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[time] Add RTC-based time source

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Add a time source using the CMOS RTC to obtain the current time.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2012-03-19 17:08:51 +00:00
parent 846bde90e6
commit 12002d6955
6 changed files with 242 additions and 40 deletions
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2
src/arch/i386/include/bits/time.h
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@ -9,4 +9,6 @@
FILE_LICENCE ( GPL2_OR_LATER );
#include <ipxe/rtc_time.h>
#endif /* _BITS_TIME_H */

18
src/arch/i386/include/ipxe/rtc_time.h Normal file
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@ -0,0 +1,18 @@
#ifndef _IPXE_RTC_TIME_H
#define _IPXE_RTC_TIME_H
/** @file
*
* RTC-based time source
*
*/
FILE_LICENCE ( GPL2_OR_LATER );
#ifdef TIME_RTC
#define TIME_PREFIX_rtc
#else
#define TIME_PREFIX_rtc __rtc_
#endif
#endif /* _IPXE_RTC_TIME_H */

83
src/arch/i386/include/rtc.h Normal file
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@ -0,0 +1,83 @@
#ifndef _RTC_H
#define _RTC_H
/** @file
*
* CMOS Real-Time Clock (RTC)
*
* The CMOS/RTC registers are documented (with varying degrees of
* accuracy and consistency) at
*
* http://www.nondot.org/sabre/os/files/MiscHW/RealtimeClockFAQ.txt
* http://wiki.osdev.org/RTC
* http://wiki.osdev.org/CMOS
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <pic8259.h>
/** RTC IRQ */
#define RTC_IRQ 8
/** RTC interrupt vector */
#define RTC_INT IRQ_INT ( RTC_IRQ )
/** CMOS/RTC address (and NMI) register */
#define CMOS_ADDRESS 0x70
/** NMI disable bit */
#define CMOS_DISABLE_NMI 0x80
/** CMOS/RTC data register */
#define CMOS_DATA 0x71
/** RTC seconds */
#define RTC_SEC 0x00
/** RTC minutes */
#define RTC_MIN 0x02
/** RTC hours */
#define RTC_HOUR 0x04
/** RTC weekday */
#define RTC_WDAY 0x06
/** RTC day of month */
#define RTC_MDAY 0x07
/** RTC month */
#define RTC_MON 0x08
/** RTC year */
#define RTC_YEAR 0x09
/** RTC status register A */
#define RTC_STATUS_A 0x0a
/** RTC update in progress bit */
#define RTC_STATUS_A_UPDATE_IN_PROGRESS 0x80
/** RTC status register B */
#define RTC_STATUS_B 0x0b
/** RTC 24 hour format bit */
#define RTC_STATUS_B_24_HOUR 0x02
/** RTC binary mode bit */
#define RTC_STATUS_B_BINARY 0x04
/** RTC Periodic Interrupt Enabled bit */
#define RTC_STATUS_B_PIE 0x40
/** RTC status register C */
#define RTC_STATUS_C 0x0c
/** RTC status register D */
#define RTC_STATUS_D 0x0d
/** CMOS default address */
#define CMOS_DEFAULT_ADDRESS RTC_STATUS_D
#endif /* _RTC_H */

40
src/arch/i386/interface/pcbios/rtc_entropy.c
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@ -22,53 +22,15 @@ FILE_LICENCE ( GPL2_OR_LATER );
*
* RTC-based entropy source
*
* The CMOS/RTC registers are documented (with varying degrees of
* accuracy and consistency) at
*
* http://www.nondot.org/sabre/os/files/MiscHW/RealtimeClockFAQ.txt
* http://wiki.osdev.org/RTC
* http://wiki.osdev.org/CMOS
*/
#include <stdint.h>
#include <string.h>
#include <biosint.h>
#include <pic8259.h>
#include <rtc.h>
#include <ipxe/entropy.h>
/** RTC IRQ */
#define RTC_IRQ 8
/** RTC interrupt vector */
#define RTC_INT IRQ_INT ( RTC_IRQ )
/** CMOS/RTC address (and NMI) register */
#define CMOS_ADDRESS 0x70
/** NMI disable bit */
#define CMOS_DISABLE_NMI 0x80
/** CMOS/RTC data register */
#define CMOS_DATA 0x71
/** RTC status register A */
#define RTC_STATUS_A 0x0a
/** RTC status register B */
#define RTC_STATUS_B 0x0b
/** RTC Periodic Interrupt Enabled bit */
#define RTC_STATUS_B_PIE 0x40
/** RTC status register C */
#define RTC_STATUS_C 0x0c
/** RTC status register D */
#define RTC_STATUS_D 0x0d
/** CMOS default address */
#define CMOS_DEFAULT_ADDRESS RTC_STATUS_D
/** RTC "interrupt triggered" flag */
static uint8_t __text16 ( rtc_flag );
#define rtc_flag __use_text16 ( rtc_flag )

137
src/arch/i386/interface/pcbios/rtc_time.c Normal file
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@ -0,0 +1,137 @@
/*
* Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
FILE_LICENCE ( GPL2_OR_LATER );
/** @file
*
* RTC-based time source
*
*/
#include <stdint.h>
#include <time.h>
#include <rtc.h>
#include <ipxe/time.h>
/**
* Read RTC register
*
* @v address Register address
* @ret data Data
*/
static unsigned int rtc_readb ( int address ) {
outb ( address, CMOS_ADDRESS );
return inb ( CMOS_DATA );
}
/**
* Check if RTC update is in progress
*
* @ret is_busy RTC update is in progress
*/
static int rtc_is_busy ( void ) {
return ( rtc_readb ( RTC_STATUS_A ) & RTC_STATUS_A_UPDATE_IN_PROGRESS );
}
/**
* Read RTC BCD register
*
* @v address Register address
* @ret value Value
*/
static unsigned int rtc_readb_bcd ( int address ) {
unsigned int bcd;
bcd = rtc_readb ( address );
return ( bcd - ( 6 * ( bcd >> 4 ) ) );
}
/**
* Read RTC time
*
* @ret time Time, in seconds
*/
static time_t rtc_read_time ( void ) {
unsigned int status_b;
int is_binary;
int is_24hour;
unsigned int ( * read_component ) ( int address );
struct tm tm;
int is_pm;
unsigned int hour;
time_t time;
/* Wait for any in-progress update to complete */
while ( rtc_is_busy() ) {}
/* Determine RTC mode */
status_b = rtc_readb ( RTC_STATUS_B );
is_binary = ( status_b & RTC_STATUS_B_BINARY );
is_24hour = ( status_b & RTC_STATUS_B_24_HOUR );
read_component = ( is_binary ? rtc_readb : rtc_readb_bcd );
/* Read time values */
tm.tm_sec = read_component ( RTC_SEC );
tm.tm_min = read_component ( RTC_MIN );
hour = read_component ( RTC_HOUR );
if ( ! is_24hour ) {
is_pm = ( hour >= 80 );
hour = ( ( ( ( hour & 0x7f ) % 80 ) % 12 ) +
( is_pm ? 12 : 0 ) );
}
tm.tm_hour = hour;
tm.tm_mday = read_component ( RTC_MDAY );
tm.tm_mon = ( read_component ( RTC_MON ) - 1 );
tm.tm_year = ( read_component ( RTC_YEAR ) +
100 /* Assume we are in the 21st century, since
* this code was written in 2012 */ );
DBGC ( RTC_STATUS_A, "RTCTIME is %04d-%02d-%02d %02d:%02d:%02d "
"(%s,%d-hour)\n", ( tm.tm_year + 1900 ), ( tm.tm_mon + 1 ),
tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec,
( is_binary ? "binary" : "BCD" ), ( is_24hour ? 24 : 12 ) );
/* Convert to seconds since the Epoch */
time = mktime ( &tm );
return time;
}
/**
* Get current time in seconds
*
* @ret time Time, in seconds
*/
static time_t rtc_now ( void ) {
time_t time = 0;
time_t last_time;
/* Read time until we get two matching values in a row, in
* case we end up reading a corrupted value in the middle of
* an update.
*/
do {
last_time = time;
time = rtc_read_time();
} while ( time != last_time );
return time;
}
PROVIDE_TIME ( rtc, time_now, rtc_now );

2
src/config/defaults/pcbios.h
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@ -19,7 +19,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
#define SMBIOS_PCBIOS
#define SANBOOT_PCBIOS
#define ENTROPY_RTC
#define TIME_NULL
#define TIME_RTC
#define IMAGE_ELF /* ELF image support */
#define IMAGE_MULTIBOOT /* MultiBoot image support */