LXR linux/drivers/gpu/drm/drm_dumb

   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
  56int 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 */
 108int 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
 125int 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
 139