forked from Minki/linux
1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
201 lines
5.6 KiB
C
201 lines
5.6 KiB
C
/*
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* linux/arch/mips/dec/time.c
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*
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* Copyright (C) 1991, 1992, 1995 Linus Torvalds
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* Copyright (C) 2000, 2003 Maciej W. Rozycki
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*
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* This file contains the time handling details for PC-style clocks as
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* found in some MIPS systems.
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*
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*/
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#include <linux/bcd.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/kernel.h>
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#include <linux/mc146818rtc.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/param.h>
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#include <linux/sched.h>
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#include <linux/string.h>
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#include <linux/time.h>
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#include <linux/types.h>
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#include <asm/bootinfo.h>
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#include <asm/cpu.h>
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#include <asm/div64.h>
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#include <asm/io.h>
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#include <asm/irq.h>
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#include <asm/mipsregs.h>
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#include <asm/sections.h>
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#include <asm/time.h>
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#include <asm/dec/interrupts.h>
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#include <asm/dec/ioasic.h>
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#include <asm/dec/ioasic_addrs.h>
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#include <asm/dec/machtype.h>
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static unsigned long dec_rtc_get_time(void)
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{
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unsigned int year, mon, day, hour, min, sec, real_year;
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int i;
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/* The Linux interpretation of the DS1287 clock register contents:
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* When the Update-In-Progress (UIP) flag goes from 1 to 0, the
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* RTC registers show the second which has precisely just started.
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* Let's hope other operating systems interpret the RTC the same way.
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*/
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/* read RTC exactly on falling edge of update flag */
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for (i = 0; i < 1000000; i++) /* may take up to 1 second... */
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if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)
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break;
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for (i = 0; i < 1000000; i++) /* must try at least 2.228 ms */
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if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
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break;
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/* Isn't this overkill? UIP above should guarantee consistency */
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do {
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sec = CMOS_READ(RTC_SECONDS);
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min = CMOS_READ(RTC_MINUTES);
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hour = CMOS_READ(RTC_HOURS);
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day = CMOS_READ(RTC_DAY_OF_MONTH);
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mon = CMOS_READ(RTC_MONTH);
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year = CMOS_READ(RTC_YEAR);
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} while (sec != CMOS_READ(RTC_SECONDS));
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if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
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sec = BCD2BIN(sec);
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min = BCD2BIN(min);
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hour = BCD2BIN(hour);
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day = BCD2BIN(day);
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mon = BCD2BIN(mon);
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year = BCD2BIN(year);
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}
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/*
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* The PROM will reset the year to either '72 or '73.
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* Therefore we store the real year separately, in one
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* of unused BBU RAM locations.
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*/
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real_year = CMOS_READ(RTC_DEC_YEAR);
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year += real_year - 72 + 2000;
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return mktime(year, mon, day, hour, min, sec);
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}
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/*
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* In order to set the CMOS clock precisely, dec_rtc_set_mmss has to
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* be called 500 ms after the second nowtime has started, because when
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* nowtime is written into the registers of the CMOS clock, it will
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* jump to the next second precisely 500 ms later. Check the Dallas
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* DS1287 data sheet for details.
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*/
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static int dec_rtc_set_mmss(unsigned long nowtime)
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{
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int retval = 0;
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int real_seconds, real_minutes, cmos_minutes;
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unsigned char save_control, save_freq_select;
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/* tell the clock it's being set */
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save_control = CMOS_READ(RTC_CONTROL);
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CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL);
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/* stop and reset prescaler */
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save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
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CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT);
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cmos_minutes = CMOS_READ(RTC_MINUTES);
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if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
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cmos_minutes = BCD2BIN(cmos_minutes);
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/*
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* since we're only adjusting minutes and seconds,
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* don't interfere with hour overflow. This avoids
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* messing with unknown time zones but requires your
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* RTC not to be off by more than 15 minutes
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*/
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real_seconds = nowtime % 60;
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real_minutes = nowtime / 60;
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if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
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real_minutes += 30; /* correct for half hour time zone */
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real_minutes %= 60;
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if (abs(real_minutes - cmos_minutes) < 30) {
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if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
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real_seconds = BIN2BCD(real_seconds);
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real_minutes = BIN2BCD(real_minutes);
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}
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CMOS_WRITE(real_seconds, RTC_SECONDS);
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CMOS_WRITE(real_minutes, RTC_MINUTES);
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} else {
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printk(KERN_WARNING
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"set_rtc_mmss: can't update from %d to %d\n",
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cmos_minutes, real_minutes);
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retval = -1;
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}
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/* The following flags have to be released exactly in this order,
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* otherwise the DS1287 will not reset the oscillator and will not
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* update precisely 500 ms later. You won't find this mentioned
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* in the Dallas Semiconductor data sheets, but who believes data
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* sheets anyway ... -- Markus Kuhn
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*/
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CMOS_WRITE(save_control, RTC_CONTROL);
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CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
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return retval;
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}
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static int dec_timer_state(void)
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{
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return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
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}
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static void dec_timer_ack(void)
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{
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CMOS_READ(RTC_REG_C); /* Ack the RTC interrupt. */
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}
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static unsigned int dec_ioasic_hpt_read(void)
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{
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/*
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* The free-running counter is 32-bit which is good for about
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* 2 minutes, 50 seconds at possible count rates of up to 25MHz.
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*/
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return ioasic_read(IO_REG_FCTR);
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}
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static void dec_ioasic_hpt_init(unsigned int count)
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{
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ioasic_write(IO_REG_FCTR, ioasic_read(IO_REG_FCTR) - count);
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}
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void __init dec_time_init(void)
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{
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rtc_get_time = dec_rtc_get_time;
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rtc_set_mmss = dec_rtc_set_mmss;
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mips_timer_state = dec_timer_state;
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mips_timer_ack = dec_timer_ack;
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if (!cpu_has_counter && IOASIC) {
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/* For pre-R4k systems we use the I/O ASIC's counter. */
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mips_hpt_read = dec_ioasic_hpt_read;
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mips_hpt_init = dec_ioasic_hpt_init;
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}
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/* Set up the rate of periodic DS1287 interrupts. */
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CMOS_WRITE(RTC_REF_CLCK_32KHZ | (16 - LOG_2_HZ), RTC_REG_A);
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}
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EXPORT_SYMBOL(do_settimeofday);
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void __init dec_timer_setup(struct irqaction *irq)
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{
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setup_irq(dec_interrupt[DEC_IRQ_RTC], irq);
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/* Enable periodic DS1287 interrupts. */
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CMOS_WRITE(CMOS_READ(RTC_REG_B) | RTC_PIE, RTC_REG_B);
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}
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