
	printk("led: the matrix led driver exit\n");
}

module_init(matrix_led_init);
module_exit(matrix_led_exit);

MODULE_ALIAS("matrix_led"); 
MODULE_DESCRIPTION("The Matrix LED Driver");
MODULE_AUTHOR("jjj.<[e-mail]>");
MODULE_LICENSE("GPL");