accelerometer.c

这是基于在linux系统下基于PXA255平台的加速度计的驱动程序以及加速度计的测试程序。

/*
 * Accelerometer demo driver for Linux
 *
 * Copyright (C) 2002 Alvin Tang <[e-mail]>
 * Copyright (C) 2007 Socrates <[e-mail]>
 *
 * This driver allows you to access the contents of accelerometer sensor on
 * the Sitsang board.
 *
 * The device file for Accelerometer is "/dev/acce". You can create this file
 * handly by 
 * 		mknod /dev/acce c 10 241
 *
 * Example code for reading data in user space:
 * -------------------------------------------------------------------
 * 		struct acce_point{
 * 			unsigned int x;
 * 			unsigned int y;
 * 		}tmp;
 * 		
 *		int main(int argc, char **argv)
 *		{
 *			....
 *			
 * 			fd=open("/dev/acce", O_RDONLY);
 * 			....
 * 			
 * 			read(fd, &tmp, sizeof(acce_point));
 * 			....
 * 			
 * 			close(fd); //close device file
 * 		}
 * --------------------------------------------------------------------
 * 		
 */

#define SITSANG_ACCE_VERSION		"1.1"
#define SITSANG_ACCE_MINOR	241

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/fcntl.h>
#include <linux/init.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/hardware.h>
#include <asm/arch/pxa-regs.h>
#include <asm/arch/sitsang.h>
#include <asm/system.h>
#include <linux/delay.h>

static struct acce_point{
	unsigned int x;
	unsigned int y;
}acce_status;

static ssize_t acce_read(struct file * file,
	char * buf, size_t count, loff_t *ppos )
{
	ssize_t ret = 0;

	
	while ( ret + sizeof (struct acce_point) <= count )  {
		acce_status.x = SITSANG_AXHR_RD & 0x0000ffff;
		acce_status.y = SITSANG_AYHR_RD & 0x0000ffff;
		if (copy_to_user(buf + ret, &acce_status, sizeof (struct acce_point))){
			printk("copy to user failed\n");
			return -EFAULT;
		}
		
		ret += sizeof (struct acce_point);
	}
	
	return ret;
}

static int acce_open( struct inode *inode, struct file *file )
{
	SITSANG_PCR_RW |= SITSANG_PCR_ACC_ON | SITSANG_PCR_PER_ON;
	mdelay(100);

	return 0;
}

static int acce_release( struct inode *inode, struct file *file )
{
	SITSANG_PCR_RW &= ~SITSANG_PCR_ACC_ON;
	return 0;
}


static struct file_operations acce_fops = {
	.owner =	THIS_MODULE,
	.read =		acce_read,
	.open =		acce_open,
	.release =	acce_release,
};

static struct miscdevice acce_dev = {
	SITSANG_ACCE_MINOR,
	"accelerometer",
	&acce_fops
};


static int __init acce_init(void)
{
	int ret;

	ret = misc_register( &acce_dev );
	if (ret) {
		printk(KERN_ERR "acce: can't misc_register on minor=%d\n", SITSANG_ACCE_MINOR);
		goto out;
	}
	ret = 0;
	printk(KERN_INFO "Sitsang Accelerometer Sensor driver v" SITSANG_ACCE_VERSION "\n");
out:
	return( ret );
}

static void __exit acce_cleanup_module (void)
{
	misc_deregister( &acce_dev );
}

module_init(acce_init);
module_exit(acce_cleanup_module);

MODULE_AUTHOR("Alvin Tang <[e-mail]>");
MODULE_DESCRIPTION("Accelerometer Sensor Driver for Sitsang Board");
MODULE_LICENSE("GPL");