/*
 * h8-adc.c
*/

#if !defined(__KERNEL__)
#define	__KERNEL__
#endif

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/delay.h>
#include <linux/wait.h>
#include <linux/poll.h>
#include <asm/regs306x.h>
#include <asm/delay.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/ioctl.h>

typedef union {
	unsigned short WORD;
	struct {
		unsigned char H:8;
		unsigned char L:8;
	} BYTE;
} _ADDR;


#define ADC_DEVNAME	"h8_adc"
#define ADC_MAJOR	191
#define ADC_IRQ	23


MODULE_AUTHOR( "sushi-k@quake3.jp" );
MODULE_DESCRIPTION( "H8/3069F ADC driver." );
MODULE_LICENSE( "GPL" );

static unsigned int adc_major = ADC_MAJOR;
static char *adc_devname = ADC_DEVNAME;
static unsigned char *msg = "h8_adc.o";

static unsigned int adc_ch = 0;
static int f_adc = 0;
static _ADDR	ad_data;

// アクセス数
static int f_access = 0;

// 読み出しポインタ
static int read_p = 0;


// 割り込み処理

void adc_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	volatile unsigned char *addr;
	volatile unsigned char *adcsr = (volatile unsigned char *)ADCSR;
	unsigned char d;
	
	// いちど空読み
	d = *adcsr;
	// ADF & ADIE & ADST クリア
	*adcsr &= 0x1F;
	addr = (volatile unsigned char *)ADDRAH + (adc_ch * 2);
	
	// データ読みだし、上位、下位の順で読み取る
	ad_data.BYTE.H = *addr;
	addr++;
	ad_data.BYTE.L = *addr;
	// 6ビットシフト
	ad_data.WORD = ad_data.WORD >> 6;
	// 終了フラグセット
	f_adc = 1;
}



static int adc_open(struct inode *inode, struct file *filp)
{
	// 1プロセスしかオープンできないようにする
	if( f_access ) {
		printk( "%s: ADC is already used.", msg );
		return -EFAULT;
	}
	
	adc_ch = MINOR(inode->i_rdev);
	if( adc_ch > 3 ) {
		printk( "%s: ch > 3 is not supported.", msg );
		return -EFAULT;
	}
	
	read_p = 0;
	f_access++;
	MOD_INC_USE_COUNT;
	return 0;
}

// release

static int adc_release(struct inode *inode, struct file *filp)
{
	f_access--;
	
	MOD_DEC_USE_COUNT;
	return 0;
}


static ssize_t
adc_read(struct file *filp, char *buf, size_t count, loff_t *f_pos)
{
	volatile unsigned char *adcsr = (volatile unsigned char *)ADCSR;
	
	if( read_p == 0 ) {
		// 単一モードADCスタート
		f_adc = 0;
		*adcsr = 0x60 | adc_ch;
		// 割り込み待ち
		while( ! f_adc )
			schedule();
	}
	
	if( count >= 2 ) {
		buf[0] = ad_data.BYTE.H;
		buf[1] = ad_data.BYTE.L;
		read_p = 2;
	}
	else if( count != 0 ) {
		if( read_p == 0 ) {
			buf[0] = ad_data.BYTE.H;
			read_p++;
		}
		else {
			buf[0] = ad_data.BYTE.L;
			read_p++;
		}
	}
	if( read_p > 1 ){
		read_p = 0;
	}
	
	return read_p;
}


struct file_operations adc_fops = {
	owner:   THIS_MODULE,
	read:    adc_read,
	write:   NULL,
	open:    adc_open,
	release: adc_release,
	ioctl:   NULL,
};


// init

static int __init
adc_init(void)
{
	int retval;
	
	// デバイスドライバ登録
	retval = register_chrdev(adc_major, adc_devname , &adc_fops);
	if (retval < 0) {
    	printk(KERN_ERR "Cannnot register: %s(%d)\n", adc_devname, adc_major);
    	return retval;
	}
	else {
    	printk(KERN_INFO "%s(%d): registered.\n", adc_devname, adc_major );
  	}
	
	retval = request_irq(ADC_IRQ, adc_interrupt, SA_INTERRUPT, adc_devname, NULL);
	if( retval < 0 ) {
		printk(KERN_ERR "%s(%d): Cannot get irq %d.\n", adc_devname, adc_major,ADC_IRQ );
		return retval;
	}
	f_access = 0;
	adc_ch = 0;
	read_p = 0;
	
  	return 0;
}

// exit

static void __exit
adc_cleanup(void)
{
	// 割り込み解放
	free_irq( ADC_IRQ, NULL );
  	printk( KERN_INFO "%s : removed.\n", msg );
}

// モジュールの初期化、クリーンアップ関数登録
module_init(adc_init);
module_exit(adc_cleanup);