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@xxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
---
Documentation/DocBook/drm.tmpl | 4 +
drivers/gpu/drm/drm_prime.c | 186 ++++++++++++++++++++++++++++++++++++++++-
include/drm/drmP.h | 12 +++
3 files changed, 201 insertions(+), 1 deletion(-)
diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl
index 4ee2304..ed40576 100644
--- a/Documentation/DocBook/drm.tmpl
+++ b/Documentation/DocBook/drm.tmpl
@@ -743,6 +743,10 @@ char *date;</synopsis>
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>
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 7f12573..366910d 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -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 @@ struct drm_prime_member {
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)
@@ -117,6 +249,58 @@ int drm_gem_prime_handle_to_fd(struct drm_device *dev,
}
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) {
