/*
 * 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_modes.h>
#include <drm/tinydrm/tinydrm.h>

struct tinydrm_connector {
	struct drm_connector base;
	const 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,
	.best_encoder = drm_atomic_helper_best_encoder,
};

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);

	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_fb_cma_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_fb_cma_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;

	mode_copy = devm_kmalloc(drm->dev, sizeof(*mode_copy), GFP_KERNEL);
	if (!mode_copy)
		return -ENOMEM;

	*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);

	ret = drm_simple_display_pipe_init(drm, &tdev->pipe, funcs, formats,
					   format_count, NULL, connector);
	if (ret)
		return ret;

	return 0;
}
EXPORT_SYMBOL(tinydrm_display_pipe_init);