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      1 /*	$NetBSD: xen_drm_front_cfg.c,v 1.2 2021/12/18 23:45:45 riastradh Exp $	*/
      2 
      3 // SPDX-License-Identifier: GPL-2.0 OR MIT
      4 
      5 /*
      6  *  Xen para-virtual DRM device
      7  *
      8  * Copyright (C) 2016-2018 EPAM Systems Inc.
      9  *
     10  * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko (at) epam.com>
     11  */
     12 
     13 #include <sys/cdefs.h>
     14 __KERNEL_RCSID(0, "$NetBSD: xen_drm_front_cfg.c,v 1.2 2021/12/18 23:45:45 riastradh Exp $");
     15 
     16 #include <linux/device.h>
     17 
     18 #include <drm/drm_print.h>
     19 
     20 #include <xen/interface/io/displif.h>
     21 #include <xen/xenbus.h>
     22 
     23 #include "xen_drm_front.h"
     24 #include "xen_drm_front_cfg.h"
     25 
     26 static int cfg_connector(struct xen_drm_front_info *front_info,
     27 			 struct xen_drm_front_cfg_connector *connector,
     28 			 const char *path, int index)
     29 {
     30 	char *connector_path;
     31 
     32 	connector_path = devm_kasprintf(&front_info->xb_dev->dev,
     33 					GFP_KERNEL, "%s/%d", path, index);
     34 	if (!connector_path)
     35 		return -ENOMEM;
     36 
     37 	if (xenbus_scanf(XBT_NIL, connector_path, XENDISPL_FIELD_RESOLUTION,
     38 			 "%d" XENDISPL_RESOLUTION_SEPARATOR "%d",
     39 			 &connector->width, &connector->height) < 0) {
     40 		/* either no entry configured or wrong resolution set */
     41 		connector->width = 0;
     42 		connector->height = 0;
     43 		return -EINVAL;
     44 	}
     45 
     46 	connector->xenstore_path = connector_path;
     47 
     48 	DRM_INFO("Connector %s: resolution %dx%d\n",
     49 		 connector_path, connector->width, connector->height);
     50 	return 0;
     51 }
     52 
     53 int xen_drm_front_cfg_card(struct xen_drm_front_info *front_info,
     54 			   struct xen_drm_front_cfg *cfg)
     55 {
     56 	struct xenbus_device *xb_dev = front_info->xb_dev;
     57 	int ret, i;
     58 
     59 	if (xenbus_read_unsigned(front_info->xb_dev->nodename,
     60 				 XENDISPL_FIELD_BE_ALLOC, 0)) {
     61 		DRM_INFO("Backend can provide display buffers\n");
     62 		cfg->be_alloc = true;
     63 	}
     64 
     65 	cfg->num_connectors = 0;
     66 	for (i = 0; i < ARRAY_SIZE(cfg->connectors); i++) {
     67 		ret = cfg_connector(front_info, &cfg->connectors[i],
     68 				    xb_dev->nodename, i);
     69 		if (ret < 0)
     70 			break;
     71 		cfg->num_connectors++;
     72 	}
     73 
     74 	if (!cfg->num_connectors) {
     75 		DRM_ERROR("No connector(s) configured at %s\n",
     76 			  xb_dev->nodename);
     77 		return -ENODEV;
     78 	}
     79 
     80 	return 0;
     81 }
     82 
     83