/*
 * Tegra host1x Interrupt Management
 *
 * Copyright (c) 2010-2013, 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/clk.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/irq.h>

#include <trace/events/host1x.h>
#include "channel.h"
#include "dev.h"
#include "intr.h"

/* Wait list management */

enum waitlist_state {
        WLS_PENDING,
        WLS_REMOVED,
        WLS_CANCELLED,
        WLS_HANDLED
};

static void waiter_release(struct kref *kref)
{
        kfree(container_of(kref, struct host1x_waitlist, refcount));
}

/*
 * add a waiter to a waiter queue, sorted by threshold
 * returns true if it was added at the head of the queue
 */
static bool add_waiter_to_queue(struct host1x_waitlist *waiter,
                                struct list_head *queue)
{
        struct host1x_waitlist *pos;
        u32 thresh = waiter->thresh;

        list_for_each_entry_reverse(pos, queue, list)
                if ((s32)(pos->thresh - thresh) <= 0) {
                        list_add(&waiter->list, &pos->list);
                        return false;
                }

        list_add(&waiter->list, queue);
        return true;
}

/*
 * run through a waiter queue for a single sync point ID
 * and gather all completed waiters into lists by actions
 */
static void remove_completed_waiters(struct list_head *head, u32 sync,
                        struct list_head completed[HOST1X_INTR_ACTION_COUNT])
{
        struct list_head *dest;
        struct host1x_waitlist *waiter, *next, *prev;

        list_for_each_entry_safe(waiter, next, head, list) {
                if ((s32)(waiter->thresh - sync) > 0)
                        break;

                dest = completed + waiter->action;

                /* consolidate submit cleanups */
                if (waiter->action == HOST1X_INTR_ACTION_SUBMIT_COMPLETE &&
                    !list_empty(dest)) {
                        prev = list_entry(dest->prev,
                                          struct host1x_waitlist, list);
                        if (prev->data == waiter->data) {
                                prev->count++;
                                dest = NULL;
                        }
                }

                /* PENDING->REMOVED or CANCELLED->HANDLED */
                if (atomic_inc_return(&waiter->state) == WLS_HANDLED || !dest) {
                        list_del(&waiter->list);
                        kref_put(&waiter->refcount, waiter_release);
                } else
                        list_move_tail(&waiter->list, dest);
        }
}

static void reset_threshold_interrupt(struct host1x *host,
                                      struct list_head *head,
                                      unsigned int id)
{
        u32 thresh =
                list_first_entry(head, struct host1x_waitlist, list)->thresh;

        host1x_hw_intr_set_syncpt_threshold(host, id, thresh);
        host1x_hw_intr_enable_syncpt_intr(host, id);
}

static void action_submit_complete(struct host1x_waitlist *waiter)
{
        struct host1x_channel *channel = waiter->data;

        host1x_cdma_update(&channel->cdma);

        /*  Add nr_completed to trace */
        trace_host1x_channel_submit_complete(dev_name(channel->dev),
                                             waiter->count, waiter->thresh);

}

static void action_wakeup(struct host1x_waitlist *waiter)
{
        wait_queue_head_t *wq = waiter->data;
        wake_up(wq);
}

static void action_wakeup_interruptible(struct host1x_waitlist *waiter)
{
        wait_queue_head_t *wq = waiter->data;
        wake_up_interruptible(wq);
}

typedef void (*action_handler)(struct host1x_waitlist *waiter);

static action_handler action_handlers[HOST1X_INTR_ACTION_COUNT] = {
        action_submit_complete,
        action_wakeup,
        action_wakeup_interruptible,
};

static void run_handlers(struct list_head completed[HOST1X_INTR_ACTION_COUNT])
{
        struct list_head *head = completed;
        int i;

        for (i = 0; i < HOST1X_INTR_ACTION_COUNT; ++i, ++head) {
                action_handler handler = action_handlers[i];
                struct host1x_waitlist *waiter, *next;

                list_for_each_entry_safe(waiter, next, head, list) {
                        list_del(&waiter->list);
                        handler(waiter);
                        WARN_ON(atomic_xchg(&waiter->state, WLS_HANDLED) !=
                                WLS_REMOVED);
                        kref_put(&waiter->refcount, waiter_release);
                }
        }
}

/*
 * Remove & handle all waiters that have completed for the given syncpt
 */
static int process_wait_list(struct host1x *host,
                             struct host1x_syncpt *syncpt,
                             u32 threshold)
{
        struct list_head completed[HOST1X_INTR_ACTION_COUNT];
        unsigned int i;
        int empty;

        for (i = 0; i < HOST1X_INTR_ACTION_COUNT; ++i)
                INIT_LIST_HEAD(completed + i);

        spin_lock(&syncpt->intr.lock);

        remove_completed_waiters(&syncpt->intr.wait_head, threshold,
                                 completed);

        empty = list_empty(&syncpt->intr.wait_head);
        if (empty)
                host1x_hw_intr_disable_syncpt_intr(host, syncpt->id);
        else
                reset_threshold_interrupt(host, &syncpt->intr.wait_head,
                                          syncpt->id);

        spin_unlock(&syncpt->intr.lock);

        run_handlers(completed);

        return empty;
}

/*
 * Sync point threshold interrupt service thread function
 * Handles sync point threshold triggers, in thread context
 */

static void syncpt_thresh_work(struct work_struct *work)
{
        struct host1x_syncpt_intr *syncpt_intr =
                container_of(work, struct host1x_syncpt_intr, work);
        struct host1x_syncpt *syncpt =
                container_of(syncpt_intr, struct host1x_syncpt, intr);
        unsigned int id = syncpt->id;
        struct host1x *host = syncpt->host;

        (void)process_wait_list(host, syncpt,
                                host1x_syncpt_load(host->syncpt + id));
}

int host1x_intr_add_action(struct host1x *host, u32 id, u32 thresh,
                           enum host1x_intr_action action, void *data,
                           struct host1x_waitlist *waiter, void **ref)
{
        struct host1x_syncpt *syncpt;
        int queue_was_empty;

        if (waiter == NULL) {
                pr_warn("%s: NULL waiter\n", __func__);
                return -EINVAL;
        }

        /* initialize a new waiter */
        INIT_LIST_HEAD(&waiter->list);
        kref_init(&waiter->refcount);
        if (ref)
                kref_get(&waiter->refcount);
        waiter->thresh = thresh;
        waiter->action = action;
        atomic_set(&waiter->state, WLS_PENDING);
        waiter->data = data;
        waiter->count = 1;

        syncpt = host->syncpt + id;

        spin_lock(&syncpt->intr.lock);

        queue_was_empty = list_empty(&syncpt->intr.wait_head);

        if (add_waiter_to_queue(waiter, &syncpt->intr.wait_head)) {
                /* added at head of list - new threshold value */
                host1x_hw_intr_set_syncpt_threshold(host, id, thresh);

                /* added as first waiter - enable interrupt */
                if (queue_was_empty)
                        host1x_hw_intr_enable_syncpt_intr(host, id);
        }

        spin_unlock(&syncpt->intr.lock);

        if (ref)
                *ref = waiter;
        return 0;
}

void host1x_intr_put_ref(struct host1x *host, u32 id, void *ref)
{
        struct host1x_waitlist *waiter = ref;
        struct host1x_syncpt *syncpt;

        while (atomic_cmpxchg(&waiter->state, WLS_PENDING, WLS_CANCELLED) ==
               WLS_REMOVED)
                schedule();

        syncpt = host->syncpt + id;
        (void)process_wait_list(host, syncpt,
                                host1x_syncpt_load(host->syncpt + id));

        kref_put(&waiter->refcount, waiter_release);
}

int host1x_intr_init(struct host1x *host, unsigned int irq_sync)
{
        unsigned int id;
        u32 nb_pts = host1x_syncpt_nb_pts(host);

        mutex_init(&host->intr_mutex);
        host->intr_syncpt_irq = irq_sync;
        host->intr_wq = create_workqueue("host_syncpt");
        if (!host->intr_wq)
                return -ENOMEM;

        for (id = 0; id < nb_pts; ++id) {
                struct host1x_syncpt *syncpt = host->syncpt + id;

                spin_lock_init(&syncpt->intr.lock);
                INIT_LIST_HEAD(&syncpt->intr.wait_head);
                snprintf(syncpt->intr.thresh_irq_name,
                         sizeof(syncpt->intr.thresh_irq_name),
                         "host1x_sp_%02d", id);
        }

        host1x_intr_start(host);

        return 0;
}

void host1x_intr_deinit(struct host1x *host)
{
        host1x_intr_stop(host);
        destroy_workqueue(host->intr_wq);
}

void host1x_intr_start(struct host1x *host)
{
        u32 hz = clk_get_rate(host->clk);
        int err;

        mutex_lock(&host->intr_mutex);
        err = host1x_hw_intr_init_host_sync(host, DIV_ROUND_UP(hz, 1000000),
                                            syncpt_thresh_work);
        if (err) {
                mutex_unlock(&host->intr_mutex);
                return;
        }
        mutex_unlock(&host->intr_mutex);
}

void host1x_intr_stop(struct host1x *host)
{
        unsigned int id;
        struct host1x_syncpt *syncpt = host->syncpt;
        u32 nb_pts = host1x_syncpt_nb_pts(host);

        mutex_lock(&host->intr_mutex);

        host1x_hw_intr_disable_all_syncpt_intrs(host);

        for (id = 0; id < nb_pts; ++id) {
                struct host1x_waitlist *waiter, *next;

                list_for_each_entry_safe(waiter, next,
                        &syncpt[id].intr.wait_head, list) {
                        if (atomic_cmpxchg(&waiter->state,
                            WLS_CANCELLED, WLS_HANDLED) == WLS_CANCELLED) {
                                list_del(&waiter->list);
                                kref_put(&waiter->refcount, waiter_release);
                        }
                }

                if (!list_empty(&syncpt[id].intr.wait_head)) {
                        /* output diagnostics */
                        mutex_unlock(&host->intr_mutex);
                        pr_warn("%s cannot stop syncpt intr id=%d\n",
                                __func__, id);
                        return;
                }
        }

        host1x_hw_intr_free_syncpt_irq(host);

        mutex_unlock(&host->intr_mutex);
}