/*
* 6pack.c This module implements the 6pack protocol for kernel-based
* devices like TTY. It interfaces between a raw TTY and the
* kernel's AX.25 protocol layers.
*
* Authors: Andreas Könsgen <ajk@iehk.rwth-aachen.de>
* Ralf Baechle DL5RB <ralf@linux-mips.org>
*
* Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by
*
* Laurence Culhane, <loz@holmes.demon.co.uk>
* Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
*/
#include <linux/module.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <linux/bitops.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/timer.h>
#include <net/ax25.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/spinlock.h>
#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/semaphore.h>
#include <asm/atomic.h>
#define SIXPACK_VERSION "Revision: 0.3.0"
/* sixpack priority commands */
#define SIXP_SEOF 0x40 /* start and end of a 6pack frame */
#define SIXP_TX_URUN 0x48 /* transmit overrun */
#define SIXP_RX_ORUN 0x50 /* receive overrun */
#define SIXP_RX_BUF_OVL 0x58 /* receive buffer overflow */
#define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */
/* masks to get certain bits out of the status bytes sent by the TNC */
#define SIXP_CMD_MASK 0xC0
#define SIXP_CHN_MASK 0x07
#define SIXP_PRIO_CMD_MASK 0x80
#define SIXP_STD_CMD_MASK 0x40
#define SIXP_PRIO_DATA_MASK 0x38
#define SIXP_TX_MASK 0x20
#define SIXP_RX_MASK 0x10
#define SIXP_RX_DCD_MASK 0x18
#define SIXP_LEDS_ON 0x78
#define SIXP_LEDS_OFF 0x60
#define SIXP_CON 0x08
#define SIXP_STA 0x10
#define SIXP_FOUND_TNC 0xe9
#define SIXP_CON_ON 0x68
#define SIXP_DCD_MASK 0x08
#define SIXP_DAMA_OFF 0
/* default level 2 parameters */
#define SIXP_TXDELAY (HZ/4) /* in 1 s */
#define SIXP_PERSIST 50 /* in 256ths */
#define SIXP_SLOTTIME (HZ/10) /* in 1 s */
#define SIXP_INIT_RESYNC_TIMEOUT (3*HZ/2) /* in 1 s */
#define SIXP_RESYNC_TIMEOUT 5*HZ /* in 1 s */
/* 6pack configuration. */
#define SIXP_NRUNIT 31 /* MAX number of 6pack channels */
#define SIXP_MTU 256 /* Default MTU */
enum sixpack_flags {
SIXPF_ERROR, /* Parity, etc. error */
};
struct sixpack {
/* Various fields. */
struct tty_struct *tty; /* ptr to TTY structure */
struct net_device *dev; /* easy for intr handling */
/* These are pointers to the malloc()ed frame buffers. */
unsigned char *rbuff; /* receiver buffer */
int rcount; /* received chars counter */
unsigned char *xbuff; /* transmitter buffer */
unsigned char *xhead; /* next byte to XMIT */
int xleft; /* bytes left in XMIT queue */
unsigned char raw_buf[4];
unsigned char cooked_buf[400];
unsigned int rx_count;
unsigned int rx_count_cooked;
/* 6pack interface statistics. */
struct net_device_stats stats;
int mtu; /* Our mtu (to spot changes!) */
int buffsize; /* Max buffers sizes */
unsigned long flags; /* Flag values/ mode etc */
unsigned char mode; /* 6pack mode */
/* 6pack stuff */
unsigned char tx_delay;
unsigned char persistence;
unsigned char slottime;
unsigned char duplex;
unsigned char led_state;
unsigned char status;
unsigned char status1;
unsigned char status2;
unsigned char tx_enable;
unsigned char tnc_state;
struct timer_list tx_t;
struct timer_list resync_t;
atomic_t refcnt;
struct semaphore dead_sem;
spinlock_t lock;
};
#define AX25_6PACK_HEADER_LEN 0
static void sixpack_decode(struct sixpack *, unsigned char[], int);
static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
/*
* Perform the persistence/slottime algorithm for CSMA access. If the
* persistence check was successful, write the data to the serial driver.
* Note that in case of DAMA operation, the data is not sent here.
*/
static void sp_xmit_on_air(unsigned long channel)
{
struct sixpack *sp = (struct sixpack *) channel;
int actual, when = sp->slottime;
static unsigned char random;
random = random * 17 + 41;
if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
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->tty->ops->write(sp->tty, &sp->led_state, 1);
sp->status2 = 0;
} else
mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
}
/* ----> 6pack timer interrupt handler and friends. <---- */
/* Encapsulate one AX.25 frame and stuff into a TTY queue. */
static void sp_encaps(struct