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/* SPDX-License-Identifier: BSD-2-Clause */
/*
* This file interfaces with the real-time clock found in
* a Motorola MC146818A (common on PC hardware)
*
* Year 2K Notes:
*
* This chip only uses a two digit field to store the year. This
* code uses the RTEMS Epoch as a pivot year. This lets us map the
* two digit year field as follows:
*
* + two digit years 0-87 are mapped to 2000-2087.
* + two digit years 88-99 are mapped to 1988-1999.
*
* This is less than the time span supported by RTEMS.
*
* COPYRIGHT (c) 1989-1999.
* On-Line Applications Research Corporation (OAR).
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <rtems.h>
#include <libchip/rtc.h>
#include <libchip/mc146818a.h>
#define From_BCD( _x ) ((((_x) >> 4) * 10) + ((_x) & 0x0F))
#define To_BCD( _x ) ((((_x) / 10) << 4) + ((_x) % 10))
/*
* See if chip is present
*/
bool mc146818a_probe(
int minor
)
{
uint32_t mc146818a;
getRegister_f getReg;
uint32_t value;
/*
* Verify that chip is present and that time is valid
*/
mc146818a = RTC_Table[ minor ].ulCtrlPort1;
getReg = RTC_Table[ minor ].getRegister;
value = (*getReg)( mc146818a, MC146818A_STATUSD );
if ((value == 0) || (value == 0xFF))
return false;
return true;
}
/*
* Initialize chip
*/
static void mc146818a_initialize(
int minor
)
{
uintptr_t mc146818a;
setRegister_f setReg;
mc146818a = RTC_Table[ minor ].ulCtrlPort1;
setReg = RTC_Table[ minor ].setRegister;
(*setReg)(
mc146818a,
MC146818A_STATUSA,
MC146818ASA_DIVIDER|MC146818ASA_1024
);
(*setReg)(
mc146818a,
MC146818A_STATUSB,
MC146818ASB_24HR
);
}
/*
* Read time from chip
*/
static int mc146818a_get_time(
int minor,
rtems_time_of_day *time
)
{
uintptr_t mc146818a;
getRegister_f getReg;
uint32_t value;
rtems_interrupt_level level;
mc146818a = RTC_Table[ minor ].ulCtrlPort1;
getReg = RTC_Table[ minor ].getRegister;
/*
* No time if power failed
*/
if (((*getReg)( mc146818a, MC146818A_STATUSD ) & MC146818ASD_PWR) == 0)
return -1;
/*
* Wait for time update to complete
*/
rtems_interrupt_disable( level );
while (((*getReg)( mc146818a, MC146818A_STATUSA ) & MC146818ASA_TUP) != 0) {
rtems_interrupt_flash( level );
}
/*
* Read the time (we have at least 244 usec to do this)
*/
value = (*getReg)( mc146818a, MC146818A_YEAR );
value = From_BCD( value );
if ( value < 88 )
time->year = 2000 + value;
else
time->year = 1900 + value;
value = (*getReg)( mc146818a, MC146818A_MONTH );
time->month = From_BCD( value );
value = (*getReg)( mc146818a, MC146818A_DAY );
time->day = From_BCD( value );
value = (*getReg)( mc146818a, MC146818A_HRS );
time->hour = From_BCD( value );
value = (*getReg)( mc146818a, MC146818A_MIN );
time->minute = From_BCD( value );
value = (*getReg)( mc146818a, MC146818A_SEC );
rtems_interrupt_enable( level );
time->second = From_BCD( value );
time->ticks = 0;
return 0;
}
/*
* Set time into chip
*/
static int mc146818a_set_time(
int minor,
const rtems_time_of_day *time
)
{
uint32_t mc146818a;
setRegister_f setReg;
mc146818a = RTC_Table[ minor ].ulCtrlPort1;
setReg = RTC_Table[ minor ].setRegister;
/*
* Stop the RTC
*/
(*setReg)( mc146818a, MC146818A_STATUSB, MC146818ASB_HALT|MC146818ASB_24HR );
if ( time->year >= 2088 )
rtems_fatal_error_occurred( RTEMS_INVALID_NUMBER );
(*setReg)( mc146818a, MC146818A_YEAR, To_BCD(time->year % 100) );
(*setReg)( mc146818a, MC146818A_MONTH, To_BCD(time->month) );
(*setReg)( mc146818a, MC146818A_DAY, To_BCD(time->day) );
(*setReg)( mc146818a, MC146818A_HRS, To_BCD(time->hour) );
(*setReg)( mc146818a, MC146818A_MIN, To_BCD(time->minute) );
(*setReg)( mc146818a, MC146818A_SEC, To_BCD(time->second) );
/*
* Restart the RTC
*/
(*setReg)( mc146818a, MC146818A_STATUSB, MC146818ASB_24HR );
return 0;
}
/*
* Driver function table
*/
rtc_fns mc146818a_fns = {
mc146818a_initialize,
mc146818a_get_time,
mc146818a_set_time
};
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