1 files changed, 77 insertions, 0 deletions
diff --git a/drivers/gpu/drm/xen/xen_drm_front_cfg.c b/drivers/gpu/drm/xen/xen_drm_front_cfg.c
new file mode 100644
index 000000000000..5baf2b9de93c
--- /dev/null
+++ b/drivers/gpu/drm/xen/xen_drm_front_cfg.c
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+
+/*
+ *  Xen para-virtual DRM device
+ *
+ * Copyright (C) 2016-2018 EPAM Systems Inc.
+ *
+ * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
+ */
+
+#include <drm/drmP.h>
+
+#include <linux/device.h>
+
+#include <xen/interface/io/displif.h>
+#include <xen/xenbus.h>
+
+#include "xen_drm_front.h"
+#include "xen_drm_front_cfg.h"
+
+static int cfg_connector(struct xen_drm_front_info *front_info,
+			 struct xen_drm_front_cfg_connector *connector,
+			 const char *path, int index)
+{
+	char *connector_path;
+
+	connector_path = devm_kasprintf(&front_info->xb_dev->dev,
+					GFP_KERNEL, "%s/%d", path, index);
+	if (!connector_path)
+		return -ENOMEM;
+
+	if (xenbus_scanf(XBT_NIL, connector_path, XENDISPL_FIELD_RESOLUTION,
+			 "%d" XENDISPL_RESOLUTION_SEPARATOR "%d",
+			 &connector->width, &connector->height) < 0) {
+		/* either no entry configured or wrong resolution set */
+		connector->width = 0;
+		connector->height = 0;
+		return -EINVAL;
+	}
+
+	connector->xenstore_path = connector_path;
+
+	DRM_INFO("Connector %s: resolution %dx%d\n",
+		 connector_path, connector->width, connector->height);
+	return 0;
+}
+
+int xen_drm_front_cfg_card(struct xen_drm_front_info *front_info,
+			   struct xen_drm_front_cfg *cfg)
+{
+	struct xenbus_device *xb_dev = front_info->xb_dev;
+	int ret, i;
+
+	if (xenbus_read_unsigned(front_info->xb_dev->nodename,
+				 XENDISPL_FIELD_BE_ALLOC, 0)) {
+		DRM_INFO("Backend can provide display buffers\n");
+		cfg->be_alloc = true;
+	}
+
+	cfg->num_connectors = 0;
+	for (i = 0; i < ARRAY_SIZE(cfg->connectors); i++) {
+		ret = cfg_connector(front_info, &cfg->connectors[i],
+				    xb_dev->nodename, i);
+		if (ret < 0)
+			break;
+		cfg->num_connectors++;
+	}
+
+	if (!cfg->num_connectors) {
+		DRM_ERROR("No connector(s) configured at %s\n",
+			  xb_dev->nodename);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+