'\" t
.\"     Title: struct dma_buf_ops
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: January 2017
.\"    Manual: Device drivers infrastructure
.\"    Source: Kernel Hackers Manual 4.8.15
.\"  Language: English
.\"
.TH "STRUCT DMA_BUF_OPS" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "Device drivers infrastructure"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
struct_dma_buf_ops \- operations possible on struct dma_buf
.SH "SYNOPSIS"
.sp
.nf
struct dma_buf_ops {
  int (* attach) (struct dma_buf *, struct device *,struct dma_buf_attachment *);
  void (* detach) (struct dma_buf *, struct dma_buf_attachment *);
  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);
  void (* release) (struct dma_buf *);
  int (* begin_cpu_access) (struct dma_buf *, enum dma_data_direction);
  int (* end_cpu_access) (struct dma_buf *, 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);
};  
.fi
.SH "MEMBERS"
.PP
attach
.RS 4
[optional] allows different devices to \*(Aqattach\*(Aq 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\&.
.RE
.PP
detach
.RS 4
[optional] detach a given device from this buffer\&.
.RE
.PP
map_dma_buf
.RS 4
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\*(Aqt been called yet\&.
.RE
.PP
unmap_dma_buf
.RS 4
decreases usecount of buffer, might deallocate scatter pages\&.
.RE
.PP
release
.RS 4
release this buffer; to be called after the last dma_buf_put\&.
.RE
.PP
begin_cpu_access
.RS 4
[optional] called before cpu access to invalidate cpu caches and allocate backing storage (if not yet done) respectively pin the object into memory\&.
.RE
.PP
end_cpu_access
.RS 4
[optional] called after cpu access to flush caches\&.
.RE
.PP
kmap_atomic
.RS 4
maps a page from the buffer into kernel address space, users may not block until the subsequent unmap call\&. This callback must not sleep\&.
.RE
.PP
kunmap_atomic
.RS 4
[optional] unmaps a atomically mapped page from the buffer\&. This Callback must not sleep\&.
.RE
.PP
kmap
.RS 4
maps a page from the buffer into kernel address space\&.
.RE
.PP
kunmap
.RS 4
[optional] unmaps a page from the buffer\&.
.RE
.PP
mmap
.RS 4
used to expose the backing storage to userspace\&. Note that the mapping needs to be coherent \- if the exporter doesn\*(Aqt directly support this, it needs to fake coherency by shooting down any ptes when transitioning away from the cpu domain\&.
.RE
.PP
vmap
.RS 4
[optional] creates a virtual mapping for the buffer into kernel address space\&. Same restrictions as for vmap and friends apply\&.
.RE
.PP
vunmap
.RS 4
[optional] unmaps a vmap from the buffer
.RE
.SH "COPYRIGHT"
.br