/*
 * Copyright (C) 2014 Intel Corporation
 *
 * DRM universal plane helper functions
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/list.h>

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_atomic_uapi.h>
#include <drm/drm_crtc_helper.h>
#include <drm/drm_device.h>
#include <drm/drm_encoder.h>
#include <drm/drm_plane_helper.h>
#include <drm/drm_rect.h>

#define SUBPIXEL_MASK 0xffff

/**
 * DOC: overview
 *
 * This helper library has two parts. The first part has support to implement
 * primary plane support on top of the normal CRTC configuration interface.
 * Since the legacy &drm_mode_config_funcs.set_config interface ties the primary
 * plane together with the CRTC state this does not allow userspace to disable
 * the primary plane itself. The default primary plane only expose XRBG8888 and
 * ARGB8888 as valid pixel formats for the attached framebuffer.
 *
 * Drivers are highly recommended to implement proper support for primary
 * planes, and newly merged drivers must not rely upon these transitional
 * helpers.
 *
 * The second part also implements transitional helpers which allow drivers to
 * gradually switch to the atomic helper infrastructure for plane updates. Once
 * that switch is complete drivers shouldn't use these any longer, instead using
 * the proper legacy implementations for update and disable plane hooks provided
 * by the atomic helpers.
 *
 * Again drivers are strongly urged to switch to the new interfaces.
 *
 * The plane helpers share the function table structures with other helpers,
 * specifically also the atomic helpers. See &struct drm_plane_helper_funcs for
 * the details.
 */

/*
 * Returns the connectors currently associated with a CRTC.  This function
 * should be called twice:  once with a NULL connector list to retrieve
 * the list size, and once with the properly allocated list to be filled in.
 */
static int get_connectors_for_crtc(struct drm_crtc *crtc,
                                   struct drm_connector **connector_list,
                                   int num_connectors)
{
        struct drm_device *dev = crtc->dev;
        struct drm_connector *connector;
        struct drm_connector_list_iter conn_iter;
        int count = 0;

        /*
         * Note: Once we change the plane hooks to more fine-grained locking we
         * need to grab the connection_mutex here to be able to make these
         * checks.
         */
        WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));

        drm_connector_list_iter_begin(dev, &conn_iter);
        drm_for_each_connector_iter(connector, &conn_iter) {
                if (connector->encoder && connector->encoder->crtc == crtc) {
                        if (connector_list != NULL && count < num_connectors)
                                *(connector_list++) = connector;

                        count++;
                }
        }
        drm_connector_list_iter_end(&conn_iter);

        return count;
}

static int drm_plane_helper_check_update(struct drm_plane *plane,
                                         struct drm_crtc *crtc,
                                         struct drm_framebuffer *fb,
                                         struct drm_rect *src,
                                         struct drm_rect *dst,
                                         unsigned int rotation,
                                         int min_scale,
                                         int max_scale,
                                         bool can_position,
                                         bool can_update_disabled,
                                         bool *visible)
{
        struct drm_plane_state plane_state = {
                .plane = plane,
                .crtc = crtc,
                .fb = fb,
                .src_x = src->x1,
                .src_y = src->y1,
                .src_w = drm_rect_width(src),
                .src_h = drm_rect_height(src),
                .crtc_x = dst->x1,
                .crtc_y = dst->y1,
                .crtc_w = drm_rect_width(dst),
                .crtc_h = drm_rect_height(dst),
                .rotation = rotation,
                .visible = *visible,
        };
        struct drm_crtc_state crtc_state = {
                .crtc = crtc,
                .enable = crtc->enabled,
                .mode = crtc->mode,
        };
        int ret;

        ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
                                                  min_scale, max_scale,
                                                  can_position,
                                                  can_update_disabled);
        if (ret)
                return ret;

        *src = plane_state.src;
        *dst = plane_state.dst;
        *visible = plane_state.visible;

        return 0;
}

static int drm_primary_helper_update(struct drm_plane *plane, struct drm_crtc *crtc,
                                     struct drm_framebuffer *fb,
                                     int crtc_x, int crtc_y,
                                     unsigned int crtc_w, unsigned int crtc_h,
                                     uint32_t src_x, uint32_t src_y,
                                     uint32_t src_w, uint32_t src_h,
                                     struct drm_modeset_acquire_ctx *ctx)
{
        struct drm_mode_set set = {
                .crtc = crtc,
                .fb = fb,
                .mode = &crtc->mode,
                .x = src_x >> 16,
                .y = src_y >> 16,
        };
        struct drm_rect src = {
                .x1 = src_x,
                .y1 = src_y,
                .x2 = src_x + src_w,
                .y2 = src_y + src_h,
        };
        struct drm_rect dest = {
                .x1 = crtc_x,
                .y1 = crtc_y,
                .x2 = crtc_x + crtc_w,
                .y2 = crtc_y + crtc_h,
        };
        struct drm_connector **connector_list;
        int num_connectors, ret;
        bool visible;

        ret = drm_plane_helper_check_update(plane, crtc, fb,
                                            &src, &dest,
                                            DRM_MODE_ROTATE_0,
                                            DRM_PLANE_HELPER_NO_SCALING,
                                            DRM_PLANE_HELPER_NO_SCALING,
                                            false, false, &visible);
        if (ret)
                return ret;

        if (!visible)
                /*
                 * Primary plane isn't visible.  Note that unless a driver
                 * provides their own disable function, this will just
                 * wind up returning -EINVAL to userspace.
                 */
                return plane->funcs->disable_plane(plane, ctx);

        /* Find current connectors for CRTC */
        num_connectors = get_connectors_for_crtc(crtc, NULL, 0);
        BUG_ON(num_connectors == 0);
        connector_list = kcalloc(num_connectors, sizeof(*connector_list),
                                 GFP_KERNEL);
        if (!connector_list)
                return -ENOMEM;
        get_connectors_for_crtc(crtc, connector_list, num_connectors);

        set.connectors = connector_list;
        set.num_connectors = num_connectors;

        /*
         * We call set_config() directly here rather than using
         * drm_mode_set_config_internal.  We're reprogramming the same
         * connectors that were already in use, so we shouldn't need the extra
         * cross-CRTC fb refcounting to accomodate stealing connectors.
         * drm_mode_setplane() already handles the basic refcounting for the
         * framebuffers involved in this operation.
         */
        ret = crtc->funcs->set_config(&set, ctx);

        kfree(connector_list);
        return ret;
}

static int drm_primary_helper_disable(struct drm_plane *plane,
                                      struct drm_modeset_acquire_ctx *ctx)
{
        return -EINVAL;
}

/**
 * drm_primary_helper_destroy() - Helper for primary plane destruction
 * @plane: plane to destroy
 *
 * Provides a default plane destroy handler for primary planes.  This handler
 * is called during CRTC destruction.  We disable the primary plane, remove
 * it from the DRM plane list, and deallocate the plane structure.
 */
void drm_primary_helper_destroy(struct drm_plane *plane)
{
        drm_plane_cleanup(plane);
        kfree(plane);
}
EXPORT_SYMBOL(drm_primary_helper_destroy);

const struct drm_plane_funcs drm_primary_helper_funcs = {
        .update_plane = drm_primary_helper_update,
        .disable_plane = drm_primary_helper_disable,
        .destroy = drm_primary_helper_destroy,
};
EXPORT_SYMBOL(drm_primary_helper_funcs);