mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-25 21:54:06 +08:00
50835e977b
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: Alexandre 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
63 lines
2.8 KiB
Plaintext
63 lines
2.8 KiB
Plaintext
RapidIO subsystem mport driver for IDT Tsi721 PCI Express-to-SRIO bridge.
|
|
=========================================================================
|
|
|
|
I. Overview
|
|
|
|
This driver implements all currently defined RapidIO mport callback functions.
|
|
It supports maintenance read and write operations, inbound and outbound RapidIO
|
|
doorbells, inbound maintenance port-writes and RapidIO messaging.
|
|
|
|
To generate SRIO maintenance transactions this driver uses one of Tsi721 DMA
|
|
channels. This mechanism provides access to larger range of hop counts and
|
|
destination IDs without need for changes in outbound window translation.
|
|
|
|
RapidIO messaging support uses dedicated messaging channels for each mailbox.
|
|
For inbound messages this driver uses destination ID matching to forward messages
|
|
into the corresponding message queue. Messaging callbacks are implemented to be
|
|
fully compatible with RIONET driver (Ethernet over RapidIO messaging services).
|
|
|
|
II. Known problems
|
|
|
|
None.
|
|
|
|
III. DMA Engine Support
|
|
|
|
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
|
|
-----------------------------------------------
|
|
|
|
Copyright(c) 2011 Integrated Device Technology, Inc. All rights reserved.
|
|
|
|
This program is free software; you can redistribute it and/or modify it
|
|
under the terms of the GNU General Public License as published by the Free
|
|
Software Foundation; either version 2 of the License, or (at your option)
|
|
any later version.
|
|
|
|
This program is distributed in the hope that it will be useful, but WITHOUT
|
|
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
|
|
more details.
|
|
|
|
You should have received a copy of the GNU General Public License along with
|
|
this program; if not, write to the Free Software Foundation, Inc.,
|
|
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|