linux-imx

/*

 * Created: Fri Jan  8 09:01:26 1999 by faith@valinux.com

 *

 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.

 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.

 * All Rights Reserved.

 *

 * Author Rickard E. (Rik) Faith <faith@valinux.com>

 * Author Gareth Hughes <gareth@valinux.com>

 *

 * 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.

 */

​

#include <drm/drm_ioctl.h>

#include <drm/drmP.h>

#include <drm/drm_auth.h>

#include "drm_legacy.h"

#include "drm_internal.h"

#include "drm_crtc_internal.h"

​

#include <linux/pci.h>

#include <linux/export.h>

#include <linux/nospec.h>

​

/**

 * DOC: getunique and setversion story

 *

 * BEWARE THE DRAGONS! MIND THE TRAPDOORS!

 *

 * In an attempt to warn anyone else who's trying to figure out what's going

 * on here, I'll try to summarize the story. First things first, let's clear up

 * the names, because the kernel internals, libdrm and the ioctls are all named

 * differently:

 *

 *  - GET_UNIQUE ioctl, implemented by drm_getunique is wrapped up in libdrm

 *    through the drmGetBusid function.

 *  - The libdrm drmSetBusid function is backed by the SET_UNIQUE ioctl. All

 *    that code is nerved in the kernel with drm_invalid_op().

 *  - The internal set_busid kernel functions and driver callbacks are

 *    exclusively use by the SET_VERSION ioctl, because only drm 1.0 (which is

 *    nerved) allowed userspace to set the busid through the above ioctl.

 *  - Other ioctls and functions involved are named consistently.

 *

 * For anyone wondering what's the difference between drm 1.1 and 1.4: Correctly

 * handling pci domains in the busid on ppc. Doing this correctly was only

 * implemented in libdrm in 2010, hence can't be nerved yet. No one knows what's