* 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 *);
* @pin
*
* This is called by dma_buf_pin and lets the exporter know that the
* DMA-buf can't be moved any more.
*
* This is called with the dmabuf->resv object locked and is mutual
* exclusive with @cache_sgt_mapping.
*
* This callback is optional and should only be used in limited use
* cases like scanout and not for temporary pin operations.
*
* Returns
*
* 0 on success, negative error code on failure.
*/
int (*pin)(struct dma_buf_attachment *attach);
* @unpin
*
* This is called by dma_buf_unpin and lets the exporter know that the
* DMA-buf can be moved again.
*
* This is called with the dmabuf->resv object locked and is mutual
* exclusive with @cache_sgt_mapping.
*
* This callback is optional.
*/
void (*unpin)(struct dma_buf_attachment *attach);
* @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 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.
*
* This is always called with the dmabuf->resv object locked when
* the dynamic_mapping flag is true.
*
* 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.
* For static dma_buf handling this might also unpins the backing
* storage if this is the last mapping of the DMA buffer.
*/
void (*unmap_dma_buf)(struct dma_buf_attachment *, struct sg_table *, enum dma_data_direction);
* 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.
*
* 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);
* @begin_cpu_access_partial
*
* This is called from dma_buf_begin_cpu_access_partial() and allows the
* exporter to ensure that the memory specified in the range is
* 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.
*
* 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_partial)(struct dma_buf *dmabuf, enum dma_data_direction, unsigned int offset,
unsigned int len);
* @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);
* @end_cpu_access_partial
*
* This is called from dma_buf_end_cpu_access_partial() when the
* importer is done accessing the CPU. The exporter can use to limit
* cache flushing to only the range specefied and to unpin any
* resources pinned in @begin_cpu_access_umapped.
* The result of any dma_buf kmap calls after end_cpu_access_partial 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_partial)(struct dma_buf *dmabuf, enum dma_data_direction, unsigned int offset,
unsigned int len);
* @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);
void *(*vmap)(struct dma_buf *);
void (*vunmap)(struct dma_buf *, void *vaddr);
* @get_uuid
*
* This is called by dma_buf_get_uuid to get the UUID which identifies
* the buffer to virtio devices.
*
* This callback is optional.
*
* Returns
*
* 0 on success or a negative error code on failure. On success uuid
* will be populated with the buffer's UUID.
*/
int (*get_uuid)(struct dma_buf *dmabuf, uuid_t *uuid);
* @get_flags
*
* This is called by dma_buf_get_flags and is used to get the buffer's
* flags.
* This callback is optional.
*
* Returns
*
* 0 on success or a negative error code on failure. On success flags
* will be populated with the buffer's flags.
*/
int (*get_flags)(struct dma_buf *dmabuf, unsigned long *flags);
};
* 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,
* protected by dma_resv lock.
* @ops: dma_buf_ops associated with this buffer object.
* @lock: used internally to serialize list manipulation, attach/detach and
* vmap/unmap
* @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,
* protected by @resv.
* @name_lock: spinlock to protect name access
* @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
* @exp_pid: pid of exporter task which created this obj
* @exp_task_comm: process name of exporter task which created this obj
* @poll: for userspace poll support
* @cb_excl: for userspace poll support
* @cb_shared: for userspace poll support
* @sysfs_entry: for exposing information about this buffer in sysfs.
* @mmap_count: number of times buffer has been mmapped.
* @exp_vm_ops: the vm ops provided by the buffer exporter.
* @vm_ops: the overridden vm_ops used to track mmap_count of the buffer.
*
* 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;
spinlock_t name_lock;
struct module *owner;
struct list_head list_node;
void *priv;
struct dma_resv *resv;
#ifdef CONFIG_DMABUF_PROCESS_INFO
pid_t exp_pid;
char exp_task_comm[TASK_COMM_LEN];
#endif
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;
#ifdef CONFIG_DMABUF_SYSFS_STATS
struct dma_buf_sysfs_entry {
struct kobject kobj;
struct dma_buf *dmabuf;
} *sysfs_entry;
int mmap_count;
const struct vm_operations_struct *exp_vm_ops;
struct vm_operations_struct vm_ops;
#endif
};
* struct dma_buf_attach_ops - importer operations for an attachment
*
* Attachment operations implemented by the importer.
*/
struct dma_buf_attach_ops {
* @allow_peer2peer:
*
* If this is set to true the importer must be able to handle peer
* resources without struct pages.
*/
bool allow_peer2peer;
* @move_notify: [optional] notification that the DMA-buf is moving
*
* If this callback is provided the framework can avoid pinning the
* backing store while mappings exists.
*
* This callback is called with the lock of the reservation object
* associated with the dma_buf held and the mapping function must be
* called with this lock held as well. This makes sure that no mapping
* is created concurrently with an ongoing move operation.
*
* Mappings stay valid and are not directly affected by this callback.
* But the DMA-buf can now be in a different physical location, so all
* mappings should be destroyed and re-created as soon as possible.
*
* New mappings can be created after this callback returns, and will
* point to the new location of the DMA-buf.
*/
void (*move_notify)(struct dma_buf_attachment *attach);
};
* 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, protected by dma_resv lock of the dmabuf.
* @sgt: cached mapping.
* @dir: direction of cached mapping.
* @peer2peer: true if the importer can handle peer resources without pages.
* @priv: exporter specific attachment data.
* @importer_ops: importer operations for this attachment, if provided
* dma_buf_map/unmap_attachment() must be called with the dma_resv lock held.
* @importer_priv: importer specific attachment data.
* @dma_map_attrs: DMA attributes to be used when the exporter maps the buffer
* through dma_buf_map_attachment.
* @sysfs_entry: For exposing information about this attachment in sysfs.
*
* 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;
bool peer2peer;
const struct dma_buf_attach_ops *importer_ops;
void *importer_priv;
void *priv;
unsigned long dma_map_attrs;
#ifdef CONFIG_DMABUF_SYSFS_STATS
struct dma_buf_attach_sysfs_entry {
struct kobject kobj;
unsigned int map_counter;
} *sysfs_entry;
#endif
};
* 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);
}
* dma_buf_is_dynamic - check if a DMA-buf uses dynamic mappings.
* @dmabuf: the DMA-buf to check
*
* Returns true if a DMA-buf exporter wants to be called with the dma_resv
* locked for the map/unmap callbacks, false if it doesn't wants to be called
* with the lock held.
*/
static inline bool dma_buf_is_dynamic(struct dma_buf *dmabuf)
{
return !!dmabuf->ops->pin;
}
* dma_buf_attachment_is_dynamic - check if a DMA-buf attachment uses dynamic
* mappinsg
* @attach: the DMA-buf attachment to check
*
* Returns true if a DMA-buf importer wants to call the map/unmap functions with
* the dma_resv lock held.
*/
static inline bool dma_buf_attachment_is_dynamic(struct dma_buf_attachment *attach)
{
return !!attach->importer_ops;
}
int get_each_dmabuf(int (*callback)(const struct dma_buf *dmabuf, void *private), void *private);
int is_dma_buf_file(struct file *file);
struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, struct device *dev);
struct dma_buf_attachment *dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
const struct dma_buf_attach_ops *importer_ops, void *importer_priv);
void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach);
int dma_buf_pin(struct dma_buf_attachment *attach);
void dma_buf_unpin(struct dma_buf_attachment *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);
void dma_buf_move_notify(struct dma_buf *dma_buf);
int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction dir);
int dma_buf_begin_cpu_access_partial(struct dma_buf *dma_buf, enum dma_data_direction dir, unsigned int offset,
unsigned int len);
int dma_buf_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction dir);
int dma_buf_end_cpu_access_partial(struct dma_buf *dma_buf, enum dma_data_direction dir, unsigned int offset,
unsigned int len);
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_get_flags(struct dma_buf *dmabuf, unsigned long *flags);
int dma_buf_get_uuid(struct dma_buf *dmabuf, uuid_t *uuid);
#ifdef CONFIG_DMABUF_PROCESS_INFO
* get_dma_buf_from_file - Get struct dma_buf* from struct file*
* @f: [in] pointer to struct file, which is associated with a
* dma_buf object.
*
* If @f IS_ERR_OR_NULL, return NULL.
* If @f is not a file associated with dma_buf, return NULL.
*/
struct dma_buf *get_dma_buf_from_file(struct file *f);
#endif
#endif