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path: root/drivers/rtc/rtc-mc146818-lib.c
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2020-01-04rtc: cmos: Revert "rtc: Fix the AltCentury value on AMD/Hygon platform"Alexandre Belloni
There are multiple reports of this patch breaking RTC time setting for AMD platforms. This reverts commit 7ad295d5196a58c22abecef62dd4f99e2f86e831. Cc: Jinke Fan <fanjinke@hygon.cn> Link: https://lore.kernel.org/r/CABXGCsMLob0DC25JS8wwAYydnDoHBSoMh2_YLPfqm3TTvDE-Zw@mail.gmail.com Fixes: 7ad295d5196a ("rtc: Fix the AltCentury value on AMD/Hygon platform") Link: https://lore.kernel.org/r/20200104043110.707810-1-alexandre.belloni@bootlin.com Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2019-11-08rtc: Fix the AltCentury value on AMD/Hygon platformJinke Fan
When using following operations: date -s "21190910 19:20:00" hwclock -w to change date from 2019 to 2119 for test, it will fail on Hygon Dhyana and AMD Zen CPUs, while the same operations run ok on Intel i7 platform. MC146818 driver use function mc146818_set_time() to set register RTC_FREQ_SELECT(RTC_REG_A)'s bit4-bit6 field which means divider stage reset value on Intel platform to 0x7. While AMD/Hygon RTC_REG_A(0Ah)'s bit4 is defined as DV0 [Reference]: DV0 = 0 selects Bank 0, DV0 = 1 selects Bank 1. Bit5-bit6 is defined as reserved. DV0 is set to 1, it will select Bank 1, which will disable AltCentury register(0x32) access. As UEFI pass acpi_gbl_FADT.century 0x32 (AltCentury), the CMOS write will be failed on code: CMOS_WRITE(century, acpi_gbl_FADT.century). Correct RTC_REG_A bank select bit(DV0) to 0 on AMD/Hygon CPUs, it will enable AltCentury(0x32) register writing and finally setup century as expected. Test results on Intel i7, AMD EPYC(17h) and Hygon machine show that it works as expected. Compiling for sparc64 and alpha architectures are passed. Reference: https://www.amd.com/system/files/TechDocs/51192_Bolton_FCH_RRG.pdf section: 3.13 Real Time Clock (RTC) Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Jinke Fan <fanjinke@hygon.cn> Link: https://lore.kernel.org/r/20191105083943.115320-1-fanjinke@hygon.cn Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2019-05-21treewide: Add SPDX license identifier for missed filesThomas Gleixner
Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-01-22rtc: cmos: ignore bogus century byteEric Wong
Older versions of Libreboot and Coreboot had an invalid value (`3' in my case) in the century byte affecting the GM45 in the Thinkpad X200. Not everybody's updated their firmwares, and Linux <= 4.2 was able to read the RTC without problems, so workaround this by ignoring invalid values. Fixes: 3c217e51d8a272b9 ("rtc: cmos: century support") Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Sylvain Chouleur <sylvain.chouleur@intel.com> Cc: Patrick McDermott <patrick.mcdermott@libiquity.com> Cc: linux-rtc@vger.kernel.org Signed-off-by: Eric Wong <e@80x24.org> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2016-06-26rtc: move mc146818 helper functions out-of-lineArnd Bergmann
The mc146818_get_time/mc146818_set_time functions are rather large inline functions in a global header file and are used in several drivers and in x86 specific code. Here we move them into a separate .c file that is compiled whenever any of the users require it. This also lets us remove the linux/acpi.h header inclusion from mc146818rtc.h, which in turn avoids some warnings about duplicate definition of the TRUE/FALSE macros. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>