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(&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
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(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
78