1 /* generic HDLC line discipline for Linux
3 * Written by Paul Fulghum paulkf@microgate.com
4 * for Microgate Corporation
6 * Microgate and SyncLink are registered trademarks of Microgate Corporation
8 * Adapted from ppp.c, written by Michael Callahan <callahan@maths.ox.ac.uk>,
9 * Al Longyear <longyear@netcom.com>,
10 * Paul Mackerras <Paul.Mackerras@cs.anu.edu.au>
12 * Original release 01/11/99
14 * This code is released under the GNU General Public License (GPL)
16 * This module implements the tty line discipline N_HDLC for use with
17 * tty device drivers that support bit-synchronous HDLC communications.
19 * All HDLC data is frame oriented which means:
21 * 1. tty write calls represent one complete transmit frame of data
22 * The device driver should accept the complete frame or none of
23 * the frame (busy) in the write method. Each write call should have
24 * a byte count in the range of 2-65535 bytes (2 is min HDLC frame
25 * with 1 addr byte and 1 ctrl byte). The max byte count of 65535
26 * should include any crc bytes required. For example, when using
27 * CCITT CRC32, 4 crc bytes are required, so the maximum size frame
28 * the application may transmit is limited to 65531 bytes. For CCITT
29 * CRC16, the maximum application frame size would be 65533.
32 * 2. receive callbacks from the device driver represents
33 * one received frame. The device driver should bypass
34 * the tty flip buffer and call the line discipline receive
35 * callback directly to avoid fragmenting or concatenating
36 * multiple frames into a single receive callback.
38 * The HDLC line discipline queues the receive frames in separate
39 * buffers so complete receive frames can be returned by the
42 * 3. tty read calls returns an entire frame of data or nothing.
44 * 4. all send and receive data is considered raw. No processing
45 * or translation is performed by the line discipline, regardless
48 * 5. When line discipline is queried for the amount of receive
49 * data available (FIOC), 0 is returned if no data available,
50 * otherwise the count of the next available frame is returned.
51 * (instead of the sum of all received frame counts).
53 * These conventions allow the standard tty programming interface
54 * to be used for synchronous HDLC applications when used with
55 * this line discipline (or another line discipline that is frame
56 * oriented such as N_PPP).
58 * The SyncLink driver (synclink.c) implements both asynchronous
59 * (using standard line discipline N_TTY) and synchronous HDLC
60 * (using N_HDLC) communications, with the latter using the above
63 * This implementation is very basic and does not maintain
64 * any statistics. The main point is to enforce the raw data
65 * and frame orientation of HDLC communications.
67 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
68 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
69 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
70 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
71 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
72 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
73 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
74 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
75 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
76 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
77 * OF THE POSSIBILITY OF SUCH DAMAGE.
80 #define HDLC_MAGIC 0x239e
82 #include <linux/module.h>
83 #include <linux/init.h>
84 #include <linux/kernel.h>
85 #include <linux/sched.h>
86 #include <linux/types.h>
87 #include <linux/fcntl.h>
88 #include <linux/interrupt.h>
89 #include <linux/ptrace.h>
92 #define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch))
94 #include <linux/poll.h>
96 #include <linux/ioctl.h>
97 #include <linux/slab.h>
98 #include <linux/tty.h>
99 #include <linux/errno.h>
100 #include <linux/smp_lock.h>
101 #include <linux/string.h> /* used in new tty drivers */
102 #include <linux/signal.h> /* used in new tty drivers */
103 #include <linux/if.h>
104 #include <linux/bitops.h>
106 #include <asm/system.h>
107 #include <asm/termios.h>
108 #include <asm/uaccess.h>
111 * Buffers for individual HDLC frames
113 #define MAX_HDLC_FRAME_SIZE 65535
114 #define DEFAULT_RX_BUF_COUNT 10
115 #define MAX_RX_BUF_COUNT 60
116 #define DEFAULT_TX_BUF_COUNT 3
119 struct n_hdlc_buf
*link
;
124 #define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe)
126 struct n_hdlc_buf_list
{
127 struct n_hdlc_buf
*head
;
128 struct n_hdlc_buf
*tail
;
136 struct tty_struct
*tty
;
137 struct tty_struct
*backup_tty
;
140 struct n_hdlc_buf
*tbuf
;
141 struct n_hdlc_buf_list tx_buf_list
;
142 struct n_hdlc_buf_list rx_buf_list
;
143 struct n_hdlc_buf_list tx_free_buf_list
;
144 struct n_hdlc_buf_list rx_free_buf_list
;
148 * HDLC buffer list manipulation functions
150 static void n_hdlc_buf_list_init(struct n_hdlc_buf_list
*list
);
151 static void n_hdlc_buf_put(struct n_hdlc_buf_list
*list
,
152 struct n_hdlc_buf
*buf
);
153 static struct n_hdlc_buf
*n_hdlc_buf_get(struct n_hdlc_buf_list
*list
);
155 /* Local functions */
157 static struct n_hdlc
*n_hdlc_alloc (void);
159 /* debug level can be set by insmod for debugging purposes */
160 #define DEBUG_LEVEL_INFO 1
161 static int debuglevel
;
163 /* max frame size for memory allocations */
164 static int maxframe
= 4096;
168 static ssize_t
n_hdlc_tty_read(struct tty_struct
*tty
, struct file
*file
,
169 __u8 __user
*buf
, size_t nr
);
170 static ssize_t
n_hdlc_tty_write(struct tty_struct
*tty
, struct file
*file
,
171 const unsigned char *buf
, size_t nr
);
172 static int n_hdlc_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
173 unsigned int cmd
, unsigned long arg
);
174 static unsigned int n_hdlc_tty_poll(struct tty_struct
*tty
, struct file
*filp
,
176 static int n_hdlc_tty_open(struct tty_struct
*tty
);
177 static void n_hdlc_tty_close(struct tty_struct
*tty
);
178 static void n_hdlc_tty_receive(struct tty_struct
*tty
, const __u8
*cp
,
179 char *fp
, int count
);
180 static void n_hdlc_tty_wakeup(struct tty_struct
*tty
);
182 #define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f)))
184 #define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data))
185 #define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty)
187 static void flush_rx_queue(struct tty_struct
*tty
)
189 struct n_hdlc
*n_hdlc
= tty2n_hdlc(tty
);
190 struct n_hdlc_buf
*buf
;
192 while ((buf
= n_hdlc_buf_get(&n_hdlc
->rx_buf_list
)))
193 n_hdlc_buf_put(&n_hdlc
->rx_free_buf_list
, buf
);
196 static void flush_tx_queue(struct tty_struct
*tty
)
198 struct n_hdlc
*n_hdlc
= tty2n_hdlc(tty
);
199 struct n_hdlc_buf
*buf
;
202 while ((buf
= n_hdlc_buf_get(&n_hdlc
->tx_buf_list
)))
203 n_hdlc_buf_put(&n_hdlc
->tx_free_buf_list
, buf
);
204 spin_lock_irqsave(&n_hdlc
->tx_buf_list
.spinlock
, flags
);
206 n_hdlc_buf_put(&n_hdlc
->tx_free_buf_list
, n_hdlc
->tbuf
);
209 spin_unlock_irqrestore(&n_hdlc
->tx_buf_list
.spinlock
, flags
);
212 static struct tty_ldisc_ops n_hdlc_ldisc
= {
213 .owner
= THIS_MODULE
,
214 .magic
= TTY_LDISC_MAGIC
,
216 .open
= n_hdlc_tty_open
,
217 .close
= n_hdlc_tty_close
,
218 .read
= n_hdlc_tty_read
,
219 .write
= n_hdlc_tty_write
,
220 .ioctl
= n_hdlc_tty_ioctl
,
221 .poll
= n_hdlc_tty_poll
,
222 .receive_buf
= n_hdlc_tty_receive
,
223 .write_wakeup
= n_hdlc_tty_wakeup
,
224 .flush_buffer
= flush_rx_queue
,
228 * n_hdlc_release - release an n_hdlc per device line discipline info structure
229 * @n_hdlc - per device line discipline info structure
231 static void n_hdlc_release(struct n_hdlc
*n_hdlc
)
233 struct tty_struct
*tty
= n_hdlc2tty (n_hdlc
);
234 struct n_hdlc_buf
*buf
;
236 if (debuglevel
>= DEBUG_LEVEL_INFO
)
237 printk("%s(%d)n_hdlc_release() called\n",__FILE__
,__LINE__
);
239 /* Ensure that the n_hdlcd process is not hanging on select()/poll() */
240 wake_up_interruptible (&tty
->read_wait
);
241 wake_up_interruptible (&tty
->write_wait
);
243 if (tty
->disc_data
== n_hdlc
)
244 tty
->disc_data
= NULL
; /* Break the tty->n_hdlc link */
246 /* Release transmit and receive buffers */
248 buf
= n_hdlc_buf_get(&n_hdlc
->rx_free_buf_list
);
255 buf
= n_hdlc_buf_get(&n_hdlc
->tx_free_buf_list
);
262 buf
= n_hdlc_buf_get(&n_hdlc
->rx_buf_list
);
269 buf
= n_hdlc_buf_get(&n_hdlc
->tx_buf_list
);
278 } /* end of n_hdlc_release() */
281 * n_hdlc_tty_close - line discipline close
282 * @tty - pointer to tty info structure
284 * Called when the line discipline is changed to something
285 * else, the tty is closed, or the tty detects a hangup.
287 static void n_hdlc_tty_close(struct tty_struct
*tty
)
289 struct n_hdlc
*n_hdlc
= tty2n_hdlc (tty
);
291 if (debuglevel
>= DEBUG_LEVEL_INFO
)
292 printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__
,__LINE__
);
294 if (n_hdlc
!= NULL
) {
295 if (n_hdlc
->magic
!= HDLC_MAGIC
) {
296 printk (KERN_WARNING
"n_hdlc: trying to close unopened tty!\n");
299 #if defined(TTY_NO_WRITE_SPLIT)
300 clear_bit(TTY_NO_WRITE_SPLIT
,&tty
->flags
);
302 tty
->disc_data
= NULL
;
303 if (tty
== n_hdlc
->backup_tty
)
304 n_hdlc
->backup_tty
= NULL
;
305 if (tty
!= n_hdlc
->tty
)
307 if (n_hdlc
->backup_tty
) {
308 n_hdlc
->tty
= n_hdlc
->backup_tty
;
310 n_hdlc_release (n_hdlc
);
314 if (debuglevel
>= DEBUG_LEVEL_INFO
)
315 printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__
,__LINE__
);
317 } /* end of n_hdlc_tty_close() */
320 * n_hdlc_tty_open - called when line discipline changed to n_hdlc
321 * @tty - pointer to tty info structure
323 * Returns 0 if success, otherwise error code
325 static int n_hdlc_tty_open (struct tty_struct
*tty
)
327 struct n_hdlc
*n_hdlc
= tty2n_hdlc (tty
);
329 if (debuglevel
>= DEBUG_LEVEL_INFO
)
330 printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n",
334 /* There should not be an existing table for this slot. */
336 printk (KERN_ERR
"n_hdlc_tty_open:tty already associated!\n" );
340 n_hdlc
= n_hdlc_alloc();
342 printk (KERN_ERR
"n_hdlc_alloc failed\n");
346 tty
->disc_data
= n_hdlc
;
348 tty
->receive_room
= 65536;
350 #if defined(TTY_NO_WRITE_SPLIT)
351 /* change tty_io write() to not split large writes into 8K chunks */
352 set_bit(TTY_NO_WRITE_SPLIT
,&tty
->flags
);
355 /* flush receive data from driver */
356 tty_driver_flush_buffer(tty
);
358 if (debuglevel
>= DEBUG_LEVEL_INFO
)
359 printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__
,__LINE__
);
363 } /* end of n_tty_hdlc_open() */
366 * n_hdlc_send_frames - send frames on pending send buffer list
367 * @n_hdlc - pointer to ldisc instance data
368 * @tty - pointer to tty instance data
370 * Send frames on pending send buffer list until the driver does not accept a
371 * frame (busy) this function is called after adding a frame to the send buffer
372 * list and by the tty wakeup callback.
374 static void n_hdlc_send_frames(struct n_hdlc
*n_hdlc
, struct tty_struct
*tty
)
378 struct n_hdlc_buf
*tbuf
;
380 if (debuglevel
>= DEBUG_LEVEL_INFO
)
381 printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__
,__LINE__
);
384 spin_lock_irqsave(&n_hdlc
->tx_buf_list
.spinlock
, flags
);
387 spin_unlock_irqrestore(&n_hdlc
->tx_buf_list
.spinlock
, flags
);
392 spin_unlock_irqrestore(&n_hdlc
->tx_buf_list
.spinlock
, flags
);
394 /* get current transmit buffer or get new transmit */
395 /* buffer from list of pending transmit buffers */
399 tbuf
= n_hdlc_buf_get(&n_hdlc
->tx_buf_list
);
402 if (debuglevel
>= DEBUG_LEVEL_INFO
)
403 printk("%s(%d)sending frame %p, count=%d\n",
404 __FILE__
,__LINE__
,tbuf
,tbuf
->count
);
406 /* Send the next block of data to device */
407 tty
->flags
|= (1 << TTY_DO_WRITE_WAKEUP
);
408 actual
= tty
->ops
->write(tty
, tbuf
->buf
, tbuf
->count
);
410 /* rollback was possible and has been done */
411 if (actual
== -ERESTARTSYS
) {
415 /* if transmit error, throw frame away by */
416 /* pretending it was accepted by driver */
418 actual
= tbuf
->count
;
420 if (actual
== tbuf
->count
) {
421 if (debuglevel
>= DEBUG_LEVEL_INFO
)
422 printk("%s(%d)frame %p completed\n",
423 __FILE__
,__LINE__
,tbuf
);
425 /* free current transmit buffer */
426 n_hdlc_buf_put(&n_hdlc
->tx_free_buf_list
, tbuf
);
428 /* this tx buffer is done */
431 /* wait up sleeping writers */
432 wake_up_interruptible(&tty
->write_wait
);
434 /* get next pending transmit buffer */
435 tbuf
= n_hdlc_buf_get(&n_hdlc
->tx_buf_list
);
437 if (debuglevel
>= DEBUG_LEVEL_INFO
)
438 printk("%s(%d)frame %p pending\n",
439 __FILE__
,__LINE__
,tbuf
);
441 /* buffer not accepted by driver */
442 /* set this buffer as pending buffer */
449 tty
->flags
&= ~(1 << TTY_DO_WRITE_WAKEUP
);
451 /* Clear the re-entry flag */
452 spin_lock_irqsave(&n_hdlc
->tx_buf_list
.spinlock
, flags
);
454 spin_unlock_irqrestore(&n_hdlc
->tx_buf_list
.spinlock
, flags
);
459 if (debuglevel
>= DEBUG_LEVEL_INFO
)
460 printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__
,__LINE__
);
462 } /* end of n_hdlc_send_frames() */
465 * n_hdlc_tty_wakeup - Callback for transmit wakeup
466 * @tty - pointer to associated tty instance data
468 * Called when low level device driver can accept more send data.
470 static void n_hdlc_tty_wakeup(struct tty_struct
*tty
)
472 struct n_hdlc
*n_hdlc
= tty2n_hdlc(tty
);
474 if (debuglevel
>= DEBUG_LEVEL_INFO
)
475 printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__
,__LINE__
);
480 if (tty
!= n_hdlc
->tty
) {
481 tty
->flags
&= ~(1 << TTY_DO_WRITE_WAKEUP
);
485 n_hdlc_send_frames (n_hdlc
, tty
);
487 } /* end of n_hdlc_tty_wakeup() */
490 * n_hdlc_tty_receive - Called by tty driver when receive data is available
491 * @tty - pointer to tty instance data
492 * @data - pointer to received data
493 * @flags - pointer to flags for data
494 * @count - count of received data in bytes
496 * Called by tty low level driver when receive data is available. Data is
497 * interpreted as one HDLC frame.
499 static void n_hdlc_tty_receive(struct tty_struct
*tty
, const __u8
*data
,
500 char *flags
, int count
)
502 register struct n_hdlc
*n_hdlc
= tty2n_hdlc (tty
);
503 register struct n_hdlc_buf
*buf
;
505 if (debuglevel
>= DEBUG_LEVEL_INFO
)
506 printk("%s(%d)n_hdlc_tty_receive() called count=%d\n",
507 __FILE__
,__LINE__
, count
);
509 /* This can happen if stuff comes in on the backup tty */
510 if (!n_hdlc
|| tty
!= n_hdlc
->tty
)
513 /* verify line is using HDLC discipline */
514 if (n_hdlc
->magic
!= HDLC_MAGIC
) {
515 printk("%s(%d) line not using HDLC discipline\n",
520 if ( count
>maxframe
) {
521 if (debuglevel
>= DEBUG_LEVEL_INFO
)
522 printk("%s(%d) rx count>maxframesize, data discarded\n",
527 /* get a free HDLC buffer */
528 buf
= n_hdlc_buf_get(&n_hdlc
->rx_free_buf_list
);
530 /* no buffers in free list, attempt to allocate another rx buffer */
531 /* unless the maximum count has been reached */
532 if (n_hdlc
->rx_buf_list
.count
< MAX_RX_BUF_COUNT
)
533 buf
= kmalloc(N_HDLC_BUF_SIZE
, GFP_ATOMIC
);
537 if (debuglevel
>= DEBUG_LEVEL_INFO
)
538 printk("%s(%d) no more rx buffers, data discarded\n",
543 /* copy received data to HDLC buffer */
544 memcpy(buf
->buf
,data
,count
);
547 /* add HDLC buffer to list of received frames */
548 n_hdlc_buf_put(&n_hdlc
->rx_buf_list
, buf
);
550 /* wake up any blocked reads and perform async signalling */
551 wake_up_interruptible (&tty
->read_wait
);
552 if (n_hdlc
->tty
->fasync
!= NULL
)
553 kill_fasync (&n_hdlc
->tty
->fasync
, SIGIO
, POLL_IN
);
555 } /* end of n_hdlc_tty_receive() */
558 * n_hdlc_tty_read - Called to retrieve one frame of data (if available)
559 * @tty - pointer to tty instance data
560 * @file - pointer to open file object
561 * @buf - pointer to returned data buffer
562 * @nr - size of returned data buffer
564 * Returns the number of bytes returned or error code.
566 static ssize_t
n_hdlc_tty_read(struct tty_struct
*tty
, struct file
*file
,
567 __u8 __user
*buf
, size_t nr
)
569 struct n_hdlc
*n_hdlc
= tty2n_hdlc(tty
);
571 struct n_hdlc_buf
*rbuf
;
573 if (debuglevel
>= DEBUG_LEVEL_INFO
)
574 printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__
,__LINE__
);
576 /* Validate the pointers */
580 /* verify user access to buffer */
581 if (!access_ok(VERIFY_WRITE
, buf
, nr
)) {
582 printk(KERN_WARNING
"%s(%d) n_hdlc_tty_read() can't verify user "
583 "buffer\n", __FILE__
, __LINE__
);
590 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
595 n_hdlc
= tty2n_hdlc (tty
);
596 if (!n_hdlc
|| n_hdlc
->magic
!= HDLC_MAGIC
||
597 tty
!= n_hdlc
->tty
) {
602 rbuf
= n_hdlc_buf_get(&n_hdlc
->rx_buf_list
);
607 if (file
->f_flags
& O_NONBLOCK
) {
612 interruptible_sleep_on (&tty
->read_wait
);
613 if (signal_pending(current
)) {
619 if (rbuf
->count
> nr
)
620 /* frame too large for caller's buffer (discard frame) */
623 /* Copy the data to the caller's buffer */
624 if (copy_to_user(buf
, rbuf
->buf
, rbuf
->count
))
630 /* return HDLC buffer to free list unless the free list */
631 /* count has exceeded the default value, in which case the */
632 /* buffer is freed back to the OS to conserve memory */
633 if (n_hdlc
->rx_free_buf_list
.count
> DEFAULT_RX_BUF_COUNT
)
636 n_hdlc_buf_put(&n_hdlc
->rx_free_buf_list
,rbuf
);
640 } /* end of n_hdlc_tty_read() */
643 * n_hdlc_tty_write - write a single frame of data to device
644 * @tty - pointer to associated tty device instance data
645 * @file - pointer to file object data
646 * @data - pointer to transmit data (one frame)
647 * @count - size of transmit frame in bytes
649 * Returns the number of bytes written (or error code).
651 static ssize_t
n_hdlc_tty_write(struct tty_struct
*tty
, struct file
*file
,
652 const unsigned char *data
, size_t count
)
654 struct n_hdlc
*n_hdlc
= tty2n_hdlc (tty
);
656 DECLARE_WAITQUEUE(wait
, current
);
657 struct n_hdlc_buf
*tbuf
;
659 if (debuglevel
>= DEBUG_LEVEL_INFO
)
660 printk("%s(%d)n_hdlc_tty_write() called count=%Zd\n",
661 __FILE__
,__LINE__
,count
);
663 /* Verify pointers */
667 if (n_hdlc
->magic
!= HDLC_MAGIC
)
670 /* verify frame size */
671 if (count
> maxframe
) {
672 if (debuglevel
& DEBUG_LEVEL_INFO
)
674 "n_hdlc_tty_write: truncating user packet "
675 "from %lu to %d\n", (unsigned long) count
,
682 add_wait_queue(&tty
->write_wait
, &wait
);
683 set_current_state(TASK_INTERRUPTIBLE
);
685 /* Allocate transmit buffer */
686 /* sleep until transmit buffer available */
687 while (!(tbuf
= n_hdlc_buf_get(&n_hdlc
->tx_free_buf_list
))) {
688 if (file
->f_flags
& O_NONBLOCK
) {
694 n_hdlc
= tty2n_hdlc (tty
);
695 if (!n_hdlc
|| n_hdlc
->magic
!= HDLC_MAGIC
||
696 tty
!= n_hdlc
->tty
) {
697 printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc
);
702 if (signal_pending(current
)) {
708 set_current_state(TASK_RUNNING
);
709 remove_wait_queue(&tty
->write_wait
, &wait
);
712 /* Retrieve the user's buffer */
713 memcpy(tbuf
->buf
, data
, count
);
716 tbuf
->count
= error
= count
;
717 n_hdlc_buf_put(&n_hdlc
->tx_buf_list
,tbuf
);
718 n_hdlc_send_frames(n_hdlc
,tty
);
723 } /* end of n_hdlc_tty_write() */
726 * n_hdlc_tty_ioctl - process IOCTL system call for the tty device.
727 * @tty - pointer to tty instance data
728 * @file - pointer to open file object for device
729 * @cmd - IOCTL command code
730 * @arg - argument for IOCTL call (cmd dependent)
732 * Returns command dependent result.
734 static int n_hdlc_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
735 unsigned int cmd
, unsigned long arg
)
737 struct n_hdlc
*n_hdlc
= tty2n_hdlc (tty
);
742 if (debuglevel
>= DEBUG_LEVEL_INFO
)
743 printk("%s(%d)n_hdlc_tty_ioctl() called %d\n",
744 __FILE__
,__LINE__
,cmd
);
746 /* Verify the status of the device */
747 if (!n_hdlc
|| n_hdlc
->magic
!= HDLC_MAGIC
)
752 /* report count of read data available */
753 /* in next available frame (if any) */
754 spin_lock_irqsave(&n_hdlc
->rx_buf_list
.spinlock
,flags
);
755 if (n_hdlc
->rx_buf_list
.head
)
756 count
= n_hdlc
->rx_buf_list
.head
->count
;
759 spin_unlock_irqrestore(&n_hdlc
->rx_buf_list
.spinlock
,flags
);
760 error
= put_user(count
, (int __user
*)arg
);
764 /* get the pending tx byte count in the driver */
765 count
= tty_chars_in_buffer(tty
);
766 /* add size of next output frame in queue */
767 spin_lock_irqsave(&n_hdlc
->tx_buf_list
.spinlock
,flags
);
768 if (n_hdlc
->tx_buf_list
.head
)
769 count
+= n_hdlc
->tx_buf_list
.head
->count
;
770 spin_unlock_irqrestore(&n_hdlc
->tx_buf_list
.spinlock
,flags
);
771 error
= put_user(count
, (int __user
*)arg
);
780 /* fall through to default */
783 error
= n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
788 } /* end of n_hdlc_tty_ioctl() */
791 * n_hdlc_tty_poll - TTY callback for poll system call
792 * @tty - pointer to tty instance data
793 * @filp - pointer to open file object for device
794 * @poll_table - wait queue for operations
796 * Determine which operations (read/write) will not block and return info
798 * Returns a bit mask containing info on which ops will not block.
800 static unsigned int n_hdlc_tty_poll(struct tty_struct
*tty
, struct file
*filp
,
803 struct n_hdlc
*n_hdlc
= tty2n_hdlc (tty
);
804 unsigned int mask
= 0;
806 if (debuglevel
>= DEBUG_LEVEL_INFO
)
807 printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__
,__LINE__
);
809 if (n_hdlc
&& n_hdlc
->magic
== HDLC_MAGIC
&& tty
== n_hdlc
->tty
) {
810 /* queue current process into any wait queue that */
811 /* may awaken in the future (read and write) */
813 poll_wait(filp
, &tty
->read_wait
, wait
);
814 poll_wait(filp
, &tty
->write_wait
, wait
);
816 /* set bits for operations that won't block */
817 if (n_hdlc
->rx_buf_list
.head
)
818 mask
|= POLLIN
| POLLRDNORM
; /* readable */
819 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
821 if (tty_hung_up_p(filp
))
823 if (!tty_is_writelocked(tty
) &&
824 n_hdlc
->tx_free_buf_list
.head
)
825 mask
|= POLLOUT
| POLLWRNORM
; /* writable */
828 } /* end of n_hdlc_tty_poll() */
831 * n_hdlc_alloc - allocate an n_hdlc instance data structure
833 * Returns a pointer to newly created structure if success, otherwise %NULL
835 static struct n_hdlc
*n_hdlc_alloc(void)
837 struct n_hdlc_buf
*buf
;
839 struct n_hdlc
*n_hdlc
= kmalloc(sizeof(*n_hdlc
), GFP_KERNEL
);
844 memset(n_hdlc
, 0, sizeof(*n_hdlc
));
846 n_hdlc_buf_list_init(&n_hdlc
->rx_free_buf_list
);
847 n_hdlc_buf_list_init(&n_hdlc
->tx_free_buf_list
);
848 n_hdlc_buf_list_init(&n_hdlc
->rx_buf_list
);
849 n_hdlc_buf_list_init(&n_hdlc
->tx_buf_list
);
851 /* allocate free rx buffer list */
852 for(i
=0;i
<DEFAULT_RX_BUF_COUNT
;i
++) {
853 buf
= kmalloc(N_HDLC_BUF_SIZE
, GFP_KERNEL
);
855 n_hdlc_buf_put(&n_hdlc
->rx_free_buf_list
,buf
);
856 else if (debuglevel
>= DEBUG_LEVEL_INFO
)
857 printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__
,__LINE__
, i
);
860 /* allocate free tx buffer list */
861 for(i
=0;i
<DEFAULT_TX_BUF_COUNT
;i
++) {
862 buf
= kmalloc(N_HDLC_BUF_SIZE
, GFP_KERNEL
);
864 n_hdlc_buf_put(&n_hdlc
->tx_free_buf_list
,buf
);
865 else if (debuglevel
>= DEBUG_LEVEL_INFO
)
866 printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__
,__LINE__
, i
);
869 /* Initialize the control block */
870 n_hdlc
->magic
= HDLC_MAGIC
;
875 } /* end of n_hdlc_alloc() */
878 * n_hdlc_buf_list_init - initialize specified HDLC buffer list
879 * @list - pointer to buffer list
881 static void n_hdlc_buf_list_init(struct n_hdlc_buf_list
*list
)
883 memset(list
, 0, sizeof(*list
));
884 spin_lock_init(&list
->spinlock
);
885 } /* end of n_hdlc_buf_list_init() */
888 * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list
889 * @list - pointer to buffer list
890 * @buf - pointer to buffer
892 static void n_hdlc_buf_put(struct n_hdlc_buf_list
*list
,
893 struct n_hdlc_buf
*buf
)
896 spin_lock_irqsave(&list
->spinlock
,flags
);
900 list
->tail
->link
= buf
;
906 spin_unlock_irqrestore(&list
->spinlock
,flags
);
908 } /* end of n_hdlc_buf_put() */
911 * n_hdlc_buf_get - remove and return an HDLC buffer from list
912 * @list - pointer to HDLC buffer list
914 * Remove and return an HDLC buffer from the head of the specified HDLC buffer
916 * Returns a pointer to HDLC buffer if available, otherwise %NULL.
918 static struct n_hdlc_buf
* n_hdlc_buf_get(struct n_hdlc_buf_list
*list
)
921 struct n_hdlc_buf
*buf
;
922 spin_lock_irqsave(&list
->spinlock
,flags
);
926 list
->head
= buf
->link
;
932 spin_unlock_irqrestore(&list
->spinlock
,flags
);
935 } /* end of n_hdlc_buf_get() */
937 static char hdlc_banner
[] __initdata
=
938 KERN_INFO
"HDLC line discipline maxframe=%u\n";
939 static char hdlc_register_ok
[] __initdata
=
940 KERN_INFO
"N_HDLC line discipline registered.\n";
941 static char hdlc_register_fail
[] __initdata
=
942 KERN_ERR
"error registering line discipline: %d\n";
943 static char hdlc_init_fail
[] __initdata
=
944 KERN_INFO
"N_HDLC: init failure %d\n";
946 static int __init
n_hdlc_init(void)
950 /* range check maxframe arg */
953 else if (maxframe
> 65535)
956 printk(hdlc_banner
, maxframe
);
958 status
= tty_register_ldisc(N_HDLC
, &n_hdlc_ldisc
);
960 printk(hdlc_register_ok
);
962 printk(hdlc_register_fail
, status
);
965 printk(hdlc_init_fail
, status
);
968 } /* end of init_module() */
970 static char hdlc_unregister_ok
[] __exitdata
=
971 KERN_INFO
"N_HDLC: line discipline unregistered\n";
972 static char hdlc_unregister_fail
[] __exitdata
=
973 KERN_ERR
"N_HDLC: can't unregister line discipline (err = %d)\n";
975 static void __exit
n_hdlc_exit(void)
977 /* Release tty registration of line discipline */
978 int status
= tty_unregister_ldisc(N_HDLC
);
981 printk(hdlc_unregister_fail
, status
);
983 printk(hdlc_unregister_ok
);
986 module_init(n_hdlc_init
);
987 module_exit(n_hdlc_exit
);
989 MODULE_LICENSE("GPL");
990 MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com");
991 module_param(debuglevel
, int, 0);
992 module_param(maxframe
, int, 0);
993 MODULE_ALIAS_LDISC(N_HDLC
);