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 &drm_driver.dumb_create,
46  * &drm_driver.dumb_destroy and &drm_driver.dumb_map_offset operations. 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 
54 int 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  */
106 int 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 
118 int 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 
129