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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.h>
#define RTC_PORT 0x70
/**
* 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)
{
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)
{
outb(addr, RTC_PORT);
outb(val, RTC_PORT + 1);
}
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