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linux/drivers/net/hamradio/6pack.c
Alan Cox 33f0f88f1c [PATCH] TTY layer buffering revamp 
The API and code have been through various bits of initial review by
serial driver people but they definitely need to live somewhere for a
while so the unconverted drivers can get knocked into shape, existing
drivers that have been updated can be better tuned and bugs whacked out.

This replaces the tty flip buffers with kmalloc objects in rings. In the
normal situation for an IRQ driven serial port at typical speeds the
behaviour is pretty much the same, two buffers end up allocated and the
kernel cycles between them as before.

When there are delays or at high speed we now behave far better as the
buffer pool can grow a bit rather than lose characters. This also means
that we can operate at higher speeds reliably.

For drivers that receive characters in blocks (DMA based, USB and
especially virtualisation) the layer allows a lot of driver specific
code that works around the tty layer with private secondary queues to be
removed. The IBM folks need this sort of layer, the smart serial port
people do, the virtualisers do (because a virtualised tty typically
operates at infinite speed rather than emulating 9600 baud).

Finally many drivers had invalid and unsafe attempts to avoid buffer
overflows by directly invoking tty methods extracted out of the innards
of work queue structs. These are no longer needed and all go away. That
fixes various random hangs with serial ports on overflow.

The other change in here is to optimise the receive_room path that is
used by some callers. It turns out that only one ldisc uses receive room
except asa constant and it updates it far far less than the value is
read. We thus make it a variable not a function call.

I expect the code to contain bugs due to the size alone but I'll be
watching and squashing them and feeding out new patches as it goes.

Because the buffers now dynamically expand you should only run out of
buffering when the kernel runs out of memory for real.  That means a lot of
the horrible hacks high performance drivers used to do just aren't needed any
more.

Description:

tty_insert_flip_char is an old API and continues to work as before, as does
tty_flip_buffer_push() [this is why many drivers dont need modification].  It
does now also return the number of chars inserted

There are also

tty_buffer_request_room(tty, len)

which asks for a buffer block of the length requested and returns the space
found.  This improves efficiency with hardware that knows how much to
transfer.

and tty_insert_flip_string_flags(tty, str, flags, len)

to insert a string of characters and flags

For a smart interface the usual code is

    len = tty_request_buffer_room(tty, amount_hardware_says);
    tty_insert_flip_string(tty, buffer_from_card, len);

More description!

At the moment tty buffers are attached directly to the tty.  This is causing a
lot of the problems related to tty layer locking, also problems at high speed
and also with bursty data (such as occurs in virtualised environments)

I'm working on ripping out the flip buffers and replacing them with a pool of
dynamically allocated buffers.  This allows both for old style "byte I/O"
devices and also helps virtualisation and smart devices where large blocks of
data suddenely materialise and need storing.

So far so good.  Lots of drivers reference tty->flip.*.  Several of them also
call directly and unsafely into function pointers it provides.  This will all
break.  Most drivers can use tty_insert_flip_char which can be kept as an API
but others need more.

At the moment I've added the following interfaces, if people think more will
be needed now is a good time to say

 int tty_buffer_request_room(tty, size)

Try and ensure at least size bytes are available, returns actual room (may be
zero).  At the moment it just uses the flipbuf space but that will change.
Repeated calls without characters being added are not cumulative.  (ie if you
call it with 1, 1, 1, and then 4 you'll have four characters of space.  The
other functions will also try and grow buffers in future but this will be a
more efficient way when you know block sizes.

 int tty_insert_flip_char(tty, ch, flag)

As before insert a character if there is room.  Now returns 1 for success, 0
for failure.

 int tty_insert_flip_string(tty, str, len)

Insert a block of non error characters.  Returns the number inserted.

 int tty_prepare_flip_string(tty, strptr, len)

Adjust the buffer to allow len characters to be added.  Returns a buffer
pointer in strptr and the length available.  This allows for hardware that
needs to use functions like insl or mencpy_fromio.

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 08:01:59 -08:00

1030 lines
25 KiB
C
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/*
* 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/config.h>
#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 <asm/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->driver->write(sp->tty, &sp->led_state, 1);
sp->tx_enable = 1;
actual = sp->tty->driver->write(sp->tty, sp->xbuff, sp->status2);
sp->xleft -= actual;
sp->xhead += actual;
sp->led_state = 0x60;
sp->tty->driver->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->driver->write(sp->tty, &sp->led_state, 1);
sp->tx_enable = 1;
actual = sp->tty->driver->write(sp->tty, sp->xbuff, count);
sp->xleft = count - actual;
sp->xhead = sp->xbuff + actual;
sp->led_state = 0x60;
sp->tty->driver->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->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 int 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);
sp->stats.tx_bytes += skb->len;
sp_encaps(sp, skb->data, skb->len);
spin_unlock_bh(&sp->lock);
dev_kfree_skb(skb);
return 0;
}
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, void *daddr, void *saddr, unsigned len)
{
#ifdef CONFIG_INET
if (type != htons(ETH_P_AX25))
return ax25_hard_header(skb, dev, type, daddr, saddr, len);
#endif
return 0;
}
static struct net_device_stats *sp_get_stats(struct net_device *dev)
{
struct sixpack *sp = netdev_priv(dev);
return &sp->stats;
}
static int sp_set_mac_address(struct net_device *dev, void *addr)
{
struct sockaddr_ax25 *sa = addr;
spin_lock_irq(&dev->xmit_lock);
memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
spin_unlock_irq(&dev->xmit_lock);
return 0;
}
static int sp_rebuild_header(struct sk_buff *skb)
{
#ifdef CONFIG_INET
return ax25_rebuild_header(skb);
#else
return 0;
#endif
}
static void sp_setup(struct net_device *dev)
{
static char ax25_bcast[AX25_ADDR_LEN] =
{'Q'<<1,'S'<<1,'T'<<1,' '<<1,' '<<1,' '<<1,'0'<<1};
static char ax25_test[AX25_ADDR_LEN] =
{'L'<<1,'I'<<1,'N'<<1,'U'<<1,'X'<<1,' '<<1,'1'<<1};
/* Finish setting up the DEVICE info. */
dev->mtu = SIXP_MTU;
dev->hard_start_xmit = sp_xmit;
dev->open = sp_open_dev;
dev->destructor = free_netdev;
dev->stop = sp_close;
dev->hard_header = sp_header;
dev->get_stats = sp_get_stats;
dev->set_mac_address = sp_set_mac_address;
dev->hard_header_len = AX25_MAX_HEADER_LEN;
dev->addr_len = AX25_ADDR_LEN;
dev->type = ARPHRD_AX25;
dev->tx_queue_len = 10;
dev->rebuild_header = sp_rebuild_header;
dev->tx_timeout = NULL;
/* Only activated in AX.25 mode */
memcpy(dev->broadcast, ax25_bcast, AX25_ADDR_LEN);
memcpy(dev->dev_addr, ax25_test, AX25_ADDR_LEN);
SET_MODULE_OWNER(dev);
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->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->last_rx = jiffies;
sp->stats.rx_packets++;
return;
out_mem:
sp->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->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->driver->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->stats.rx_errors++;
continue;
}
}
sixpack_decode(sp, buf, count1);
sp_put(sp);
if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
&& tty->driver->unthrottle)
tty->driver->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->driver->write(sp->tty, &sp->led_state, 1);
sp->tty->driver->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->driver->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;
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);
init_MUTEX_LOCKED(&sp->dead_sem);
/* !!! 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(&disc_data_lock);
sp = tty->disc_data;
tty->disc_data = NULL;
write_unlock(&disc_data_lock);
if (sp == 0)
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 = sp->dev;
unsigned int tmp, err;
if (!sp)
return -ENXIO;
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;
}
spin_lock_irq(&dev->xmit_lock);
memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
spin_unlock_irq(&dev->xmit_lock);
err = 0;
break;
}
/* Allow stty to read, but not set, the serial port */
case TCGETS:
case TCGETA:
err = n_tty_ioctl(tty, (struct file *) file, cmd, arg);
break;
default:
err = -ENOIOCTLCMD;
}
sp_put(sp);
return err;
}
static struct tty_ldisc sp_ldisc = {
.owner = THIS_MODULE,
.magic = TTY_LDISC_MAGIC,
.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 char msg_banner[] __initdata = KERN_INFO \
"AX.25: 6pack driver, " SIXPACK_VERSION "\n";
static 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->driver->write(sp->tty, &sp->led_state, 1);
sp->tx_enable = 1;
actual = sp->tty->driver->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->driver->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->driver->write(sp->tty, &sp->led_state, 1);
}
} else {
sp->led_state = 0x60;
/* fill trailing bytes with zeroes */
sp->tty->driver->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);
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