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