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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, __FILE__) |
|
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); |
#endif /* __DMA_BUF_H__ */ |