s3c2440_adc.c

s3c2440 A/D转换驱动代码

/*
 * s3c2440_adc  
 *  
 * Author: SeonKon Choi <[e-mail]> 
 * Date  : $Date: 2003/01/20 14:24:49 $  
 * 
 * $Revision: 1.1.2.6 $ 
 * 
    2004-6-14 add a device by threewater<[e-mail]> 
 
   Fri Dec 03 2002 SeonKon Choi <[e-mail]> 
   - initial 
 
   modify by lxm<[e-mail]> 2009-02-16
 * 
 * This file is subject to the terms and conditions of the GNU General Public 
 * License.  See the file COPYING in the main directory of this archive 
 * for more details. 
 */  
 
#include <linux/module.h>
#include <linux/fs.h>           /* everything... */
#include <linux/cdev.h>
#include <linux/interrupt.h>    /* request_irq() */
#include <asm/arch/regs-adc.h>
#include <asm/hardware/clock.h>
#include <asm/io.h>
#include <asm/uaccess.h>        /* copy_to_user() */
#include "s3c2440_adc.h"   

#undef DEBUG   
#define DEBUG   
#ifdef DEBUG   
#define DPRINTK(x...) {printk(__FUNCTION__);printk("(%d): ",__LINE__);printk(x);}   
#else   
#define DPRINTK(x...) (void)(0)   
#endif   
  
#define VERSION_STRING  "ADC driver for s3c2440"
#define DEVICE_NAME "s3c2440_adc"   

#define ADC_CTL_BASE 0x58000000 /* 定义ADC寄存器基地址 */  
#define S3C2440ADC_MAJOR 240    /* 预设的S3C2440ADC的主设备号 */

static int s3c2440adc_major = S3C2440ADC_MAJOR;

struct s3c2440adc_dev {  
    struct cdev cdev;		/* cdev结构体 */
    struct semaphore lock;	/* 信号量 */
    wait_queue_head_t wait;	/* 定义等待队列头 */ 
    int channel;		/* 通道号 */  
    int prescale;		/* 预分频系数 */  
};  

struct s3c2440adc_dev s3c2440adc_dev;   /* 物理地址映射成虚拟地址后的基地址指针 */
struct s3c2440adc_dev *s3c2440adc_devp; /*设备结构体指针*/

static void __iomem *base_addr;         /* 物理地址映射成虚拟地址后的基地址指针 */
static struct clk   *adc_clock;         /* 时钟 */

/* ADC转换完成后中断将调用的函数*/
static irqreturn_t adcdone_int_handler(int irq, void *dev_id)  
{  
    wake_up(&s3c2440adc_dev.wait);  /* 唤醒等待队列 */
    return IRQ_HANDLED;
}  

/* ADC驱动的写函数 */  
static ssize_t s3c2440adc_write(struct file *file, const char *buffer, size_t count, loff_t * ppos)  
{  
    unsigned long data;  
  
    if(count!=sizeof(data)){  
    //错误的输入数据大小
	    DPRINTK("the size of input data must be %d\n", sizeof(data));  
        return 0;  
    }  
  
    copy_from_user(&data, buffer, count);  
    s3c2440adc_dev.channel=ADC_WRITE_GETCH(data);       /* 得到需进行AD转换的通道号 */  
    s3c2440adc_dev.prescale=ADC_WRITE_GETPRE(data);     /* 得到预分频系数 */  
  
    DPRINTK("set adc channel=%d, prescale=0x%x\n", s3c2440adc_dev.channel, s3c2440adc_dev.prescale);  
  
    return count;  
}  

/* ADC驱动的读函数 */  
static ssize_t s3c2440adc_read(struct file *filp, char *buffer, size_t count, loff_t *ppos)  
{  
    unsigned long result = 0;  
    unsigned int data;
    if (down_interruptible(&s3c2440adc_dev.lock))  
        return -ERESTARTSYS;  
  
    /* 启动AD转换 */
    iowrite32(START_ADC(s3c2440adc_dev.channel, s3c2440adc_dev.prescale), base_addr + S3C2410_ADCCON); 
    interruptible_sleep_on(&s3c2440adc_dev.wait);               /* 等待AD完成中断*/  
  
    data = ioread32(base_addr + S3C2410_ADCDAT0) & 0x3ff;       /* 保留转换数据寄存器的低10位 */ 
    result = ioread32(base_addr + S3C2410_ADCCON); 
    DPRINTK("AIN[%d] = 0x%x, 0x%x\n", s3c2440adc_dev.channel, data, (unsigned int)result);
  
    copy_to_user(buffer, &data, sizeof(data));      /* 复制到用户空间 */  
  
    up(&s3c2440adc_dev.lock);  
  
    return sizeof(result);  
}  
  
/*文件打开函数*/  
static int s3c2440adc_open(struct inode *inode, struct file *filp)  
{  
    init_MUTEX(&s3c2440adc_dev.lock);  
    init_waitqueue_head(&(s3c2440adc_dev.wait));  
    filp->private_data = s3c2440adc_devp;  /*将设备结构体指针赋值给文件私有数据指针*/
    s3c2440adc_dev.channel=0;  
    s3c2440adc_dev.prescale=0xff;  

    base_addr = ioremap(ADC_CTL_BASE, 0x14);

 	adc_clock = clk_get(NULL, "adc");
	if (!adc_clock) {
		DPRINTK("failed to get adc clock source\n");
		return -ENOENT;
	}
	clk_enable(adc_clock); 

    DPRINTK( "adc opened\n");  
    return 0;  
}  
  
static int s3c2440adc_release(struct inode *inode, struct file *filp)  
{  
    DPRINTK( "adc closed\n");  
    return 0;  
}  
  
static struct file_operations s3c2440adc_fops = {  
    owner:  THIS_MODULE,  
    open:   s3c2440adc_open,  
    read:   s3c2440adc_read,     
    write:  s3c2440adc_write,  
    release:    s3c2440adc_release,  
};  
  
/*初始化并注册cdev*/
static void s3c2440adc_setup_cdev(struct s3c2440adc_dev *dev, int index)
{
    int err, devno = MKDEV(s3c2440adc_major, index);
    cdev_init(&dev->cdev, &s3c2440adc_fops);
    dev->cdev.owner = THIS_MODULE;
    dev->cdev.ops = &s3c2440adc_fops;
    err = cdev_add(&dev->cdev, devno, 1);
    if (err)
        DPRINTK("Error %d adding devno%d", err, index);
}

int __init s3c2440adc_init(void)  
{  
    int result;

    dev_t devno = MKDEV(s3c2440adc_major, 0);

    /* 申请中断 */
    result = request_irq(IRQ_ADC, adcdone_int_handler, SA_INTERRUPT, DEVICE_NAME, NULL);  

    /* 中断号被占用 */
    if (result) {  
        DPRINTK("IRQ%d already in use\n", IRQ_ADC);
  	    return result;  
    }  

    /* 申请设备号*/
    if (s3c2440adc_major)
        result = register_chrdev_region(devno, 1, "s3c2440adc");
    else  /* 动态申请设备号 */
    {
        result = alloc_chrdev_region(&devno, 0, 1, "s3c2440adc");
        s3c2440adc_major = MAJOR(devno);
    }  
    if (result < 0)
        return result;
    
    /* 动态申请设备结构体的内存*/
    s3c2440adc_devp = kmalloc(sizeof(struct s3c2440adc_dev), GFP_KERNEL);
    if (!s3c2440adc_devp)    /*申请失败*/
    {
        result = -ENOMEM;
        goto fail_malloc;
    }
    memset(s3c2440adc_devp, 0, sizeof(struct s3c2440adc_dev));
  
    s3c2440adc_setup_cdev(s3c2440adc_devp, 0);
    return 0;

    fail_malloc: unregister_chrdev_region(devno, 1);
    return result;
}

void __exit s3c2440adc_exit(void)  
{
	if (adc_clock) {
		clk_disable(adc_clock);
		//clk_unuse(adc_clock);
		clk_put(adc_clock);
		adc_clock = NULL;
	}

    cdev_del(&s3c2440adc_devp->cdev);		/*注销cdev*/
    kfree(s3c2440adc_devp);     			/*释放设备结构体内存*/
    unregister_chrdev_region(MKDEV(s3c2440adc_major, 0), 1); /*释放设备号*/
    iounmap(base_addr);                   /* 释放申请的虚拟地址 */
    free_irq(IRQ_ADC, NULL);  			/*释放中断*/
}  

MODULE_AUTHOR("lxm<[e-mail]>");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION(VERSION_STRING); 

module_init(s3c2440adc_init);
module_exit(s3c2440adc_exit);