2 * PPP async serial channel driver for Linux.
4 * Copyright 1999 Paul Mackerras.
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
11 * This driver provides the encapsulation and framing for sending
12 * and receiving PPP frames over async serial lines. It relies on
13 * the generic PPP layer to give it frames to send and to process
14 * received frames. It implements the PPP line discipline.
16 * Part of the code in this driver was inspired by the old async-only
17 * PPP driver, written by Michael Callahan and Al Longyear, and
18 * subsequently hacked by Paul Mackerras.
21 #include <linux/module.h>
22 #include <linux/kernel.h>
23 #include <linux/skbuff.h>
24 #include <linux/tty.h>
25 #include <linux/netdevice.h>
26 #include <linux/poll.h>
27 #include <linux/crc-ccitt.h>
28 #include <linux/ppp_defs.h>
29 #include <linux/if_ppp.h>
30 #include <linux/ppp_channel.h>
31 #include <linux/spinlock.h>
32 #include <linux/init.h>
33 #include <linux/jiffies.h>
34 #include <asm/uaccess.h>
35 #include <asm/string.h>
37 #define PPP_VERSION "2.4.2"
41 /* Structure for storing local state. */
43 struct tty_struct
*tty
;
50 unsigned long xmit_flags
;
53 unsigned int bytes_sent
;
54 unsigned int bytes_rcvd
;
61 unsigned long last_xmit
;
65 struct sk_buff_head rqueue
;
67 struct tasklet_struct tsk
;
70 struct semaphore dead_sem
;
71 struct ppp_channel chan
; /* interface to generic ppp layer */
72 unsigned char obuf
[OBUFSIZE
];
75 /* Bit numbers in xmit_flags */
83 #define SC_PREV_ERROR 4
86 #define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
88 static int flag_time
= HZ
;
89 module_param(flag_time
, int, 0);
90 MODULE_PARM_DESC(flag_time
, "ppp_async: interval between flagged packets (in clock ticks)");
91 MODULE_LICENSE("GPL");
92 MODULE_ALIAS_LDISC(N_PPP
);
97 static int ppp_async_encode(struct asyncppp
*ap
);
98 static int ppp_async_send(struct ppp_channel
*chan
, struct sk_buff
*skb
);
99 static int ppp_async_push(struct asyncppp
*ap
);
100 static void ppp_async_flush_output(struct asyncppp
*ap
);
101 static void ppp_async_input(struct asyncppp
*ap
, const unsigned char *buf
,
102 char *flags
, int count
);
103 static int ppp_async_ioctl(struct ppp_channel
*chan
, unsigned int cmd
,
105 static void ppp_async_process(unsigned long arg
);
107 static void async_lcp_peek(struct asyncppp
*ap
, unsigned char *data
,
108 int len
, int inbound
);
110 static struct ppp_channel_ops async_ops
= {
116 * Routines implementing the PPP line discipline.
120 * We have a potential race on dereferencing tty->disc_data,
121 * because the tty layer provides no locking at all - thus one
122 * cpu could be running ppp_asynctty_receive while another
123 * calls ppp_asynctty_close, which zeroes tty->disc_data and
124 * frees the memory that ppp_asynctty_receive is using. The best
125 * way to fix this is to use a rwlock in the tty struct, but for now
126 * we use a single global rwlock for all ttys in ppp line discipline.
128 * FIXME: this is no longer true. The _close path for the ldisc is
129 * now guaranteed to be sane.
131 static DEFINE_RWLOCK(disc_data_lock
);
133 static struct asyncppp
*ap_get(struct tty_struct
*tty
)
138 read_lock_irqsave(&disc_data_lock
, flags
);
141 atomic_inc(&ap
->refcnt
);
142 read_unlock_irqrestore(&disc_data_lock
, flags
);
147 static void ap_put(struct asyncppp
*ap
)
149 if (atomic_dec_and_test(&ap
->refcnt
))
154 * Called when a tty is put into PPP line discipline. Called in process
158 ppp_asynctty_open(struct tty_struct
*tty
)
164 if (tty
->ops
->write
== NULL
)
168 ap
= kzalloc(sizeof(*ap
), GFP_KERNEL
);
172 /* initialize the asyncppp structure */
175 spin_lock_init(&ap
->xmit_lock
);
176 spin_lock_init(&ap
->recv_lock
);
178 ap
->xaccm
[3] = 0x60000000U
;
184 skb_queue_head_init(&ap
->rqueue
);
185 tasklet_init(&ap
->tsk
, ppp_async_process
, (unsigned long) ap
);
187 atomic_set(&ap
->refcnt
, 1);
188 init_MUTEX_LOCKED(&ap
->dead_sem
);
190 ap
->chan
.private = ap
;
191 ap
->chan
.ops
= &async_ops
;
192 ap
->chan
.mtu
= PPP_MRU
;
193 speed
= tty_get_baud_rate(tty
);
194 ap
->chan
.speed
= speed
;
195 err
= ppp_register_channel(&ap
->chan
);
200 tty
->receive_room
= 65536;
210 * Called when the tty is put into another line discipline
211 * or it hangs up. We have to wait for any cpu currently
212 * executing in any of the other ppp_asynctty_* routines to
213 * finish before we can call ppp_unregister_channel and free
214 * the asyncppp struct. This routine must be called from
215 * process context, not interrupt or softirq context.
218 ppp_asynctty_close(struct tty_struct
*tty
)
223 write_lock_irqsave(&disc_data_lock
, flags
);
225 tty
->disc_data
= NULL
;
226 write_unlock_irqrestore(&disc_data_lock
, flags
);
231 * We have now ensured that nobody can start using ap from now
232 * on, but we have to wait for all existing users to finish.
233 * Note that ppp_unregister_channel ensures that no calls to
234 * our channel ops (i.e. ppp_async_send/ioctl) are in progress
235 * by the time it returns.
237 if (!atomic_dec_and_test(&ap
->refcnt
))
239 tasklet_kill(&ap
->tsk
);
241 ppp_unregister_channel(&ap
->chan
);
243 skb_queue_purge(&ap
->rqueue
);
249 * Called on tty hangup in process context.
251 * Wait for I/O to driver to complete and unregister PPP channel.
252 * This is already done by the close routine, so just call that.
254 static int ppp_asynctty_hangup(struct tty_struct
*tty
)
256 ppp_asynctty_close(tty
);
261 * Read does nothing - no data is ever available this way.
262 * Pppd reads and writes packets via /dev/ppp instead.
265 ppp_asynctty_read(struct tty_struct
*tty
, struct file
*file
,
266 unsigned char __user
*buf
, size_t count
)
272 * Write on the tty does nothing, the packets all come in
273 * from the ppp generic stuff.
276 ppp_asynctty_write(struct tty_struct
*tty
, struct file
*file
,
277 const unsigned char *buf
, size_t count
)
283 * Called in process context only. May be re-entered by multiple
284 * ioctl calling threads.
288 ppp_asynctty_ioctl(struct tty_struct
*tty
, struct file
*file
,
289 unsigned int cmd
, unsigned long arg
)
291 struct asyncppp
*ap
= ap_get(tty
);
293 int __user
*p
= (int __user
*)arg
;
301 if (put_user(ppp_channel_index(&ap
->chan
), p
))
308 if (put_user(ppp_unit_number(&ap
->chan
), p
))
314 /* flush our buffers and the serial port's buffer */
315 if (arg
== TCIOFLUSH
|| arg
== TCOFLUSH
)
316 ppp_async_flush_output(ap
);
317 err
= tty_perform_flush(tty
, arg
);
322 if (put_user(val
, p
))
328 /* Try the various mode ioctls */
329 err
= tty_mode_ioctl(tty
, file
, cmd
, arg
);
336 /* No kernel lock - fine */
338 ppp_asynctty_poll(struct tty_struct
*tty
, struct file
*file
, poll_table
*wait
)
344 * This can now be called from hard interrupt level as well
345 * as soft interrupt level or mainline.
348 ppp_asynctty_receive(struct tty_struct
*tty
, const unsigned char *buf
,
349 char *cflags
, int count
)
351 struct asyncppp
*ap
= ap_get(tty
);
356 spin_lock_irqsave(&ap
->recv_lock
, flags
);
357 ppp_async_input(ap
, buf
, cflags
, count
);
358 spin_unlock_irqrestore(&ap
->recv_lock
, flags
);
359 if (!skb_queue_empty(&ap
->rqueue
))
360 tasklet_schedule(&ap
->tsk
);
365 ppp_asynctty_wakeup(struct tty_struct
*tty
)
367 struct asyncppp
*ap
= ap_get(tty
);
369 clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
372 set_bit(XMIT_WAKEUP
, &ap
->xmit_flags
);
373 tasklet_schedule(&ap
->tsk
);
378 static struct tty_ldisc_ops ppp_ldisc
= {
379 .owner
= THIS_MODULE
,
380 .magic
= TTY_LDISC_MAGIC
,
382 .open
= ppp_asynctty_open
,
383 .close
= ppp_asynctty_close
,
384 .hangup
= ppp_asynctty_hangup
,
385 .read
= ppp_asynctty_read
,
386 .write
= ppp_asynctty_write
,
387 .ioctl
= ppp_asynctty_ioctl
,
388 .poll
= ppp_asynctty_poll
,
389 .receive_buf
= ppp_asynctty_receive
,
390 .write_wakeup
= ppp_asynctty_wakeup
,
398 err
= tty_register_ldisc(N_PPP
, &ppp_ldisc
);
400 printk(KERN_ERR
"PPP_async: error %d registering line disc.\n",
406 * The following routines provide the PPP channel interface.
409 ppp_async_ioctl(struct ppp_channel
*chan
, unsigned int cmd
, unsigned long arg
)
411 struct asyncppp
*ap
= chan
->private;
412 void __user
*argp
= (void __user
*)arg
;
413 int __user
*p
= argp
;
420 val
= ap
->flags
| ap
->rbits
;
421 if (put_user(val
, p
))
426 if (get_user(val
, p
))
428 ap
->flags
= val
& ~SC_RCV_BITS
;
429 spin_lock_irq(&ap
->recv_lock
);
430 ap
->rbits
= val
& SC_RCV_BITS
;
431 spin_unlock_irq(&ap
->recv_lock
);
435 case PPPIOCGASYNCMAP
:
436 if (put_user(ap
->xaccm
[0], (u32 __user
*)argp
))
440 case PPPIOCSASYNCMAP
:
441 if (get_user(ap
->xaccm
[0], (u32 __user
*)argp
))
446 case PPPIOCGRASYNCMAP
:
447 if (put_user(ap
->raccm
, (u32 __user
*)argp
))
451 case PPPIOCSRASYNCMAP
:
452 if (get_user(ap
->raccm
, (u32 __user
*)argp
))
457 case PPPIOCGXASYNCMAP
:
458 if (copy_to_user(argp
, ap
->xaccm
, sizeof(ap
->xaccm
)))
462 case PPPIOCSXASYNCMAP
:
463 if (copy_from_user(accm
, argp
, sizeof(accm
)))
465 accm
[2] &= ~0x40000000U
; /* can't escape 0x5e */
466 accm
[3] |= 0x60000000U
; /* must escape 0x7d, 0x7e */
467 memcpy(ap
->xaccm
, accm
, sizeof(ap
->xaccm
));
472 if (put_user(ap
->mru
, p
))
477 if (get_user(val
, p
))
493 * This is called at softirq level to deliver received packets
494 * to the ppp_generic code, and to tell the ppp_generic code
495 * if we can accept more output now.
497 static void ppp_async_process(unsigned long arg
)
499 struct asyncppp
*ap
= (struct asyncppp
*) arg
;
502 /* process received packets */
503 while ((skb
= skb_dequeue(&ap
->rqueue
)) != NULL
) {
505 ppp_input_error(&ap
->chan
, 0);
506 ppp_input(&ap
->chan
, skb
);
509 /* try to push more stuff out */
510 if (test_bit(XMIT_WAKEUP
, &ap
->xmit_flags
) && ppp_async_push(ap
))
511 ppp_output_wakeup(&ap
->chan
);
515 * Procedures for encapsulation and framing.
519 * Procedure to encode the data for async serial transmission.
520 * Does octet stuffing (escaping), puts the address/control bytes
521 * on if A/C compression is disabled, and does protocol compression.
522 * Assumes ap->tpkt != 0 on entry.
523 * Returns 1 if we finished the current frame, 0 otherwise.
526 #define PUT_BYTE(ap, buf, c, islcp) do { \
527 if ((islcp && c < 0x20) || (ap->xaccm[c >> 5] & (1 << (c & 0x1f)))) {\
528 *buf++ = PPP_ESCAPE; \
535 ppp_async_encode(struct asyncppp
*ap
)
537 int fcs
, i
, count
, c
, proto
;
538 unsigned char *buf
, *buflim
;
546 data
= ap
->tpkt
->data
;
547 count
= ap
->tpkt
->len
;
549 proto
= (data
[0] << 8) + data
[1];
552 * LCP packets with code values between 1 (configure-reqest)
553 * and 7 (code-reject) must be sent as though no options
554 * had been negotiated.
556 islcp
= proto
== PPP_LCP
&& 1 <= data
[2] && data
[2] <= 7;
560 async_lcp_peek(ap
, data
, count
, 0);
563 * Start of a new packet - insert the leading FLAG
564 * character if necessary.
566 if (islcp
|| flag_time
== 0
567 || time_after_eq(jiffies
, ap
->last_xmit
+ flag_time
))
569 ap
->last_xmit
= jiffies
;
573 * Put in the address/control bytes if necessary
575 if ((ap
->flags
& SC_COMP_AC
) == 0 || islcp
) {
576 PUT_BYTE(ap
, buf
, 0xff, islcp
);
577 fcs
= PPP_FCS(fcs
, 0xff);
578 PUT_BYTE(ap
, buf
, 0x03, islcp
);
579 fcs
= PPP_FCS(fcs
, 0x03);
584 * Once we put in the last byte, we need to put in the FCS
585 * and closing flag, so make sure there is at least 7 bytes
586 * of free space in the output buffer.
588 buflim
= ap
->obuf
+ OBUFSIZE
- 6;
589 while (i
< count
&& buf
< buflim
) {
591 if (i
== 1 && c
== 0 && (ap
->flags
& SC_COMP_PROT
))
592 continue; /* compress protocol field */
593 fcs
= PPP_FCS(fcs
, c
);
594 PUT_BYTE(ap
, buf
, c
, islcp
);
599 * Remember where we are up to in this packet.
608 * We have finished the packet. Add the FCS and flag.
612 PUT_BYTE(ap
, buf
, c
, islcp
);
613 c
= (fcs
>> 8) & 0xff;
614 PUT_BYTE(ap
, buf
, c
, islcp
);
624 * Transmit-side routines.
628 * Send a packet to the peer over an async tty line.
629 * Returns 1 iff the packet was accepted.
630 * If the packet was not accepted, we will call ppp_output_wakeup
631 * at some later time.
634 ppp_async_send(struct ppp_channel
*chan
, struct sk_buff
*skb
)
636 struct asyncppp
*ap
= chan
->private;
640 if (test_and_set_bit(XMIT_FULL
, &ap
->xmit_flags
))
641 return 0; /* already full */
650 * Push as much data as possible out to the tty.
653 ppp_async_push(struct asyncppp
*ap
)
655 int avail
, sent
, done
= 0;
656 struct tty_struct
*tty
= ap
->tty
;
660 * We can get called recursively here if the tty write
661 * function calls our wakeup function. This can happen
662 * for example on a pty with both the master and slave
663 * set to PPP line discipline.
664 * We use the XMIT_BUSY bit to detect this and get out,
665 * leaving the XMIT_WAKEUP bit set to tell the other
666 * instance that it may now be able to write more now.
668 if (test_and_set_bit(XMIT_BUSY
, &ap
->xmit_flags
))
670 spin_lock_bh(&ap
->xmit_lock
);
672 if (test_and_clear_bit(XMIT_WAKEUP
, &ap
->xmit_flags
))
674 if (!tty_stuffed
&& ap
->optr
< ap
->olim
) {
675 avail
= ap
->olim
- ap
->optr
;
676 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
677 sent
= tty
->ops
->write(tty
, ap
->optr
, avail
);
679 goto flush
; /* error, e.g. loss of CD */
685 if (ap
->optr
>= ap
->olim
&& ap
->tpkt
) {
686 if (ppp_async_encode(ap
)) {
687 /* finished processing ap->tpkt */
688 clear_bit(XMIT_FULL
, &ap
->xmit_flags
);
694 * We haven't made any progress this time around.
695 * Clear XMIT_BUSY to let other callers in, but
696 * after doing so we have to check if anyone set
697 * XMIT_WAKEUP since we last checked it. If they
698 * did, we should try again to set XMIT_BUSY and go
699 * around again in case XMIT_BUSY was still set when
700 * the other caller tried.
702 clear_bit(XMIT_BUSY
, &ap
->xmit_flags
);
703 /* any more work to do? if not, exit the loop */
704 if (!(test_bit(XMIT_WAKEUP
, &ap
->xmit_flags
)
705 || (!tty_stuffed
&& ap
->tpkt
)))
707 /* more work to do, see if we can do it now */
708 if (test_and_set_bit(XMIT_BUSY
, &ap
->xmit_flags
))
711 spin_unlock_bh(&ap
->xmit_lock
);
715 clear_bit(XMIT_BUSY
, &ap
->xmit_flags
);
719 clear_bit(XMIT_FULL
, &ap
->xmit_flags
);
723 spin_unlock_bh(&ap
->xmit_lock
);
728 * Flush output from our internal buffers.
729 * Called for the TCFLSH ioctl. Can be entered in parallel
730 * but this is covered by the xmit_lock.
733 ppp_async_flush_output(struct asyncppp
*ap
)
737 spin_lock_bh(&ap
->xmit_lock
);
739 if (ap
->tpkt
!= NULL
) {
742 clear_bit(XMIT_FULL
, &ap
->xmit_flags
);
745 spin_unlock_bh(&ap
->xmit_lock
);
747 ppp_output_wakeup(&ap
->chan
);
751 * Receive-side routines.
754 /* see how many ordinary chars there are at the start of buf */
756 scan_ordinary(struct asyncppp
*ap
, const unsigned char *buf
, int count
)
760 for (i
= 0; i
< count
; ++i
) {
762 if (c
== PPP_ESCAPE
|| c
== PPP_FLAG
763 || (c
< 0x20 && (ap
->raccm
& (1 << c
)) != 0))
769 /* called when a flag is seen - do end-of-packet processing */
771 process_input_packet(struct asyncppp
*ap
)
775 unsigned int len
, fcs
, proto
;
778 if (ap
->state
& (SC_TOSS
| SC_ESCAPE
))
782 return; /* 0-length packet */
788 goto err
; /* too short */
790 for (; len
> 0; --len
)
791 fcs
= PPP_FCS(fcs
, *p
++);
792 if (fcs
!= PPP_GOODFCS
)
793 goto err
; /* bad FCS */
794 skb_trim(skb
, skb
->len
- 2);
796 /* check for address/control and protocol compression */
798 if (p
[0] == PPP_ALLSTATIONS
) {
799 /* chop off address/control */
800 if (p
[1] != PPP_UI
|| skb
->len
< 3)
802 p
= skb_pull(skb
, 2);
806 /* protocol is compressed */
807 skb_push(skb
, 1)[0] = 0;
811 proto
= (proto
<< 8) + p
[1];
812 if (proto
== PPP_LCP
)
813 async_lcp_peek(ap
, p
, skb
->len
, 1);
816 /* queue the frame to be processed */
817 skb
->cb
[0] = ap
->state
;
818 skb_queue_tail(&ap
->rqueue
, skb
);
824 /* frame had an error, remember that, reset SC_TOSS & SC_ESCAPE */
825 ap
->state
= SC_PREV_ERROR
;
827 /* make skb appear as freshly allocated */
829 skb_reserve(skb
, - skb_headroom(skb
));
833 /* Called when the tty driver has data for us. Runs parallel with the
834 other ldisc functions but will not be re-entered */
837 ppp_async_input(struct asyncppp
*ap
, const unsigned char *buf
,
838 char *flags
, int count
)
841 int c
, i
, j
, n
, s
, f
;
844 /* update bits used for 8-bit cleanness detection */
845 if (~ap
->rbits
& SC_RCV_BITS
) {
847 for (i
= 0; i
< count
; ++i
) {
849 if (flags
&& flags
[i
] != 0)
851 s
|= (c
& 0x80)? SC_RCV_B7_1
: SC_RCV_B7_0
;
852 c
= ((c
>> 4) ^ c
) & 0xf;
853 s
|= (0x6996 & (1 << c
))? SC_RCV_ODDP
: SC_RCV_EVNP
;
859 /* scan through and see how many chars we can do in bulk */
860 if ((ap
->state
& SC_ESCAPE
) && buf
[0] == PPP_ESCAPE
)
863 n
= scan_ordinary(ap
, buf
, count
);
866 if (flags
&& (ap
->state
& SC_TOSS
) == 0) {
867 /* check the flags to see if any char had an error */
868 for (j
= 0; j
< n
; ++j
)
869 if ((f
= flags
[j
]) != 0)
874 ap
->state
|= SC_TOSS
;
876 } else if (n
> 0 && (ap
->state
& SC_TOSS
) == 0) {
877 /* stuff the chars in the skb */
880 skb
= dev_alloc_skb(ap
->mru
+ PPP_HDRLEN
+ 2);
886 /* Try to get the payload 4-byte aligned.
887 * This should match the
888 * PPP_ALLSTATIONS/PPP_UI/compressed tests in
889 * process_input_packet, but we do not have
890 * enough chars here to test buf[1] and buf[2].
892 if (buf
[0] != PPP_ALLSTATIONS
)
893 skb_reserve(skb
, 2 + (buf
[0] & 1));
895 if (n
> skb_tailroom(skb
)) {
896 /* packet overflowed MRU */
897 ap
->state
|= SC_TOSS
;
899 sp
= skb_put(skb
, n
);
901 if (ap
->state
& SC_ESCAPE
) {
903 ap
->state
&= ~SC_ESCAPE
;
912 if (flags
!= NULL
&& flags
[n
] != 0) {
913 ap
->state
|= SC_TOSS
;
914 } else if (c
== PPP_FLAG
) {
915 process_input_packet(ap
);
916 } else if (c
== PPP_ESCAPE
) {
917 ap
->state
|= SC_ESCAPE
;
918 } else if (I_IXON(ap
->tty
)) {
919 if (c
== START_CHAR(ap
->tty
))
921 else if (c
== STOP_CHAR(ap
->tty
))
924 /* otherwise it's a char in the recv ACCM */
935 printk(KERN_ERR
"PPPasync: no memory (input pkt)\n");
936 ap
->state
|= SC_TOSS
;
940 * We look at LCP frames going past so that we can notice
941 * and react to the LCP configure-ack from the peer.
942 * In the situation where the peer has been sent a configure-ack
943 * already, LCP is up once it has sent its configure-ack
944 * so the immediately following packet can be sent with the
945 * configured LCP options. This allows us to process the following
946 * packet correctly without pppd needing to respond quickly.
948 * We only respond to the received configure-ack if we have just
949 * sent a configure-request, and the configure-ack contains the
950 * same data (this is checked using a 16-bit crc of the data).
952 #define CONFREQ 1 /* LCP code field values */
954 #define LCP_MRU 1 /* LCP option numbers */
955 #define LCP_ASYNCMAP 2
957 static void async_lcp_peek(struct asyncppp
*ap
, unsigned char *data
,
958 int len
, int inbound
)
960 int dlen
, fcs
, i
, code
;
963 data
+= 2; /* skip protocol bytes */
965 if (len
< 4) /* 4 = code, ID, length */
968 if (code
!= CONFACK
&& code
!= CONFREQ
)
970 dlen
= (data
[2] << 8) + data
[3];
972 return; /* packet got truncated or length is bogus */
974 if (code
== (inbound
? CONFACK
: CONFREQ
)) {
976 * sent confreq or received confack:
977 * calculate the crc of the data from the ID field on.
980 for (i
= 1; i
< dlen
; ++i
)
981 fcs
= PPP_FCS(fcs
, data
[i
]);
984 /* outbound confreq - remember the crc for later */
989 /* received confack, check the crc */
995 return; /* not interested in received confreq */
997 /* process the options in the confack */
1000 /* data[0] is code, data[1] is length */
1001 while (dlen
>= 2 && dlen
>= data
[1] && data
[1] >= 2) {
1004 val
= (data
[2] << 8) + data
[3];
1011 val
= (data
[2] << 24) + (data
[3] << 16)
1012 + (data
[4] << 8) + data
[5];
1024 static void __exit
ppp_async_cleanup(void)
1026 if (tty_unregister_ldisc(N_PPP
) != 0)
1027 printk(KERN_ERR
"failed to unregister PPP line discipline\n");
1030 module_init(ppp_async_init
);
1031 module_exit(ppp_async_cleanup
);