dma-buf.h
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/*
* 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/scatterlist.h>
#include <linux/list.h>
#include <linux/dma-mapping.h>
#include <linux/fs.h>
struct device;
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.
* @begin_cpu_access: [optional] called before cpu access to invalidate cpu
* caches and allocate backing storage (if not yet done)
* respectively pin the objet into memory.
* @end_cpu_access: [optional] called after cpu access to flush caches.
* @kmap_atomic: maps a page from the buffer into kernel address
* space, users may not block until the subsequent unmap call.
* This callback must not sleep.
* @kunmap_atomic: [optional] unmaps a atomically mapped page from the buffer.
* This Callback must not sleep.
* @kmap: maps a page from the buffer into kernel address space.
* @kunmap: [optional] unmaps a page from the buffer.
* @mmap: used to expose the backing storage to userspace. Note that the
* mapping needs to be coherent - if the exporter doesn't directly
* support this, it needs to fake coherency by shooting down any ptes
* when transitioning away from the cpu domain.
* @vmap: [optional] creates a virtual mapping for the buffer into kernel
* address space. Same restrictions as for vmap and friends apply.
* @vunmap: [optional] unmaps a vmap from the buffer
*/
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 *,
enum dma_data_direction);
/* 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 *);
int (*begin_cpu_access)(struct dma_buf *, size_t, size_t,
enum dma_data_direction);
void (*end_cpu_access)(struct dma_buf *, size_t, size_t,
enum dma_data_direction);
void *(*kmap_atomic)(struct dma_buf *, unsigned long);
void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *);
void *(*kmap)(struct dma_buf *, unsigned long);
void (*kunmap)(struct dma_buf *, unsigned long, void *);
int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
void *(*vmap)(struct dma_buf *);
void (*vunmap)(struct dma_buf *, void *vaddr);
};
/**
* 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.
* @exp_name: name of the exporter; useful for debugging.
* @list_node: node for dma_buf accounting and debugging.
* @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, attach/detach and vmap/unmap */
struct mutex lock;
unsigned vmapping_counter;
void *vmap_ptr;
const char *exp_name;
struct list_head list_node;
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;
};
/**
* get_dma_buf - convenience wrapper for get_file.
* @dmabuf: [in] pointer to dma_buf
*
* Increments the reference count on the dma-buf, needed in case of drivers
* that either need to create additional references to the dmabuf on the
* kernel side. For example, an exporter that needs to keep a dmabuf ptr
* so that subsequent exports don't create a new dmabuf.
*/
static inline void get_dma_buf(struct dma_buf *dmabuf)
{
get_file(dmabuf->file);
}
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_named(void *priv, const struct dma_buf_ops *ops,
size_t size, int flags, const char *);
#define dma_buf_export(priv, ops, size, flags) \
dma_buf_export_named(priv, ops, size, flags, KBUILD_MODNAME)
int dma_buf_fd(struct dma_buf *dmabuf, int flags);
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 *,
enum dma_data_direction);
int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
enum dma_data_direction dir);
void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
enum dma_data_direction dir);
void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
void *dma_buf_kmap(struct dma_buf *, unsigned long);
void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
unsigned long);
void *dma_buf_vmap(struct dma_buf *);
void dma_buf_vunmap(struct dma_buf *, void *vaddr);
int dma_buf_debugfs_create_file(const char *name,
int (*write)(struct seq_file *));
#endif /* __DMA_BUF_H__ */