/*
 * Tegra host1x Syncpoints
 *
 * Copyright (c) 2010-2015, NVIDIA Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/module.h>
#include <linux/device.h>
#include <linux/slab.h>

#include <trace/events/host1x.h>

#include "syncpt.h"
#include "dev.h"
#include "intr.h"
#include "debug.h"

#define SYNCPT_CHECK_PERIOD (2 * HZ)
#define MAX_STUCK_CHECK_COUNT 15

static struct host1x_syncpt_base *
host1x_syncpt_base_request(struct host1x *host)
{
        struct host1x_syncpt_base *bases = host->bases;
        unsigned int i;

        for (i = 0; i < host->info->nb_bases; i++)
                if (!bases[i].requested)
                        break;

        if (i >= host->info->nb_bases)
                return NULL;

        bases[i].requested = true;
        return &bases[i];
}

static void host1x_syncpt_base_free(struct host1x_syncpt_base *base)
{
        if (base)
                base->requested = false;
}

static struct host1x_syncpt *host1x_syncpt_alloc(struct host1x *host,
                                                 struct host1x_client *client,
                                                 unsigned long flags)
{
        struct host1x_syncpt *sp = host->syncpt;
        unsigned int i;
        char *name;

        mutex_lock(&host->syncpt_mutex);

        for (i = 0; i < host->info->nb_pts && sp->name; i++, sp++)
                ;

        if (i >= host->info->nb_pts)
                goto unlock;

        if (flags & HOST1X_SYNCPT_HAS_BASE) {
                sp->base = host1x_syncpt_base_request(host);
                if (!sp->base)
                        goto unlock;
        }

        name = kasprintf(GFP_KERNEL, "%02u-%s", sp->id,
                         client ? dev_name(client->dev) : NULL);
        if (!name)
                goto free_base;

        sp->client = client;
        sp->name = name;

        if (flags & HOST1X_SYNCPT_CLIENT_MANAGED)
                sp->client_managed = true;
        else
                sp->client_managed = false;

        mutex_unlock(&host->syncpt_mutex);
        return sp;

free_base:
        host1x_syncpt_base_free(sp->base);
        sp->base = NULL;
unlock:
        mutex_unlock(&host->syncpt_mutex);
        return NULL;
}

/**
 * host1x_syncpt_id() - retrieve syncpoint ID
 * @sp: host1x syncpoint
 *
 * Given a pointer to a struct host1x_syncpt, retrieves its ID. This ID is
 * often used as a value to program into registers that control how hardware
 * blocks interact with syncpoints.
 */
u32 host1x_syncpt_id(struct host1x_syncpt *sp)
{
        return sp->id;
}
EXPORT_SYMBOL(host1x_syncpt_id);

/**
 * host1x_syncpt_incr_max() - update the value sent to hardware
 * @sp: host1x syncpoint
 * @incrs: number of increments
 */
u32 host1x_syncpt_incr_max(struct host1x_syncpt *sp, u32 incrs)
{
        return (u32)atomic_add_return(incrs, &sp->max_val);
}
EXPORT_SYMBOL(host1x_syncpt_incr_max);

 /*
 * Write cached syncpoint and waitbase values to hardware.
 */
void host1x_syncpt_restore(struct host1x *host)
{
        struct host1x_syncpt *sp_base = host->syncpt;
        unsigned int i;

        for (i = 0; i < host1x_syncpt_nb_pts(host); i++)
                host1x_hw_syncpt_restore(host, sp_base + i);

        for (i = 0; i < host1x_syncpt_nb_bases(host); i++)
                host1x_hw_syncpt_restore_wait_base(host, sp_base + i);

        wmb();
}

/*
 * Update the cached syncpoint and waitbase values by reading them
 * from the registers.
  */
void host1x_syncpt_save(struct host1x *host)
{
        struct host1x_syncpt *sp_base = host->syncpt;
        unsigned int i;

        for (i = 0; i < host1x_syncpt_nb_pts(host); i++) {
                if (host1x_syncpt_client_managed(sp_base + i))
                        host1x_hw_syncpt_load(host, sp_base + i);
                else
                        WARN_ON(!host1x_syncpt_idle(sp_base + i));
        }

        for (i = 0; i < host1x_syncpt_nb_bases(host); i++)
                host1x_hw_syncpt_load_wait_base(host, sp_base + i);
}

/*
 * Updates the cached syncpoint value by reading a new value from the hardware
 * register
 */
u32 host1x_syncpt_load(struct host1x_syncpt *sp)
{
        u32 val;

        val = host1x_hw_syncpt_load(sp->host, sp);
        trace_host1x_syncpt_load_min(sp->id, val);

        return val;
}

/*
 * Get the current syncpoint base
 */
u32 host1x_syncpt_load_wait_base(struct host1x_syncpt *sp)
{
        host1x_hw_syncpt_load_wait_base(sp->host, sp);

        return sp->base_val;
}

/**
 * host1x_syncpt_incr() - increment syncpoint value from CPU, updating cache
 * @sp: host1x syncpoint
 */
int host1x_syncpt_incr(struct host1x_syncpt *sp)
{
        return host1x_hw_syncpt_cpu_incr(sp->host, sp);
}
EXPORT_SYMBOL(host1x_syncpt_incr);

/*
 * Updated sync point form hardware, and returns true if syncpoint is expired,
 * false if we may need to wait
 */
static bool syncpt_load_min_is_expired(struct host1x_syncpt *sp, u32 thresh)
{
        host1x_hw_syncpt_load(sp->host, sp);

        return host1x_syncpt_is_expired(sp, thresh);
}

/**
 * host1x_syncpt_wait() - wait for a syncpoint to reach a given value
 * @sp: host1x syncpoint
 * @thresh: threshold
 * @timeout: maximum time to wait for the syncpoint to reach the given value
 * @value: return location for the syncpoint value
 */
int host1x_syncpt_wait(struct host1x_syncpt *sp, u32 thresh, long timeout,
                       u32 *value)
{
        DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
        void *ref;
        struct host1x_waitlist *waiter;
        int err = 0, check_count = 0;
        u32 val;

        if (value)
                *value = 0;

        /* first check cache */
        if (host1x_syncpt_is_expired(sp, thresh)) {
                if (value)
                        *value = host1x_syncpt_load(sp);

                return 0;
        }

        /* try to read from register */
        val = host1x_hw_syncpt_load(sp->host, sp);
        if (host1x_syncpt_is_expired(sp, thresh)) {
                if (value)
                        *value = val;

                goto done;
        }

        if (!timeout) {
                err = -EAGAIN;
                goto done;
        }

        /* allocate a waiter */
        waiter = kzalloc(sizeof(*waiter), GFP_KERNEL);
        if (!waiter) {
                err = -ENOMEM;
                goto done;
        }

        /* schedule a wakeup when the syncpoint value is reached */
        err = host1x_intr_add_action(sp->host, sp, thresh,
                                     HOST1X_INTR_ACTION_WAKEUP_INTERRUPTIBLE,
                                     &wq, waiter, &ref);
        if (err)
                goto done;

        err = -EAGAIN;
        /* Caller-specified timeout may be impractically low */
        if (timeout < 0)
                timeout = LONG_MAX;

        /* wait for the syncpoint, or timeout, or signal */
        while (timeout) {
                long check = min_t(long, SYNCPT_CHECK_PERIOD, timeout);
                int remain;

                remain = wait_event_interruptible_timeout(wq,
                                syncpt_load_min_is_expired(sp, thresh),
                                check);
                if (remain > 0 || host1x_syncpt_is_expired(sp, thresh)) {
                        if (value)
                                *value = host1x_syncpt_load(sp);

                        err = 0;

                        break;
                }

                if (remain < 0) {
                        err = remain;
                        break;
                }

                timeout -= check;

                if (timeout && check_count <= MAX_STUCK_CHECK_COUNT) {
                        dev_warn(sp->host->dev,
                                "%s: syncpoint id %u (%s) stuck waiting %d, timeout=%ld\n",
                                 current->comm, sp->id, sp->name,
                                 thresh, timeout);

                        host1x_debug_dump_syncpts(sp->host);

                        if (check_count == MAX_STUCK_CHECK_COUNT)
                                host1x_debug_dump(sp->host);

                        check_count++;
                }
        }

        host1x_intr_put_ref(sp->host, sp->id, ref);

done:
        return err;
}
EXPORT_SYMBOL(host1x_syncpt_wait);

/*
 * Returns true if syncpoint is expired, false if we may need to wait
 */
bool host1x_syncpt_is_expired(struct host1x_syncpt *sp, u32 thresh)
{
        u32 current_val;
        u32 future_val;

        smp_rmb();

        current_val = (u32)atomic_read(&sp->min_val);
        future_val = (u32)atomic_read(&sp->max_val);

        /* Note the use of unsigned arithmetic here (mod 1<<32).
         *
         * c = current_val = min_val    = the current value of the syncpoint.
         * t = thresh                   = the value we are checking
         * f = future_val  = max_val    = the value c will reach when all
         *                                outstanding increments have completed.
         *
         * Note that c always chases f until it reaches f.
         *
         * Dtf = (f - t)
         * Dtc = (c - t)
         *
         *  Consider all cases:
         *
         *      A) .....c..t..f.....    Dtf < Dtc       need to wait
         *      B) .....c.....f..t..    Dtf > Dtc       expired
         *      C) ..t..c.....f.....    Dtf > Dtc       expired    (Dct very large)
         *
         *  Any case where f==c: always expired (for any t).    Dtf == Dcf
         *  Any case where t==c: always expired (for any f).    Dtf >= Dtc (because Dtc==0)
         *  Any case where t==f!=c: always wait.                Dtf <  Dtc (because Dtf==0,
         *                                                      Dtc!=0)
         *
         *  Other cases:
         *
         *      A) .....t..f..c.....    Dtf < Dtc       need to wait
         *      A) .....f..c..t.....    Dtf < Dtc       need to wait
         *      A) .....f..t..c.....    Dtf > Dtc       expired
         *
         *   So:
         *         Dtf >= Dtc implies EXPIRED   (return true)
         *         Dtf <  Dtc implies WAIT      (return false)
         *
         * Note: If t is expired then we *cannot* wait on it. We would wait
         * forever (hang the system).
         *
         * Note: do NOT get clever and remove the -thresh from both sides. It
         * is NOT the same.
         *
         * If future valueis zero, we have a client managed sync point. In that
         * case we do a direct comparison.
         */
        if (!host1x_syncpt_client_managed(sp))
                return future_val - thresh >= current_val - thresh;
        else
                return (s32)(current_val - thresh) >= 0;
}

int host1x_syncpt_init(struct host1x *host)
{
        struct host1x_syncpt_base *bases;
        struct host1x_syncpt *syncpt;
        unsigned int i;

        syncpt = devm_kcalloc(host->dev, host->info->nb_pts, sizeof(*syncpt),
                              GFP_KERNEL);
        if (!syncpt)
                return -ENOMEM;

        bases = devm_kcalloc(host->dev, host->info->nb_bases, sizeof(*bases),
                             GFP_KERNEL);
        if (!bases)
                return -ENOMEM;

        for (i = 0; i < host->info->nb_pts; i++) {
                syncpt[i].id = i;
                syncpt[i].host = host;

                /*
                 * Unassign syncpt from channels for purposes of Tegra186
                 * syncpoint protection. This prevents any channel from
                 * accessing it until it is reassigned.
                 */
                host1x_hw_syncpt_assign_to_channel(host, &syncpt[i], NULL);
        }

        for (i = 0; i < host->info->nb_bases; i++)
                bases[i].id = i;

        mutex_init(&host->syncpt_mutex);
        host->syncpt = syncpt;
        host->bases = bases;

        host1x_syncpt_restore(host);
        host1x_hw_syncpt_enable_protection(host);

        /* Allocate sync point to use for clearing waits for expired fences */
        host->nop_sp = host1x_syncpt_alloc(host, NULL, 0);
        if (!host->nop_sp)
                return -ENOMEM;

        return 0;
}

/**
 * host1x_syncpt_request() - request a syncpoint
 * @client: client requesting the syncpoint
 * @flags: flags
 *
 * host1x client drivers can use this function to allocate a syncpoint for
 * subsequent use. A syncpoint returned by this function will be reserved for
 * use by the client exclusively. When no longer using a syncpoint, a host1x
 * client driver needs to release it using host1x_syncpt_free().
 */
struct host1x_syncpt *host1x_syncpt_request(struct host1x_client *client,
                                            unsigned long flags)
{
        struct host1x *host = dev_get_drvdata(client->parent->parent);

        return host1x_syncpt_alloc(host, client, flags);
}
EXPORT_SYMBOL(host1x_syncpt_request);

/**
 * host1x_syncpt_free() - free a requested syncpoint
 * @sp: host1x syncpoint
 *
 * Release a syncpoint previously allocated using host1x_syncpt_request(). A
 * host1x client driver should call this when the syncpoint is no longer in
 * use. Note that client drivers must ensure that the syncpoint doesn't remain
 * under the control of hardware after calling this function, otherwise two
 * clients may end up trying to access the same syncpoint concurrently.
 */
void host1x_syncpt_free(struct host1x_syncpt *sp)
{
        if (!sp)
                return;

        mutex_lock(&sp->host->syncpt_mutex);

        host1x_syncpt_base_free(sp->base);
        kfree(sp->name);
        sp->base = NULL;
        sp->client = NULL;
        sp->name = NULL;
        sp->client_managed = false;

        mutex_unlock(&sp->host->syncpt_mutex);
}
EXPORT_SYMBOL(host1x_syncpt_free);

void host1x_syncpt_deinit(struct host1x *host)
{
        struct host1x_syncpt *sp = host->syncpt;
        unsigned int i;

        for (i = 0; i < host->info->nb_pts; i++, sp++)
                kfree(sp->name);
}

/**
 * host1x_syncpt_read_max() - read maximum syncpoint value
 * @sp: host1x syncpoint
 *
 * The maximum syncpoint value indicates how many operations there are in
 * queue, either in channel or in a software thread.
 */
u32 host1x_syncpt_read_max(struct host1x_syncpt *sp)
{
        smp_rmb();

        return (u32)atomic_read(&sp->max_val);
}
EXPORT_SYMBOL(host1x_syncpt_read_max);

/**
 * host1x_syncpt_read_min() - read minimum syncpoint value
 * @sp: host1x syncpoint
 *
 * The minimum syncpoint value is a shadow of the current sync point value in
 * hardware.
 */
u32 host1x_syncpt_read_min(struct host1x_syncpt *sp)
{
        smp_rmb();

        return (u32)atomic_read(&sp->min_val);
}
EXPORT_SYMBOL(host1x_syncpt_read_min);

/**
 * host1x_syncpt_read() - read the current syncpoint value
 * @sp: host1x syncpoint
 */
u32 host1x_syncpt_read(struct host1x_syncpt *sp)
{
        return host1x_syncpt_load(sp);
}
EXPORT_SYMBOL(host1x_syncpt_read);

unsigned int host1x_syncpt_nb_pts(struct host1x *host)
{
        return host->info->nb_pts;
}

unsigned int host1x_syncpt_nb_bases(struct host1x *host)
{
        return host->info->nb_bases;
}

unsigned int host1x_syncpt_nb_mlocks(struct host1x *host)
{
        return host->info->nb_mlocks;
}

/**
 * host1x_syncpt_get() - obtain a syncpoint by ID
 * @host: host1x controller
 * @id: syncpoint ID
 */
struct host1x_syncpt *host1x_syncpt_get(struct host1x *host, unsigned int id)
{
        if (id >= host->info->nb_pts)
                return NULL;

        return host->syncpt + id;
}
EXPORT_SYMBOL(host1x_syncpt_get);

/**
 * host1x_syncpt_get_base() - obtain the wait base associated with a syncpoint
 * @sp: host1x syncpoint
 */
struct host1x_syncpt_base *host1x_syncpt_get_base(struct host1x_syncpt *sp)
{
        return sp ? sp->base : NULL;
}
EXPORT_SYMBOL(host1x_syncpt_get_base);

/**
 * host1x_syncpt_base_id() - retrieve the ID of a syncpoint wait base
 * @base: host1x syncpoint wait base
 */
u32 host1x_syncpt_base_id(struct host1x_syncpt_base *base)
{
        return base->id;
}
EXPORT_SYMBOL(host1x_syncpt_base_id);