drm: add prime helpers

Instead of reimplementing all of the dma_buf functionality in every driver, create helpers drm_prime_import and drm_prime_export that implement them in terms of new, lower-level hook functions: gem_prime_pin: callback when a buffer is created, used to pin buffers into GTT gem_prime_get_sg_table: convert a drm_gem_object to an sg_table for export gem_prime_import_sg_table: convert an sg_table into a drm_gem_object gem_prime_vmap, gem_prime_vunmap: map and unmap an object These hooks are optional; drivers can opt in by using drm_gem_prime_import and drm_gem_prime_export as the .gem_prime_import and .gem_prime_export fields of struct drm_driver. v2: - Drop .begin_cpu_access. None of the drivers this code replaces implemented it. Having it here was a leftover from when I was trying to include i915 in this rework. - Use mutex_lock instead of mutex_lock_interruptible, as these three drivers did. This patch series shouldn't change that behavior. - Rename helpers to gem_prime_get_sg_table and gem_prime_import_sg_table. Rename struct sg_table* variables to 'sgt' for clarity. - Update drm.tmpl for these new hooks. v3: - Pass the vaddr down to the driver. This lets drivers that just call vunmap on the pointer avoid having to store the pointer in their GEM private structures. - Move documentation into a /** DOC */ comment in drm_prime.c and include it in drm.tmpl with a !P line. I tried to use !F lines to include documentation of the individual functions from drmP.h, but the docproc / kernel-doc scripts barf on that file, so hopefully this is good enough for now. - apply refcount fix from commit be8a42ae60addd8b6092535c11b42d099d6470ec ("drm/prime: drop reference on imported dma-buf come from gem") Signed-off-by: Aaron Plattner <aplattner@nvidia.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Signed-off-by: Dave Airlie <airlied@redhat.com>

drm: add prime helpers
Instead of reimplementing all of the dma_buf functionality in every driver, create helpers drm_prime_import and drm_prime_export that implement them in terms of new, lower-level hook functions: gem_prime_pin: callback when a buffer is created, used to pin buffers into GTT gem_prime_get_sg_table: convert a drm_gem_object to an sg_table for export gem_prime_import_sg_table: convert an sg_table into a drm_gem_object gem_prime_vmap, gem_prime_vunmap: map and unmap an object These hooks are optional; drivers can opt in by using drm_gem_prime_import and drm_gem_prime_export as the .gem_prime_import and .gem_prime_export fields of struct drm_driver. v2: - Drop .begin_cpu_access. None of the drivers this code replaces implemented it. Having it here was a leftover from when I was trying to include i915 in this rework. - Use mutex_lock instead of mutex_lock_interruptible, as these three drivers did. This patch series shouldn't change that behavior. - Rename helpers to gem_prime_get_sg_table and gem_prime_import_sg_table. Rename struct sg_table* variables to 'sgt' for clarity. - Update drm.tmpl for these new hooks. v3: - Pass the vaddr down to the driver. This lets drivers that just call vunmap on the pointer avoid having to store the pointer in their GEM private structures. - Move documentation into a /** DOC */ comment in drm_prime.c and include it in drm.tmpl with a !P line. I tried to use !F lines to include documentation of the individual functions from drmP.h, but the docproc / kernel-doc scripts barf on that file, so hopefully this is good enough for now. - apply refcount fix from commit be8a42ae60addd8b6092535c11b42d099d6470ec ("drm/prime: drop reference on imported dma-buf come from gem") Signed-off-by: Aaron Plattner <aplattner@nvidia.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Signed-off-by: Dave Airlie <airlied@redhat.com>
Aaron Plattner · Dave Airlie
1 parent 6504d0d990
Showing 3 changed files with 201 additions and 1 deletions Side-by-side Diff
Documentation/DocBook/drm.tmpl
drivers/gpu/drm/drm_prime.c
include/drm/drmP.h
@@ -743,6 +743,10 @@
           These two operations are mandatory for GEM drivers that support DRM
           PRIME.
         </para>
+        <sect4>
+          <title>DRM PRIME Helper Functions Reference</title>
+!Pdrivers/gpu/drm/drm_prime.c PRIME Helpers
+        </sect4>
       </sect3>
       <sect3 id="drm-gem-objects-mapping">
         <title>GEM Objects Mapping</title>
@@ -53,7 +53,8 @@
  * Self-importing: if userspace is using PRIME as a replacement for flink
  * then it will get a fd->handle request for a GEM object that it created.
  * Drivers should detect this situation and return back the gem object
- * from the dma-buf private.
+ * from the dma-buf private.  Prime will do this automatically for drivers that
+ * use the drm_gem_prime_{import,export} helpers.
  */
  
 struct drm_prime_member {
@@ -62,6 +63,137 @@
 	uint32_t handle;
 };
  
+static struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
+		enum dma_data_direction dir)
+{
+	struct drm_gem_object *obj = attach->dmabuf->priv;
+	struct sg_table *sgt;
+
+	mutex_lock(&obj->dev->struct_mutex);
+
+	sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
+
+	if (!IS_ERR_OR_NULL(sgt))
+		dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir);
+
+	mutex_unlock(&obj->dev->struct_mutex);
+	return sgt;
+}
+
+static void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
+		struct sg_table *sgt, enum dma_data_direction dir)
+{
+	dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
+	sg_free_table(sgt);
+	kfree(sgt);
+}
+
+static void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+
+	if (obj->export_dma_buf == dma_buf) {
+		/* drop the reference on the export fd holds */
+		obj->export_dma_buf = NULL;
+		drm_gem_object_unreference_unlocked(obj);
+	}
+}
+
+static void *drm_gem_dmabuf_vmap(struct dma_buf *dma_buf)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+	struct drm_device *dev = obj->dev;
+
+	return dev->driver->gem_prime_vmap(obj);
+}
+
+static void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+	struct drm_device *dev = obj->dev;
+
+	dev->driver->gem_prime_vunmap(obj, vaddr);
+}
+
+static void *drm_gem_dmabuf_kmap_atomic(struct dma_buf *dma_buf,
+		unsigned long page_num)
+{
+	return NULL;
+}
+
+static void drm_gem_dmabuf_kunmap_atomic(struct dma_buf *dma_buf,
+		unsigned long page_num, void *addr)
+{
+
+}
+static void *drm_gem_dmabuf_kmap(struct dma_buf *dma_buf,
+		unsigned long page_num)
+{
+	return NULL;
+}
+
+static void drm_gem_dmabuf_kunmap(struct dma_buf *dma_buf,
+		unsigned long page_num, void *addr)
+{
+
+}
+
+static int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf,
+		struct vm_area_struct *vma)
+{
+	return -EINVAL;
+}
+
+static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
+	.map_dma_buf = drm_gem_map_dma_buf,
+	.unmap_dma_buf = drm_gem_unmap_dma_buf,
+	.release = drm_gem_dmabuf_release,
+	.kmap = drm_gem_dmabuf_kmap,
+	.kmap_atomic = drm_gem_dmabuf_kmap_atomic,
+	.kunmap = drm_gem_dmabuf_kunmap,
+	.kunmap_atomic = drm_gem_dmabuf_kunmap_atomic,
+	.mmap = drm_gem_dmabuf_mmap,
+	.vmap = drm_gem_dmabuf_vmap,
+	.vunmap = drm_gem_dmabuf_vunmap,
+};
+
+/**
+ * DOC: PRIME Helpers
+ *
+ * Drivers can implement @gem_prime_export and @gem_prime_import in terms of
+ * simpler APIs by using the helper functions @drm_gem_prime_export and
+ * @drm_gem_prime_import.  These functions implement dma-buf support in terms of
+ * five lower-level driver callbacks:
+ *
+ * Export callbacks:
+ *
+ *  - @gem_prime_pin (optional): prepare a GEM object for exporting
+ *
+ *  - @gem_prime_get_sg_table: provide a scatter/gather table of pinned pages
+ *
+ *  - @gem_prime_vmap: vmap a buffer exported by your driver
+ *
+ *  - @gem_prime_vunmap: vunmap a buffer exported by your driver
+ *
+ * Import callback:
+ *
+ *  - @gem_prime_import_sg_table (import): produce a GEM object from another
+ *    driver's scatter/gather table
+ */
+
+struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
+				     struct drm_gem_object *obj, int flags)
+{
+	if (dev->driver->gem_prime_pin) {
+		int ret = dev->driver->gem_prime_pin(obj);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+	return dma_buf_export(obj, &drm_gem_prime_dmabuf_ops, obj->size,
+			      0600);
+}
+EXPORT_SYMBOL(drm_gem_prime_export);
+
 int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 		struct drm_file *file_priv, uint32_t handle, uint32_t flags,
 		int *prime_fd)
@@ -116,6 +248,58 @@
 	return 0;
 }
 EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
+
+struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
+					    struct dma_buf *dma_buf)
+{
+	struct dma_buf_attachment *attach;
+	struct sg_table *sgt;
+	struct drm_gem_object *obj;
+	int ret;
+
+	if (!dev->driver->gem_prime_import_sg_table)
+		return ERR_PTR(-EINVAL);
+
+	if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
+		obj = dma_buf->priv;
+		if (obj->dev == dev) {
+			/*
+			 * Importing dmabuf exported from out own gem increases
+			 * refcount on gem itself instead of f_count of dmabuf.
+			 */
+			drm_gem_object_reference(obj);
+			dma_buf_put(dma_buf);
+			return obj;
+		}
+	}
+
+	attach = dma_buf_attach(dma_buf, dev->dev);
+	if (IS_ERR(attach))
+		return ERR_PTR(PTR_ERR(attach));
+
+	sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
+	if (IS_ERR_OR_NULL(sgt)) {
+		ret = PTR_ERR(sgt);
+		goto fail_detach;
+	}
+
+	obj = dev->driver->gem_prime_import_sg_table(dev, dma_buf->size, sgt);
+	if (IS_ERR(obj)) {
+		ret = PTR_ERR(obj);
+		goto fail_unmap;
+	}
+
+	obj->import_attach = attach;
+
+	return obj;
+
+fail_unmap:
+	dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
+fail_detach:
+	dma_buf_detach(dma_buf, attach);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(drm_gem_prime_import);
  
 int drm_gem_prime_fd_to_handle(struct drm_device *dev,
 		struct drm_file *file_priv, int prime_fd, uint32_t *handle)
@@ -930,6 +930,14 @@
 	/* import dmabuf -> GEM */
 	struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev,
 				struct dma_buf *dma_buf);
+	/* low-level interface used by drm_gem_prime_{import,export} */
+	int (*gem_prime_pin)(struct drm_gem_object *obj);
+	struct sg_table *(*gem_prime_get_sg_table)(struct drm_gem_object *obj);
+	struct drm_gem_object *(*gem_prime_import_sg_table)(
+				struct drm_device *dev, size_t size,
+				struct sg_table *sgt);
+	void *(*gem_prime_vmap)(struct drm_gem_object *obj);
+	void (*gem_prime_vunmap)(struct drm_gem_object *obj, void *vaddr);
  
 	/* vga arb irq handler */
 	void (*vgaarb_irq)(struct drm_device *dev, bool state);
  
@@ -1562,9 +1570,13 @@
 extern int drm_gem_name_info(struct seq_file *m, void *data);
  
  
+extern struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
+		struct drm_gem_object *obj, int flags);
 extern int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 		struct drm_file *file_priv, uint32_t handle, uint32_t flags,
 		int *prime_fd);
+extern struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
+		struct dma_buf *dma_buf);
 extern int drm_gem_prime_fd_to_handle(struct drm_device *dev,
 		struct drm_file *file_priv, int prime_fd, uint32_t *handle);
...	...	@@ -743,6 +743,10 @@
743	743	These two operations are mandatory for GEM drivers that support DRM
744	744	PRIME.
745	745	</para>
	746	+ <sect4>
	747	+ <title>DRM PRIME Helper Functions Reference</title>
	748	+!Pdrivers/gpu/drm/drm_prime.c PRIME Helpers
	749	+ </sect4>
746	750	</sect3>
747	751	<sect3 id="drm-gem-objects-mapping">
748	752	<title>GEM Objects Mapping</title>
...	...	@@ -53,7 +53,8 @@
53	53	* Self-importing: if userspace is using PRIME as a replacement for flink
54	54	* then it will get a fd->handle request for a GEM object that it created.
55	55	* Drivers should detect this situation and return back the gem object
56		- * from the dma-buf private.
	56	+ * from the dma-buf private. Prime will do this automatically for drivers that
	57	+ * use the drm_gem_prime_{import,export} helpers.
57	58	*/
58	59
59	60	struct drm_prime_member {
...	...	@@ -62,6 +63,137 @@
62	63	uint32_t handle;
63	64	};
64	65
	66	+static struct sg_table drm_gem_map_dma_buf(struct dma_buf_attachment attach,
	67	+ enum dma_data_direction dir)
	68	+{
	69	+ struct drm_gem_object *obj = attach->dmabuf->priv;
	70	+ struct sg_table *sgt;
	71	+
	72	+ mutex_lock(&obj->dev->struct_mutex);
	73	+
	74	+ sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
	75	+
	76	+ if (!IS_ERR_OR_NULL(sgt))
	77	+ dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir);
	78	+
	79	+ mutex_unlock(&obj->dev->struct_mutex);
	80	+ return sgt;
	81	+}
	82	+
	83	+static void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
	84	+ struct sg_table *sgt, enum dma_data_direction dir)
	85	+{
	86	+ dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
	87	+ sg_free_table(sgt);
	88	+ kfree(sgt);
	89	+}
	90	+
	91	+static void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
	92	+{
	93	+ struct drm_gem_object *obj = dma_buf->priv;
	94	+
	95	+ if (obj->export_dma_buf == dma_buf) {
	96	+ /* drop the reference on the export fd holds */
	97	+ obj->export_dma_buf = NULL;
	98	+ drm_gem_object_unreference_unlocked(obj);
	99	+ }
	100	+}
	101	+
	102	+static void drm_gem_dmabuf_vmap(struct dma_buf dma_buf)
	103	+{
	104	+ struct drm_gem_object *obj = dma_buf->priv;
	105	+ struct drm_device *dev = obj->dev;
	106	+
	107	+ return dev->driver->gem_prime_vmap(obj);
	108	+}
	109	+
	110	+static void drm_gem_dmabuf_vunmap(struct dma_buf dma_buf, void vaddr)
	111	+{
	112	+ struct drm_gem_object *obj = dma_buf->priv;
	113	+ struct drm_device *dev = obj->dev;
	114	+
	115	+ dev->driver->gem_prime_vunmap(obj, vaddr);
	116	+}
	117	+
	118	+static void drm_gem_dmabuf_kmap_atomic(struct dma_buf dma_buf,
	119	+ unsigned long page_num)
	120	+{
	121	+ return NULL;
	122	+}
	123	+
	124	+static void drm_gem_dmabuf_kunmap_atomic(struct dma_buf *dma_buf,
	125	+ unsigned long page_num, void *addr)
	126	+{
	127	+
	128	+}
	129	+static void drm_gem_dmabuf_kmap(struct dma_buf dma_buf,
	130	+ unsigned long page_num)
	131	+{
	132	+ return NULL;
	133	+}
	134	+
	135	+static void drm_gem_dmabuf_kunmap(struct dma_buf *dma_buf,
	136	+ unsigned long page_num, void *addr)
	137	+{
	138	+
	139	+}
	140	+
	141	+static int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf,
	142	+ struct vm_area_struct *vma)
	143	+{
	144	+ return -EINVAL;
	145	+}
	146	+
	147	+static const struct dma_buf_ops drm_gem_prime_dmabuf_ops = {
	148	+ .map_dma_buf = drm_gem_map_dma_buf,
	149	+ .unmap_dma_buf = drm_gem_unmap_dma_buf,
	150	+ .release = drm_gem_dmabuf_release,
	151	+ .kmap = drm_gem_dmabuf_kmap,
	152	+ .kmap_atomic = drm_gem_dmabuf_kmap_atomic,
	153	+ .kunmap = drm_gem_dmabuf_kunmap,
	154	+ .kunmap_atomic = drm_gem_dmabuf_kunmap_atomic,
	155	+ .mmap = drm_gem_dmabuf_mmap,
	156	+ .vmap = drm_gem_dmabuf_vmap,
	157	+ .vunmap = drm_gem_dmabuf_vunmap,
	158	+};
	159	+
	160	+/**
	161	+ * DOC: PRIME Helpers
	162	+ *
	163	+ * Drivers can implement @gem_prime_export and @gem_prime_import in terms of
	164	+ * simpler APIs by using the helper functions @drm_gem_prime_export and
	165	+ * @drm_gem_prime_import. These functions implement dma-buf support in terms of
	166	+ * five lower-level driver callbacks:
	167	+ *
	168	+ * Export callbacks:
	169	+ *
	170	+ * - @gem_prime_pin (optional): prepare a GEM object for exporting
	171	+ *
	172	+ * - @gem_prime_get_sg_table: provide a scatter/gather table of pinned pages
	173	+ *
	174	+ * - @gem_prime_vmap: vmap a buffer exported by your driver
	175	+ *
	176	+ * - @gem_prime_vunmap: vunmap a buffer exported by your driver
	177	+ *
	178	+ * Import callback:
	179	+ *
	180	+ * - @gem_prime_import_sg_table (import): produce a GEM object from another
	181	+ * driver's scatter/gather table
	182	+ */
	183	+
	184	+struct dma_buf drm_gem_prime_export(struct drm_device dev,
	185	+ struct drm_gem_object *obj, int flags)
	186	+{
	187	+ if (dev->driver->gem_prime_pin) {
	188	+ int ret = dev->driver->gem_prime_pin(obj);
	189	+ if (ret)
	190	+ return ERR_PTR(ret);
	191	+ }
	192	+ return dma_buf_export(obj, &drm_gem_prime_dmabuf_ops, obj->size,
	193	+ 0600);
	194	+}
	195	+EXPORT_SYMBOL(drm_gem_prime_export);
	196	+
65	197	int drm_gem_prime_handle_to_fd(struct drm_device *dev,
66	198	struct drm_file *file_priv, uint32_t handle, uint32_t flags,
67	199	int *prime_fd)
...	...	@@ -116,6 +248,58 @@
116	248	return 0;
117	249	}
118	250	EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
	251	+
	252	+struct drm_gem_object drm_gem_prime_import(struct drm_device dev,
	253	+ struct dma_buf *dma_buf)
	254	+{
	255	+ struct dma_buf_attachment *attach;
	256	+ struct sg_table *sgt;
	257	+ struct drm_gem_object *obj;
	258	+ int ret;
	259	+
	260	+ if (!dev->driver->gem_prime_import_sg_table)
	261	+ return ERR_PTR(-EINVAL);
	262	+
	263	+ if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
	264	+ obj = dma_buf->priv;
	265	+ if (obj->dev == dev) {
	266	+ /*
	267	+ * Importing dmabuf exported from out own gem increases
	268	+ * refcount on gem itself instead of f_count of dmabuf.
	269	+ */
	270	+ drm_gem_object_reference(obj);
	271	+ dma_buf_put(dma_buf);
	272	+ return obj;
	273	+ }
	274	+ }
	275	+
	276	+ attach = dma_buf_attach(dma_buf, dev->dev);
	277	+ if (IS_ERR(attach))
	278	+ return ERR_PTR(PTR_ERR(attach));
	279	+
	280	+ sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
	281	+ if (IS_ERR_OR_NULL(sgt)) {
	282	+ ret = PTR_ERR(sgt);
	283	+ goto fail_detach;
	284	+ }
	285	+
	286	+ obj = dev->driver->gem_prime_import_sg_table(dev, dma_buf->size, sgt);
	287	+ if (IS_ERR(obj)) {
	288	+ ret = PTR_ERR(obj);
	289	+ goto fail_unmap;
	290	+ }
	291	+
	292	+ obj->import_attach = attach;
	293	+
	294	+ return obj;
	295	+
	296	+fail_unmap:
	297	+ dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
	298	+fail_detach:
	299	+ dma_buf_detach(dma_buf, attach);
	300	+ return ERR_PTR(ret);
	301	+}
	302	+EXPORT_SYMBOL(drm_gem_prime_import);
119	303
120	304	int drm_gem_prime_fd_to_handle(struct drm_device *dev,
121	305	struct drm_file file_priv, int prime_fd, uint32_t handle)
...	...	@@ -930,6 +930,14 @@
930	930	/* import dmabuf -> GEM */
931	931	struct drm_gem_object * (gem_prime_import)(struct drm_device dev,
932	932	struct dma_buf *dma_buf);
	933	+ /* low-level interface used by drm_gem_prime_{import,export} */
	934	+ int (gem_prime_pin)(struct drm_gem_object obj);
	935	+ struct sg_table (gem_prime_get_sg_table)(struct drm_gem_object *obj);
	936	+ struct drm_gem_object (gem_prime_import_sg_table)(
	937	+ struct drm_device *dev, size_t size,
	938	+ struct sg_table *sgt);
	939	+ void (gem_prime_vmap)(struct drm_gem_object *obj);
	940	+ void (gem_prime_vunmap)(struct drm_gem_object obj, void *vaddr);
933	941
934	942	/* vga arb irq handler */
935	943	void (vgaarb_irq)(struct drm_device dev, bool state);
936	944
...	...	@@ -1562,9 +1570,13 @@
1562	1570	extern int drm_gem_name_info(struct seq_file m, void data);
1563	1571
1564	1572
	1573	+extern struct dma_buf drm_gem_prime_export(struct drm_device dev,
	1574	+ struct drm_gem_object *obj, int flags);
1565	1575	extern int drm_gem_prime_handle_to_fd(struct drm_device *dev,
1566	1576	struct drm_file *file_priv, uint32_t handle, uint32_t flags,
1567	1577	int *prime_fd);
	1578	+extern struct drm_gem_object drm_gem_prime_import(struct drm_device dev,
	1579	+ struct dma_buf *dma_buf);
1568	1580	extern int drm_gem_prime_fd_to_handle(struct drm_device *dev,
1569	1581	struct drm_file file_priv, int prime_fd, uint32_t handle);
1570	1582