198 lines
7.5 KiB
C
198 lines
7.5 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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* @exp_name: name of the exporter; useful for debugging.
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* @list_node: node for dma_buf accounting and debugging.
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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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const char *exp_name;
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struct list_head list_node;
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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_named(void *priv, const struct dma_buf_ops *ops,
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size_t size, int flags, const char *);
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#define dma_buf_export(priv, ops, size, flags) \
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dma_buf_export_named(priv, ops, size, flags, __FILE__)
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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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