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_dumb_buffers.h>
29#include <drm/drm_fourcc.h>
30#include <drm/drm_gem.h>
31#include <drm/drm_mode.h>
32#include <drm/drm_print.h>
33
34#include "drm_crtc_internal.h"
35#include "drm_internal.h"
36
37/**
38 * DOC: overview
39 *
40 * The KMS API doesn't standardize backing storage object creation and leaves it
41 * to driver-specific ioctls. Furthermore actually creating a buffer object even
42 * for GEM-based drivers is done through a driver-specific ioctl - GEM only has
43 * a common userspace interface for sharing and destroying objects. While not an
44 * issue for full-fledged graphics stacks that include device-specific userspace
45 * components (in libdrm for instance), this limit makes DRM-based early boot
46 * graphics unnecessarily complex.
47 *
48 * Dumb objects partly alleviate the problem by providing a standard API to
49 * create dumb buffers suitable for scanout, which can then be used to create
50 * KMS frame buffers.
51 *
52 * To support dumb objects drivers must implement the &drm_driver.dumb_create
53 * and &drm_driver.dumb_map_offset operations (the latter defaults to
54 * drm_gem_dumb_map_offset() if not set). Drivers that don't use GEM handles
55 * additionally need to implement the &drm_driver.dumb_destroy operation. See
56 * 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
63static int drm_mode_align_dumb(struct drm_mode_create_dumb *args,
64 unsigned long hw_pitch_align,
65 unsigned long hw_size_align)
66{
67 u32 pitch = args->pitch;
68 u32 size;
69
70 if (!pitch)
71 return -EINVAL;
72
73 if (hw_pitch_align)
74 pitch = roundup(pitch, hw_pitch_align);
75
76 if (!hw_size_align)
77 hw_size_align = PAGE_SIZE;
78 else if (!IS_ALIGNED(hw_size_align, PAGE_SIZE))
79 return -EINVAL; /* TODO: handle this if necessary */
80
81 if (check_mul_overflow(args->height, pitch, &size))
82 return -EINVAL;
83 size = ALIGN(size, hw_size_align);
84 if (!size)
85 return -EINVAL;
86
87 args->pitch = pitch;
88 args->size = size;
89
90 return 0;
91}
92
93/**
94 * drm_mode_size_dumb - Calculates the scanline and buffer sizes for dumb buffers
95 * @dev: DRM device
96 * @args: Parameters for the dumb buffer
97 * @hw_pitch_align: Hardware scanline alignment in bytes
98 * @hw_size_align: Hardware buffer-size alignment in bytes
99 *
100 * The helper drm_mode_size_dumb() calculates the size of the buffer
101 * allocation and the scanline size for a dumb buffer. Callers have to
102 * set the buffers width, height and color mode in the argument @arg.
103 * The helper validates the correctness of the input and tests for
104 * possible overflows. If successful, it returns the dumb buffer's
105 * required scanline pitch and size in &args.
106 *
107 * The parameter @hw_pitch_align allows the driver to specifies an
108 * alignment for the scanline pitch, if the hardware requires any. The
109 * calculated pitch will be a multiple of the alignment. The parameter
110 * @hw_size_align allows to specify an alignment for buffer sizes. The
111 * provided alignment should represent requirements of the graphics
112 * hardware. drm_mode_size_dumb() handles GEM-related constraints
113 * automatically across all drivers and hardware. For example, the
114 * returned buffer size is always a multiple of PAGE_SIZE, which is
115 * required by mmap().
116 *
117 * Returns:
118 * Zero on success, or a negative error code otherwise.
119 */
120int drm_mode_size_dumb(struct drm_device *dev,
121 struct drm_mode_create_dumb *args,
122 unsigned long hw_pitch_align,
123 unsigned long hw_size_align)
124{
125 u64 pitch = 0;
126 u32 fourcc;
127
128 /*
129 * The scanline pitch depends on the buffer width and the color
130 * format. The latter is specified as a color-mode constant for
131 * which we first have to find the corresponding color format.
132 *
133 * Different color formats can have the same color-mode constant.
134 * For example XRGB8888 and BGRX8888 both have a color mode of 32.
135 * It is possible to use different formats for dumb-buffer allocation
136 * and rendering as long as all involved formats share the same
137 * color-mode constant.
138 */
139 fourcc = drm_driver_color_mode_format(dev, color_mode: args->bpp);
140 if (fourcc != DRM_FORMAT_INVALID) {
141 const struct drm_format_info *info = drm_format_info(format: fourcc);
142
143 if (!info)
144 return -EINVAL;
145 pitch = drm_format_info_min_pitch(info, plane: 0, buffer_width: args->width);
146 } else if (args->bpp) {
147 /*
148 * Some userspace throws in arbitrary values for bpp and
149 * relies on the kernel to figure it out. In this case we
150 * fall back to the old method of using bpp directly. The
151 * over-commitment of memory from the rounding is acceptable
152 * for compatibility with legacy userspace. We have a number
153 * of deprecated legacy values that are explicitly supported.
154 */
155 switch (args->bpp) {
156 default:
157 drm_warn_once(dev,
158 "Unknown color mode %u; guessing buffer size.\n",
159 args->bpp);
160 fallthrough;
161 /*
162 * These constants represent various YUV formats supported by
163 * drm_gem_afbc_get_bpp().
164 */
165 case 12: // DRM_FORMAT_YUV420_8BIT
166 case 15: // DRM_FORMAT_YUV420_10BIT
167 case 30: // DRM_FORMAT_VUY101010
168 fallthrough;
169 /*
170 * Used by Mesa and Gstreamer to allocate NV formats and others
171 * as RGB buffers. Technically, XRGB16161616F formats are RGB,
172 * but the dumb buffers are not supposed to be used for anything
173 * beyond 32 bits per pixels.
174 */
175 case 10: // DRM_FORMAT_NV{15,20,30}, DRM_FORMAT_P010
176 case 64: // DRM_FORMAT_{XRGB,XBGR,ARGB,ABGR}16161616F
177 pitch = args->width * DIV_ROUND_UP(args->bpp, SZ_8);
178 break;
179 }
180 }
181
182 if (!pitch || pitch > U32_MAX)
183 return -EINVAL;
184
185 args->pitch = pitch;
186
187 return drm_mode_align_dumb(args, hw_pitch_align, hw_size_align);
188}
189EXPORT_SYMBOL(drm_mode_size_dumb);
190
191int drm_mode_create_dumb(struct drm_device *dev,
192 struct drm_mode_create_dumb *args,
193 struct drm_file *file_priv)
194{
195 u32 cpp, stride, size;
196
197 if (!dev->driver->dumb_create)
198 return -ENOSYS;
199 if (!args->width || !args->height || !args->bpp)
200 return -EINVAL;
201
202 /* overflow checks for 32bit size calculations */
203 if (args->bpp > U32_MAX - 8)
204 return -EINVAL;
205 cpp = DIV_ROUND_UP(args->bpp, 8);
206 if (cpp > U32_MAX / args->width)
207 return -EINVAL;
208 stride = cpp * args->width;
209 if (args->height > U32_MAX / stride)
210 return -EINVAL;
211
212 /* test for wrap-around */
213 size = args->height * stride;
214 if (PAGE_ALIGN(size) == 0)
215 return -EINVAL;
216
217 /*
218 * handle, pitch and size are output parameters. Zero them out to
219 * prevent drivers from accidentally using uninitialized data. Since
220 * not all existing userspace is clearing these fields properly we
221 * cannot reject IOCTL with garbage in them.
222 */
223 args->handle = 0;
224 args->pitch = 0;
225 args->size = 0;
226
227 return dev->driver->dumb_create(file_priv, dev, args);
228}
229
230int drm_mode_create_dumb_ioctl(struct drm_device *dev,
231 void *data, struct drm_file *file_priv)
232{
233 struct drm_mode_create_dumb *args = data;
234 int err;
235
236 err = drm_mode_create_dumb(dev, args, file_priv);
237 if (err) {
238 args->handle = 0;
239 args->pitch = 0;
240 args->size = 0;
241 }
242 return err;
243}
244
245static int drm_mode_mmap_dumb(struct drm_device *dev, struct drm_mode_map_dumb *args,
246 struct drm_file *file_priv)
247{
248 if (!dev->driver->dumb_create)
249 return -ENOSYS;
250
251 if (dev->driver->dumb_map_offset)
252 return dev->driver->dumb_map_offset(file_priv, dev, args->handle,
253 &args->offset);
254 else
255 return drm_gem_dumb_map_offset(file: file_priv, dev, handle: args->handle,
256 offset: &args->offset);
257}
258
259/**
260 * drm_mode_mmap_dumb_ioctl - create an mmap offset for a dumb backing storage buffer
261 * @dev: DRM device
262 * @data: ioctl data
263 * @file_priv: DRM file info
264 *
265 * Allocate an offset in the drm device node's address space to be able to
266 * memory map a dumb buffer.
267 *
268 * Called by the user via ioctl.
269 *
270 * Returns:
271 * Zero on success, negative errno on failure.
272 */
273int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
274 void *data, struct drm_file *file_priv)
275{
276 struct drm_mode_map_dumb *args = data;
277 int err;
278
279 err = drm_mode_mmap_dumb(dev, args, file_priv);
280 if (err)
281 args->offset = 0;
282 return err;
283}
284
285int drm_mode_destroy_dumb(struct drm_device *dev, u32 handle,
286 struct drm_file *file_priv)
287{
288 if (!dev->driver->dumb_create)
289 return -ENOSYS;
290
291 return drm_gem_handle_delete(filp: file_priv, handle);
292}
293
294int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
295 void *data, struct drm_file *file_priv)
296{
297 struct drm_mode_destroy_dumb *args = data;
298
299 return drm_mode_destroy_dumb(dev, handle: args->handle, file_priv);
300}
301

source code of linux/drivers/gpu/drm/drm_dumb_buffers.c