82 lines
2.1 KiB
C
82 lines
2.1 KiB
C
/*
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* arch/sh/boards/dreamcast/rtc.c
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*
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* Dreamcast AICA RTC routines.
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*
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* Copyright (c) 2001, 2002 M. R. Brown <mrbrown@0xd6.org>
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* Copyright (c) 2002 Paul Mundt <lethal@chaoticdreams.org>
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*
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* Released under the terms of the GNU GPL v2.0.
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*
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*/
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#include <linux/time.h>
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#include <asm/rtc.h>
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#include <asm/io.h>
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/* The AICA RTC has an Epoch of 1/1/1950, so we must subtract 20 years (in
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seconds) to get the standard Unix Epoch when getting the time, and add
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20 years when setting the time. */
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#define TWENTY_YEARS ((20 * 365LU + 5) * 86400)
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/* The AICA RTC is represented by a 32-bit seconds counter stored in 2 16-bit
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registers.*/
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#define AICA_RTC_SECS_H 0xa0710000
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#define AICA_RTC_SECS_L 0xa0710004
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/**
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* aica_rtc_gettimeofday - Get the time from the AICA RTC
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* @ts: pointer to resulting timespec
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*
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* Grabs the current RTC seconds counter and adjusts it to the Unix Epoch.
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*/
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static void aica_rtc_gettimeofday(struct timespec *ts)
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{
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unsigned long val1, val2;
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do {
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val1 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) |
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(__raw_readl(AICA_RTC_SECS_L) & 0xffff);
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val2 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) |
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(__raw_readl(AICA_RTC_SECS_L) & 0xffff);
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} while (val1 != val2);
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ts->tv_sec = val1 - TWENTY_YEARS;
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/* Can't get nanoseconds with just a seconds counter. */
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ts->tv_nsec = 0;
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}
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/**
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* aica_rtc_settimeofday - Set the AICA RTC to the current time
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* @secs: contains the time_t to set
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*
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* Adjusts the given @tv to the AICA Epoch and sets the RTC seconds counter.
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*/
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static int aica_rtc_settimeofday(const time_t secs)
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{
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unsigned long val1, val2;
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unsigned long adj = secs + TWENTY_YEARS;
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do {
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__raw_writel((adj & 0xffff0000) >> 16, AICA_RTC_SECS_H);
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__raw_writel((adj & 0xffff), AICA_RTC_SECS_L);
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val1 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) |
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(__raw_readl(AICA_RTC_SECS_L) & 0xffff);
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val2 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) |
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(__raw_readl(AICA_RTC_SECS_L) & 0xffff);
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} while (val1 != val2);
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return 0;
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}
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void aica_time_init(void)
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{
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rtc_sh_get_time = aica_rtc_gettimeofday;
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rtc_sh_set_time = aica_rtc_settimeofday;
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}
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