/*
* linux/arch/mips/dec/time.c
*
* 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/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/mc146818rtc.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/param.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/time.h>
#include <linux/types.h>
#include <asm/bootinfo.h>
#include <asm/cpu.h>
#include <asm/div64.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/mipsregs.h>
#include <asm/sections.h>
#include <asm/time.h>
#include <asm/dec/interrupts.h>
#include <asm/dec/ioasic.h>
#include <asm/dec/ioasic_addrs.h>
#include <asm/dec/machtype.h>
/*
* Returns true if a clock update is in progress
*/
static inline unsigned char dec_rtc_is_updating(void)
{
unsigned char uip;
unsigned long flags;
spin_lock_irqsave(&rtc_lock, flags);
uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
spin_unlock_irqrestore(&rtc_lock, flags);
return uip;
}
static unsigned long dec_rtc_get_time(void)
{
unsigned int year, mon, day, hour, min, sec, real_year;
int i;
unsigned long flags;
/* The Linux interpretation of the DS1287 clock register contents:
* When the Update-In-Progress (UIP) flag goes from 1 to 0, the
* RTC registers show the second which has precisely just started.
* Let's hope other operating systems interpret the RTC the same way.
*/
/* read RTC exactly on falling edge of update flag */
for (i = 0; i < 1000000; i++) /* may take up to 1 second... */
if (dec_rtc_is_updating())
break;
for (i = 0; i < 1000000; i++) /* must try at least 2.228 ms */
if (!dec_rtc_is_updating())
break;
spin_lock_irqsave(&rtc_lock, flags);
/* Isn't this overkill? UIP above should guarantee consistency */
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);
} while (sec != CMOS_READ(RTC_SECONDS));
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);
}
/*
* 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);
spin_unlock_irqrestore(&rtc_lock, flags);
year += real_year - 72 + 2000;
return mktime(year, mon, day, hour, min, sec);
}
/*
* In order to set the CMOS clock precisely, dec_rtc_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.
*/
static int dec_rtc_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(KERN_WARNING
"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;
}
static int dec_timer_state(void)
{
return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
}
static void dec_timer_ack(void)
{
CMOS_READ(RTC_REG_C); /* Ack the RTC interrupt. */
}
static unsigned int dec_ioasic_hpt_read(void)
{
/*
* The free-running counter is 32-bit which is good for about
* 2 minutes, 50 seconds at possible count rates of up to 25MHz.
*/
return ioasic_read(IO_REG_FCTR);
}
static void dec_ioasic_hpt_init(unsigned int count)
{
ioasic_write(IO_REG_FCTR, ioasic_read(IO_REG_FCTR) - count);
}
void __init dec_time_init(void)
{
rtc_get_time = dec_rtc_get_time;
rtc_set_mmss = dec_rtc_set_mmss;
mips_timer_state = dec_timer_state;
mips_timer_ack = dec_timer_ack;
if (!cpu_has_counter && IOASIC) {
/* For pre-R4k systems we use the I/O ASIC's counter. */
mips_hpt_read = dec_ioasic_hpt_read;
mips_hpt_init = dec_ioasic_hpt_init;
}
/* Set up the rate of periodic DS1287 interrupts. */
CMOS_WRITE(RTC_REF_CLCK_32KHZ | (16 - LOG_2_HZ), RTC_REG_A);
}
EXPORT_SYMBOL(do_settimeofday);
void __init dec_timer_setup(struct irqaction *irq)
{
setup_irq(dec_interrupt[DEC_IRQ_RTC], irq);
/* Enable periodic DS1287 interrupts. */
CMOS_WRITE(CMOS_READ(RTC_REG_B) | RTC_PIE, RTC_REG_B);
}
