diff options
Diffstat (limited to 'arch/x86/kernel/rtc.c')
| -rw-r--r-- | arch/x86/kernel/rtc.c | 96 |
1 files changed, 63 insertions, 33 deletions
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c index 45bf54d9f4c..d040840ff1b 100644 --- a/arch/x86/kernel/rtc.c +++ b/arch/x86/kernel/rtc.c @@ -1,11 +1,32 @@ /* * RTC related functions */ +#include <linux/acpi.h> #include <linux/bcd.h> #include <linux/mc146818rtc.h> #include <asm/time.h> +#ifdef CONFIG_X86_32 +# define CMOS_YEARS_OFFS 1900 +/* + * This is a special lock that is owned by the CPU and holds the index + * register we are working with. It is required for NMI access to the + * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details. + */ +volatile unsigned long cmos_lock = 0; +EXPORT_SYMBOL(cmos_lock); +#else +/* + * x86-64 systems only exists since 2002. + * This will work up to Dec 31, 2100 + */ +# define CMOS_YEARS_OFFS 2000 +#endif + +DEFINE_SPINLOCK(rtc_lock); +EXPORT_SYMBOL(rtc_lock); + /* * In order to set the CMOS clock precisely, set_rtc_mmss has to be * called 500 ms after the second nowtime has started, because when @@ -22,10 +43,12 @@ int mach_set_rtc_mmss(unsigned long nowtime) int real_seconds, real_minutes, cmos_minutes; unsigned char save_control, save_freq_select; - save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */ + /* tell the clock it's being set */ + save_control = CMOS_READ(RTC_CONTROL); CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); - save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */ + /* stop and reset prescaler */ + save_freq_select = CMOS_READ(RTC_FREQ_SELECT); CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); cmos_minutes = CMOS_READ(RTC_MINUTES); @@ -40,8 +63,9 @@ int mach_set_rtc_mmss(unsigned long nowtime) */ real_seconds = nowtime % 60; real_minutes = nowtime / 60; + /* correct for half hour time zone */ if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1) - real_minutes += 30; /* correct for half hour time zone */ + real_minutes += 30; real_minutes %= 60; if (abs(real_minutes - cmos_minutes) < 30) { @@ -73,18 +97,32 @@ int mach_set_rtc_mmss(unsigned long nowtime) unsigned long mach_get_cmos_time(void) { - unsigned int year, mon, day, hour, min, sec; - - do { - sec = CMOS_READ(RTC_SECONDS); - min = CMOS_READ(RTC_MINUTES); - hour = CMOS_READ(RTC_HOURS); - day = CMOS_READ(RTC_DAY_OF_MONTH); - mon = CMOS_READ(RTC_MONTH); - year = CMOS_READ(RTC_YEAR); - } while (sec != CMOS_READ(RTC_SECONDS)); - - if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { + unsigned int year, mon, day, hour, min, sec, century = 0; + + /* + * If UIP is clear, then we have >= 244 microseconds before + * RTC registers will be updated. Spec sheet says that this + * is the reliable way to read RTC - registers. If UIP is set + * then the register access might be invalid. + */ + while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)) + cpu_relax(); + + sec = CMOS_READ(RTC_SECONDS); + min = CMOS_READ(RTC_MINUTES); + hour = CMOS_READ(RTC_HOURS); + day = CMOS_READ(RTC_DAY_OF_MONTH); + mon = CMOS_READ(RTC_MONTH); + year = CMOS_READ(RTC_YEAR); + +#if defined(CONFIG_ACPI) && defined(CONFIG_X86_64) + /* CHECKME: Is this really 64bit only ??? */ + if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID && + acpi_gbl_FADT.century) + century = CMOS_READ(acpi_gbl_FADT.century); +#endif + + if (RTC_ALWAYS_BCD || !(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)) { BCD_TO_BIN(sec); BCD_TO_BIN(min); BCD_TO_BIN(hour); @@ -93,24 +131,19 @@ unsigned long mach_get_cmos_time(void) BCD_TO_BIN(year); } - year += 1900; - if (year < 1970) - year += 100; + if (century) { + BCD_TO_BIN(century); + year += century * 100; + printk(KERN_INFO "Extended CMOS year: %d\n", century * 100); + } else { + year += CMOS_YEARS_OFFS; + if (year < 1970) + year += 100; + } return mktime(year, mon, day, hour, min, sec); } -DEFINE_SPINLOCK(rtc_lock); -EXPORT_SYMBOL(rtc_lock); - -/* - * This is a special lock that is owned by the CPU and holds the index - * register we are working with. It is required for NMI access to the - * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details. - */ -volatile unsigned long cmos_lock = 0; -EXPORT_SYMBOL(cmos_lock); - /* Routines for accessing the CMOS RAM/RTC. */ unsigned char rtc_cmos_read(unsigned char addr) { @@ -138,8 +171,6 @@ static int set_rtc_mmss(unsigned long nowtime) int retval; unsigned long flags; - /* gets recalled with irq locally disabled */ - /* XXX - does irqsave resolve this? -johnstul */ spin_lock_irqsave(&rtc_lock, flags); retval = set_wallclock(nowtime); spin_unlock_irqrestore(&rtc_lock, flags); @@ -150,8 +181,7 @@ static int set_rtc_mmss(unsigned long nowtime) /* not static: needed by APM */ unsigned long read_persistent_clock(void) { - unsigned long retval; - unsigned long flags; + unsigned long retval, flags; spin_lock_irqsave(&rtc_lock, flags); retval = get_wallclock(); |