424 lines
14 KiB
C
424 lines
14 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
/*
|
|
* 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.
|
|
*/
|
|
#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>
|
|
#include <linux/dma-fence.h>
|
|
#include <linux/wait.h>
|
|
|
|
struct device;
|
|
struct dma_buf;
|
|
struct dma_buf_attachment;
|
|
|
|
/**
|
|
* struct dma_buf_ops - operations possible on struct dma_buf
|
|
* @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 {
|
|
/**
|
|
* @cache_sgt_mapping:
|
|
*
|
|
* If true the framework will cache the first mapping made for each
|
|
* attachment. This avoids creating mappings for attachments multiple
|
|
* times.
|
|
*/
|
|
bool cache_sgt_mapping;
|
|
|
|
/**
|
|
* @attach:
|
|
*
|
|
* This is called from dma_buf_attach() to make sure that a given
|
|
* &dma_buf_attachment.dev can access the provided &dma_buf. Exporters
|
|
* which support buffer objects in special locations like VRAM or
|
|
* device-specific carveout areas should check whether the buffer could
|
|
* be move to system memory (or directly accessed by the provided
|
|
* device), and otherwise need to fail the attach operation.
|
|
*
|
|
* The exporter should also in general check whether the current
|
|
* allocation fullfills the DMA constraints of the new device. If this
|
|
* is not the case, and the allocation cannot be moved, it should also
|
|
* fail the attach operation.
|
|
*
|
|
* Any exporter-private housekeeping data can be stored in the
|
|
* &dma_buf_attachment.priv pointer.
|
|
*
|
|
* This callback is optional.
|
|
*
|
|
* Returns:
|
|
*
|
|
* 0 on success, negative error code on failure. It might return -EBUSY
|
|
* to signal that backing storage is already allocated and incompatible
|
|
* with the requirements of requesting device.
|
|
*/
|
|
int (*attach)(struct dma_buf *, struct dma_buf_attachment *);
|
|
|
|
/**
|
|
* @detach:
|
|
*
|
|
* This is called by dma_buf_detach() to release a &dma_buf_attachment.
|
|
* Provided so that exporters can clean up any housekeeping for an
|
|
* &dma_buf_attachment.
|
|
*
|
|
* This callback is optional.
|
|
*/
|
|
void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
|
|
|
|
/**
|
|
* @map_dma_buf:
|
|
*
|
|
* This is called by dma_buf_map_attachment() and is used to map a
|
|
* shared &dma_buf into device address space, and it is mandatory. It
|
|
* can only be called if @attach has been called successfully. This
|
|
* essentially pins the DMA buffer into place, and it cannot be moved
|
|
* any more
|
|
*
|
|
* This call may sleep, e.g. when the backing storage first needs to be
|
|
* allocated, or moved to a location suitable for all currently attached
|
|
* devices.
|
|
*
|
|
* Note that any specific buffer attributes required for this function
|
|
* should get added to device_dma_parameters accessible via
|
|
* &device.dma_params from the &dma_buf_attachment. The @attach callback
|
|
* should also check these constraints.
|
|
*
|
|
* If this is being called for the first time, the exporter can now
|
|
* choose to scan through the list of attachments for this buffer,
|
|
* collate the requirements of the attached devices, and choose an
|
|
* appropriate backing storage for the buffer.
|
|
*
|
|
* Based on enum dma_data_direction, it might be possible to have
|
|
* multiple users accessing at the same time (for reading, maybe), or
|
|
* any other kind of sharing that the exporter might wish to make
|
|
* available to buffer-users.
|
|
*
|
|
* Returns:
|
|
*
|
|
* A &sg_table scatter list of or the backing storage of the DMA buffer,
|
|
* already mapped into the device address space of the &device attached
|
|
* with the provided &dma_buf_attachment.
|
|
*
|
|
* On failure, returns a negative error value wrapped into a pointer.
|
|
* May also return -EINTR when a signal was received while being
|
|
* blocked.
|
|
*/
|
|
struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
|
|
enum dma_data_direction);
|
|
/**
|
|
* @unmap_dma_buf:
|
|
*
|
|
* This is called by dma_buf_unmap_attachment() and should unmap and
|
|
* release the &sg_table allocated in @map_dma_buf, and it is mandatory.
|
|
* It should also unpin the backing storage if this is the last mapping
|
|
* of the DMA buffer, it the exporter supports backing storage
|
|
* migration.
|
|
*/
|
|
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.
|
|
*/
|
|
|
|
/**
|
|
* @release:
|
|
*
|
|
* Called after the last dma_buf_put to release the &dma_buf, and
|
|
* mandatory.
|
|
*/
|
|
void (*release)(struct dma_buf *);
|
|
|
|
/**
|
|
* @begin_cpu_access:
|
|
*
|
|
* This is called from dma_buf_begin_cpu_access() and allows the
|
|
* exporter to ensure that the memory is actually available for cpu
|
|
* access - the exporter might need to allocate or swap-in and pin the
|
|
* backing storage. The exporter also needs to ensure that cpu access is
|
|
* coherent for the access direction. The direction can be used by the
|
|
* exporter to optimize the cache flushing, i.e. access with a different
|
|
* direction (read instead of write) might return stale or even bogus
|
|
* data (e.g. when the exporter needs to copy the data to temporary
|
|
* storage).
|
|
*
|
|
* This callback is optional.
|
|
*
|
|
* FIXME: This is both called through the DMA_BUF_IOCTL_SYNC command
|
|
* from userspace (where storage shouldn't be pinned to avoid handing
|
|
* de-factor mlock rights to userspace) and for the kernel-internal
|
|
* users of the various kmap interfaces, where the backing storage must
|
|
* be pinned to guarantee that the atomic kmap calls can succeed. Since
|
|
* there's no in-kernel users of the kmap interfaces yet this isn't a
|
|
* real problem.
|
|
*
|
|
* Returns:
|
|
*
|
|
* 0 on success or a negative error code on failure. This can for
|
|
* example fail when the backing storage can't be allocated. Can also
|
|
* return -ERESTARTSYS or -EINTR when the call has been interrupted and
|
|
* needs to be restarted.
|
|
*/
|
|
int (*begin_cpu_access)(struct dma_buf *, enum dma_data_direction);
|
|
|
|
/**
|
|
* @end_cpu_access:
|
|
*
|
|
* This is called from dma_buf_end_cpu_access() when the importer is
|
|
* done accessing the CPU. The exporter can use this to flush caches and
|
|
* unpin any resources pinned in @begin_cpu_access.
|
|
* The result of any dma_buf kmap calls after end_cpu_access is
|
|
* undefined.
|
|
*
|
|
* This callback is optional.
|
|
*
|
|
* Returns:
|
|
*
|
|
* 0 on success or a negative error code on failure. Can return
|
|
* -ERESTARTSYS or -EINTR when the call has been interrupted and needs
|
|
* to be restarted.
|
|
*/
|
|
int (*end_cpu_access)(struct dma_buf *, enum dma_data_direction);
|
|
|
|
/**
|
|
* @mmap:
|
|
*
|
|
* This callback is used by the dma_buf_mmap() function
|
|
*
|
|
* Note that the mapping needs to be incoherent, userspace is expected
|
|
* to braket CPU access using the DMA_BUF_IOCTL_SYNC interface.
|
|
*
|
|
* Because dma-buf buffers have invariant size over their lifetime, the
|
|
* dma-buf core checks whether a vma is too large and rejects such
|
|
* mappings. The exporter hence does not need to duplicate this check.
|
|
* Drivers do not need to check this themselves.
|
|
*
|
|
* If an exporter needs to manually flush caches and hence needs to fake
|
|
* coherency for mmap support, it needs to be able to zap all the ptes
|
|
* pointing at the backing storage. Now linux mm needs a struct
|
|
* address_space associated with the struct file stored in vma->vm_file
|
|
* to do that with the function unmap_mapping_range. But the dma_buf
|
|
* framework only backs every dma_buf fd with the anon_file struct file,
|
|
* i.e. all dma_bufs share the same file.
|
|
*
|
|
* Hence exporters need to setup their own file (and address_space)
|
|
* association by setting vma->vm_file and adjusting vma->vm_pgoff in
|
|
* the dma_buf mmap callback. In the specific case of a gem driver the
|
|
* exporter could use the shmem file already provided by gem (and set
|
|
* vm_pgoff = 0). Exporters can then zap ptes by unmapping the
|
|
* corresponding range of the struct address_space associated with their
|
|
* own file.
|
|
*
|
|
* This callback is optional.
|
|
*
|
|
* Returns:
|
|
*
|
|
* 0 on success or a negative error code on failure.
|
|
*/
|
|
int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
|
|
|
|
/**
|
|
* @map:
|
|
*
|
|
* Maps a page from the buffer into kernel address space. The page is
|
|
* specified by offset into the buffer in PAGE_SIZE units.
|
|
*
|
|
* This callback is optional.
|
|
*
|
|
* Returns:
|
|
*
|
|
* Virtual address pointer where requested page can be accessed. NULL
|
|
* on error or when this function is unimplemented by the exporter.
|
|
*/
|
|
void *(*map)(struct dma_buf *, unsigned long);
|
|
|
|
/**
|
|
* @unmap:
|
|
*
|
|
* Unmaps a page from the buffer. Page offset and address pointer should
|
|
* be the same as the one passed to and returned by matching call to map.
|
|
*
|
|
* This callback is optional.
|
|
*/
|
|
void (*unmap)(struct dma_buf *, unsigned long, void *);
|
|
|
|
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.
|
|
* @lock: used internally to serialize list manipulation, attach/detach and
|
|
* vmap/unmap, and accesses to name
|
|
* @vmapping_counter: used internally to refcnt the vmaps
|
|
* @vmap_ptr: the current vmap ptr if vmapping_counter > 0
|
|
* @exp_name: name of the exporter; useful for debugging.
|
|
* @name: userspace-provided name; useful for accounting and debugging.
|
|
* @owner: pointer to exporter module; used for refcounting when exporter is a
|
|
* kernel module.
|
|
* @list_node: node for dma_buf accounting and debugging.
|
|
* @priv: exporter specific private data for this buffer object.
|
|
* @resv: reservation object linked to this dma-buf
|
|
* @poll: for userspace poll support
|
|
* @cb_excl: for userspace poll support
|
|
* @cb_shared: for userspace poll support
|
|
*
|
|
* This represents a shared buffer, created by calling dma_buf_export(). The
|
|
* userspace representation is a normal file descriptor, which can be created by
|
|
* calling dma_buf_fd().
|
|
*
|
|
* Shared dma buffers are reference counted using dma_buf_put() and
|
|
* get_dma_buf().
|
|
*
|
|
* Device DMA access is handled by the separate &struct dma_buf_attachment.
|
|
*/
|
|
struct dma_buf {
|
|
size_t size;
|
|
struct file *file;
|
|
struct list_head attachments;
|
|
const struct dma_buf_ops *ops;
|
|
struct mutex lock;
|
|
unsigned vmapping_counter;
|
|
void *vmap_ptr;
|
|
const char *exp_name;
|
|
const char *name;
|
|
struct module *owner;
|
|
struct list_head list_node;
|
|
void *priv;
|
|
struct dma_resv *resv;
|
|
|
|
/* poll support */
|
|
wait_queue_head_t poll;
|
|
|
|
struct dma_buf_poll_cb_t {
|
|
struct dma_fence_cb cb;
|
|
wait_queue_head_t *poll;
|
|
|
|
__poll_t active;
|
|
} cb_excl, cb_shared;
|
|
};
|
|
|
|
/**
|
|
* 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.
|
|
* @sgt: cached mapping.
|
|
* @dir: direction of cached mapping.
|
|
* @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.
|
|
*
|
|
* An attachment is created by calling dma_buf_attach(), and released again by
|
|
* calling dma_buf_detach(). The DMA mapping itself needed to initiate a
|
|
* transfer is created by dma_buf_map_attachment() and freed again by calling
|
|
* dma_buf_unmap_attachment().
|
|
*/
|
|
struct dma_buf_attachment {
|
|
struct dma_buf *dmabuf;
|
|
struct device *dev;
|
|
struct list_head node;
|
|
struct sg_table *sgt;
|
|
enum dma_data_direction dir;
|
|
void *priv;
|
|
};
|
|
|
|
/**
|
|
* struct dma_buf_export_info - holds information needed to export a dma_buf
|
|
* @exp_name: name of the exporter - useful for debugging.
|
|
* @owner: pointer to exporter module - used for refcounting kernel module
|
|
* @ops: Attach allocator-defined dma buf ops to the new buffer
|
|
* @size: Size of the buffer
|
|
* @flags: mode flags for the file
|
|
* @resv: reservation-object, NULL to allocate default one
|
|
* @priv: Attach private data of allocator to this buffer
|
|
*
|
|
* This structure holds the information required to export the buffer. Used
|
|
* with dma_buf_export() only.
|
|
*/
|
|
struct dma_buf_export_info {
|
|
const char *exp_name;
|
|
struct module *owner;
|
|
const struct dma_buf_ops *ops;
|
|
size_t size;
|
|
int flags;
|
|
struct dma_resv *resv;
|
|
void *priv;
|
|
};
|
|
|
|
/**
|
|
* DEFINE_DMA_BUF_EXPORT_INFO - helper macro for exporters
|
|
* @name: export-info name
|
|
*
|
|
* DEFINE_DMA_BUF_EXPORT_INFO macro defines the &struct dma_buf_export_info,
|
|
* zeroes it out and pre-populates exp_name in it.
|
|
*/
|
|
#define DEFINE_DMA_BUF_EXPORT_INFO(name) \
|
|
struct dma_buf_export_info name = { .exp_name = KBUILD_MODNAME, \
|
|
.owner = THIS_MODULE }
|
|
|
|
/**
|
|
* 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(const struct dma_buf_export_info *exp_info);
|
|
|
|
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,
|
|
enum dma_data_direction dir);
|
|
int dma_buf_end_cpu_access(struct dma_buf *dma_buf,
|
|
enum dma_data_direction dir);
|
|
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__ */
|