Commit 50835e97 authored by Alexandre Bounine's avatar Alexandre Bounine Committed by Linus Torvalds
Browse files

rapidio/tsi721_dma: rework scatter-gather list handling 



Rework Tsi721 RapidIO DMA engine support to allow handling data
scatter/gather lists longer than number of hardware buffer descriptors in
the DMA channel's descriptor list.

The current implementation of Tsi721 DMA transfers requires that number of
entries in a scatter/gather list provided by a caller of
dmaengine_prep_rio_sg() should not exceed number of allocated hardware
buffer descriptors.

This patch removes the limitation by processing long scatter/gather lists
by sections that can be transferred using hardware descriptor ring of
configured size.  It also introduces a module parameter
"dma_desc_per_channel" to allow run-time configuration of Tsi721 hardware
buffer descriptor rings.

Signed-off-by: default avatarAlexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Andre van Herk <andre.van.herk@prodrive-technologies.com>
Cc: Stef van Os <stef.van.os@prodrive-technologies.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4aff1ce7

Documentation/rapidio/tsi721.txt

+16 −3
Original line number Diff line number Diff line
@@ -20,13 +20,26 @@ II. Known problems 


  None.



III. To do

III. DMA Engine Support



 Add DMA data transfers (non-messaging).

 Add inbound region (SRIO-to-PCIe) mapping.

Tsi721 mport driver supports DMA data transfers between local system memory and

remote RapidIO devices. This functionality is implemented according to SLAVE

mode API defined by common Linux kernel DMA Engine framework.



Depending on system requirements RapidIO DMA operations can be included/excluded

by setting CONFIG_RAPIDIO_DMA_ENGINE option. Tsi721 miniport driver uses seven

out of eight available BDMA channels to support DMA data transfers.

One BDMA channel is reserved for generation of maintenance read/write requests.



If Tsi721 mport driver have been built with RAPIDIO_DMA_ENGINE support included,

this driver will accept DMA-specific module parameter:

  "dma_desc_per_channel" - defines number of hardware buffer descriptors used by

                           each BDMA channel of Tsi721 (by default - 128).



IV. Version History



  1.1.0 - DMA operations re-worked to support data scatter/gather lists larger

          than hardware buffer descriptors ring.

  1.0.0 - Initial driver release.



V.  License

drivers/rapidio/devices/tsi721.h

+5 −7
Original line number Diff line number Diff line
@@ -644,27 +644,26 @@ enum tsi721_smsg_int_flag { 


#ifdef CONFIG_RAPIDIO_DMA_ENGINE



#define TSI721_BDMA_BD_RING_SZ	128

#define TSI721_BDMA_MAX_BCOUNT	(TSI721_DMAD_BCOUNT1 + 1)



struct tsi721_tx_desc {

	struct dma_async_tx_descriptor	txd;

	struct tsi721_dma_desc		*hw_desc;

	u16				destid;

	/* low 64-bits of 66-bit RIO address */

	u64				rio_addr;

	/* upper 2-bits of 66-bit RIO address */

	u8				rio_addr_u;

	u32				bcount;

	bool				interrupt;

	enum dma_rtype			rtype;

	struct list_head		desc_node;

	struct list_head		tx_list;

	struct scatterlist		*sg;

	unsigned int			sg_len;

	enum dma_status			status;

};



struct tsi721_bdma_chan {

	int		id;

	void __iomem	*regs;

	int		bd_num;		/* number of buffer descriptors */

	int		bd_num;		/* number of HW buffer descriptors */

	void		*bd_base;	/* start of DMA descriptors */

	dma_addr_t	bd_phys;

	void		*sts_base;	/* start of DMA BD status FIFO */
@@ -680,7 +679,6 @@ struct tsi721_bdma_chan { 
	struct list_head	active_list;

	struct list_head	queue;

	struct list_head	free_list;

	dma_cookie_t		completed_cookie;

	struct tasklet_struct	tasklet;

	bool			active;

};

drivers/rapidio/devices/tsi721_dma.c

+373 −345

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