1 /* $NetBSD: drm_dumb_buffers.c,v 1.2 2021/12/18 23:44:57 riastradh Exp $ */
2
3 /*
4 * Copyright (c) 2006-2008 Intel Corporation
5 * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
6 * Copyright (c) 2008 Red Hat Inc.
7 * Copyright (c) 2016 Intel Corporation
8 *
9 * Permission to use, copy, modify, distribute, and sell this software and its
10 * documentation for any purpose is hereby granted without fee, provided that
11 * the above copyright notice appear in all copies and that both that copyright
12 * notice and this permission notice appear in supporting documentation, and
13 * that the name of the copyright holders not be used in advertising or
14 * publicity pertaining to distribution of the software without specific,
15 * written prior permission. The copyright holders make no representations
16 * about the suitability of this software for any purpose. It is provided "as
17 * is" without express or implied warranty.
18 *
19 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
20 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
21 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
22 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
23 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
24 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
25 * OF THIS SOFTWARE.
26 */
27
28 #include <sys/cdefs.h>
29 __KERNEL_RCSID(0, "$NetBSD: drm_dumb_buffers.c,v 1.2 2021/12/18 23:44:57 riastradh Exp $");
30
31 #include <drm/drm_device.h>
32 #include <drm/drm_drv.h>
33 #include <drm/drm_gem.h>
34 #include <drm/drm_mode.h>
35
36 #include "drm_crtc_internal.h"
37
38 /**
39 * DOC: overview
40 *
41 * The KMS API doesn't standardize backing storage object creation and leaves it
42 * to driver-specific ioctls. Furthermore actually creating a buffer object even
43 * for GEM-based drivers is done through a driver-specific ioctl - GEM only has
44 * a common userspace interface for sharing and destroying objects. While not an
45 * issue for full-fledged graphics stacks that include device-specific userspace
46 * components (in libdrm for instance), this limit makes DRM-based early boot
47 * graphics unnecessarily complex.
48 *
49 * Dumb objects partly alleviate the problem by providing a standard API to
50 * create dumb buffers suitable for scanout, which can then be used to create
51 * KMS frame buffers.
52 *
53 * To support dumb objects drivers must implement the &drm_driver.dumb_create
54 * operation. &drm_driver.dumb_destroy defaults to drm_gem_dumb_destroy() if
55 * not set and &drm_driver.dumb_map_offset defaults to
56 * drm_gem_dumb_map_offset(). See the callbacks for further details.
57 *
58 * Note that dumb objects may not be used for gpu acceleration, as has been
59 * attempted on some ARM embedded platforms. Such drivers really must have
60 * a hardware-specific ioctl to allocate suitable buffer objects.
61 */
62
drm_mode_create_dumb(struct drm_device * dev,struct drm_mode_create_dumb * args,struct drm_file * file_priv)63 int drm_mode_create_dumb(struct drm_device *dev,
64 struct drm_mode_create_dumb *args,
65 struct drm_file *file_priv)
66 {
67 u32 cpp, stride, size;
68
69 if (!dev->driver->dumb_create)
70 return -ENOSYS;
71 if (!args->width || !args->height || !args->bpp)
72 return -EINVAL;
73
74 /* overflow checks for 32bit size calculations */
75 if (args->bpp > U32_MAX - 8)
76 return -EINVAL;
77 cpp = DIV_ROUND_UP(args->bpp, 8);
78 if (cpp > U32_MAX / args->width)
79 return -EINVAL;
80 stride = cpp * args->width;
81 if (args->height > U32_MAX / stride)
82 return -EINVAL;
83
84 /* test for wrap-around */
85 size = args->height * stride;
86 if (PAGE_ALIGN(size) == 0)
87 return -EINVAL;
88
89 /*
90 * handle, pitch and size are output parameters. Zero them out to
91 * prevent drivers from accidentally using uninitialized data. Since
92 * not all existing userspace is clearing these fields properly we
93 * cannot reject IOCTL with garbage in them.
94 */
95 args->handle = 0;
96 args->pitch = 0;
97 args->size = 0;
98
99 return dev->driver->dumb_create(file_priv, dev, args);
100 }
101
drm_mode_create_dumb_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)102 int drm_mode_create_dumb_ioctl(struct drm_device *dev,
103 void *data, struct drm_file *file_priv)
104 {
105 return drm_mode_create_dumb(dev, data, file_priv);
106 }
107
108 /**
109 * drm_mode_mmap_dumb_ioctl - create an mmap offset for a dumb backing storage buffer
110 * @dev: DRM device
111 * @data: ioctl data
112 * @file_priv: DRM file info
113 *
114 * Allocate an offset in the drm device node's address space to be able to
115 * memory map a dumb buffer.
116 *
117 * Called by the user via ioctl.
118 *
119 * Returns:
120 * Zero on success, negative errno on failure.
121 */
drm_mode_mmap_dumb_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)122 int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
123 void *data, struct drm_file *file_priv)
124 {
125 struct drm_mode_map_dumb *args = data;
126
127 if (!dev->driver->dumb_create)
128 return -ENOSYS;
129
130 if (dev->driver->dumb_map_offset)
131 return dev->driver->dumb_map_offset(file_priv, dev,
132 args->handle,
133 &args->offset);
134 else
135 return drm_gem_dumb_map_offset(file_priv, dev, args->handle,
136 &args->offset);
137 }
138
drm_mode_destroy_dumb(struct drm_device * dev,u32 handle,struct drm_file * file_priv)139 int drm_mode_destroy_dumb(struct drm_device *dev, u32 handle,
140 struct drm_file *file_priv)
141 {
142 if (!dev->driver->dumb_create)
143 return -ENOSYS;
144
145 if (dev->driver->dumb_destroy)
146 return dev->driver->dumb_destroy(file_priv, dev, handle);
147 else
148 return drm_gem_dumb_destroy(file_priv, dev, handle);
149 }
150
drm_mode_destroy_dumb_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)151 int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
152 void *data, struct drm_file *file_priv)
153 {
154 struct drm_mode_destroy_dumb *args = data;
155
156 return drm_mode_destroy_dumb(dev, args->handle, file_priv);
157 }
158