// SPDX-License-Identifier: MIT
/*
 * Copyright © 2023 Intel Corporation
 */

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_atomic_uapi.h>
#include <drm/drm_print.h>

#include "intel_atomic.h"
#include "intel_crtc.h"
#include "intel_display_core.h"
#include "intel_display_types.h"
#include "intel_load_detect.h"

/* VESA 640x480x72Hz mode to set on the pipe */
static const struct drm_display_mode load_detect_mode = {
        DRM_MODE("640x480", DRM_MODE_TYPE_DEFAULT, 31500, 640, 664,
                 704, 832, 0, 480, 489, 491, 520, 0, DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC),
};

static int intel_modeset_disable_planes(struct drm_atomic_state *state,
                                        struct drm_crtc *crtc)
{
        struct drm_plane *plane;
        struct drm_plane_state *plane_state;
        int ret, i;

        ret = drm_atomic_add_affected_planes(state, crtc);
        if (ret)
                return ret;

        for_each_new_plane_in_state(state, plane, plane_state, i) {
                if (plane_state->crtc != crtc)
                        continue;

                ret = drm_atomic_set_crtc_for_plane(plane_state, NULL);
                if (ret)
                        return ret;

                drm_atomic_set_fb_for_plane(plane_state, NULL);
        }

        return 0;
}

struct drm_atomic_state *
intel_load_detect_get_pipe(struct drm_connector *connector,
                           struct drm_modeset_acquire_ctx *ctx)
{
        struct intel_display *display = to_intel_display(connector->dev);
        struct intel_encoder *encoder =
                intel_attached_encoder(to_intel_connector(connector));
        struct intel_crtc *possible_crtc;
        struct intel_crtc *crtc = NULL;
        struct drm_mode_config *config = &display->drm->mode_config;
        struct drm_atomic_state *state = NULL, *restore_state = NULL;
        struct drm_connector_state *connector_state;
        struct intel_crtc_state *crtc_state;
        int ret;

        drm_dbg_kms(display->drm, "[CONNECTOR:%d:%s], [ENCODER:%d:%s]\n",
                    connector->base.id, connector->name,
                    encoder->base.base.id, encoder->base.name);

        drm_WARN_ON(display->drm, !drm_modeset_is_locked(&config->connection_mutex));

        /*
         * Algorithm gets a little messy:
         *
         *   - if the connector already has an assigned crtc, use it (but make
         *     sure it's on first)
         *
         *   - try to find the first unused crtc that can drive this connector,
         *     and use that if we find one
         */

        /* See if we already have a CRTC for this connector */
        if (connector->state->crtc) {
                crtc = to_intel_crtc(connector->state->crtc);

                ret = drm_modeset_lock(&crtc->base.mutex, ctx);
                if (ret)
                        goto fail;

                /* Make sure the crtc and connector are running */
                goto found;
        }

        /* Find an unused one (if possible) */
        for_each_intel_crtc(display->drm, possible_crtc) {
                if (!(encoder->base.possible_crtcs &
                      drm_crtc_mask(&possible_crtc->base)))
                        continue;

                ret = drm_modeset_lock(&possible_crtc->base.mutex, ctx);
                if (ret)
                        goto fail;

                if (possible_crtc->base.state->enable) {
                        drm_modeset_unlock(&possible_crtc->base.mutex);
                        continue;
                }

                crtc = possible_crtc;
                break;
        }

        /*
         * If we didn't find an unused CRTC, don't use any.
         */
        if (!crtc) {
                drm_dbg_kms(display->drm,
                            "no pipe available for load-detect\n");
                ret = -ENODEV;
                goto fail;
        }

found:
        state = drm_atomic_state_alloc(display->drm);
        restore_state = drm_atomic_state_alloc(display->drm);
        if (!state || !restore_state) {
                ret = -ENOMEM;
                goto fail;
        }

        state->acquire_ctx = ctx;
        to_intel_atomic_state(state)->internal = true;

        restore_state->acquire_ctx = ctx;
        to_intel_atomic_state(restore_state)->internal = true;

        connector_state = drm_atomic_get_connector_state(state, connector);
        if (IS_ERR(connector_state)) {
                ret = PTR_ERR(connector_state);
                goto fail;
        }

        ret = drm_atomic_set_crtc_for_connector(connector_state, &crtc->base);
        if (ret)
                goto fail;

        crtc_state = intel_atomic_get_crtc_state(state, crtc);
        if (IS_ERR(crtc_state)) {
                ret = PTR_ERR(crtc_state);
                goto fail;
        }

        crtc_state->uapi.active = true;

        ret = drm_atomic_set_mode_for_crtc(&crtc_state->uapi,
                                           &load_detect_mode);
        if (ret)
                goto fail;

        ret = intel_modeset_disable_planes(state, &crtc->base);
        if (ret)
                goto fail;

        ret = PTR_ERR_OR_ZERO(drm_atomic_get_connector_state(restore_state, connector));
        if (!ret)
                ret = PTR_ERR_OR_ZERO(drm_atomic_get_crtc_state(restore_state, &crtc->base));
        if (!ret)
                ret = drm_atomic_add_affected_planes(restore_state, &crtc->base);
        if (ret) {
                drm_dbg_kms(display->drm,
                            "Failed to create a copy of old state to restore: %i\n",
                            ret);
                goto fail;
        }

        ret = drm_atomic_commit(state);
        if (ret) {
                drm_dbg_kms(display->drm,
                            "failed to set mode on load-detect pipe\n");
                goto fail;
        }

        drm_atomic_state_put(state);

        /* let the connector get through one full cycle before testing */
        intel_crtc_wait_for_next_vblank(crtc);

        return restore_state;

fail:
        if (state) {
                drm_atomic_state_put(state);
                state = NULL;
        }
        if (restore_state) {
                drm_atomic_state_put(restore_state);
                restore_state = NULL;
        }

        if (ret == -EDEADLK)
                return ERR_PTR(ret);

        return NULL;
}

void intel_load_detect_release_pipe(struct drm_connector *connector,
                                    struct drm_atomic_state *state,
                                    struct drm_modeset_acquire_ctx *ctx)
{
        struct intel_display *display = to_intel_display(connector->dev);
        struct intel_encoder *intel_encoder =
                intel_attached_encoder(to_intel_connector(connector));
        struct drm_encoder *encoder = &intel_encoder->base;
        int ret;

        drm_dbg_kms(display->drm, "[CONNECTOR:%d:%s], [ENCODER:%d:%s]\n",
                    connector->base.id, connector->name,
                    encoder->base.id, encoder->name);

        if (IS_ERR_OR_NULL(state))
                return;

        ret = drm_atomic_helper_commit_duplicated_state(state, ctx);
        if (ret)
                drm_dbg_kms(display->drm,
                            "Couldn't release load detect pipe: %i\n", ret);
        drm_atomic_state_put(state);
}