// 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 <linux/device.h>

#include <drm/drm_print.h>

#include <xen/interface/io/displif.h>
#include <xen/xenbus.h>

#include "xen_drm_front.h"
#include "xen_drm_front_cfg.h"

static int cfg_connector(struct xen_drm_front_info *front_info,
                         struct xen_drm_front_cfg_connector *connector,
                         const char *path, int index)
{
        char *connector_path;

        connector_path = devm_kasprintf(&front_info->xb_dev->dev,
                                        GFP_KERNEL, "%s/%d", path, index);
        if (!connector_path)
                return -ENOMEM;

        if (xenbus_scanf(XBT_NIL, connector_path, XENDISPL_FIELD_RESOLUTION,
                         "%d" XENDISPL_RESOLUTION_SEPARATOR "%d",
                         &connector->width, &connector->height) < 0) {
                /* either no entry configured or wrong resolution set */
                connector->width = 0;
                connector->height = 0;
                return -EINVAL;
        }

        connector->xenstore_path = connector_path;

        DRM_INFO("Connector %s: resolution %dx%d\n",
                 connector_path, connector->width, connector->height);
        return 0;
}

int xen_drm_front_cfg_card(struct xen_drm_front_info *front_info,
                           struct xen_drm_front_cfg *cfg)
{
        struct xenbus_device *xb_dev = front_info->xb_dev;
        int ret, i;

        if (xenbus_read_unsigned(front_info->xb_dev->nodename,
                                 XENDISPL_FIELD_BE_ALLOC, 0)) {
                DRM_INFO("Backend can provide display buffers\n");
                cfg->be_alloc = true;
        }

        cfg->num_connectors = 0;
        for (i = 0; i < ARRAY_SIZE(cfg->connectors); i++) {
                ret = cfg_connector(front_info, &cfg->connectors[i],
                                    xb_dev->nodename, i);
                if (ret < 0)
                        break;
                cfg->num_connectors++;
        }

        if (!cfg->num_connectors) {
                DRM_ERROR("No connector(s) configured at %s\n",
                          xb_dev->nodename);
                return -ENODEV;
        }

        return 0;
}