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 /*
  * This file interfaces with the real-time clock found in a
  * Dallas Semiconductor DS1307/DS1308 serial real-time clock chip.
  * This RTC have I2C bus interface. BSP have to provide I2C bus primitives
  * to make this driver working. getRegister and setRegister primitives is
  * not used here to avoid multiple transactions over I2C bus (each transaction
  * require significant time and error when date/time information red may
  * occurs). ulControlPort contains I2C bus number; ulDataPort contains
  * RTC I2C device address.
  *
  * Year 2000 Note:
  *
  * 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 00-87 are mapped to 2000-2087
  *    + two digit years 88-99 are mapped to 1988-1999
  */
 
 /*
  * Copyright (C) 2000 OKTET Ltd., St.-Petersburg, Russia
  * Author: Victor V. Vengerov <vvv@oktet.ru>
  *
  * The license and distribution terms for this file may be
  * found in the file LICENSE in this distribution or at
  * http://www.rtems.org/license/LICENSE.
  */
 
 #include <rtems.h>
 #include <libchip/rtc.h>
 #include <string.h>
 #include "ds1307.h"
 #include "i2c.h"
 
 /* Convert from/to Binary-Coded Decimal representation */
 #define From_BCD( _x ) ((((_x) >> 4) * 10) + ((_x) & 0x0F))
 #define To_BCD( _x )   ((((_x) / 10) << 4) + ((_x) % 10))
 
 /* ds1307_initialize --
  *     Initialize DS1307 real-time clock chip. If RTC is halted, this
  *     function resume counting.
  *
  * PARAMETERS:
  *     minor -- minor RTC device number
  */
 static void ds1307_initialize(int minor)
 {
   i2c_message_status status;
   int try;
   uint8_t         sec;
   i2c_bus_number bus;
   i2c_address addr;
 
   bus = RTC_Table[minor].ulCtrlPort1;
   addr = RTC_Table[minor].ulDataPort;
 
   /* Read SECONDS register */
   try = 0;
   do {
     status = i2c_wbrd(bus, addr, 0, &sec, sizeof(sec));
     try++;
   } while ((status != I2C_SUCCESSFUL) && (try < 15));
 
   /* If clock is halted, reset and start the clock */
   if ((sec & DS1307_SECOND_HALT) != 0) {
       uint8_t         start[8];
       memset(start, 0, sizeof(start));
       start[0] = DS1307_SECOND;
       try = 0;
       do {
       status = i2c_write(bus, addr, start, 2);
       } while ((status != I2C_SUCCESSFUL) && (try < 15));
   }
 }
 
 /* ds1307_get_time --
  *     read current time from DS1307 real-time clock chip and convert it
  *     to the rtems_time_of_day structure.
  *
  * PARAMETERS:
  *     minor -- minor RTC device number
  *     time -- place to put return value (date and time)
  *
  * RETURNS:
  *     0, if time obtained successfully
  *     -1, if error occured
  */
 static int ds1307_get_time(int minor, rtems_time_of_day *time)
 {
   i2c_bus_number bus;
   i2c_address addr;
   uint8_t         info[8];
   uint32_t         v1, v2;
   i2c_message_status status;
   int try;
 
   if (time == NULL)
     return -1;
 
   bus = RTC_Table[minor].ulCtrlPort1;
   addr = RTC_Table[minor].ulDataPort;
 
   memset(time, 0, sizeof(rtems_time_of_day));
   try = 0;
   do {
     status = i2c_wbrd(bus, addr, 0, info, sizeof(info));
     try++;
   } while ((status != I2C_SUCCESSFUL) && (try < 10));
 
   if (status != I2C_SUCCESSFUL) {
     return -1;
   }
 
   v1 = info[DS1307_YEAR];
   v2 = From_BCD(v1);
   if (v2 < 88)
     time->year = 2000 + v2;
   else
     time->year = 1900 + v2;
 
   v1 = info[DS1307_MONTH] & ~0xE0;
   time->month = From_BCD(v1);
 
   v1 = info[DS1307_DAY] & ~0xC0;
   time->day = From_BCD(v1);
 
   v1 = info[DS1307_HOUR];
   if (v1 & DS1307_HOUR_12) {
     v2 = v1 & ~0xE0;
     if (v1 & DS1307_HOUR_PM) {
       time->hour = From_BCD(v2) + 12;
     } else {
       time->hour = From_BCD(v2);
     }
   } else {
     v2 = v1 & ~0xC0;
     time->hour = From_BCD(v2);
   }
 
   v1 = info[DS1307_MINUTE] & ~0x80;
   time->minute = From_BCD(v1);
 
   v1 = info[DS1307_SECOND];
   v2 = v1 & ~0x80;
   time->second = From_BCD(v2);
 
   return 0;
 }
 
 /* ds1307_set_time --
  *     set time to the DS1307 real-time clock chip
  *
  * PARAMETERS:
  *     minor -- minor RTC device number
  *     time -- new date and time to be written to DS1307
  *
  * RETURNS:
  *     0, if time obtained successfully
  *     -1, if error occured
  */
 static int ds1307_set_time(int minor, const rtems_time_of_day *time)
 {
   i2c_bus_number bus;
   i2c_address addr;
   uint8_t         info[8];
   i2c_message_status status;
   int try;
 
   if (time == NULL)
     return -1;
 
   bus = RTC_Table[minor].ulCtrlPort1;
   addr = RTC_Table[minor].ulDataPort;
 
   if (time->year >= 2088)
       rtems_fatal_error_occurred(RTEMS_INVALID_NUMBER);
 
   info[0] = DS1307_SECOND;
   info[1 + DS1307_YEAR] = To_BCD(time->year % 100);
   info[1 + DS1307_MONTH] = To_BCD(time->month);
   info[1 + DS1307_DAY] = To_BCD(time->day);
   info[1 + DS1307_HOUR] = To_BCD(time->hour);
   info[1 + DS1307_MINUTE] = To_BCD(time->minute);
   info[1 + DS1307_SECOND] = To_BCD(time->second);
   info[1 + DS1307_DAY_OF_WEEK] = 1; /* Do not set day of week */
 
   try = 0;
   do {
     status = i2c_write(bus, addr, info, 8);
     try++;
   } while ((status != I2C_SUCCESSFUL) && (try < 10));
 
   if (status != I2C_SUCCESSFUL)
     return -1;
   else
     return 0;
 }
 
 /* Driver function table */
 
 rtc_fns ds1307_fns = {
   ds1307_initialize,
   ds1307_get_time,
   ds1307_set_time
 };

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