drivers/gpu/drm/xen/xen_drm_front_cfg.c

   1 // SPDX-License-Identifier: GPL-2.0 OR MIT
   2
   3 /*
   4  *  Xen para-virtual DRM device
   5  *
   6  * Copyright (C) 2016-2018 EPAM Systems Inc.
   7  *
   8  * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
   9  */
  10
  11 #include <linux/device.h>
  12
  13 #include <drm/drm_print.h>
  14
  15 #include <xen/interface/io/displif.h>
  16 #include <xen/xenbus.h>
  17
  18 #include "xen_drm_front.h"
  19 #include "xen_drm_front_cfg.h"
  20
  21 static int cfg_connector(struct xen_drm_front_info *front_info,
  22                          struct xen_drm_front_cfg_connector *connector,
  23                          const char *path, int index)
  24 {
  25         char *connector_path;
  26
  27         connector_path = devm_kasprintf(&front_info->xb_dev->dev,
  28                                         GFP_KERNEL, "%s/%d", path, index);
  29         if (!connector_path)
  30                 return -ENOMEM;
  31
  32         if (xenbus_scanf(XBT_NIL, connector_path, XENDISPL_FIELD_RESOLUTION,
  33                          "%d" XENDISPL_RESOLUTION_SEPARATOR "%d",
  34                          &connector->width, &connector->height) < 0) {
  35                 /* either no entry configured or wrong resolution set */
  36                 connector->width = 0;
  37                 connector->height = 0;
  38                 return -EINVAL;
  39         }
  40
  41         connector->xenstore_path = connector_path;
  42
  43         DRM_INFO("Connector %s: resolution %dx%d\n",
  44                  connector_path, connector->width, connector->height);
  45         return 0;
  46 }
  47
  48 int xen_drm_front_cfg_card(struct xen_drm_front_info *front_info,
  49                            struct xen_drm_front_cfg *cfg)
  50 {
  51         struct xenbus_device *xb_dev = front_info->xb_dev;
  52         int ret, i;
  53
  54         if (xenbus_read_unsigned(front_info->xb_dev->nodename,
  55                                  XENDISPL_FIELD_BE_ALLOC, 0)) {
  56                 DRM_INFO("Backend can provide display buffers\n");
  57                 cfg->be_alloc = true;
  58         }
  59
  60         cfg->num_connectors = 0;
  61         for (i = 0; i < ARRAY_SIZE(cfg->connectors); i++) {
  62                 ret = cfg_connector(front_info, &cfg->connectors[i],
  63                                     xb_dev->nodename, i);
  64                 if (ret < 0)
  65                         break;
  66                 cfg->num_connectors++;
  67         }
  68
  69         if (!cfg->num_connectors) {
  70                 DRM_ERROR("No connector(s) configured at %s\n",
  71                           xb_dev->nodename);
  72                 return -ENODEV;
  73         }
  74
  75         return 0;
  76 }
  77