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/drmP.h>
  27 #include <drm/drm_gem.h>
  28
  29 #include "drm_crtc_internal.h"
  30
  31 /**
  32  * DOC: overview
  33  *
  34  * The KMS API doesn't standardize backing storage object creation and leaves it
  35  * to driver-specific ioctls. Furthermore actually creating a buffer object even
  36  * for GEM-based drivers is done through a driver-specific ioctl - GEM only has
  37  * a common userspace interface for sharing and destroying objects. While not an
  38  * issue for full-fledged graphics stacks that include device-specific userspace
  39  * components (in libdrm for instance), this limit makes DRM-based early boot
  40  * graphics unnecessarily complex.
  41  *
  42  * Dumb objects partly alleviate the problem by providing a standard API to
  43  * create dumb buffers suitable for scanout, which can then be used to create
  44  * KMS frame buffers.
  45  *
  46  * To support dumb objects drivers must implement the &drm_driver.dumb_create
  47  * operation. &drm_driver.dumb_destroy defaults to drm_gem_dumb_destroy() if
  48  * not set and &drm_driver.dumb_map_offset defaults to
  49  * drm_gem_dumb_map_offset(). See the callbacks for further details.
  50  *
  51  * Note that dumb objects may not be used for gpu acceleration, as has been
  52  * attempted on some ARM embedded platforms. Such drivers really must have
  53  * a hardware-specific ioctl to allocate suitable buffer objects.
  54  */
  55
  56 int drm_mode_create_dumb_ioctl(struct drm_device *dev,
  57                                void *data, struct drm_file *file_priv)
  58 {
  59         struct drm_mode_create_dumb *args = data;
  60         u32 cpp, stride, size;
  61
  62         if (!dev->driver->dumb_create)
  63                 return -ENOSYS;
  64         if (!args->width || !args->height || !args->bpp)
  65                 return -EINVAL;
  66
  67         /* overflow checks for 32bit size calculations */
  68         /* NOTE: DIV_ROUND_UP() can overflow */
  69         cpp = DIV_ROUND_UP(args->bpp, 8);
  70         if (!cpp || cpp > 0xffffffffU / args->width)
  71                 return -EINVAL;
  72         stride = cpp * args->width;
  73         if (args->height > 0xffffffffU / stride)
  74                 return -EINVAL;
  75
  76         /* test for wrap-around */
  77         size = args->height * stride;
  78         if (PAGE_ALIGN(size) == 0)
  79                 return -EINVAL;
  80
  81         /*
  82          * handle, pitch and size are output parameters. Zero them out to
  83          * prevent drivers from accidentally using uninitialized data. Since
  84          * not all existing userspace is clearing these fields properly we
  85          * cannot reject IOCTL with garbage in them.
  86          */
  87         args->handle = 0;
  88         args->pitch = 0;
  89         args->size = 0;
  90
  91         return dev->driver->dumb_create(file_priv, dev, args);
  92 }
  93
  94 /**
  95  * drm_mode_mmap_dumb_ioctl - create an mmap offset for a dumb backing storage buffer
  96  * @dev: DRM device
  97  * @data: ioctl data
  98  * @file_priv: DRM file info
  99  *
 100  * Allocate an offset in the drm device node's address space to be able to
 101  * memory map a dumb buffer.
 102  *
 103  * Called by the user via ioctl.
 104  *
 105  * Returns:
 106  * Zero on success, negative errno on failure.
 107  */
 108 int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
 109                              void *data, struct drm_file *file_priv)
 110 {
 111         struct drm_mode_map_dumb *args = data;
 112
 113         if (!dev->driver->dumb_create)
 114                 return -ENOSYS;
 115
 116         if (dev->driver->dumb_map_offset)
 117                 return dev->driver->dumb_map_offset(file_priv, dev,
 118                                                     args->handle,
 119                                                     &args->offset);
 120         else
 121                 return drm_gem_dumb_map_offset(file_priv, dev, args->handle,
 122                                                &args->offset);
 123 }
 124
 125 int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
 126                                 void *data, struct drm_file *file_priv)
 127 {
 128         struct drm_mode_destroy_dumb *args = data;
 129
 130         if (!dev->driver->dumb_create)
 131                 return -ENOSYS;
 132
 133         if (dev->driver->dumb_destroy)
 134                 return dev->driver->dumb_destroy(file_priv, dev, args->handle);
 135         else
 136                 return drm_gem_dumb_destroy(file_priv, dev, args->handle);
 137 }
 138