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972 lines
23 KiB
972 lines
23 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* 6pack.c This module implements the 6pack protocol for kernel-based |
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* devices like TTY. It interfaces between a raw TTY and the |
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* kernel's AX.25 protocol layers. |
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* |
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* Authors: Andreas Könsgen <[email protected]> |
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* Ralf Baechle DL5RB <[email protected]> |
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* |
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* Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by |
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* |
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* Laurence Culhane, <[email protected]> |
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* Fred N. van Kempen, <[email protected]> |
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*/ |
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|
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#include <linux/module.h> |
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#include <linux/uaccess.h> |
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#include <linux/bitops.h> |
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#include <linux/string.h> |
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#include <linux/mm.h> |
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#include <linux/interrupt.h> |
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#include <linux/in.h> |
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#include <linux/tty.h> |
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#include <linux/errno.h> |
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#include <linux/netdevice.h> |
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#include <linux/timer.h> |
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#include <linux/slab.h> |
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#include <net/ax25.h> |
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#include <linux/etherdevice.h> |
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#include <linux/skbuff.h> |
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#include <linux/rtnetlink.h> |
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#include <linux/spinlock.h> |
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#include <linux/if_arp.h> |
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#include <linux/init.h> |
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#include <linux/ip.h> |
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#include <linux/tcp.h> |
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#include <linux/semaphore.h> |
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#include <linux/refcount.h> |
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|
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#define SIXPACK_VERSION "Revision: 0.3.0" |
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|
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/* sixpack priority commands */ |
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#define SIXP_SEOF 0x40 /* start and end of a 6pack frame */ |
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#define SIXP_TX_URUN 0x48 /* transmit overrun */ |
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#define SIXP_RX_ORUN 0x50 /* receive overrun */ |
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#define SIXP_RX_BUF_OVL 0x58 /* receive buffer overflow */ |
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|
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#define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */ |
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|
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/* masks to get certain bits out of the status bytes sent by the TNC */ |
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|
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#define SIXP_CMD_MASK 0xC0 |
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#define SIXP_CHN_MASK 0x07 |
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#define SIXP_PRIO_CMD_MASK 0x80 |
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#define SIXP_STD_CMD_MASK 0x40 |
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#define SIXP_PRIO_DATA_MASK 0x38 |
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#define SIXP_TX_MASK 0x20 |
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#define SIXP_RX_MASK 0x10 |
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#define SIXP_RX_DCD_MASK 0x18 |
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#define SIXP_LEDS_ON 0x78 |
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#define SIXP_LEDS_OFF 0x60 |
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#define SIXP_CON 0x08 |
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#define SIXP_STA 0x10 |
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|
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#define SIXP_FOUND_TNC 0xe9 |
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#define SIXP_CON_ON 0x68 |
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#define SIXP_DCD_MASK 0x08 |
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#define SIXP_DAMA_OFF 0 |
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|
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/* default level 2 parameters */ |
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#define SIXP_TXDELAY 25 /* 250 ms */ |
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#define SIXP_PERSIST 50 /* in 256ths */ |
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#define SIXP_SLOTTIME 10 /* 100 ms */ |
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#define SIXP_INIT_RESYNC_TIMEOUT (3*HZ/2) /* in 1 s */ |
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#define SIXP_RESYNC_TIMEOUT 5*HZ /* in 1 s */ |
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|
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/* 6pack configuration. */ |
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#define SIXP_NRUNIT 31 /* MAX number of 6pack channels */ |
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#define SIXP_MTU 256 /* Default MTU */ |
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|
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enum sixpack_flags { |
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SIXPF_ERROR, /* Parity, etc. error */ |
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}; |
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|
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struct sixpack { |
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/* Various fields. */ |
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struct tty_struct *tty; /* ptr to TTY structure */ |
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struct net_device *dev; /* easy for intr handling */ |
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|
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/* These are pointers to the malloc()ed frame buffers. */ |
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unsigned char *rbuff; /* receiver buffer */ |
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int rcount; /* received chars counter */ |
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unsigned char *xbuff; /* transmitter buffer */ |
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unsigned char *xhead; /* next byte to XMIT */ |
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int xleft; /* bytes left in XMIT queue */ |
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|
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unsigned char raw_buf[4]; |
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unsigned char cooked_buf[400]; |
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|
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unsigned int rx_count; |
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unsigned int rx_count_cooked; |
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|
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int mtu; /* Our mtu (to spot changes!) */ |
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int buffsize; /* Max buffers sizes */ |
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|
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unsigned long flags; /* Flag values/ mode etc */ |
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unsigned char mode; /* 6pack mode */ |
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|
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/* 6pack stuff */ |
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unsigned char tx_delay; |
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unsigned char persistence; |
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unsigned char slottime; |
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unsigned char duplex; |
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unsigned char led_state; |
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unsigned char status; |
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unsigned char status1; |
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unsigned char status2; |
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unsigned char tx_enable; |
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unsigned char tnc_state; |
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|
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struct timer_list tx_t; |
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struct timer_list resync_t; |
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refcount_t refcnt; |
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struct completion dead; |
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spinlock_t lock; |
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}; |
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|
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#define AX25_6PACK_HEADER_LEN 0 |
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|
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static void sixpack_decode(struct sixpack *, const unsigned char[], int); |
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static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char); |
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|
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/* |
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* Perform the persistence/slottime algorithm for CSMA access. If the |
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* persistence check was successful, write the data to the serial driver. |
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* Note that in case of DAMA operation, the data is not sent here. |
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*/ |
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|
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static void sp_xmit_on_air(struct timer_list *t) |
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{ |
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struct sixpack *sp = from_timer(sp, t, tx_t); |
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int actual, when = sp->slottime; |
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static unsigned char random; |
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|
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random = random * 17 + 41; |
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if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) { |
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sp->led_state = 0x70; |
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sp->tty->ops->write(sp->tty, &sp->led_state, 1); |
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sp->tx_enable = 1; |
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actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2); |
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sp->xleft -= actual; |
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sp->xhead += actual; |
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sp->led_state = 0x60; |
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sp->tty->ops->write(sp->tty, &sp->led_state, 1); |
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sp->status2 = 0; |
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} else |
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mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100); |
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} |
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|
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/* ----> 6pack timer interrupt handler and friends. <---- */ |
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|
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/* Encapsulate one AX.25 frame and stuff into a TTY queue. */ |
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static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len) |
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{ |
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unsigned char *msg, *p = icp; |
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int actual, count; |
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|
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if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */ |
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msg = "oversized transmit packet!"; |
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goto out_drop; |
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} |
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|
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if (p[0] > 5) { |
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msg = "invalid KISS command"; |
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goto out_drop; |
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} |
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|
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if ((p[0] != 0) && (len > 2)) { |
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msg = "KISS control packet too long"; |
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goto out_drop; |
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} |
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|
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if ((p[0] == 0) && (len < 15)) { |
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msg = "bad AX.25 packet to transmit"; |
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goto out_drop; |
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} |
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|
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count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay); |
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set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags); |
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|
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switch (p[0]) { |
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case 1: sp->tx_delay = p[1]; |
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return; |
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case 2: sp->persistence = p[1]; |
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return; |
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case 3: sp->slottime = p[1]; |
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return; |
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case 4: /* ignored */ |
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return; |
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case 5: sp->duplex = p[1]; |
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return; |
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} |
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|
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if (p[0] != 0) |
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return; |
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|
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/* |
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* In case of fullduplex or DAMA operation, we don't take care about the |
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* state of the DCD or of any timers, as the determination of the |
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* correct time to send is the job of the AX.25 layer. We send |
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* immediately after data has arrived. |
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*/ |
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if (sp->duplex == 1) { |
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sp->led_state = 0x70; |
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sp->tty->ops->write(sp->tty, &sp->led_state, 1); |
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sp->tx_enable = 1; |
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actual = sp->tty->ops->write(sp->tty, sp->xbuff, count); |
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sp->xleft = count - actual; |
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sp->xhead = sp->xbuff + actual; |
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sp->led_state = 0x60; |
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sp->tty->ops->write(sp->tty, &sp->led_state, 1); |
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} else { |
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sp->xleft = count; |
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sp->xhead = sp->xbuff; |
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sp->status2 = count; |
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sp_xmit_on_air(&sp->tx_t); |
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} |
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|
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return; |
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|
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out_drop: |
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sp->dev->stats.tx_dropped++; |
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netif_start_queue(sp->dev); |
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if (net_ratelimit()) |
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printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg); |
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} |
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|
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/* Encapsulate an IP datagram and kick it into a TTY queue. */ |
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|
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static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev) |
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{ |
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struct sixpack *sp = netdev_priv(dev); |
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|
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if (skb->protocol == htons(ETH_P_IP)) |
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return ax25_ip_xmit(skb); |
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|
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spin_lock_bh(&sp->lock); |
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/* We were not busy, so we are now... :-) */ |
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netif_stop_queue(dev); |
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dev->stats.tx_bytes += skb->len; |
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sp_encaps(sp, skb->data, skb->len); |
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spin_unlock_bh(&sp->lock); |
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dev_kfree_skb(skb); |
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|
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return NETDEV_TX_OK; |
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} |
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static int sp_open_dev(struct net_device *dev) |
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{ |
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struct sixpack *sp = netdev_priv(dev); |
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|
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if (sp->tty == NULL) |
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return -ENODEV; |
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return 0; |
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} |
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|
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/* Close the low-level part of the 6pack channel. */ |
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static int sp_close(struct net_device *dev) |
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{ |
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struct sixpack *sp = netdev_priv(dev); |
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|
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spin_lock_bh(&sp->lock); |
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if (sp->tty) { |
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/* TTY discipline is running. */ |
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clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags); |
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} |
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netif_stop_queue(dev); |
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spin_unlock_bh(&sp->lock); |
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|
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return 0; |
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} |
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|
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static int sp_set_mac_address(struct net_device *dev, void *addr) |
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{ |
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struct sockaddr_ax25 *sa = addr; |
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|
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netif_tx_lock_bh(dev); |
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netif_addr_lock(dev); |
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memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN); |
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netif_addr_unlock(dev); |
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netif_tx_unlock_bh(dev); |
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|
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return 0; |
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} |
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static const struct net_device_ops sp_netdev_ops = { |
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.ndo_open = sp_open_dev, |
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.ndo_stop = sp_close, |
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.ndo_start_xmit = sp_xmit, |
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.ndo_set_mac_address = sp_set_mac_address, |
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}; |
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static void sp_setup(struct net_device *dev) |
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{ |
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/* Finish setting up the DEVICE info. */ |
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dev->netdev_ops = &sp_netdev_ops; |
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dev->needs_free_netdev = true; |
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dev->mtu = SIXP_MTU; |
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dev->hard_header_len = AX25_MAX_HEADER_LEN; |
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dev->header_ops = &ax25_header_ops; |
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dev->addr_len = AX25_ADDR_LEN; |
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dev->type = ARPHRD_AX25; |
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dev->tx_queue_len = 10; |
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|
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/* Only activated in AX.25 mode */ |
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memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); |
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memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN); |
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dev->flags = 0; |
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} |
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|
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/* Send one completely decapsulated IP datagram to the IP layer. */ |
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|
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/* |
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* This is the routine that sends the received data to the kernel AX.25. |
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* 'cmd' is the KISS command. For AX.25 data, it is zero. |
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*/ |
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|
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static void sp_bump(struct sixpack *sp, char cmd) |
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{ |
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struct sk_buff *skb; |
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int count; |
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unsigned char *ptr; |
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count = sp->rcount + 1; |
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|
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sp->dev->stats.rx_bytes += count; |
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|
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if ((skb = dev_alloc_skb(count + 1)) == NULL) |
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goto out_mem; |
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|
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ptr = skb_put(skb, count + 1); |
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*ptr++ = cmd; /* KISS command */ |
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|
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memcpy(ptr, sp->cooked_buf + 1, count); |
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skb->protocol = ax25_type_trans(skb, sp->dev); |
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netif_rx(skb); |
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sp->dev->stats.rx_packets++; |
|
|
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return; |
|
|
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out_mem: |
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sp->dev->stats.rx_dropped++; |
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} |
|
|
|
|
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/* ----------------------------------------------------------------------- */ |
|
|
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/* |
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* We have a potential race on dereferencing tty->disc_data, because the tty |
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* layer provides no locking at all - thus one cpu could be running |
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* sixpack_receive_buf while another calls sixpack_close, which zeroes |
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* tty->disc_data and frees the memory that sixpack_receive_buf is using. The |
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* best way to fix this is to use a rwlock in the tty struct, but for now we |
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* use a single global rwlock for all ttys in ppp line discipline. |
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*/ |
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static DEFINE_RWLOCK(disc_data_lock); |
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|
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static struct sixpack *sp_get(struct tty_struct *tty) |
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{ |
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struct sixpack *sp; |
|
|
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read_lock(&disc_data_lock); |
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sp = tty->disc_data; |
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if (sp) |
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refcount_inc(&sp->refcnt); |
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read_unlock(&disc_data_lock); |
|
|
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return sp; |
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} |
|
|
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static void sp_put(struct sixpack *sp) |
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{ |
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if (refcount_dec_and_test(&sp->refcnt)) |
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complete(&sp->dead); |
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} |
|
|
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/* |
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* Called by the TTY driver when there's room for more data. If we have |
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* more packets to send, we send them here. |
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*/ |
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static void sixpack_write_wakeup(struct tty_struct *tty) |
|
{ |
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struct sixpack *sp = sp_get(tty); |
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int actual; |
|
|
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if (!sp) |
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return; |
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if (sp->xleft <= 0) { |
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/* Now serial buffer is almost free & we can start |
|
* transmission of another packet */ |
|
sp->dev->stats.tx_packets++; |
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clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
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sp->tx_enable = 0; |
|
netif_wake_queue(sp->dev); |
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goto out; |
|
} |
|
|
|
if (sp->tx_enable) { |
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actual = tty->ops->write(tty, sp->xhead, sp->xleft); |
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sp->xleft -= actual; |
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sp->xhead += actual; |
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} |
|
|
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out: |
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sp_put(sp); |
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} |
|
|
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/* ----------------------------------------------------------------------- */ |
|
|
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/* |
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* Handle the 'receiver data ready' interrupt. |
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* This function is called by the tty module in the kernel when |
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* a block of 6pack data has been received, which can now be decapsulated |
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* and sent on to some IP layer for further processing. |
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*/ |
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static void sixpack_receive_buf(struct tty_struct *tty, |
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const unsigned char *cp, const char *fp, int count) |
|
{ |
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struct sixpack *sp; |
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int count1; |
|
|
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if (!count) |
|
return; |
|
|
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sp = sp_get(tty); |
|
if (!sp) |
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return; |
|
|
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/* Read the characters out of the buffer */ |
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count1 = count; |
|
while (count) { |
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count--; |
|
if (fp && *fp++) { |
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if (!test_and_set_bit(SIXPF_ERROR, &sp->flags)) |
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sp->dev->stats.rx_errors++; |
|
continue; |
|
} |
|
} |
|
sixpack_decode(sp, cp, count1); |
|
|
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sp_put(sp); |
|
tty_unthrottle(tty); |
|
} |
|
|
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/* |
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* Try to resync the TNC. Called by the resync timer defined in |
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* decode_prio_command |
|
*/ |
|
|
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#define TNC_UNINITIALIZED 0 |
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#define TNC_UNSYNC_STARTUP 1 |
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#define TNC_UNSYNCED 2 |
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#define TNC_IN_SYNC 3 |
|
|
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static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state) |
|
{ |
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char *msg; |
|
|
|
switch (new_tnc_state) { |
|
default: /* gcc oh piece-o-crap ... */ |
|
case TNC_UNSYNC_STARTUP: |
|
msg = "Synchronizing with TNC"; |
|
break; |
|
case TNC_UNSYNCED: |
|
msg = "Lost synchronization with TNC\n"; |
|
break; |
|
case TNC_IN_SYNC: |
|
msg = "Found TNC"; |
|
break; |
|
} |
|
|
|
sp->tnc_state = new_tnc_state; |
|
printk(KERN_INFO "%s: %s\n", sp->dev->name, msg); |
|
} |
|
|
|
static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state) |
|
{ |
|
int old_tnc_state = sp->tnc_state; |
|
|
|
if (old_tnc_state != new_tnc_state) |
|
__tnc_set_sync_state(sp, new_tnc_state); |
|
} |
|
|
|
static void resync_tnc(struct timer_list *t) |
|
{ |
|
struct sixpack *sp = from_timer(sp, t, resync_t); |
|
static char resync_cmd = 0xe8; |
|
|
|
/* clear any data that might have been received */ |
|
|
|
sp->rx_count = 0; |
|
sp->rx_count_cooked = 0; |
|
|
|
/* reset state machine */ |
|
|
|
sp->status = 1; |
|
sp->status1 = 1; |
|
sp->status2 = 0; |
|
|
|
/* resync the TNC */ |
|
|
|
sp->led_state = 0x60; |
|
sp->tty->ops->write(sp->tty, &sp->led_state, 1); |
|
sp->tty->ops->write(sp->tty, &resync_cmd, 1); |
|
|
|
|
|
/* Start resync timer again -- the TNC might be still absent */ |
|
mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT); |
|
} |
|
|
|
static inline int tnc_init(struct sixpack *sp) |
|
{ |
|
unsigned char inbyte = 0xe8; |
|
|
|
tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP); |
|
|
|
sp->tty->ops->write(sp->tty, &inbyte, 1); |
|
|
|
mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT); |
|
|
|
return 0; |
|
} |
|
|
|
/* |
|
* Open the high-level part of the 6pack channel. |
|
* This function is called by the TTY module when the |
|
* 6pack line discipline is called for. Because we are |
|
* sure the tty line exists, we only have to link it to |
|
* a free 6pcack channel... |
|
*/ |
|
static int sixpack_open(struct tty_struct *tty) |
|
{ |
|
char *rbuff = NULL, *xbuff = NULL; |
|
struct net_device *dev; |
|
struct sixpack *sp; |
|
unsigned long len; |
|
int err = 0; |
|
|
|
if (!capable(CAP_NET_ADMIN)) |
|
return -EPERM; |
|
if (tty->ops->write == NULL) |
|
return -EOPNOTSUPP; |
|
|
|
dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN, |
|
sp_setup); |
|
if (!dev) { |
|
err = -ENOMEM; |
|
goto out; |
|
} |
|
|
|
sp = netdev_priv(dev); |
|
sp->dev = dev; |
|
|
|
spin_lock_init(&sp->lock); |
|
refcount_set(&sp->refcnt, 1); |
|
init_completion(&sp->dead); |
|
|
|
/* !!! length of the buffers. MTU is IP MTU, not PACLEN! */ |
|
|
|
len = dev->mtu * 2; |
|
|
|
rbuff = kmalloc(len + 4, GFP_KERNEL); |
|
xbuff = kmalloc(len + 4, GFP_KERNEL); |
|
|
|
if (rbuff == NULL || xbuff == NULL) { |
|
err = -ENOBUFS; |
|
goto out_free; |
|
} |
|
|
|
spin_lock_bh(&sp->lock); |
|
|
|
sp->tty = tty; |
|
|
|
sp->rbuff = rbuff; |
|
sp->xbuff = xbuff; |
|
|
|
sp->mtu = AX25_MTU + 73; |
|
sp->buffsize = len; |
|
sp->rcount = 0; |
|
sp->rx_count = 0; |
|
sp->rx_count_cooked = 0; |
|
sp->xleft = 0; |
|
|
|
sp->flags = 0; /* Clear ESCAPE & ERROR flags */ |
|
|
|
sp->duplex = 0; |
|
sp->tx_delay = SIXP_TXDELAY; |
|
sp->persistence = SIXP_PERSIST; |
|
sp->slottime = SIXP_SLOTTIME; |
|
sp->led_state = 0x60; |
|
sp->status = 1; |
|
sp->status1 = 1; |
|
sp->status2 = 0; |
|
sp->tx_enable = 0; |
|
|
|
netif_start_queue(dev); |
|
|
|
timer_setup(&sp->tx_t, sp_xmit_on_air, 0); |
|
|
|
timer_setup(&sp->resync_t, resync_tnc, 0); |
|
|
|
spin_unlock_bh(&sp->lock); |
|
|
|
/* Done. We have linked the TTY line to a channel. */ |
|
tty->disc_data = sp; |
|
tty->receive_room = 65536; |
|
|
|
/* Now we're ready to register. */ |
|
err = register_netdev(dev); |
|
if (err) |
|
goto out_free; |
|
|
|
tnc_init(sp); |
|
|
|
return 0; |
|
|
|
out_free: |
|
kfree(xbuff); |
|
kfree(rbuff); |
|
|
|
free_netdev(dev); |
|
|
|
out: |
|
return err; |
|
} |
|
|
|
|
|
/* |
|
* Close down a 6pack channel. |
|
* This means flushing out any pending queues, and then restoring the |
|
* TTY line discipline to what it was before it got hooked to 6pack |
|
* (which usually is TTY again). |
|
*/ |
|
static void sixpack_close(struct tty_struct *tty) |
|
{ |
|
struct sixpack *sp; |
|
|
|
write_lock_irq(&disc_data_lock); |
|
sp = tty->disc_data; |
|
tty->disc_data = NULL; |
|
write_unlock_irq(&disc_data_lock); |
|
if (!sp) |
|
return; |
|
|
|
/* |
|
* We have now ensured that nobody can start using ap from now on, but |
|
* we have to wait for all existing users to finish. |
|
*/ |
|
if (!refcount_dec_and_test(&sp->refcnt)) |
|
wait_for_completion(&sp->dead); |
|
|
|
/* We must stop the queue to avoid potentially scribbling |
|
* on the free buffers. The sp->dead completion is not sufficient |
|
* to protect us from sp->xbuff access. |
|
*/ |
|
netif_stop_queue(sp->dev); |
|
|
|
del_timer_sync(&sp->tx_t); |
|
del_timer_sync(&sp->resync_t); |
|
|
|
/* Free all 6pack frame buffers. */ |
|
kfree(sp->rbuff); |
|
kfree(sp->xbuff); |
|
|
|
unregister_netdev(sp->dev); |
|
} |
|
|
|
/* Perform I/O control on an active 6pack channel. */ |
|
static int sixpack_ioctl(struct tty_struct *tty, struct file *file, |
|
unsigned int cmd, unsigned long arg) |
|
{ |
|
struct sixpack *sp = sp_get(tty); |
|
struct net_device *dev; |
|
unsigned int tmp, err; |
|
|
|
if (!sp) |
|
return -ENXIO; |
|
dev = sp->dev; |
|
|
|
switch(cmd) { |
|
case SIOCGIFNAME: |
|
err = copy_to_user((void __user *) arg, dev->name, |
|
strlen(dev->name) + 1) ? -EFAULT : 0; |
|
break; |
|
|
|
case SIOCGIFENCAP: |
|
err = put_user(0, (int __user *) arg); |
|
break; |
|
|
|
case SIOCSIFENCAP: |
|
if (get_user(tmp, (int __user *) arg)) { |
|
err = -EFAULT; |
|
break; |
|
} |
|
|
|
sp->mode = tmp; |
|
dev->addr_len = AX25_ADDR_LEN; |
|
dev->hard_header_len = AX25_KISS_HEADER_LEN + |
|
AX25_MAX_HEADER_LEN + 3; |
|
dev->type = ARPHRD_AX25; |
|
|
|
err = 0; |
|
break; |
|
|
|
case SIOCSIFHWADDR: { |
|
char addr[AX25_ADDR_LEN]; |
|
|
|
if (copy_from_user(&addr, |
|
(void __user *)arg, AX25_ADDR_LEN)) { |
|
err = -EFAULT; |
|
break; |
|
} |
|
|
|
netif_tx_lock_bh(dev); |
|
memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN); |
|
netif_tx_unlock_bh(dev); |
|
err = 0; |
|
break; |
|
} |
|
default: |
|
err = tty_mode_ioctl(tty, file, cmd, arg); |
|
} |
|
|
|
sp_put(sp); |
|
|
|
return err; |
|
} |
|
|
|
static struct tty_ldisc_ops sp_ldisc = { |
|
.owner = THIS_MODULE, |
|
.num = N_6PACK, |
|
.name = "6pack", |
|
.open = sixpack_open, |
|
.close = sixpack_close, |
|
.ioctl = sixpack_ioctl, |
|
.receive_buf = sixpack_receive_buf, |
|
.write_wakeup = sixpack_write_wakeup, |
|
}; |
|
|
|
/* Initialize 6pack control device -- register 6pack line discipline */ |
|
|
|
static const char msg_banner[] __initconst = KERN_INFO \ |
|
"AX.25: 6pack driver, " SIXPACK_VERSION "\n"; |
|
static const char msg_regfail[] __initconst = KERN_ERR \ |
|
"6pack: can't register line discipline (err = %d)\n"; |
|
|
|
static int __init sixpack_init_driver(void) |
|
{ |
|
int status; |
|
|
|
printk(msg_banner); |
|
|
|
/* Register the provided line protocol discipline */ |
|
status = tty_register_ldisc(&sp_ldisc); |
|
if (status) |
|
printk(msg_regfail, status); |
|
|
|
return status; |
|
} |
|
|
|
static void __exit sixpack_exit_driver(void) |
|
{ |
|
tty_unregister_ldisc(&sp_ldisc); |
|
} |
|
|
|
/* encode an AX.25 packet into 6pack */ |
|
|
|
static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw, |
|
int length, unsigned char tx_delay) |
|
{ |
|
int count = 0; |
|
unsigned char checksum = 0, buf[400]; |
|
int raw_count = 0; |
|
|
|
tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK; |
|
tx_buf_raw[raw_count++] = SIXP_SEOF; |
|
|
|
buf[0] = tx_delay; |
|
for (count = 1; count < length; count++) |
|
buf[count] = tx_buf[count]; |
|
|
|
for (count = 0; count < length; count++) |
|
checksum += buf[count]; |
|
buf[length] = (unsigned char) 0xff - checksum; |
|
|
|
for (count = 0; count <= length; count++) { |
|
if ((count % 3) == 0) { |
|
tx_buf_raw[raw_count++] = (buf[count] & 0x3f); |
|
tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30); |
|
} else if ((count % 3) == 1) { |
|
tx_buf_raw[raw_count++] |= (buf[count] & 0x0f); |
|
tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c); |
|
} else { |
|
tx_buf_raw[raw_count++] |= (buf[count] & 0x03); |
|
tx_buf_raw[raw_count++] = (buf[count] >> 2); |
|
} |
|
} |
|
if ((length % 3) != 2) |
|
raw_count++; |
|
tx_buf_raw[raw_count++] = SIXP_SEOF; |
|
return raw_count; |
|
} |
|
|
|
/* decode 4 sixpack-encoded bytes into 3 data bytes */ |
|
|
|
static void decode_data(struct sixpack *sp, unsigned char inbyte) |
|
{ |
|
unsigned char *buf; |
|
|
|
if (sp->rx_count != 3) { |
|
sp->raw_buf[sp->rx_count++] = inbyte; |
|
|
|
return; |
|
} |
|
|
|
if (sp->rx_count_cooked + 2 >= sizeof(sp->cooked_buf)) { |
|
pr_err("6pack: cooked buffer overrun, data loss\n"); |
|
sp->rx_count = 0; |
|
return; |
|
} |
|
|
|
buf = sp->raw_buf; |
|
sp->cooked_buf[sp->rx_count_cooked++] = |
|
buf[0] | ((buf[1] << 2) & 0xc0); |
|
sp->cooked_buf[sp->rx_count_cooked++] = |
|
(buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0); |
|
sp->cooked_buf[sp->rx_count_cooked++] = |
|
(buf[2] & 0x03) | (inbyte << 2); |
|
sp->rx_count = 0; |
|
} |
|
|
|
/* identify and execute a 6pack priority command byte */ |
|
|
|
static void decode_prio_command(struct sixpack *sp, unsigned char cmd) |
|
{ |
|
int actual; |
|
|
|
if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */ |
|
|
|
/* RX and DCD flags can only be set in the same prio command, |
|
if the DCD flag has been set without the RX flag in the previous |
|
prio command. If DCD has not been set before, something in the |
|
transmission has gone wrong. In this case, RX and DCD are |
|
cleared in order to prevent the decode_data routine from |
|
reading further data that might be corrupt. */ |
|
|
|
if (((sp->status & SIXP_DCD_MASK) == 0) && |
|
((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) { |
|
if (sp->status != 1) |
|
printk(KERN_DEBUG "6pack: protocol violation\n"); |
|
else |
|
sp->status = 0; |
|
cmd &= ~SIXP_RX_DCD_MASK; |
|
} |
|
sp->status = cmd & SIXP_PRIO_DATA_MASK; |
|
} else { /* output watchdog char if idle */ |
|
if ((sp->status2 != 0) && (sp->duplex == 1)) { |
|
sp->led_state = 0x70; |
|
sp->tty->ops->write(sp->tty, &sp->led_state, 1); |
|
sp->tx_enable = 1; |
|
actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2); |
|
sp->xleft -= actual; |
|
sp->xhead += actual; |
|
sp->led_state = 0x60; |
|
sp->status2 = 0; |
|
|
|
} |
|
} |
|
|
|
/* needed to trigger the TNC watchdog */ |
|
sp->tty->ops->write(sp->tty, &sp->led_state, 1); |
|
|
|
/* if the state byte has been received, the TNC is present, |
|
so the resync timer can be reset. */ |
|
|
|
if (sp->tnc_state == TNC_IN_SYNC) |
|
mod_timer(&sp->resync_t, jiffies + SIXP_INIT_RESYNC_TIMEOUT); |
|
|
|
sp->status1 = cmd & SIXP_PRIO_DATA_MASK; |
|
} |
|
|
|
/* identify and execute a standard 6pack command byte */ |
|
|
|
static void decode_std_command(struct sixpack *sp, unsigned char cmd) |
|
{ |
|
unsigned char checksum = 0, rest = 0; |
|
short i; |
|
|
|
switch (cmd & SIXP_CMD_MASK) { /* normal command */ |
|
case SIXP_SEOF: |
|
if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) { |
|
if ((sp->status & SIXP_RX_DCD_MASK) == |
|
SIXP_RX_DCD_MASK) { |
|
sp->led_state = 0x68; |
|
sp->tty->ops->write(sp->tty, &sp->led_state, 1); |
|
} |
|
} else { |
|
sp->led_state = 0x60; |
|
/* fill trailing bytes with zeroes */ |
|
sp->tty->ops->write(sp->tty, &sp->led_state, 1); |
|
rest = sp->rx_count; |
|
if (rest != 0) |
|
for (i = rest; i <= 3; i++) |
|
decode_data(sp, 0); |
|
if (rest == 2) |
|
sp->rx_count_cooked -= 2; |
|
else if (rest == 3) |
|
sp->rx_count_cooked -= 1; |
|
for (i = 0; i < sp->rx_count_cooked; i++) |
|
checksum += sp->cooked_buf[i]; |
|
if (checksum != SIXP_CHKSUM) { |
|
printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum); |
|
} else { |
|
sp->rcount = sp->rx_count_cooked-2; |
|
sp_bump(sp, 0); |
|
} |
|
sp->rx_count_cooked = 0; |
|
} |
|
break; |
|
case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n"); |
|
break; |
|
case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n"); |
|
break; |
|
case SIXP_RX_BUF_OVL: |
|
printk(KERN_DEBUG "6pack: RX buffer overflow\n"); |
|
} |
|
} |
|
|
|
/* decode a 6pack packet */ |
|
|
|
static void |
|
sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count) |
|
{ |
|
unsigned char inbyte; |
|
int count1; |
|
|
|
for (count1 = 0; count1 < count; count1++) { |
|
inbyte = pre_rbuff[count1]; |
|
if (inbyte == SIXP_FOUND_TNC) { |
|
tnc_set_sync_state(sp, TNC_IN_SYNC); |
|
del_timer(&sp->resync_t); |
|
} |
|
if ((inbyte & SIXP_PRIO_CMD_MASK) != 0) |
|
decode_prio_command(sp, inbyte); |
|
else if ((inbyte & SIXP_STD_CMD_MASK) != 0) |
|
decode_std_command(sp, inbyte); |
|
else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK) |
|
decode_data(sp, inbyte); |
|
} |
|
} |
|
|
|
MODULE_AUTHOR("Ralf Baechle DO1GRB <[email protected]>"); |
|
MODULE_DESCRIPTION("6pack driver for AX.25"); |
|
MODULE_LICENSE("GPL"); |
|
MODULE_ALIAS_LDISC(N_6PACK); |
|
|
|
module_init(sixpack_init_driver); |
|
module_exit(sixpack_exit_driver);
|
|
|