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-rw-r--r--drivers/net/hamradio/6pack.c980
1 files changed, 980 insertions, 0 deletions
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
new file mode 100644
index 0000000000..6ed38a3cdd
--- /dev/null
+++ b/drivers/net/hamradio/6pack.c
@@ -0,0 +1,980 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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 <linux/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/refcount.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 25 /* 250 ms */
+#define SIXP_PERSIST 50 /* in 256ths */
+#define SIXP_SLOTTIME 10 /* 100 ms */
+#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;
+ spinlock_t rxlock;
+
+ 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;
+ refcount_t refcnt;
+ struct completion dead;
+ spinlock_t lock;
+};
+
+#define AX25_6PACK_HEADER_LEN 0
+
+static void sixpack_decode(struct sixpack *, const 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(struct timer_list *t)
+{
+ struct sixpack *sp = from_timer(sp, t, tx_t);
+ 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 (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(&sp->tx_t);
+ }
+
+ 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);
+
+ if (skb->protocol == htons(ETH_P_IP))
+ return ax25_ip_xmit(skb);
+
+ 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;
+}
+
+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);
+ __dev_addr_set(dev, &sa->sax25_call, AX25_ADDR_LEN);
+ netif_addr_unlock(dev);
+ netif_tx_unlock_bh(dev);
+
+ return 0;
+}
+
+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->mtu = SIXP_MTU;
+ dev->hard_header_len = AX25_MAX_HEADER_LEN;
+ dev->header_ops = &ax25_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);
+ dev_addr_set(dev, (u8 *)&ax25_defaddr);
+
+ 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 + 1)) == NULL)
+ goto out_mem;
+
+ ptr = skb_put(skb, count + 1);
+ *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)
+ refcount_inc(&sp->refcnt);
+ read_unlock(&disc_data_lock);
+
+ return sp;
+}
+
+static void sp_put(struct sixpack *sp)
+{
+ if (refcount_dec_and_test(&sp->refcnt))
+ complete(&sp->dead);
+}
+
+/*
+ * 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 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 u8 *cp,
+ const u8 *fp, size_t count)
+{
+ struct sixpack *sp;
+ int count1;
+
+ if (!count)
+ return;
+
+ sp = sp_get(tty);
+ if (!sp)
+ return;
+
+ /* 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, cp, 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(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);
+ spin_lock_init(&sp->rxlock);
+ 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);
+
+ unregister_netdev(sp->dev);
+
+ del_timer_sync(&sp->tx_t);
+ del_timer_sync(&sp->resync_t);
+
+ /* Free all 6pack frame buffers after unreg. */
+ kfree(sp->rbuff);
+ kfree(sp->xbuff);
+
+ free_netdev(sp->dev);
+}
+
+/* Perform I/O control on an active 6pack channel. */
+static int sixpack_ioctl(struct tty_struct *tty, 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);
+ __dev_addr_set(dev, &addr, AX25_ADDR_LEN);
+ netif_tx_unlock_bh(dev);
+ err = 0;
+ break;
+ }
+ default:
+ err = tty_mode_ioctl(tty, 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);
+ spin_lock_bh(&sp->rxlock);
+ 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;
+ spin_unlock_bh(&sp->rxlock);
+ }
+ 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) {
+ spin_lock_bh(&sp->rxlock);
+ decode_data(sp, inbyte);
+ spin_unlock_bh(&sp->rxlock);
+ }
+ }
+}
+
+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);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-06 01:03:43 +0000