2 * Copyright © 2012 Red Hat
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
24 * Dave Airlie <airlied@redhat.com>
25 * Rob Clark <rob.clark@linaro.org>
29 #include <linux/dma-buf.h>
33 * DMA-BUF/GEM Object references and lifetime overview:
35 * On the export the dma_buf holds a reference to the exporting GEM
36 * object. It takes this reference in handle_to_fd_ioctl, when it
37 * first calls .prime_export and stores the exporting GEM object in
38 * the dma_buf priv. This reference is released when the dma_buf
39 * object goes away in the driver .release function.
41 * On the import the importing GEM object holds a reference to the
42 * dma_buf (which in turn holds a ref to the exporting GEM object).
43 * It takes that reference in the fd_to_handle ioctl.
44 * It calls dma_buf_get, creates an attachment to it and stores the
45 * attachment in the GEM object. When this attachment is destroyed
46 * when the imported object is destroyed, we remove the attachment
47 * and drop the reference to the dma_buf.
49 * Thus the chain of references always flows in one direction
50 * (avoiding loops): importing_gem -> dmabuf -> exporting_gem
52 * Self-importing: if userspace is using PRIME as a replacement for flink
53 * then it will get a fd->handle request for a GEM object that it created.
54 * Drivers should detect this situation and return back the gem object
55 * from the dma-buf private.
58 struct drm_prime_member {
59 struct list_head entry;
60 struct dma_buf *dma_buf;
64 int drm_gem_prime_handle_to_fd(struct drm_device *dev,
65 struct drm_file *file_priv, uint32_t handle, uint32_t flags,
68 struct drm_gem_object *obj;
71 obj = drm_gem_object_lookup(dev, file_priv, handle);
75 mutex_lock(&file_priv->prime.lock);
76 /* re-export the original imported object */
77 if (obj->import_attach) {
78 get_dma_buf(obj->import_attach->dmabuf);
79 *prime_fd = dma_buf_fd(obj->import_attach->dmabuf, flags);
80 drm_gem_object_unreference_unlocked(obj);
81 mutex_unlock(&file_priv->prime.lock);
85 if (obj->export_dma_buf) {
86 get_dma_buf(obj->export_dma_buf);
87 *prime_fd = dma_buf_fd(obj->export_dma_buf, flags);
88 drm_gem_object_unreference_unlocked(obj);
90 buf = dev->driver->gem_prime_export(dev, obj, flags);
92 /* normally the created dma-buf takes ownership of the ref,
93 * but if that fails then drop the ref
95 drm_gem_object_unreference_unlocked(obj);
96 mutex_unlock(&file_priv->prime.lock);
99 obj->export_dma_buf = buf;
100 *prime_fd = dma_buf_fd(buf, flags);
102 mutex_unlock(&file_priv->prime.lock);
105 EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
107 int drm_gem_prime_fd_to_handle(struct drm_device *dev,
108 struct drm_file *file_priv, int prime_fd, uint32_t *handle)
110 struct dma_buf *dma_buf;
111 struct drm_gem_object *obj;
114 dma_buf = dma_buf_get(prime_fd);
116 return PTR_ERR(dma_buf);
118 mutex_lock(&file_priv->prime.lock);
120 ret = drm_prime_lookup_imported_buf_handle(&file_priv->prime,
127 /* never seen this one, need to import */
128 obj = dev->driver->gem_prime_import(dev, dma_buf);
134 ret = drm_gem_handle_create(file_priv, obj, handle);
135 drm_gem_object_unreference_unlocked(obj);
139 ret = drm_prime_add_imported_buf_handle(&file_priv->prime,
144 mutex_unlock(&file_priv->prime.lock);
148 /* hmm, if driver attached, we are relying on the free-object path
149 * to detach.. which seems ok..
151 drm_gem_object_handle_unreference_unlocked(obj);
153 dma_buf_put(dma_buf);
154 mutex_unlock(&file_priv->prime.lock);
157 EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);
159 int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
160 struct drm_file *file_priv)
162 struct drm_prime_handle *args = data;
165 if (!drm_core_check_feature(dev, DRIVER_PRIME))
168 if (!dev->driver->prime_handle_to_fd)
171 /* check flags are valid */
172 if (args->flags & ~DRM_CLOEXEC)
175 /* we only want to pass DRM_CLOEXEC which is == O_CLOEXEC */
176 flags = args->flags & DRM_CLOEXEC;
178 return dev->driver->prime_handle_to_fd(dev, file_priv,
179 args->handle, flags, &args->fd);
182 int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
183 struct drm_file *file_priv)
185 struct drm_prime_handle *args = data;
187 if (!drm_core_check_feature(dev, DRIVER_PRIME))
190 if (!dev->driver->prime_fd_to_handle)
193 return dev->driver->prime_fd_to_handle(dev, file_priv,
194 args->fd, &args->handle);
198 * drm_prime_pages_to_sg
200 * this helper creates an sg table object from a set of pages
201 * the driver is responsible for mapping the pages into the
202 * importers address space
204 struct sg_table *drm_prime_pages_to_sg(struct page **pages, int nr_pages)
206 struct sg_table *sg = NULL;
207 struct scatterlist *iter;
211 sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
215 ret = sg_alloc_table(sg, nr_pages, GFP_KERNEL);
219 for_each_sg(sg->sgl, iter, nr_pages, i)
220 sg_set_page(iter, pages[i], PAGE_SIZE, 0);
227 EXPORT_SYMBOL(drm_prime_pages_to_sg);
229 /* helper function to cleanup a GEM/prime object */
230 void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
232 struct dma_buf_attachment *attach;
233 struct dma_buf *dma_buf;
234 attach = obj->import_attach;
236 dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
237 dma_buf = attach->dmabuf;
238 dma_buf_detach(attach->dmabuf, attach);
239 /* remove the reference */
240 dma_buf_put(dma_buf);
242 EXPORT_SYMBOL(drm_prime_gem_destroy);
244 void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
246 INIT_LIST_HEAD(&prime_fpriv->head);
247 mutex_init(&prime_fpriv->lock);
249 EXPORT_SYMBOL(drm_prime_init_file_private);
251 void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
253 struct drm_prime_member *member, *safe;
254 list_for_each_entry_safe(member, safe, &prime_fpriv->head, entry) {
255 list_del(&member->entry);
259 EXPORT_SYMBOL(drm_prime_destroy_file_private);
261 int drm_prime_add_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle)
263 struct drm_prime_member *member;
265 member = kmalloc(sizeof(*member), GFP_KERNEL);
269 member->dma_buf = dma_buf;
270 member->handle = handle;
271 list_add(&member->entry, &prime_fpriv->head);
274 EXPORT_SYMBOL(drm_prime_add_imported_buf_handle);
276 int drm_prime_lookup_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t *handle)
278 struct drm_prime_member *member;
280 list_for_each_entry(member, &prime_fpriv->head, entry) {
281 if (member->dma_buf == dma_buf) {
282 *handle = member->handle;
288 EXPORT_SYMBOL(drm_prime_lookup_imported_buf_handle);
290 void drm_prime_remove_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf)
292 struct drm_prime_member *member, *safe;
294 mutex_lock(&prime_fpriv->lock);
295 list_for_each_entry_safe(member, safe, &prime_fpriv->head, entry) {
296 if (member->dma_buf == dma_buf) {
297 list_del(&member->entry);
301 mutex_unlock(&prime_fpriv->lock);
303 EXPORT_SYMBOL(drm_prime_remove_imported_buf_handle);