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#include <drm/drm_gem.h>
 28
 29#include "drm_crtc_internal.h"
 30
 31/**
 32 * DOC: overview
 33 *
 34 * The KMS API doesn't standardize backing storage object creation and leaves it
 35 * to driver-specific ioctls. Furthermore actually creating a buffer object even
 36 * for GEM-based drivers is done through a driver-specific ioctl - GEM only has
 37 * a common userspace interface for sharing and destroying objects. While not an
 38 * issue for full-fledged graphics stacks that include device-specific userspace
 39 * components (in libdrm for instance), this limit makes DRM-based early boot
 40 * graphics unnecessarily complex.
 41 *
 42 * Dumb objects partly alleviate the problem by providing a standard API to
 43 * create dumb buffers suitable for scanout, which can then be used to create
 44 * KMS frame buffers.
 45 *
 46 * To support dumb objects drivers must implement the &drm_driver.dumb_create
 47 * operation. &drm_driver.dumb_destroy defaults to drm_gem_dumb_destroy() if
 48 * not set and &drm_driver.dumb_map_offset defaults to
 49 * drm_gem_dumb_map_offset(). See the callbacks for further details.
 50 *
 51 * Note that dumb objects may not be used for gpu acceleration, as has been
 52 * attempted on some ARM embedded platforms. Such drivers really must have
 53 * a hardware-specific ioctl to allocate suitable buffer objects.
 54 */
 55
 56int drm_mode_create_dumb_ioctl(struct drm_device *dev,
 57			       void *data, struct drm_file *file_priv)
 58{
 59	struct drm_mode_create_dumb *args = data;
 60	u32 cpp, stride, size;
 61
 62	if (!dev->driver->dumb_create)
 63		return -ENOSYS;
 64	if (!args->width || !args->height || !args->bpp)
 65		return -EINVAL;
 66
 67	/* overflow checks for 32bit size calculations */
 68	if (args->bpp > U32_MAX - 8)
 69		return -EINVAL;
 70	cpp = DIV_ROUND_UP(args->bpp, 8);
 71	if (cpp > U32_MAX / args->width)
 72		return -EINVAL;
 73	stride = cpp * args->width;
 74	if (args->height > U32_MAX / stride)
 75		return -EINVAL;
 76
 77	/* test for wrap-around */
 78	size = args->height * stride;
 79	if (PAGE_ALIGN(size) == 0)
 80		return -EINVAL;
 81
 82	/*
 83	 * handle, pitch and size are output parameters. Zero them out to
 84	 * prevent drivers from accidentally using uninitialized data. Since
 85	 * not all existing userspace is clearing these fields properly we
 86	 * cannot reject IOCTL with garbage in them.
 87	 */
 88	args->handle = 0;
 89	args->pitch = 0;
 90	args->size = 0;
 91
 92	return dev->driver->dumb_create(file_priv, dev, args);
 93}
 94
 95/**
 96 * drm_mode_mmap_dumb_ioctl - create an mmap offset for a dumb backing storage buffer
 97 * @dev: DRM device
 98 * @data: ioctl data
 99 * @file_priv: DRM file info
100 *
101 * Allocate an offset in the drm device node's address space to be able to
102 * memory map a dumb buffer.
103 *
104 * Called by the user via ioctl.
105 *
106 * Returns:
107 * Zero on success, negative errno on failure.
108 */
109int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
110			     void *data, struct drm_file *file_priv)
111{
112	struct drm_mode_map_dumb *args = data;
113
114	if (!dev->driver->dumb_create)
115		return -ENOSYS;
116
117	if (dev->driver->dumb_map_offset)
118		return dev->driver->dumb_map_offset(file_priv, dev,
119						    args->handle,
120						    &args->offset);
121	else
122		return drm_gem_dumb_map_offset(file_priv, dev, args->handle,
123					       &args->offset);
124}
125
126int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
127				void *data, struct drm_file *file_priv)
128{
129	struct drm_mode_destroy_dumb *args = data;
130
131	if (!dev->driver->dumb_create)
132		return -ENOSYS;
133
134	if (dev->driver->dumb_destroy)
135		return dev->driver->dumb_destroy(file_priv, dev, args->handle);
136	else
137		return drm_gem_dumb_destroy(file_priv, dev, args->handle);
138}
139