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/* arch/sh/kernel/rtc-aica.c
*
* Dreamcast AICA RTC routines.
*
* Copyright (c) 2001 M. R. Brown <mrbrown@0xd6.org>
*
* Released under the terms of the GNU GPL v2.0.
*
*/
#include <linux/time.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
* @tv: pointer to resulting timeval
*
* Grabs the current RTC seconds counter and adjusts it to the Unix Epoch.
*/
void aica_rtc_gettimeofday(struct timeval *tv) {
unsigned long val1, val2;
do {
val1 = ((ctrl_inl(AICA_RTC_SECS_H) & 0xffff) << 16) |
(ctrl_inl(AICA_RTC_SECS_L) & 0xffff);
val2 = ((ctrl_inl(AICA_RTC_SECS_H) & 0xffff) << 16) |
(ctrl_inl(AICA_RTC_SECS_L) & 0xffff);
} while (val1 != val2);
tv->tv_sec = val1 - TWENTY_YEARS;
/* Can't get microseconds with just a seconds counter. */
tv->tv_usec = 0;
}
/**
* aica_rtc_settimeofday - Set the AICA RTC to the current time
* @tv: contains the timeval to set
*
* Adjusts the given @tv to the AICA Epoch and sets the RTC seconds counter.
*/
int aica_rtc_settimeofday(const struct timeval *tv) {
unsigned long val1, val2;
unsigned long secs = tv->tv_sec + TWENTY_YEARS;
do {
ctrl_outl((secs & 0xffff0000) >> 16, AICA_RTC_SECS_H);
ctrl_outl((secs & 0xffff), AICA_RTC_SECS_L);
val1 = ((ctrl_inl(AICA_RTC_SECS_H) & 0xffff) << 16) |
(ctrl_inl(AICA_RTC_SECS_L) & 0xffff);
val2 = ((ctrl_inl(AICA_RTC_SECS_H) & 0xffff) << 16) |
(ctrl_inl(AICA_RTC_SECS_L) & 0xffff);
} while (val1 != val2);
return 0;
}
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