Commit 3c217e51 authored by Sylvain Chouleur's avatar Sylvain Chouleur Committed by Alexandre Belloni
Browse files

rtc: cmos: century support 



If century field is supported by the RTC CMOS device, then we should use
it and then do not consider years greater that 169 as an error.

For information, the year field of the rtc_time structure contains the
value to add to 1970 to obtain the current year.

This was a hack to be able to support years for 1970 to 2069.
This patch remains compatible with this implementation.

Signed-off-by: default avatarSylvain Chouleur <sylvain.chouleur@intel.com>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent 11f67a8b

include/asm-generic/rtc.h

+29 −0
Original line number Diff line number Diff line
@@ -16,6 +16,9 @@ 
#include <linux/rtc.h>

#include <linux/bcd.h>

#include <linux/delay.h>

#ifdef CONFIG_ACPI

#include <linux/acpi.h>

#endif



#define RTC_PIE 0x40		/* periodic interrupt enable */

#define RTC_AIE 0x20		/* alarm interrupt enable */
@@ -46,6 +49,7 @@ static inline unsigned int __get_rtc_time(struct rtc_time *time) 
{

	unsigned char ctrl;

	unsigned long flags;

	unsigned char century = 0;



#ifdef CONFIG_MACH_DECSTATION

	unsigned int real_year;
@@ -78,6 +82,11 @@ static inline unsigned int __get_rtc_time(struct rtc_time *time) 
	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);

	spin_unlock_irqrestore(&rtc_lock, flags);
@@ -90,12 +99,16 @@ static inline unsigned int __get_rtc_time(struct rtc_time *time) 
		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



	if (century)

		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;
@@ -122,6 +135,7 @@ static inline int __set_rtc_time(struct rtc_time *time) 
#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 */
@@ -150,6 +164,15 @@ static inline int __set_rtc_time(struct rtc_time *time) 
		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.

	 */
@@ -169,6 +192,7 @@ static inline int __set_rtc_time(struct rtc_time *time) 
		day = bin2bcd(day);

		mon = bin2bcd(mon);

		yrs = bin2bcd(yrs);

		century = bin2bcd(century);

	}



	save_control = CMOS_READ(RTC_CONTROL);
@@ -185,6 +209,11 @@ static inline int __set_rtc_time(struct rtc_time *time) 
	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);

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