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 #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         return drm_gem_handle_delete(file_priv, handle);
 143 }
 144
 145 int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
 146                                 void *data, struct drm_file *file_priv)
 147 {
 148         struct drm_mode_destroy_dumb *args = data;
 149
 150         return drm_mode_destroy_dumb(dev, args->handle, file_priv);
 151 }