/*-
 * Copyright (c) 2000 Michael Smith
 * Copyright (c) 2000 BSDi
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/sys/dev/acpica/Osd/OsdSynch.c,v 1.21 2004/05/05 20:07:52 njl Exp $
 */

/*
 * Mutual Exclusion and Synchronisation
 */

#include "acpi.h"
#include "accommon.h"

#include "opt_acpi.h"

#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/malloc.h>
#include <sys/sysctl.h>
#include <sys/lock.h>
#include <sys/thread.h>
#include <sys/thread2.h>
#include <sys/spinlock2.h>

#include <dev/acpica/acpivar.h>

#define _COMPONENT      ACPI_OS_SERVICES
ACPI_MODULE_NAME("SYNCH")

MALLOC_DEFINE(M_ACPISEM, "acpisem", "ACPI semaphore");

#define AS_LOCK(as)             spin_lock(&(as)->as_spin)
#define AS_UNLOCK(as)           spin_unlock(&(as)->as_spin)
#define AS_LOCK_DECL

/*
 * Simple counting semaphore implemented using a mutex.  (Subsequently used
 * in the OSI code to implement a mutex.  Go figure.)
 */
struct acpi_semaphore {
    struct      spinlock as_spin;
    UINT32      as_units;
    UINT32      as_maxunits;
    UINT32      as_pendings;
    UINT32      as_resetting;
    UINT32      as_timeouts;
};

#ifndef ACPI_SEMAPHORES_MAX_PENDING
#define ACPI_SEMAPHORES_MAX_PENDING     0x1FFFFFFF
#endif
static int      acpi_semaphore_debug = 0;
TUNABLE_INT("debug.acpi_semaphore_debug", &acpi_semaphore_debug);
SYSCTL_INT(_debug_acpi, OID_AUTO, semaphore_debug, CTLFLAG_RW,
           &acpi_semaphore_debug, 0, "Enable ACPI semaphore debug messages");

ACPI_STATUS
AcpiOsCreateSemaphore(UINT32 MaxUnits, UINT32 InitialUnits,
    ACPI_HANDLE *OutHandle)
{
    struct acpi_semaphore       *as;

    ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);

    if (OutHandle == NULL)
        return_ACPI_STATUS (AE_BAD_PARAMETER);
    if (InitialUnits > MaxUnits)
        return_ACPI_STATUS (AE_BAD_PARAMETER);

    as = kmalloc(sizeof(*as), M_ACPISEM, M_INTWAIT | M_ZERO);

    spin_init(&as->as_spin, "AcpiOsSem");
    as->as_units = InitialUnits;
    as->as_maxunits = MaxUnits;
    as->as_pendings = as->as_resetting = as->as_timeouts = 0;

    ACPI_DEBUG_PRINT((ACPI_DB_MUTEX,
        "created semaphore %p max %d, initial %d\n", 
        as, InitialUnits, MaxUnits));

    *OutHandle = (ACPI_HANDLE)as;

    return_ACPI_STATUS (AE_OK);
}

ACPI_STATUS
AcpiOsDeleteSemaphore(ACPI_HANDLE Handle)
{
    struct acpi_semaphore *as = (struct acpi_semaphore *)Handle;

    ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);

    ACPI_DEBUG_PRINT((ACPI_DB_MUTEX, "destroyed semaphore %p\n", as));
    spin_uninit(&as->as_spin);
    kfree(as, M_ACPISEM);

    return_ACPI_STATUS (AE_OK);
}

ACPI_STATUS
AcpiOsWaitSemaphore(ACPI_HANDLE Handle, UINT32 Units, UINT16 Timeout)
{
    ACPI_STATUS                 result;
    struct acpi_semaphore       *as = (struct acpi_semaphore *)Handle;
    int                         rv, tmo;
    struct timeval              timeouttv, currenttv, timelefttv;
    AS_LOCK_DECL;

    ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);

    if (as == NULL)
        return_ACPI_STATUS (AE_BAD_PARAMETER);

    if (cold)
        return_ACPI_STATUS (AE_OK);

#if 0
    if (as->as_units < Units && as->as_timeouts > 10) {
        kprintf("%s: semaphore %p too many timeouts, resetting\n", __func__, as);
        AS_LOCK(as);
        as->as_units = as->as_maxunits;
        if (as->as_pendings)
            as->as_resetting = 1;
        as->as_timeouts = 0;
        wakeup(as);
        AS_UNLOCK(as);
        return_ACPI_STATUS (AE_TIME);
    }

    if (as->as_resetting)
        return_ACPI_STATUS (AE_TIME);
#endif

    /* a timeout of ACPI_WAIT_FOREVER means "forever" */
    if (Timeout == ACPI_WAIT_FOREVER) {
        tmo = 0;
        timeouttv.tv_sec = ((0xffff/1000) + 1); /* cf. ACPI spec */
        timeouttv.tv_usec = 0;
    } else {
        /* compute timeout using microseconds per tick */
        tmo = (Timeout * 1000) / (1000000 / hz);
        if (tmo <= 0)
            tmo = 1;
        timeouttv.tv_sec  = Timeout / 1000;
        timeouttv.tv_usec = (Timeout % 1000) * 1000;
    }

    /* calculate timeout value in timeval */
    getmicrouptime(&currenttv);
    timevaladd(&timeouttv, &currenttv);

    AS_LOCK(as);
    ACPI_DEBUG_PRINT((ACPI_DB_MUTEX,
        "get %d units from semaphore %p (has %d), timeout %d\n",
        Units, as, as->as_units, Timeout));
    for (;;) {
        if (as->as_maxunits == ACPI_NO_UNIT_LIMIT) {
            result = AE_OK;
            break;
        }
        if (as->as_units >= Units) {
            as->as_units -= Units;
            result = AE_OK;
            break;
        }

        /* limit number of pending treads */
        if (as->as_pendings >= ACPI_SEMAPHORES_MAX_PENDING) {
            result = AE_TIME;
            break;
        }

        /* if timeout values of zero is specified, return immediately */
        if (Timeout == 0) {
            result = AE_TIME;
            break;
        }

        ACPI_DEBUG_PRINT((ACPI_DB_MUTEX,
            "semaphore blocked, calling ssleep(%p, %p, %d, \"acsem\", %d)\n",
            as, &as->as_spin, PCATCH, tmo));

        as->as_pendings++;

        if (acpi_semaphore_debug) {
            kprintf("%s: Sleep %jd, pending %jd, semaphore %p, thread %#jx\n",
                __func__, (intmax_t)Timeout,
                (intmax_t)as->as_pendings, as,
                (uintmax_t)AcpiOsGetThreadId());
        }

        rv = ssleep(as, &as->as_spin, PCATCH, "acsem", tmo);

        as->as_pendings--;

#if 0
        if (as->as_resetting) {
            /* semaphore reset, return immediately */
            if (as->as_pendings == 0) {
                as->as_resetting = 0;
            }
            result = AE_TIME;
            break;
        }
#endif

        ACPI_DEBUG_PRINT((ACPI_DB_MUTEX, "ssleep(%d) returned %d\n", tmo, rv));
        if (rv == EWOULDBLOCK) {
            result = AE_TIME;
            break;
        }

        /* check if we already awaited enough */
        timelefttv = timeouttv;
        getmicrouptime(&currenttv);
        timevalsub(&timelefttv, &currenttv);
        if (timelefttv.tv_sec < 0) {
            ACPI_DEBUG_PRINT((ACPI_DB_MUTEX, "await semaphore %p timeout\n",
                as));
            result = AE_TIME;
            break;
        }

        /* adjust timeout for the next sleep */
        tmo = (timelefttv.tv_sec * 1000000 + timelefttv.tv_usec) /
            (1000000 / hz);
        if (tmo <= 0)
            tmo = 1;

        if (acpi_semaphore_debug) {
            kprintf("%s: Wakeup timeleft(%ju, %ju), tmo %ju, sem %p, thread %#jx\n",
                __func__,
                (intmax_t)timelefttv.tv_sec, (intmax_t)timelefttv.tv_usec,
                (intmax_t)tmo, as, (uintmax_t)AcpiOsGetThreadId());
        }
    }

    if (acpi_semaphore_debug) {
        if (result == AE_TIME && Timeout > 0) {
            kprintf("%s: Timeout %d, pending %d, semaphore %p\n",
                __func__, Timeout, as->as_pendings, as);
        }
        if (ACPI_SUCCESS(result) &&
            (as->as_timeouts > 0 || as->as_pendings > 0))
        {
            kprintf("%s: Acquire %d, units %d, pending %d, sem %p, thread %#jx\n",
                __func__, Units, as->as_units, as->as_pendings, as,
                (uintmax_t)AcpiOsGetThreadId());
        }
    }

    if (result == AE_TIME)
        as->as_timeouts++;
    else
        as->as_timeouts = 0;

    AS_UNLOCK(as);
    return_ACPI_STATUS (result);
}

ACPI_STATUS
AcpiOsSignalSemaphore(ACPI_HANDLE Handle, UINT32 Units)
{
    struct acpi_semaphore       *as = (struct acpi_semaphore *)Handle;
    AS_LOCK_DECL;

    ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);

    if (as == NULL)
        return_ACPI_STATUS(AE_BAD_PARAMETER);

    AS_LOCK(as);
    ACPI_DEBUG_PRINT((ACPI_DB_MUTEX,
        "return %d units to semaphore %p (has %d)\n",
        Units, as, as->as_units));
    if (as->as_maxunits != ACPI_NO_UNIT_LIMIT) {
        as->as_units += Units;
        if (as->as_units > as->as_maxunits)
            as->as_units = as->as_maxunits;
    }

    if (acpi_semaphore_debug && (as->as_timeouts > 0 || as->as_pendings > 0)) {
        kprintf("%s: Release %d, units %d, pending %d, semaphore %p, thread %#jx\n",
            __func__, Units, as->as_units, as->as_pendings, as,
            (uintmax_t)AcpiOsGetThreadId());
    }

    wakeup(as);
    AS_UNLOCK(as);

    return_ACPI_STATUS (AE_OK);
}

/*
 * This represents a bit of a problem, it looks like the ACPI contrib
 * code holds Os locks across potentially blocking system calls.  So
 * we can't safely use spinlocks in all situations.  But any use-cases
 * from the idle thread have to use spinlocks.
 *
 * For now use the spinlock for idlethread operation and the lockmgr lock
 * otherwise.  The only thing the idlethread can issue ACPI-wise is related
 * to cpu low power modes, hopefully this will not interfere with ACPI
 * operations on other cpus on other threads.
 */
struct acpi_spinlock {
    struct lock lock;
    struct spinlock slock;
#ifdef ACPI_DEBUG_LOCKS
    thread_t    owner;
    const char *func;
    int line;
#endif
};

ACPI_STATUS
AcpiOsCreateLock(ACPI_SPINLOCK *OutHandle)
{
    ACPI_SPINLOCK spin;

    if (OutHandle == NULL)
        return (AE_BAD_PARAMETER);
    spin = kmalloc(sizeof(*spin), M_ACPISEM, M_INTWAIT|M_ZERO);
    spin_init(&spin->slock, "AcpiOsLock");
    lockinit(&spin->lock, "AcpiOsLock", 0, 0);
#ifdef ACPI_DEBUG_LOCKS
    spin->owner = NULL;
    spin->func = "";
    spin->line = 0;
#endif
    *OutHandle = spin;
    return (AE_OK);
}

void
AcpiOsDeleteLock (ACPI_SPINLOCK Spin)
{
    if (Spin == NULL)
        return;
    spin_uninit(&Spin->slock);
    lockuninit(&Spin->lock);
    kfree(Spin, M_ACPISEM);
}

/*
 * OS-dependent locking primitives.  These routines should be able to be
 * called from an interrupt-handler or cpu_idle thread.
 *
 * NB: some of ACPICA functions with locking flags, say AcpiSetRegister(),
 * are changed to unconditionally call AcpiOsAcquireLock/AcpiOsReleaseLock.
 */
ACPI_CPU_FLAGS
#ifdef ACPI_DEBUG_LOCKS
_AcpiOsAcquireLock (ACPI_SPINLOCK Spin, const char *func, int line)
#else
AcpiOsAcquireLock (ACPI_SPINLOCK Spin)
#endif
{
    globaldata_t gd = mycpu;

    if (gd->gd_curthread == &gd->gd_idlethread) {
        spin_lock(&Spin->slock);
    } else {
        lockmgr(&Spin->lock, LK_EXCLUSIVE);
        crit_enter();
    }

#ifdef ACPI_DEBUG_LOCKS
    if (Spin->owner) {
        kprintf("%p(%s:%d): acpi_spinlock %p already held by %p(%s:%d)\n",
                curthread, func, line, Spin, Spin->owner, Spin->func,
                Spin->line);
        print_backtrace(-1);
    } else {
        Spin->owner = curthread;
        Spin->func = func;
        Spin->line = line;
    }
#endif
    return(0);
}

void
AcpiOsReleaseLock (ACPI_SPINLOCK Spin, ACPI_CPU_FLAGS Flags)
{
#ifdef ACPI_DEBUG_LOCKS
    if (Flags) {
        if (Spin->owner != NULL) {
            kprintf("%p: acpi_spinlock %p is unexectedly held by %p(%s:%d)\n",
                    curthread, Spin, Spin->owner, Spin->func, Spin->line);
            print_backtrace(-1);
        } else
            return;
    }
    Spin->owner = NULL;
    Spin->func = "";
    Spin->line = 0;
#endif
    globaldata_t gd = mycpu;

    if (gd->gd_curthread == &gd->gd_idlethread) {
        spin_unlock(&Spin->slock);
    } else {
        crit_exit();
        lockmgr(&Spin->lock, LK_RELEASE);
    }
}

/* Section 5.2.9.1:  global lock acquire/release functions */
#define GL_ACQUIRED     (-1)
#define GL_BUSY         0
#define GL_BIT_PENDING  0x1
#define GL_BIT_OWNED    0x2
#define GL_BIT_MASK     (GL_BIT_PENDING | GL_BIT_OWNED)

/*
 * Acquire the global lock.  If busy, set the pending bit.  The caller
 * will wait for notification from the BIOS that the lock is available
 * and then attempt to acquire it again.
 */
int
acpi_acquire_global_lock(uint32_t *lock)
{
        uint32_t new, old;

        do {
                old = *lock;
                new = ((old & ~GL_BIT_MASK) | GL_BIT_OWNED) |
                        ((old >> 1) & GL_BIT_PENDING);
        } while (atomic_cmpset_int(lock, old, new) == 0);

        return ((new < GL_BIT_MASK) ? GL_ACQUIRED : GL_BUSY);
}

/*
 * Release the global lock, returning whether there is a waiter pending.
 * If the BIOS set the pending bit, OSPM must notify the BIOS when it
 * releases the lock.
 */
int
acpi_release_global_lock(uint32_t *lock)
{
        uint32_t new, old;

        do {
                old = *lock;
                new = old & ~GL_BIT_MASK;
        } while (atomic_cmpset_int(lock, old, new) == 0);

        return (old & GL_BIT_PENDING);
}