drm_dumb_buffers.c

  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, args->bpp);
140	if (fourcc != DRM_FORMAT_INVALID) {
141		const struct drm_format_info *info = drm_format_info(fourcc);
142
143		if (!info)
144			return -EINVAL;
145		pitch = drm_format_info_min_pitch(info, 0, 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_priv, dev, args->handle,
256					       &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(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, args->handle, file_priv);
300}