backend-drm: Teach drm_property_info_populate() to retrieve range values

Useful for zpos range values.

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Suggested-by: Daniel Stone <daniel.stone@collabora.com>

libweston/backend-drm/drm-internal.h

@@ -144,8 +144,11 @@ struct drm_property_enum_info {
 struct drm_property_info {
 	const char *name; /**< name as string (static, not freed) */
 	uint32_t prop_id; /**< KMS property object ID */
+	uint32_t flags;
 	unsigned int num_enum_values; /**< number of enum values */
 	struct drm_property_enum_info *enum_values; /**< array of enum values */
+	unsigned int num_range_values;
+	uint64_t range_values[2];
 };
 
 /**
@@ -579,6 +582,9 @@ uint64_t
 drm_property_get_value(struct drm_property_info *info,
 		       const drmModeObjectProperties *props,
 		       uint64_t def);
+uint64_t *
+drm_property_get_range_values(struct drm_property_info *info,
+			      const drmModeObjectProperties *props);
 int
 drm_plane_populate_formats(struct drm_plane *plane, const drmModePlane *kplane,
 			   const drmModeObjectProperties *props);

libweston/backend-drm/kms.c

@@ -202,6 +202,42 @@ drm_property_get_value(struct drm_property_info *info,
 	return def;
 }
 
+/**
+ * Get the current range values of a KMS property
+ *
+ * Given a drmModeObjectGetProperties return, as well as the drm_property_info
+ * for the target property, return the current range values of that property,
+ *
+ * If the property is not present, or there's no it is not a prop range then
+ * NULL will be returned.
+ *
+ * @param info Internal structure for property to look up
+ * @param props Raw KMS properties for the target object
+ */
+uint64_t *
+drm_property_get_range_values(struct drm_property_info *info,
+			      const drmModeObjectProperties *props)
+{
+	unsigned int i;
+
+	if (info->prop_id == 0)
+		return NULL;
+
+	for (i = 0; i < props->count_props; i++) {
+
+		if (props->props[i] != info->prop_id)
+			continue;
+
+		if (!(info->flags & DRM_MODE_PROP_RANGE) &&
+		    !(info->flags & DRM_MODE_PROP_SIGNED_RANGE))
+			continue;
+
+		return info->range_values;
+	}
+
+	return NULL;
+}
+
 /**
  * Cache DRM property values
  *
@@ -294,6 +330,15 @@ drm_property_info_populate(struct drm_backend *b,
 		}
 
 		info[j].prop_id = props->props[i];
+		info[j].flags = prop->flags;
+
+		if (prop->flags & DRM_MODE_PROP_RANGE ||
+		    prop->flags & DRM_MODE_PROP_SIGNED_RANGE) {
+			info[j].num_range_values = prop->count_values;
+			for (int i = 0; i < prop->count_values; i++)
+				info[j].range_values[i] = prop->values[i];
+		}
+
 
 		if (info[j].num_enum_values == 0) {
 			drmModeFreeProperty(prop);