181 lines
4.8 KiB
C
181 lines
4.8 KiB
C
/*
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* arch/ppc64/kernel/maple_time.c
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*
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* (c) Copyright 2004 Benjamin Herrenschmidt (benh@kernel.crashing.org),
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* IBM Corp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#undef DEBUG
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#include <linux/config.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/param.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/init.h>
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#include <linux/time.h>
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#include <linux/adb.h>
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#include <linux/pmu.h>
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#include <linux/interrupt.h>
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#include <linux/mc146818rtc.h>
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#include <linux/bcd.h>
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#include <asm/sections.h>
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#include <asm/prom.h>
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#include <asm/system.h>
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#include <asm/io.h>
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#include <asm/pgtable.h>
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#include <asm/machdep.h>
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#include <asm/time.h>
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#include "maple.h"
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#ifdef DEBUG
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#define DBG(x...) printk(x)
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#else
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#define DBG(x...)
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#endif
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extern void GregorianDay(struct rtc_time * tm);
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static int maple_rtc_addr;
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static int maple_clock_read(int addr)
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{
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outb_p(addr, maple_rtc_addr);
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return inb_p(maple_rtc_addr+1);
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}
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static void maple_clock_write(unsigned long val, int addr)
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{
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outb_p(addr, maple_rtc_addr);
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outb_p(val, maple_rtc_addr+1);
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}
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void maple_get_rtc_time(struct rtc_time *tm)
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{
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int uip, i;
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/* The Linux interpretation of the CMOS 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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/* Since the UIP flag is set for about 2.2 ms and the clock
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* is typically written with a precision of 1 jiffy, trying
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* to obtain a precision better than a few milliseconds is
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* an illusion. Only consistency is interesting, this also
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* allows to use the routine for /dev/rtc without a potential
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* 1 second kernel busy loop triggered by any reader of /dev/rtc.
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*/
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for (i = 0; i<1000000; i++) {
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uip = maple_clock_read(RTC_FREQ_SELECT);
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tm->tm_sec = maple_clock_read(RTC_SECONDS);
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tm->tm_min = maple_clock_read(RTC_MINUTES);
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tm->tm_hour = maple_clock_read(RTC_HOURS);
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tm->tm_mday = maple_clock_read(RTC_DAY_OF_MONTH);
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tm->tm_mon = maple_clock_read(RTC_MONTH);
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tm->tm_year = maple_clock_read(RTC_YEAR);
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uip |= maple_clock_read(RTC_FREQ_SELECT);
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if ((uip & RTC_UIP)==0)
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break;
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}
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if (!(maple_clock_read(RTC_CONTROL) & RTC_DM_BINARY)
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|| RTC_ALWAYS_BCD) {
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BCD_TO_BIN(tm->tm_sec);
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BCD_TO_BIN(tm->tm_min);
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BCD_TO_BIN(tm->tm_hour);
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BCD_TO_BIN(tm->tm_mday);
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BCD_TO_BIN(tm->tm_mon);
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BCD_TO_BIN(tm->tm_year);
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}
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if ((tm->tm_year + 1900) < 1970)
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tm->tm_year += 100;
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GregorianDay(tm);
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}
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int maple_set_rtc_time(struct rtc_time *tm)
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{
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unsigned char save_control, save_freq_select;
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int sec, min, hour, mon, mday, year;
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spin_lock(&rtc_lock);
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save_control = maple_clock_read(RTC_CONTROL); /* tell the clock it's being set */
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maple_clock_write((save_control|RTC_SET), RTC_CONTROL);
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save_freq_select = maple_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
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maple_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
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sec = tm->tm_sec;
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min = tm->tm_min;
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hour = tm->tm_hour;
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mon = tm->tm_mon;
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mday = tm->tm_mday;
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year = tm->tm_year;
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if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
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BIN_TO_BCD(sec);
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BIN_TO_BCD(min);
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BIN_TO_BCD(hour);
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BIN_TO_BCD(mon);
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BIN_TO_BCD(mday);
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BIN_TO_BCD(year);
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}
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maple_clock_write(sec, RTC_SECONDS);
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maple_clock_write(min, RTC_MINUTES);
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maple_clock_write(hour, RTC_HOURS);
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maple_clock_write(mon, RTC_MONTH);
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maple_clock_write(mday, RTC_DAY_OF_MONTH);
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maple_clock_write(year, RTC_YEAR);
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/* The following flags have to be released exactly in this order,
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* otherwise the DS12887 (popular MC146818A clone with integrated
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* battery and quartz) will not reset the oscillator and will not
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* update precisely 500 ms later. You won't find this mentioned in
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* 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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maple_clock_write(save_control, RTC_CONTROL);
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maple_clock_write(save_freq_select, RTC_FREQ_SELECT);
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spin_unlock(&rtc_lock);
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return 0;
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}
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unsigned long __init maple_get_boot_time(void)
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{
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struct rtc_time tm;
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struct device_node *rtcs;
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rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
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if (rtcs && rtcs->addrs) {
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maple_rtc_addr = rtcs->addrs[0].address;
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printk(KERN_INFO "Maple: Found RTC at 0x%x\n", maple_rtc_addr);
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} else {
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maple_rtc_addr = RTC_PORT(0); /* legacy address */
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printk(KERN_INFO "Maple: No device node for RTC, assuming "
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"legacy address (0x%x)\n", maple_rtc_addr);
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}
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maple_get_rtc_time(&tm);
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return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
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tm.tm_hour, tm.tm_min, tm.tm_sec);
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}
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