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.
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=========================================================================
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I. Overview
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This driver implements all currently defined RapidIO mport callback functions.
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It supports maintenance read and write operations, inbound and outbound RapidIO
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doorbells, inbound maintenance port-writes and RapidIO messaging.
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To generate SRIO maintenance transactions this driver uses one of Tsi721 DMA
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channels. This mechanism provides access to larger range of hop counts and
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destination IDs without need for changes in outbound window translation.
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RapidIO messaging support uses dedicated messaging channels for each mailbox.
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For inbound messages this driver uses destination ID matching to forward messages
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into the corresponding message queue. Messaging callbacks are implemented to be
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fully compatible with RIONET driver (Ethernet over RapidIO messaging services).
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II. Known problems
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None.
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III. DMA Engine Support
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Tsi721 mport driver supports DMA data transfers between local system memory and
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remote RapidIO devices. This functionality is implemented according to SLAVE
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mode API defined by common Linux kernel DMA Engine framework.
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Depending on system requirements RapidIO DMA operations can be included/excluded
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by setting CONFIG_RAPIDIO_DMA_ENGINE option. Tsi721 miniport driver uses seven
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out of eight available BDMA channels to support DMA data transfers.
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One BDMA channel is reserved for generation of maintenance read/write requests.
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If Tsi721 mport driver have been built with RAPIDIO_DMA_ENGINE support included,
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this driver will accept DMA-specific module parameter:
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"dma_desc_per_channel" - defines number of hardware buffer descriptors used by
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each BDMA channel of Tsi721 (by default - 128).
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IV. Version History
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1.1.0 - DMA operations re-worked to support data scatter/gather lists larger
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than hardware buffer descriptors ring.
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1.0.0 - Initial driver release.
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V. License
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-----------------------------------------------
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Copyright(c) 2011 Integrated Device Technology, Inc. All rights reserved.
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This program is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2 of the License, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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You should have received a copy of the GNU General Public License along with
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this program; if not, write to the Free Software Foundation, Inc.,
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59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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