adc8.c

为优龙公司的2410开发板写的一个的AD采样驱动程序

/**************************************************************
	adc8.c
	linux driver example  
	author: 
	date:   
***************************************************************/

#ifndef __KERNEL__
#  define __KERNEL__
#endif
#ifndef MODULE
#  define MODULE
#endif

#include<linux/iobuf.h>
#include<linux/major.h>
#include<asm/uaccess.h>
#include<asm/hardware.h>
#include<asm/arch/cpu_s3c2410.h>
#include<asm/io.h>
#include<linux/vmalloc.h>

#include <linux/config.h>
#include <linux/module.h>
#include <linux/devfs_fs_kernel.h>

#include <linux/init.h>
#include <linux/kernel.h>   /* printk() */
#include <linux/slab.h>   /* kmalloc() */
#include <linux/fs.h>       /* everything... */
#include <linux/errno.h>    /* error codes */
#include <linux/types.h>    /* size_t */
#include <linux/proc_fs.h>
#include <linux/fcntl.h>    /* O_ACCMODE */
#include <linux/poll.h>    /* COPY_TO_USER */
#include <asm/system.h>     /* cli(), *_flags */

#define DRIVER_AUTHOR "shuyan ma <[e-mail]>"
#define DRIVER_DESC   "A sample driver for adc8"
#define DEVICE_NAME		"adc8"
#define adc8_MAJOR  223
#define adc8_MINOR  0
static int MAX_BUF_LEN=1024;
static unsigned char drv_buf[2];
typedef union {
	unsigned int inv;
	struct {
		unsigned char xmsb;
		 unsigned char xlsb;
	}ch;
}xunion;
xunion readbuf;
 
/*************************************************************************************/
static ssize_t  adc8_read(struct file *filp, char *buffer, size_t count, loff_t *ppos)
{
        if(count > MAX_BUF_LEN) count=MAX_BUF_LEN;
	ADCCON|=0x01;		//start ADC
	while(ADCCON & 0x1);       //check if Enable_start is low
	while(!(ADCCON & 0x8000)); //check if EC(End of Conversion) flag is high
        readbuf.inv=(int)ADCDAT0 & 0x3ff;
        drv_buf[0]=readbuf.ch.xlsb;
        drv_buf[1]=readbuf.ch.xmsb;
        copy_to_user(buffer,drv_buf,count);
        printk("user read %x from adc8 driver\n",readbuf.inv);
        return count;
}

/*************************************************************************************/
static int adc8_ioctl(struct inode *inode, struct file *file, 
                 unsigned int cmd, unsigned long arg)
{
	static unsigned int preScaler;
	static int preCh=-1;
	printk("adc8 ioctl runing\n");
	switch(cmd){
		case 0:
			preScaler=HZ/4/arg-1;
			printk("setup ADC_Freqency is: %d\n",preScaler);
			//preScaler=PCLK/arg-1;
			break;
		case 1:
			printk("select ADC channel\n");
			if(preCh!=arg)
			{
				ADCCON=(1<<14)|(preScaler<<6)|(arg<<3);
				preCh=arg;
			}
			break;
		default:
			printk("error cmd number\n");break;
	}
	return 0;
}
/*************************************************************************************/
static int adc8_open(struct inode *inode, struct file *file)
{
	MOD_INC_USE_COUNT;
	printk("adc8 device open sucess!\n");
	return 0;
}
/*************************************************************************************/
static int  adc8_release(struct inode *inode, struct file *filp)
{
	MOD_DEC_USE_COUNT;
	printk("adc8 device release\n");
	return 0;
}

/*************************************************************************************/
static struct file_operations adc8_fops = {
	owner:	THIS_MODULE,
	read:	adc8_read,
	ioctl:	adc8_ioctl,
	open:	adc8_open,
	release:	adc8_release,
};
/*************************************************************************************/
static int __init adc8_init(void)
{

	int  result;
    	SET_MODULE_OWNER(&adc8_fops);
    	result = register_chrdev(adc8_MAJOR, "adc8", &adc8_fops);
	if(result)
	{
		printk("fail to register adc8\n");
		return -1;
	}

	printk(DEVICE_NAME " initialized\n");
	return 0;
}

/*************************************************************************************/
static void __exit  adc8_exit(void)
{
	unregister_chrdev(adc8_MAJOR, "adc8");
	printk(DEVICE_NAME " unloaded\n");
}

/*************************************************************************************/
module_init(adc8_init);
module_exit(adc8_exit);

/*
 * Get rid of taint message by declaring code as GPL.
 */
MODULE_LICENSE("GPL");
                                                                                
/*
 * Or with defines, like this:
 */
MODULE_AUTHOR(DRIVER_AUTHOR);   /* Who wrote this module? */
MODULE_DESCRIPTION(DRIVER_DESC);        /* What does this module do */
                                                                                
/*
 *  This module uses /dev/testdevice.  The MODULE_SUPPORTED_DEVICE macro might
 *  be used in the future to help automatic configuration of modules, but is
 *  currently unused other than for documentation purposes.
 */
MODULE_SUPPORTED_DEVICE("adc8");