// SPDX-License-Identifier: GPL-2.0+

#include <linux/dma-fence.h>

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_vblank.h>

#include "vkms_drv.h"

static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
{
        struct vkms_output *output = container_of(timer, struct vkms_output,
                                                  vblank_hrtimer);
        struct drm_crtc *crtc = &output->crtc;
        struct vkms_crtc_state *state;
        u64 ret_overrun;
        bool ret, fence_cookie;

        fence_cookie = dma_fence_begin_signalling();

        ret_overrun = hrtimer_forward_now(&output->vblank_hrtimer,
                                          output->period_ns);
        if (ret_overrun != 1)
                pr_warn("%s: vblank timer overrun\n", __func__);

        spin_lock(&output->lock);
        ret = drm_crtc_handle_vblank(crtc);
        if (!ret)
                DRM_ERROR("vkms failure on handling vblank");

        state = output->composer_state;
        spin_unlock(&output->lock);

        if (state && output->composer_enabled) {
                u64 frame = drm_crtc_accurate_vblank_count(crtc);

                /* update frame_start only if a queued vkms_composer_worker()
                 * has read the data
                 */
                spin_lock(&output->composer_lock);
                if (!state->crc_pending)
                        state->frame_start = frame;
                else
                        DRM_DEBUG_DRIVER("crc worker falling behind, frame_start: %llu, frame_end: %llu\n",
                                         state->frame_start, frame);
                state->frame_end = frame;
                state->crc_pending = true;
                spin_unlock(&output->composer_lock);

                ret = queue_work(output->composer_workq, &state->composer_work);
                if (!ret)
                        DRM_DEBUG_DRIVER("Composer worker already queued\n");
        }

        dma_fence_end_signalling(fence_cookie);

        return HRTIMER_RESTART;
}

static int vkms_enable_vblank(struct drm_crtc *crtc)
{
        struct drm_device *dev = crtc->dev;
        unsigned int pipe = drm_crtc_index(crtc);
        struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
        struct vkms_output *out = drm_crtc_to_vkms_output(crtc);

        drm_calc_timestamping_constants(crtc, &crtc->mode);

        hrtimer_init(&out->vblank_hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
        out->vblank_hrtimer.function = &vkms_vblank_simulate;
        out->period_ns = ktime_set(0, vblank->framedur_ns);
        hrtimer_start(&out->vblank_hrtimer, out->period_ns, HRTIMER_MODE_REL);

        return 0;
}

static void vkms_disable_vblank(struct drm_crtc *crtc)
{
        struct vkms_output *out = drm_crtc_to_vkms_output(crtc);

        hrtimer_cancel(&out->vblank_hrtimer);
}

static bool vkms_get_vblank_timestamp(struct drm_crtc *crtc,
                                      int *max_error, ktime_t *vblank_time,
                                      bool in_vblank_irq)
{
        struct drm_device *dev = crtc->dev;
        unsigned int pipe = crtc->index;
        struct vkms_device *vkmsdev = drm_device_to_vkms_device(dev);
        struct vkms_output *output = &vkmsdev->output;
        struct drm_vblank_crtc *vblank = &dev->vblank[pipe];

        if (!READ_ONCE(vblank->enabled)) {
                *vblank_time = ktime_get();
                return true;
        }

        *vblank_time = READ_ONCE(output->vblank_hrtimer.node.expires);

        if (WARN_ON(*vblank_time == vblank->time))
                return true;

        /*
         * To prevent races we roll the hrtimer forward before we do any
         * interrupt processing - this is how real hw works (the interrupt is
         * only generated after all the vblank registers are updated) and what
         * the vblank core expects. Therefore we need to always correct the
         * timestampe by one frame.
         */
        *vblank_time -= output->period_ns;

        return true;
}

static struct drm_crtc_state *
vkms_atomic_crtc_duplicate_state(struct drm_crtc *crtc)
{
        struct vkms_crtc_state *vkms_state;

        if (WARN_ON(!crtc->state))
                return NULL;

        vkms_state = kzalloc(sizeof(*vkms_state), GFP_KERNEL);
        if (!vkms_state)
                return NULL;

        __drm_atomic_helper_crtc_duplicate_state(crtc, &vkms_state->base);

        INIT_WORK(&vkms_state->composer_work, vkms_composer_worker);

        return &vkms_state->base;
}

static void vkms_atomic_crtc_destroy_state(struct drm_crtc *crtc,
                                           struct drm_crtc_state *state)
{
        struct vkms_crtc_state *vkms_state = to_vkms_crtc_state(state);

        __drm_atomic_helper_crtc_destroy_state(state);

        WARN_ON(work_pending(&vkms_state->composer_work));
        kfree(vkms_state->active_planes);
        kfree(vkms_state);
}

static void vkms_atomic_crtc_reset(struct drm_crtc *crtc)
{
        struct vkms_crtc_state *vkms_state =
                kzalloc(sizeof(*vkms_state), GFP_KERNEL);

        if (crtc->state)
                vkms_atomic_crtc_destroy_state(crtc, crtc->state);

        __drm_atomic_helper_crtc_reset(crtc, &vkms_state->base);
        if (vkms_state)
                INIT_WORK(&vkms_state->composer_work, vkms_composer_worker);
}

static const struct drm_crtc_funcs vkms_crtc_funcs = {
        .set_config             = drm_atomic_helper_set_config,
        .destroy                = drm_crtc_cleanup,
        .page_flip              = drm_atomic_helper_page_flip,
        .reset                  = vkms_atomic_crtc_reset,
        .atomic_duplicate_state = vkms_atomic_crtc_duplicate_state,
        .atomic_destroy_state   = vkms_atomic_crtc_destroy_state,
        .enable_vblank          = vkms_enable_vblank,
        .disable_vblank         = vkms_disable_vblank,
        .get_vblank_timestamp   = vkms_get_vblank_timestamp,
        .get_crc_sources        = vkms_get_crc_sources,
        .set_crc_source         = vkms_set_crc_source,
        .verify_crc_source      = vkms_verify_crc_source,
};

static int vkms_crtc_atomic_check(struct drm_crtc *crtc,
                                  struct drm_atomic_state *state)
{
        struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state,
                                                                          crtc);
        struct vkms_crtc_state *vkms_state = to_vkms_crtc_state(crtc_state);
        struct drm_plane *plane;
        struct drm_plane_state *plane_state;
        int i = 0, ret;

        if (vkms_state->active_planes)
                return 0;

        ret = drm_atomic_add_affected_planes(crtc_state->state, crtc);
        if (ret < 0)
                return ret;

        drm_for_each_plane_mask(plane, crtc->dev, crtc_state->plane_mask) {
                plane_state = drm_atomic_get_existing_plane_state(crtc_state->state,
                                                                  plane);
                WARN_ON(!plane_state);

                if (!plane_state->visible)
                        continue;

                i++;
        }

        vkms_state->active_planes = kcalloc(i, sizeof(plane), GFP_KERNEL);
        if (!vkms_state->active_planes)
                return -ENOMEM;
        vkms_state->num_active_planes = i;

        i = 0;
        drm_for_each_plane_mask(plane, crtc->dev, crtc_state->plane_mask) {
                plane_state = drm_atomic_get_existing_plane_state(crtc_state->state,
                                                                  plane);

                if (!plane_state->visible)
                        continue;

                vkms_state->active_planes[i++] =
                        to_vkms_plane_state(plane_state);
        }

        return 0;
}

static void vkms_crtc_atomic_enable(struct drm_crtc *crtc,
                                    struct drm_atomic_state *state)
{
        drm_crtc_vblank_on(crtc);
}

static void vkms_crtc_atomic_disable(struct drm_crtc *crtc,
                                     struct drm_atomic_state *state)
{
        drm_crtc_vblank_off(crtc);
}

static void vkms_crtc_atomic_begin(struct drm_crtc *crtc,
                                   struct drm_atomic_state *state)
{
        struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);

        /* This lock is held across the atomic commit to block vblank timer
         * from scheduling vkms_composer_worker until the composer is updated
         */
        spin_lock_irq(&vkms_output->lock);
}

static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,
                                   struct drm_atomic_state *state)
{
        struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);

        if (crtc->state->event) {
                spin_lock(&crtc->dev->event_lock);

                if (drm_crtc_vblank_get(crtc) != 0)
                        drm_crtc_send_vblank_event(crtc, crtc->state->event);
                else
                        drm_crtc_arm_vblank_event(crtc, crtc->state->event);

                spin_unlock(&crtc->dev->event_lock);

                crtc->state->event = NULL;
        }

        vkms_output->composer_state = to_vkms_crtc_state(crtc->state);

        spin_unlock_irq(&vkms_output->lock);
}

static const struct drm_crtc_helper_funcs vkms_crtc_helper_funcs = {
        .atomic_check   = vkms_crtc_atomic_check,
        .atomic_begin   = vkms_crtc_atomic_begin,
        .atomic_flush   = vkms_crtc_atomic_flush,
        .atomic_enable  = vkms_crtc_atomic_enable,
        .atomic_disable = vkms_crtc_atomic_disable,
};

int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
                   struct drm_plane *primary, struct drm_plane *cursor)
{
        struct vkms_output *vkms_out = drm_crtc_to_vkms_output(crtc);
        int ret;

        ret = drm_crtc_init_with_planes(dev, crtc, primary, cursor,
                                        &vkms_crtc_funcs, NULL);
        if (ret) {
                DRM_ERROR("Failed to init CRTC\n");
                return ret;
        }

        drm_crtc_helper_add(crtc, &vkms_crtc_helper_funcs);

        spin_lock_init(&vkms_out->lock);
        spin_lock_init(&vkms_out->composer_lock);

        vkms_out->composer_workq = alloc_ordered_workqueue("vkms_composer", 0);
        if (!vkms_out->composer_workq)
                return -ENOMEM;

        return ret;
}