rtc.c

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

/*
 * linux/arch/sh/kernel/rtc.c -- SH3 / SH4 on-chip RTC support
 *
 *  Copyright (C) 2000  Philipp Rumpf <[e-mail]>
 *  Copyright (C) 1999  Tetsuya Okada & Niibe Yutaka
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/time.h>

#include <asm/io.h>
#include <asm/rtc.h>

#ifndef BCD_TO_BIN
#define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10)
#endif

#ifndef BIN_TO_BCD
#define BIN_TO_BCD(val) ((val)=(((val)/10)<<4) + (val)%10)
#endif

void sh_rtc_gettimeofday(struct timeval *tv)
{
	unsigned int sec128, sec, min, hr, wk, day, mon, yr, yr100;

 again:
	do {
		ctrl_outb(0, RCR1);  /* Clear CF-bit */
		sec128 = ctrl_inb(R64CNT);
		sec = ctrl_inb(RSECCNT);
		min = ctrl_inb(RMINCNT);
		hr  = ctrl_inb(RHRCNT);
		wk  = ctrl_inb(RWKCNT);
		day = ctrl_inb(RDAYCNT);
		mon = ctrl_inb(RMONCNT);
#if defined(__SH4__)
		yr  = ctrl_inw(RYRCNT);
		yr100 = (yr >> 8);
		yr &= 0xff;
#else
		yr  = ctrl_inb(RYRCNT);
		yr100 = (yr == 0x99) ? 0x19 : 0x20;
#endif
	} while ((ctrl_inb(RCR1) & RCR1_CF) != 0);

#if RTC_BIT_INVERTED != 0
	/* Work around to avoid reading incorrect value. */
	if (sec128 == RTC_BIT_INVERTED) {
		schedule_timeout(1);
		goto again;
	}
#endif

	BCD_TO_BIN(yr100);
	BCD_TO_BIN(yr);
	BCD_TO_BIN(mon);
	BCD_TO_BIN(day);
	BCD_TO_BIN(hr);
	BCD_TO_BIN(min);
	BCD_TO_BIN(sec);

	if (yr > 99 || mon < 1 || mon > 12 || day > 31 || day < 1 ||
	    hr > 23 || min > 59 || sec > 59) {
		printk(KERN_ERR
		       "SH RTC: invalid value, resetting to 1 Jan 2000\n");
		ctrl_outb(RCR2_RESET, RCR2);  /* Reset & Stop */
		ctrl_outb(0, RSECCNT);
		ctrl_outb(0, RMINCNT);
		ctrl_outb(0, RHRCNT);
		ctrl_outb(6, RWKCNT);
		ctrl_outb(1, RDAYCNT);
		ctrl_outb(1, RMONCNT);
#if defined(__SH4__)
		ctrl_outw(0x2000, RYRCNT);
#else
		ctrl_outb(0, RYRCNT);
#endif
		ctrl_outb(RCR2_RTCEN|RCR2_START, RCR2);  /* Start */
		goto again;
	}

#if RTC_BIT_INVERTED != 0
	if ((sec128 & RTC_BIT_INVERTED))
		sec--;
#endif

	tv->tv_sec = mktime(yr100 * 100 + yr, mon, day, hr, min, sec);
	tv->tv_usec = (sec128 * 1000000) / 128;
}

int sh_rtc_settimeofday(const struct timeval *tv)
{
	unsigned long nowtime = tv->tv_sec;
	int retval = 0;
	int real_seconds, real_minutes, cmos_minutes;

	ctrl_outb(RCR2_RESET, RCR2);  /* Reset pre-scaler & stop RTC */

	cmos_minutes = ctrl_inb(RMINCNT);
	BCD_TO_BIN(cmos_minutes);

	/*
	 * since we're only adjusting minutes and seconds,
	 * don't interfere with hour overflow. This avoids
	 * messing with unknown time zones but requires your
	 * RTC not to be off by more than 15 minutes
	 */
	real_seconds = nowtime % 60;
	real_minutes = nowtime / 60;
	if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
		real_minutes += 30;	/* correct for half hour time zone */
	real_minutes %= 60;

	if (abs(real_minutes - cmos_minutes) < 30) {
		BIN_TO_BCD(real_seconds);
		BIN_TO_BCD(real_minutes);
		ctrl_outb(real_seconds, RSECCNT);
		ctrl_outb(real_minutes, RMINCNT);
	} else {
		printk(KERN_WARNING
		       "set_rtc_time: can't update from %d to %d\n",
		       cmos_minutes, real_minutes);
		retval = -1;
	}

	ctrl_outb(RCR2_RTCEN|RCR2_START, RCR2);  /* Start RTC */

	return retval;
}