155 lines
4.2 KiB
C
155 lines
4.2 KiB
C
/*
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* Copyright (C) 1991, 1992, 1995 Linus Torvalds
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* Copyright (C) 2000, 2003 Maciej W. Rozycki
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*
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* This file contains the time handling details for PC-style clocks as
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* found in some MIPS systems.
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*
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*/
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#include <linux/bcd.h>
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#include <linux/init.h>
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#include <linux/mc146818rtc.h>
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#include <linux/param.h>
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#include <asm/cpu-features.h>
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#include <asm/ds1287.h>
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#include <asm/time.h>
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#include <asm/dec/interrupts.h>
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#include <asm/dec/ioasic.h>
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#include <asm/dec/machtype.h>
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void read_persistent_clock(struct timespec *ts)
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{
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unsigned int year, mon, day, hour, min, sec, real_year;
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unsigned long flags;
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spin_lock_irqsave(&rtc_lock, flags);
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do {
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sec = CMOS_READ(RTC_SECONDS);
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min = CMOS_READ(RTC_MINUTES);
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hour = CMOS_READ(RTC_HOURS);
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day = CMOS_READ(RTC_DAY_OF_MONTH);
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mon = CMOS_READ(RTC_MONTH);
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year = CMOS_READ(RTC_YEAR);
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/*
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* The PROM will reset the year to either '72 or '73.
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* Therefore we store the real year separately, in one
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* of unused BBU RAM locations.
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*/
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real_year = CMOS_READ(RTC_DEC_YEAR);
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} while (sec != CMOS_READ(RTC_SECONDS));
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spin_unlock_irqrestore(&rtc_lock, flags);
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if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
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sec = bcd2bin(sec);
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min = bcd2bin(min);
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hour = bcd2bin(hour);
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day = bcd2bin(day);
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mon = bcd2bin(mon);
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year = bcd2bin(year);
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}
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year += real_year - 72 + 2000;
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ts->tv_sec = mktime(year, mon, day, hour, min, sec);
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ts->tv_nsec = 0;
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}
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/*
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* In order to set the CMOS clock precisely, rtc_mips_set_mmss has to
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* be called 500 ms after the second nowtime has started, because when
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* nowtime is written into the registers of the CMOS clock, it will
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* jump to the next second precisely 500 ms later. Check the Dallas
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* DS1287 data sheet for details.
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*/
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int rtc_mips_set_mmss(unsigned long nowtime)
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{
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int retval = 0;
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int real_seconds, real_minutes, cmos_minutes;
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unsigned char save_control, save_freq_select;
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/* irq are locally disabled here */
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spin_lock(&rtc_lock);
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/* tell the clock it's being set */
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save_control = CMOS_READ(RTC_CONTROL);
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CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL);
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/* stop and reset prescaler */
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save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
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CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT);
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cmos_minutes = CMOS_READ(RTC_MINUTES);
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if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
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cmos_minutes = bcd2bin(cmos_minutes);
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/*
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* since we're only adjusting minutes and seconds,
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* don't interfere with hour overflow. This avoids
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* messing with unknown time zones but requires your
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* RTC not to be off by more than 15 minutes
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*/
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real_seconds = nowtime % 60;
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real_minutes = nowtime / 60;
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if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
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real_minutes += 30; /* correct for half hour time zone */
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real_minutes %= 60;
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if (abs(real_minutes - cmos_minutes) < 30) {
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if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
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real_seconds = bin2bcd(real_seconds);
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real_minutes = bin2bcd(real_minutes);
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}
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CMOS_WRITE(real_seconds, RTC_SECONDS);
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CMOS_WRITE(real_minutes, RTC_MINUTES);
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} else {
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printk(KERN_WARNING
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"set_rtc_mmss: can't update from %d to %d\n",
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cmos_minutes, real_minutes);
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retval = -1;
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}
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/* The following flags have to be released exactly in this order,
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* otherwise the DS1287 will not reset the oscillator and will not
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* update precisely 500 ms later. You won't find this mentioned
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* in the Dallas Semiconductor data sheets, but who believes data
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* sheets anyway ... -- Markus Kuhn
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*/
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CMOS_WRITE(save_control, RTC_CONTROL);
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CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
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spin_unlock(&rtc_lock);
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return retval;
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}
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void __init plat_time_init(void)
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{
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u32 start, end;
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int i = HZ / 10;
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/* Set up the rate of periodic DS1287 interrupts. */
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ds1287_set_base_clock(HZ);
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if (cpu_has_counter) {
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while (!ds1287_timer_state())
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;
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start = read_c0_count();
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while (i--)
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while (!ds1287_timer_state())
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;
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end = read_c0_count();
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mips_hpt_frequency = (end - start) * 10;
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printk(KERN_INFO "MIPS counter frequency %dHz\n",
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mips_hpt_frequency);
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} else if (IOASIC)
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/* For pre-R4k systems we use the I/O ASIC's counter. */
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dec_ioasic_clocksource_init();
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ds1287_clockevent_init(dec_interrupt[DEC_IRQ_RTC]);
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}
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