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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __DMA_BUF_IO_H__
#define __DMA_BUF_IO_H__
#include <linux/dma-buf.h>
struct dma_buf_io_ctx;
struct dma_buf_io_map;
struct dma_buf_io_ops {
/*
* Create a new map for the given ctx. Called with the reservation
* lock held.
*/
struct dma_buf_io_map *(*map)(struct dma_buf_io_ctx *ctx);
/*
* Clean up device specific parts of the @map. Called with the
* reservation lock held.
*/
void (*unmap)(struct dma_buf_io_ctx *ctx, struct dma_buf_io_map *map);
/*
* The user tries to destroy the ctx. Release all device specific
* parts of the token.
*/
void (*release)(struct dma_buf_io_ctx *);
};
struct dma_buf_io_map {
/*
* Counts attached requests and other users. Device specific unmapping
* is deferred until all refs are dropped.
*/
struct percpu_ref refs;
/*
* Shift for the minimum segment size of the mapping.
*/
unsigned min_seg_shift;
struct dma_buf_io_ctx *ctx;
struct completion drained;
};
struct dma_buf_io_ctx {
struct dma_buf_io_map __rcu *map;
struct dma_buf *dmabuf;
enum dma_data_direction dir;
bool is_dead;
void *dev_priv;
const struct dma_buf_io_ops *dev_ops;
};
int dma_buf_io_ctx_create(struct file *file,
struct dma_buf *dmabuf,
enum dma_data_direction dir,
struct dma_buf_io_ctx **ctx);
void dma_buf_io_ctx_release(struct dma_buf_io_ctx *ctx);
struct dma_buf_io_map *dma_buf_io_create_map(struct dma_buf_io_ctx *ctx);
/* Internal helper, see dma_buf_io_get_map() */
static inline struct dma_buf_io_map *
__dma_buf_io_get_map(struct dma_buf_io_ctx *ctx)
{
struct dma_buf_io_map *map;
guard(rcu)();
map = rcu_dereference(ctx->map);
if (unlikely(!map || !percpu_ref_tryget_live_rcu(&map->refs)))
return NULL;
return map;
}
/**
* dma_buf_io_get_map - Create a new or reference an existing map.
* @ctx: [in] dma-buf I/O context
* @nowait: [in] specifies whether it's allowed to block
*
* Create a new or acquire an existing map. On success, it returns
* a referenced map, which should eventually be put down with
* dma_buf_io_map_drop(). If @nowait is set and the function would block,
* it returns -EAGAIN, and the caller is expected to retry from a context
* where blocking is allowed.
*
* Returns a map on success, or ERR_PTR encoded errno otherwise.
*/
static inline struct dma_buf_io_map *
dma_buf_io_get_map(struct dma_buf_io_ctx *ctx, bool nowait)
{
struct dma_buf_io_map *map;
map = __dma_buf_io_get_map(ctx);
if (likely(map))
return map;
if (nowait)
return ERR_PTR(-EAGAIN);
return dma_buf_io_create_map(ctx);
}
/**
* dma_buf_io_map_drop - Drop the map.
* @map: [in] dma-buf I/O map
*
* Put down a reference to the @map acquired via dma_buf_io_get_map().
* Should be called as soon as I/O is completed.
*/
static inline void dma_buf_io_map_drop(struct dma_buf_io_map *map)
{
percpu_ref_put(&map->refs);
}
/*
* Device API
*/
void dma_buf_io_invalidate_mappings(struct dma_buf_io_ctx *ctx);
int dma_buf_io_init_map(struct dma_buf_io_ctx *ctx, struct dma_buf_io_map *map,
struct sg_table *sgt);
void dma_buf_io_detach(struct dma_buf_io_ctx *ctx);
#endif
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