// SPDX-License-Identifier: GPL-2.0 OR MIT

/*
 *  Xen para-virtual DRM device
 *
 * Copyright (C) 2016-2018 EPAM Systems Inc.
 *
 * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
 */

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_drv.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_gem.h>
#include <drm/drm_gem_atomic_helper.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_vblank.h>

#include "xen_drm_front.h"
#include "xen_drm_front_conn.h"
#include "xen_drm_front_kms.h"

/*
 * Timeout in ms to wait for frame done event from the backend:
 * must be a bit more than IO time-out
 */
#define FRAME_DONE_TO_MS        (XEN_DRM_FRONT_WAIT_BACK_MS + 100)

static struct xen_drm_front_drm_pipeline *
to_xen_drm_pipeline(struct drm_simple_display_pipe *pipe)
{
        return container_of(pipe, struct xen_drm_front_drm_pipeline, pipe);
}

static void fb_destroy(struct drm_framebuffer *fb)
{
        struct xen_drm_front_drm_info *drm_info = fb->dev->dev_private;
        int idx;

        if (drm_dev_enter(fb->dev, &idx)) {
                xen_drm_front_fb_detach(drm_info->front_info,
                                        xen_drm_front_fb_to_cookie(fb));
                drm_dev_exit(idx);
        }
        drm_gem_fb_destroy(fb);
}

static const struct drm_framebuffer_funcs fb_funcs = {
        .destroy = fb_destroy,
};

static struct drm_framebuffer *
fb_create(struct drm_device *dev, struct drm_file *filp,
          const struct drm_mode_fb_cmd2 *mode_cmd)
{
        struct xen_drm_front_drm_info *drm_info = dev->dev_private;
        struct drm_framebuffer *fb;
        struct drm_gem_object *gem_obj;
        int ret;

        fb = drm_gem_fb_create_with_funcs(dev, filp, mode_cmd, &fb_funcs);
        if (IS_ERR(fb))
                return fb;

        gem_obj = fb->obj[0];

        ret = xen_drm_front_fb_attach(drm_info->front_info,
                                      xen_drm_front_dbuf_to_cookie(gem_obj),
                                      xen_drm_front_fb_to_cookie(fb),
                                      fb->width, fb->height,
                                      fb->format->format);
        if (ret < 0) {
                DRM_ERROR("Back failed to attach FB %p: %d\n", fb, ret);
                goto fail;
        }

        return fb;

fail:
        drm_gem_fb_destroy(fb);
        return ERR_PTR(ret);
}

static const struct drm_mode_config_funcs mode_config_funcs = {
        .fb_create = fb_create,
        .atomic_check = drm_atomic_helper_check,
        .atomic_commit = drm_atomic_helper_commit,
};

static void send_pending_event(struct xen_drm_front_drm_pipeline *pipeline)
{
        struct drm_crtc *crtc = &pipeline->pipe.crtc;
        struct drm_device *dev = crtc->dev;
        unsigned long flags;

        spin_lock_irqsave(&dev->event_lock, flags);
        if (pipeline->pending_event)
                drm_crtc_send_vblank_event(crtc, pipeline->pending_event);
        pipeline->pending_event = NULL;
        spin_unlock_irqrestore(&dev->event_lock, flags);
}

static void display_enable(struct drm_simple_display_pipe *pipe,
                           struct drm_crtc_state *crtc_state,
                           struct drm_plane_state *plane_state)
{
        struct xen_drm_front_drm_pipeline *pipeline =
                        to_xen_drm_pipeline(pipe);
        struct drm_crtc *crtc = &pipe->crtc;
        struct drm_framebuffer *fb = plane_state->fb;
        int ret, idx;

        if (!drm_dev_enter(pipe->crtc.dev, &idx))
                return;

        ret = xen_drm_front_mode_set(pipeline, crtc->x, crtc->y,
                                     fb->width, fb->height,
                                     fb->format->cpp[0] * 8,
                                     xen_drm_front_fb_to_cookie(fb));

        if (ret) {
                DRM_ERROR("Failed to enable display: %d\n", ret);
                pipeline->conn_connected = false;
        }

        drm_dev_exit(idx);
}

static void display_disable(struct drm_simple_display_pipe *pipe)
{
        struct xen_drm_front_drm_pipeline *pipeline =
                        to_xen_drm_pipeline(pipe);
        int ret = 0, idx;

        if (drm_dev_enter(pipe->crtc.dev, &idx)) {
                ret = xen_drm_front_mode_set(pipeline, 0, 0, 0, 0, 0,
                                             xen_drm_front_fb_to_cookie(NULL));
                drm_dev_exit(idx);
        }
        if (ret)
                DRM_ERROR("Failed to disable display: %d\n", ret);

        /* Make sure we can restart with enabled connector next time */
        pipeline->conn_connected = true;

        /* release stalled event if any */
        send_pending_event(pipeline);
}

void xen_drm_front_kms_on_frame_done(struct xen_drm_front_drm_pipeline *pipeline,
                                     u64 fb_cookie)
{
        /*
         * This runs in interrupt context, e.g. under
         * drm_info->front_info->io_lock, so we cannot call _sync version
         * to cancel the work
         */
        cancel_delayed_work(&pipeline->pflip_to_worker);

        send_pending_event(pipeline);
}

static void pflip_to_worker(struct work_struct *work)
{
        struct delayed_work *delayed_work = to_delayed_work(work);
        struct xen_drm_front_drm_pipeline *pipeline =
                        container_of(delayed_work,
                                     struct xen_drm_front_drm_pipeline,
                                     pflip_to_worker);

        DRM_ERROR("Frame done timed-out, releasing");
        send_pending_event(pipeline);
}

static bool display_send_page_flip(struct drm_simple_display_pipe *pipe,
                                   struct drm_plane_state *old_plane_state)
{
        struct drm_plane_state *plane_state =
                        drm_atomic_get_new_plane_state(old_plane_state->state,
                                                       &pipe->plane);

        /*
         * If old_plane_state->fb is NULL and plane_state->fb is not,
         * then this is an atomic commit which will enable display.
         * If old_plane_state->fb is not NULL and plane_state->fb is,
         * then this is an atomic commit which will disable display.
         * Ignore these and do not send page flip as this framebuffer will be
         * sent to the backend as a part of display_set_config call.
         */
        if (old_plane_state->fb && plane_state->fb) {
                struct xen_drm_front_drm_pipeline *pipeline =
                                to_xen_drm_pipeline(pipe);
                struct xen_drm_front_drm_info *drm_info = pipeline->drm_info;
                int ret;

                schedule_delayed_work(&pipeline->pflip_to_worker,
                                      msecs_to_jiffies(FRAME_DONE_TO_MS));

                ret = xen_drm_front_page_flip(drm_info->front_info,
                                              pipeline->index,
                                              xen_drm_front_fb_to_cookie(plane_state->fb));
                if (ret) {
                        DRM_ERROR("Failed to send page flip request to backend: %d\n", ret);

                        pipeline->conn_connected = false;
                        /*
                         * Report the flip not handled, so pending event is
                         * sent, unblocking user-space.
                         */
                        return false;
                }
                /*
                 * Signal that page flip was handled, pending event will be sent
                 * on frame done event from the backend.
                 */
                return true;
        }

        return false;
}

static int display_check(struct drm_simple_display_pipe *pipe,
                         struct drm_plane_state *plane_state,
                         struct drm_crtc_state *crtc_state)
{
        /*
         * Xen doesn't initialize vblanking via drm_vblank_init(), so
         * DRM helpers assume that it doesn't handle vblanking and start
         * sending out fake VBLANK events automatically.
         *
         * As xen contains it's own logic for sending out VBLANK events
         * in send_pending_event(), disable no_vblank (i.e., the xen
         * driver has vblanking support).
         */
        crtc_state->no_vblank = false;

        return 0;
}

static void display_update(struct drm_simple_display_pipe *pipe,
                           struct drm_plane_state *old_plane_state)
{
        struct xen_drm_front_drm_pipeline *pipeline =
                        to_xen_drm_pipeline(pipe);
        struct drm_crtc *crtc = &pipe->crtc;
        struct drm_pending_vblank_event *event;
        int idx;

        event = crtc->state->event;
        if (event) {
                struct drm_device *dev = crtc->dev;
                unsigned long flags;

                WARN_ON(pipeline->pending_event);

                spin_lock_irqsave(&dev->event_lock, flags);
                crtc->state->event = NULL;

                pipeline->pending_event = event;
                spin_unlock_irqrestore(&dev->event_lock, flags);
        }

        if (!drm_dev_enter(pipe->crtc.dev, &idx)) {
                send_pending_event(pipeline);
                return;
        }

        /*
         * Send page flip request to the backend *after* we have event cached
         * above, so on page flip done event from the backend we can
         * deliver it and there is no race condition between this code and
         * event from the backend.
         * If this is not a page flip, e.g. no flip done event from the backend
         * is expected, then send now.
         */
        if (!display_send_page_flip(pipe, old_plane_state))
                send_pending_event(pipeline);

        drm_dev_exit(idx);
}

static enum drm_mode_status
display_mode_valid(struct drm_simple_display_pipe *pipe,
                   const struct drm_display_mode *mode)
{
        struct xen_drm_front_drm_pipeline *pipeline =
                        container_of(pipe, struct xen_drm_front_drm_pipeline,
                                     pipe);

        if (mode->hdisplay != pipeline->width)
                return MODE_ERROR;

        if (mode->vdisplay != pipeline->height)
                return MODE_ERROR;

        return MODE_OK;
}

static const struct drm_simple_display_pipe_funcs display_funcs = {
        .mode_valid = display_mode_valid,
        .enable = display_enable,
        .disable = display_disable,
        .prepare_fb = drm_gem_simple_display_pipe_prepare_fb,
        .check = display_check,
        .update = display_update,
};

static int display_pipe_init(struct xen_drm_front_drm_info *drm_info,
                             int index, struct xen_drm_front_cfg_connector *cfg,
                             struct xen_drm_front_drm_pipeline *pipeline)
{
        struct drm_device *dev = drm_info->drm_dev;
        const u32 *formats;
        int format_count;
        int ret;

        pipeline->drm_info = drm_info;
        pipeline->index = index;
        pipeline->height = cfg->height;
        pipeline->width = cfg->width;

        INIT_DELAYED_WORK(&pipeline->pflip_to_worker, pflip_to_worker);

        ret = xen_drm_front_conn_init(drm_info, &pipeline->conn);
        if (ret)
                return ret;

        formats = xen_drm_front_conn_get_formats(&format_count);

        return drm_simple_display_pipe_init(dev, &pipeline->pipe,
                                            &display_funcs, formats,
                                            format_count, NULL,
                                            &pipeline->conn);
}

int xen_drm_front_kms_init(struct xen_drm_front_drm_info *drm_info)
{
        struct drm_device *dev = drm_info->drm_dev;
        int i, ret;

        drm_mode_config_init(dev);

        dev->mode_config.min_width = 0;
        dev->mode_config.min_height = 0;
        dev->mode_config.max_width = 4095;
        dev->mode_config.max_height = 2047;
        dev->mode_config.funcs = &mode_config_funcs;

        for (i = 0; i < drm_info->front_info->cfg.num_connectors; i++) {
                struct xen_drm_front_cfg_connector *cfg =
                                &drm_info->front_info->cfg.connectors[i];
                struct xen_drm_front_drm_pipeline *pipeline =
                                &drm_info->pipeline[i];

                ret = display_pipe_init(drm_info, i, cfg, pipeline);
                if (ret) {
                        drm_mode_config_cleanup(dev);
                        return ret;
                }
        }

        drm_mode_config_reset(dev);
        drm_kms_helper_poll_init(dev);
        return 0;
}

void xen_drm_front_kms_fini(struct xen_drm_front_drm_info *drm_info)
{
        int i;

        for (i = 0; i < drm_info->front_info->cfg.num_connectors; i++) {
                struct xen_drm_front_drm_pipeline *pipeline =
                                &drm_info->pipeline[i];

                cancel_delayed_work_sync(&pipeline->pflip_to_worker);

                send_pending_event(pipeline);
        }
}