/* * 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; }