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caab277b | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
d15bd7ee SS |
2 | /* |
3 | * Header file for dma buffer sharing framework. | |
4 | * | |
5 | * Copyright(C) 2011 Linaro Limited. All rights reserved. | |
6 | * Author: Sumit Semwal <sumit.semwal@ti.com> | |
7 | * | |
8 | * Many thanks to linaro-mm-sig list, and specially | |
9 | * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and | |
10 | * Daniel Vetter <daniel@ffwll.ch> for their support in creation and | |
11 | * refining of this idea. | |
d15bd7ee SS |
12 | */ |
13 | #ifndef __DMA_BUF_H__ | |
14 | #define __DMA_BUF_H__ | |
15 | ||
16 | #include <linux/file.h> | |
17 | #include <linux/err.h> | |
d15bd7ee SS |
18 | #include <linux/scatterlist.h> |
19 | #include <linux/list.h> | |
20 | #include <linux/dma-mapping.h> | |
f9a24d1a | 21 | #include <linux/fs.h> |
f54d1867 | 22 | #include <linux/dma-fence.h> |
9b495a58 | 23 | #include <linux/wait.h> |
d15bd7ee | 24 | |
313162d0 | 25 | struct device; |
d15bd7ee SS |
26 | struct dma_buf; |
27 | struct dma_buf_attachment; | |
28 | ||
29 | /** | |
30 | * struct dma_buf_ops - operations possible on struct dma_buf | |
09ea0dfb | 31 | * @map_atomic: [optional] maps a page from the buffer into kernel address |
f9b67f00 LG |
32 | * space, users may not block until the subsequent unmap call. |
33 | * This callback must not sleep. | |
34 | * @unmap_atomic: [optional] unmaps a atomically mapped page from the buffer. | |
35 | * This Callback must not sleep. | |
09ea0dfb | 36 | * @map: [optional] maps a page from the buffer into kernel address space. |
f9b67f00 | 37 | * @unmap: [optional] unmaps a page from the buffer. |
12c4727e SS |
38 | * @vmap: [optional] creates a virtual mapping for the buffer into kernel |
39 | * address space. Same restrictions as for vmap and friends apply. | |
40 | * @vunmap: [optional] unmaps a vmap from the buffer | |
d15bd7ee SS |
41 | */ |
42 | struct dma_buf_ops { | |
2904a8c1 DV |
43 | /** |
44 | * @attach: | |
45 | * | |
46 | * This is called from dma_buf_attach() to make sure that a given | |
a19741e5 CK |
47 | * &dma_buf_attachment.dev can access the provided &dma_buf. Exporters |
48 | * which support buffer objects in special locations like VRAM or | |
49 | * device-specific carveout areas should check whether the buffer could | |
50 | * be move to system memory (or directly accessed by the provided | |
51 | * device), and otherwise need to fail the attach operation. | |
2904a8c1 DV |
52 | * |
53 | * The exporter should also in general check whether the current | |
54 | * allocation fullfills the DMA constraints of the new device. If this | |
55 | * is not the case, and the allocation cannot be moved, it should also | |
56 | * fail the attach operation. | |
57 | * | |
e9b4d7b5 DV |
58 | * Any exporter-private housekeeping data can be stored in the |
59 | * &dma_buf_attachment.priv pointer. | |
2904a8c1 DV |
60 | * |
61 | * This callback is optional. | |
62 | * | |
63 | * Returns: | |
64 | * | |
65 | * 0 on success, negative error code on failure. It might return -EBUSY | |
66 | * to signal that backing storage is already allocated and incompatible | |
67 | * with the requirements of requesting device. | |
68 | */ | |
a19741e5 | 69 | int (*attach)(struct dma_buf *, struct dma_buf_attachment *); |
d15bd7ee | 70 | |
2904a8c1 DV |
71 | /** |
72 | * @detach: | |
73 | * | |
74 | * This is called by dma_buf_detach() to release a &dma_buf_attachment. | |
75 | * Provided so that exporters can clean up any housekeeping for an | |
76 | * &dma_buf_attachment. | |
77 | * | |
78 | * This callback is optional. | |
79 | */ | |
d15bd7ee SS |
80 | void (*detach)(struct dma_buf *, struct dma_buf_attachment *); |
81 | ||
2904a8c1 DV |
82 | /** |
83 | * @map_dma_buf: | |
84 | * | |
85 | * This is called by dma_buf_map_attachment() and is used to map a | |
86 | * shared &dma_buf into device address space, and it is mandatory. It | |
87 | * can only be called if @attach has been called successfully. This | |
88 | * essentially pins the DMA buffer into place, and it cannot be moved | |
89 | * any more | |
90 | * | |
91 | * This call may sleep, e.g. when the backing storage first needs to be | |
92 | * allocated, or moved to a location suitable for all currently attached | |
93 | * devices. | |
94 | * | |
95 | * Note that any specific buffer attributes required for this function | |
96 | * should get added to device_dma_parameters accessible via | |
e9b4d7b5 | 97 | * &device.dma_params from the &dma_buf_attachment. The @attach callback |
2904a8c1 DV |
98 | * should also check these constraints. |
99 | * | |
100 | * If this is being called for the first time, the exporter can now | |
101 | * choose to scan through the list of attachments for this buffer, | |
102 | * collate the requirements of the attached devices, and choose an | |
103 | * appropriate backing storage for the buffer. | |
104 | * | |
105 | * Based on enum dma_data_direction, it might be possible to have | |
106 | * multiple users accessing at the same time (for reading, maybe), or | |
107 | * any other kind of sharing that the exporter might wish to make | |
108 | * available to buffer-users. | |
109 | * | |
110 | * Returns: | |
111 | * | |
112 | * A &sg_table scatter list of or the backing storage of the DMA buffer, | |
113 | * already mapped into the device address space of the &device attached | |
114 | * with the provided &dma_buf_attachment. | |
115 | * | |
116 | * On failure, returns a negative error value wrapped into a pointer. | |
117 | * May also return -EINTR when a signal was received while being | |
118 | * blocked. | |
d15bd7ee SS |
119 | */ |
120 | struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *, | |
2904a8c1 DV |
121 | enum dma_data_direction); |
122 | /** | |
123 | * @unmap_dma_buf: | |
124 | * | |
125 | * This is called by dma_buf_unmap_attachment() and should unmap and | |
126 | * release the &sg_table allocated in @map_dma_buf, and it is mandatory. | |
127 | * It should also unpin the backing storage if this is the last mapping | |
128 | * of the DMA buffer, it the exporter supports backing storage | |
129 | * migration. | |
130 | */ | |
d15bd7ee | 131 | void (*unmap_dma_buf)(struct dma_buf_attachment *, |
2904a8c1 DV |
132 | struct sg_table *, |
133 | enum dma_data_direction); | |
134 | ||
d15bd7ee SS |
135 | /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY |
136 | * if the call would block. | |
137 | */ | |
138 | ||
2904a8c1 DV |
139 | /** |
140 | * @release: | |
141 | * | |
142 | * Called after the last dma_buf_put to release the &dma_buf, and | |
143 | * mandatory. | |
144 | */ | |
d15bd7ee SS |
145 | void (*release)(struct dma_buf *); |
146 | ||
0959a168 DV |
147 | /** |
148 | * @begin_cpu_access: | |
149 | * | |
150 | * This is called from dma_buf_begin_cpu_access() and allows the | |
151 | * exporter to ensure that the memory is actually available for cpu | |
152 | * access - the exporter might need to allocate or swap-in and pin the | |
153 | * backing storage. The exporter also needs to ensure that cpu access is | |
154 | * coherent for the access direction. The direction can be used by the | |
155 | * exporter to optimize the cache flushing, i.e. access with a different | |
156 | * direction (read instead of write) might return stale or even bogus | |
157 | * data (e.g. when the exporter needs to copy the data to temporary | |
158 | * storage). | |
159 | * | |
160 | * This callback is optional. | |
161 | * | |
162 | * FIXME: This is both called through the DMA_BUF_IOCTL_SYNC command | |
163 | * from userspace (where storage shouldn't be pinned to avoid handing | |
164 | * de-factor mlock rights to userspace) and for the kernel-internal | |
165 | * users of the various kmap interfaces, where the backing storage must | |
166 | * be pinned to guarantee that the atomic kmap calls can succeed. Since | |
167 | * there's no in-kernel users of the kmap interfaces yet this isn't a | |
168 | * real problem. | |
169 | * | |
170 | * Returns: | |
171 | * | |
172 | * 0 on success or a negative error code on failure. This can for | |
173 | * example fail when the backing storage can't be allocated. Can also | |
174 | * return -ERESTARTSYS or -EINTR when the call has been interrupted and | |
175 | * needs to be restarted. | |
176 | */ | |
831e9da7 | 177 | int (*begin_cpu_access)(struct dma_buf *, enum dma_data_direction); |
0959a168 DV |
178 | |
179 | /** | |
180 | * @end_cpu_access: | |
181 | * | |
182 | * This is called from dma_buf_end_cpu_access() when the importer is | |
183 | * done accessing the CPU. The exporter can use this to flush caches and | |
184 | * unpin any resources pinned in @begin_cpu_access. | |
185 | * The result of any dma_buf kmap calls after end_cpu_access is | |
186 | * undefined. | |
187 | * | |
188 | * This callback is optional. | |
189 | * | |
190 | * Returns: | |
191 | * | |
192 | * 0 on success or a negative error code on failure. Can return | |
193 | * -ERESTARTSYS or -EINTR when the call has been interrupted and needs | |
194 | * to be restarted. | |
195 | */ | |
18b862dc | 196 | int (*end_cpu_access)(struct dma_buf *, enum dma_data_direction); |
f9b67f00 LG |
197 | void *(*map)(struct dma_buf *, unsigned long); |
198 | void (*unmap)(struct dma_buf *, unsigned long, void *); | |
4c78513e | 199 | |
0959a168 DV |
200 | /** |
201 | * @mmap: | |
202 | * | |
203 | * This callback is used by the dma_buf_mmap() function | |
204 | * | |
205 | * Note that the mapping needs to be incoherent, userspace is expected | |
206 | * to braket CPU access using the DMA_BUF_IOCTL_SYNC interface. | |
207 | * | |
208 | * Because dma-buf buffers have invariant size over their lifetime, the | |
209 | * dma-buf core checks whether a vma is too large and rejects such | |
210 | * mappings. The exporter hence does not need to duplicate this check. | |
211 | * Drivers do not need to check this themselves. | |
212 | * | |
213 | * If an exporter needs to manually flush caches and hence needs to fake | |
214 | * coherency for mmap support, it needs to be able to zap all the ptes | |
215 | * pointing at the backing storage. Now linux mm needs a struct | |
216 | * address_space associated with the struct file stored in vma->vm_file | |
217 | * to do that with the function unmap_mapping_range. But the dma_buf | |
218 | * framework only backs every dma_buf fd with the anon_file struct file, | |
219 | * i.e. all dma_bufs share the same file. | |
220 | * | |
221 | * Hence exporters need to setup their own file (and address_space) | |
222 | * association by setting vma->vm_file and adjusting vma->vm_pgoff in | |
223 | * the dma_buf mmap callback. In the specific case of a gem driver the | |
224 | * exporter could use the shmem file already provided by gem (and set | |
225 | * vm_pgoff = 0). Exporters can then zap ptes by unmapping the | |
226 | * corresponding range of the struct address_space associated with their | |
227 | * own file. | |
228 | * | |
229 | * This callback is optional. | |
230 | * | |
231 | * Returns: | |
232 | * | |
233 | * 0 on success or a negative error code on failure. | |
234 | */ | |
4c78513e | 235 | int (*mmap)(struct dma_buf *, struct vm_area_struct *vma); |
98f86c9e DA |
236 | |
237 | void *(*vmap)(struct dma_buf *); | |
238 | void (*vunmap)(struct dma_buf *, void *vaddr); | |
d15bd7ee SS |
239 | }; |
240 | ||
241 | /** | |
242 | * struct dma_buf - shared buffer object | |
243 | * @size: size of the buffer | |
244 | * @file: file pointer used for sharing buffers across, and for refcounting. | |
245 | * @attachments: list of dma_buf_attachment that denotes all devices attached. | |
246 | * @ops: dma_buf_ops associated with this buffer object. | |
e2082e3a RC |
247 | * @lock: used internally to serialize list manipulation, attach/detach and vmap/unmap |
248 | * @vmapping_counter: used internally to refcnt the vmaps | |
249 | * @vmap_ptr: the current vmap ptr if vmapping_counter > 0 | |
78df9695 | 250 | * @exp_name: name of the exporter; useful for debugging. |
9abdffe2 SS |
251 | * @owner: pointer to exporter module; used for refcounting when exporter is a |
252 | * kernel module. | |
b89e3563 | 253 | * @list_node: node for dma_buf accounting and debugging. |
d15bd7ee | 254 | * @priv: exporter specific private data for this buffer object. |
3aac4502 | 255 | * @resv: reservation object linked to this dma-buf |
e2082e3a RC |
256 | * @poll: for userspace poll support |
257 | * @cb_excl: for userspace poll support | |
258 | * @cb_shared: for userspace poll support | |
2904a8c1 DV |
259 | * |
260 | * This represents a shared buffer, created by calling dma_buf_export(). The | |
261 | * userspace representation is a normal file descriptor, which can be created by | |
262 | * calling dma_buf_fd(). | |
263 | * | |
264 | * Shared dma buffers are reference counted using dma_buf_put() and | |
265 | * get_dma_buf(). | |
266 | * | |
f641d3b5 | 267 | * Device DMA access is handled by the separate &struct dma_buf_attachment. |
d15bd7ee SS |
268 | */ |
269 | struct dma_buf { | |
270 | size_t size; | |
271 | struct file *file; | |
272 | struct list_head attachments; | |
273 | const struct dma_buf_ops *ops; | |
d15bd7ee | 274 | struct mutex lock; |
f00b4dad DV |
275 | unsigned vmapping_counter; |
276 | void *vmap_ptr; | |
78df9695 | 277 | const char *exp_name; |
9abdffe2 | 278 | struct module *owner; |
b89e3563 | 279 | struct list_head list_node; |
d15bd7ee | 280 | void *priv; |
3aac4502 | 281 | struct reservation_object *resv; |
9b495a58 ML |
282 | |
283 | /* poll support */ | |
284 | wait_queue_head_t poll; | |
285 | ||
286 | struct dma_buf_poll_cb_t { | |
f54d1867 | 287 | struct dma_fence_cb cb; |
9b495a58 ML |
288 | wait_queue_head_t *poll; |
289 | ||
01e5d556 | 290 | __poll_t active; |
9b495a58 | 291 | } cb_excl, cb_shared; |
d15bd7ee SS |
292 | }; |
293 | ||
294 | /** | |
295 | * struct dma_buf_attachment - holds device-buffer attachment data | |
296 | * @dmabuf: buffer for this attachment. | |
297 | * @dev: device attached to the buffer. | |
298 | * @node: list of dma_buf_attachment. | |
299 | * @priv: exporter specific attachment data. | |
300 | * | |
301 | * This structure holds the attachment information between the dma_buf buffer | |
302 | * and its user device(s). The list contains one attachment struct per device | |
303 | * attached to the buffer. | |
2904a8c1 DV |
304 | * |
305 | * An attachment is created by calling dma_buf_attach(), and released again by | |
306 | * calling dma_buf_detach(). The DMA mapping itself needed to initiate a | |
307 | * transfer is created by dma_buf_map_attachment() and freed again by calling | |
308 | * dma_buf_unmap_attachment(). | |
d15bd7ee SS |
309 | */ |
310 | struct dma_buf_attachment { | |
311 | struct dma_buf *dmabuf; | |
312 | struct device *dev; | |
313 | struct list_head node; | |
314 | void *priv; | |
315 | }; | |
316 | ||
d8fbe341 SS |
317 | /** |
318 | * struct dma_buf_export_info - holds information needed to export a dma_buf | |
9abdffe2 SS |
319 | * @exp_name: name of the exporter - useful for debugging. |
320 | * @owner: pointer to exporter module - used for refcounting kernel module | |
d8fbe341 SS |
321 | * @ops: Attach allocator-defined dma buf ops to the new buffer |
322 | * @size: Size of the buffer | |
323 | * @flags: mode flags for the file | |
324 | * @resv: reservation-object, NULL to allocate default one | |
325 | * @priv: Attach private data of allocator to this buffer | |
326 | * | |
327 | * This structure holds the information required to export the buffer. Used | |
328 | * with dma_buf_export() only. | |
329 | */ | |
330 | struct dma_buf_export_info { | |
331 | const char *exp_name; | |
9abdffe2 | 332 | struct module *owner; |
d8fbe341 SS |
333 | const struct dma_buf_ops *ops; |
334 | size_t size; | |
335 | int flags; | |
336 | struct reservation_object *resv; | |
337 | void *priv; | |
338 | }; | |
339 | ||
340 | /** | |
2904a8c1 | 341 | * DEFINE_DMA_BUF_EXPORT_INFO - helper macro for exporters |
e2082e3a | 342 | * @name: export-info name |
2904a8c1 | 343 | * |
f641d3b5 | 344 | * DEFINE_DMA_BUF_EXPORT_INFO macro defines the &struct dma_buf_export_info, |
2904a8c1 | 345 | * zeroes it out and pre-populates exp_name in it. |
d8fbe341 | 346 | */ |
e2082e3a RC |
347 | #define DEFINE_DMA_BUF_EXPORT_INFO(name) \ |
348 | struct dma_buf_export_info name = { .exp_name = KBUILD_MODNAME, \ | |
9abdffe2 | 349 | .owner = THIS_MODULE } |
d8fbe341 | 350 | |
f9a24d1a RC |
351 | /** |
352 | * get_dma_buf - convenience wrapper for get_file. | |
353 | * @dmabuf: [in] pointer to dma_buf | |
354 | * | |
355 | * Increments the reference count on the dma-buf, needed in case of drivers | |
356 | * that either need to create additional references to the dmabuf on the | |
357 | * kernel side. For example, an exporter that needs to keep a dmabuf ptr | |
358 | * so that subsequent exports don't create a new dmabuf. | |
359 | */ | |
360 | static inline void get_dma_buf(struct dma_buf *dmabuf) | |
361 | { | |
362 | get_file(dmabuf->file); | |
363 | } | |
364 | ||
d15bd7ee SS |
365 | struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, |
366 | struct device *dev); | |
367 | void dma_buf_detach(struct dma_buf *dmabuf, | |
368 | struct dma_buf_attachment *dmabuf_attach); | |
78df9695 | 369 | |
d8fbe341 | 370 | struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info); |
78df9695 | 371 | |
55c1c4ca | 372 | int dma_buf_fd(struct dma_buf *dmabuf, int flags); |
d15bd7ee SS |
373 | struct dma_buf *dma_buf_get(int fd); |
374 | void dma_buf_put(struct dma_buf *dmabuf); | |
375 | ||
376 | struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *, | |
377 | enum dma_data_direction); | |
33ea2dcb SS |
378 | void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *, |
379 | enum dma_data_direction); | |
831e9da7 | 380 | int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, |
fc13020e | 381 | enum dma_data_direction dir); |
18b862dc CW |
382 | int dma_buf_end_cpu_access(struct dma_buf *dma_buf, |
383 | enum dma_data_direction dir); | |
fc13020e DV |
384 | void *dma_buf_kmap(struct dma_buf *, unsigned long); |
385 | void dma_buf_kunmap(struct dma_buf *, unsigned long, void *); | |
4c78513e DV |
386 | |
387 | int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, | |
388 | unsigned long); | |
98f86c9e DA |
389 | void *dma_buf_vmap(struct dma_buf *); |
390 | void dma_buf_vunmap(struct dma_buf *, void *vaddr); | |
d15bd7ee | 391 | #endif /* __DMA_BUF_H__ */ |