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Diffstat (limited to 'kernel/net/irda/wrapper.c')
| -rw-r--r-- | kernel/net/irda/wrapper.c | 492 |
1 files changed, 492 insertions, 0 deletions
diff --git a/kernel/net/irda/wrapper.c b/kernel/net/irda/wrapper.c new file mode 100644 index 000000000..40a0f993b --- /dev/null +++ b/kernel/net/irda/wrapper.c @@ -0,0 +1,492 @@ +/********************************************************************* + * + * 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 + */ + pr_debug("%s(), wrong magic in skb!\n", __func__); + xbofs = 10; + } else + xbofs = cb->xbofs + cb->xbofs_delay; + + pr_debug("%s(), xbofs=%d\n", __func__, xbofs); + + /* Check that we never use more than 115 + 48 xbofs */ + if (xbofs > 163) { + pr_debug("%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)) { + net_err_ratelimited("%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 */ + pr_debug("%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); + + pr_debug("%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: + net_warn_ratelimited("%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 { + pr_debug("%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 { + pr_debug("%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); + |