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>
diff --git a/payloads/libpayload/drivers/nvram.c b/payloads/libpayload/drivers/nvram.c
index a116d1b..34ee033 100644
--- a/payloads/libpayload/drivers/nvram.c
+++ b/payloads/libpayload/drivers/nvram.c
@@ -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 @@
*/
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;
}
diff --git a/payloads/libpayload/include/libpayload.h b/payloads/libpayload/include/libpayload.h
index 4b6a250..7496972 100644
--- a/payloads/libpayload/include/libpayload.h
+++ b/payloads/libpayload/include/libpayload.h
@@ -130,6 +130,9 @@
#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 {