Merge "New clock sync control loop."

    common_clock.cpp \

    main.cpp

# Uncomment to enable vesbose logging and debug service.

#TIME_SERVICE_DEBUG=true

ifeq ($(TIME_SERVICE_DEBUG), true)

LOCAL_SRC_FILES += diag_thread.cpp

LOCAL_CFLAGS += -DTIME_SERVICE_DEBUG

#include "diag_thread.h"

#endif

// Define log macro so we can make LOGV into LOGE when we are exclusively

// debugging this code.

#ifdef TIME_SERVICE_DEBUG

#define LOG_TS ALOGE

#else

#define LOG_TS ALOGV

#endif

namespace android {

ClockRecoveryLoop::ClockRecoveryLoop(LocalClock* local_clock,

    local_clock_can_slew_ = local_clock_->initCheck() &&

                           (local_clock_->setLocalSlew(0) == OK);

    computePIDParams();

    reset(true, true);

#ifdef TIME_SERVICE_DEBUG

#endif

}

// Constants.

const float ClockRecoveryLoop::dT = 1.0;

const float ClockRecoveryLoop::Kc = 1.0f;

const float ClockRecoveryLoop::Ti = 15.0f;

const float ClockRecoveryLoop::Tf = 0.05;

const float ClockRecoveryLoop::bias_Fc = 0.01;

const float ClockRecoveryLoop::bias_RC = (dT / (2 * 3.14159f * bias_Fc));

const float ClockRecoveryLoop::bias_Alpha = (dT / (bias_RC + dT));

const int64_t ClockRecoveryLoop::panic_thresh_ = 50000;

const int64_t ClockRecoveryLoop::control_thresh_ = 10000;

const float ClockRecoveryLoop::COmin = -100.0f;

const float ClockRecoveryLoop::COmax = 100.0f;

void ClockRecoveryLoop::reset(bool position, bool frequency) {

    Mutex::Autolock lock(&lock_);

    reset_l(position, frequency);

                                            int64_t rtt) {

    Mutex::Autolock lock(&lock_);

    int64_t local_common_time = 0;

    common_clock_->localToCommon(local_time, &local_common_time);

    int64_t raw_delta = nominal_common_time - local_common_time;

#ifdef TIME_SERVICE_DEBUG

    ALOGE("local=%lld, common=%lld, delta=%lld, rtt=%lld\n",

         local_common_time, nominal_common_time,

         raw_delta, rtt);

#endif

    // If we have not defined a basis for common time, then we need to use these

    // initial points to do so.  In order to avoid significant initial error

    // from a particularly bad startup data point, we collect the first N data

    int64_t observed_common;

    int64_t delta;

    int32_t delta32;

    float delta_f, dCO;

    int32_t correction_cur;

    int32_t correction_cur_P = 0;

    int32_t correction_cur_I = 0;

    int32_t correction_cur_D = 0;

    if (OK != common_clock_->localToCommon(local_time, &observed_common)) {

        // Since we just checked to make certain that this conversion was valid,

    filter_data_[filter_wr_].nominal_common_time  = nominal_common_time;

    filter_data_[filter_wr_].rtt                  = rtt;

    filter_data_[filter_wr_].point_used           = false;

    uint32_t current_point = filter_wr_;

    filter_wr_ = (filter_wr_ + 1) % kFilterSize;

    if (!filter_wr_)

        filter_full_ = true;

    // Scan the accumulated data for the point with the minimum RTT.  If that

    // point has never been used before, go ahead and use it now, otherwise just

    // do nothing.

    uint32_t scan_end = filter_full_ ? kFilterSize : filter_wr_;

    uint32_t min_rtt = findMinRTTNdx(filter_data_, scan_end);

    if (filter_data_[min_rtt].point_used)

        return true;

    local_time          = filter_data_[min_rtt].local_time;

    observed_common     = filter_data_[min_rtt].observed_common_time;

    nominal_common_time = filter_data_[min_rtt].nominal_common_time;

    filter_data_[min_rtt].point_used = true;

    // Compute the error then clamp to the panic threshold.  If we ever exceed

    // this amt of error, its time to panic and reset the system.  Given that

    // the error in the measurement of the error could be as high as the RTT of

    // the data point, we don't actually panic until the implied error (delta)

    // is greater than the absolute panic threashold plus the RTT.  IOW - we

    // don't panic until we are absoluely sure that our best case sync is worse

    // than the absolute panic threshold.

    int64_t effective_panic_thresh = panic_thresh_ + filter_data_[min_rtt].rtt;

    delta = nominal_common_time - observed_common;

    if ((delta > effective_panic_thresh) || (delta < -effective_panic_thresh)) {

    // We only use packets with low RTTs for control. If the packet RTT

    // is less than the panic threshold, we can probably eat the jitter with the

    // control loop. Otherwise, take the packet only if it better than all

    // of the packets we have in the history. That way we try to track

    // something, even if it is noisy.

    if (current_point == min_rtt || rtt < control_thresh_) {

        delta_f = delta = nominal_common_time - observed_common;

        // Compute the error then clamp to the panic threshold.  If we ever

        // exceed this amt of error, its time to panic and reset the system.

        // Given that the error in the measurement of the error could be as

        // high as the RTT of the data point, we don't actually panic until

        // the implied error (delta) is greater than the absolute panic

        // threashold plus the RTT.  IOW - we don't panic until we are

        // absoluely sure that our best case sync is worse than the absolute

        // panic threshold.

        int64_t effective_panic_thresh = panic_thresh_ + rtt;

        if ((delta > effective_panic_thresh) ||

            (delta < -effective_panic_thresh)) {

            // PANIC!!!

        //

        // TODO(johngro) : need to report this to the upper levels of

        // code.

            reset_l(false, true);

            return false;

    } else

        delta32 = delta;

    // Accumulate error into the integrated error, then clamp.

    integrated_error_ += delta32;

    if (integrated_error_ > pid_params_.integrated_delta_max)

        integrated_error_ = pid_params_.integrated_delta_max;

    else if (integrated_error_ < pid_params_.integrated_delta_min)

        integrated_error_ = pid_params_.integrated_delta_min;

    // Compute the difference in error between last time and this time, then

    // update last_delta_

    int32_t input_D = last_delta_valid_ ? delta32 - last_delta_ : 0;

    last_delta_valid_ = true;

    last_delta_ = delta32;

    // Compute the various components of the correction value.

    correction_cur_P = doGainScale(pid_params_.gain_P, delta32);

    correction_cur_I = doGainScale(pid_params_.gain_I, integrated_error_);

    // TODO(johngro) : the differential portion of this code used to rely

    // upon a completely homogeneous discipline frequency.  Now that the

    // discipline frequency may not be homogeneous, its probably important

    // to divide by the amt of time between discipline events during the

    // gain calculation.

    correction_cur_D = doGainScale(pid_params_.gain_D, input_D);

    // Compute the final correction value and clamp.

    correction_cur = correction_cur_P + correction_cur_I + correction_cur_D;

    if (correction_cur < pid_params_.correction_min)

        correction_cur = pid_params_.correction_min;

    else if (correction_cur > pid_params_.correction_max)

        correction_cur = pid_params_.correction_max;

        }

    } else {

        // We do not have a good packet to look at, but we also do not want to

        // free-run the clock at some crazy slew rate. So we guess the

        // trajectory of the clock based on the last controller output and the

        // estimated bias of our clock against the master.

        // The net effect of this is that CO == CObias after some extended

        // period of no feedback.

        delta_f = last_delta_f_ - dT*(CO - CObias);

        delta = delta_f;

    }

    // Velocity form PI control equation.

    dCO = Kc * (1.0f + dT/Ti) * delta_f - Kc * last_delta_f_;

    CO += dCO * Tf; // Filter CO by applying gain <1 here.

    // Save error terms for later.

    last_delta_f_ = delta_f;

    last_delta_ = delta;

    // Clamp CO to +/- 100ppm.

    if (CO < COmin)

        CO = COmin;

    else if (CO > COmax)

        CO = COmax;

    // Update the controller bias.

    CObias = bias_Alpha * CO + (1.0f - bias_Alpha) * lastCObias;

    lastCObias = CObias;

    // Convert PPM to 16-bit int range. Add some guard band (-0.01) so we

    // don't get fp weirdness.

    correction_cur = CO * 327.66;

    // If there was a change in the amt of correction to use, update the

    // system.

        applySlew();

    }

    ALOGV("rtt %lld observed %lld nominal %lld delta = %5lld "

          "int = %7d correction %5d (P %5d, I %5d, D %5d)\n",

          filter_data_[min_rtt].rtt,

          observed_common,

          nominal_common_time,

          nominal_common_time - observed_common,

          integrated_error_,

          correction_cur,

          correction_cur_P,

          correction_cur_I,

          correction_cur_D);

    LOG_TS("clock_loop %lld %f %f %f %d\n", raw_delta, delta_f, CO, CObias, correction_cur);

#ifdef TIME_SERVICE_DEBUG

    diag_thread_->pushDisciplineEvent(

            observed_common,

            nominal_common_time,

            correction_cur,

            correction_cur_P,

            correction_cur_I,

            correction_cur_D);

            rtt);

#endif

    return true;

        return ICommonClock::kErrorEstimateUnknown;

}

void ClockRecoveryLoop::computePIDParams() {

    // TODO(johngro) : add the ability to fetch parameters from the driver/board

    // level in case they have a HW clock discipline solution with parameters

    // tuned specifically for it.

    // Correction factor is limited to MIN/MAX_INT_16

    pid_params_.correction_min = -0x8000;

    pid_params_.correction_max =  0x7FFF;

    // Default proportional gain to 2^15:1000.  (max proportional drive at 1mSec

    // of instantaneous error)

    memset(&pid_params_.gain_P, 0, sizeof(pid_params_.gain_P));

    pid_params_.gain_P.a_to_b_numer = 0x8000;

    pid_params_.gain_P.a_to_b_denom = 1000;

    // Set the integral gain to 2^15:5000

    memset(&pid_params_.gain_I, 0, sizeof(pid_params_.gain_I));

    pid_params_.gain_I.a_to_b_numer = 0x8000;

    pid_params_.gain_I.a_to_b_denom = 5000;

    // Default controller is just a PI controller.  Right now, the network based

    // measurements of the error are way to noisy to feed into the differential

    // component of a PID controller.  Someday we might come back and add some

    // filtering of the error channel, but until then leave the controller as a

    // simple PI controller.

    memset(&pid_params_.gain_D, 0, sizeof(pid_params_.gain_D));

    // Don't let the integral component of the controller wind up to

    // the point where it would want to drive the correction factor

    // past saturation.

    int64_t tmp;

    pid_params_.gain_I.doReverseTransform(pid_params_.correction_min, &tmp);

    pid_params_.integrated_delta_min = static_cast<int32_t>(tmp);

    pid_params_.gain_I.doReverseTransform(pid_params_.correction_max, &tmp);

    pid_params_.integrated_delta_max = static_cast<int32_t>(tmp);

    // By default, panic when are certain that the sync error is > 20mSec;

    panic_thresh_ = 20000;

}

void ClockRecoveryLoop::reset_l(bool position, bool frequency) {

    assert(NULL != common_clock_);

    if (frequency) {

        last_delta_valid_ = false;

        last_delta_ = 0;

        integrated_error_ = 0;

        correction_cur_ = 0;

        last_delta_f_ = 0.0;

        correction_cur_ = 0x0;

        CO = 0.0f;

        lastCObias = CObias = 0.0f;

        applySlew();

    }

    filter_full_ = false;

}

int32_t ClockRecoveryLoop::doGainScale(const LinearTransform& gain,

                                       int32_t val) {

    if (!gain.a_to_b_numer || !gain.a_to_b_denom || !val)

        return 0;

    int64_t tmp;

    int64_t val64 = static_cast<int64_t>(val);

    if (!gain.doForwardTransform(val64, &tmp)) {

        ALOGW("Overflow/Underflow while scaling %d in %s",

             val, __PRETTY_FUNCTION__);

        return (val < 0) ? INT32_MIN : INT32_MAX;

    }

    if (tmp > INT32_MAX) {

        ALOGW("Overflow while scaling %d in %s", val, __PRETTY_FUNCTION__);

        return INT32_MAX;

    }

    if (tmp < INT32_MIN) {

        ALOGW("Underflow while scaling %d in %s", val, __PRETTY_FUNCTION__);

        return INT32_MIN;

    }

    return static_cast<int32_t>(tmp);

}

void ClockRecoveryLoop::applySlew() {

    if (local_clock_can_slew_) {

        local_clock_->setLocalSlew(correction_cur_);

    } else {

        // The SW clock recovery implemented by the common clock class expects

        // values expressed in PPM.  Map the MIN/MAX_INT_16 drive range to +/-

        // 100ppm.

        int sw_correction;

        sw_correction  = correction_cur_ - pid_params_.correction_min;

        sw_correction *= 200;

        sw_correction /= (pid_params_.correction_max -

                          pid_params_.correction_min);

        sw_correction -= 100;

        common_clock_->setSlew(local_clock_->getLocalTime(), sw_correction);

        // values expressed in PPM. CO is in ppm.

        common_clock_->setSlew(local_clock_->getLocalTime(), CO);

    }

}

    int32_t getLastErrorEstimate();

  private:

    typedef struct {

        // Limits for the correction factor supplied to set_counter_slew_rate.

        // The controller will always clamp its output to the range expressed by

        // correction_(min|max)

        int32_t correction_min;

        int32_t correction_max;

        // Limits for the internal integration accumulator in the PID

        // controller.  The value of the accumulator is scaled by gain_I to

        // produce the integral component of the PID controller output.

        // Platforms can use these limits to prevent windup in the system

        // if/when the correction factor needs to be driven to saturation for

        // extended periods of time.

        int32_t integrated_delta_min;

        int32_t integrated_delta_max;

        // Gain for the P, I and D components of the controller.

        LinearTransform gain_P;

        LinearTransform gain_I;

        LinearTransform gain_D;

    } PIDParams;

    // Tuned using the "Good Gain" method.

    // See:

    // http://techteach.no/publications/books/dynamics_and_control/tuning_pid_controller.pdf

    // Controller period (1Hz for now).

    static const float dT;

    // Controller gain, positive and unitless. Larger values converge faster,

    // but can cause instability.

    static const float Kc;

    // Integral reset time. Smaller values cause loop to track faster, but can

    // also cause instability.

    static const float Ti;

    // Controller output filter time constant. Range (0-1). Smaller values make

    // output smoother, but slow convergence.

    static const float Tf;

    // Low-pass filter for bias tracker.

    static const float bias_Fc; // HZ

    static const float bias_RC; // Computed in constructor.

    static const float bias_Alpha; // Computed inconstructor.

    // The maximum allowed error (as indicated by a  pushDisciplineEvent) before

    // we panic.

    static const int64_t panic_thresh_;

    // The maximum allowed error rtt time for packets to be used for control

    // feedback, unless the packet is the best in recent memory.

    static const int64_t control_thresh_;

    typedef struct {

        int64_t local_time;

    static uint32_t findMinRTTNdx(DisciplineDataPoint* data, uint32_t count);

    void computePIDParams();

    void reset_l(bool position, bool frequency);

    static int32_t doGainScale(const LinearTransform& gain, int32_t val);

    void applySlew();

    // The local clock HW abstraction we use as the basis for common time.

    CommonClock* common_clock_;

    Mutex lock_;

    // The parameters computed to be used for the PID Controller.

    PIDParams pid_params_;

    // The maximum allowed error (as indicated by a  pushDisciplineEvent) before

    // we panic.

    int32_t panic_thresh_;

    // parameters maintained while running and reset during a reset

    // of the frequency correction.

    bool    last_delta_valid_;

    int32_t last_delta_;

    float last_delta_f_;

    int32_t integrated_error_;

    int32_t correction_cur_;

    // Contoller Output.

    float CO;

    // Bias tracking for trajectory estimation.

    float CObias;

    float lastCObias;

    // Controller output bounds. The controller will not try to

    // slew faster that +/-100ppm offset from center per interation.

    static const float COmin;

    static const float COmax;

    // State kept for filtering the discipline data.

    static const uint32_t kFilterSize = 6;

    static const uint32_t kFilterSize = 16;

    DisciplineDataPoint filter_data_[kFilterSize];

    uint32_t filter_wr_;

    bool filter_full_;

            if (shouldPanicNotGettingGoodData())

                return becomeInitial("RX panic, no good data");

        } else {

            result = mClockRecovery.pushDisciplineEvent(avgLocal, avgCommon, rtt);

            result = mClockRecovery.pushDisciplineEvent(avgLocal, avgCommon, rttCommon);

            mClient_LastGoodSyncRX = clientRxLocalTime;

            if (result) {

}  // namespace android

#endif  // ANDROID_COMMON_TIME_SERVER_H