143 lines
3.6 KiB
C
143 lines
3.6 KiB
C
/*
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* Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* You can also choose to distribute this program under the terms of
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* the Unmodified Binary Distribution Licence (as given in the file
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* COPYING.UBDL), provided that you have satisfied its requirements.
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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/** @file
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*
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* RTC-based time source
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*
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*/
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#include <stdint.h>
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#include <time.h>
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#include <rtc.h>
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#include <ipxe/time.h>
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/**
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* Read RTC register
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*
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* @v address Register address
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* @ret data Data
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*/
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static unsigned int rtc_readb ( int address ) {
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outb ( address, CMOS_ADDRESS );
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return inb ( CMOS_DATA );
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}
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/**
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* Check if RTC update is in progress
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*
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* @ret is_busy RTC update is in progress
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*/
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static int rtc_is_busy ( void ) {
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return ( rtc_readb ( RTC_STATUS_A ) & RTC_STATUS_A_UPDATE_IN_PROGRESS );
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}
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/**
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* Read RTC BCD register
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*
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* @v address Register address
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* @ret value Value
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*/
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static unsigned int rtc_readb_bcd ( int address ) {
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unsigned int bcd;
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bcd = rtc_readb ( address );
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return ( bcd - ( 6 * ( bcd >> 4 ) ) );
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}
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/**
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* Read RTC time
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*
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* @ret time Time, in seconds
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*/
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static time_t rtc_read_time ( void ) {
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unsigned int status_b;
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int is_binary;
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int is_24hour;
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unsigned int ( * read_component ) ( int address );
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struct tm tm;
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int is_pm;
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unsigned int hour;
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time_t time;
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/* Wait for any in-progress update to complete */
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while ( rtc_is_busy() ) {}
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/* Determine RTC mode */
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status_b = rtc_readb ( RTC_STATUS_B );
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is_binary = ( status_b & RTC_STATUS_B_BINARY );
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is_24hour = ( status_b & RTC_STATUS_B_24_HOUR );
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read_component = ( is_binary ? rtc_readb : rtc_readb_bcd );
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/* Read time values */
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tm.tm_sec = read_component ( RTC_SEC );
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tm.tm_min = read_component ( RTC_MIN );
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hour = read_component ( RTC_HOUR );
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if ( ! is_24hour ) {
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is_pm = ( hour >= 80 );
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hour = ( ( ( ( hour & 0x7f ) % 80 ) % 12 ) +
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( is_pm ? 12 : 0 ) );
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}
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tm.tm_hour = hour;
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tm.tm_mday = read_component ( RTC_MDAY );
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tm.tm_mon = ( read_component ( RTC_MON ) - 1 );
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tm.tm_year = ( read_component ( RTC_YEAR ) +
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100 /* Assume we are in the 21st century, since
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* this code was written in 2012 */ );
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DBGC ( RTC_STATUS_A, "RTCTIME is %04d-%02d-%02d %02d:%02d:%02d "
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"(%s,%d-hour)\n", ( tm.tm_year + 1900 ), ( tm.tm_mon + 1 ),
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tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec,
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( is_binary ? "binary" : "BCD" ), ( is_24hour ? 24 : 12 ) );
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/* Convert to seconds since the Epoch */
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time = mktime ( &tm );
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return time;
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}
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/**
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* Get current time in seconds
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*
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* @ret time Time, in seconds
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*/
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static time_t rtc_now ( void ) {
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time_t time = 0;
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time_t last_time;
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/* Read time until we get two matching values in a row, in
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* case we end up reading a corrupted value in the middle of
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* an update.
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*/
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do {
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last_time = time;
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time = rtc_read_time();
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} while ( time != last_time );
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return time;
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}
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PROVIDE_TIME ( rtc, time_now, rtc_now );
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