Pauli Nieminen | 7a9f0dd | 2010-02-01 19:11:15 +0200 | [diff] [blame^] | 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 | extern 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 = 0; |
| 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); |