1/*
  2 * Copyright (c) 2006-2008 Intel Corporation
  3 * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
  4 * Copyright (c) 2008 Red Hat Inc.
  5 * Copyright (c) 2016 Intel Corporation
  6 *
  7 * Permission to use, copy, modify, distribute, and sell this software and its
  8 * documentation for any purpose is hereby granted without fee, provided that
  9 * the above copyright notice appear in all copies and that both that copyright
 10 * notice and this permission notice appear in supporting documentation, and
 11 * that the name of the copyright holders not be used in advertising or
 12 * publicity pertaining to distribution of the software without specific,
 13 * written prior permission.  The copyright holders make no representations
 14 * about the suitability of this software for any purpose.  It is provided "as
 15 * is" without express or implied warranty.
 16 *
 17 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 18 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 19 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 20 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 21 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 22 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 23 * OF THIS SOFTWARE.
 24 */
 25
 26#include <drm/drmP.h>
 27
 28#include "drm_crtc_internal.h"
 29
 30/**
 31 * DOC: overview
 32 *
 33 * The KMS API doesn't standardize backing storage object creation and leaves it
 34 * to driver-specific ioctls. Furthermore actually creating a buffer object even
 35 * for GEM-based drivers is done through a driver-specific ioctl - GEM only has
 36 * a common userspace interface for sharing and destroying objects. While not an
 37 * issue for full-fledged graphics stacks that include device-specific userspace
 38 * components (in libdrm for instance), this limit makes DRM-based early boot
 39 * graphics unnecessarily complex.
 40 *
 41 * Dumb objects partly alleviate the problem by providing a standard API to
 42 * create dumb buffers suitable for scanout, which can then be used to create
 43 * KMS frame buffers.
 44 *
 45 * To support dumb objects drivers must implement the dumb_create,
 46 * dumb_destroy and dumb_map_offset operations from struct &drm_driver. See
 47 * there for further details.
 48 *
 49 * Note that dumb objects may not be used for gpu acceleration, as has been
 50 * attempted on some ARM embedded platforms. Such drivers really must have
 51 * a hardware-specific ioctl to allocate suitable buffer objects.
 52 */
 53
 54int drm_mode_create_dumb_ioctl(struct drm_device *dev,
 55			       void *data, struct drm_file *file_priv)
 56{
 57	struct drm_mode_create_dumb *args = data;
 58	u32 cpp, stride, size;
 59
 60	if (!dev->driver->dumb_create)
 61		return -ENOSYS;
 62	if (!args->width || !args->height || !args->bpp)
 63		return -EINVAL;
 64
 65	/* overflow checks for 32bit size calculations */
 66	/* NOTE: DIV_ROUND_UP() can overflow */
 67	cpp = DIV_ROUND_UP(args->bpp, 8);
 68	if (!cpp || cpp > 0xffffffffU / args->width)
 69		return -EINVAL;
 70	stride = cpp * args->width;
 71	if (args->height > 0xffffffffU / stride)
 72		return -EINVAL;
 73
 74	/* test for wrap-around */
 75	size = args->height * stride;
 76	if (PAGE_ALIGN(size) == 0)
 77		return -EINVAL;
 78
 79	/*
 80	 * handle, pitch and size are output parameters. Zero them out to
 81	 * prevent drivers from accidentally using uninitialized data. Since
 82	 * not all existing userspace is clearing these fields properly we
 83	 * cannot reject IOCTL with garbage in them.
 84	 */
 85	args->handle = 0;
 86	args->pitch = 0;
 87	args->size = 0;
 88
 89	return dev->driver->dumb_create(file_priv, dev, args);
 90}
 91
 92/**
 93 * drm_mode_mmap_dumb_ioctl - create an mmap offset for a dumb backing storage buffer
 94 * @dev: DRM device
 95 * @data: ioctl data
 96 * @file_priv: DRM file info
 97 *
 98 * Allocate an offset in the drm device node's address space to be able to
 99 * memory map a dumb buffer.
100 *
101 * Called by the user via ioctl.
102 *
103 * Returns:
104 * Zero on success, negative errno on failure.
105 */
106int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
107			     void *data, struct drm_file *file_priv)
108{
109	struct drm_mode_map_dumb *args = data;
110
111	/* call driver ioctl to get mmap offset */
112	if (!dev->driver->dumb_map_offset)
113		return -ENOSYS;
114
115	return dev->driver->dumb_map_offset(file_priv, dev, args->handle, &args->offset);
116}
117
118int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
119				void *data, struct drm_file *file_priv)
120{
121	struct drm_mode_destroy_dumb *args = data;
122
123	if (!dev->driver->dumb_destroy)
124		return -ENOSYS;
125
126	return dev->driver->dumb_destroy(file_priv, dev, args->handle);
127}
128