xnu-1228.15.4.tar.gz

[apple/xnu.git] / osfmk / i386 / rtclock.c

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 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
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 * Please obtain a copy of the License at
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/*
 * @OSF_COPYRIGHT@
 */

/*
 *      File:           i386/rtclock.c
 *      Purpose:        Routines for handling the machine dependent
 *                      real-time clock. Historically, this clock is
 *                      generated by the Intel 8254 Programmable Interval
 *                      Timer, but local apic timers are now used for
 *                      this purpose with the master time reference being
 *                      the cpu clock counted by the timestamp MSR.
 */

#include <platforms.h>
#include <mach_kdb.h>

#include <mach/mach_types.h>

#include <kern/cpu_data.h>
#include <kern/cpu_number.h>
#include <kern/clock.h>
#include <kern/host_notify.h>
#include <kern/macro_help.h>
#include <kern/misc_protos.h>
#include <kern/spl.h>
#include <kern/assert.h>
#include <mach/vm_prot.h>
#include <vm/pmap.h>
#include <vm/vm_kern.h>         /* for kernel_map */
#include <i386/ipl.h>
#include <architecture/i386/pio.h>
#include <i386/misc_protos.h>
#include <i386/proc_reg.h>
#include <i386/machine_cpu.h>
#include <i386/lapic.h>
#include <i386/cpuid.h>
#include <i386/cpu_data.h>
#include <i386/cpu_threads.h>
#include <i386/perfmon.h>
#include <i386/machine_routines.h>
#include <pexpert/pexpert.h>
#include <machine/limits.h>
#include <machine/commpage.h>
#include <sys/kdebug.h>
#include <i386/tsc.h>
#include <i386/rtclock.h>

#define NSEC_PER_HZ                     (NSEC_PER_SEC / 100) /* nsec per tick */

#define UI_CPUFREQ_ROUNDING_FACTOR      10000000

int             rtclock_config(void);

int             rtclock_init(void);

uint64_t        rtc_decrementer_min;

void                    rtclock_intr(x86_saved_state_t *regs);
static uint64_t         maxDec;                 /* longest interval our hardware timer can handle (nsec) */

static void     rtc_set_timescale(uint64_t cycles);
static uint64_t rtc_export_speed(uint64_t cycles);

rtc_nanotime_t  rtc_nanotime_info = {0,0,0,0,1,0};

/*
 * tsc_to_nanoseconds:
 *
 * Basic routine to convert a raw 64 bit TSC value to a
 * 64 bit nanosecond value.  The conversion is implemented
 * based on the scale factor and an implicit 32 bit shift.
 */
static inline uint64_t
_tsc_to_nanoseconds(uint64_t value)
{
    asm volatile("movl  %%edx,%%esi     ;"
                 "mull  %%ecx           ;"
                 "movl  %%edx,%%edi     ;"
                 "movl  %%esi,%%eax     ;"
                 "mull  %%ecx           ;"
                 "addl  %%edi,%%eax     ;"      
                 "adcl  $0,%%edx         "
                 : "+A" (value)
                 : "c" (current_cpu_datap()->cpu_nanotime->scale)
                 : "esi", "edi");

    return (value);
}

static uint32_t
deadline_to_decrementer(
        uint64_t        deadline,
        uint64_t        now)
{
        uint64_t        delta;

        if (deadline <= now)
                return rtc_decrementer_min;
        else {
                delta = deadline - now;
                return MIN(MAX(rtc_decrementer_min,delta),maxDec); 
        }
}

void
rtc_lapic_start_ticking(void)
{
        x86_lcpu_t      *lcpu = x86_lcpu();

        /*
         * Force a complete re-evaluation of timer deadlines.
         */
        lcpu->rtcPop = EndOfAllTime;
        etimer_resync_deadlines();
}

/*
 * Configure the real-time clock device. Return success (1)
 * or failure (0).
 */

int
rtclock_config(void)
{
        /* nothing to do */
        return (1);
}


/*
 * Nanotime/mach_absolutime_time
 * -----------------------------
 * The timestamp counter (TSC) - which counts cpu clock cycles and can be read
 * efficiently by the kernel and in userspace - is the reference for all timing.
 * The cpu clock rate is platform-dependent and may stop or be reset when the
 * processor is napped/slept.  As a result, nanotime is the software abstraction
 * used to maintain a monotonic clock, adjusted from an outside reference as needed.
 *
 * The kernel maintains nanotime information recording:
 *      - the ratio of tsc to nanoseconds
 *        with this ratio expressed as a 32-bit scale and shift
 *        (power of 2 divider);
 *      - { tsc_base, ns_base } pair of corresponding timestamps.
 *
 * The tuple {tsc_base, ns_base, scale, shift} is exported in the commpage 
 * for the userspace nanotime routine to read.
 *
 * All of the routines which update the nanotime data are non-reentrant.  This must
 * be guaranteed by the caller.
 */
static inline void
rtc_nanotime_set_commpage(rtc_nanotime_t *rntp)
{
        commpage_set_nanotime(rntp->tsc_base, rntp->ns_base, rntp->scale, rntp->shift);
}

/*
 * rtc_nanotime_init:
 *
 * Intialize the nanotime info from the base time.
 */
static inline void
_rtc_nanotime_init(rtc_nanotime_t *rntp, uint64_t base)
{
        uint64_t        tsc = rdtsc64();

        _rtc_nanotime_store(tsc, base, rntp->scale, rntp->shift, rntp);
}

static void
rtc_nanotime_init(uint64_t base)
{
        rtc_nanotime_t  *rntp = current_cpu_datap()->cpu_nanotime;

        _rtc_nanotime_init(rntp, base);
        rtc_nanotime_set_commpage(rntp);
}

/*
 * rtc_nanotime_init_commpage:
 *
 * Call back from the commpage initialization to
 * cause the commpage data to be filled in once the
 * commpages have been created.
 */
void
rtc_nanotime_init_commpage(void)
{
        spl_t                   s = splclock();

        rtc_nanotime_set_commpage(current_cpu_datap()->cpu_nanotime);

        splx(s);
}

/*
 * rtc_nanotime_read:
 *
 * Returns the current nanotime value, accessable from any
 * context.
 */
static inline uint64_t
rtc_nanotime_read(void)
{
        
#if CONFIG_EMBEDDED
        if (gPEClockFrequencyInfo.timebase_frequency_hz > SLOW_TSC_THRESHOLD)
                return  _rtc_nanotime_read(current_cpu_datap()->cpu_nanotime, 1);       /* slow processor */
        else
#endif
        return  _rtc_nanotime_read(current_cpu_datap()->cpu_nanotime, 0);       /* assume fast processor */
}

/*
 * rtc_clock_napped:
 *
 * Invoked from power management when we exit from a low C-State (>= C4)
 * and the TSC has stopped counting.  The nanotime data is updated according
 * to the provided value which represents the new value for nanotime.
 */
void
rtc_clock_napped(uint64_t base, uint64_t tsc_base)
{
        rtc_nanotime_t  *rntp = current_cpu_datap()->cpu_nanotime;
        uint64_t        oldnsecs;
        uint64_t        newnsecs;
        uint64_t        tsc;

        assert(!ml_get_interrupts_enabled());
        tsc = rdtsc64();
        oldnsecs = rntp->ns_base + _tsc_to_nanoseconds(tsc - rntp->tsc_base);
        newnsecs = base + _tsc_to_nanoseconds(tsc - tsc_base);
        
        /*
         * Only update the base values if time using the new base values
         * is later than the time using the old base values.
         */
        if (oldnsecs < newnsecs) {
            _rtc_nanotime_store(tsc_base, base, rntp->scale, rntp->shift, rntp);
            rtc_nanotime_set_commpage(rntp);
        }
}

void
rtc_clock_stepping(__unused uint32_t new_frequency,
                   __unused uint32_t old_frequency)
{
        panic("rtc_clock_stepping unsupported");
}

void
rtc_clock_stepped(__unused uint32_t new_frequency,
                  __unused uint32_t old_frequency)
{
        panic("rtc_clock_stepped unsupported");
}

/*
 * rtc_sleep_wakeup:
 *
 * Invoked from power manageent when we have awoken from a sleep (S3)
 * and the TSC has been reset.  The nanotime data is updated based on
 * the passed in value.
 *
 * The caller must guarantee non-reentrancy.
 */
void
rtc_sleep_wakeup(
        uint64_t                base)
{
        /*
         * Reset nanotime.
         * The timestamp counter will have been reset
         * but nanotime (uptime) marches onward.
         */
        rtc_nanotime_init(base);
}

/*
 * Initialize the real-time clock device.
 * In addition, various variables used to support the clock are initialized.
 */
int
rtclock_init(void)
{
        uint64_t        cycles;

        assert(!ml_get_interrupts_enabled());

        if (cpu_number() == master_cpu) {

                assert(tscFreq);
                rtc_set_timescale(tscFreq);

                /*
                 * Adjust and set the exported cpu speed.
                 */
                cycles = rtc_export_speed(tscFreq);

                /*
                 * Set min/max to actual.
                 * ACPI may update these later if speed-stepping is detected.
                 */
                gPEClockFrequencyInfo.cpu_frequency_min_hz = cycles;
                gPEClockFrequencyInfo.cpu_frequency_max_hz = cycles;

                /*
                 * Compute the longest interval we can represent.
                 */
                maxDec = tmrCvt(0x7fffffffULL, busFCvtt2n);
                kprintf("maxDec: %lld\n", maxDec);

                /* Minimum interval is 1usec */
                rtc_decrementer_min = deadline_to_decrementer(NSEC_PER_USEC, 0ULL);
                /* Point LAPIC interrupts to hardclock() */
                lapic_set_timer_func((i386_intr_func_t) rtclock_intr);

                clock_timebase_init();
                ml_init_lock_timeout();
        }

        rtc_lapic_start_ticking();

        return (1);
}

// utility routine 
// Code to calculate how many processor cycles are in a second...

static void
rtc_set_timescale(uint64_t cycles)
{
        rtc_nanotime_t  *rntp = current_cpu_datap()->cpu_nanotime;
        rntp->scale = ((uint64_t)NSEC_PER_SEC << 32) / cycles;

        if (cycles <= SLOW_TSC_THRESHOLD)
                rntp->shift = cycles;
        else
                rntp->shift = 32;

        rtc_nanotime_init(0);
}

static uint64_t
rtc_export_speed(uint64_t cyc_per_sec)
{
        uint64_t        cycles;

        /* Round: */
        cycles = ((cyc_per_sec + (UI_CPUFREQ_ROUNDING_FACTOR/2))
                        / UI_CPUFREQ_ROUNDING_FACTOR)
                                * UI_CPUFREQ_ROUNDING_FACTOR;

        /*
         * Set current measured speed.
         */
        if (cycles >= 0x100000000ULL) {
            gPEClockFrequencyInfo.cpu_clock_rate_hz = 0xFFFFFFFFUL;
        } else {
            gPEClockFrequencyInfo.cpu_clock_rate_hz = (unsigned long)cycles;
        }
        gPEClockFrequencyInfo.cpu_frequency_hz = cycles;

        kprintf("[RTCLOCK] frequency %llu (%llu)\n", cycles, cyc_per_sec);
        return(cycles);
}

void
clock_get_system_microtime(
        uint32_t                        *secs,
        uint32_t                        *microsecs)
{
        uint64_t        now = rtc_nanotime_read();
        uint32_t        remain;

        asm volatile(
                        "divl %3"
                                : "=a" (*secs), "=d" (remain)
                                : "A" (now), "r" (NSEC_PER_SEC));
        asm volatile(
                        "divl %3"
                                : "=a" (*microsecs)
                                : "0" (remain), "d" (0), "r" (NSEC_PER_USEC));
}

void
clock_get_system_nanotime(
        uint32_t                        *secs,
        uint32_t                        *nanosecs)
{
        uint64_t        now = rtc_nanotime_read();

        asm volatile(
                        "divl %3"
                                : "=a" (*secs), "=d" (*nanosecs)
                                : "A" (now), "r" (NSEC_PER_SEC));
}

void
clock_gettimeofday_set_commpage(
        uint64_t                                abstime,
        uint64_t                                epoch,
        uint64_t                                offset,
        uint32_t                                *secs,
        uint32_t                                *microsecs)
{
        uint64_t        now = abstime;
        uint32_t        remain;

        now += offset;

        asm volatile(
                        "divl %3"
                                : "=a" (*secs), "=d" (remain)
                                : "A" (now), "r" (NSEC_PER_SEC));
        asm volatile(
                        "divl %3"
                                : "=a" (*microsecs)
                                : "0" (remain), "d" (0), "r" (NSEC_PER_USEC));

        *secs += epoch;

        commpage_set_timestamp(abstime - remain, *secs);
}

void
clock_timebase_info(
        mach_timebase_info_t    info)
{
        info->numer = info->denom =  1;
}       

/*
 * Real-time clock device interrupt.
 */
void
rtclock_intr(
        x86_saved_state_t       *tregs)
{
        uint64_t        rip;
        boolean_t       user_mode = FALSE;
        uint64_t        abstime;
        uint32_t        latency;
        x86_lcpu_t      *lcpu = x86_lcpu();

        assert(get_preemption_level() > 0);
        assert(!ml_get_interrupts_enabled());

        abstime = rtc_nanotime_read();
        latency = (uint32_t)(abstime - lcpu->rtcDeadline);
        if (abstime < lcpu->rtcDeadline)
                latency = 1;

        if (is_saved_state64(tregs) == TRUE) {
                x86_saved_state64_t     *regs;
                  
                regs = saved_state64(tregs);

                user_mode = TRUE;
                rip = regs->isf.rip;
        } else {
                x86_saved_state32_t     *regs;

                regs = saved_state32(tregs);

                if (regs->cs & 0x03)
                        user_mode = TRUE;
                rip = regs->eip;
        }

        /* Log the interrupt service latency (-ve value expected by tool) */
        KERNEL_DEBUG_CONSTANT(
                MACHDBG_CODE(DBG_MACH_EXCP_DECI, 0) | DBG_FUNC_NONE,
                -latency, (uint32_t)rip, user_mode, 0, 0);

        /* call the generic etimer */
        etimer_intr(user_mode, rip);
}

/*
 *      Request timer pop from the hardware 
 */

int
setPop(
        uint64_t time)
{
        uint64_t now;
        uint32_t decr;
        uint64_t count;
        
        now = rtc_nanotime_read();              /* The time in nanoseconds */
        decr = deadline_to_decrementer(time, now);

        count = tmrCvt(decr, busFCvtn2t);
        lapic_set_timer(TRUE, one_shot, divide_by_1, (uint32_t) count);

        return decr;                            /* Pass back what we set */
}


uint64_t
mach_absolute_time(void)
{
        return rtc_nanotime_read();
}

void
clock_interval_to_absolutetime_interval(
        uint32_t                interval,
        uint32_t                scale_factor,
        uint64_t                *result)
{
        *result = (uint64_t)interval * scale_factor;
}

void
absolutetime_to_microtime(
        uint64_t                        abstime,
        uint32_t                        *secs,
        uint32_t                        *microsecs)
{
        uint32_t        remain;

        asm volatile(
                        "divl %3"
                                : "=a" (*secs), "=d" (remain)
                                : "A" (abstime), "r" (NSEC_PER_SEC));
        asm volatile(
                        "divl %3"
                                : "=a" (*microsecs)
                                : "0" (remain), "d" (0), "r" (NSEC_PER_USEC));
}

void
absolutetime_to_nanotime(
        uint64_t                        abstime,
        uint32_t                        *secs,
        uint32_t                        *nanosecs)
{
        asm volatile(
                        "divl %3"
                        : "=a" (*secs), "=d" (*nanosecs)
                        : "A" (abstime), "r" (NSEC_PER_SEC));
}

void
nanotime_to_absolutetime(
        uint32_t                        secs,
        uint32_t                        nanosecs,
        uint64_t                        *result)
{
        *result = ((uint64_t)secs * NSEC_PER_SEC) + nanosecs;
}

void
absolutetime_to_nanoseconds(
        uint64_t                abstime,
        uint64_t                *result)
{
        *result = abstime;
}

void
nanoseconds_to_absolutetime(
        uint64_t                nanoseconds,
        uint64_t                *result)
{
        *result = nanoseconds;
}

void
machine_delay_until(
        uint64_t                deadline)
{
        uint64_t                now;

        do {
                cpu_pause();
                now = mach_absolute_time();
        } while (now < deadline);
}