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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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