1 files changed, 491 insertions, 0 deletions

diff --git a/net/irda/wrapper.c b/net/irda/wrapper.c
new file mode 100644
index 000000000000..87130c1c8693
--- /dev/null
+++ 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 Tromsų 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", __FUNCTION__);
+                xbofs = 10;
+        } else
+                xbofs = cb->xbofs + cb->xbofs_delay;
+
+        IRDA_DEBUG(4, "%s(), xbofs=%d\n", __FUNCTION__, xbofs);
+
+        /* Check that we never use more than 115 + 48 xbofs */
+        if (xbofs > 163) {
+                IRDA_DEBUG(0, "%s(), too many xbofs (%d)\n", __FUNCTION__,
+                           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",
+                                   __FUNCTION__, 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 (lenght already checked) */
+                memcpy(newskb->data, 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;
+        dataskb->mac.raw  = dataskb->data;
+        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",
+                           __FUNCTION__);
+                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", __FUNCTION__);
+                        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", __FUNCTION__);
+                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",
+                                   __FUNCTION__);
+                        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",
+                                   __FUNCTION__);
+                        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);
+