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/*
* This file is part of the libpayload project.
*
* Copyright (C) 2008 Uwe Hermann <uwe@hermann-uwe.de>
*
* 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
/*
* Datasheet:
* - Name: MC146818: Real-time Clock Plus RAM (RTC)
* - PDF: http://www.freescale.com/files/microcontrollers/doc/data_sheet/MC146818.pdf
* - Order number: MC146818/D
*/
/*
* See also:
* http://bochs.sourceforge.net/techspec/CMOS-reference.txt
* http://www.bioscentral.com/misc/cmosmap.htm
*/
#include <libpayload-config.h>
#include <libpayload.h>
/**
* PCs can have either 64 (very old ones), 128, or 256 bytes of CMOS RAM.
*
* Usually you access the lower 128 CMOS bytes via I/O port 0x70/0x71.
* For more recent chipsets with 256 bytes, you have to access the upper
* 128 bytes (128-255) using two different registers, usually 0x72/0x73.
*
* On some chipsets this can be different, though. The VIA VT8237R for example
* only recognizes the ports 0x74/0x75 for accessing the high 128 CMOS bytes
* (as seems to be the case for multiple VIA chipsets).
*
* It's very chipset-specific if and how the upper 128 bytes are enabled at
* all, but this work should be done in coreboot anyway. Libpayload assumes
* that coreboot has properly enabled access to the upper 128 bytes and
* doesn't try to do this on its own.
*/
#define RTC_PORT_STANDARD 0x70
#ifdef CONFIG_RTC_PORT_EXTENDED_VIA
#define RTC_PORT_EXTENDED 0x74
#else
#define RTC_PORT_EXTENDED 0x72
#endif
/**
* Read a byte from the specified NVRAM address.
*
* @param addr The NVRAM address to read a byte from.
* @return The byte at the given NVRAM address.
*/
u8 nvram_read(u8 addr)
{
u16 rtc_port = addr < 128 ? RTC_PORT_STANDARD : RTC_PORT_EXTENDED;
outb(addr, rtc_port);
return inb(rtc_port + 1);
}
/**
* Write a byte to the specified NVRAM address.
*
* @param val The byte to write to NVRAM.
* @param addr The NVRAM address to write to.
*/
void nvram_write(u8 val, u8 addr)
{
u16 rtc_port = addr < 128 ? RTC_PORT_STANDARD : RTC_PORT_EXTENDED;
outb(addr, rtc_port);
outb(val, rtc_port + 1);
}
/**
* Return 1 if the NVRAM is currently updating and a 0 otherwise
* @return A 1 if the NVRAM is updating and 0 otherwise
*/
int nvram_updating(void)
{
return (nvram_read(NVRAM_RTC_FREQ_SELECT) & NVRAM_RTC_UIP) ? 1 : 0;
}
/**
* Get the current time and date from the RTC
*
* @param time A pointer to a broken-down time structure
*/
void rtc_read_clock(struct tm *time)
{
memset(time, 0, sizeof(*time));
while(nvram_updating());
time->tm_mon = bcd2dec(nvram_read(NVRAM_RTC_MONTH)) - 1;
time->tm_sec = bcd2dec(nvram_read(NVRAM_RTC_SECONDS));
time->tm_min = bcd2dec(nvram_read(NVRAM_RTC_MINUTES));
time->tm_mday = bcd2dec(nvram_read(NVRAM_RTC_DAY));
time->tm_hour = bcd2dec(nvram_read(NVRAM_RTC_HOURS));
/* Instead of finding the century register,
we just make an assumption that if the year value is
less then 80, then it is 2000+
*/
time->tm_year = bcd2dec(nvram_read(NVRAM_RTC_YEAR));
if (time->tm_year < 80)
time->tm_year += 100;
}
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