/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2017 by Delphix. All rights reserved.
 */
/*
 * Copyright (c) 2010, Intel Corporation.
 * All rights reserved.
 */
/*
 * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
 */

#include <sys/time.h>
#include <sys/psm.h>
#include <sys/psm_common.h>
#include <sys/apic.h>
#include <sys/pit.h>
#include <sys/x86_archext.h>
#include <sys/archsystm.h>
#include <sys/machsystm.h>
#include <sys/cpuvar.h>
#include <sys/clock.h>
#include <sys/apic_timer.h>

/*
 * preferred apic timer mode, allow tuning from the /etc/system file.
 */
int             apic_timer_preferred_mode = APIC_TIMER_MODE_DEADLINE;

int             apic_oneshot = 0;
uint_t          apic_hertz_count;
uint_t          apic_nsec_per_intr = 0;
uint64_t        apic_ticks_per_SFnsecs;         /* # of ticks in SF nsecs */

static int              apic_min_timer_ticks = 1; /* minimum timer tick */
static hrtime_t         apic_nsec_max;

static void     periodic_timer_enable(void);
static void     periodic_timer_disable(void);
static void     periodic_timer_reprogram(hrtime_t);
static void     oneshot_timer_enable(void);
static void     oneshot_timer_disable(void);
static void     oneshot_timer_reprogram(hrtime_t);
static void     deadline_timer_enable(void);
static void     deadline_timer_disable(void);
static void     deadline_timer_reprogram(hrtime_t);

extern int      apic_clkvect;
extern uint32_t apic_divide_reg_init;

/*
 * apic timer data structure
 */
typedef struct apic_timer {
        int     mode;
        void    (*apic_timer_enable_ops)(void);
        void    (*apic_timer_disable_ops)(void);
        void    (*apic_timer_reprogram_ops)(hrtime_t);
} apic_timer_t;

static apic_timer_t     apic_timer;

/*
 * apic timer initialization
 *
 * For the one-shot mode request case, the function returns the
 * resolution (in nanoseconds) for the hardware timer interrupt.
 * If one-shot mode capability is not available, the return value
 * will be 0.
 */
int
apic_timer_init(int hertz)
{
        int             ret, timer_mode;
        static int      firsttime = 1;

        if (firsttime) {
                /* first time calibrate on CPU0 only */
                apic_ticks_per_SFnsecs = apic_calibrate();

                /* the interval timer initial count is 32 bit max */
                apic_nsec_max = APIC_TICKS_TO_NSECS(APIC_MAXVAL);
                firsttime = 0;
        }

        if (hertz == 0) {
                /* requested one_shot */

                /*
                 * return 0 if TSC is not supported.
                 */
                if (!tsc_gethrtime_enable)
                        return (0);
                /*
                 * return 0 if one_shot is not preferred.
                 * here, APIC_TIMER_DEADLINE is also an one_shot mode.
                 */
                if ((apic_timer_preferred_mode != APIC_TIMER_MODE_ONESHOT) &&
                    (apic_timer_preferred_mode != APIC_TIMER_MODE_DEADLINE))
                        return (0);

                apic_oneshot = 1;
                ret = (int)APIC_TICKS_TO_NSECS(1);
                if ((apic_timer_preferred_mode == APIC_TIMER_MODE_DEADLINE) &&
                    cpuid_deadline_tsc_supported()) {
                        timer_mode = APIC_TIMER_MODE_DEADLINE;
                } else {
                        timer_mode = APIC_TIMER_MODE_ONESHOT;
                }
        } else {
                /* periodic */
                apic_nsec_per_intr = NANOSEC / hertz;
                apic_hertz_count = APIC_NSECS_TO_TICKS(apic_nsec_per_intr);

                /* program the local APIC to interrupt at the given frequency */
                apic_reg_ops->apic_write(APIC_INIT_COUNT, apic_hertz_count);
                apic_reg_ops->apic_write(APIC_LOCAL_TIMER,
                    (apic_clkvect + APIC_BASE_VECT) | AV_PERIODIC);
                apic_oneshot = 0;
                timer_mode = APIC_TIMER_MODE_PERIODIC;
                ret = NANOSEC / hertz;
        }

        /*
         * initialize apic_timer data structure, install the timer ops
         */
        apic_timer.mode = timer_mode;
        switch (timer_mode) {
        default:
                /* FALLTHROUGH */
        case APIC_TIMER_MODE_ONESHOT:
                apic_timer.apic_timer_enable_ops = oneshot_timer_enable;
                apic_timer.apic_timer_disable_ops = oneshot_timer_disable;
                apic_timer.apic_timer_reprogram_ops = oneshot_timer_reprogram;
                break;

        case APIC_TIMER_MODE_PERIODIC:
                apic_timer.apic_timer_enable_ops = periodic_timer_enable;
                apic_timer.apic_timer_disable_ops = periodic_timer_disable;
                apic_timer.apic_timer_reprogram_ops = periodic_timer_reprogram;
                break;

        case APIC_TIMER_MODE_DEADLINE:
                apic_timer.apic_timer_enable_ops = deadline_timer_enable;
                apic_timer.apic_timer_disable_ops = deadline_timer_disable;
                apic_timer.apic_timer_reprogram_ops = deadline_timer_reprogram;
                break;
        }

        return (ret);
}

/*
 * periodic timer mode ops
 */
/* periodic timer enable */
static void
periodic_timer_enable(void)
{
        apic_reg_ops->apic_write(APIC_LOCAL_TIMER,
            (apic_clkvect + APIC_BASE_VECT) | AV_PERIODIC);
}

/* periodic timer disable */
static void
periodic_timer_disable(void)
{
        apic_reg_ops->apic_write(APIC_LOCAL_TIMER,
            (apic_clkvect + APIC_BASE_VECT) | AV_MASK);
}

/* periodic timer reprogram */
static void
periodic_timer_reprogram(hrtime_t time)
{
        uint_t  ticks;
        /* time is the interval for periodic mode */
        ticks = APIC_NSECS_TO_TICKS(time);

        if (ticks < apic_min_timer_ticks)
                ticks = apic_min_timer_ticks;

        apic_reg_ops->apic_write(APIC_INIT_COUNT, ticks);
}

/*
 * oneshot timer mode ops
 */
/* oneshot timer enable */
static void
oneshot_timer_enable(void)
{
        apic_reg_ops->apic_write(APIC_LOCAL_TIMER,
            (apic_clkvect + APIC_BASE_VECT));
}

/* oneshot timer disable */
static void
oneshot_timer_disable(void)
{
        apic_reg_ops->apic_write(APIC_LOCAL_TIMER,
            (apic_clkvect + APIC_BASE_VECT) | AV_MASK);
}

/* oneshot timer reprogram */
static void
oneshot_timer_reprogram(hrtime_t time)
{
        hrtime_t        now;
        int64_t         delta;
        uint_t          ticks;

        now = gethrtime();
        delta = time - now;

        if (delta <= 0) {
                /*
                 * requested to generate an interrupt in the past
                 * generate an interrupt as soon as possible
                 */
                ticks = apic_min_timer_ticks;
        } else if (delta > apic_nsec_max) {
                /*
                 * requested to generate an interrupt at a time
                 * further than what we are capable of. Set to max
                 * the hardware can handle
                 */
                ticks = APIC_MAXVAL;
#ifdef DEBUG
                cmn_err(CE_CONT, "apic_timer_reprogram, request at"
                    "  %lld  too far in future, current time"
                    "  %lld \n", time, now);
#endif
        } else {
                ticks = APIC_NSECS_TO_TICKS(delta);
        }

        if (ticks < apic_min_timer_ticks)
                ticks = apic_min_timer_ticks;

        apic_reg_ops->apic_write(APIC_INIT_COUNT, ticks);
}

/*
 * deadline timer mode ops
 */
/* deadline timer enable */
static void
deadline_timer_enable(void)
{
        uint64_t ticks;

        apic_reg_ops->apic_write(APIC_LOCAL_TIMER,
            (apic_clkvect + APIC_BASE_VECT) | AV_DEADLINE);
        /*
         * Now we have to serialize this per the SDM.  That is to
         * say, the above enabling can race in the pipeline with
         * changes to the MSR.  We need to make sure the above
         * operation is complete before we proceed to reprogram
         * the deadline value in reprogram().  The algorithm
         * recommended by the Intel SDM 3A in 10.5.1.4 is:
         *
         * a) write a big value to the deadline register
         * b) read the register back
         * c) if it reads zero, go back to a and try again
         */

        do {
                /* write a really big value */
                wrmsr(IA32_DEADLINE_TSC_MSR, 1ULL << 63);
                ticks = rdmsr(IA32_DEADLINE_TSC_MSR);
        } while (ticks == 0);
}

/* deadline timer disable */
static void
deadline_timer_disable(void)
{
        apic_reg_ops->apic_write(APIC_LOCAL_TIMER,
            (apic_clkvect + APIC_BASE_VECT) | AV_MASK);
}

/* deadline timer reprogram */
static void
deadline_timer_reprogram(hrtime_t time)
{
        int64_t         delta;
        uint64_t        ticks;

        /*
         * Note that this entire routine is called with
         * CBE_HIGH_PIL, so we needn't worry about preemption.
         */
        delta = time - gethrtime();

        /* The unscalehrtime wants unsigned values. */
        delta = max(delta, 0);

        /* Now we shouldn't be interrupted, we can set the deadline */
        ticks = (uint64_t)tsc_read() + unscalehrtime(delta);
        wrmsr(IA32_DEADLINE_TSC_MSR, ticks);
}

/*
 * This function will reprogram the timer.
 *
 * When in oneshot mode the argument is the absolute time in future to
 * generate the interrupt at.
 *
 * When in periodic mode, the argument is the interval at which the
 * interrupts should be generated. There is no need to support the periodic
 * mode timer change at this time.
 */
void
apic_timer_reprogram(hrtime_t time)
{
        /*
         * we should be Called from high PIL context (CBE_HIGH_PIL),
         * so kpreempt is disabled.
         */
        apic_timer.apic_timer_reprogram_ops(time);
}

/*
 * This function will enable timer interrupts.
 */
void
apic_timer_enable(void)
{
        /*
         * we should be Called from high PIL context (CBE_HIGH_PIL),
         * so kpreempt is disabled.
         */
        apic_timer.apic_timer_enable_ops();
}

/*
 * This function will disable timer interrupts.
 */
void
apic_timer_disable(void)
{
        /*
         * we should be Called from high PIL context (CBE_HIGH_PIL),
         * so kpreempt is disabled.
         */
        apic_timer.apic_timer_disable_ops();
}

/*
 * Set timer far into the future and return timer
 * current count in nanoseconds.
 */
hrtime_t
apic_timer_stop_count(void)
{
        hrtime_t        ns_val;
        int             enable_val, count_val;

        /*
         * Should be called with interrupts disabled.
         */
        ASSERT(!interrupts_enabled());

        enable_val = apic_reg_ops->apic_read(APIC_LOCAL_TIMER);
        if ((enable_val & AV_MASK) == AV_MASK)
                return ((hrtime_t)-1);  /* timer is disabled */

        count_val = apic_reg_ops->apic_read(APIC_CURR_COUNT);
        ns_val = APIC_TICKS_TO_NSECS(count_val);

        apic_reg_ops->apic_write(APIC_INIT_COUNT, APIC_MAXVAL);

        return (ns_val);
}

/*
 * Reprogram timer after Deep C-State.
 */
void
apic_timer_restart(hrtime_t time)
{
        apic_timer_reprogram(time);
}