Commit 89177644 authored by Aaron Plattner's avatar Aaron Plattner Committed by Dave Airlie

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 be8a42ae
  ("drm/prime: drop reference on imported dma-buf come from gem")
Signed-off-by: default avatarAaron Plattner <aplattner@nvidia.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent 6504d0d9
......@@ -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>
......
......@@ -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) {
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 @@ struct drm_driver {
/* 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_clients_info(struct seq_file *m, void* data);
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);
......
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