diff options
Diffstat (limited to 'arch/mips/dec/time.c')
| -rw-r--r-- | arch/mips/dec/time.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/arch/mips/dec/time.c b/arch/mips/dec/time.c new file mode 100644 index 000000000..c38686f89 --- /dev/null +++ b/arch/mips/dec/time.c @@ -0,0 +1,172 @@ +// 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]); +} |