/*
 * Copyright (C) 2016 Noralf Trønnes
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <drm/drm_atomic_helper.h>
#include <drm/drm_crtc_helper.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_modes.h>
#include <drm/tinydrm/tinydrm.h>

struct tinydrm_connector {
        struct drm_connector base;
        struct drm_display_mode mode;
};

static inline struct tinydrm_connector *
to_tinydrm_connector(struct drm_connector *connector)
{
        return container_of(connector, struct tinydrm_connector, base);
}

static int tinydrm_connector_get_modes(struct drm_connector *connector)
{
        struct tinydrm_connector *tconn = to_tinydrm_connector(connector);
        struct drm_display_mode *mode;

        mode = drm_mode_duplicate(connector->dev, &tconn->mode);
        if (!mode) {
                DRM_ERROR("Failed to duplicate mode\n");
                return 0;
        }

        if (mode->name[0] == '\0')
                drm_mode_set_name(mode);

        mode->type |= DRM_MODE_TYPE_PREFERRED;
        drm_mode_probed_add(connector, mode);

        if (mode->width_mm) {
                connector->display_info.width_mm = mode->width_mm;
                connector->display_info.height_mm = mode->height_mm;
        }

        return 1;
}

static const struct drm_connector_helper_funcs tinydrm_connector_hfuncs = {
        .get_modes = tinydrm_connector_get_modes,
};

static enum drm_connector_status
tinydrm_connector_detect(struct drm_connector *connector, bool force)
{
        if (drm_dev_is_unplugged(connector->dev))
                return connector_status_disconnected;

        return connector->status;
}

static void tinydrm_connector_destroy(struct drm_connector *connector)
{
        struct tinydrm_connector *tconn = to_tinydrm_connector(connector);

        drm_connector_cleanup(connector);
        kfree(tconn);
}

static const struct drm_connector_funcs tinydrm_connector_funcs = {
        .reset = drm_atomic_helper_connector_reset,
        .detect = tinydrm_connector_detect,
        .fill_modes = drm_helper_probe_single_connector_modes,
        .destroy = tinydrm_connector_destroy,
        .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
        .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
};

struct drm_connector *
tinydrm_connector_create(struct drm_device *drm,
                         const struct drm_display_mode *mode,
                         int connector_type)
{
        struct tinydrm_connector *tconn;
        struct drm_connector *connector;
        int ret;

        tconn = kzalloc(sizeof(*tconn), GFP_KERNEL);
        if (!tconn)
                return ERR_PTR(-ENOMEM);

        drm_mode_copy(&tconn->mode, mode);
        connector = &tconn->base;

        drm_connector_helper_add(connector, &tinydrm_connector_hfuncs);
        ret = drm_connector_init(drm, connector, &tinydrm_connector_funcs,
                                 connector_type);
        if (ret) {
                kfree(tconn);
                return ERR_PTR(ret);
        }

        connector->status = connector_status_connected;

        return connector;
}

/**
 * tinydrm_display_pipe_update - Display pipe update helper
 * @pipe: Simple display pipe
 * @old_state: Old plane state
 *
 * This function does a full framebuffer flush if the plane framebuffer
 * has changed. It also handles vblank events. Drivers can use this as their
 * &drm_simple_display_pipe_funcs->update callback.
 */
void tinydrm_display_pipe_update(struct drm_simple_display_pipe *pipe,
                                 struct drm_plane_state *old_state)
{
        struct tinydrm_device *tdev = pipe_to_tinydrm(pipe);
        struct drm_framebuffer *fb = pipe->plane.state->fb;
        struct drm_crtc *crtc = &tdev->pipe.crtc;

        if (fb && (fb != old_state->fb)) {
                pipe->plane.fb = fb;
                if (fb->funcs->dirty)
                        fb->funcs->dirty(fb, NULL, 0, 0, NULL, 0);
        }

        if (crtc->state->event) {
                spin_lock_irq(&crtc->dev->event_lock);
                drm_crtc_send_vblank_event(crtc, crtc->state->event);
                spin_unlock_irq(&crtc->dev->event_lock);
                crtc->state->event = NULL;
        }
}
EXPORT_SYMBOL(tinydrm_display_pipe_update);

/**
 * tinydrm_display_pipe_prepare_fb - Display pipe prepare_fb helper
 * @pipe: Simple display pipe
 * @plane_state: Plane state
 *
 * This function uses drm_gem_fb_prepare_fb() to check if the plane FB has an
 * dma-buf attached, extracts the exclusive fence and attaches it to plane
 * state for the atomic helper to wait on. Drivers can use this as their
 * &drm_simple_display_pipe_funcs->prepare_fb callback.
 */
int tinydrm_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
                                    struct drm_plane_state *plane_state)
{
        return drm_gem_fb_prepare_fb(&pipe->plane, plane_state);
}
EXPORT_SYMBOL(tinydrm_display_pipe_prepare_fb);

static int tinydrm_rotate_mode(struct drm_display_mode *mode,
                               unsigned int rotation)
{
        if (rotation == 0 || rotation == 180) {
                return 0;
        } else if (rotation == 90 || rotation == 270) {
                swap(mode->hdisplay, mode->vdisplay);
                swap(mode->hsync_start, mode->vsync_start);
                swap(mode->hsync_end, mode->vsync_end);
                swap(mode->htotal, mode->vtotal);
                swap(mode->width_mm, mode->height_mm);
                return 0;
        } else {
                return -EINVAL;
        }
}

/**
 * tinydrm_display_pipe_init - Initialize display pipe
 * @tdev: tinydrm device
 * @funcs: Display pipe functions
 * @connector_type: Connector type
 * @formats: Array of supported formats (DRM_FORMAT\_\*)
 * @format_count: Number of elements in @formats
 * @mode: Supported mode
 * @rotation: Initial @mode rotation in degrees Counter Clock Wise
 *
 * This function sets up a &drm_simple_display_pipe with a &drm_connector that
 * has one fixed &drm_display_mode which is rotated according to @rotation.
 *
 * Returns:
 * Zero on success, negative error code on failure.
 */
int
tinydrm_display_pipe_init(struct tinydrm_device *tdev,
                          const struct drm_simple_display_pipe_funcs *funcs,
                          int connector_type,
                          const uint32_t *formats,
                          unsigned int format_count,
                          const struct drm_display_mode *mode,
                          unsigned int rotation)
{
        struct drm_device *drm = tdev->drm;
        struct drm_display_mode mode_copy;
        struct drm_connector *connector;
        int ret;

        drm_mode_copy(&mode_copy, mode);
        ret = tinydrm_rotate_mode(&mode_copy, rotation);
        if (ret) {
                DRM_ERROR("Illegal rotation value %u\n", rotation);
                return -EINVAL;
        }

        drm->mode_config.min_width = mode_copy.hdisplay;
        drm->mode_config.max_width = mode_copy.hdisplay;
        drm->mode_config.min_height = mode_copy.vdisplay;
        drm->mode_config.max_height = mode_copy.vdisplay;

        connector = tinydrm_connector_create(drm, &mode_copy, connector_type);
        if (IS_ERR(connector))
                return PTR_ERR(connector);

        return drm_simple_display_pipe_init(drm, &tdev->pipe, funcs, formats,
                                            format_count, NULL, connector);
}
EXPORT_SYMBOL(tinydrm_display_pipe_init);