aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/tty/n_hdlc.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/tty/n_hdlc.c')
-rw-r--r--drivers/tty/n_hdlc.c1007
1 files changed, 1007 insertions, 0 deletions
diff --git a/drivers/tty/n_hdlc.c b/drivers/tty/n_hdlc.c
new file mode 100644
index 000000000000..47d32281032c
--- /dev/null
+++ b/drivers/tty/n_hdlc.c
@@ -0,0 +1,1007 @@
1/* generic HDLC line discipline for Linux
2 *
3 * Written by Paul Fulghum paulkf@microgate.com
4 * for Microgate Corporation
5 *
6 * Microgate and SyncLink are registered trademarks of Microgate Corporation
7 *
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>
11 *
12 * Original release 01/11/99
13 *
14 * This code is released under the GNU General Public License (GPL)
15 *
16 * This module implements the tty line discipline N_HDLC for use with
17 * tty device drivers that support bit-synchronous HDLC communications.
18 *
19 * All HDLC data is frame oriented which means:
20 *
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.
30 *
31 *
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.
37 *
38 * The HDLC line discipline queues the receive frames in separate
39 * buffers so complete receive frames can be returned by the
40 * tty read calls.
41 *
42 * 3. tty read calls returns an entire frame of data or nothing.
43 *
44 * 4. all send and receive data is considered raw. No processing
45 * or translation is performed by the line discipline, regardless
46 * of the tty flags
47 *
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).
52 *
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).
57 *
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
61 * conventions.
62 *
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.
66 *
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.
78 */
79
80#define HDLC_MAGIC 0x239e
81
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>
90
91#undef VERSION
92#define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch))
93
94#include <linux/poll.h>
95#include <linux/in.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>
105
106#include <asm/system.h>
107#include <asm/termios.h>
108#include <asm/uaccess.h>
109
110/*
111 * Buffers for individual HDLC frames
112 */
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
117
118struct n_hdlc_buf {
119 struct n_hdlc_buf *link;
120 int count;
121 char buf[1];
122};
123
124#define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe)
125
126struct n_hdlc_buf_list {
127 struct n_hdlc_buf *head;
128 struct n_hdlc_buf *tail;
129 int count;
130 spinlock_t spinlock;
131};
132
133/**
134 * struct n_hdlc - per device instance data structure
135 * @magic - magic value for structure
136 * @flags - miscellaneous control flags
137 * @tty - ptr to TTY structure
138 * @backup_tty - TTY to use if tty gets closed
139 * @tbusy - reentrancy flag for tx wakeup code
140 * @woke_up - FIXME: describe this field
141 * @tbuf - currently transmitting tx buffer
142 * @tx_buf_list - list of pending transmit frame buffers
143 * @rx_buf_list - list of received frame buffers
144 * @tx_free_buf_list - list unused transmit frame buffers
145 * @rx_free_buf_list - list unused received frame buffers
146 */
147struct n_hdlc {
148 int magic;
149 __u32 flags;
150 struct tty_struct *tty;
151 struct tty_struct *backup_tty;
152 int tbusy;
153 int woke_up;
154 struct n_hdlc_buf *tbuf;
155 struct n_hdlc_buf_list tx_buf_list;
156 struct n_hdlc_buf_list rx_buf_list;
157 struct n_hdlc_buf_list tx_free_buf_list;
158 struct n_hdlc_buf_list rx_free_buf_list;
159};
160
161/*
162 * HDLC buffer list manipulation functions
163 */
164static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list);
165static void n_hdlc_buf_put(struct n_hdlc_buf_list *list,
166 struct n_hdlc_buf *buf);
167static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list);
168
169/* Local functions */
170
171static struct n_hdlc *n_hdlc_alloc (void);
172
173/* debug level can be set by insmod for debugging purposes */
174#define DEBUG_LEVEL_INFO 1
175static int debuglevel;
176
177/* max frame size for memory allocations */
178static int maxframe = 4096;
179
180/* TTY callbacks */
181
182static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
183 __u8 __user *buf, size_t nr);
184static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
185 const unsigned char *buf, size_t nr);
186static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
187 unsigned int cmd, unsigned long arg);
188static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
189 poll_table *wait);
190static int n_hdlc_tty_open(struct tty_struct *tty);
191static void n_hdlc_tty_close(struct tty_struct *tty);
192static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp,
193 char *fp, int count);
194static void n_hdlc_tty_wakeup(struct tty_struct *tty);
195
196#define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f)))
197
198#define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data))
199#define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty)
200
201static void flush_rx_queue(struct tty_struct *tty)
202{
203 struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
204 struct n_hdlc_buf *buf;
205
206 while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list)))
207 n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf);
208}
209
210static void flush_tx_queue(struct tty_struct *tty)
211{
212 struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
213 struct n_hdlc_buf *buf;
214 unsigned long flags;
215
216 while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list)))
217 n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf);
218 spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
219 if (n_hdlc->tbuf) {
220 n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, n_hdlc->tbuf);
221 n_hdlc->tbuf = NULL;
222 }
223 spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
224}
225
226static struct tty_ldisc_ops n_hdlc_ldisc = {
227 .owner = THIS_MODULE,
228 .magic = TTY_LDISC_MAGIC,
229 .name = "hdlc",
230 .open = n_hdlc_tty_open,
231 .close = n_hdlc_tty_close,
232 .read = n_hdlc_tty_read,
233 .write = n_hdlc_tty_write,
234 .ioctl = n_hdlc_tty_ioctl,
235 .poll = n_hdlc_tty_poll,
236 .receive_buf = n_hdlc_tty_receive,
237 .write_wakeup = n_hdlc_tty_wakeup,
238 .flush_buffer = flush_rx_queue,
239};
240
241/**
242 * n_hdlc_release - release an n_hdlc per device line discipline info structure
243 * @n_hdlc - per device line discipline info structure
244 */
245static void n_hdlc_release(struct n_hdlc *n_hdlc)
246{
247 struct tty_struct *tty = n_hdlc2tty (n_hdlc);
248 struct n_hdlc_buf *buf;
249
250 if (debuglevel >= DEBUG_LEVEL_INFO)
251 printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__);
252
253 /* Ensure that the n_hdlcd process is not hanging on select()/poll() */
254 wake_up_interruptible (&tty->read_wait);
255 wake_up_interruptible (&tty->write_wait);
256
257 if (tty->disc_data == n_hdlc)
258 tty->disc_data = NULL; /* Break the tty->n_hdlc link */
259
260 /* Release transmit and receive buffers */
261 for(;;) {
262 buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
263 if (buf) {
264 kfree(buf);
265 } else
266 break;
267 }
268 for(;;) {
269 buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list);
270 if (buf) {
271 kfree(buf);
272 } else
273 break;
274 }
275 for(;;) {
276 buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
277 if (buf) {
278 kfree(buf);
279 } else
280 break;
281 }
282 for(;;) {
283 buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
284 if (buf) {
285 kfree(buf);
286 } else
287 break;
288 }
289 kfree(n_hdlc->tbuf);
290 kfree(n_hdlc);
291
292} /* end of n_hdlc_release() */
293
294/**
295 * n_hdlc_tty_close - line discipline close
296 * @tty - pointer to tty info structure
297 *
298 * Called when the line discipline is changed to something
299 * else, the tty is closed, or the tty detects a hangup.
300 */
301static void n_hdlc_tty_close(struct tty_struct *tty)
302{
303 struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
304
305 if (debuglevel >= DEBUG_LEVEL_INFO)
306 printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__);
307
308 if (n_hdlc != NULL) {
309 if (n_hdlc->magic != HDLC_MAGIC) {
310 printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n");
311 return;
312 }
313#if defined(TTY_NO_WRITE_SPLIT)
314 clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags);
315#endif
316 tty->disc_data = NULL;
317 if (tty == n_hdlc->backup_tty)
318 n_hdlc->backup_tty = NULL;
319 if (tty != n_hdlc->tty)
320 return;
321 if (n_hdlc->backup_tty) {
322 n_hdlc->tty = n_hdlc->backup_tty;
323 } else {
324 n_hdlc_release (n_hdlc);
325 }
326 }
327
328 if (debuglevel >= DEBUG_LEVEL_INFO)
329 printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__);
330
331} /* end of n_hdlc_tty_close() */
332
333/**
334 * n_hdlc_tty_open - called when line discipline changed to n_hdlc
335 * @tty - pointer to tty info structure
336 *
337 * Returns 0 if success, otherwise error code
338 */
339static int n_hdlc_tty_open (struct tty_struct *tty)
340{
341 struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
342
343 if (debuglevel >= DEBUG_LEVEL_INFO)
344 printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n",
345 __FILE__,__LINE__,
346 tty->name);
347
348 /* There should not be an existing table for this slot. */
349 if (n_hdlc) {
350 printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" );
351 return -EEXIST;
352 }
353
354 n_hdlc = n_hdlc_alloc();
355 if (!n_hdlc) {
356 printk (KERN_ERR "n_hdlc_alloc failed\n");
357 return -ENFILE;
358 }
359
360 tty->disc_data = n_hdlc;
361 n_hdlc->tty = tty;
362 tty->receive_room = 65536;
363
364#if defined(TTY_NO_WRITE_SPLIT)
365 /* change tty_io write() to not split large writes into 8K chunks */
366 set_bit(TTY_NO_WRITE_SPLIT,&tty->flags);
367#endif
368
369 /* flush receive data from driver */
370 tty_driver_flush_buffer(tty);
371
372 if (debuglevel >= DEBUG_LEVEL_INFO)
373 printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__);
374
375 return 0;
376
377} /* end of n_tty_hdlc_open() */
378
379/**
380 * n_hdlc_send_frames - send frames on pending send buffer list
381 * @n_hdlc - pointer to ldisc instance data
382 * @tty - pointer to tty instance data
383 *
384 * Send frames on pending send buffer list until the driver does not accept a
385 * frame (busy) this function is called after adding a frame to the send buffer
386 * list and by the tty wakeup callback.
387 */
388static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)
389{
390 register int actual;
391 unsigned long flags;
392 struct n_hdlc_buf *tbuf;
393
394 if (debuglevel >= DEBUG_LEVEL_INFO)
395 printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__);
396 check_again:
397
398 spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
399 if (n_hdlc->tbusy) {
400 n_hdlc->woke_up = 1;
401 spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
402 return;
403 }
404 n_hdlc->tbusy = 1;
405 n_hdlc->woke_up = 0;
406 spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
407
408 /* get current transmit buffer or get new transmit */
409 /* buffer from list of pending transmit buffers */
410
411 tbuf = n_hdlc->tbuf;
412 if (!tbuf)
413 tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
414
415 while (tbuf) {
416 if (debuglevel >= DEBUG_LEVEL_INFO)
417 printk("%s(%d)sending frame %p, count=%d\n",
418 __FILE__,__LINE__,tbuf,tbuf->count);
419
420 /* Send the next block of data to device */
421 tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
422 actual = tty->ops->write(tty, tbuf->buf, tbuf->count);
423
424 /* rollback was possible and has been done */
425 if (actual == -ERESTARTSYS) {
426 n_hdlc->tbuf = tbuf;
427 break;
428 }
429 /* if transmit error, throw frame away by */
430 /* pretending it was accepted by driver */
431 if (actual < 0)
432 actual = tbuf->count;
433
434 if (actual == tbuf->count) {
435 if (debuglevel >= DEBUG_LEVEL_INFO)
436 printk("%s(%d)frame %p completed\n",
437 __FILE__,__LINE__,tbuf);
438
439 /* free current transmit buffer */
440 n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf);
441
442 /* this tx buffer is done */
443 n_hdlc->tbuf = NULL;
444
445 /* wait up sleeping writers */
446 wake_up_interruptible(&tty->write_wait);
447
448 /* get next pending transmit buffer */
449 tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
450 } else {
451 if (debuglevel >= DEBUG_LEVEL_INFO)
452 printk("%s(%d)frame %p pending\n",
453 __FILE__,__LINE__,tbuf);
454
455 /* buffer not accepted by driver */
456 /* set this buffer as pending buffer */
457 n_hdlc->tbuf = tbuf;
458 break;
459 }
460 }
461
462 if (!tbuf)
463 tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
464
465 /* Clear the re-entry flag */
466 spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
467 n_hdlc->tbusy = 0;
468 spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
469
470 if (n_hdlc->woke_up)
471 goto check_again;
472
473 if (debuglevel >= DEBUG_LEVEL_INFO)
474 printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__);
475
476} /* end of n_hdlc_send_frames() */
477
478/**
479 * n_hdlc_tty_wakeup - Callback for transmit wakeup
480 * @tty - pointer to associated tty instance data
481 *
482 * Called when low level device driver can accept more send data.
483 */
484static void n_hdlc_tty_wakeup(struct tty_struct *tty)
485{
486 struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
487
488 if (debuglevel >= DEBUG_LEVEL_INFO)
489 printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__);
490
491 if (!n_hdlc)
492 return;
493
494 if (tty != n_hdlc->tty) {
495 tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
496 return;
497 }
498
499 n_hdlc_send_frames (n_hdlc, tty);
500
501} /* end of n_hdlc_tty_wakeup() */
502
503/**
504 * n_hdlc_tty_receive - Called by tty driver when receive data is available
505 * @tty - pointer to tty instance data
506 * @data - pointer to received data
507 * @flags - pointer to flags for data
508 * @count - count of received data in bytes
509 *
510 * Called by tty low level driver when receive data is available. Data is
511 * interpreted as one HDLC frame.
512 */
513static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data,
514 char *flags, int count)
515{
516 register struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
517 register struct n_hdlc_buf *buf;
518
519 if (debuglevel >= DEBUG_LEVEL_INFO)
520 printk("%s(%d)n_hdlc_tty_receive() called count=%d\n",
521 __FILE__,__LINE__, count);
522
523 /* This can happen if stuff comes in on the backup tty */
524 if (!n_hdlc || tty != n_hdlc->tty)
525 return;
526
527 /* verify line is using HDLC discipline */
528 if (n_hdlc->magic != HDLC_MAGIC) {
529 printk("%s(%d) line not using HDLC discipline\n",
530 __FILE__,__LINE__);
531 return;
532 }
533
534 if ( count>maxframe ) {
535 if (debuglevel >= DEBUG_LEVEL_INFO)
536 printk("%s(%d) rx count>maxframesize, data discarded\n",
537 __FILE__,__LINE__);
538 return;
539 }
540
541 /* get a free HDLC buffer */
542 buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
543 if (!buf) {
544 /* no buffers in free list, attempt to allocate another rx buffer */
545 /* unless the maximum count has been reached */
546 if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT)
547 buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC);
548 }
549
550 if (!buf) {
551 if (debuglevel >= DEBUG_LEVEL_INFO)
552 printk("%s(%d) no more rx buffers, data discarded\n",
553 __FILE__,__LINE__);
554 return;
555 }
556
557 /* copy received data to HDLC buffer */
558 memcpy(buf->buf,data,count);
559 buf->count=count;
560
561 /* add HDLC buffer to list of received frames */
562 n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf);
563
564 /* wake up any blocked reads and perform async signalling */
565 wake_up_interruptible (&tty->read_wait);
566 if (n_hdlc->tty->fasync != NULL)
567 kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN);
568
569} /* end of n_hdlc_tty_receive() */
570
571/**
572 * n_hdlc_tty_read - Called to retrieve one frame of data (if available)
573 * @tty - pointer to tty instance data
574 * @file - pointer to open file object
575 * @buf - pointer to returned data buffer
576 * @nr - size of returned data buffer
577 *
578 * Returns the number of bytes returned or error code.
579 */
580static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
581 __u8 __user *buf, size_t nr)
582{
583 struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
584 int ret;
585 struct n_hdlc_buf *rbuf;
586
587 if (debuglevel >= DEBUG_LEVEL_INFO)
588 printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__);
589
590 /* Validate the pointers */
591 if (!n_hdlc)
592 return -EIO;
593
594 /* verify user access to buffer */
595 if (!access_ok(VERIFY_WRITE, buf, nr)) {
596 printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user "
597 "buffer\n", __FILE__, __LINE__);
598 return -EFAULT;
599 }
600
601 tty_lock();
602
603 for (;;) {
604 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
605 tty_unlock();
606 return -EIO;
607 }
608
609 n_hdlc = tty2n_hdlc (tty);
610 if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC ||
611 tty != n_hdlc->tty) {
612 tty_unlock();
613 return 0;
614 }
615
616 rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
617 if (rbuf)
618 break;
619
620 /* no data */
621 if (file->f_flags & O_NONBLOCK) {
622 tty_unlock();
623 return -EAGAIN;
624 }
625
626 interruptible_sleep_on (&tty->read_wait);
627 if (signal_pending(current)) {
628 tty_unlock();
629 return -EINTR;
630 }
631 }
632
633 if (rbuf->count > nr)
634 /* frame too large for caller's buffer (discard frame) */
635 ret = -EOVERFLOW;
636 else {
637 /* Copy the data to the caller's buffer */
638 if (copy_to_user(buf, rbuf->buf, rbuf->count))
639 ret = -EFAULT;
640 else
641 ret = rbuf->count;
642 }
643
644 /* return HDLC buffer to free list unless the free list */
645 /* count has exceeded the default value, in which case the */
646 /* buffer is freed back to the OS to conserve memory */
647 if (n_hdlc->rx_free_buf_list.count > DEFAULT_RX_BUF_COUNT)
648 kfree(rbuf);
649 else
650 n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,rbuf);
651 tty_unlock();
652 return ret;
653
654} /* end of n_hdlc_tty_read() */
655
656/**
657 * n_hdlc_tty_write - write a single frame of data to device
658 * @tty - pointer to associated tty device instance data
659 * @file - pointer to file object data
660 * @data - pointer to transmit data (one frame)
661 * @count - size of transmit frame in bytes
662 *
663 * Returns the number of bytes written (or error code).
664 */
665static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
666 const unsigned char *data, size_t count)
667{
668 struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
669 int error = 0;
670 DECLARE_WAITQUEUE(wait, current);
671 struct n_hdlc_buf *tbuf;
672
673 if (debuglevel >= DEBUG_LEVEL_INFO)
674 printk("%s(%d)n_hdlc_tty_write() called count=%Zd\n",
675 __FILE__,__LINE__,count);
676
677 /* Verify pointers */
678 if (!n_hdlc)
679 return -EIO;
680
681 if (n_hdlc->magic != HDLC_MAGIC)
682 return -EIO;
683
684 /* verify frame size */
685 if (count > maxframe ) {
686 if (debuglevel & DEBUG_LEVEL_INFO)
687 printk (KERN_WARNING
688 "n_hdlc_tty_write: truncating user packet "
689 "from %lu to %d\n", (unsigned long) count,
690 maxframe );
691 count = maxframe;
692 }
693
694 tty_lock();
695
696 add_wait_queue(&tty->write_wait, &wait);
697 set_current_state(TASK_INTERRUPTIBLE);
698
699 /* Allocate transmit buffer */
700 /* sleep until transmit buffer available */
701 while (!(tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list))) {
702 if (file->f_flags & O_NONBLOCK) {
703 error = -EAGAIN;
704 break;
705 }
706 schedule();
707
708 n_hdlc = tty2n_hdlc (tty);
709 if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC ||
710 tty != n_hdlc->tty) {
711 printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc);
712 error = -EIO;
713 break;
714 }
715
716 if (signal_pending(current)) {
717 error = -EINTR;
718 break;
719 }
720 }
721
722 set_current_state(TASK_RUNNING);
723 remove_wait_queue(&tty->write_wait, &wait);
724
725 if (!error) {
726 /* Retrieve the user's buffer */
727 memcpy(tbuf->buf, data, count);
728
729 /* Send the data */
730 tbuf->count = error = count;
731 n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf);
732 n_hdlc_send_frames(n_hdlc,tty);
733 }
734 tty_unlock();
735 return error;
736
737} /* end of n_hdlc_tty_write() */
738
739/**
740 * n_hdlc_tty_ioctl - process IOCTL system call for the tty device.
741 * @tty - pointer to tty instance data
742 * @file - pointer to open file object for device
743 * @cmd - IOCTL command code
744 * @arg - argument for IOCTL call (cmd dependent)
745 *
746 * Returns command dependent result.
747 */
748static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
749 unsigned int cmd, unsigned long arg)
750{
751 struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
752 int error = 0;
753 int count;
754 unsigned long flags;
755
756 if (debuglevel >= DEBUG_LEVEL_INFO)
757 printk("%s(%d)n_hdlc_tty_ioctl() called %d\n",
758 __FILE__,__LINE__,cmd);
759
760 /* Verify the status of the device */
761 if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC)
762 return -EBADF;
763
764 switch (cmd) {
765 case FIONREAD:
766 /* report count of read data available */
767 /* in next available frame (if any) */
768 spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags);
769 if (n_hdlc->rx_buf_list.head)
770 count = n_hdlc->rx_buf_list.head->count;
771 else
772 count = 0;
773 spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags);
774 error = put_user(count, (int __user *)arg);
775 break;
776
777 case TIOCOUTQ:
778 /* get the pending tx byte count in the driver */
779 count = tty_chars_in_buffer(tty);
780 /* add size of next output frame in queue */
781 spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags);
782 if (n_hdlc->tx_buf_list.head)
783 count += n_hdlc->tx_buf_list.head->count;
784 spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags);
785 error = put_user(count, (int __user *)arg);
786 break;
787
788 case TCFLSH:
789 switch (arg) {
790 case TCIOFLUSH:
791 case TCOFLUSH:
792 flush_tx_queue(tty);
793 }
794 /* fall through to default */
795
796 default:
797 error = n_tty_ioctl_helper(tty, file, cmd, arg);
798 break;
799 }
800 return error;
801
802} /* end of n_hdlc_tty_ioctl() */
803
804/**
805 * n_hdlc_tty_poll - TTY callback for poll system call
806 * @tty - pointer to tty instance data
807 * @filp - pointer to open file object for device
808 * @poll_table - wait queue for operations
809 *
810 * Determine which operations (read/write) will not block and return info
811 * to caller.
812 * Returns a bit mask containing info on which ops will not block.
813 */
814static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
815 poll_table *wait)
816{
817 struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
818 unsigned int mask = 0;
819
820 if (debuglevel >= DEBUG_LEVEL_INFO)
821 printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__);
822
823 if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) {
824 /* queue current process into any wait queue that */
825 /* may awaken in the future (read and write) */
826
827 poll_wait(filp, &tty->read_wait, wait);
828 poll_wait(filp, &tty->write_wait, wait);
829
830 /* set bits for operations that won't block */
831 if (n_hdlc->rx_buf_list.head)
832 mask |= POLLIN | POLLRDNORM; /* readable */
833 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
834 mask |= POLLHUP;
835 if (tty_hung_up_p(filp))
836 mask |= POLLHUP;
837 if (!tty_is_writelocked(tty) &&
838 n_hdlc->tx_free_buf_list.head)
839 mask |= POLLOUT | POLLWRNORM; /* writable */
840 }
841 return mask;
842} /* end of n_hdlc_tty_poll() */
843
844/**
845 * n_hdlc_alloc - allocate an n_hdlc instance data structure
846 *
847 * Returns a pointer to newly created structure if success, otherwise %NULL
848 */
849static struct n_hdlc *n_hdlc_alloc(void)
850{
851 struct n_hdlc_buf *buf;
852 int i;
853 struct n_hdlc *n_hdlc = kmalloc(sizeof(*n_hdlc), GFP_KERNEL);
854
855 if (!n_hdlc)
856 return NULL;
857
858 memset(n_hdlc, 0, sizeof(*n_hdlc));
859
860 n_hdlc_buf_list_init(&n_hdlc->rx_free_buf_list);
861 n_hdlc_buf_list_init(&n_hdlc->tx_free_buf_list);
862 n_hdlc_buf_list_init(&n_hdlc->rx_buf_list);
863 n_hdlc_buf_list_init(&n_hdlc->tx_buf_list);
864
865 /* allocate free rx buffer list */
866 for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) {
867 buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL);
868 if (buf)
869 n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf);
870 else if (debuglevel >= DEBUG_LEVEL_INFO)
871 printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i);
872 }
873
874 /* allocate free tx buffer list */
875 for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) {
876 buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL);
877 if (buf)
878 n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf);
879 else if (debuglevel >= DEBUG_LEVEL_INFO)
880 printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i);
881 }
882
883 /* Initialize the control block */
884 n_hdlc->magic = HDLC_MAGIC;
885 n_hdlc->flags = 0;
886
887 return n_hdlc;
888
889} /* end of n_hdlc_alloc() */
890
891/**
892 * n_hdlc_buf_list_init - initialize specified HDLC buffer list
893 * @list - pointer to buffer list
894 */
895static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list)
896{
897 memset(list, 0, sizeof(*list));
898 spin_lock_init(&list->spinlock);
899} /* end of n_hdlc_buf_list_init() */
900
901/**
902 * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list
903 * @list - pointer to buffer list
904 * @buf - pointer to buffer
905 */
906static void n_hdlc_buf_put(struct n_hdlc_buf_list *list,
907 struct n_hdlc_buf *buf)
908{
909 unsigned long flags;
910 spin_lock_irqsave(&list->spinlock,flags);
911
912 buf->link=NULL;
913 if (list->tail)
914 list->tail->link = buf;
915 else
916 list->head = buf;
917 list->tail = buf;
918 (list->count)++;
919
920 spin_unlock_irqrestore(&list->spinlock,flags);
921
922} /* end of n_hdlc_buf_put() */
923
924/**
925 * n_hdlc_buf_get - remove and return an HDLC buffer from list
926 * @list - pointer to HDLC buffer list
927 *
928 * Remove and return an HDLC buffer from the head of the specified HDLC buffer
929 * list.
930 * Returns a pointer to HDLC buffer if available, otherwise %NULL.
931 */
932static struct n_hdlc_buf* n_hdlc_buf_get(struct n_hdlc_buf_list *list)
933{
934 unsigned long flags;
935 struct n_hdlc_buf *buf;
936 spin_lock_irqsave(&list->spinlock,flags);
937
938 buf = list->head;
939 if (buf) {
940 list->head = buf->link;
941 (list->count)--;
942 }
943 if (!list->head)
944 list->tail = NULL;
945
946 spin_unlock_irqrestore(&list->spinlock,flags);
947 return buf;
948
949} /* end of n_hdlc_buf_get() */
950
951static char hdlc_banner[] __initdata =
952 KERN_INFO "HDLC line discipline maxframe=%u\n";
953static char hdlc_register_ok[] __initdata =
954 KERN_INFO "N_HDLC line discipline registered.\n";
955static char hdlc_register_fail[] __initdata =
956 KERN_ERR "error registering line discipline: %d\n";
957static char hdlc_init_fail[] __initdata =
958 KERN_INFO "N_HDLC: init failure %d\n";
959
960static int __init n_hdlc_init(void)
961{
962 int status;
963
964 /* range check maxframe arg */
965 if (maxframe < 4096)
966 maxframe = 4096;
967 else if (maxframe > 65535)
968 maxframe = 65535;
969
970 printk(hdlc_banner, maxframe);
971
972 status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc);
973 if (!status)
974 printk(hdlc_register_ok);
975 else
976 printk(hdlc_register_fail, status);
977
978 if (status)
979 printk(hdlc_init_fail, status);
980 return status;
981
982} /* end of init_module() */
983
984static char hdlc_unregister_ok[] __exitdata =
985 KERN_INFO "N_HDLC: line discipline unregistered\n";
986static char hdlc_unregister_fail[] __exitdata =
987 KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n";
988
989static void __exit n_hdlc_exit(void)
990{
991 /* Release tty registration of line discipline */
992 int status = tty_unregister_ldisc(N_HDLC);
993
994 if (status)
995 printk(hdlc_unregister_fail, status);
996 else
997 printk(hdlc_unregister_ok);
998}
999
1000module_init(n_hdlc_init);
1001module_exit(n_hdlc_exit);
1002
1003MODULE_LICENSE("GPL");
1004MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com");
1005module_param(debuglevel, int, 0);
1006module_param(maxframe, int, 0);
1007MODULE_ALIAS_LDISC(N_HDLC);
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-29 02:01:49 -0500