Orange Pi5 kernel

// 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]);
}