adc.c

AT9260处理器Linux2.6.24内核AD转换驱动程序

//#include <linux/config.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/ioport.h>
#include <linux/crc32.h>
#include <linux/device.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/miscdevice.h>
#include <linux/list.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <asm/hardware.h>
#include <asm/system.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <asm/uaccess.h>
#include <linux/spinlock.h>
#include <linux/irq.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/arch/gpio.h>
#include <asm/arch/at91_adc.h>
#include <linux/clk.h>

#include "adc.h"

#define	MAX_CHAN_NUM	4
#define MAX_SAMPLES	128000
#define	ADC_GET		1		

typedef struct adc_data {
	unsigned int data[MAX_CHAN_NUM];
}adc_data;

void __iomem *adc_base;
struct clk *adc_clk;
unsigned char *adc_val;

static inline int at91_adc_drdy(unsigned int chan);
static inline unsigned char channel_read(unsigned int chan);

/* Function to read last conversion of channels*/
static inline unsigned char channel_read(unsigned int chan)
{   
	__raw_writel(0x02, adc_base + ADC_CR); //Start the ADC
	while(!at91_adc_drdy(chan)) //Is conversion ready?
		cpu_relax();
	return __raw_readl(adc_base + ADC_CDR + chan*4); //Read & Return the conversion
}

/* Function to check if DRDY is set */
static inline int at91_adc_drdy(unsigned int chan)
{
	return (__raw_readl(adc_base + ADC_SR) & (0x01<<chan));
}


static int adc_ioctl(struct inode *inode, struct file *file,
                     unsigned int cmd, unsigned long arg)
{
	static struct adc_data local_data;
	int i=0;

	if (copy_from_user(&local_data, (struct adc_data *)arg, sizeof(local_data)))
		return -EFAULT;

	switch (cmd) {
		case ADC_GET:
			for(i = 0; i < MAX_CHAN_NUM; i ++) local_data.data[i] = channel_read(i);
			if (copy_to_user((struct adc_data *)arg, &local_data, sizeof(local_data)))
				return -EFAULT;

			return 0;
		break;
		default:
			return -EINVAL;
		break;
	}     	
	
  return -EINVAL;

}

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

	return 0;
}

static int adc_release(struct inode *inode, struct file *file)
{

	return 0;
}


static struct file_operations adc_fops = {
	.open	= adc_open,
	.release	= adc_release,
	.ioctl  	= adc_ioctl,
};

static struct miscdevice adc_dev = {
	.minor  = 198,
	.name   = "ADC",
	.fops   = &adc_fops,
};

static int __init adc_init(void)
{
	
	/* ADC Set Up */
	adc_clk = clk_get(NULL, "adc_clk"); //Start ADC Clock
	clk_enable(adc_clk);
	at91_set_A_periph(AT91_PIN_PC0,0); //Mux ADC0 to GPIO
	at91_set_A_periph(AT91_PIN_PC1,0); //Mux ADC1 to GPIO
	at91_set_A_periph(AT91_PIN_PC2,0); //Mux ADC2 to GPIO
	at91_set_A_periph(AT91_PIN_PC3,0); //Mux ADC3 to GPIO
	adc_base = ioremap(AT91SAM9260_BASE_ADC,SZ_16K); //Map the mem region
	__raw_writel(0x01, adc_base + ADC_CR); //Reset the ADC
	__raw_writel((SHTIM << 24 | STARTUP << 16 | PRESCAL << 8 | SLEEP_MODE << 5 |
	        LOWRES << 4 | TRGSEL << 1 | TRGEN), adc_base + ADC_MR); //Mode setup
 	__raw_writel(CH_EN, adc_base + ADC_CHER);     //Enable Channels
	__raw_writel(CH_DIS, adc_base + ADC_CHDR);    //Disable Channels

	misc_register(&adc_dev);

	return 0;
}

static void __exit adc_exit(void)
{
	clk_disable(adc_clk); //Turn off ADC clock
	clk_put(adc_clk);
	iounmap(adc_base);    //Unmap the ADC mem region
	misc_deregister(&adc_dev);
}


MODULE_AUTHOR("Yanjun Luo <[e-mail]");
MODULE_DESCRIPTION("adc driver");
MODULE_LICENSE("GPL");

module_init(adc_init);
module_exit(adc_exit);