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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_clock(struct timespec *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 = mktime(year, mon, day, hour, min, sec);
ts->tv_nsec = 0;
}
/*
* In order to set the CMOS clock precisely, rtc_mips_set_mmss 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 rtc_mips_set_mmss(unsigned long nowtime)
{
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_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) {
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]);
}
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