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linux/drivers/rtc/rtc-mc146818-lib.c

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treewide: Add SPDX license identifier for missed files 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>
2019-05-19 15:08:55 +03:00
// SPDX-License-Identifier: GPL-2.0-only
rtc: move mc146818 helper functions out-of-line 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>
2016-06-01 17:46:23 +03:00
#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/mc146818rtc.h>
#ifdef CONFIG_ACPI
#include <linux/acpi.h>
#endif
unsigned int mc146818_get_time(struct rtc_time *time)
{
unsigned char ctrl;
unsigned long flags;
unsigned char century = 0;
rtc: mc146818: Prevent reading garbage The MC146818 driver is prone to read garbage from the RTC. There are several issues all related to the update cycle of the MC146818. The chip increments seconds obviously once per second and indicates that by a bit in a register. The bit goes high 244us before the actual update starts. During the update the readout of the time values is undefined. The code just checks whether the update in progress bit (UIP) is set before reading the clock. If it's set it waits arbitrary 20ms before retrying, which is ample because the maximum update time is ~2ms. But this check does not guarantee that the UIP bit goes high and the actual update happens during the readout. So the following can happen 0.997 UIP = False -> Interrupt/NMI/preemption 0.998 UIP -> True 0.999 Readout <- Undefined To prevent this rework the code so it checks UIP before and after the readout and if set after the readout try again. But that's not enough to cover the following: 0.997 UIP = False Readout seconds -> NMI (or vCPU scheduled out) 0.998 UIP -> True update completes UIP -> False 1.000 Readout minutes,.... UIP check succeeds That can make the readout wrong up to 59 seconds. To prevent this, read the seconds value before the first UIP check, validate it after checking UIP and after reading out the rest. It's amazing that the original i386 code had this actually correct and the generic implementation of the MC146818 driver got it wrong in 2002 and it stayed that way until today. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220541.594826678@linutronix.de
2020-12-07 00:46:14 +03:00
bool retry;
rtc: move mc146818 helper functions out-of-line 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>
2016-06-01 17:46:23 +03:00
#ifdef CONFIG_MACH_DECSTATION
unsigned int real_year;
#endif
rtc: mc146818: Prevent reading garbage The MC146818 driver is prone to read garbage from the RTC. There are several issues all related to the update cycle of the MC146818. The chip increments seconds obviously once per second and indicates that by a bit in a register. The bit goes high 244us before the actual update starts. During the update the readout of the time values is undefined. The code just checks whether the update in progress bit (UIP) is set before reading the clock. If it's set it waits arbitrary 20ms before retrying, which is ample because the maximum update time is ~2ms. But this check does not guarantee that the UIP bit goes high and the actual update happens during the readout. So the following can happen 0.997 UIP = False -> Interrupt/NMI/preemption 0.998 UIP -> True 0.999 Readout <- Undefined To prevent this rework the code so it checks UIP before and after the readout and if set after the readout try again. But that's not enough to cover the following: 0.997 UIP = False Readout seconds -> NMI (or vCPU scheduled out) 0.998 UIP -> True update completes UIP -> False 1.000 Readout minutes,.... UIP check succeeds That can make the readout wrong up to 59 seconds. To prevent this, read the seconds value before the first UIP check, validate it after checking UIP and after reading out the rest. It's amazing that the original i386 code had this actually correct and the generic implementation of the MC146818 driver got it wrong in 2002 and it stayed that way until today. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220541.594826678@linutronix.de
2020-12-07 00:46:14 +03:00
again:
spin_lock_irqsave(&rtc_lock, flags);
rtc: move mc146818 helper functions out-of-line 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>
2016-06-01 17:46:23 +03:00
/*
rtc: mc146818: Prevent reading garbage The MC146818 driver is prone to read garbage from the RTC. There are several issues all related to the update cycle of the MC146818. The chip increments seconds obviously once per second and indicates that by a bit in a register. The bit goes high 244us before the actual update starts. During the update the readout of the time values is undefined. The code just checks whether the update in progress bit (UIP) is set before reading the clock. If it's set it waits arbitrary 20ms before retrying, which is ample because the maximum update time is ~2ms. But this check does not guarantee that the UIP bit goes high and the actual update happens during the readout. So the following can happen 0.997 UIP = False -> Interrupt/NMI/preemption 0.998 UIP -> True 0.999 Readout <- Undefined To prevent this rework the code so it checks UIP before and after the readout and if set after the readout try again. But that's not enough to cover the following: 0.997 UIP = False Readout seconds -> NMI (or vCPU scheduled out) 0.998 UIP -> True update completes UIP -> False 1.000 Readout minutes,.... UIP check succeeds That can make the readout wrong up to 59 seconds. To prevent this, read the seconds value before the first UIP check, validate it after checking UIP and after reading out the rest. It's amazing that the original i386 code had this actually correct and the generic implementation of the MC146818 driver got it wrong in 2002 and it stayed that way until today. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220541.594826678@linutronix.de
2020-12-07 00:46:14 +03:00
* Check whether there is an update in progress during which the
* readout is unspecified. The maximum update time is ~2ms. Poll
* every msec for completion.
*
* Store the second value before checking UIP so a long lasting NMI
* which happens to hit after the UIP check cannot make an update
* cycle invisible.
rtc: move mc146818 helper functions out-of-line 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>
2016-06-01 17:46:23 +03:00
*/
rtc: mc146818: Prevent reading garbage The MC146818 driver is prone to read garbage from the RTC. There are several issues all related to the update cycle of the MC146818. The chip increments seconds obviously once per second and indicates that by a bit in a register. The bit goes high 244us before the actual update starts. During the update the readout of the time values is undefined. The code just checks whether the update in progress bit (UIP) is set before reading the clock. If it's set it waits arbitrary 20ms before retrying, which is ample because the maximum update time is ~2ms. But this check does not guarantee that the UIP bit goes high and the actual update happens during the readout. So the following can happen 0.997 UIP = False -> Interrupt/NMI/preemption 0.998 UIP -> True 0.999 Readout <- Undefined To prevent this rework the code so it checks UIP before and after the readout and if set after the readout try again. But that's not enough to cover the following: 0.997 UIP = False Readout seconds -> NMI (or vCPU scheduled out) 0.998 UIP -> True update completes UIP -> False 1.000 Readout minutes,.... UIP check succeeds That can make the readout wrong up to 59 seconds. To prevent this, read the seconds value before the first UIP check, validate it after checking UIP and after reading out the rest. It's amazing that the original i386 code had this actually correct and the generic implementation of the MC146818 driver got it wrong in 2002 and it stayed that way until today. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220541.594826678@linutronix.de
2020-12-07 00:46:14 +03:00
time->tm_sec = CMOS_READ(RTC_SECONDS);
if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP) {
spin_unlock_irqrestore(&rtc_lock, flags);
mdelay(1);
goto again;
}
/* Revalidate the above readout */
if (time->tm_sec != CMOS_READ(RTC_SECONDS)) {
spin_unlock_irqrestore(&rtc_lock, flags);
goto again;
}
rtc: move mc146818 helper functions out-of-line 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>
2016-06-01 17:46:23 +03:00
/*
* Only the values that we read from the RTC are set. We leave
* tm_wday, tm_yday and tm_isdst untouched. Even though the
* RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
* by the RTC when initially set to a non-zero value.
*/
time->tm_min = CMOS_READ(RTC_MINUTES);
time->tm_hour = CMOS_READ(RTC_HOURS);
time->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
time->tm_mon = CMOS_READ(RTC_MONTH);
time->tm_year = CMOS_READ(RTC_YEAR);
#ifdef CONFIG_MACH_DECSTATION
real_year = CMOS_READ(RTC_DEC_YEAR);
#endif
#ifdef CONFIG_ACPI
if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
acpi_gbl_FADT.century)
century = CMOS_READ(acpi_gbl_FADT.century);
#endif
ctrl = CMOS_READ(RTC_CONTROL);
rtc: mc146818: Prevent reading garbage The MC146818 driver is prone to read garbage from the RTC. There are several issues all related to the update cycle of the MC146818. The chip increments seconds obviously once per second and indicates that by a bit in a register. The bit goes high 244us before the actual update starts. During the update the readout of the time values is undefined. The code just checks whether the update in progress bit (UIP) is set before reading the clock. If it's set it waits arbitrary 20ms before retrying, which is ample because the maximum update time is ~2ms. But this check does not guarantee that the UIP bit goes high and the actual update happens during the readout. So the following can happen 0.997 UIP = False -> Interrupt/NMI/preemption 0.998 UIP -> True 0.999 Readout <- Undefined To prevent this rework the code so it checks UIP before and after the readout and if set after the readout try again. But that's not enough to cover the following: 0.997 UIP = False Readout seconds -> NMI (or vCPU scheduled out) 0.998 UIP -> True update completes UIP -> False 1.000 Readout minutes,.... UIP check succeeds That can make the readout wrong up to 59 seconds. To prevent this, read the seconds value before the first UIP check, validate it after checking UIP and after reading out the rest. It's amazing that the original i386 code had this actually correct and the generic implementation of the MC146818 driver got it wrong in 2002 and it stayed that way until today. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220541.594826678@linutronix.de
2020-12-07 00:46:14 +03:00
/*
* Check for the UIP bit again. If it is set now then
* the above values may contain garbage.
*/
retry = CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP;
/*
* A NMI might have interrupted the above sequence so check whether
* the seconds value has changed which indicates that the NMI took
* longer than the UIP bit was set. Unlikely, but possible and
* there is also virt...
*/
retry |= time->tm_sec != CMOS_READ(RTC_SECONDS);
rtc: move mc146818 helper functions out-of-line 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>
2016-06-01 17:46:23 +03:00
spin_unlock_irqrestore(&rtc_lock, flags);
rtc: mc146818: Prevent reading garbage The MC146818 driver is prone to read garbage from the RTC. There are several issues all related to the update cycle of the MC146818. The chip increments seconds obviously once per second and indicates that by a bit in a register. The bit goes high 244us before the actual update starts. During the update the readout of the time values is undefined. The code just checks whether the update in progress bit (UIP) is set before reading the clock. If it's set it waits arbitrary 20ms before retrying, which is ample because the maximum update time is ~2ms. But this check does not guarantee that the UIP bit goes high and the actual update happens during the readout. So the following can happen 0.997 UIP = False -> Interrupt/NMI/preemption 0.998 UIP -> True 0.999 Readout <- Undefined To prevent this rework the code so it checks UIP before and after the readout and if set after the readout try again. But that's not enough to cover the following: 0.997 UIP = False Readout seconds -> NMI (or vCPU scheduled out) 0.998 UIP -> True update completes UIP -> False 1.000 Readout minutes,.... UIP check succeeds That can make the readout wrong up to 59 seconds. To prevent this, read the seconds value before the first UIP check, validate it after checking UIP and after reading out the rest. It's amazing that the original i386 code had this actually correct and the generic implementation of the MC146818 driver got it wrong in 2002 and it stayed that way until today. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220541.594826678@linutronix.de
2020-12-07 00:46:14 +03:00
if (retry)
goto again;
rtc: move mc146818 helper functions out-of-line 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>
2016-06-01 17:46:23 +03:00
if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
{
time->tm_sec = bcd2bin(time->tm_sec);
time->tm_min = bcd2bin(time->tm_min);
time->tm_hour = bcd2bin(time->tm_hour);
time->tm_mday = bcd2bin(time->tm_mday);
time->tm_mon = bcd2bin(time->tm_mon);
time->tm_year = bcd2bin(time->tm_year);
century = bcd2bin(century);
}
#ifdef CONFIG_MACH_DECSTATION
time->tm_year += real_year - 72;
#endif
rtc: cmos: ignore bogus century byte 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>
2019-01-06 11:21:03 +03:00
if (century > 20)
rtc: move mc146818 helper functions out-of-line 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>
2016-06-01 17:46:23 +03:00
time->tm_year += (century - 19) * 100;
/*
* Account for differences between how the RTC uses the values
* and how they are defined in a struct rtc_time;
*/
if (time->tm_year <= 69)
time->tm_year += 100;
time->tm_mon--;
return RTC_24H;
}
EXPORT_SYMBOL_GPL(mc146818_get_time);
/* Set the current date and time in the real time clock. */
int mc146818_set_time(struct rtc_time *time)
{
unsigned long flags;
unsigned char mon, day, hrs, min, sec;
unsigned char save_control, save_freq_select;
unsigned int yrs;
#ifdef CONFIG_MACH_DECSTATION
unsigned int real_yrs, leap_yr;
#endif
unsigned char century = 0;
yrs = time->tm_year;
mon = time->tm_mon + 1; /* tm_mon starts at zero */
day = time->tm_mday;
hrs = time->tm_hour;
min = time->tm_min;
sec = time->tm_sec;
if (yrs > 255) /* They are unsigned */
return -EINVAL;
#ifdef CONFIG_MACH_DECSTATION
real_yrs = yrs;
leap_yr = ((!((yrs + 1900) % 4) && ((yrs + 1900) % 100)) ||
!((yrs + 1900) % 400));
yrs = 72;
/*
* We want to keep the year set to 73 until March
* for non-leap years, so that Feb, 29th is handled
* correctly.
*/
if (!leap_yr && mon < 3) {
real_yrs--;
yrs = 73;
}
#endif
#ifdef CONFIG_ACPI
if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
acpi_gbl_FADT.century) {
century = (yrs + 1900) / 100;
yrs %= 100;
}
#endif
/* These limits and adjustments are independent of
* whether the chip is in binary mode or not.
*/
rtc: mc146818: Reduce spinlock section in mc146818_set_time() No need to hold the lock and disable interrupts for doing math. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220541.709243630@linutronix.de
2020-12-07 00:46:15 +03:00
if (yrs > 169)
rtc: move mc146818 helper functions out-of-line 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>
2016-06-01 17:46:23 +03:00
return -EINVAL;
if (yrs >= 100)
yrs -= 100;
if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
|| RTC_ALWAYS_BCD) {
sec = bin2bcd(sec);
min = bin2bcd(min);
hrs = bin2bcd(hrs);
day = bin2bcd(day);
mon = bin2bcd(mon);
yrs = bin2bcd(yrs);
century = bin2bcd(century);
}
rtc: mc146818: Reduce spinlock section in mc146818_set_time() No need to hold the lock and disable interrupts for doing math. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220541.709243630@linutronix.de
2020-12-07 00:46:15 +03:00
spin_lock_irqsave(&rtc_lock, flags);
rtc: move mc146818 helper functions out-of-line 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>
2016-06-01 17:46:23 +03:00
save_control = CMOS_READ(RTC_CONTROL);
CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
rtc: cmos: Revert "rtc: Fix the AltCentury value on AMD/Hygon platform" 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>
2020-01-04 07:31:10 +03:00
CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
rtc: move mc146818 helper functions out-of-line 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>
2016-06-01 17:46:23 +03:00
#ifdef CONFIG_MACH_DECSTATION
CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
#endif
CMOS_WRITE(yrs, RTC_YEAR);
CMOS_WRITE(mon, RTC_MONTH);
CMOS_WRITE(day, RTC_DAY_OF_MONTH);
CMOS_WRITE(hrs, RTC_HOURS);
CMOS_WRITE(min, RTC_MINUTES);
CMOS_WRITE(sec, RTC_SECONDS);
#ifdef CONFIG_ACPI
if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
acpi_gbl_FADT.century)
CMOS_WRITE(century, acpi_gbl_FADT.century);
#endif
CMOS_WRITE(save_control, RTC_CONTROL);
CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
spin_unlock_irqrestore(&rtc_lock, flags);
return 0;
}
EXPORT_SYMBOL_GPL(mc146818_set_time);
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