drm: document drm_auth.c

Also extract drm_auth.h for nicer grouping.

v2: Nuke the other comments since they don't really explain a lot, and
within the drm core we generally only document functions exported to
drivers: The main audience for these docs are driver writers.

v3: Limit the exposure of drm_master internals by only including
drm_auth.h where it is neede (Chris).

v4: Spelling polish (Emil).

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
diff --git a/include/drm/drm_auth.h b/include/drm/drm_auth.h
new file mode 100644
index 0000000..610223b
--- /dev/null
+++ b/include/drm/drm_auth.h
@@ -0,0 +1,59 @@
+/*
+ * Internal Header for the Direct Rendering Manager
+ *
+ * Copyright 2016 Intel Corporation
+ *
+ * Author: Daniel Vetter <daniel.vetter@ffwll.ch>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef _DRM_AUTH_H_
+#define _DRM_AUTH_H_
+
+/**
+ * struct drm_master - drm master structure
+ *
+ * @refcount: Refcount for this master object.
+ * @dev: Link back to the DRM device
+ * @unique: Unique identifier: e.g. busid. Protected by drm_global_mutex.
+ * @unique_len: Length of unique field. Protected by drm_global_mutex.
+ * @magic_map: Map of used authentication tokens. Protected by struct_mutex.
+ * @lock: DRI lock information.
+ * @driver_priv: Pointer to driver-private information.
+ *
+ * Note that master structures are only relevant for the legacy/primary device
+ * nodes, hence there can only be one per device, not one per drm_minor.
+ */
+struct drm_master {
+	struct kref refcount;
+	struct drm_device *dev;
+	char *unique;
+	int unique_len;
+	struct idr magic_map;
+	struct drm_lock_data lock;
+	void *driver_priv;
+};
+
+struct drm_master *drm_master_get(struct drm_master *master);
+void drm_master_put(struct drm_master **master);
+bool drm_is_current_master(struct drm_file *fpriv);
+
+#endif