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