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f00b4dad9d
All drivers which implement this need to have some sort of refcount to allow concurrent vmap usage. Hence implement this in the dma-buf core. To protect against concurrent calls we need a lock, which potentially causes new funny locking inversions. But this shouldn't be a problem for exporters with statically allocated backing storage, and more dynamic drivers have decent issues already anyway. Inspired by some refactoring patches from Aaron Plattner, who implemented the same idea, but only for drm/prime drivers. v2: Check in dma_buf_release that no dangling vmaps are left. Suggested by Aaron Plattner. We might want to do similar checks for attachments, but that's for another patch. Also fix up ERR_PTR return for vmap. v3: Check whether the passed-in vmap address matches with the cached one for vunmap. Eventually we might want to remove that parameter - compared to the kmap functions there's no need for the vaddr for unmapping. Suggested by Chris Wilson. v4: Fix a brown-paper-bag bug spotted by Aaron Plattner. Cc: Aaron Plattner <aplattner@nvidia.com> Reviewed-by: Aaron Plattner <aplattner@nvidia.com> Tested-by: Aaron Plattner <aplattner@nvidia.com> Reviewed-by: Rob Clark <rob@ti.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
190 lines
7.3 KiB
C
190 lines
7.3 KiB
C
/*
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* Header file for dma buffer sharing framework.
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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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*
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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
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __DMA_BUF_H__
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#define __DMA_BUF_H__
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#include <linux/file.h>
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#include <linux/err.h>
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#include <linux/scatterlist.h>
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#include <linux/list.h>
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#include <linux/dma-mapping.h>
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#include <linux/fs.h>
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struct device;
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struct dma_buf;
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struct dma_buf_attachment;
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/**
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* struct dma_buf_ops - operations possible on struct dma_buf
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* @attach: [optional] allows different devices to 'attach' themselves to the
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* given buffer. It might return -EBUSY to signal that backing storage
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* is already allocated and incompatible with the requirements
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* of requesting device.
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* @detach: [optional] detach a given device from this buffer.
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* @map_dma_buf: returns list of scatter pages allocated, increases usecount
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* of the buffer. Requires atleast one attach to be called
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* before. Returned sg list should already be mapped into
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* _device_ address space. This call may sleep. May also return
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* -EINTR. Should return -EINVAL if attach hasn't been called yet.
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* @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter
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* pages.
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* @release: release this buffer; to be called after the last dma_buf_put.
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* @begin_cpu_access: [optional] called before cpu access to invalidate cpu
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* caches and allocate backing storage (if not yet done)
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* respectively pin the objet into memory.
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* @end_cpu_access: [optional] called after cpu access to flush caches.
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* @kmap_atomic: maps a page from the buffer into kernel address
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* space, users may not block until the subsequent unmap call.
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* This callback must not sleep.
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* @kunmap_atomic: [optional] unmaps a atomically mapped page from the buffer.
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* This Callback must not sleep.
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* @kmap: maps a page from the buffer into kernel address space.
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* @kunmap: [optional] unmaps a page from the buffer.
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* @mmap: used to expose the backing storage to userspace. Note that the
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* mapping needs to be coherent - if the exporter doesn't directly
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* support this, it needs to fake coherency by shooting down any ptes
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* when transitioning away from the cpu domain.
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* @vmap: [optional] creates a virtual mapping for the buffer into kernel
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* address space. Same restrictions as for vmap and friends apply.
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* @vunmap: [optional] unmaps a vmap from the buffer
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*/
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struct dma_buf_ops {
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int (*attach)(struct dma_buf *, struct device *,
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struct dma_buf_attachment *);
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void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
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/* For {map,unmap}_dma_buf below, any specific buffer attributes
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* required should get added to device_dma_parameters accessible
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* via dev->dma_params.
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*/
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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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void (*unmap_dma_buf)(struct dma_buf_attachment *,
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struct sg_table *,
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enum dma_data_direction);
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/* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
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* if the call would block.
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*/
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/* after final dma_buf_put() */
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void (*release)(struct dma_buf *);
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int (*begin_cpu_access)(struct dma_buf *, size_t, size_t,
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enum dma_data_direction);
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void (*end_cpu_access)(struct dma_buf *, size_t, size_t,
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enum dma_data_direction);
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void *(*kmap_atomic)(struct dma_buf *, unsigned long);
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void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *);
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void *(*kmap)(struct dma_buf *, unsigned long);
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void (*kunmap)(struct dma_buf *, unsigned long, void *);
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int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
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void *(*vmap)(struct dma_buf *);
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void (*vunmap)(struct dma_buf *, void *vaddr);
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};
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/**
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* struct dma_buf - shared buffer object
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* @size: size of the buffer
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* @file: file pointer used for sharing buffers across, and for refcounting.
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* @attachments: list of dma_buf_attachment that denotes all devices attached.
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* @ops: dma_buf_ops associated with this buffer object.
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* @priv: exporter specific private data for this buffer object.
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*/
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struct dma_buf {
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size_t size;
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struct file *file;
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struct list_head attachments;
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const struct dma_buf_ops *ops;
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/* mutex to serialize list manipulation, attach/detach and vmap/unmap */
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struct mutex lock;
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unsigned vmapping_counter;
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void *vmap_ptr;
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void *priv;
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};
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/**
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* struct dma_buf_attachment - holds device-buffer attachment data
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* @dmabuf: buffer for this attachment.
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* @dev: device attached to the buffer.
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* @node: list of dma_buf_attachment.
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* @priv: exporter specific attachment data.
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*
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* This structure holds the attachment information between the dma_buf buffer
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* and its user device(s). The list contains one attachment struct per device
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* attached to the buffer.
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*/
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struct dma_buf_attachment {
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struct dma_buf *dmabuf;
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struct device *dev;
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struct list_head node;
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void *priv;
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};
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/**
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* get_dma_buf - convenience wrapper for get_file.
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* @dmabuf: [in] pointer to dma_buf
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*
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* Increments the reference count on the dma-buf, needed in case of drivers
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* that either need to create additional references to the dmabuf on the
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* kernel side. For example, an exporter that needs to keep a dmabuf ptr
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* so that subsequent exports don't create a new dmabuf.
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*/
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static inline void get_dma_buf(struct dma_buf *dmabuf)
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{
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get_file(dmabuf->file);
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}
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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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void dma_buf_detach(struct dma_buf *dmabuf,
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struct dma_buf_attachment *dmabuf_attach);
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struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
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size_t size, int flags);
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int dma_buf_fd(struct dma_buf *dmabuf, int flags);
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struct dma_buf *dma_buf_get(int fd);
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void dma_buf_put(struct dma_buf *dmabuf);
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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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void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
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enum dma_data_direction);
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int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
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enum dma_data_direction dir);
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void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
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enum dma_data_direction dir);
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void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
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void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
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void *dma_buf_kmap(struct dma_buf *, unsigned long);
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void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
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int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
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unsigned long);
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void *dma_buf_vmap(struct dma_buf *);
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void dma_buf_vunmap(struct dma_buf *, void *vaddr);
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#endif /* __DMA_BUF_H__ */
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