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marcus.erl |
/* nicstar.c v0.22 Jawaid Bazyar (bazyar@hypermall.com)
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* nicstar.c, M. Welsh (matt.welsh@cl.cam.ac.uk)
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*
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* Hacked October, 1997 by Jawaid Bazyar, Interlink Advertising Services Inc.
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* http://www.hypermall.com/
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* 10/1/97 - commented out CFG_PHYIE bit - we don't care when the PHY
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* interrupts us (except possibly for removal/insertion of the cable?)
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* 10/4/97 - began heavy inline documentation of the code. Corrected typos
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* and spelling mistakes.
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* 10/5/97 - added code to handle PHY interrupts, disable PHY on
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* loss of link, and correctly re-enable PHY when link is
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* re-established. (put back CFG_PHYIE)
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*
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* Modified to work with the IDT7721 nicstar -- AAL5 (tested) only.
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*
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* R. D. Rechenmacher , Aug. 6, 1997 $Revision: 1.1 $ $Date: 1999/08/20 11:00:11 $
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*
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* Linux driver for the IDT77201 NICStAR PCI ATM controller.
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* PHY component is expected to be 155 Mbps S/UNI-Lite or IDT 77155;
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* see init_nicstar() for PHY initialization to change this. This driver
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* expects the Linux ATM stack to support scatter-gather lists
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* (skb->atm.iovcnt != 0) for Rx skb's passed to vcc->push.
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*
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* Implementing minimal-copy of received data:
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* IDT always receives data into a small buffer, then large buffers
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* as needed. This means that data must always be copied to create
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* the linear buffer needed by most non-ATM protocol stacks (e.g. IP)
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* Fix is simple: make large buffers large enough to hold entire
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* SDU, and leave bytes empty at the start. Then
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* copy small buffer contents to head of large buffer.
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* Trick is to avoid fragmenting Linux, due to need for a lot of large
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* buffers. This is done by 2 things:
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* 1) skb->destructor / skb->atm.recycle_buffer
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* combined, allow nicstar_free_rx_skb to be called to
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* recycle large data buffers
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* 2) skb_clone of received buffers
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* See nicstar_free_rx_skb and linearize_buffer for implementation
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* details.
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*
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*
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*
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* Copyright (c) 1996 University of Cambridge Computer Laboratory
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* M. Welsh, 6 July 1996
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*
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*
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*/
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