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/drm_device.h>
27 #include <drm/drm_drv.h>
28 #include <drm/drm_gem.h>
29 #include <drm/drm_mode.h>
30 
31 #include "drm_crtc_internal.h"
32 #include "drm_internal.h"
33 
34 /**
35  * DOC: overview
36  *
37  * The KMS API doesn't standardize backing storage object creation and leaves it
38  * to driver-specific ioctls. Furthermore actually creating a buffer object even
39  * for GEM-based drivers is done through a driver-specific ioctl - GEM only has
40  * a common userspace interface for sharing and destroying objects. While not an
41  * issue for full-fledged graphics stacks that include device-specific userspace
42  * components (in libdrm for instance), this limit makes DRM-based early boot
43  * graphics unnecessarily complex.
44  *
45  * Dumb objects partly alleviate the problem by providing a standard API to
46  * create dumb buffers suitable for scanout, which can then be used to create
47  * KMS frame buffers.
48  *
49  * To support dumb objects drivers must implement the &drm_driver.dumb_create
50  * and &drm_driver.dumb_map_offset operations (the latter defaults to
51  * drm_gem_dumb_map_offset() if not set). Drivers that don't use GEM handles
52  * additionally need to implement the &drm_driver.dumb_destroy operation. See
53  * the callbacks for further details.
54  *
55  * Note that dumb objects may not be used for gpu acceleration, as has been
56  * attempted on some ARM embedded platforms. Such drivers really must have
57  * a hardware-specific ioctl to allocate suitable buffer objects.
58  */
59 
60 int drm_mode_create_dumb(struct drm_device *dev,
61 			 struct drm_mode_create_dumb *args,
62 			 struct drm_file *file_priv)
63 {
64 	u32 cpp, stride, size;
65 
66 	if (!dev->driver->dumb_create)
67 		return -ENOSYS;
68 	if (!args->width || !args->height || !args->bpp)
69 		return -EINVAL;
70 
71 	/* overflow checks for 32bit size calculations */
72 	if (args->bpp > U32_MAX - 8)
73 		return -EINVAL;
74 	cpp = DIV_ROUND_UP(args->bpp, 8);
75 	if (cpp > U32_MAX / args->width)
76 		return -EINVAL;
77 	stride = cpp * args->width;
78 	if (args->height > U32_MAX / stride)
79 		return -EINVAL;
80 
81 	/* test for wrap-around */
82 	size = args->height * stride;
83 	if (PAGE_ALIGN(size) == 0)
84 		return -EINVAL;
85 
86 	/*
87 	 * handle, pitch and size are output parameters. Zero them out to
88 	 * prevent drivers from accidentally using uninitialized data. Since
89 	 * not all existing userspace is clearing these fields properly we
90 	 * cannot reject IOCTL with garbage in them.
91 	 */
92 	args->handle = 0;
93 	args->pitch = 0;
94 	args->size = 0;
95 
96 	return dev->driver->dumb_create(file_priv, dev, args);
97 }
98 
99 int drm_mode_create_dumb_ioctl(struct drm_device *dev,
100 			       void *data, struct drm_file *file_priv)
101 {
102 	return drm_mode_create_dumb(dev, data, file_priv);
103 }
104 
105 /**
106  * drm_mode_mmap_dumb_ioctl - create an mmap offset for a dumb backing storage buffer
107  * @dev: DRM device
108  * @data: ioctl data
109  * @file_priv: DRM file info
110  *
111  * Allocate an offset in the drm device node's address space to be able to
112  * memory map a dumb buffer.
113  *
114  * Called by the user via ioctl.
115  *
116  * Returns:
117  * Zero on success, negative errno on failure.
118  */
119 int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
120 			     void *data, struct drm_file *file_priv)
121 {
122 	struct drm_mode_map_dumb *args = data;
123 
124 	if (!dev->driver->dumb_create)
125 		return -ENOSYS;
126 
127 	if (dev->driver->dumb_map_offset)
128 		return dev->driver->dumb_map_offset(file_priv, dev,
129 						    args->handle,
130 						    &args->offset);
131 	else
132 		return drm_gem_dumb_map_offset(file_priv, dev, args->handle,
133 					       &args->offset);
134 }
135 
136 int drm_mode_destroy_dumb(struct drm_device *dev, u32 handle,
137 			  struct drm_file *file_priv)
138 {
139 	if (!dev->driver->dumb_create)
140 		return -ENOSYS;
141 
142 	if (dev->driver->dumb_destroy)
143 		return dev->driver->dumb_destroy(file_priv, dev, handle);
144 	else
145 		return drm_gem_dumb_destroy(file_priv, dev, handle);
146 }
147 
148 int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
149 				void *data, struct drm_file *file_priv)
150 {
151 	struct drm_mode_destroy_dumb *args = data;
152 
153 	return drm_mode_destroy_dumb(dev, args->handle, file_priv);
154 }
155