myadc.c

s3c2410平台下ADC数模转换驱动的源码

/****************Copyright (c)***************************
** File name:		myadc.c
** Created by:		junzuyu
** Created date:		2008-10-9
** Version:			1.0
*********************************************************/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/version.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <asm/hardware.h>
#include <asm/delay.h>
#include <asm/uaccess.h>
#include <linux/ioport.h>
#include <linux/cdev.h>
#include <asm-arm/arch-s3c2410/regs-adc.h>
#include <asm/io.h>

static int adc_open(struct inode *inode,struct file *filp);
static int adc_release(struct inode *inode,struct file *filp);
static ssize_t adc_read(struct file *filp,char *buffer,size_t count,loff_t *ppos);

static int __init s3c2410_adc_init(void);
static void __exit s3c2410_adc_eixt(void);

module_init(s3c2410_adc_init);
module_exit(s3c2410_adc_eixt);

MODULE_LICENSE("Proprietary");
MODULE_DESCRIPTION("Shanghai YuanHong Development Co.,LTD.");
MODULE_SUPPORTED_DEVICE("utu-linux2.6.x s3c2440  spi_ad");
MODULE_AUTHOR("junzuyu");


#define DEVICE_NAME "myadc"
#define ADCMINOR 0
static int ADCMajor=0;
//#define ADCMINOR 0
unsigned long rADCCON_save;
static void __iomem *base_addr;
volatile unsigned long prescaler;

struct adc_dev_t{
	struct cdev cdev;
	unsigned long value;
} adc_dev;

#define REQCNT 100 
#define ADC_FREQ 2500000				// adc freq
#define LOOP 10000

static struct file_operations myadc_fops= {
    .owner  =   THIS_MODULE,
    .open   =   adc_open,
    .read   =   adc_read,
    .release    =   adc_release,
};

static int adc_open(struct inode *inode,struct file *filp) {

	rADCCON_save=ioread32(base_addr+S3C2410_ADCCON);//保存原来的设置，退出时还原
	printk("ADCCON=%lx\n",rADCCON_save);
	
	prescaler=ADC_FREQ;								//预分频值
	printk("ADC conv. freq. = %luHz\n",prescaler);
	
	prescaler = 50000000/ADC_FREQ -1;				//PCLK:50.7MHz
	printk("PCLK/ADC_FREQ - 1 = %lu\n",prescaler);   //prescaler=19
	printk("myadc open ok!\n");

	return 0;
}

static int adc_release(struct inode *inode,struct file *filp)
{
	iowrite32(rADCCON_save,base_addr+S3C2410_ADCCON);
	printk("myadc release ok!\n");
	return 0;
}

static ssize_t adc_read(struct file *filp,char *buffer,size_t count,loff_t *ppos)
{
	unsigned long addata;
	unsigned long temp;
	static int ch = 1;

	temp=(1<<14)|(prescaler<<6)|(ch<<3);
	printk("temp=%lx\n",temp);
	
	iowrite32(temp,base_addr+S3C2410_ADCCON);
	printk("Set CH if same %lx\n",(1<<14)|(prescaler<<6)|(ch<<3));
	printk("before is ok!\n");
	
	iowrite32((ioread32(base_addr+S3C2410_ADCCON)|0x1), base_addr+S3C2410_ADCCON);  //start ADC
	printk("start ADC %x\n",(ioread32(base_addr+S3C2410_ADCCON)));

	while(ioread32(base_addr+S3C2410_ADCCON) & 0x1);	//check if Enable_start is low
	while((ioread32(base_addr+S3C2410_ADCCON) & 0x8000));	//check if EC(End of Conversion) flag is high
	//printk
	//printk("I will gave you a adc data %x\n",(readl(base_addr+S3C2410_ADCDAT0) & 0x3ff));
	
	//iowrite32(rADCCON_save,base_addr+S3C2410_ADCCON);//还原
	addata=(ioread32(base_addr+S3C2410_ADCDAT0) & 0x3ff);
	copy_to_user(buffer,(unsigned long *)&addata,sizeof(unsigned long));
	
	return 0;
}



static int __init s3c2410_adc_init(void){
		int ret;
		dev_t devno=MKDEV(ADCMajor,0);
		
		cdev_init(&adc_dev.cdev,&myadc_fops);
		adc_dev.cdev.owner=THIS_MODULE;
		
		if(ADCMajor){
			register_chrdev_region(devno,1,DEVICE_NAME);
		}else{
			alloc_chrdev_region(&devno,0,1,DEVICE_NAME);
			ADCMajor=MAJOR(devno);
		}
		ret=cdev_add(&adc_dev.cdev,devno,1);
		printk("ADCMajor=%d\n",ADCMajor);
		

#ifdef  CONFIG_DEVFS_FS
 	devfs_mk_cdev(MKDEV(ADCMajor,ADCNMINOR),S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP,DEVICE_NAME);
#endif

    	printk(DEVICE_NAME" initialized\n");
    
	if(request_mem_region(S3C2410_PA_ADC,0x20,DEVICE_NAME)==NULL){
		printk("request_mem_region error\n");
		return(0);
	}
    base_addr=ioremap(S3C2410_PA_ADC,0x20);//映射ADC的控制寄存器
    if (base_addr == NULL) {
      printk(KERN_ERR "Failed to remap register block\n");
			return -ENOMEM;
    }
	printk("base_addr=%lx\n",base_addr);
    return 0;
}
    
static void __exit s3c2410_adc_eixt(void){
	dev_t devno;
	
	devno = MKDEV(ADCMajor,0);

	iounmap(base_addr);
	release_mem_region(S3C2410_PA_ADC,0x20);
	
 #ifdef CONFIG_DEVFS_FS
    devfs_remove(DEVICE_NAME);  
 #endif
 
	unregister_chrdev_region(devno,1);
	cdev_del(&adc_dev.cdev);
}