Merge branch 'dma-buf-merge' of git://people.freedesktop.org/~airlied/linux
* 'dma-buf-merge' of git://people.freedesktop.org/~airlied/linux: dma-buf: mark EXPERIMENTAL for 1st release. dma-buf: Documentation for buffer sharing framework dma-buf: Introduce dma buffer sharing mechanismhifive-unleashed-5.1
Linus Torvalds
commit
8e369672af
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@ -0,0 +1,224 @@
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DMA Buffer Sharing API Guide
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Sumit Semwal
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<sumit dot semwal at linaro dot org>
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<sumit dot semwal at ti dot com>
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This document serves as a guide to device-driver writers on what is the dma-buf
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buffer sharing API, how to use it for exporting and using shared buffers.
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Any device driver which wishes to be a part of DMA buffer sharing, can do so as
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either the 'exporter' of buffers, or the 'user' of buffers.
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Say a driver A wants to use buffers created by driver B, then we call B as the
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exporter, and A as buffer-user.
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The exporter
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- implements and manages operations[1] for the buffer
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- allows other users to share the buffer by using dma_buf sharing APIs,
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- manages the details of buffer allocation,
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- decides about the actual backing storage where this allocation happens,
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- takes care of any migration of scatterlist - for all (shared) users of this
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buffer,
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The buffer-user
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- is one of (many) sharing users of the buffer.
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- doesn't need to worry about how the buffer is allocated, or where.
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- needs a mechanism to get access to the scatterlist that makes up this buffer
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in memory, mapped into its own address space, so it can access the same area
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of memory.
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*IMPORTANT*: [see https://lkml.org/lkml/2011/12/20/211 for more details]
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For this first version, A buffer shared using the dma_buf sharing API:
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- *may* be exported to user space using "mmap" *ONLY* by exporter, outside of
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this framework.
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- may be used *ONLY* by importers that do not need CPU access to the buffer.
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The dma_buf buffer sharing API usage contains the following steps:
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1. Exporter announces that it wishes to export a buffer
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2. Userspace gets the file descriptor associated with the exported buffer, and
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passes it around to potential buffer-users based on use case
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3. Each buffer-user 'connects' itself to the buffer
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4. When needed, buffer-user requests access to the buffer from exporter
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5. When finished with its use, the buffer-user notifies end-of-DMA to exporter
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6. when buffer-user is done using this buffer completely, it 'disconnects'
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itself from the buffer.
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1. Exporter's announcement of buffer export
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The buffer exporter announces its wish to export a buffer. In this, it
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connects its own private buffer data, provides implementation for operations
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that can be performed on the exported dma_buf, and flags for the file
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associated with this buffer.
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Interface:
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struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
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size_t size, int flags)
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If this succeeds, dma_buf_export allocates a dma_buf structure, and returns a
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pointer to the same. It also associates an anonymous file with this buffer,
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so it can be exported. On failure to allocate the dma_buf object, it returns
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NULL.
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2. Userspace gets a handle to pass around to potential buffer-users
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Userspace entity requests for a file-descriptor (fd) which is a handle to the
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anonymous file associated with the buffer. It can then share the fd with other
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drivers and/or processes.
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Interface:
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int dma_buf_fd(struct dma_buf *dmabuf)
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This API installs an fd for the anonymous file associated with this buffer;
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returns either 'fd', or error.
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3. Each buffer-user 'connects' itself to the buffer
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Each buffer-user now gets a reference to the buffer, using the fd passed to
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it.
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Interface:
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struct dma_buf *dma_buf_get(int fd)
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This API will return a reference to the dma_buf, and increment refcount for
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it.
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After this, the buffer-user needs to attach its device with the buffer, which
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helps the exporter to know of device buffer constraints.
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Interface:
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struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
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struct device *dev)
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This API returns reference to an attachment structure, which is then used
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for scatterlist operations. It will optionally call the 'attach' dma_buf
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operation, if provided by the exporter.
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The dma-buf sharing framework does the bookkeeping bits related to managing
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the list of all attachments to a buffer.
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Until this stage, the buffer-exporter has the option to choose not to actually
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allocate the backing storage for this buffer, but wait for the first buffer-user
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to request use of buffer for allocation.
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4. When needed, buffer-user requests access to the buffer
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Whenever a buffer-user wants to use the buffer for any DMA, it asks for
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access to the buffer using dma_buf_map_attachment API. At least one attach to
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the buffer must have happened before map_dma_buf can be called.
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Interface:
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struct sg_table * dma_buf_map_attachment(struct dma_buf_attachment *,
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enum dma_data_direction);
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This is a wrapper to dma_buf->ops->map_dma_buf operation, which hides the
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"dma_buf->ops->" indirection from the users of this interface.
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In struct dma_buf_ops, map_dma_buf is defined as
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struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
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enum dma_data_direction);
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It is one of the buffer operations that must be implemented by the exporter.
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It should return the sg_table containing scatterlist for this buffer, mapped
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into caller's address space.
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If this is being called for the first time, the exporter can now choose to
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scan through the list of attachments for this buffer, collate the requirements
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of the attached devices, and choose an appropriate backing storage for the
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buffer.
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Based on enum dma_data_direction, it might be possible to have multiple users
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accessing at the same time (for reading, maybe), or any other kind of sharing
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that the exporter might wish to make available to buffer-users.
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map_dma_buf() operation can return -EINTR if it is interrupted by a signal.
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5. When finished, the buffer-user notifies end-of-DMA to exporter
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Once the DMA for the current buffer-user is over, it signals 'end-of-DMA' to
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the exporter using the dma_buf_unmap_attachment API.
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Interface:
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void dma_buf_unmap_attachment(struct dma_buf_attachment *,
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struct sg_table *);
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This is a wrapper to dma_buf->ops->unmap_dma_buf() operation, which hides the
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"dma_buf->ops->" indirection from the users of this interface.
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In struct dma_buf_ops, unmap_dma_buf is defined as
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void (*unmap_dma_buf)(struct dma_buf_attachment *, struct sg_table *);
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unmap_dma_buf signifies the end-of-DMA for the attachment provided. Like
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map_dma_buf, this API also must be implemented by the exporter.
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6. when buffer-user is done using this buffer, it 'disconnects' itself from the
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buffer.
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After the buffer-user has no more interest in using this buffer, it should
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disconnect itself from the buffer:
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- it first detaches itself from the buffer.
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Interface:
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void dma_buf_detach(struct dma_buf *dmabuf,
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struct dma_buf_attachment *dmabuf_attach);
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This API removes the attachment from the list in dmabuf, and optionally calls
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dma_buf->ops->detach(), if provided by exporter, for any housekeeping bits.
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- Then, the buffer-user returns the buffer reference to exporter.
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Interface:
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void dma_buf_put(struct dma_buf *dmabuf);
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This API then reduces the refcount for this buffer.
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If, as a result of this call, the refcount becomes 0, the 'release' file
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operation related to this fd is called. It calls the dmabuf->ops->release()
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operation in turn, and frees the memory allocated for dmabuf when exported.
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NOTES:
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- Importance of attach-detach and {map,unmap}_dma_buf operation pairs
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The attach-detach calls allow the exporter to figure out backing-storage
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constraints for the currently-interested devices. This allows preferential
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allocation, and/or migration of pages across different types of storage
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available, if possible.
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Bracketing of DMA access with {map,unmap}_dma_buf operations is essential
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to allow just-in-time backing of storage, and migration mid-way through a
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use-case.
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- Migration of backing storage if needed
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If after
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- at least one map_dma_buf has happened,
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- and the backing storage has been allocated for this buffer,
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another new buffer-user intends to attach itself to this buffer, it might
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be allowed, if possible for the exporter.
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In case it is allowed by the exporter:
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if the new buffer-user has stricter 'backing-storage constraints', and the
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exporter can handle these constraints, the exporter can just stall on the
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map_dma_buf until all outstanding access is completed (as signalled by
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unmap_dma_buf).
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Once all users have finished accessing and have unmapped this buffer, the
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exporter could potentially move the buffer to the stricter backing-storage,
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and then allow further {map,unmap}_dma_buf operations from any buffer-user
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from the migrated backing-storage.
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If the exporter cannot fulfil the backing-storage constraints of the new
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buffer-user device as requested, dma_buf_attach() would return an error to
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denote non-compatibility of the new buffer-sharing request with the current
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buffer.
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If the exporter chooses not to allow an attach() operation once a
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map_dma_buf() API has been called, it simply returns an error.
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References:
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[1] struct dma_buf_ops in include/linux/dma-buf.h
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[2] All interfaces mentioned above defined in include/linux/dma-buf.h
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@ -174,4 +174,15 @@ config SYS_HYPERVISOR
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source "drivers/base/regmap/Kconfig"
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config DMA_SHARED_BUFFER
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bool "Buffer framework to be shared between drivers"
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default n
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select ANON_INODES
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depends on EXPERIMENTAL
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help
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This option enables the framework for buffer-sharing between
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multiple drivers. A buffer is associated with a file using driver
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APIs extension; the file's descriptor can then be passed on to other
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driver.
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endmenu
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@ -9,6 +9,7 @@ obj-$(CONFIG_DEVTMPFS) += devtmpfs.o
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obj-y += power/
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obj-$(CONFIG_HAS_DMA) += dma-mapping.o
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obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o
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obj-$(CONFIG_DMA_SHARED_BUFFER) += dma-buf.o
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obj-$(CONFIG_ISA) += isa.o
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obj-$(CONFIG_FW_LOADER) += firmware_class.o
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obj-$(CONFIG_NUMA) += node.o
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|
|
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@ -0,0 +1,291 @@
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/*
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* Framework for buffer objects that can be shared across devices/subsystems.
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*
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* Copyright(C) 2011 Linaro Limited. All rights reserved.
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* Author: Sumit Semwal <sumit.semwal@ti.com>
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*
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* Many thanks to linaro-mm-sig list, and specially
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* Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
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* Daniel Vetter <daniel@ffwll.ch> for their support in creation and
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* refining of this idea.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
|
||||
* This program is distributed in the hope that it will be useful, but WITHOUT
|
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
||||
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
|
||||
* more details.
|
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*
|
||||
* You should have received a copy of the GNU General Public License along with
|
||||
* this program. If not, see <http://www.gnu.org/licenses/>.
|
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*/
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#include <linux/fs.h>
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#include <linux/slab.h>
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#include <linux/dma-buf.h>
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#include <linux/anon_inodes.h>
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#include <linux/export.h>
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static inline int is_dma_buf_file(struct file *);
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static int dma_buf_release(struct inode *inode, struct file *file)
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{
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struct dma_buf *dmabuf;
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if (!is_dma_buf_file(file))
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return -EINVAL;
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dmabuf = file->private_data;
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dmabuf->ops->release(dmabuf);
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kfree(dmabuf);
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return 0;
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}
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static const struct file_operations dma_buf_fops = {
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.release = dma_buf_release,
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};
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|
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/*
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* is_dma_buf_file - Check if struct file* is associated with dma_buf
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*/
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static inline int is_dma_buf_file(struct file *file)
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{
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||||
return file->f_op == &dma_buf_fops;
|
||||
}
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|
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/**
|
||||
* dma_buf_export - Creates a new dma_buf, and associates an anon file
|
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* with this buffer, so it can be exported.
|
||||
* Also connect the allocator specific data and ops to the buffer.
|
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*
|
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* @priv: [in] Attach private data of allocator to this buffer
|
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* @ops: [in] Attach allocator-defined dma buf ops to the new buffer.
|
||||
* @size: [in] Size of the buffer
|
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* @flags: [in] mode flags for the file.
|
||||
*
|
||||
* Returns, on success, a newly created dma_buf object, which wraps the
|
||||
* supplied private data and operations for dma_buf_ops. On either missing
|
||||
* ops, or error in allocating struct dma_buf, will return negative error.
|
||||
*
|
||||
*/
|
||||
struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
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||||
size_t size, int flags)
|
||||
{
|
||||
struct dma_buf *dmabuf;
|
||||
struct file *file;
|
||||
|
||||
if (WARN_ON(!priv || !ops
|
||||
|| !ops->map_dma_buf
|
||||
|| !ops->unmap_dma_buf
|
||||
|| !ops->release)) {
|
||||
return ERR_PTR(-EINVAL);
|
||||
}
|
||||
|
||||
dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
|
||||
if (dmabuf == NULL)
|
||||
return ERR_PTR(-ENOMEM);
|
||||
|
||||
dmabuf->priv = priv;
|
||||
dmabuf->ops = ops;
|
||||
dmabuf->size = size;
|
||||
|
||||
file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
|
||||
|
||||
dmabuf->file = file;
|
||||
|
||||
mutex_init(&dmabuf->lock);
|
||||
INIT_LIST_HEAD(&dmabuf->attachments);
|
||||
|
||||
return dmabuf;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_export);
|
||||
|
||||
|
||||
/**
|
||||
* dma_buf_fd - returns a file descriptor for the given dma_buf
|
||||
* @dmabuf: [in] pointer to dma_buf for which fd is required.
|
||||
*
|
||||
* On success, returns an associated 'fd'. Else, returns error.
|
||||
*/
|
||||
int dma_buf_fd(struct dma_buf *dmabuf)
|
||||
{
|
||||
int error, fd;
|
||||
|
||||
if (!dmabuf || !dmabuf->file)
|
||||
return -EINVAL;
|
||||
|
||||
error = get_unused_fd();
|
||||
if (error < 0)
|
||||
return error;
|
||||
fd = error;
|
||||
|
||||
fd_install(fd, dmabuf->file);
|
||||
|
||||
return fd;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_fd);
|
||||
|
||||
/**
|
||||
* dma_buf_get - returns the dma_buf structure related to an fd
|
||||
* @fd: [in] fd associated with the dma_buf to be returned
|
||||
*
|
||||
* On success, returns the dma_buf structure associated with an fd; uses
|
||||
* file's refcounting done by fget to increase refcount. returns ERR_PTR
|
||||
* otherwise.
|
||||
*/
|
||||
struct dma_buf *dma_buf_get(int fd)
|
||||
{
|
||||
struct file *file;
|
||||
|
||||
file = fget(fd);
|
||||
|
||||
if (!file)
|
||||
return ERR_PTR(-EBADF);
|
||||
|
||||
if (!is_dma_buf_file(file)) {
|
||||
fput(file);
|
||||
return ERR_PTR(-EINVAL);
|
||||
}
|
||||
|
||||
return file->private_data;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_get);
|
||||
|
||||
/**
|
||||
* dma_buf_put - decreases refcount of the buffer
|
||||
* @dmabuf: [in] buffer to reduce refcount of
|
||||
*
|
||||
* Uses file's refcounting done implicitly by fput()
|
||||
*/
|
||||
void dma_buf_put(struct dma_buf *dmabuf)
|
||||
{
|
||||
if (WARN_ON(!dmabuf || !dmabuf->file))
|
||||
return;
|
||||
|
||||
fput(dmabuf->file);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_put);
|
||||
|
||||
/**
|
||||
* dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
|
||||
* calls attach() of dma_buf_ops to allow device-specific attach functionality
|
||||
* @dmabuf: [in] buffer to attach device to.
|
||||
* @dev: [in] device to be attached.
|
||||
*
|
||||
* Returns struct dma_buf_attachment * for this attachment; may return negative
|
||||
* error codes.
|
||||
*
|
||||
*/
|
||||
struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
|
||||
struct device *dev)
|
||||
{
|
||||
struct dma_buf_attachment *attach;
|
||||
int ret;
|
||||
|
||||
if (WARN_ON(!dmabuf || !dev || !dmabuf->ops))
|
||||
return ERR_PTR(-EINVAL);
|
||||
|
||||
attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
|
||||
if (attach == NULL)
|
||||
goto err_alloc;
|
||||
|
||||
mutex_lock(&dmabuf->lock);
|
||||
|
||||
attach->dev = dev;
|
||||
attach->dmabuf = dmabuf;
|
||||
if (dmabuf->ops->attach) {
|
||||
ret = dmabuf->ops->attach(dmabuf, dev, attach);
|
||||
if (ret)
|
||||
goto err_attach;
|
||||
}
|
||||
list_add(&attach->node, &dmabuf->attachments);
|
||||
|
||||
mutex_unlock(&dmabuf->lock);
|
||||
return attach;
|
||||
|
||||
err_alloc:
|
||||
return ERR_PTR(-ENOMEM);
|
||||
err_attach:
|
||||
kfree(attach);
|
||||
mutex_unlock(&dmabuf->lock);
|
||||
return ERR_PTR(ret);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_attach);
|
||||
|
||||
/**
|
||||
* dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
|
||||
* optionally calls detach() of dma_buf_ops for device-specific detach
|
||||
* @dmabuf: [in] buffer to detach from.
|
||||
* @attach: [in] attachment to be detached; is free'd after this call.
|
||||
*
|
||||
*/
|
||||
void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
|
||||
{
|
||||
if (WARN_ON(!dmabuf || !attach || !dmabuf->ops))
|
||||
return;
|
||||
|
||||
mutex_lock(&dmabuf->lock);
|
||||
list_del(&attach->node);
|
||||
if (dmabuf->ops->detach)
|
||||
dmabuf->ops->detach(dmabuf, attach);
|
||||
|
||||
mutex_unlock(&dmabuf->lock);
|
||||
kfree(attach);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_detach);
|
||||
|
||||
/**
|
||||
* dma_buf_map_attachment - Returns the scatterlist table of the attachment;
|
||||
* mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
|
||||
* dma_buf_ops.
|
||||
* @attach: [in] attachment whose scatterlist is to be returned
|
||||
* @direction: [in] direction of DMA transfer
|
||||
*
|
||||
* Returns sg_table containing the scatterlist to be returned; may return NULL
|
||||
* or ERR_PTR.
|
||||
*
|
||||
*/
|
||||
struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
|
||||
enum dma_data_direction direction)
|
||||
{
|
||||
struct sg_table *sg_table = ERR_PTR(-EINVAL);
|
||||
|
||||
might_sleep();
|
||||
|
||||
if (WARN_ON(!attach || !attach->dmabuf || !attach->dmabuf->ops))
|
||||
return ERR_PTR(-EINVAL);
|
||||
|
||||
mutex_lock(&attach->dmabuf->lock);
|
||||
if (attach->dmabuf->ops->map_dma_buf)
|
||||
sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
|
||||
mutex_unlock(&attach->dmabuf->lock);
|
||||
|
||||
return sg_table;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
|
||||
|
||||
/**
|
||||
* dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
|
||||
* deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
|
||||
* dma_buf_ops.
|
||||
* @attach: [in] attachment to unmap buffer from
|
||||
* @sg_table: [in] scatterlist info of the buffer to unmap
|
||||
*
|
||||
*/
|
||||
void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
|
||||
struct sg_table *sg_table)
|
||||
{
|
||||
if (WARN_ON(!attach || !attach->dmabuf || !sg_table
|
||||
|| !attach->dmabuf->ops))
|
||||
return;
|
||||
|
||||
mutex_lock(&attach->dmabuf->lock);
|
||||
if (attach->dmabuf->ops->unmap_dma_buf)
|
||||
attach->dmabuf->ops->unmap_dma_buf(attach, sg_table);
|
||||
mutex_unlock(&attach->dmabuf->lock);
|
||||
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
|
||||
|
|
@ -0,0 +1,176 @@
|
|||
/*
|
||||
* Header file for dma buffer sharing framework.
|
||||
*
|
||||
* Copyright(C) 2011 Linaro Limited. All rights reserved.
|
||||
* Author: Sumit Semwal <sumit.semwal@ti.com>
|
||||
*
|
||||
* Many thanks to linaro-mm-sig list, and specially
|
||||
* Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
|
||||
* Daniel Vetter <daniel@ffwll.ch> for their support in creation and
|
||||
* refining of this idea.
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or modify it
|
||||
* under the terms of the GNU General Public License version 2 as published by
|
||||
* the Free Software Foundation.
|
||||
*
|
||||
* This program is distributed in the hope that it will be useful, but WITHOUT
|
||||
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
||||
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
|
||||
* more details.
|
||||
*
|
||||
* You should have received a copy of the GNU General Public License along with
|
||||
* this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
*/
|
||||
#ifndef __DMA_BUF_H__
|
||||
#define __DMA_BUF_H__
|
||||
|
||||
#include <linux/file.h>
|
||||
#include <linux/err.h>
|
||||
#include <linux/device.h>
|
||||
#include <linux/scatterlist.h>
|
||||
#include <linux/list.h>
|
||||
#include <linux/dma-mapping.h>
|
||||
|
||||
struct dma_buf;
|
||||
struct dma_buf_attachment;
|
||||
|
||||
/**
|
||||
* struct dma_buf_ops - operations possible on struct dma_buf
|
||||
* @attach: [optional] allows different devices to 'attach' themselves to the
|
||||
* given buffer. It might return -EBUSY to signal that backing storage
|
||||
* is already allocated and incompatible with the requirements
|
||||
* of requesting device.
|
||||
* @detach: [optional] detach a given device from this buffer.
|
||||
* @map_dma_buf: returns list of scatter pages allocated, increases usecount
|
||||
* of the buffer. Requires atleast one attach to be called
|
||||
* before. Returned sg list should already be mapped into
|
||||
* _device_ address space. This call may sleep. May also return
|
||||
* -EINTR. Should return -EINVAL if attach hasn't been called yet.
|
||||
* @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter
|
||||
* pages.
|
||||
* @release: release this buffer; to be called after the last dma_buf_put.
|
||||
*/
|
||||
struct dma_buf_ops {
|
||||
int (*attach)(struct dma_buf *, struct device *,
|
||||
struct dma_buf_attachment *);
|
||||
|
||||
void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
|
||||
|
||||
/* For {map,unmap}_dma_buf below, any specific buffer attributes
|
||||
* required should get added to device_dma_parameters accessible
|
||||
* via dev->dma_params.
|
||||
*/
|
||||
struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
|
||||
enum dma_data_direction);
|
||||
void (*unmap_dma_buf)(struct dma_buf_attachment *,
|
||||
struct sg_table *);
|
||||
/* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
|
||||
* if the call would block.
|
||||
*/
|
||||
|
||||
/* after final dma_buf_put() */
|
||||
void (*release)(struct dma_buf *);
|
||||
|
||||
};
|
||||
|
||||
/**
|
||||
* struct dma_buf - shared buffer object
|
||||
* @size: size of the buffer
|
||||
* @file: file pointer used for sharing buffers across, and for refcounting.
|
||||
* @attachments: list of dma_buf_attachment that denotes all devices attached.
|
||||
* @ops: dma_buf_ops associated with this buffer object.
|
||||
* @priv: exporter specific private data for this buffer object.
|
||||
*/
|
||||
struct dma_buf {
|
||||
size_t size;
|
||||
struct file *file;
|
||||
struct list_head attachments;
|
||||
const struct dma_buf_ops *ops;
|
||||
/* mutex to serialize list manipulation and other ops */
|
||||
struct mutex lock;
|
||||
void *priv;
|
||||
};
|
||||
|
||||
/**
|
||||
* struct dma_buf_attachment - holds device-buffer attachment data
|
||||
* @dmabuf: buffer for this attachment.
|
||||
* @dev: device attached to the buffer.
|
||||
* @node: list of dma_buf_attachment.
|
||||
* @priv: exporter specific attachment data.
|
||||
*
|
||||
* This structure holds the attachment information between the dma_buf buffer
|
||||
* and its user device(s). The list contains one attachment struct per device
|
||||
* attached to the buffer.
|
||||
*/
|
||||
struct dma_buf_attachment {
|
||||
struct dma_buf *dmabuf;
|
||||
struct device *dev;
|
||||
struct list_head node;
|
||||
void *priv;
|
||||
};
|
||||
|
||||
#ifdef CONFIG_DMA_SHARED_BUFFER
|
||||
struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
|
||||
struct device *dev);
|
||||
void dma_buf_detach(struct dma_buf *dmabuf,
|
||||
struct dma_buf_attachment *dmabuf_attach);
|
||||
struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
|
||||
size_t size, int flags);
|
||||
int dma_buf_fd(struct dma_buf *dmabuf);
|
||||
struct dma_buf *dma_buf_get(int fd);
|
||||
void dma_buf_put(struct dma_buf *dmabuf);
|
||||
|
||||
struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
|
||||
enum dma_data_direction);
|
||||
void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *);
|
||||
#else
|
||||
|
||||
static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
|
||||
struct device *dev)
|
||||
{
|
||||
return ERR_PTR(-ENODEV);
|
||||
}
|
||||
|
||||
static inline void dma_buf_detach(struct dma_buf *dmabuf,
|
||||
struct dma_buf_attachment *dmabuf_attach)
|
||||
{
|
||||
return;
|
||||
}
|
||||
|
||||
static inline struct dma_buf *dma_buf_export(void *priv,
|
||||
struct dma_buf_ops *ops,
|
||||
size_t size, int flags)
|
||||
{
|
||||
return ERR_PTR(-ENODEV);
|
||||
}
|
||||
|
||||
static inline int dma_buf_fd(struct dma_buf *dmabuf)
|
||||
{
|
||||
return -ENODEV;
|
||||
}
|
||||
|
||||
static inline struct dma_buf *dma_buf_get(int fd)
|
||||
{
|
||||
return ERR_PTR(-ENODEV);
|
||||
}
|
||||
|
||||
static inline void dma_buf_put(struct dma_buf *dmabuf)
|
||||
{
|
||||
return;
|
||||
}
|
||||
|
||||
static inline struct sg_table *dma_buf_map_attachment(
|
||||
struct dma_buf_attachment *attach, enum dma_data_direction write)
|
||||
{
|
||||
return ERR_PTR(-ENODEV);
|
||||
}
|
||||
|
||||
static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
|
||||
struct sg_table *sg)
|
||||
{
|
||||
return;
|
||||
}
|
||||
|
||||
#endif /* CONFIG_DMA_SHARED_BUFFER */
|
||||
|
||||
#endif /* __DMA_BUF_H__ */
|
||||
Loading…
Reference in New Issue