/*
* 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
};
