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 
cfg_connector(struct xen_drm_front_info * front_info,struct xen_drm_front_cfg_connector * connector,const char * path,int index)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 
xen_drm_front_cfg_card(struct xen_drm_front_info * front_info,struct xen_drm_front_cfg * cfg)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 
78