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172 lines
4.8 KiB
172 lines
4.8 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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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_clock64(struct timespec64 *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 = mktime64(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, update_persistent_clock64 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 update_persistent_clock64(struct timespec64 now) |
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{ |
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time64_t nowtime = now.tv_sec; |
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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_minutes = div_s64_rem(nowtime, 60, &real_seconds); |
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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_once(KERN_NOTICE |
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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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int ioasic_clock = 0; |
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u32 start, end; |
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int i = HZ / 8; |
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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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/* On some I/O ASIC systems we have the I/O ASIC's counter. */ |
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if (IOASIC) |
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ioasic_clock = dec_ioasic_clocksource_init() == 0; |
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if (cpu_has_counter) { |
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ds1287_timer_state(); |
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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) * 8; |
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printk(KERN_INFO "MIPS counter frequency %dHz\n", |
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mips_hpt_frequency); |
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/* |
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* All R4k DECstations suffer from the CP0 Count erratum, |
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* so we can't use the timer as a clock source, and a clock |
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* event both at a time. An accurate wall clock is more |
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* important than a high-precision interval timer so only |
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* use the timer as a clock source, and not a clock event |
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* if there's no I/O ASIC counter available to serve as a |
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* clock source. |
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*/ |
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if (!ioasic_clock) { |
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init_r4k_clocksource(); |
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mips_hpt_frequency = 0; |
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} |
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} |
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ds1287_clockevent_init(dec_interrupt[DEC_IRQ_RTC]); |
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}
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