1/* 2 * Framework for buffer objects that can be shared across devices/subsystems. 3 * 4 * Copyright(C) 2011 Linaro Limited. All rights reserved. 5 * Author: Sumit Semwal <sumit.semwal@ti.com> 6 * 7 * Many thanks to linaro-mm-sig list, and specially 8 * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and 9 * Daniel Vetter <daniel@ffwll.ch> for their support in creation and 10 * refining of this idea. 11 * 12 * This program is free software; you can redistribute it and/or modify it 13 * under the terms of the GNU General Public License version 2 as published by 14 * the Free Software Foundation. 15 * 16 * This program is distributed in the hope that it will be useful, but WITHOUT 17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 18 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 19 * more details. 20 * 21 * You should have received a copy of the GNU General Public License along with 22 * this program. If not, see <http://www.gnu.org/licenses/>. 23 */ 24 25#include <linux/fs.h> 26#include <linux/slab.h> 27#include <linux/dma-buf.h> 28#include <linux/anon_inodes.h> 29#include <linux/export.h> 30 31static inline int is_dma_buf_file(struct file *); 32 33static int dma_buf_release(struct inode *inode, struct file *file) 34{ 35 struct dma_buf *dmabuf; 36 37 if (!is_dma_buf_file(file)) 38 return -EINVAL; 39 40 dmabuf = file->private_data; 41 42 dmabuf->ops->release(dmabuf); 43 kfree(dmabuf); 44 return 0; 45} 46 47static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma) 48{ 49 struct dma_buf *dmabuf; 50 51 if (!is_dma_buf_file(file)) 52 return -EINVAL; 53 54 dmabuf = file->private_data; 55 56 /* check for overflowing the buffer's size */ 57 if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) > 58 dmabuf->size >> PAGE_SHIFT) 59 return -EINVAL; 60 61 return dmabuf->ops->mmap(dmabuf, vma); 62} 63 64static const struct file_operations dma_buf_fops = { 65 .release = dma_buf_release, 66 .mmap = dma_buf_mmap_internal, 67}; 68 69/* 70 * is_dma_buf_file - Check if struct file* is associated with dma_buf 71 */ 72static inline int is_dma_buf_file(struct file *file) 73{ 74 return file->f_op == &dma_buf_fops; 75} 76 77/** 78 * dma_buf_export - Creates a new dma_buf, and associates an anon file 79 * with this buffer, so it can be exported. 80 * Also connect the allocator specific data and ops to the buffer. 81 * 82 * @priv: [in] Attach private data of allocator to this buffer 83 * @ops: [in] Attach allocator-defined dma buf ops to the new buffer. 84 * @size: [in] Size of the buffer 85 * @flags: [in] mode flags for the file. 86 * 87 * Returns, on success, a newly created dma_buf object, which wraps the 88 * supplied private data and operations for dma_buf_ops. On either missing 89 * ops, or error in allocating struct dma_buf, will return negative error. 90 * 91 */ 92struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops, 93 size_t size, int flags) 94{ 95 struct dma_buf *dmabuf; 96 struct file *file; 97 98 if (WARN_ON(!priv || !ops 99 || !ops->map_dma_buf 100 || !ops->unmap_dma_buf 101 || !ops->release 102 || !ops->kmap_atomic 103 || !ops->kmap 104 || !ops->mmap)) { 105 return ERR_PTR(-EINVAL); 106 } 107 108 dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL); 109 if (dmabuf == NULL) 110 return ERR_PTR(-ENOMEM); 111 112 dmabuf->priv = priv; 113 dmabuf->ops = ops; 114 dmabuf->size = size; 115 116 file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags); 117 118 dmabuf->file = file; 119 120 mutex_init(&dmabuf->lock); 121 INIT_LIST_HEAD(&dmabuf->attachments); 122 123 return dmabuf; 124} 125EXPORT_SYMBOL_GPL(dma_buf_export); 126 127 128/** 129 * dma_buf_fd - returns a file descriptor for the given dma_buf 130 * @dmabuf: [in] pointer to dma_buf for which fd is required. 131 * @flags: [in] flags to give to fd 132 * 133 * On success, returns an associated 'fd'. Else, returns error. 134 */ 135int dma_buf_fd(struct dma_buf *dmabuf, int flags) 136{ 137 int error, fd; 138 139 if (!dmabuf || !dmabuf->file) 140 return -EINVAL; 141 142 error = get_unused_fd_flags(flags); 143 if (error < 0) 144 return error; 145 fd = error; 146 147 fd_install(fd, dmabuf->file); 148 149 return fd; 150} 151EXPORT_SYMBOL_GPL(dma_buf_fd); 152 153/** 154 * dma_buf_get - returns the dma_buf structure related to an fd 155 * @fd: [in] fd associated with the dma_buf to be returned 156 * 157 * On success, returns the dma_buf structure associated with an fd; uses 158 * file's refcounting done by fget to increase refcount. returns ERR_PTR 159 * otherwise. 160 */ 161struct dma_buf *dma_buf_get(int fd) 162{ 163 struct file *file; 164 165 file = fget(fd); 166 167 if (!file) 168 return ERR_PTR(-EBADF); 169 170 if (!is_dma_buf_file(file)) { 171 fput(file); 172 return ERR_PTR(-EINVAL); 173 } 174 175 return file->private_data; 176} 177EXPORT_SYMBOL_GPL(dma_buf_get); 178 179/** 180 * dma_buf_put - decreases refcount of the buffer 181 * @dmabuf: [in] buffer to reduce refcount of 182 * 183 * Uses file's refcounting done implicitly by fput() 184 */ 185void dma_buf_put(struct dma_buf *dmabuf) 186{ 187 if (WARN_ON(!dmabuf || !dmabuf->file)) 188 return; 189 190 fput(dmabuf->file); 191} 192EXPORT_SYMBOL_GPL(dma_buf_put); 193 194/** 195 * dma_buf_attach - Add the device to dma_buf's attachments list; optionally, 196 * calls attach() of dma_buf_ops to allow device-specific attach functionality 197 * @dmabuf: [in] buffer to attach device to. 198 * @dev: [in] device to be attached. 199 * 200 * Returns struct dma_buf_attachment * for this attachment; may return negative 201 * error codes. 202 * 203 */ 204struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, 205 struct device *dev) 206{ 207 struct dma_buf_attachment *attach; 208 int ret; 209 210 if (WARN_ON(!dmabuf || !dev)) 211 return ERR_PTR(-EINVAL); 212 213 attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL); 214 if (attach == NULL) 215 return ERR_PTR(-ENOMEM); 216 217 attach->dev = dev; 218 attach->dmabuf = dmabuf; 219 220 mutex_lock(&dmabuf->lock); 221 222 if (dmabuf->ops->attach) { 223 ret = dmabuf->ops->attach(dmabuf, dev, attach); 224 if (ret) 225 goto err_attach; 226 } 227 list_add(&attach->node, &dmabuf->attachments); 228 229 mutex_unlock(&dmabuf->lock); 230 return attach; 231 232err_attach: 233 kfree(attach); 234 mutex_unlock(&dmabuf->lock); 235 return ERR_PTR(ret); 236} 237EXPORT_SYMBOL_GPL(dma_buf_attach); 238 239/** 240 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list; 241 * optionally calls detach() of dma_buf_ops for device-specific detach 242 * @dmabuf: [in] buffer to detach from. 243 * @attach: [in] attachment to be detached; is free'd after this call. 244 * 245 */ 246void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) 247{ 248 if (WARN_ON(!dmabuf || !attach)) 249 return; 250 251 mutex_lock(&dmabuf->lock); 252 list_del(&attach->node); 253 if (dmabuf->ops->detach) 254 dmabuf->ops->detach(dmabuf, attach); 255 256 mutex_unlock(&dmabuf->lock); 257 kfree(attach); 258} 259EXPORT_SYMBOL_GPL(dma_buf_detach); 260 261/** 262 * dma_buf_map_attachment - Returns the scatterlist table of the attachment; 263 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the 264 * dma_buf_ops. 265 * @attach: [in] attachment whose scatterlist is to be returned 266 * @direction: [in] direction of DMA transfer 267 * 268 * Returns sg_table containing the scatterlist to be returned; may return NULL 269 * or ERR_PTR. 270 * 271 */ 272struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, 273 enum dma_data_direction direction) 274{ 275 struct sg_table *sg_table = ERR_PTR(-EINVAL); 276 277 might_sleep(); 278 279 if (WARN_ON(!attach || !attach->dmabuf)) 280 return ERR_PTR(-EINVAL); 281 282 sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction); 283 284 return sg_table; 285} 286EXPORT_SYMBOL_GPL(dma_buf_map_attachment); 287 288/** 289 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might 290 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of 291 * dma_buf_ops. 292 * @attach: [in] attachment to unmap buffer from 293 * @sg_table: [in] scatterlist info of the buffer to unmap 294 * @direction: [in] direction of DMA transfer 295 * 296 */ 297void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, 298 struct sg_table *sg_table, 299 enum dma_data_direction direction) 300{ 301 if (WARN_ON(!attach || !attach->dmabuf || !sg_table)) 302 return; 303 304 attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, 305 direction); 306} 307EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment); 308 309 310/** 311 * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the 312 * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific 313 * preparations. Coherency is only guaranteed in the specified range for the 314 * specified access direction. 315 * @dma_buf: [in] buffer to prepare cpu access for. 316 * @start: [in] start of range for cpu access. 317 * @len: [in] length of range for cpu access. 318 * @direction: [in] length of range for cpu access. 319 * 320 * Can return negative error values, returns 0 on success. 321 */ 322int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len, 323 enum dma_data_direction direction) 324{ 325 int ret = 0; 326 327 if (WARN_ON(!dmabuf)) 328 return -EINVAL; 329 330 if (dmabuf->ops->begin_cpu_access) 331 ret = dmabuf->ops->begin_cpu_access(dmabuf, start, len, direction); 332 333 return ret; 334} 335EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access); 336 337/** 338 * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the 339 * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific 340 * actions. Coherency is only guaranteed in the specified range for the 341 * specified access direction. 342 * @dma_buf: [in] buffer to complete cpu access for. 343 * @start: [in] start of range for cpu access. 344 * @len: [in] length of range for cpu access. 345 * @direction: [in] length of range for cpu access. 346 * 347 * This call must always succeed. 348 */ 349void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len, 350 enum dma_data_direction direction) 351{ 352 WARN_ON(!dmabuf); 353 354 if (dmabuf->ops->end_cpu_access) 355 dmabuf->ops->end_cpu_access(dmabuf, start, len, direction); 356} 357EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access); 358 359/** 360 * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address 361 * space. The same restrictions as for kmap_atomic and friends apply. 362 * @dma_buf: [in] buffer to map page from. 363 * @page_num: [in] page in PAGE_SIZE units to map. 364 * 365 * This call must always succeed, any necessary preparations that might fail 366 * need to be done in begin_cpu_access. 367 */ 368void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num) 369{ 370 WARN_ON(!dmabuf); 371 372 return dmabuf->ops->kmap_atomic(dmabuf, page_num); 373} 374EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic); 375 376/** 377 * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic. 378 * @dma_buf: [in] buffer to unmap page from. 379 * @page_num: [in] page in PAGE_SIZE units to unmap. 380 * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap_atomic. 381 * 382 * This call must always succeed. 383 */ 384void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num, 385 void *vaddr) 386{ 387 WARN_ON(!dmabuf); 388 389 if (dmabuf->ops->kunmap_atomic) 390 dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr); 391} 392EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic); 393 394/** 395 * dma_buf_kmap - Map a page of the buffer object into kernel address space. The 396 * same restrictions as for kmap and friends apply. 397 * @dma_buf: [in] buffer to map page from. 398 * @page_num: [in] page in PAGE_SIZE units to map. 399 * 400 * This call must always succeed, any necessary preparations that might fail 401 * need to be done in begin_cpu_access. 402 */ 403void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num) 404{ 405 WARN_ON(!dmabuf); 406 407 return dmabuf->ops->kmap(dmabuf, page_num); 408} 409EXPORT_SYMBOL_GPL(dma_buf_kmap); 410 411/** 412 * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap. 413 * @dma_buf: [in] buffer to unmap page from. 414 * @page_num: [in] page in PAGE_SIZE units to unmap. 415 * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap. 416 * 417 * This call must always succeed. 418 */ 419void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num, 420 void *vaddr) 421{ 422 WARN_ON(!dmabuf); 423 424 if (dmabuf->ops->kunmap) 425 dmabuf->ops->kunmap(dmabuf, page_num, vaddr); 426} 427EXPORT_SYMBOL_GPL(dma_buf_kunmap); 428 429 430/** 431 * dma_buf_mmap - Setup up a userspace mmap with the given vma 432 * @dma_buf: [in] buffer that should back the vma 433 * @vma: [in] vma for the mmap 434 * @pgoff: [in] offset in pages where this mmap should start within the 435 * dma-buf buffer. 436 * 437 * This function adjusts the passed in vma so that it points at the file of the 438 * dma_buf operation. It alsog adjusts the starting pgoff and does bounds 439 * checking on the size of the vma. Then it calls the exporters mmap function to 440 * set up the mapping. 441 * 442 * Can return negative error values, returns 0 on success. 443 */ 444int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, 445 unsigned long pgoff) 446{ 447 if (WARN_ON(!dmabuf || !vma)) 448 return -EINVAL; 449 450 /* check for offset overflow */ 451 if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff) 452 return -EOVERFLOW; 453 454 /* check for overflowing the buffer's size */ 455 if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) > 456 dmabuf->size >> PAGE_SHIFT) 457 return -EINVAL; 458 459 /* readjust the vma */ 460 if (vma->vm_file) 461 fput(vma->vm_file); 462 463 vma->vm_file = dmabuf->file; 464 get_file(vma->vm_file); 465 466 vma->vm_pgoff = pgoff; 467 468 return dmabuf->ops->mmap(dmabuf, vma); 469} 470EXPORT_SYMBOL_GPL(dma_buf_mmap); 471