initial_commit

1 files changed, 492 insertions, 0 deletions

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