Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1065 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
new file mode 100644
index 000000000..eb09e8604
--- /dev/null
+++ b/drivers/gpu/drm/drm_prime.c
@@ -0,0 +1,1065 @@
+/*
+ * Copyright © 2012 Red Hat
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *      Dave Airlie <airlied@redhat.com>
+ *      Rob Clark <rob.clark@linaro.org>
+ *
+ */
+
+#include <linux/export.h>
+#include <linux/dma-buf.h>
+#include <linux/rbtree.h>
+#include <linux/module.h>
+
+#include <drm/drm.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_file.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem.h>
+#include <drm/drm_prime.h>
+
+#include "drm_internal.h"
+
+MODULE_IMPORT_NS(DMA_BUF);
+
+/**
+ * DOC: overview and lifetime rules
+ *
+ * Similar to GEM global names, PRIME file descriptors are also used to share
+ * buffer objects across processes. They offer additional security: as file
+ * descriptors must be explicitly sent over UNIX domain sockets to be shared
+ * between applications, they can't be guessed like the globally unique GEM
+ * names.
+ *
+ * Drivers that support the PRIME API implement the
+ * &drm_driver.prime_handle_to_fd and &drm_driver.prime_fd_to_handle operations.
+ * GEM based drivers must use drm_gem_prime_handle_to_fd() and
+ * drm_gem_prime_fd_to_handle() to implement these. For GEM based drivers the
+ * actual driver interfaces is provided through the &drm_gem_object_funcs.export
+ * and &drm_driver.gem_prime_import hooks.
+ *
+ * &dma_buf_ops implementations for GEM drivers are all individually exported
+ * for drivers which need to overwrite or reimplement some of them.
+ *
+ * Reference Counting for GEM Drivers
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * On the export the &dma_buf holds a reference to the exported buffer object,
+ * usually a &drm_gem_object. It takes this reference in the PRIME_HANDLE_TO_FD
+ * IOCTL, when it first calls &drm_gem_object_funcs.export
+ * and stores the exporting GEM object in the &dma_buf.priv field. This
+ * reference needs to be released when the final reference to the &dma_buf
+ * itself is dropped and its &dma_buf_ops.release function is called.  For
+ * GEM-based drivers, the &dma_buf should be exported using
+ * drm_gem_dmabuf_export() and then released by drm_gem_dmabuf_release().
+ *
+ * Thus the chain of references always flows in one direction, avoiding loops:
+ * importing GEM object -> dma-buf -> exported GEM bo. A further complication
+ * are the lookup caches for import and export. These are required to guarantee
+ * that any given object will always have only one unique userspace handle. This
+ * is required to allow userspace to detect duplicated imports, since some GEM
+ * drivers do fail command submissions if a given buffer object is listed more
+ * than once. These import and export caches in &drm_prime_file_private only
+ * retain a weak reference, which is cleaned up when the corresponding object is
+ * released.
+ *
+ * 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 underlying object from the
+ * dma-buf private. For GEM based drivers this is handled in
+ * drm_gem_prime_import() already.
+ */
+
+struct drm_prime_member {
+	struct dma_buf *dma_buf;
+	uint32_t handle;
+
+	struct rb_node dmabuf_rb;
+	struct rb_node handle_rb;
+};
+
+static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv,
+				    struct dma_buf *dma_buf, uint32_t handle)
+{
+	struct drm_prime_member *member;
+	struct rb_node **p, *rb;
+
+	member = kmalloc(sizeof(*member), GFP_KERNEL);
+	if (!member)
+		return -ENOMEM;
+
+	get_dma_buf(dma_buf);
+	member->dma_buf = dma_buf;
+	member->handle = handle;
+
+	rb = NULL;
+	p = &prime_fpriv->dmabufs.rb_node;
+	while (*p) {
+		struct drm_prime_member *pos;
+
+		rb = *p;
+		pos = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
+		if (dma_buf > pos->dma_buf)
+			p = &rb->rb_right;
+		else
+			p = &rb->rb_left;
+	}
+	rb_link_node(&member->dmabuf_rb, rb, p);
+	rb_insert_color(&member->dmabuf_rb, &prime_fpriv->dmabufs);
+
+	rb = NULL;
+	p = &prime_fpriv->handles.rb_node;
+	while (*p) {
+		struct drm_prime_member *pos;
+
+		rb = *p;
+		pos = rb_entry(rb, struct drm_prime_member, handle_rb);
+		if (handle > pos->handle)
+			p = &rb->rb_right;
+		else
+			p = &rb->rb_left;
+	}
+	rb_link_node(&member->handle_rb, rb, p);
+	rb_insert_color(&member->handle_rb, &prime_fpriv->handles);
+
+	return 0;
+}
+
+static struct dma_buf *drm_prime_lookup_buf_by_handle(struct drm_prime_file_private *prime_fpriv,
+						      uint32_t handle)
+{
+	struct rb_node *rb;
+
+	rb = prime_fpriv->handles.rb_node;
+	while (rb) {
+		struct drm_prime_member *member;
+
+		member = rb_entry(rb, struct drm_prime_member, handle_rb);
+		if (member->handle == handle)
+			return member->dma_buf;
+		else if (member->handle < handle)
+			rb = rb->rb_right;
+		else
+			rb = rb->rb_left;
+	}
+
+	return NULL;
+}
+
+static int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv,
+				       struct dma_buf *dma_buf,
+				       uint32_t *handle)
+{
+	struct rb_node *rb;
+
+	rb = prime_fpriv->dmabufs.rb_node;
+	while (rb) {
+		struct drm_prime_member *member;
+
+		member = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
+		if (member->dma_buf == dma_buf) {
+			*handle = member->handle;
+			return 0;
+		} else if (member->dma_buf < dma_buf) {
+			rb = rb->rb_right;
+		} else {
+			rb = rb->rb_left;
+		}
+	}
+
+	return -ENOENT;
+}
+
+void drm_prime_remove_buf_handle(struct drm_prime_file_private *prime_fpriv,
+				 uint32_t handle)
+{
+	struct rb_node *rb;
+
+	mutex_lock(&prime_fpriv->lock);
+
+	rb = prime_fpriv->handles.rb_node;
+	while (rb) {
+		struct drm_prime_member *member;
+
+		member = rb_entry(rb, struct drm_prime_member, handle_rb);
+		if (member->handle == handle) {
+			rb_erase(&member->handle_rb, &prime_fpriv->handles);
+			rb_erase(&member->dmabuf_rb, &prime_fpriv->dmabufs);
+
+			dma_buf_put(member->dma_buf);
+			kfree(member);
+			break;
+		} else if (member->handle < handle) {
+			rb = rb->rb_right;
+		} else {
+			rb = rb->rb_left;
+		}
+	}
+
+	mutex_unlock(&prime_fpriv->lock);
+}
+
+void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
+{
+	mutex_init(&prime_fpriv->lock);
+	prime_fpriv->dmabufs = RB_ROOT;
+	prime_fpriv->handles = RB_ROOT;
+}
+
+void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
+{
+	/* by now drm_gem_release should've made sure the list is empty */
+	WARN_ON(!RB_EMPTY_ROOT(&prime_fpriv->dmabufs));
+}
+
+/**
+ * drm_gem_dmabuf_export - &dma_buf export implementation for GEM
+ * @dev: parent device for the exported dmabuf
+ * @exp_info: the export information used by dma_buf_export()
+ *
+ * This wraps dma_buf_export() for use by generic GEM drivers that are using
+ * drm_gem_dmabuf_release(). In addition to calling dma_buf_export(), we take
+ * a reference to the &drm_device and the exported &drm_gem_object (stored in
+ * &dma_buf_export_info.priv) which is released by drm_gem_dmabuf_release().
+ *
+ * Returns the new dmabuf.
+ */
+struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
+				      struct dma_buf_export_info *exp_info)
+{
+	struct drm_gem_object *obj = exp_info->priv;
+	struct dma_buf *dma_buf;
+
+	dma_buf = dma_buf_export(exp_info);
+	if (IS_ERR(dma_buf))
+		return dma_buf;
+
+	drm_dev_get(dev);
+	drm_gem_object_get(obj);
+	dma_buf->file->f_mapping = obj->dev->anon_inode->i_mapping;
+
+	return dma_buf;
+}
+EXPORT_SYMBOL(drm_gem_dmabuf_export);
+
+/**
+ * drm_gem_dmabuf_release - &dma_buf release implementation for GEM
+ * @dma_buf: buffer to be released
+ *
+ * Generic release function for dma_bufs exported as PRIME buffers. GEM drivers
+ * must use this in their &dma_buf_ops structure as the release callback.
+ * drm_gem_dmabuf_release() should be used in conjunction with
+ * drm_gem_dmabuf_export().
+ */
+void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+	struct drm_device *dev = obj->dev;
+
+	/* drop the reference on the export fd holds */
+	drm_gem_object_put(obj);
+
+	drm_dev_put(dev);
+}
+EXPORT_SYMBOL(drm_gem_dmabuf_release);
+
+/**
+ * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers
+ * @dev: dev to export the buffer from
+ * @file_priv: drm file-private structure
+ * @prime_fd: fd id of the dma-buf which should be imported
+ * @handle: pointer to storage for the handle of the imported buffer object
+ *
+ * This is the PRIME import function which must be used mandatorily by GEM
+ * drivers to ensure correct lifetime management of the underlying GEM object.
+ * The actual importing of GEM object from the dma-buf is done through the
+ * &drm_driver.gem_prime_import driver callback.
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+int drm_gem_prime_fd_to_handle(struct drm_device *dev,
+			       struct drm_file *file_priv, int prime_fd,
+			       uint32_t *handle)
+{
+	struct dma_buf *dma_buf;
+	struct drm_gem_object *obj;
+	int ret;
+
+	dma_buf = dma_buf_get(prime_fd);
+	if (IS_ERR(dma_buf))
+		return PTR_ERR(dma_buf);
+
+	mutex_lock(&file_priv->prime.lock);
+
+	ret = drm_prime_lookup_buf_handle(&file_priv->prime,
+			dma_buf, handle);
+	if (ret == 0)
+		goto out_put;
+
+	/* never seen this one, need to import */
+	mutex_lock(&dev->object_name_lock);
+	if (dev->driver->gem_prime_import)
+		obj = dev->driver->gem_prime_import(dev, dma_buf);
+	else
+		obj = drm_gem_prime_import(dev, dma_buf);
+	if (IS_ERR(obj)) {
+		ret = PTR_ERR(obj);
+		goto out_unlock;
+	}
+
+	if (obj->dma_buf) {
+		WARN_ON(obj->dma_buf != dma_buf);
+	} else {
+		obj->dma_buf = dma_buf;
+		get_dma_buf(dma_buf);
+	}
+
+	/* _handle_create_tail unconditionally unlocks dev->object_name_lock. */
+	ret = drm_gem_handle_create_tail(file_priv, obj, handle);
+	drm_gem_object_put(obj);
+	if (ret)
+		goto out_put;
+
+	ret = drm_prime_add_buf_handle(&file_priv->prime,
+			dma_buf, *handle);
+	mutex_unlock(&file_priv->prime.lock);
+	if (ret)
+		goto fail;
+
+	dma_buf_put(dma_buf);
+
+	return 0;
+
+fail:
+	/* hmm, if driver attached, we are relying on the free-object path
+	 * to detach.. which seems ok..
+	 */
+	drm_gem_handle_delete(file_priv, *handle);
+	dma_buf_put(dma_buf);
+	return ret;
+
+out_unlock:
+	mutex_unlock(&dev->object_name_lock);
+out_put:
+	mutex_unlock(&file_priv->prime.lock);
+	dma_buf_put(dma_buf);
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);
+
+int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
+				 struct drm_file *file_priv)
+{
+	struct drm_prime_handle *args = data;
+
+	if (!dev->driver->prime_fd_to_handle)
+		return -ENOSYS;
+
+	return dev->driver->prime_fd_to_handle(dev, file_priv,
+			args->fd, &args->handle);
+}
+
+static struct dma_buf *export_and_register_object(struct drm_device *dev,
+						  struct drm_gem_object *obj,
+						  uint32_t flags)
+{
+	struct dma_buf *dmabuf;
+
+	/* prevent races with concurrent gem_close. */
+	if (obj->handle_count == 0) {
+		dmabuf = ERR_PTR(-ENOENT);
+		return dmabuf;
+	}
+
+	if (obj->funcs && obj->funcs->export)
+		dmabuf = obj->funcs->export(obj, flags);
+	else
+		dmabuf = drm_gem_prime_export(obj, flags);
+	if (IS_ERR(dmabuf)) {
+		/* normally the created dma-buf takes ownership of the ref,
+		 * but if that fails then drop the ref
+		 */
+		return dmabuf;
+	}
+
+	/*
+	 * Note that callers do not need to clean up the export cache
+	 * since the check for obj->handle_count guarantees that someone
+	 * will clean it up.
+	 */
+	obj->dma_buf = dmabuf;
+	get_dma_buf(obj->dma_buf);
+
+	return dmabuf;
+}
+
+/**
+ * drm_gem_prime_handle_to_fd - PRIME export function for GEM drivers
+ * @dev: dev to export the buffer from
+ * @file_priv: drm file-private structure
+ * @handle: buffer handle to export
+ * @flags: flags like DRM_CLOEXEC
+ * @prime_fd: pointer to storage for the fd id of the create dma-buf
+ *
+ * This is the PRIME export function which must be used mandatorily by GEM
+ * drivers to ensure correct lifetime management of the underlying GEM object.
+ * The actual exporting from GEM object to a dma-buf is done through the
+ * &drm_gem_object_funcs.export callback.
+ */
+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)
+{
+	struct drm_gem_object *obj;
+	int ret = 0;
+	struct dma_buf *dmabuf;
+
+	mutex_lock(&file_priv->prime.lock);
+	obj = drm_gem_object_lookup(file_priv, handle);
+	if (!obj)  {
+		ret = -ENOENT;
+		goto out_unlock;
+	}
+
+	dmabuf = drm_prime_lookup_buf_by_handle(&file_priv->prime, handle);
+	if (dmabuf) {
+		get_dma_buf(dmabuf);
+		goto out_have_handle;
+	}
+
+	mutex_lock(&dev->object_name_lock);
+	/* re-export the original imported object */
+	if (obj->import_attach) {
+		dmabuf = obj->import_attach->dmabuf;
+		get_dma_buf(dmabuf);
+		goto out_have_obj;
+	}
+
+	if (obj->dma_buf) {
+		get_dma_buf(obj->dma_buf);
+		dmabuf = obj->dma_buf;
+		goto out_have_obj;
+	}
+
+	dmabuf = export_and_register_object(dev, obj, flags);
+	if (IS_ERR(dmabuf)) {
+		/* normally the created dma-buf takes ownership of the ref,
+		 * but if that fails then drop the ref
+		 */
+		ret = PTR_ERR(dmabuf);
+		mutex_unlock(&dev->object_name_lock);
+		goto out;
+	}
+
+out_have_obj:
+	/*
+	 * If we've exported this buffer then cheat and add it to the import list
+	 * so we get the correct handle back. We must do this under the
+	 * protection of dev->object_name_lock to ensure that a racing gem close
+	 * ioctl doesn't miss to remove this buffer handle from the cache.
+	 */
+	ret = drm_prime_add_buf_handle(&file_priv->prime,
+				       dmabuf, handle);
+	mutex_unlock(&dev->object_name_lock);
+	if (ret)
+		goto fail_put_dmabuf;
+
+out_have_handle:
+	ret = dma_buf_fd(dmabuf, flags);
+	/*
+	 * We must _not_ remove the buffer from the handle cache since the newly
+	 * created dma buf is already linked in the global obj->dma_buf pointer,
+	 * and that is invariant as long as a userspace gem handle exists.
+	 * Closing the handle will clean out the cache anyway, so we don't leak.
+	 */
+	if (ret < 0) {
+		goto fail_put_dmabuf;
+	} else {
+		*prime_fd = ret;
+		ret = 0;
+	}
+
+	goto out;
+
+fail_put_dmabuf:
+	dma_buf_put(dmabuf);
+out:
+	drm_gem_object_put(obj);
+out_unlock:
+	mutex_unlock(&file_priv->prime.lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
+
+int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
+				 struct drm_file *file_priv)
+{
+	struct drm_prime_handle *args = data;
+
+	if (!dev->driver->prime_handle_to_fd)
+		return -ENOSYS;
+
+	/* check flags are valid */
+	if (args->flags & ~(DRM_CLOEXEC | DRM_RDWR))
+		return -EINVAL;
+
+	return dev->driver->prime_handle_to_fd(dev, file_priv,
+			args->handle, args->flags, &args->fd);
+}
+
+/**
+ * DOC: PRIME Helpers
+ *
+ * Drivers can implement &drm_gem_object_funcs.export and
+ * &drm_driver.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 some lower-level helpers, which are
+ * again exported for drivers to use individually:
+ *
+ * Exporting buffers
+ * ~~~~~~~~~~~~~~~~~
+ *
+ * Optional pinning of buffers is handled at dma-buf attach and detach time in
+ * drm_gem_map_attach() and drm_gem_map_detach(). Backing storage itself is
+ * handled by drm_gem_map_dma_buf() and drm_gem_unmap_dma_buf(), which relies on
+ * &drm_gem_object_funcs.get_sg_table.
+ *
+ * For kernel-internal access there's drm_gem_dmabuf_vmap() and
+ * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by
+ * drm_gem_dmabuf_mmap().
+ *
+ * Note that these export helpers can only be used if the underlying backing
+ * storage is fully coherent and either permanently pinned, or it is safe to pin
+ * it indefinitely.
+ *
+ * FIXME: The underlying helper functions are named rather inconsistently.
+ *
+ * Importing buffers
+ * ~~~~~~~~~~~~~~~~~
+ *
+ * Importing dma-bufs using drm_gem_prime_import() relies on
+ * &drm_driver.gem_prime_import_sg_table.
+ *
+ * Note that similarly to the export helpers this permanently pins the
+ * underlying backing storage. Which is ok for scanout, but is not the best
+ * option for sharing lots of buffers for rendering.
+ */
+
+/**
+ * drm_gem_map_attach - dma_buf attach implementation for GEM
+ * @dma_buf: buffer to attach device to
+ * @attach: buffer attachment data
+ *
+ * Calls &drm_gem_object_funcs.pin for device specific handling. This can be
+ * used as the &dma_buf_ops.attach callback. Must be used together with
+ * drm_gem_map_detach().
+ *
+ * Returns 0 on success, negative error code on failure.
+ */
+int drm_gem_map_attach(struct dma_buf *dma_buf,
+		       struct dma_buf_attachment *attach)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+
+	return drm_gem_pin(obj);
+}
+EXPORT_SYMBOL(drm_gem_map_attach);
+
+/**
+ * drm_gem_map_detach - dma_buf detach implementation for GEM
+ * @dma_buf: buffer to detach from
+ * @attach: attachment to be detached
+ *
+ * Calls &drm_gem_object_funcs.pin for device specific handling.  Cleans up
+ * &dma_buf_attachment from drm_gem_map_attach(). This can be used as the
+ * &dma_buf_ops.detach callback.
+ */
+void drm_gem_map_detach(struct dma_buf *dma_buf,
+			struct dma_buf_attachment *attach)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+
+	drm_gem_unpin(obj);
+}
+EXPORT_SYMBOL(drm_gem_map_detach);
+
+/**
+ * drm_gem_map_dma_buf - map_dma_buf implementation for GEM
+ * @attach: attachment whose scatterlist is to be returned
+ * @dir: direction of DMA transfer
+ *
+ * Calls &drm_gem_object_funcs.get_sg_table and then maps the scatterlist. This
+ * can be used as the &dma_buf_ops.map_dma_buf callback. Should be used together
+ * with drm_gem_unmap_dma_buf().
+ *
+ * Returns:sg_table containing the scatterlist to be returned; returns ERR_PTR
+ * on error. May return -EINTR if it is interrupted by a signal.
+ */
+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;
+	int ret;
+
+	if (WARN_ON(dir == DMA_NONE))
+		return ERR_PTR(-EINVAL);
+
+	if (WARN_ON(!obj->funcs->get_sg_table))
+		return ERR_PTR(-ENOSYS);
+
+	sgt = obj->funcs->get_sg_table(obj);
+	if (IS_ERR(sgt))
+		return sgt;
+
+	ret = dma_map_sgtable(attach->dev, sgt, dir,
+			      DMA_ATTR_SKIP_CPU_SYNC);
+	if (ret) {
+		sg_free_table(sgt);
+		kfree(sgt);
+		sgt = ERR_PTR(ret);
+	}
+
+	return sgt;
+}
+EXPORT_SYMBOL(drm_gem_map_dma_buf);
+
+/**
+ * drm_gem_unmap_dma_buf - unmap_dma_buf implementation for GEM
+ * @attach: attachment to unmap buffer from
+ * @sgt: scatterlist info of the buffer to unmap
+ * @dir: direction of DMA transfer
+ *
+ * This can be used as the &dma_buf_ops.unmap_dma_buf callback.
+ */
+void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
+			   struct sg_table *sgt,
+			   enum dma_data_direction dir)
+{
+	if (!sgt)
+		return;
+
+	dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
+	sg_free_table(sgt);
+	kfree(sgt);
+}
+EXPORT_SYMBOL(drm_gem_unmap_dma_buf);
+
+/**
+ * drm_gem_dmabuf_vmap - dma_buf vmap implementation for GEM
+ * @dma_buf: buffer to be mapped
+ * @map: the virtual address of the buffer
+ *
+ * Sets up a kernel virtual mapping. This can be used as the &dma_buf_ops.vmap
+ * callback. Calls into &drm_gem_object_funcs.vmap for device specific handling.
+ * The kernel virtual address is returned in map.
+ *
+ * Returns 0 on success or a negative errno code otherwise.
+ */
+int drm_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct iosys_map *map)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+
+	return drm_gem_vmap(obj, map);
+}
+EXPORT_SYMBOL(drm_gem_dmabuf_vmap);
+
+/**
+ * drm_gem_dmabuf_vunmap - dma_buf vunmap implementation for GEM
+ * @dma_buf: buffer to be unmapped
+ * @map: the virtual address of the buffer
+ *
+ * Releases a kernel virtual mapping. This can be used as the
+ * &dma_buf_ops.vunmap callback. Calls into &drm_gem_object_funcs.vunmap for device specific handling.
+ */
+void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct iosys_map *map)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+
+	drm_gem_vunmap(obj, map);
+}
+EXPORT_SYMBOL(drm_gem_dmabuf_vunmap);
+
+/**
+ * drm_gem_prime_mmap - PRIME mmap function for GEM drivers
+ * @obj: GEM object
+ * @vma: Virtual address range
+ *
+ * This function sets up a userspace mapping for PRIME exported buffers using
+ * the same codepath that is used for regular GEM buffer mapping on the DRM fd.
+ * The fake GEM offset is added to vma->vm_pgoff and &drm_driver->fops->mmap is
+ * called to set up the mapping.
+ *
+ * Drivers can use this as their &drm_driver.gem_prime_mmap callback.
+ */
+int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
+{
+	struct drm_file *priv;
+	struct file *fil;
+	int ret;
+
+	/* Add the fake offset */
+	vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
+
+	if (obj->funcs && obj->funcs->mmap) {
+		vma->vm_ops = obj->funcs->vm_ops;
+
+		drm_gem_object_get(obj);
+		ret = obj->funcs->mmap(obj, vma);
+		if (ret) {
+			drm_gem_object_put(obj);
+			return ret;
+		}
+		vma->vm_private_data = obj;
+		return 0;
+	}
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	fil = kzalloc(sizeof(*fil), GFP_KERNEL);
+	if (!priv || !fil) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	/* Used by drm_gem_mmap() to lookup the GEM object */
+	priv->minor = obj->dev->primary;
+	fil->private_data = priv;
+
+	ret = drm_vma_node_allow(&obj->vma_node, priv);
+	if (ret)
+		goto out;
+
+	ret = obj->dev->driver->fops->mmap(fil, vma);
+
+	drm_vma_node_revoke(&obj->vma_node, priv);
+out:
+	kfree(priv);
+	kfree(fil);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_prime_mmap);
+
+/**
+ * drm_gem_dmabuf_mmap - dma_buf mmap implementation for GEM
+ * @dma_buf: buffer to be mapped
+ * @vma: virtual address range
+ *
+ * Provides memory mapping for the buffer. This can be used as the
+ * &dma_buf_ops.mmap callback. It just forwards to &drm_driver.gem_prime_mmap,
+ * which should be set to drm_gem_prime_mmap().
+ *
+ * FIXME: There's really no point to this wrapper, drivers which need anything
+ * else but drm_gem_prime_mmap can roll their own &dma_buf_ops.mmap callback.
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+	struct drm_device *dev = obj->dev;
+
+	if (!dev->driver->gem_prime_mmap)
+		return -ENOSYS;
+
+	return dev->driver->gem_prime_mmap(obj, vma);
+}
+EXPORT_SYMBOL(drm_gem_dmabuf_mmap);
+
+static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
+	.cache_sgt_mapping = true,
+	.attach = drm_gem_map_attach,
+	.detach = drm_gem_map_detach,
+	.map_dma_buf = drm_gem_map_dma_buf,
+	.unmap_dma_buf = drm_gem_unmap_dma_buf,
+	.release = drm_gem_dmabuf_release,
+	.mmap = drm_gem_dmabuf_mmap,
+	.vmap = drm_gem_dmabuf_vmap,
+	.vunmap = drm_gem_dmabuf_vunmap,
+};
+
+/**
+ * drm_prime_pages_to_sg - converts a page array into an sg list
+ * @dev: DRM device
+ * @pages: pointer to the array of page pointers to convert
+ * @nr_pages: length of the page vector
+ *
+ * This helper creates an sg table object from a set of pages
+ * the driver is responsible for mapping the pages into the
+ * importers address space for use with dma_buf itself.
+ *
+ * This is useful for implementing &drm_gem_object_funcs.get_sg_table.
+ */
+struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev,
+				       struct page **pages, unsigned int nr_pages)
+{
+	struct sg_table *sg;
+	size_t max_segment = 0;
+	int err;
+
+	sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
+	if (!sg)
+		return ERR_PTR(-ENOMEM);
+
+	if (dev)
+		max_segment = dma_max_mapping_size(dev->dev);
+	if (max_segment == 0)
+		max_segment = UINT_MAX;
+	err = sg_alloc_table_from_pages_segment(sg, pages, nr_pages, 0,
+						nr_pages << PAGE_SHIFT,
+						max_segment, GFP_KERNEL);
+	if (err) {
+		kfree(sg);
+		sg = ERR_PTR(err);
+	}
+	return sg;
+}
+EXPORT_SYMBOL(drm_prime_pages_to_sg);
+
+/**
+ * drm_prime_get_contiguous_size - returns the contiguous size of the buffer
+ * @sgt: sg_table describing the buffer to check
+ *
+ * This helper calculates the contiguous size in the DMA address space
+ * of the buffer described by the provided sg_table.
+ *
+ * This is useful for implementing
+ * &drm_gem_object_funcs.gem_prime_import_sg_table.
+ */
+unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt)
+{
+	dma_addr_t expected = sg_dma_address(sgt->sgl);
+	struct scatterlist *sg;
+	unsigned long size = 0;
+	int i;
+
+	for_each_sgtable_dma_sg(sgt, sg, i) {
+		unsigned int len = sg_dma_len(sg);
+
+		if (!len)
+			break;
+		if (sg_dma_address(sg) != expected)
+			break;
+		expected += len;
+		size += len;
+	}
+	return size;
+}
+EXPORT_SYMBOL(drm_prime_get_contiguous_size);
+
+/**
+ * drm_gem_prime_export - helper library implementation of the export callback
+ * @obj: GEM object to export
+ * @flags: flags like DRM_CLOEXEC and DRM_RDWR
+ *
+ * This is the implementation of the &drm_gem_object_funcs.export functions for GEM drivers
+ * using the PRIME helpers. It is used as the default in
+ * drm_gem_prime_handle_to_fd().
+ */
+struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
+				     int flags)
+{
+	struct drm_device *dev = obj->dev;
+	struct dma_buf_export_info exp_info = {
+		.exp_name = KBUILD_MODNAME, /* white lie for debug */
+		.owner = dev->driver->fops->owner,
+		.ops = &drm_gem_prime_dmabuf_ops,
+		.size = obj->size,
+		.flags = flags,
+		.priv = obj,
+		.resv = obj->resv,
+	};
+
+	return drm_gem_dmabuf_export(dev, &exp_info);
+}
+EXPORT_SYMBOL(drm_gem_prime_export);
+
+/**
+ * drm_gem_prime_import_dev - core implementation of the import callback
+ * @dev: drm_device to import into
+ * @dma_buf: dma-buf object to import
+ * @attach_dev: struct device to dma_buf attach
+ *
+ * This is the core of drm_gem_prime_import(). It's designed to be called by
+ * drivers who want to use a different device structure than &drm_device.dev for
+ * attaching via dma_buf. This function calls
+ * &drm_driver.gem_prime_import_sg_table internally.
+ *
+ * Drivers must arrange to call drm_prime_gem_destroy() from their
+ * &drm_gem_object_funcs.free hook when using this function.
+ */
+struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
+					    struct dma_buf *dma_buf,
+					    struct device *attach_dev)
+{
+	struct dma_buf_attachment *attach;
+	struct sg_table *sgt;
+	struct drm_gem_object *obj;
+	int ret;
+
+	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_get(obj);
+			return obj;
+		}
+	}
+
+	if (!dev->driver->gem_prime_import_sg_table)
+		return ERR_PTR(-EINVAL);
+
+	attach = dma_buf_attach(dma_buf, attach_dev);
+	if (IS_ERR(attach))
+		return ERR_CAST(attach);
+
+	get_dma_buf(dma_buf);
+
+	sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
+	if (IS_ERR(sgt)) {
+		ret = PTR_ERR(sgt);
+		goto fail_detach;
+	}
+
+	obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
+	if (IS_ERR(obj)) {
+		ret = PTR_ERR(obj);
+		goto fail_unmap;
+	}
+
+	obj->import_attach = attach;
+	obj->resv = dma_buf->resv;
+
+	return obj;
+
+fail_unmap:
+	dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
+fail_detach:
+	dma_buf_detach(dma_buf, attach);
+	dma_buf_put(dma_buf);
+
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(drm_gem_prime_import_dev);
+
+/**
+ * drm_gem_prime_import - helper library implementation of the import callback
+ * @dev: drm_device to import into
+ * @dma_buf: dma-buf object to import
+ *
+ * This is the implementation of the gem_prime_import functions for GEM drivers
+ * using the PRIME helpers. Drivers can use this as their
+ * &drm_driver.gem_prime_import implementation. It is used as the default
+ * implementation in drm_gem_prime_fd_to_handle().
+ *
+ * Drivers must arrange to call drm_prime_gem_destroy() from their
+ * &drm_gem_object_funcs.free hook when using this function.
+ */
+struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
+					    struct dma_buf *dma_buf)
+{
+	return drm_gem_prime_import_dev(dev, dma_buf, dev->dev);
+}
+EXPORT_SYMBOL(drm_gem_prime_import);
+
+/**
+ * drm_prime_sg_to_page_array - convert an sg table into a page array
+ * @sgt: scatter-gather table to convert
+ * @pages: array of page pointers to store the pages in
+ * @max_entries: size of the passed-in array
+ *
+ * Exports an sg table into an array of pages.
+ *
+ * This function is deprecated and strongly discouraged to be used.
+ * The page array is only useful for page faults and those can corrupt fields
+ * in the struct page if they are not handled by the exporting driver.
+ */
+int __deprecated drm_prime_sg_to_page_array(struct sg_table *sgt,
+					    struct page **pages,
+					    int max_entries)
+{
+	struct sg_page_iter page_iter;
+	struct page **p = pages;
+
+	for_each_sgtable_page(sgt, &page_iter, 0) {
+		if (WARN_ON(p - pages >= max_entries))
+			return -1;
+		*p++ = sg_page_iter_page(&page_iter);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(drm_prime_sg_to_page_array);
+
+/**
+ * drm_prime_sg_to_dma_addr_array - convert an sg table into a dma addr array
+ * @sgt: scatter-gather table to convert
+ * @addrs: array to store the dma bus address of each page
+ * @max_entries: size of both the passed-in arrays
+ *
+ * Exports an sg table into an array of addresses.
+ *
+ * Drivers should use this in their &drm_driver.gem_prime_import_sg_table
+ * implementation.
+ */
+int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
+				   int max_entries)
+{
+	struct sg_dma_page_iter dma_iter;
+	dma_addr_t *a = addrs;
+
+	for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
+		if (WARN_ON(a - addrs >= max_entries))
+			return -1;
+		*a++ = sg_page_iter_dma_address(&dma_iter);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(drm_prime_sg_to_dma_addr_array);
+
+/**
+ * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
+ * @obj: GEM object which was created from a dma-buf
+ * @sg: the sg-table which was pinned at import time
+ *
+ * This is the cleanup functions which GEM drivers need to call when they use
+ * drm_gem_prime_import() or drm_gem_prime_import_dev() to import dma-bufs.
+ */
+void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
+{
+	struct dma_buf_attachment *attach;
+	struct dma_buf *dma_buf;
+
+	attach = obj->import_attach;
+	if (sg)
+		dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
+	dma_buf = attach->dmabuf;
+	dma_buf_detach(attach->dmabuf, attach);
+	/* remove the reference */
+	dma_buf_put(dma_buf);
+}
+EXPORT_SYMBOL(drm_prime_gem_destroy);