diff options
author | Ian Abbott <abbotti@mev.co.uk> | 2015-09-21 18:52:52 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-09-29 03:25:03 +0200 |
commit | 11a10830b6e1ed001e0d71594beb5eedc714e202 (patch) | |
tree | 78338cc0e0dcacbd505df766fd7ca8ba672c1683 /drivers/staging/comedi/comedidev.h | |
parent | 0f952fa843397f9a08b937caf8fcc8126813d492 (diff) |
staging: comedi: comedidev.h: document struct comedi_buf_map
Add kernel-doc for `struct comedi_buf_map` and the associated `struct
comedi_buf_page`.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/comedi/comedidev.h')
-rw-r--r-- | drivers/staging/comedi/comedidev.h | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h index ccd761b7b150..cfb7d520d82f 100644 --- a/drivers/staging/comedi/comedidev.h +++ b/drivers/staging/comedi/comedidev.h @@ -217,11 +217,40 @@ struct comedi_subdevice { unsigned int *readback; }; +/** + * struct comedi_buf_page - Describe a page of a COMEDI buffer + * @virt_addr: Kernel address of page. + * @dma_addr: DMA address of page if in DMA coherent memory. + */ struct comedi_buf_page { void *virt_addr; dma_addr_t dma_addr; }; +/** + * struct comedi_buf_map - Describe pages in a COMEDI buffer + * @dma_hw_dev: Low-level hardware &struct device pointer copied from the + * COMEDI device's hw_dev member. + * @page_list: Pointer to array of &struct comedi_buf_page, one for each + * page in the buffer. + * @n_pages: Number of pages in the buffer. + * @dma_dir: DMA direction used to allocate pages of DMA coherent memory, + * or %DMA_NONE if pages allocated from regular memory. + * @refcount: &struct kref reference counter used to free the buffer. + * + * A COMEDI data buffer is allocated as individual pages, either in + * conventional memory or DMA coherent memory, depending on the attached, + * low-level hardware device. (The buffer pages also get mapped into the + * kernel's contiguous virtual address space pointed to by the 'prealloc_buf' + * member of &struct comedi_async.) + * + * The buffer is normally freed when the COMEDI device is detached from the + * low-level driver (which may happen due to device removal), but if it happens + * to be mmapped at the time, the pages cannot be freed until the buffer has + * been munmapped. That is what the reference counter is for. (The virtual + * address space pointed by 'prealloc_buf' is freed when the COMEDI device is + * detached.) + */ struct comedi_buf_map { struct device *dma_hw_dev; struct comedi_buf_page *page_list; |