/*
 * Copyright (C) 2014 Red Hat
 * Author: Rob Clark <robdclark@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that 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 "msm_drv.h"
#include "msm_kms.h"
#include "msm_gem.h"
#include "msm_fence.h"

struct msm_commit {
        struct drm_device *dev;
        struct drm_atomic_state *state;
        struct work_struct work;
        uint32_t crtc_mask;
};

static void commit_worker(struct work_struct *work);

/* block until specified crtcs are no longer pending update, and
 * atomically mark them as pending update
 */
static int start_atomic(struct msm_drm_private *priv, uint32_t crtc_mask)
{
        int ret;

        spin_lock(&priv->pending_crtcs_event.lock);
        ret = wait_event_interruptible_locked(priv->pending_crtcs_event,
                        !(priv->pending_crtcs & crtc_mask));
        if (ret == 0) {
                DBG("start: %08x", crtc_mask);
                priv->pending_crtcs |= crtc_mask;
        }
        spin_unlock(&priv->pending_crtcs_event.lock);

        return ret;
}

/* clear specified crtcs (no longer pending update)
 */
static void end_atomic(struct msm_drm_private *priv, uint32_t crtc_mask)
{
        spin_lock(&priv->pending_crtcs_event.lock);
        DBG("end: %08x", crtc_mask);
        priv->pending_crtcs &= ~crtc_mask;
        wake_up_all_locked(&priv->pending_crtcs_event);
        spin_unlock(&priv->pending_crtcs_event.lock);
}

static struct msm_commit *commit_init(struct drm_atomic_state *state)
{
        struct msm_commit *c = kzalloc(sizeof(*c), GFP_KERNEL);

        if (!c)
                return NULL;

        c->dev = state->dev;
        c->state = state;

        INIT_WORK(&c->work, commit_worker);

        return c;
}

static void commit_destroy(struct msm_commit *c)
{
        end_atomic(c->dev->dev_private, c->crtc_mask);
        kfree(c);
}

static void msm_atomic_wait_for_commit_done(struct drm_device *dev,
                struct drm_atomic_state *old_state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct msm_drm_private *priv = old_state->dev->dev_private;
        struct msm_kms *kms = priv->kms;
        int i;

        for_each_crtc_in_state(old_state, crtc, crtc_state, i) {
                if (!crtc->state->enable)
                        continue;

                /* Legacy cursor ioctls are completely unsynced, and userspace
                 * relies on that (by doing tons of cursor updates). */
                if (old_state->legacy_cursor_update)
                        continue;

                kms->funcs->wait_for_crtc_commit_done(kms, crtc);
        }
}

/* The (potentially) asynchronous part of the commit.  At this point
 * nothing can fail short of armageddon.
 */
static void complete_commit(struct msm_commit *c, bool async)
{
        struct drm_atomic_state *state = c->state;
        struct drm_device *dev = state->dev;
        struct msm_drm_private *priv = dev->dev_private;
        struct msm_kms *kms = priv->kms;

        drm_atomic_helper_wait_for_fences(dev, state);

        kms->funcs->prepare_commit(kms, state);

        drm_atomic_helper_commit_modeset_disables(dev, state);

        drm_atomic_helper_commit_planes(dev, state, false);

        drm_atomic_helper_commit_modeset_enables(dev, state);

        /* NOTE: _wait_for_vblanks() only waits for vblank on
         * enabled CRTCs.  So we end up faulting when disabling
         * due to (potentially) unref'ing the outgoing fb's
         * before the vblank when the disable has latched.
         *
         * But if it did wait on disabled (or newly disabled)
         * CRTCs, that would be racy (ie. we could have missed
         * the irq.  We need some way to poll for pipe shut
         * down.  Or just live with occasionally hitting the
         * timeout in the CRTC disable path (which really should
         * not be critical path)
         */

        msm_atomic_wait_for_commit_done(dev, state);

        drm_atomic_helper_cleanup_planes(dev, state);

        kms->funcs->complete_commit(kms, state);

        drm_atomic_state_free(state);

        commit_destroy(c);
}

static void commit_worker(struct work_struct *work)
{
        complete_commit(container_of(work, struct msm_commit, work), true);
}

int msm_atomic_check(struct drm_device *dev,
                     struct drm_atomic_state *state)
{
        int ret;

        /*
         * msm ->atomic_check can update ->mode_changed for pixel format
         * changes, hence must be run before we check the modeset changes.
         */
        ret = drm_atomic_helper_check_planes(dev, state);
        if (ret)
                return ret;

        ret = drm_atomic_helper_check_modeset(dev, state);
        if (ret)
                return ret;

        return ret;
}

/**
 * drm_atomic_helper_commit - commit validated state object
 * @dev: DRM device
 * @state: the driver state object
 * @nonblock: nonblocking commit
 *
 * This function commits a with drm_atomic_helper_check() pre-validated state
 * object. This can still fail when e.g. the framebuffer reservation fails.
 *
 * RETURNS
 * Zero for success or -errno.
 */
int msm_atomic_commit(struct drm_device *dev,
                struct drm_atomic_state *state, bool nonblock)
{
        struct msm_drm_private *priv = dev->dev_private;
        struct msm_commit *c;
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_plane *plane;
        struct drm_plane_state *plane_state;
        int i, ret;

        ret = drm_atomic_helper_prepare_planes(dev, state);
        if (ret)
                return ret;

        c = commit_init(state);
        if (!c) {
                ret = -ENOMEM;
                goto error;
        }

        /*
         * Figure out what crtcs we have:
         */
        for_each_crtc_in_state(state, crtc, crtc_state, i)
                c->crtc_mask |= drm_crtc_mask(crtc);

        /*
         * Figure out what fence to wait for:
         */
        for_each_plane_in_state(state, plane, plane_state, i) {
                if ((plane->state->fb != plane_state->fb) && plane_state->fb) {
                        struct drm_gem_object *obj = msm_framebuffer_bo(plane_state->fb, 0);
                        struct msm_gem_object *msm_obj = to_msm_bo(obj);

                        plane_state->fence = reservation_object_get_excl_rcu(msm_obj->resv);
                }
        }

        /*
         * Wait for pending updates on any of the same crtc's and then
         * mark our set of crtc's as busy:
         */
        ret = start_atomic(dev->dev_private, c->crtc_mask);
        if (ret) {
                kfree(c);
                goto error;
        }

        /*
         * This is the point of no return - everything below never fails except
         * when the hw goes bonghits. Which means we can commit the new state on
         * the software side now.
         */

        drm_atomic_helper_swap_state(state, true);

        /*
         * Everything below can be run asynchronously without the need to grab
         * any modeset locks at all under one conditions: It must be guaranteed
         * that the asynchronous work has either been cancelled (if the driver
         * supports it, which at least requires that the framebuffers get
         * cleaned up with drm_atomic_helper_cleanup_planes()) or completed
         * before the new state gets committed on the software side with
         * drm_atomic_helper_swap_state().
         *
         * This scheme allows new atomic state updates to be prepared and
         * checked in parallel to the asynchronous completion of the previous
         * update. Which is important since compositors need to figure out the
         * composition of the next frame right after having submitted the
         * current layout.
         */

        if (nonblock) {
                queue_work(priv->atomic_wq, &c->work);
                return 0;
        }

        complete_commit(c, false);

        return 0;

error:
        drm_atomic_helper_cleanup_planes(dev, state);
        return ret;
}