diff options
Diffstat (limited to 'drivers/net/hamradio/6pack.c')
| -rw-r--r-- | drivers/net/hamradio/6pack.c | 1037 |
1 files changed, 1037 insertions, 0 deletions
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c new file mode 100644 index 00000000..64783a0d --- /dev/null +++ b/drivers/net/hamradio/6pack.c @@ -0,0 +1,1037 @@ +/* + * 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@comnets.uni-bremen.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/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 <linux/slab.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 <linux/compat.h> +#include <linux/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; + + 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 sixpack *sp, unsigned char *icp, int len) +{ + unsigned char *msg, *p = icp; + int actual, count; + + if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */ + msg = "oversized transmit packet!"; + goto out_drop; + } + + if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */ + msg = "oversized transmit packet!"; + goto out_drop; + } + + if (p[0] > 5) { + msg = "invalid KISS command"; + goto out_drop; + } + + if ((p[0] != 0) && (len > 2)) { + msg = "KISS control packet too long"; + goto out_drop; + } + + if ((p[0] == 0) && (len < 15)) { + msg = "bad AX.25 packet to transmit"; + goto out_drop; + } + + count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay); + set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags); + + switch (p[0]) { + case 1: sp->tx_delay = p[1]; + return; + case 2: sp->persistence = p[1]; + return; + case 3: sp->slottime = p[1]; + return; + case 4: /* ignored */ + return; + case 5: sp->duplex = p[1]; + return; + } + + if (p[0] != 0) + return; + + /* + * In case of fullduplex or DAMA operation, we don't take care about the + * state of the DCD or of any timers, as the determination of the + * correct time to send is the job of the AX.25 layer. We send + * immediately after data has arrived. + */ + if (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, count); + sp->xleft = count - actual; + sp->xhead = sp->xbuff + actual; + sp->led_state = 0x60; + sp->tty->ops->write(sp->tty, &sp->led_state, 1); + } else { + sp->xleft = count; + sp->xhead = sp->xbuff; + sp->status2 = count; + sp_xmit_on_air((unsigned long)sp); + } + + return; + +out_drop: + sp->dev->stats.tx_dropped++; + netif_start_queue(sp->dev); + if (net_ratelimit()) + printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg); +} + +/* Encapsulate an IP datagram and kick it into a TTY queue. */ + +static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev) +{ + struct sixpack *sp = netdev_priv(dev); + + spin_lock_bh(&sp->lock); + /* We were not busy, so we are now... :-) */ + netif_stop_queue(dev); + dev->stats.tx_bytes += skb->len; + sp_encaps(sp, skb->data, skb->len); + spin_unlock_bh(&sp->lock); + + dev_kfree_skb(skb); + + return NETDEV_TX_OK; +} + +static int sp_open_dev(struct net_device *dev) +{ + struct sixpack *sp = netdev_priv(dev); + + if (sp->tty == NULL) + return -ENODEV; + return 0; +} + +/* Close the low-level part of the 6pack channel. */ +static int sp_close(struct net_device *dev) +{ + struct sixpack *sp = netdev_priv(dev); + + spin_lock_bh(&sp->lock); + if (sp->tty) { + /* TTY discipline is running. */ + clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags); + } + netif_stop_queue(dev); + spin_unlock_bh(&sp->lock); + + return 0; +} + +/* Return the frame type ID */ +static int sp_header(struct sk_buff *skb, struct net_device *dev, + unsigned short type, const void *daddr, + const void *saddr, unsigned len) +{ +#ifdef CONFIG_INET + if (type != ETH_P_AX25) + return ax25_hard_header(skb, dev, type, daddr, saddr, len); +#endif + return 0; +} + +static int sp_set_mac_address(struct net_device *dev, void *addr) +{ + struct sockaddr_ax25 *sa = addr; + + netif_tx_lock_bh(dev); + netif_addr_lock(dev); + memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN); + netif_addr_unlock(dev); + netif_tx_unlock_bh(dev); + + return 0; +} + +static int sp_rebuild_header(struct sk_buff *skb) +{ +#ifdef CONFIG_INET + return ax25_rebuild_header(skb); +#else + return 0; +#endif +} + +static const struct header_ops sp_header_ops = { + .create = sp_header, + .rebuild = sp_rebuild_header, +}; + +static const struct net_device_ops sp_netdev_ops = { + .ndo_open = sp_open_dev, + .ndo_stop = sp_close, + .ndo_start_xmit = sp_xmit, + .ndo_set_mac_address = sp_set_mac_address, +}; + +static void sp_setup(struct net_device *dev) +{ + /* Finish setting up the DEVICE info. */ + dev->netdev_ops = &sp_netdev_ops; + dev->destructor = free_netdev; + dev->mtu = SIXP_MTU; + dev->hard_header_len = AX25_MAX_HEADER_LEN; + dev->header_ops = &sp_header_ops; + + dev->addr_len = AX25_ADDR_LEN; + dev->type = ARPHRD_AX25; + dev->tx_queue_len = 10; + + /* Only activated in AX.25 mode */ + memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); + memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN); + + dev->flags = 0; +} + +/* Send one completely decapsulated IP datagram to the IP layer. */ + +/* + * This is the routine that sends the received data to the kernel AX.25. + * 'cmd' is the KISS command. For AX.25 data, it is zero. + */ + +static void sp_bump(struct sixpack *sp, char cmd) +{ + struct sk_buff *skb; + int count; + unsigned char *ptr; + + count = sp->rcount + 1; + + sp->dev->stats.rx_bytes += count; + + if ((skb = dev_alloc_skb(count)) == NULL) + goto out_mem; + + ptr = skb_put(skb, count); + *ptr++ = cmd; /* KISS command */ + + memcpy(ptr, sp->cooked_buf + 1, count); + skb->protocol = ax25_type_trans(skb, sp->dev); + netif_rx(skb); + sp->dev->stats.rx_packets++; + + return; + +out_mem: + sp->dev->stats.rx_dropped++; +} + + +/* ----------------------------------------------------------------------- */ + +/* + * We have a potential race on dereferencing tty->disc_data, because the tty + * layer provides no locking at all - thus one cpu could be running + * sixpack_receive_buf while another calls sixpack_close, which zeroes + * tty->disc_data and frees the memory that sixpack_receive_buf is using. The + * best way to fix this is to use a rwlock in the tty struct, but for now we + * use a single global rwlock for all ttys in ppp line discipline. + */ +static DEFINE_RWLOCK(disc_data_lock); + +static struct sixpack *sp_get(struct tty_struct *tty) +{ + struct sixpack *sp; + + read_lock(&disc_data_lock); + sp = tty->disc_data; + if (sp) + atomic_inc(&sp->refcnt); + read_unlock(&disc_data_lock); + + return sp; +} + +static void sp_put(struct sixpack *sp) +{ + if (atomic_dec_and_test(&sp->refcnt)) + up(&sp->dead_sem); +} + +/* + * Called by the TTY driver when there's room for more data. If we have + * more packets to send, we send them here. + */ +static void sixpack_write_wakeup(struct tty_struct *tty) +{ + struct sixpack *sp = sp_get(tty); + int actual; + + if (!sp) + return; + if (sp->xleft <= 0) { + /* Now serial buffer is almost free & we can start + * transmission of another packet */ + sp->dev->stats.tx_packets++; + clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); + sp->tx_enable = 0; + netif_wake_queue(sp->dev); + goto out; + } + + if (sp->tx_enable) { + actual = tty->ops->write(tty, sp->xhead, sp->xleft); + sp->xleft -= actual; + sp->xhead += actual; + } + +out: + sp_put(sp); +} + +/* ----------------------------------------------------------------------- */ + +/* + * Handle the 'receiver data ready' interrupt. + * This function is called by the 'tty_io' module in the kernel when + * a block of 6pack data has been received, which can now be decapsulated + * and sent on to some IP layer for further processing. + */ +static void sixpack_receive_buf(struct tty_struct *tty, + const unsigned char *cp, char *fp, int count) +{ + struct sixpack *sp; + unsigned char buf[512]; + int count1; + + if (!count) + return; + + sp = sp_get(tty); + if (!sp) + return; + + memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf)); + + /* Read the characters out of the buffer */ + + count1 = count; + while (count) { + count--; + if (fp && *fp++) { + if (!test_and_set_bit(SIXPF_ERROR, &sp->flags)) + sp->dev->stats.rx_errors++; + continue; + } + } + sixpack_decode(sp, buf, count1); + + sp_put(sp); + tty_unthrottle(tty); +} + +/* + * Try to resync the TNC. Called by the resync timer defined in + * decode_prio_command + */ + +#define TNC_UNINITIALIZED 0 +#define TNC_UNSYNC_STARTUP 1 +#define TNC_UNSYNCED 2 +#define TNC_IN_SYNC 3 + +static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state) +{ + 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(unsigned long channel) +{ + struct sixpack *sp = (struct sixpack *) channel; + 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 */ + + del_timer(&sp->resync_t); + sp->resync_t.data = (unsigned long) sp; + sp->resync_t.function = resync_tnc; + sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT; + add_timer(&sp->resync_t); +} + +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); + + del_timer(&sp->resync_t); + sp->resync_t.data = (unsigned long) sp; + sp->resync_t.function = resync_tnc; + sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT; + add_timer(&sp->resync_t); + + 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", sp_setup); + if (!dev) { + err = -ENOMEM; + goto out; + } + + sp = netdev_priv(dev); + sp->dev = dev; + + spin_lock_init(&sp->lock); + atomic_set(&sp->refcnt, 1); + sema_init(&sp->dead_sem, 0); + + /* !!! 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); + + init_timer(&sp->tx_t); + sp->tx_t.function = sp_xmit_on_air; + sp->tx_t.data = (unsigned long) sp; + + init_timer(&sp->resync_t); + + 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. */ + if (register_netdev(dev)) + goto out_free; + + tnc_init(sp); + + return 0; + +out_free: + kfree(xbuff); + kfree(rbuff); + + if (dev) + 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_bh(&disc_data_lock); + sp = tty->disc_data; + tty->disc_data = NULL; + write_unlock_bh(&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 (!atomic_dec_and_test(&sp->refcnt)) + down(&sp->dead_sem); + + unregister_netdev(sp->dev); + + del_timer(&sp->tx_t); + del_timer(&sp->resync_t); + + /* Free all 6pack frame buffers. */ + kfree(sp->rbuff); + kfree(sp->xbuff); +} + +/* 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; +} + +#ifdef CONFIG_COMPAT +static long sixpack_compat_ioctl(struct tty_struct * tty, struct file * file, + unsigned int cmd, unsigned long arg) +{ + switch (cmd) { + case SIOCGIFNAME: + case SIOCGIFENCAP: + case SIOCSIFENCAP: + case SIOCSIFHWADDR: + return sixpack_ioctl(tty, file, cmd, + (unsigned long)compat_ptr(arg)); + } + + return -ENOIOCTLCMD; +} +#endif + +static struct tty_ldisc_ops sp_ldisc = { + .owner = THIS_MODULE, + .magic = TTY_LDISC_MAGIC, + .name = "6pack", + .open = sixpack_open, + .close = sixpack_close, + .ioctl = sixpack_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = sixpack_compat_ioctl, +#endif + .receive_buf = sixpack_receive_buf, + .write_wakeup = sixpack_write_wakeup, +}; + +/* Initialize 6pack control device -- register 6pack line discipline */ + +static const char msg_banner[] __initdata = KERN_INFO \ + "AX.25: 6pack driver, " SIXPACK_VERSION "\n"; +static const char msg_regfail[] __initdata = 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 */ + if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0) + printk(msg_regfail, status); + + return status; +} + +static const char msg_unregfail[] __exitdata = KERN_ERR \ + "6pack: can't unregister line discipline (err = %d)\n"; + +static void __exit sixpack_exit_driver(void) +{ + int ret; + + if ((ret = tty_unregister_ldisc(N_6PACK))) + printk(msg_unregfail, ret); +} + +/* 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; + } + + 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) +{ + unsigned char channel; + int actual; + + channel = cmd & SIXP_CHN_MASK; + 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) { + del_timer(&sp->resync_t); + sp->resync_t.data = (unsigned long) sp; + sp->resync_t.function = resync_tnc; + sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT; + add_timer(&sp->resync_t); + } + + 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, channel; + short i; + + channel = cmd & SIXP_CHN_MASK; + 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, 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 <ralf@linux-mips.org>"); +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); |