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
21static 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(dev: &front_info->xb_dev->dev,
28 GFP_KERNEL, fmt: "%s/%d", path, index);
29 if (!connector_path)
30 return -ENOMEM;
31
32 if (xenbus_scanf(XBT_NIL, dir: connector_path, XENDISPL_FIELD_RESOLUTION,
33 fmt: "%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
48int 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(dir: front_info->xb_dev->nodename,
55 XENDISPL_FIELD_BE_ALLOC, default_val: 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, connector: &cfg->connectors[i],
63 path: xb_dev->nodename, index: 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
78

source code of linux/drivers/gpu/drm/xen/xen_drm_front_cfg.c