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staging: comedi: plx9080.h: Add kerneldoc comments

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Document the DMA descriptor `struct plx_dma_desc`, and the DMA abort
function `plx9080_abort_dma()`.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2016-05-20 14:49:21 +01:00 committed by Greg Kroah-Hartman
parent 457bec0f73
commit 6a64877f63
1 changed files with 29 additions and 6 deletions
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35
drivers/staging/comedi/drivers/plx9080.h
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@ -19,16 +19,27 @@
#ifndef __COMEDI_PLX9080_H
#define __COMEDI_PLX9080_H
/* descriptor block used for chained dma transfers */
/**
* struct plx_dma_desc - DMA descriptor format for PLX PCI 9080
* @pci_start_addr: PCI Bus address for transfer (DMAPADR).
* @local_start_addr: Local Bus address for transfer (DMALADR).
* @transfer_size: Transfer size in bytes (max 8 MiB) (DMASIZ).
* @next: Address of next descriptor + flags (DMADPR).
*
* Describes the format of a scatter-gather DMA descriptor for the PLX
* PCI 9080. All members are raw, little-endian register values that
* will be transferred by the DMA engine from local or PCI memory into
* corresponding registers for the DMA channel.
*
* The DMA descriptors must be aligned on a 16-byte boundary. Bits 3:0
* of @next contain flags describing the address space of the next
* descriptor (local or PCI), an "end of chain" marker, an "interrupt on
* terminal count" bit, and a data transfer direction.
*/
struct plx_dma_desc {
__le32 pci_start_addr;
__le32 local_start_addr;
/* transfer_size is in bytes, only first 23 bits of register are used */
__le32 transfer_size;
/*
* address of next descriptor (quad word aligned), plus some
* additional bits (see PLX_REG_DMADPR)
*/
__le32 next;
};
@ -594,6 +605,18 @@ struct plx_dma_desc {
#define PLX_PREFETCH 32
/**
* plx9080_abort_dma - Abort a PLX PCI 9080 DMA transfer
* @iobase: Remapped base address of configuration registers.
* @channel: DMA channel number (0 or 1).
*
* Aborts the DMA transfer on the channel, which must have been enabled
* and started beforehand.
*
* Return:
* %0 on success.
* -%ETIMEDOUT if timed out waiting for abort to complete.
*/
static inline int plx9080_abort_dma(void __iomem *iobase, unsigned int channel)
{
void __iomem *dma_cs_addr;