drivers/gpu/drm/drm_buffer.c

   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 "drm_buffer.h"
  36
  37 /**
  38  * Allocate the drm buffer object.
  39  *
  40  *   buf: Pointer to a pointer where the object is stored.
  41  *   size: The number of bytes to allocate.
  42  */
  43 int drm_buffer_alloc(struct drm_buffer **buf, int size)
  44 {
  45         int nr_pages = size / PAGE_SIZE + 1;
  46         int idx;
  47
  48         /* Allocating pointer table to end of structure makes drm_buffer
  49          * variable sized */
  50         *buf = kzalloc(sizeof(struct drm_buffer) + nr_pages*sizeof(char *),
  51                         GFP_KERNEL);
  52
  53         if (*buf == NULL) {
  54                 DRM_ERROR("Failed to allocate drm buffer object to hold"
  55                                 " %d bytes in %d pages.\n",
  56                                 size, nr_pages);
  57                 return -ENOMEM;
  58         }
  59
  60         (*buf)->size = size;
  61
  62         for (idx = 0; idx < nr_pages; ++idx) {
  63
  64                 (*buf)->data[idx] =
  65                         kmalloc(min(PAGE_SIZE, size - idx * PAGE_SIZE),
  66                                 GFP_KERNEL);
  67
  68
  69                 if ((*buf)->data[idx] == NULL) {
  70                         DRM_ERROR("Failed to allocate %dth page for drm"
  71                                         " buffer with %d bytes and %d pages.\n",
  72                                         idx + 1, size, nr_pages);
  73                         goto error_out;
  74                 }
  75
  76         }
  77
  78         return 0;
  79
  80 error_out:
  81
  82         /* Only last element can be null pointer so check for it first. */
  83         if ((*buf)->data[idx])
  84                 kfree((*buf)->data[idx]);
  85
  86         for (--idx; idx >= 0; --idx)
  87                 kfree((*buf)->data[idx]);
  88
  89         kfree(*buf);
  90         return -ENOMEM;
  91 }
  92 EXPORT_SYMBOL(drm_buffer_alloc);
  93
  94 /**
  95  * Copy the user data to the begin of the buffer and reset the processing
  96  * iterator.
  97  *
  98  *   user_data: A pointer the data that is copied to the buffer.
  99  *   size: The Number of bytes to copy.
 100  */
 101 int drm_buffer_copy_from_user(struct drm_buffer *buf,
 102                               void __user *user_data, int size)
 103 {
 104         int nr_pages = size / PAGE_SIZE + 1;
 105         int idx;
 106
 107         if (size > buf->size) {
 108                 DRM_ERROR("Requesting to copy %d bytes to a drm buffer with"
 109                                 " %d bytes space\n",
 110                                 size, buf->size);
 111                 return -EFAULT;
 112         }
 113
 114         for (idx = 0; idx < nr_pages; ++idx) {
 115
 116                 if (DRM_COPY_FROM_USER(buf->data[idx],
 117                         user_data + idx * PAGE_SIZE,
 118                         min(PAGE_SIZE, size - idx * PAGE_SIZE))) {
 119                         DRM_ERROR("Failed to copy user data (%p) to drm buffer"
 120                                         " (%p) %dth page.\n",
 121                                         user_data, buf, idx);
 122                         return -EFAULT;
 123
 124                 }
 125         }
 126         buf->iterator = 0;
 127         return 0;
 128 }
 129 EXPORT_SYMBOL(drm_buffer_copy_from_user);
 130
 131 /**
 132  * Free the drm buffer object
 133  */
 134 void drm_buffer_free(struct drm_buffer *buf)
 135 {
 136
 137         if (buf != NULL) {
 138
 139                 int nr_pages = buf->size / PAGE_SIZE + 1;
 140                 int idx;
 141                 for (idx = 0; idx < nr_pages; ++idx)
 142                         kfree(buf->data[idx]);
 143
 144                 kfree(buf);
 145         }
 146 }
 147 EXPORT_SYMBOL(drm_buffer_free);
 148
 149 /**
 150  * Read an object from buffer that may be split to multiple parts. If object
 151  * is not split function just returns the pointer to object in buffer. But in
 152  * case of split object data is copied to given stack object that is suplied
 153  * by caller.
 154  *
 155  * The processing location of the buffer is also advanced to the next byte
 156  * after the object.
 157  *
 158  *   objsize: The size of the objet in bytes.
 159  *   stack_obj: A pointer to a memory location where object can be copied.
 160  */
 161 void *drm_buffer_read_object(struct drm_buffer *buf,
 162                 int objsize, void *stack_obj)
 163 {
 164         int idx = drm_buffer_index(buf);
 165         int page = drm_buffer_page(buf);
 166         void *obj = NULL;
 167
 168         if (idx + objsize <= PAGE_SIZE) {
 169                 obj = &buf->data[page][idx];
 170         } else {
 171                 /* The object is split which forces copy to temporary object.*/
 172                 int beginsz = PAGE_SIZE - idx;
 173                 memcpy(stack_obj, &buf->data[page][idx], beginsz);
 174
 175                 memcpy(stack_obj + beginsz, &buf->data[page + 1][0],
 176                                 objsize - beginsz);
 177
 178                 obj = stack_obj;
 179         }
 180
 181         drm_buffer_advance(buf, objsize);
 182         return obj;
 183 }
 184 EXPORT_SYMBOL(drm_buffer_read_object);