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libpayload: Improve rtc functions 

On Lenovo T500 the RTC readings where wrong, as RTC has
different encodings, depending on the statusB register.

Support BCD vs binary RTC format and AM/PM vs 24h RTC format.

Fixes wrong date and time on Lenovo 500.

Change-Id: Id773c33e228973e190a7e14c3d11979678b1a619
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/18498
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
This commit is contained in:
Patrick Rudolph 2017-02-25 09:56:53 +01:00 committed by Patrick Georgi
parent ef613b97cf
commit 9f3e734e5c
2 changed files with 41 additions and 9 deletions
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47
payloads/libpayload/drivers/nvram.c
View File

@ -2,6 +2,7 @@
* This file is part of the libpayload project.
*
* Copyright (C) 2008 Uwe Hermann <uwe@hermann-uwe.de>
* Copyright (C) 2017 Patrick Rudolph <siro@das-labor.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -111,23 +112,51 @@ int nvram_updating(void)
*/
void rtc_read_clock(struct tm *time)
{
u16 timeout = 10000;
u8 statusB;
u8 reg8;
memset(time, 0, sizeof(*time));
while(nvram_updating());
while (nvram_updating())
if (!timeout--)
return;
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));
statusB = nvram_read(NVRAM_RTC_STATUSB);
if (!(statusB & NVRAM_RTC_FORMAT_BINARY)) {
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));
if (!(statusB & NVRAM_RTC_FORMAT_24HOUR)) {
reg8 = nvram_read(NVRAM_RTC_HOURS);
time->tm_hour = bcd2dec(reg8 & 0x7f);
time->tm_hour += (reg8 & 0x80) ? 12 : 0;
time->tm_hour %= 24;
} else
time->tm_hour = bcd2dec(nvram_read(NVRAM_RTC_HOURS));
time->tm_year = bcd2dec(nvram_read(NVRAM_RTC_YEAR));
} else {
time->tm_mon = nvram_read(NVRAM_RTC_MONTH) - 1;
time->tm_sec = nvram_read(NVRAM_RTC_SECONDS);
time->tm_min = nvram_read(NVRAM_RTC_MINUTES);
time->tm_mday = nvram_read(NVRAM_RTC_DAY);
if (!(statusB & NVRAM_RTC_FORMAT_24HOUR)) {
reg8 = nvram_read(NVRAM_RTC_HOURS);
time->tm_hour = reg8 & 0x7f;
time->tm_hour += (reg8 & 0x80) ? 12 : 0;
time->tm_hour %= 24;
} else
time->tm_hour = nvram_read(NVRAM_RTC_HOURS);
time->tm_year = nvram_read(NVRAM_RTC_YEAR);
}
/* 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;
}

3
payloads/libpayload/include/libpayload.h
View File

@ -130,6 +130,9 @@ static const char _pstruct(key)[] \
#define NVRAM_RTC_YEAR 9 /**< RTC Year offset in CMOS */
#define NVRAM_RTC_FREQ_SELECT 10 /**< RTC Update Status Register */
#define NVRAM_RTC_UIP 0x80
#define NVRAM_RTC_STATUSB 11 /**< RTC Status Register B */
#define NVRAM_RTC_FORMAT_24HOUR 0x02
#define NVRAM_RTC_FORMAT_BINARY 0x04
/** Broken down time structure */
struct tm {