493 lines
13 KiB
C
493 lines
13 KiB
C
/*********************************************************************
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*
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* Filename: wrapper.c
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* Version: 1.2
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* Description: IrDA SIR async wrapper layer
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* Status: Stable
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* Author: Dag Brattli <dagb@cs.uit.no>
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* Created at: Mon Aug 4 20:40:53 1997
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* Modified at: Fri Jan 28 13:21:09 2000
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* Modified by: Dag Brattli <dagb@cs.uit.no>
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* Modified at: Fri May 28 3:11 CST 1999
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* Modified by: Horst von Brand <vonbrand@sleipnir.valparaiso.cl>
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*
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* Copyright (c) 1998-2000 Dag Brattli <dagb@cs.uit.no>,
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* All Rights Reserved.
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* Copyright (c) 2000-2002 Jean Tourrilhes <jt@hpl.hp.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* Neither Dag Brattli nor University of Tromsø admit liability nor
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* provide warranty for any of this software. This material is
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* provided "AS-IS" and at no charge.
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*
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********************************************************************/
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#include <linux/skbuff.h>
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#include <linux/string.h>
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#include <linux/module.h>
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#include <asm/byteorder.h>
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#include <net/irda/irda.h>
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#include <net/irda/wrapper.h>
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#include <net/irda/crc.h>
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#include <net/irda/irlap.h>
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#include <net/irda/irlap_frame.h>
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#include <net/irda/irda_device.h>
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/************************** FRAME WRAPPING **************************/
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/*
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* Unwrap and unstuff SIR frames
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*
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* Note : at FIR and MIR, HDLC framing is used and usually handled
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* by the controller, so we come here only for SIR... Jean II
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*/
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/*
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* Function stuff_byte (byte, buf)
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*
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* Byte stuff one single byte and put the result in buffer pointed to by
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* buf. The buffer must at all times be able to have two bytes inserted.
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*
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* This is in a tight loop, better inline it, so need to be prior to callers.
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* (2000 bytes on P6 200MHz, non-inlined ~370us, inline ~170us) - Jean II
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*/
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static inline int stuff_byte(__u8 byte, __u8 *buf)
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{
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switch (byte) {
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case BOF: /* FALLTHROUGH */
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case EOF: /* FALLTHROUGH */
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case CE:
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/* Insert transparently coded */
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buf[0] = CE; /* Send link escape */
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buf[1] = byte^IRDA_TRANS; /* Complement bit 5 */
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return 2;
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/* break; */
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default:
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/* Non-special value, no transparency required */
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buf[0] = byte;
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return 1;
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/* break; */
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}
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}
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/*
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* Function async_wrap (skb, *tx_buff, buffsize)
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*
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* Makes a new buffer with wrapping and stuffing, should check that
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* we don't get tx buffer overflow.
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*/
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int async_wrap_skb(struct sk_buff *skb, __u8 *tx_buff, int buffsize)
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{
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struct irda_skb_cb *cb = (struct irda_skb_cb *) skb->cb;
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int xbofs;
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int i;
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int n;
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union {
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__u16 value;
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__u8 bytes[2];
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} fcs;
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/* Initialize variables */
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fcs.value = INIT_FCS;
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n = 0;
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/*
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* Send XBOF's for required min. turn time and for the negotiated
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* additional XBOFS
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*/
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if (cb->magic != LAP_MAGIC) {
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/*
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* This will happen for all frames sent from user-space.
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* Nothing to worry about, but we set the default number of
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* BOF's
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*/
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IRDA_DEBUG(1, "%s(), wrong magic in skb!\n", __func__);
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xbofs = 10;
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} else
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xbofs = cb->xbofs + cb->xbofs_delay;
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IRDA_DEBUG(4, "%s(), xbofs=%d\n", __func__, xbofs);
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/* Check that we never use more than 115 + 48 xbofs */
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if (xbofs > 163) {
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IRDA_DEBUG(0, "%s(), too many xbofs (%d)\n", __func__,
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xbofs);
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xbofs = 163;
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}
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memset(tx_buff + n, XBOF, xbofs);
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n += xbofs;
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/* Start of packet character BOF */
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tx_buff[n++] = BOF;
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/* Insert frame and calc CRC */
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for (i=0; i < skb->len; i++) {
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/*
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* Check for the possibility of tx buffer overflow. We use
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* bufsize-5 since the maximum number of bytes that can be
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* transmitted after this point is 5.
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*/
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if(n >= (buffsize-5)) {
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IRDA_ERROR("%s(), tx buffer overflow (n=%d)\n",
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__func__, n);
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return n;
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}
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n += stuff_byte(skb->data[i], tx_buff+n);
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fcs.value = irda_fcs(fcs.value, skb->data[i]);
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}
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/* Insert CRC in little endian format (LSB first) */
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fcs.value = ~fcs.value;
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#ifdef __LITTLE_ENDIAN
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n += stuff_byte(fcs.bytes[0], tx_buff+n);
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n += stuff_byte(fcs.bytes[1], tx_buff+n);
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#else /* ifdef __BIG_ENDIAN */
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n += stuff_byte(fcs.bytes[1], tx_buff+n);
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n += stuff_byte(fcs.bytes[0], tx_buff+n);
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#endif
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tx_buff[n++] = EOF;
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return n;
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}
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EXPORT_SYMBOL(async_wrap_skb);
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/************************* FRAME UNWRAPPING *************************/
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/*
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* Unwrap and unstuff SIR frames
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*
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* Complete rewrite by Jean II :
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* More inline, faster, more compact, more logical. Jean II
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* (16 bytes on P6 200MHz, old 5 to 7 us, new 4 to 6 us)
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* (24 bytes on P6 200MHz, old 9 to 10 us, new 7 to 8 us)
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* (for reference, 115200 b/s is 1 byte every 69 us)
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* And reduce wrapper.o by ~900B in the process ;-)
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*
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* Then, we have the addition of ZeroCopy, which is optional
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* (i.e. the driver must initiate it) and improve final processing.
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* (2005 B frame + EOF on P6 200MHz, without 30 to 50 us, with 10 to 25 us)
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*
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* Note : at FIR and MIR, HDLC framing is used and usually handled
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* by the controller, so we come here only for SIR... Jean II
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*/
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/*
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* We can also choose where we want to do the CRC calculation. We can
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* do it "inline", as we receive the bytes, or "postponed", when
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* receiving the End-Of-Frame.
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* (16 bytes on P6 200MHz, inlined 4 to 6 us, postponed 4 to 5 us)
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* (24 bytes on P6 200MHz, inlined 7 to 8 us, postponed 5 to 7 us)
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* With ZeroCopy :
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* (2005 B frame on P6 200MHz, inlined 10 to 25 us, postponed 140 to 180 us)
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* Without ZeroCopy :
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* (2005 B frame on P6 200MHz, inlined 30 to 50 us, postponed 150 to 180 us)
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* (Note : numbers taken with irq disabled)
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*
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* From those numbers, it's not clear which is the best strategy, because
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* we end up running through a lot of data one way or another (i.e. cache
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* misses). I personally prefer to avoid the huge latency spike of the
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* "postponed" solution, because it come just at the time when we have
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* lot's of protocol processing to do and it will hurt our ability to
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* reach low link turnaround times... Jean II
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*/
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//#define POSTPONE_RX_CRC
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/*
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* Function async_bump (buf, len, stats)
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*
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* Got a frame, make a copy of it, and pass it up the stack! We can try
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* to inline it since it's only called from state_inside_frame
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*/
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static inline void
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async_bump(struct net_device *dev,
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struct net_device_stats *stats,
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iobuff_t *rx_buff)
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{
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struct sk_buff *newskb;
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struct sk_buff *dataskb;
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int docopy;
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/* Check if we need to copy the data to a new skb or not.
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* If the driver doesn't use ZeroCopy Rx, we have to do it.
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* With ZeroCopy Rx, the rx_buff already point to a valid
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* skb. But, if the frame is small, it is more efficient to
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* copy it to save memory (copy will be fast anyway - that's
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* called Rx-copy-break). Jean II */
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docopy = ((rx_buff->skb == NULL) ||
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(rx_buff->len < IRDA_RX_COPY_THRESHOLD));
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/* Allocate a new skb */
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newskb = dev_alloc_skb(docopy ? rx_buff->len + 1 : rx_buff->truesize);
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if (!newskb) {
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stats->rx_dropped++;
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/* We could deliver the current skb if doing ZeroCopy Rx,
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* but this would stall the Rx path. Better drop the
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* packet... Jean II */
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return;
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}
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/* Align IP header to 20 bytes (i.e. increase skb->data)
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* Note this is only useful with IrLAN, as PPP has a variable
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* header size (2 or 1 bytes) - Jean II */
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skb_reserve(newskb, 1);
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if(docopy) {
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/* Copy data without CRC (length already checked) */
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skb_copy_to_linear_data(newskb, rx_buff->data,
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rx_buff->len - 2);
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/* Deliver this skb */
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dataskb = newskb;
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} else {
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/* We are using ZeroCopy. Deliver old skb */
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dataskb = rx_buff->skb;
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/* And hook the new skb to the rx_buff */
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rx_buff->skb = newskb;
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rx_buff->head = newskb->data; /* NOT newskb->head */
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//printk(KERN_DEBUG "ZeroCopy : len = %d, dataskb = %p, newskb = %p\n", rx_buff->len, dataskb, newskb);
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}
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/* Set proper length on skb (without CRC) */
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skb_put(dataskb, rx_buff->len - 2);
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/* Feed it to IrLAP layer */
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dataskb->dev = dev;
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skb_reset_mac_header(dataskb);
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dataskb->protocol = htons(ETH_P_IRDA);
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netif_rx(dataskb);
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stats->rx_packets++;
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stats->rx_bytes += rx_buff->len;
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/* Clean up rx_buff (redundant with async_unwrap_bof() ???) */
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rx_buff->data = rx_buff->head;
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rx_buff->len = 0;
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}
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/*
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* Function async_unwrap_bof(dev, byte)
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*
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* Handle Beginning Of Frame character received within a frame
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*
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*/
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static inline void
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async_unwrap_bof(struct net_device *dev,
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struct net_device_stats *stats,
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iobuff_t *rx_buff, __u8 byte)
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{
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switch(rx_buff->state) {
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case LINK_ESCAPE:
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case INSIDE_FRAME:
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/* Not supposed to happen, the previous frame is not
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* finished - Jean II */
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IRDA_DEBUG(1, "%s(), Discarding incomplete frame\n",
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__func__);
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stats->rx_errors++;
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stats->rx_missed_errors++;
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irda_device_set_media_busy(dev, TRUE);
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break;
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case OUTSIDE_FRAME:
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case BEGIN_FRAME:
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default:
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/* We may receive multiple BOF at the start of frame */
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break;
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}
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/* Now receiving frame */
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rx_buff->state = BEGIN_FRAME;
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rx_buff->in_frame = TRUE;
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/* Time to initialize receive buffer */
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rx_buff->data = rx_buff->head;
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rx_buff->len = 0;
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rx_buff->fcs = INIT_FCS;
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}
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/*
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* Function async_unwrap_eof(dev, byte)
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*
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* Handle End Of Frame character received within a frame
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*
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*/
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static inline void
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async_unwrap_eof(struct net_device *dev,
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struct net_device_stats *stats,
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iobuff_t *rx_buff, __u8 byte)
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{
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#ifdef POSTPONE_RX_CRC
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int i;
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#endif
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switch(rx_buff->state) {
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case OUTSIDE_FRAME:
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/* Probably missed the BOF */
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stats->rx_errors++;
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stats->rx_missed_errors++;
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irda_device_set_media_busy(dev, TRUE);
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break;
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case BEGIN_FRAME:
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case LINK_ESCAPE:
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case INSIDE_FRAME:
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default:
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/* Note : in the case of BEGIN_FRAME and LINK_ESCAPE,
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* the fcs will most likely not match and generate an
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* error, as expected - Jean II */
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rx_buff->state = OUTSIDE_FRAME;
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rx_buff->in_frame = FALSE;
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#ifdef POSTPONE_RX_CRC
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/* If we haven't done the CRC as we receive bytes, we
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* must do it now... Jean II */
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for(i = 0; i < rx_buff->len; i++)
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rx_buff->fcs = irda_fcs(rx_buff->fcs,
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rx_buff->data[i]);
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#endif
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/* Test FCS and signal success if the frame is good */
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if (rx_buff->fcs == GOOD_FCS) {
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/* Deliver frame */
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async_bump(dev, stats, rx_buff);
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break;
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} else {
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/* Wrong CRC, discard frame! */
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irda_device_set_media_busy(dev, TRUE);
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IRDA_DEBUG(1, "%s(), crc error\n", __func__);
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stats->rx_errors++;
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stats->rx_crc_errors++;
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}
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break;
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}
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}
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/*
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* Function async_unwrap_ce(dev, byte)
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*
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* Handle Character Escape character received within a frame
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*
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*/
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static inline void
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async_unwrap_ce(struct net_device *dev,
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struct net_device_stats *stats,
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iobuff_t *rx_buff, __u8 byte)
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{
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switch(rx_buff->state) {
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case OUTSIDE_FRAME:
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/* Activate carrier sense */
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irda_device_set_media_busy(dev, TRUE);
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break;
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case LINK_ESCAPE:
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IRDA_WARNING("%s: state not defined\n", __func__);
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break;
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case BEGIN_FRAME:
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case INSIDE_FRAME:
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default:
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/* Stuffed byte coming */
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rx_buff->state = LINK_ESCAPE;
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break;
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}
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}
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/*
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* Function async_unwrap_other(dev, byte)
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*
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* Handle other characters received within a frame
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*
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*/
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static inline void
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async_unwrap_other(struct net_device *dev,
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struct net_device_stats *stats,
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iobuff_t *rx_buff, __u8 byte)
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{
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switch(rx_buff->state) {
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/* This is on the critical path, case are ordered by
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* probability (most frequent first) - Jean II */
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case INSIDE_FRAME:
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/* Must be the next byte of the frame */
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if (rx_buff->len < rx_buff->truesize) {
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rx_buff->data[rx_buff->len++] = byte;
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#ifndef POSTPONE_RX_CRC
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rx_buff->fcs = irda_fcs(rx_buff->fcs, byte);
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#endif
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} else {
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IRDA_DEBUG(1, "%s(), Rx buffer overflow, aborting\n",
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__func__);
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rx_buff->state = OUTSIDE_FRAME;
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}
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break;
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case LINK_ESCAPE:
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/*
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* Stuffed char, complement bit 5 of byte
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* following CE, IrLAP p.114
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*/
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byte ^= IRDA_TRANS;
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if (rx_buff->len < rx_buff->truesize) {
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rx_buff->data[rx_buff->len++] = byte;
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#ifndef POSTPONE_RX_CRC
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rx_buff->fcs = irda_fcs(rx_buff->fcs, byte);
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#endif
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rx_buff->state = INSIDE_FRAME;
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} else {
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IRDA_DEBUG(1, "%s(), Rx buffer overflow, aborting\n",
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__func__);
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rx_buff->state = OUTSIDE_FRAME;
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}
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break;
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case OUTSIDE_FRAME:
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/* Activate carrier sense */
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if(byte != XBOF)
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irda_device_set_media_busy(dev, TRUE);
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break;
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case BEGIN_FRAME:
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default:
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rx_buff->data[rx_buff->len++] = byte;
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#ifndef POSTPONE_RX_CRC
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rx_buff->fcs = irda_fcs(rx_buff->fcs, byte);
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#endif
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rx_buff->state = INSIDE_FRAME;
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break;
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}
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}
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/*
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* Function async_unwrap_char (dev, rx_buff, byte)
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*
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* Parse and de-stuff frame received from the IrDA-port
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*
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* This is the main entry point for SIR drivers.
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*/
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void async_unwrap_char(struct net_device *dev,
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struct net_device_stats *stats,
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iobuff_t *rx_buff, __u8 byte)
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{
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switch(byte) {
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case CE:
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async_unwrap_ce(dev, stats, rx_buff, byte);
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break;
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case BOF:
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async_unwrap_bof(dev, stats, rx_buff, byte);
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break;
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case EOF:
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async_unwrap_eof(dev, stats, rx_buff, byte);
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break;
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default:
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async_unwrap_other(dev, stats, rx_buff, byte);
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break;
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}
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}
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EXPORT_SYMBOL(async_unwrap_char);
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