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-rw-r--r--arch/mips/dec/time.c172
1 files changed, 172 insertions, 0 deletions
diff --git a/arch/mips/dec/time.c b/arch/mips/dec/time.c
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+++ b/arch/mips/dec/time.c
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+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 1991, 1992, 1995 Linus Torvalds
+ * Copyright (C) 2000, 2003 Maciej W. Rozycki
+ *
+ * This file contains the time handling details for PC-style clocks as
+ * found in some MIPS systems.
+ *
+ */
+#include <linux/bcd.h>
+#include <linux/init.h>
+#include <linux/mc146818rtc.h>
+#include <linux/param.h>
+
+#include <asm/cpu-features.h>
+#include <asm/ds1287.h>
+#include <asm/time.h>
+#include <asm/dec/interrupts.h>
+#include <asm/dec/ioasic.h>
+#include <asm/dec/machtype.h>
+
+void read_persistent_clock64(struct timespec64 *ts)
+{
+ unsigned int year, mon, day, hour, min, sec, real_year;
+ unsigned long flags;
+
+ spin_lock_irqsave(&rtc_lock, flags);
+
+ do {
+ sec = CMOS_READ(RTC_SECONDS);
+ min = CMOS_READ(RTC_MINUTES);
+ hour = CMOS_READ(RTC_HOURS);
+ day = CMOS_READ(RTC_DAY_OF_MONTH);
+ mon = CMOS_READ(RTC_MONTH);
+ year = CMOS_READ(RTC_YEAR);
+ /*
+ * The PROM will reset the year to either '72 or '73.
+ * Therefore we store the real year separately, in one
+ * of unused BBU RAM locations.
+ */
+ real_year = CMOS_READ(RTC_DEC_YEAR);
+ } while (sec != CMOS_READ(RTC_SECONDS));
+
+ spin_unlock_irqrestore(&rtc_lock, flags);
+
+ if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+ sec = bcd2bin(sec);
+ min = bcd2bin(min);
+ hour = bcd2bin(hour);
+ day = bcd2bin(day);
+ mon = bcd2bin(mon);
+ year = bcd2bin(year);
+ }
+
+ year += real_year - 72 + 2000;
+
+ ts->tv_sec = mktime64(year, mon, day, hour, min, sec);
+ ts->tv_nsec = 0;
+}
+
+/*
+ * In order to set the CMOS clock precisely, update_persistent_clock64 has to
+ * be called 500 ms after the second nowtime has started, because when
+ * nowtime is written into the registers of the CMOS clock, it will
+ * jump to the next second precisely 500 ms later. Check the Dallas
+ * DS1287 data sheet for details.
+ */
+int update_persistent_clock64(struct timespec64 now)
+{
+ time64_t nowtime = now.tv_sec;
+ int retval = 0;
+ int real_seconds, real_minutes, cmos_minutes;
+ unsigned char save_control, save_freq_select;
+
+ /* irq are locally disabled here */
+ spin_lock(&rtc_lock);
+ /* tell the clock it's being set */
+ save_control = CMOS_READ(RTC_CONTROL);
+ CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL);
+
+ /* stop and reset prescaler */
+ save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
+ CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT);
+
+ cmos_minutes = CMOS_READ(RTC_MINUTES);
+ if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
+ cmos_minutes = bcd2bin(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_minutes = div_s64_rem(nowtime, 60, &real_seconds);
+ 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) {
+ if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+ real_seconds = bin2bcd(real_seconds);
+ real_minutes = bin2bcd(real_minutes);
+ }
+ CMOS_WRITE(real_seconds, RTC_SECONDS);
+ CMOS_WRITE(real_minutes, RTC_MINUTES);
+ } else {
+ printk_once(KERN_NOTICE
+ "set_rtc_mmss: can't update from %d to %d\n",
+ cmos_minutes, real_minutes);
+ retval = -1;
+ }
+
+ /* The following flags have to be released exactly in this order,
+ * otherwise the DS1287 will not reset the oscillator and will not
+ * update precisely 500 ms later. You won't find this mentioned
+ * in the Dallas Semiconductor data sheets, but who believes data
+ * sheets anyway ... -- Markus Kuhn
+ */
+ CMOS_WRITE(save_control, RTC_CONTROL);
+ CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
+ spin_unlock(&rtc_lock);
+
+ return retval;
+}
+
+void __init plat_time_init(void)
+{
+ int ioasic_clock = 0;
+ u32 start, end;
+ int i = HZ / 8;
+
+ /* Set up the rate of periodic DS1287 interrupts. */
+ ds1287_set_base_clock(HZ);
+
+ /* On some I/O ASIC systems we have the I/O ASIC's counter. */
+ if (IOASIC)
+ ioasic_clock = dec_ioasic_clocksource_init() == 0;
+ if (cpu_has_counter) {
+ ds1287_timer_state();
+ while (!ds1287_timer_state())
+ ;
+
+ start = read_c0_count();
+
+ while (i--)
+ while (!ds1287_timer_state())
+ ;
+
+ end = read_c0_count();
+
+ mips_hpt_frequency = (end - start) * 8;
+ printk(KERN_INFO "MIPS counter frequency %dHz\n",
+ mips_hpt_frequency);
+
+ /*
+ * All R4k DECstations suffer from the CP0 Count erratum,
+ * so we can't use the timer as a clock source, and a clock
+ * event both at a time. An accurate wall clock is more
+ * important than a high-precision interval timer so only
+ * use the timer as a clock source, and not a clock event
+ * if there's no I/O ASIC counter available to serve as a
+ * clock source.
+ */
+ if (!ioasic_clock) {
+ init_r4k_clocksource();
+ mips_hpt_frequency = 0;
+ }
+ }
+
+ ds1287_clockevent_init(dec_interrupt[DEC_IRQ_RTC]);
+}