arch/x86_64/kernel/time.c - LeafOS-Devices/android_kernel_realme_mt6785 - Gitiles

 /*
  *  linux/arch/x86-64/kernel/time.c
  *
  *  "High Precision Event Timer" based timekeeping.
  *
  *  Copyright (c) 1991,1992,1995  Linus Torvalds
  *  Copyright (c) 1994  Alan Modra
  *  Copyright (c) 1995  Markus Kuhn
  *  Copyright (c) 1996  Ingo Molnar
  *  Copyright (c) 1998  Andrea Arcangeli
  *  Copyright (c) 2002,2006  Vojtech Pavlik
  *  Copyright (c) 2003  Andi Kleen
  *  RTC support code taken from arch/i386/kernel/timers/time_hpet.c
  */

 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>
 #include <linux/mc146818rtc.h>
 #include <linux/time.h>
 #include <linux/ioport.h>
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/sysdev.h>
 #include <linux/bcd.h>
 #include <linux/notifier.h>
 #include <linux/cpu.h>
 #include <linux/kallsyms.h>
 #include <linux/acpi.h>
 #ifdef CONFIG_ACPI
 #include <acpi/achware.h>	/* for PM timer frequency */
 #include <acpi/acpi_bus.h>
 #endif
 #include <asm/8253pit.h>
 #include <asm/pgtable.h>
 #include <asm/vsyscall.h>
 #include <asm/timex.h>
 #include <asm/proto.h>
 #include <asm/hpet.h>
 #include <asm/sections.h>
 #include <linux/hpet.h>
 #include <asm/apic.h>
 #include <asm/hpet.h>
 #include <asm/mpspec.h>
 #include <asm/nmi.h>

 static char *timename = NULL;

 DEFINE_SPINLOCK(rtc_lock);
 EXPORT_SYMBOL(rtc_lock);
 DEFINE_SPINLOCK(i8253_lock);

 volatile unsigned long __jiffies __section_jiffies = INITIAL_JIFFIES;

 unsigned long profile_pc(struct pt_regs *regs)
 {
 	unsigned long pc = instruction_pointer(regs);

 	/* Assume the lock function has either no stack frame or a copy
 	   of eflags from PUSHF
 	   Eflags always has bits 22 and up cleared unlike kernel addresses. */
 	if (!user_mode(regs) && in_lock_functions(pc)) {
 		unsigned long *sp = (unsigned long *)regs->rsp;
 		if (sp[0] >> 22)
 			return sp[0];
 		if (sp[1] >> 22)
 			return sp[1];
 	}
 	return pc;
 }
 EXPORT_SYMBOL(profile_pc);

 /*
  * 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 nowtime is written
  * into the registers of the CMOS clock, it will jump to the next second
  * precisely 500 ms later. Check the Motorola MC146818A or Dallas DS12887 data
  * sheet for details.
  */

 static void set_rtc_mmss(unsigned long nowtime)
 {
 	int real_seconds, real_minutes, cmos_minutes;
 	unsigned char control, freq_select;

 /*
  * IRQs are disabled when we're called from the timer interrupt,
  * no need for spin_lock_irqsave()
  */

 	spin_lock(&rtc_lock);

 /*
  * Tell the clock it's being set and stop it.
  */

 	control = CMOS_READ(RTC_CONTROL);
 	CMOS_WRITE(control | RTC_SET, RTC_CONTROL);

 	freq_select = CMOS_READ(RTC_FREQ_SELECT);
 	CMOS_WRITE(freq_select | RTC_DIV_RESET2, RTC_FREQ_SELECT);

 	cmos_minutes = CMOS_READ(RTC_MINUTES);
 		BCD_TO_BIN(cmos_minutes);

 /*
  * since we're only adjusting minutes and seconds, don't interfere with hour
  * overflow. This avoids messing with unknown time zones but requires your RTC
  * not to be off by more than 15 minutes. Since we're calling it only when
  * our clock is externally synchronized using NTP, this shouldn't be a problem.
  */

 	real_seconds = nowtime % 60;
 	real_minutes = nowtime / 60;
 	if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
 		real_minutes += 30;		/* correct for half hour time zone */
 	real_minutes %= 60;

 	if (abs(real_minutes - cmos_minutes) >= 30) {
 		printk(KERN_WARNING "time.c: can't update CMOS clock "
 		       "from %d to %d\n", cmos_minutes, real_minutes);
 	} else {
 		BIN_TO_BCD(real_seconds);
 		BIN_TO_BCD(real_minutes);
 		CMOS_WRITE(real_seconds, RTC_SECONDS);
 		CMOS_WRITE(real_minutes, RTC_MINUTES);
 	}

 /*
  * The following flags have to be released exactly in this order, otherwise the
  * DS12887 (popular MC146818A clone with integrated battery and quartz) will
  * not reset the oscillator and will not update precisely 500 ms later. You
  * won't find this mentioned in the Dallas Semiconductor data sheets, but who
  * believes data sheets anyway ... -- Markus Kuhn
  */

 	CMOS_WRITE(control, RTC_CONTROL);
 	CMOS_WRITE(freq_select, RTC_FREQ_SELECT);

 	spin_unlock(&rtc_lock);
 }


 void main_timer_handler(void)
 {
 	static unsigned long rtc_update = 0;
 /*
  * Here we are in the timer irq handler. We have irqs locally disabled (so we
  * don't need spin_lock_irqsave()) but we don't know if the timer_bh is running
  * on the other CPU, so we need a lock. We also need to lock the vsyscall
  * variables, because both do_timer() and us change them -arca+vojtech
  */

 	write_seqlock(&xtime_lock);

 /*
  * Do the timer stuff.
  */

 	do_timer(1);
 #ifndef CONFIG_SMP
 	update_process_times(user_mode(get_irq_regs()));
 #endif

 /*
  * In the SMP case we use the local APIC timer interrupt to do the profiling,
  * except when we simulate SMP mode on a uniprocessor system, in that case we
  * have to call the local interrupt handler.
  */

 	if (!using_apic_timer)
 		smp_local_timer_interrupt();

 /*
  * If we have an externally synchronized Linux clock, then update CMOS clock
  * accordingly every ~11 minutes. set_rtc_mmss() will be called in the jiffy
  * closest to exactly 500 ms before the next second. If the update fails, we
  * don't care, as it'll be updated on the next turn, and the problem (time way
  * off) isn't likely to go away much sooner anyway.
  */

 	if (ntp_synced() && xtime.tv_sec > rtc_update &&
 		abs(xtime.tv_nsec - 500000000) <= tick_nsec / 2) {
 		set_rtc_mmss(xtime.tv_sec);
 		rtc_update = xtime.tv_sec + 660;
 	}

 	write_sequnlock(&xtime_lock);
 }

 static irqreturn_t timer_interrupt(int irq, void *dev_id)
 {
 	if (apic_runs_main_timer > 1)
 		return IRQ_HANDLED;
 	main_timer_handler();
 	if (using_apic_timer)
 		smp_send_timer_broadcast_ipi();
 	return IRQ_HANDLED;
 }

 static unsigned long get_cmos_time(void)
 {
 	unsigned int year, mon, day, hour, min, sec;
 	unsigned long flags;
 	unsigned century = 0;

 	spin_lock_irqsave(&rtc_lock, flags);

 	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);
 #ifdef CONFIG_ACPI
 		if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
 					acpi_gbl_FADT.century)
 			century = CMOS_READ(acpi_gbl_FADT.century);
 #endif
 	} while (sec != CMOS_READ(RTC_SECONDS));

 	spin_unlock_irqrestore(&rtc_lock, flags);

 	/*
 	 * We know that x86-64 always uses BCD format, no need to check the
 	 * config register.
  	 */

 	BCD_TO_BIN(sec);
 	BCD_TO_BIN(min);
 	BCD_TO_BIN(hour);
 	BCD_TO_BIN(day);
 	BCD_TO_BIN(mon);
 	BCD_TO_BIN(year);

 	if (century) {
 		BCD_TO_BIN(century);
 		year += century * 100;
 		printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
 	} else {
 		/*
 		 * x86-64 systems only exists since 2002.
 		 * This will work up to Dec 31, 2100
 	 	 */
 		year += 2000;
 	}

 	return mktime(year, mon, day, hour, min, sec);
 }

 /* calibrate_cpu is used on systems with fixed rate TSCs to determine
  * processor frequency */
 #define TICK_COUNT 100000000
 static unsigned int __init tsc_calibrate_cpu_khz(void)
 {
        int tsc_start, tsc_now;
        int i, no_ctr_free;
        unsigned long evntsel3 = 0, pmc3 = 0, pmc_now = 0;
        unsigned long flags;

        for (i = 0; i < 4; i++)
                if (avail_to_resrv_perfctr_nmi_bit(i))
                        break;
        no_ctr_free = (i == 4);
        if (no_ctr_free) {
                i = 3;
                rdmsrl(MSR_K7_EVNTSEL3, evntsel3);
                wrmsrl(MSR_K7_EVNTSEL3, 0);
                rdmsrl(MSR_K7_PERFCTR3, pmc3);
        } else {
                reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i);
                reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
        }
        local_irq_save(flags);
        /* start meauring cycles, incrementing from 0 */
        wrmsrl(MSR_K7_PERFCTR0 + i, 0);
        wrmsrl(MSR_K7_EVNTSEL0 + i, 1 << 22 | 3 << 16 | 0x76);
        rdtscl(tsc_start);
        do {
                rdmsrl(MSR_K7_PERFCTR0 + i, pmc_now);
                tsc_now = get_cycles_sync();
        } while ((tsc_now - tsc_start) < TICK_COUNT);

        local_irq_restore(flags);
        if (no_ctr_free) {
                wrmsrl(MSR_K7_EVNTSEL3, 0);
                wrmsrl(MSR_K7_PERFCTR3, pmc3);
                wrmsrl(MSR_K7_EVNTSEL3, evntsel3);
        } else {
                release_perfctr_nmi(MSR_K7_PERFCTR0 + i);
                release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
        }

        return pmc_now * tsc_khz / (tsc_now - tsc_start);
 }

 /*
  * pit_calibrate_tsc() uses the speaker output (channel 2) of
  * the PIT. This is better than using the timer interrupt output,
  * because we can read the value of the speaker with just one inb(),
  * where we need three i/o operations for the interrupt channel.
  * We count how many ticks the TSC does in 50 ms.
  */

 static unsigned int __init pit_calibrate_tsc(void)
 {
 	unsigned long start, end;
 	unsigned long flags;

 	spin_lock_irqsave(&i8253_lock, flags);

 	outb((inb(0x61) & ~0x02) | 0x01, 0x61);

 	outb(0xb0, 0x43);
 	outb((PIT_TICK_RATE / (1000 / 50)) & 0xff, 0x42);
 	outb((PIT_TICK_RATE / (1000 / 50)) >> 8, 0x42);
 	start = get_cycles_sync();
 	while ((inb(0x61) & 0x20) == 0);
 	end = get_cycles_sync();

 	spin_unlock_irqrestore(&i8253_lock, flags);

 	return (end - start) / 50;
 }

 #define PIT_MODE 0x43
 #define PIT_CH0  0x40

 static void __pit_init(int val, u8 mode)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&i8253_lock, flags);
 	outb_p(mode, PIT_MODE);
 	outb_p(val & 0xff, PIT_CH0);	/* LSB */
 	outb_p(val >> 8, PIT_CH0);	/* MSB */
 	spin_unlock_irqrestore(&i8253_lock, flags);
 }

 void __init pit_init(void)
 {
 	__pit_init(LATCH, 0x34); /* binary, mode 2, LSB/MSB, ch 0 */
 }

 void pit_stop_interrupt(void)
 {
 	__pit_init(0, 0x30); /* mode 0 */
 }

 void stop_timer_interrupt(void)
 {
 	char *name;
 	if (hpet_address) {
 		name = "HPET";
 		hpet_timer_stop_set_go(0);
 	} else {
 		name = "PIT";
 		pit_stop_interrupt();
 	}
 	printk(KERN_INFO "timer: %s interrupt stopped.\n", name);
 }

 static struct irqaction irq0 = {
 	timer_interrupt, IRQF_DISABLED, CPU_MASK_NONE, "timer", NULL, NULL
 };

 void __init time_init(void)
 {
 	if (nohpet)
 		hpet_address = 0;
 	xtime.tv_sec = get_cmos_time();
 	xtime.tv_nsec = 0;

 	set_normalized_timespec(&wall_to_monotonic,
 	                        -xtime.tv_sec, -xtime.tv_nsec);

 	if (hpet_arch_init())
 		hpet_address = 0;

 	if (hpet_use_timer) {
 		/* set tick_nsec to use the proper rate for HPET */
 	  	tick_nsec = TICK_NSEC_HPET;
 		tsc_khz = hpet_calibrate_tsc();
 		timename = "HPET";
 	} else {
 		pit_init();
 		tsc_khz = pit_calibrate_tsc();
 		timename = "PIT";
 	}

 	cpu_khz = tsc_khz;
 	if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) &&
 		boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
 		boot_cpu_data.x86 == 16)
 		cpu_khz = tsc_calibrate_cpu_khz();

 	if (unsynchronized_tsc())
 		mark_tsc_unstable("TSCs unsynchronized");

 	if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
 		vgetcpu_mode = VGETCPU_RDTSCP;
 	else
 		vgetcpu_mode = VGETCPU_LSL;

 	set_cyc2ns_scale(tsc_khz);
 	printk(KERN_INFO "time.c: Detected %d.%03d MHz processor.\n",
 		cpu_khz / 1000, cpu_khz % 1000);
 	init_tsc_clocksource();

 	setup_irq(0, &irq0);
 }


 static long clock_cmos_diff;
 static unsigned long sleep_start;

 /*
  * sysfs support for the timer.
  */

 static int timer_suspend(struct sys_device *dev, pm_message_t state)
 {
 	/*
 	 * Estimate time zone so that set_time can update the clock
 	 */
 	long cmos_time =  get_cmos_time();

 	clock_cmos_diff = -cmos_time;
 	clock_cmos_diff += get_seconds();
 	sleep_start = cmos_time;
 	return 0;
 }

 static int timer_resume(struct sys_device *dev)
 {
 	unsigned long flags;
 	unsigned long sec;
 	unsigned long ctime = get_cmos_time();
 	long sleep_length = (ctime - sleep_start) * HZ;

 	if (sleep_length < 0) {
 		printk(KERN_WARNING "Time skew detected in timer resume!\n");
 		/* The time after the resume must not be earlier than the time
 		 * before the suspend or some nasty things will happen
 		 */
 		sleep_length = 0;
 		ctime = sleep_start;
 	}
 	if (hpet_address)
 		hpet_reenable();
 	else
 		i8254_timer_resume();

 	sec = ctime + clock_cmos_diff;
 	write_seqlock_irqsave(&xtime_lock,flags);
 	xtime.tv_sec = sec;
 	xtime.tv_nsec = 0;
 	jiffies += sleep_length;
 	write_sequnlock_irqrestore(&xtime_lock,flags);
 	touch_softlockup_watchdog();
 	return 0;
 }

 static struct sysdev_class timer_sysclass = {
 	.resume = timer_resume,
 	.suspend = timer_suspend,
 	set_kset_name("timer"),
 };

 /* XXX this sysfs stuff should probably go elsewhere later -john */
 static struct sys_device device_timer = {
 	.id	= 0,
 	.cls	= &timer_sysclass,
 };

 static int time_init_device(void)
 {
 	int error = sysdev_class_register(&timer_sysclass);
 	if (!error)
 		error = sysdev_register(&device_timer);
 	return error;
 }

 device_initcall(time_init_device);
	/*
	* linux/arch/x86-64/kernel/time.c
	*
	* "High Precision Event Timer" based timekeeping.
	*
	* Copyright (c) 1991,1992,1995 Linus Torvalds
	* Copyright (c) 1994 Alan Modra
	* Copyright (c) 1995 Markus Kuhn
	* Copyright (c) 1996 Ingo Molnar
	* Copyright (c) 1998 Andrea Arcangeli
	* Copyright (c) 2002,2006 Vojtech Pavlik
	* Copyright (c) 2003 Andi Kleen
	* RTC support code taken from arch/i386/kernel/timers/time_hpet.c
	*/

	#include <linux/kernel.h>
	#include <linux/sched.h>
	#include <linux/interrupt.h>
	#include <linux/init.h>
	#include <linux/mc146818rtc.h>
	#include <linux/time.h>
	#include <linux/ioport.h>
	#include <linux/module.h>
	#include <linux/device.h>
	#include <linux/sysdev.h>
	#include <linux/bcd.h>
	#include <linux/notifier.h>
	#include <linux/cpu.h>
	#include <linux/kallsyms.h>
	#include <linux/acpi.h>
	#ifdef CONFIG_ACPI
	#include <acpi/achware.h> /* for PM timer frequency */
	#include <acpi/acpi_bus.h>
	#endif
	#include <asm/8253pit.h>
	#include <asm/pgtable.h>
	#include <asm/vsyscall.h>
	#include <asm/timex.h>
	#include <asm/proto.h>
	#include <asm/hpet.h>
	#include <asm/sections.h>
	#include <linux/hpet.h>
	#include <asm/apic.h>
	#include <asm/hpet.h>
	#include <asm/mpspec.h>
	#include <asm/nmi.h>

	static char *timename = NULL;

	DEFINE_SPINLOCK(rtc_lock);
	EXPORT_SYMBOL(rtc_lock);
	DEFINE_SPINLOCK(i8253_lock);

	volatile unsigned long __jiffies __section_jiffies = INITIAL_JIFFIES;

	unsigned long profile_pc(struct pt_regs *regs)
	{
	unsigned long pc = instruction_pointer(regs);

	/* Assume the lock function has either no stack frame or a copy
	of eflags from PUSHF
	Eflags always has bits 22 and up cleared unlike kernel addresses. */
	if (!user_mode(regs) && in_lock_functions(pc)) {
	unsigned long sp = (unsigned long )regs->rsp;
	if (sp[0] >> 22)
	return sp[0];
	if (sp[1] >> 22)
	return sp[1];
	}
	return pc;
	}
	EXPORT_SYMBOL(profile_pc);

	/*
	* 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 nowtime is written
	* into the registers of the CMOS clock, it will jump to the next second
	* precisely 500 ms later. Check the Motorola MC146818A or Dallas DS12887 data
	* sheet for details.
	*/

	static void set_rtc_mmss(unsigned long nowtime)
	{
	int real_seconds, real_minutes, cmos_minutes;
	unsigned char control, freq_select;

	/*
	* IRQs are disabled when we're called from the timer interrupt,
	* no need for spin_lock_irqsave()
	*/

	spin_lock(&rtc_lock);

	/*
	* Tell the clock it's being set and stop it.
	*/

	control = CMOS_READ(RTC_CONTROL);
	CMOS_WRITE(control \| RTC_SET, RTC_CONTROL);

	freq_select = CMOS_READ(RTC_FREQ_SELECT);
	CMOS_WRITE(freq_select \| RTC_DIV_RESET2, RTC_FREQ_SELECT);

	cmos_minutes = CMOS_READ(RTC_MINUTES);
	BCD_TO_BIN(cmos_minutes);

	/*
	* since we're only adjusting minutes and seconds, don't interfere with hour
	* overflow. This avoids messing with unknown time zones but requires your RTC
	* not to be off by more than 15 minutes. Since we're calling it only when
	* our clock is externally synchronized using NTP, this shouldn't be a problem.
	*/

	real_seconds = nowtime % 60;
	real_minutes = nowtime / 60;
	if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
	real_minutes += 30; /* correct for half hour time zone */
	real_minutes %= 60;

	if (abs(real_minutes - cmos_minutes) >= 30) {
	printk(KERN_WARNING "time.c: can't update CMOS clock "
	"from %d to %d\n", cmos_minutes, real_minutes);
	} else {
	BIN_TO_BCD(real_seconds);
	BIN_TO_BCD(real_minutes);
	CMOS_WRITE(real_seconds, RTC_SECONDS);
	CMOS_WRITE(real_minutes, RTC_MINUTES);
	}

	/*
	* The following flags have to be released exactly in this order, otherwise the
	* DS12887 (popular MC146818A clone with integrated battery and quartz) will
	* not reset the oscillator and will not update precisely 500 ms later. You
	* won't find this mentioned in the Dallas Semiconductor data sheets, but who
	* believes data sheets anyway ... -- Markus Kuhn
	*/

	CMOS_WRITE(control, RTC_CONTROL);
	CMOS_WRITE(freq_select, RTC_FREQ_SELECT);

	spin_unlock(&rtc_lock);
	}


	void main_timer_handler(void)
	{
	static unsigned long rtc_update = 0;
	/*
	* Here we are in the timer irq handler. We have irqs locally disabled (so we
	* don't need spin_lock_irqsave()) but we don't know if the timer_bh is running
	* on the other CPU, so we need a lock. We also need to lock the vsyscall
	* variables, because both do_timer() and us change them -arca+vojtech
	*/

	write_seqlock(&xtime_lock);

	/*
	* Do the timer stuff.
	*/

	do_timer(1);
	#ifndef CONFIG_SMP
	update_process_times(user_mode(get_irq_regs()));
	#endif

	/*
	* In the SMP case we use the local APIC timer interrupt to do the profiling,
	* except when we simulate SMP mode on a uniprocessor system, in that case we
	* have to call the local interrupt handler.
	*/

	if (!using_apic_timer)
	smp_local_timer_interrupt();

	/*
	* If we have an externally synchronized Linux clock, then update CMOS clock
	* accordingly every ~11 minutes. set_rtc_mmss() will be called in the jiffy
	* closest to exactly 500 ms before the next second. If the update fails, we
	* don't care, as it'll be updated on the next turn, and the problem (time way
	* off) isn't likely to go away much sooner anyway.
	*/

	if (ntp_synced() && xtime.tv_sec > rtc_update &&
	abs(xtime.tv_nsec - 500000000) <= tick_nsec / 2) {
	set_rtc_mmss(xtime.tv_sec);
	rtc_update = xtime.tv_sec + 660;
	}

	write_sequnlock(&xtime_lock);
	}

	static irqreturn_t timer_interrupt(int irq, void *dev_id)
	{
	if (apic_runs_main_timer > 1)
	return IRQ_HANDLED;
	main_timer_handler();
	if (using_apic_timer)
	smp_send_timer_broadcast_ipi();
	return IRQ_HANDLED;
	}

	static unsigned long get_cmos_time(void)
	{
	unsigned int year, mon, day, hour, min, sec;
	unsigned long flags;
	unsigned century = 0;

	spin_lock_irqsave(&rtc_lock, flags);

	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);
	#ifdef CONFIG_ACPI
	if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
	acpi_gbl_FADT.century)
	century = CMOS_READ(acpi_gbl_FADT.century);
	#endif
	} while (sec != CMOS_READ(RTC_SECONDS));

	spin_unlock_irqrestore(&rtc_lock, flags);

	/*
	* We know that x86-64 always uses BCD format, no need to check the
	* config register.
	*/

	BCD_TO_BIN(sec);
	BCD_TO_BIN(min);
	BCD_TO_BIN(hour);
	BCD_TO_BIN(day);
	BCD_TO_BIN(mon);
	BCD_TO_BIN(year);

	if (century) {
	BCD_TO_BIN(century);
	year += century * 100;
	printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
	} else {
	/*
	* x86-64 systems only exists since 2002.
	* This will work up to Dec 31, 2100
	*/
	year += 2000;
	}

	return mktime(year, mon, day, hour, min, sec);
	}

	/* calibrate_cpu is used on systems with fixed rate TSCs to determine
	* processor frequency */
	#define TICK_COUNT 100000000
	static unsigned int __init tsc_calibrate_cpu_khz(void)
	{
	int tsc_start, tsc_now;
	int i, no_ctr_free;
	unsigned long evntsel3 = 0, pmc3 = 0, pmc_now = 0;
	unsigned long flags;

	for (i = 0; i < 4; i++)
	if (avail_to_resrv_perfctr_nmi_bit(i))
	break;
	no_ctr_free = (i == 4);
	if (no_ctr_free) {
	i = 3;
	rdmsrl(MSR_K7_EVNTSEL3, evntsel3);
	wrmsrl(MSR_K7_EVNTSEL3, 0);
	rdmsrl(MSR_K7_PERFCTR3, pmc3);
	} else {
	reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i);
	reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
	}
	local_irq_save(flags);
	/* start meauring cycles, incrementing from 0 */
	wrmsrl(MSR_K7_PERFCTR0 + i, 0);
	wrmsrl(MSR_K7_EVNTSEL0 + i, 1 << 22 \| 3 << 16 \| 0x76);
	rdtscl(tsc_start);
	do {
	rdmsrl(MSR_K7_PERFCTR0 + i, pmc_now);
	tsc_now = get_cycles_sync();
	} while ((tsc_now - tsc_start) < TICK_COUNT);

	local_irq_restore(flags);
	if (no_ctr_free) {
	wrmsrl(MSR_K7_EVNTSEL3, 0);
	wrmsrl(MSR_K7_PERFCTR3, pmc3);
	wrmsrl(MSR_K7_EVNTSEL3, evntsel3);
	} else {
	release_perfctr_nmi(MSR_K7_PERFCTR0 + i);
	release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
	}

	return pmc_now * tsc_khz / (tsc_now - tsc_start);
	}

	/*
	* pit_calibrate_tsc() uses the speaker output (channel 2) of
	* the PIT. This is better than using the timer interrupt output,
	* because we can read the value of the speaker with just one inb(),
	* where we need three i/o operations for the interrupt channel.
	* We count how many ticks the TSC does in 50 ms.
	*/

	static unsigned int __init pit_calibrate_tsc(void)
	{
	unsigned long start, end;
	unsigned long flags;

	spin_lock_irqsave(&i8253_lock, flags);

	outb((inb(0x61) & ~0x02) \| 0x01, 0x61);

	outb(0xb0, 0x43);
	outb((PIT_TICK_RATE / (1000 / 50)) & 0xff, 0x42);
	outb((PIT_TICK_RATE / (1000 / 50)) >> 8, 0x42);
	start = get_cycles_sync();
	while ((inb(0x61) & 0x20) == 0);
	end = get_cycles_sync();

	spin_unlock_irqrestore(&i8253_lock, flags);

	return (end - start) / 50;
	}

	#define PIT_MODE 0x43
	#define PIT_CH0 0x40

	static void __pit_init(int val, u8 mode)
	{
	unsigned long flags;

	spin_lock_irqsave(&i8253_lock, flags);
	outb_p(mode, PIT_MODE);
	outb_p(val & 0xff, PIT_CH0); /* LSB */
	outb_p(val >> 8, PIT_CH0); /* MSB */
	spin_unlock_irqrestore(&i8253_lock, flags);
	}

	void __init pit_init(void)
	{
	__pit_init(LATCH, 0x34); /* binary, mode 2, LSB/MSB, ch 0 */
	}

	void pit_stop_interrupt(void)
	{
	__pit_init(0, 0x30); /* mode 0 */
	}

	void stop_timer_interrupt(void)
	{
	char *name;
	if (hpet_address) {
	name = "HPET";
	hpet_timer_stop_set_go(0);
	} else {
	name = "PIT";
	pit_stop_interrupt();
	}
	printk(KERN_INFO "timer: %s interrupt stopped.\n", name);
	}

	static struct irqaction irq0 = {
	timer_interrupt, IRQF_DISABLED, CPU_MASK_NONE, "timer", NULL, NULL
	};

	void __init time_init(void)
	{
	if (nohpet)
	hpet_address = 0;
	xtime.tv_sec = get_cmos_time();
	xtime.tv_nsec = 0;

	set_normalized_timespec(&wall_to_monotonic,
	-xtime.tv_sec, -xtime.tv_nsec);

	if (hpet_arch_init())
	hpet_address = 0;

	if (hpet_use_timer) {
	/* set tick_nsec to use the proper rate for HPET */
	tick_nsec = TICK_NSEC_HPET;
	tsc_khz = hpet_calibrate_tsc();
	timename = "HPET";
	} else {
	pit_init();
	tsc_khz = pit_calibrate_tsc();
	timename = "PIT";
	}

	cpu_khz = tsc_khz;
	if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) &&
	boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
	boot_cpu_data.x86 == 16)
	cpu_khz = tsc_calibrate_cpu_khz();

	if (unsynchronized_tsc())
	mark_tsc_unstable("TSCs unsynchronized");

	if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
	vgetcpu_mode = VGETCPU_RDTSCP;
	else
	vgetcpu_mode = VGETCPU_LSL;

	set_cyc2ns_scale(tsc_khz);
	printk(KERN_INFO "time.c: Detected %d.%03d MHz processor.\n",
	cpu_khz / 1000, cpu_khz % 1000);
	init_tsc_clocksource();

	setup_irq(0, &irq0);
	}


	static long clock_cmos_diff;
	static unsigned long sleep_start;

	/*
	* sysfs support for the timer.
	*/

	static int timer_suspend(struct sys_device *dev, pm_message_t state)
	{
	/*
	* Estimate time zone so that set_time can update the clock
	*/
	long cmos_time = get_cmos_time();

	clock_cmos_diff = -cmos_time;
	clock_cmos_diff += get_seconds();
	sleep_start = cmos_time;
	return 0;
	}

	static int timer_resume(struct sys_device *dev)
	{
	unsigned long flags;
	unsigned long sec;
	unsigned long ctime = get_cmos_time();
	long sleep_length = (ctime - sleep_start) * HZ;

	if (sleep_length < 0) {
	printk(KERN_WARNING "Time skew detected in timer resume!\n");
	/* The time after the resume must not be earlier than the time
	* before the suspend or some nasty things will happen
	*/
	sleep_length = 0;
	ctime = sleep_start;
	}
	if (hpet_address)
	hpet_reenable();
	else
	i8254_timer_resume();

	sec = ctime + clock_cmos_diff;
	write_seqlock_irqsave(&xtime_lock,flags);
	xtime.tv_sec = sec;
	xtime.tv_nsec = 0;
	jiffies += sleep_length;
	write_sequnlock_irqrestore(&xtime_lock,flags);
	touch_softlockup_watchdog();
	return 0;
	}

	static struct sysdev_class timer_sysclass = {
	.resume = timer_resume,
	.suspend = timer_suspend,
	set_kset_name("timer"),
	};

	/* XXX this sysfs stuff should probably go elsewhere later -john */
	static struct sys_device device_timer = {
	.id = 0,
	.cls = &timer_sysclass,
	};

	static int time_init_device(void)
	{
	int error = sysdev_class_register(&timer_sysclass);
	if (!error)
	error = sysdev_register(&device_timer);
	return error;
	}

	device_initcall(time_init_device);