linux/drivers/gpu/drm/drm_buffer.c
<<
>>
Prefs
   1/**************************************************************************
   2 *
   3 * Copyright 2010 Pauli Nieminen.
   4 * All Rights Reserved.
   5 *
   6 * Permission is hereby granted, free of charge, to any person obtaining a
   7 * copy of this software and associated documentation files (the
   8 * "Software"), to deal in the Software without restriction, including
   9 * without limitation the rights to use, copy, modify, merge, publish,
  10 * distribute, sub license, and/or sell copies of the Software, and to
  11 * permit persons to whom the Software is furnished to do so, subject to
  12 * the following conditions:
  13 *
  14 * The above copyright notice and this permission notice (including the
  15 * next paragraph) shall be included in all copies or substantial portions
  16 * of the Software.
  17 *
  18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  21 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  22 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  23 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  24 * USE OR OTHER DEALINGS IN THE SOFTWARE.
  25 *
  26 *
  27 **************************************************************************/
  28/*
  29 * Multipart buffer for coping data which is larger than the page size.
  30 *
  31 * Authors:
  32 * Pauli Nieminen <suokkos-at-gmail-dot-com>
  33 */
  34
  35#include <linux/export.h>
  36#include <drm/drm_buffer.h>
  37
  38/**
  39 * Allocate the drm buffer object.
  40 *
  41 *   buf: Pointer to a pointer where the object is stored.
  42 *   size: The number of bytes to allocate.
  43 */
  44int drm_buffer_alloc(struct drm_buffer **buf, int size)
  45{
  46        int nr_pages = size / PAGE_SIZE + 1;
  47        int idx;
  48
  49        /* Allocating pointer table to end of structure makes drm_buffer
  50         * variable sized */
  51        *buf = kzalloc(sizeof(struct drm_buffer) + nr_pages*sizeof(char *),
  52                        GFP_KERNEL);
  53
  54        if (*buf == NULL) {
  55                DRM_ERROR("Failed to allocate drm buffer object to hold"
  56                                " %d bytes in %d pages.\n",
  57                                size, nr_pages);
  58                return -ENOMEM;
  59        }
  60
  61        (*buf)->size = size;
  62
  63        for (idx = 0; idx < nr_pages; ++idx) {
  64
  65                (*buf)->data[idx] =
  66                        kmalloc(min(PAGE_SIZE, size - idx * PAGE_SIZE),
  67                                GFP_KERNEL);
  68
  69
  70                if ((*buf)->data[idx] == NULL) {
  71                        DRM_ERROR("Failed to allocate %dth page for drm"
  72                                        " buffer with %d bytes and %d pages.\n",
  73                                        idx + 1, size, nr_pages);
  74                        goto error_out;
  75                }
  76
  77        }
  78
  79        return 0;
  80
  81error_out:
  82
  83        /* Only last element can be null pointer so check for it first. */
  84        if ((*buf)->data[idx])
  85                kfree((*buf)->data[idx]);
  86
  87        for (--idx; idx >= 0; --idx)
  88                kfree((*buf)->data[idx]);
  89
  90        kfree(*buf);
  91        return -ENOMEM;
  92}
  93EXPORT_SYMBOL(drm_buffer_alloc);
  94
  95/**
  96 * Copy the user data to the begin of the buffer and reset the processing
  97 * iterator.
  98 *
  99 *   user_data: A pointer the data that is copied to the buffer.
 100 *   size: The Number of bytes to copy.
 101 */
 102int drm_buffer_copy_from_user(struct drm_buffer *buf,
 103                              void __user *user_data, int size)
 104{
 105        int nr_pages = size / PAGE_SIZE + 1;
 106        int idx;
 107
 108        if (size > buf->size) {
 109                DRM_ERROR("Requesting to copy %d bytes to a drm buffer with"
 110                                " %d bytes space\n",
 111                                size, buf->size);
 112                return -EFAULT;
 113        }
 114
 115        for (idx = 0; idx < nr_pages; ++idx) {
 116
 117                if (copy_from_user(buf->data[idx],
 118                        user_data + idx * PAGE_SIZE,
 119                        min(PAGE_SIZE, size - idx * PAGE_SIZE))) {
 120                        DRM_ERROR("Failed to copy user data (%p) to drm buffer"
 121                                        " (%p) %dth page.\n",
 122                                        user_data, buf, idx);
 123                        return -EFAULT;
 124
 125                }
 126        }
 127        buf->iterator = 0;
 128        return 0;
 129}
 130EXPORT_SYMBOL(drm_buffer_copy_from_user);
 131
 132/**
 133 * Free the drm buffer object
 134 */
 135void drm_buffer_free(struct drm_buffer *buf)
 136{
 137
 138        if (buf != NULL) {
 139
 140                int nr_pages = buf->size / PAGE_SIZE + 1;
 141                int idx;
 142                for (idx = 0; idx < nr_pages; ++idx)
 143                        kfree(buf->data[idx]);
 144
 145                kfree(buf);
 146        }
 147}
 148EXPORT_SYMBOL(drm_buffer_free);
 149
 150/**
 151 * Read an object from buffer that may be split to multiple parts. If object
 152 * is not split function just returns the pointer to object in buffer. But in
 153 * case of split object data is copied to given stack object that is suplied
 154 * by caller.
 155 *
 156 * The processing location of the buffer is also advanced to the next byte
 157 * after the object.
 158 *
 159 *   objsize: The size of the objet in bytes.
 160 *   stack_obj: A pointer to a memory location where object can be copied.
 161 */
 162void *drm_buffer_read_object(struct drm_buffer *buf,
 163                int objsize, void *stack_obj)
 164{
 165        int idx = drm_buffer_index(buf);
 166        int page = drm_buffer_page(buf);
 167        void *obj = NULL;
 168
 169        if (idx + objsize <= PAGE_SIZE) {
 170                obj = &buf->data[page][idx];
 171        } else {
 172                /* The object is split which forces copy to temporary object.*/
 173                int beginsz = PAGE_SIZE - idx;
 174                memcpy(stack_obj, &buf->data[page][idx], beginsz);
 175
 176                memcpy(stack_obj + beginsz, &buf->data[page + 1][0],
 177                                objsize - beginsz);
 178
 179                obj = stack_obj;
 180        }
 181
 182        drm_buffer_advance(buf, objsize);
 183        return obj;
 184}
 185EXPORT_SYMBOL(drm_buffer_read_object);
 186