1/* nicstar.c v0.22 Jawaid Bazyar (bazyar@hypermall.com) 2 * nicstar.c, M. Welsh (matt.welsh@cl.cam.ac.uk) 3 * 4 * Hacked October, 1997 by Jawaid Bazyar, Interlink Advertising Services Inc. 5 * http://www.hypermall.com/ 6 * 10/1/97 - commented out CFG_PHYIE bit - we don't care when the PHY 7 * interrupts us (except possibly for removal/insertion of the cable?) 8 * 10/4/97 - began heavy inline documentation of the code. Corrected typos 9 * and spelling mistakes. 10 * 10/5/97 - added code to handle PHY interrupts, disable PHY on 11 * loss of link, and correctly re-enable PHY when link is 12 * re-established. (put back CFG_PHYIE) 13 * 14 * Modified to work with the IDT7721 nicstar -- AAL5 (tested) only. 15 * 16 * R. D. Rechenmacher <ron@fnal.gov>, Aug. 6, 1997 17 * 18 * Linux driver for the IDT77201 NICStAR PCI ATM controller. 19 * PHY component is expected to be 155 Mbps S/UNI-Lite or IDT 77155; 20 * see init_nicstar() for PHY initialization to change this. This driver 21 * expects the Linux ATM stack to support scatter-gather lists 22 * (skb->atm.iovcnt != 0) for Rx skb's passed to vcc->push. 23 * 24 * Implementing minimal-copy of received data: 25 * IDT always receives data into a small buffer, then large buffers 26 * as needed. This means that data must always be copied to create 27 * the linear buffer needed by most non-ATM protocol stacks (e.g. IP) 28 * Fix is simple: make large buffers large enough to hold entire 29 * SDU, and leave <small_buffer_data> bytes empty at the start. Then 30 * copy small buffer contents to head of large buffer. 31 * Trick is to avoid fragmenting Linux, due to need for a lot of large 32 * buffers. This is done by 2 things: 33 * 1) skb->destructor / skb->atm.recycle_buffer 34 * combined, allow nicstar_free_rx_skb to be called to 35 * recycle large data buffers 36 * 2) skb_clone of received buffers 37 * See nicstar_free_rx_skb and linearize_buffer for implementation 38 * details. 39 * 40 * 41 * 42 * Copyright (c) 1996 University of Cambridge Computer Laboratory 43 * 44 * This program is free software; you can redistribute it and/or modify 45 * it under the terms of the GNU General Public License as published by 46 * the Free Software Foundation; either version 2 of the License, or 47 * (at your option) any later version. 48 * 49 * This program is distributed in the hope that it will be useful, 50 * but WITHOUT ANY WARRANTY; without even the implied warranty of 51 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 52 * GNU General Public License for more details. 53 * 54 * You should have received a copy of the GNU General Public License 55 * along with this program; if not, write to the Free Software 56 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 57 * 58 * M. Welsh, 6 July 1996 59 * 60 * 61 */ 62