rtc.c

微内核软实时操作系统

/*-
 * Copyright (c) 2005, Kohsuke Ohtani
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the author nor the names of any co-contributors 
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * rtc.c - Real time clock driver
 */
#include <driver.h>
#include <io.h>

/* Cmos */
#define CMOS_INDEX	0x70
#define CMOS_DATA	0x71

/* CMOS address */
#define CMOS_SEC	0x00
#define CMOS_MIN	0x02
#define CMOS_HOUR	0x04
#define CMOS_DAY	0x07
#define CMOS_MON	0x08
#define CMOS_YEAR	0x09
#define CMOS_STS_A	0x0a
#define CMOS_UIP	  0x80
#define CMOS_STS_B	0x0b
#define CMOS_BCD	  0x04


#define DAYSPERYEAR	(31+28+31+30+31+30+31+31+30+31+30+31)

static int rtc_read();
static int rtc_init();

/*
 * Driver structure
 */
struct driver rtc_drv __driver_entry = {
	/* name */	"Realtime Clock",
	/* order */	4,
	/* init */	rtc_init,
};

static struct devio rtc_io = {
	/* open */	NULL,
	/* close */	NULL,
	/* read */	rtc_read,
	/* write */	NULL,
	/* ioctl */	NULL,
	/* event */	NULL,
};

static const int daysinmonth[] =
    { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
static device_t rtc_dev;	/* Device object */


static u_int cmos_read(int index)
{
	u_int value;

	irq_lock();
	outb(index, CMOS_INDEX);
	value = inb(CMOS_DATA);
	irq_unlock();
	return value;
}

/*
static void cmos_write(int index, int value)
{
    irq_lock();
    outb(index, CMOS_INDEX);
    outb(value, CMOS_DATA);
    irq_unlock();
}
*/

static int bcd2bin(int bcd)
{
	return (bcd & 0x0f) + ((bcd >> 4) & 0xf) * 10;
}

/*
static int bin2bcd(int bin)
{
    return ((bin / 10) << 4) + (bin % 10);
}
*/

static int is_leap(int year)
{
	if ((year % 4 == 0) && (year % 100 != 0))
		return 1;
	if (year % 400 == 0)
		return 1;
	return 0;
}

/*
 * Return current seconds (seconds since Epoch)
 */
static u_long cmos_gettime(void)
{
	unsigned int sec, min, hour, day, mon, year;
	int i;
	unsigned int days;

	/* Wait until data ready */
	for (i = 0; i < 1000000; i++)
		if (!(cmos_read(CMOS_STS_A) & CMOS_UIP))
			break;

	sec = cmos_read(CMOS_SEC);
	min = cmos_read(CMOS_MIN);
	hour = cmos_read(CMOS_HOUR);
	day = cmos_read(CMOS_DAY);
	mon = cmos_read(CMOS_MON);
	year = cmos_read(CMOS_YEAR);

	if (!(cmos_read(CMOS_STS_B) & CMOS_BCD)) {
		sec = bcd2bin(sec);
		min = bcd2bin(min);
		hour = bcd2bin(hour);
		day = bcd2bin(day);
		mon = bcd2bin(mon);
		year = bcd2bin(year);
	}
	if (year < 80)
		year += 2000;
	else
		year += 1900;

	/*	printk("clock_gettime: %d/%d/%d %d:%d:%d\n",
		year, mon, day, hour, min, sec); */

	days = 0;
	for (i = 1970; i < year; i++)
		days += DAYSPERYEAR + is_leap(i);
	for (i = 1; i < mon; i++)
		days += daysinmonth[i - 1];
	if ((mon > 2) && is_leap(year))
		days++;
	days += day - 1;

	sec = (((days * 24 + hour) * 60) + min) * 60 + sec;
	return sec;
}

static int rtc_read(device_t dev, char *buf, size_t *nbyte, int blkno)
{
	if (*nbyte < sizeof(u_long))
		return 0;
	*(u_long *)buf = cmos_gettime();
	*nbyte = sizeof(u_long);
	return 0;
}

/*
 * Initialize
 */
static int rtc_init(void)
{
	/* Create device object */
	rtc_dev = device_create(&rtc_io, "rtc");
	ASSERT(rtc_dev);

	return 0;
}