blob: 7b2a466616d6ef7acb2bc3ce8d773be9e4446375 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070013 *
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070081
Linus Torvalds1da177e2005-04-16 15:20:36 -070082#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/string.h> /* used in new tty drivers */
101#include <linux/signal.h> /* used in new tty drivers */
102#include <linux/if.h>
103#include <linux/bitops.h>
104
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105#include <asm/termios.h>
Linus Torvalds7c0f6ba2016-12-24 11:46:01 -0800106#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107
108/*
109 * Buffers for individual HDLC frames
110 */
111#define MAX_HDLC_FRAME_SIZE 65535
112#define DEFAULT_RX_BUF_COUNT 10
113#define MAX_RX_BUF_COUNT 60
Paul Fulghumbe10eb72009-06-22 18:42:56 +0100114#define DEFAULT_TX_BUF_COUNT 3
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115
116struct n_hdlc_buf {
Alexander Popov82f23412017-02-28 19:54:40 +0300117 struct list_head list_item;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 int count;
119 char buf[1];
120};
121
122#define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe)
123
124struct n_hdlc_buf_list {
Alexander Popov82f23412017-02-28 19:54:40 +0300125 struct list_head list;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 int count;
127 spinlock_t spinlock;
128};
129
130/**
131 * struct n_hdlc - per device instance data structure
132 * @magic - magic value for structure
133 * @flags - miscellaneous control flags
134 * @tty - ptr to TTY structure
135 * @backup_tty - TTY to use if tty gets closed
136 * @tbusy - reentrancy flag for tx wakeup code
137 * @woke_up - FIXME: describe this field
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 * @tx_buf_list - list of pending transmit frame buffers
139 * @rx_buf_list - list of received frame buffers
140 * @tx_free_buf_list - list unused transmit frame buffers
141 * @rx_free_buf_list - list unused received frame buffers
142 */
143struct n_hdlc {
144 int magic;
145 __u32 flags;
146 struct tty_struct *tty;
147 struct tty_struct *backup_tty;
148 int tbusy;
149 int woke_up;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 struct n_hdlc_buf_list tx_buf_list;
151 struct n_hdlc_buf_list rx_buf_list;
152 struct n_hdlc_buf_list tx_free_buf_list;
153 struct n_hdlc_buf_list rx_free_buf_list;
154};
155
156/*
157 * HDLC buffer list manipulation functions
158 */
Alexander Popov82f23412017-02-28 19:54:40 +0300159static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list,
160 struct n_hdlc_buf *buf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161static void n_hdlc_buf_put(struct n_hdlc_buf_list *list,
162 struct n_hdlc_buf *buf);
163static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list);
164
165/* Local functions */
166
167static struct n_hdlc *n_hdlc_alloc (void);
168
169/* debug level can be set by insmod for debugging purposes */
170#define DEBUG_LEVEL_INFO 1
171static int debuglevel;
172
173/* max frame size for memory allocations */
174static int maxframe = 4096;
175
176/* TTY callbacks */
177
178static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
179 __u8 __user *buf, size_t nr);
180static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
181 const unsigned char *buf, size_t nr);
182static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
183 unsigned int cmd, unsigned long arg);
184static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
185 poll_table *wait);
186static int n_hdlc_tty_open(struct tty_struct *tty);
187static void n_hdlc_tty_close(struct tty_struct *tty);
Linus Torvalds55db4c62011-06-04 06:33:24 +0900188static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp,
189 char *fp, int count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190static void n_hdlc_tty_wakeup(struct tty_struct *tty);
191
192#define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f)))
193
194#define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data))
195#define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty)
196
Paul Fulghumbe10eb72009-06-22 18:42:56 +0100197static void flush_rx_queue(struct tty_struct *tty)
198{
199 struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
200 struct n_hdlc_buf *buf;
201
202 while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list)))
203 n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf);
204}
205
206static void flush_tx_queue(struct tty_struct *tty)
207{
208 struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
209 struct n_hdlc_buf *buf;
Paul Fulghumbe10eb72009-06-22 18:42:56 +0100210
211 while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list)))
212 n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf);
Paul Fulghumbe10eb72009-06-22 18:42:56 +0100213}
214
Alan Coxa352def2008-07-16 21:53:12 +0100215static struct tty_ldisc_ops n_hdlc_ldisc = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 .owner = THIS_MODULE,
217 .magic = TTY_LDISC_MAGIC,
218 .name = "hdlc",
219 .open = n_hdlc_tty_open,
220 .close = n_hdlc_tty_close,
221 .read = n_hdlc_tty_read,
222 .write = n_hdlc_tty_write,
223 .ioctl = n_hdlc_tty_ioctl,
224 .poll = n_hdlc_tty_poll,
225 .receive_buf = n_hdlc_tty_receive,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 .write_wakeup = n_hdlc_tty_wakeup,
Paul Fulghumbe10eb72009-06-22 18:42:56 +0100227 .flush_buffer = flush_rx_queue,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228};
229
230/**
231 * n_hdlc_release - release an n_hdlc per device line discipline info structure
232 * @n_hdlc - per device line discipline info structure
233 */
234static void n_hdlc_release(struct n_hdlc *n_hdlc)
235{
236 struct tty_struct *tty = n_hdlc2tty (n_hdlc);
237 struct n_hdlc_buf *buf;
238
239 if (debuglevel >= DEBUG_LEVEL_INFO)
240 printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__);
241
242 /* Ensure that the n_hdlcd process is not hanging on select()/poll() */
243 wake_up_interruptible (&tty->read_wait);
244 wake_up_interruptible (&tty->write_wait);
245
Adrian Bunk827afdf2007-10-16 23:29:25 -0700246 if (tty->disc_data == n_hdlc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 tty->disc_data = NULL; /* Break the tty->n_hdlc link */
248
249 /* Release transmit and receive buffers */
250 for(;;) {
251 buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
252 if (buf) {
253 kfree(buf);
254 } else
255 break;
256 }
257 for(;;) {
258 buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list);
259 if (buf) {
260 kfree(buf);
261 } else
262 break;
263 }
264 for(;;) {
265 buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
266 if (buf) {
267 kfree(buf);
268 } else
269 break;
270 }
271 for(;;) {
272 buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
273 if (buf) {
274 kfree(buf);
275 } else
276 break;
277 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 kfree(n_hdlc);
279
280} /* end of n_hdlc_release() */
281
282/**
283 * n_hdlc_tty_close - line discipline close
284 * @tty - pointer to tty info structure
285 *
286 * Called when the line discipline is changed to something
287 * else, the tty is closed, or the tty detects a hangup.
288 */
289static void n_hdlc_tty_close(struct tty_struct *tty)
290{
291 struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
292
293 if (debuglevel >= DEBUG_LEVEL_INFO)
294 printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__);
295
296 if (n_hdlc != NULL) {
297 if (n_hdlc->magic != HDLC_MAGIC) {
298 printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n");
299 return;
300 }
301#if defined(TTY_NO_WRITE_SPLIT)
302 clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags);
303#endif
304 tty->disc_data = NULL;
305 if (tty == n_hdlc->backup_tty)
306 n_hdlc->backup_tty = NULL;
307 if (tty != n_hdlc->tty)
308 return;
309 if (n_hdlc->backup_tty) {
310 n_hdlc->tty = n_hdlc->backup_tty;
311 } else {
312 n_hdlc_release (n_hdlc);
313 }
314 }
315
316 if (debuglevel >= DEBUG_LEVEL_INFO)
317 printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__);
318
319} /* end of n_hdlc_tty_close() */
320
321/**
322 * n_hdlc_tty_open - called when line discipline changed to n_hdlc
323 * @tty - pointer to tty info structure
324 *
325 * Returns 0 if success, otherwise error code
326 */
327static int n_hdlc_tty_open (struct tty_struct *tty)
328{
329 struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
330
331 if (debuglevel >= DEBUG_LEVEL_INFO)
332 printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n",
333 __FILE__,__LINE__,
334 tty->name);
335
336 /* There should not be an existing table for this slot. */
337 if (n_hdlc) {
338 printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" );
339 return -EEXIST;
340 }
341
342 n_hdlc = n_hdlc_alloc();
343 if (!n_hdlc) {
344 printk (KERN_ERR "n_hdlc_alloc failed\n");
345 return -ENFILE;
346 }
347
348 tty->disc_data = n_hdlc;
349 n_hdlc->tty = tty;
Alan Cox33f0f882006-01-09 20:54:13 -0800350 tty->receive_room = 65536;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351
352#if defined(TTY_NO_WRITE_SPLIT)
353 /* change tty_io write() to not split large writes into 8K chunks */
354 set_bit(TTY_NO_WRITE_SPLIT,&tty->flags);
355#endif
356
Paul Fulghumbe10eb72009-06-22 18:42:56 +0100357 /* flush receive data from driver */
Alan Coxf34d7a52008-04-30 00:54:13 -0700358 tty_driver_flush_buffer(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359
360 if (debuglevel >= DEBUG_LEVEL_INFO)
361 printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__);
362
363 return 0;
364
365} /* end of n_tty_hdlc_open() */
366
367/**
368 * n_hdlc_send_frames - send frames on pending send buffer list
369 * @n_hdlc - pointer to ldisc instance data
370 * @tty - pointer to tty instance data
371 *
372 * Send frames on pending send buffer list until the driver does not accept a
373 * frame (busy) this function is called after adding a frame to the send buffer
374 * list and by the tty wakeup callback.
375 */
376static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)
377{
378 register int actual;
379 unsigned long flags;
380 struct n_hdlc_buf *tbuf;
381
382 if (debuglevel >= DEBUG_LEVEL_INFO)
383 printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__);
384 check_again:
385
386 spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
387 if (n_hdlc->tbusy) {
388 n_hdlc->woke_up = 1;
389 spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
390 return;
391 }
392 n_hdlc->tbusy = 1;
393 n_hdlc->woke_up = 0;
394 spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
395
Alexander Popov82f23412017-02-28 19:54:40 +0300396 tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 while (tbuf) {
398 if (debuglevel >= DEBUG_LEVEL_INFO)
399 printk("%s(%d)sending frame %p, count=%d\n",
400 __FILE__,__LINE__,tbuf,tbuf->count);
401
402 /* Send the next block of data to device */
Ilya Zykov7962fce2011-11-07 11:32:46 +0400403 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
Alan Coxf34d7a52008-04-30 00:54:13 -0700404 actual = tty->ops->write(tty, tbuf->buf, tbuf->count);
Jiri Slabyb0fed312007-07-15 23:40:12 -0700405
406 /* rollback was possible and has been done */
407 if (actual == -ERESTARTSYS) {
Alexander Popov82f23412017-02-28 19:54:40 +0300408 n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf);
Jiri Slabyb0fed312007-07-15 23:40:12 -0700409 break;
410 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 /* if transmit error, throw frame away by */
412 /* pretending it was accepted by driver */
413 if (actual < 0)
414 actual = tbuf->count;
415
416 if (actual == tbuf->count) {
417 if (debuglevel >= DEBUG_LEVEL_INFO)
418 printk("%s(%d)frame %p completed\n",
419 __FILE__,__LINE__,tbuf);
420
421 /* free current transmit buffer */
422 n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf);
Alexander Popov82f23412017-02-28 19:54:40 +0300423
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 /* wait up sleeping writers */
425 wake_up_interruptible(&tty->write_wait);
426
427 /* get next pending transmit buffer */
428 tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
429 } else {
430 if (debuglevel >= DEBUG_LEVEL_INFO)
431 printk("%s(%d)frame %p pending\n",
432 __FILE__,__LINE__,tbuf);
Alexander Popov82f23412017-02-28 19:54:40 +0300433
434 /*
435 * the buffer was not accepted by driver,
436 * return it back into tx queue
437 */
438 n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439 break;
440 }
441 }
442
443 if (!tbuf)
Ilya Zykov7962fce2011-11-07 11:32:46 +0400444 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445
446 /* Clear the re-entry flag */
447 spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
448 n_hdlc->tbusy = 0;
449 spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
450
451 if (n_hdlc->woke_up)
452 goto check_again;
453
454 if (debuglevel >= DEBUG_LEVEL_INFO)
455 printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__);
456
457} /* end of n_hdlc_send_frames() */
458
459/**
460 * n_hdlc_tty_wakeup - Callback for transmit wakeup
461 * @tty - pointer to associated tty instance data
462 *
463 * Called when low level device driver can accept more send data.
464 */
465static void n_hdlc_tty_wakeup(struct tty_struct *tty)
466{
467 struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
468
469 if (debuglevel >= DEBUG_LEVEL_INFO)
470 printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__);
471
472 if (!n_hdlc)
473 return;
474
475 if (tty != n_hdlc->tty) {
Ilya Zykov7962fce2011-11-07 11:32:46 +0400476 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 return;
478 }
479
480 n_hdlc_send_frames (n_hdlc, tty);
481
482} /* end of n_hdlc_tty_wakeup() */
483
484/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485 * n_hdlc_tty_receive - Called by tty driver when receive data is available
486 * @tty - pointer to tty instance data
487 * @data - pointer to received data
488 * @flags - pointer to flags for data
489 * @count - count of received data in bytes
490 *
491 * Called by tty low level driver when receive data is available. Data is
492 * interpreted as one HDLC frame.
493 */
Linus Torvalds55db4c62011-06-04 06:33:24 +0900494static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data,
495 char *flags, int count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496{
497 register struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
498 register struct n_hdlc_buf *buf;
499
500 if (debuglevel >= DEBUG_LEVEL_INFO)
501 printk("%s(%d)n_hdlc_tty_receive() called count=%d\n",
502 __FILE__,__LINE__, count);
503
504 /* This can happen if stuff comes in on the backup tty */
Harvey Harrisona01e0352008-04-28 16:50:04 -0700505 if (!n_hdlc || tty != n_hdlc->tty)
Linus Torvalds55db4c62011-06-04 06:33:24 +0900506 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507
508 /* verify line is using HDLC discipline */
509 if (n_hdlc->magic != HDLC_MAGIC) {
510 printk("%s(%d) line not using HDLC discipline\n",
511 __FILE__,__LINE__);
Linus Torvalds55db4c62011-06-04 06:33:24 +0900512 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 }
514
515 if ( count>maxframe ) {
516 if (debuglevel >= DEBUG_LEVEL_INFO)
517 printk("%s(%d) rx count>maxframesize, data discarded\n",
518 __FILE__,__LINE__);
Linus Torvalds55db4c62011-06-04 06:33:24 +0900519 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520 }
521
522 /* get a free HDLC buffer */
523 buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
524 if (!buf) {
525 /* no buffers in free list, attempt to allocate another rx buffer */
526 /* unless the maximum count has been reached */
527 if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT)
528 buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC);
529 }
530
531 if (!buf) {
532 if (debuglevel >= DEBUG_LEVEL_INFO)
533 printk("%s(%d) no more rx buffers, data discarded\n",
534 __FILE__,__LINE__);
Linus Torvalds55db4c62011-06-04 06:33:24 +0900535 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 }
537
538 /* copy received data to HDLC buffer */
539 memcpy(buf->buf,data,count);
540 buf->count=count;
541
542 /* add HDLC buffer to list of received frames */
543 n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf);
544
545 /* wake up any blocked reads and perform async signalling */
546 wake_up_interruptible (&tty->read_wait);
547 if (n_hdlc->tty->fasync != NULL)
548 kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN);
549
550} /* end of n_hdlc_tty_receive() */
551
552/**
Matt Mackall4a4efbd2006-01-03 13:27:11 +0100553 * n_hdlc_tty_read - Called to retrieve one frame of data (if available)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 * @tty - pointer to tty instance data
555 * @file - pointer to open file object
556 * @buf - pointer to returned data buffer
557 * @nr - size of returned data buffer
558 *
559 * Returns the number of bytes returned or error code.
560 */
561static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
562 __u8 __user *buf, size_t nr)
563{
564 struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
Paul Fulghum1035b632011-01-18 14:03:25 -0800565 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 struct n_hdlc_buf *rbuf;
Paul Fulghum1035b632011-01-18 14:03:25 -0800567 DECLARE_WAITQUEUE(wait, current);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568
569 if (debuglevel >= DEBUG_LEVEL_INFO)
570 printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__);
571
572 /* Validate the pointers */
573 if (!n_hdlc)
574 return -EIO;
575
576 /* verify user access to buffer */
577 if (!access_ok(VERIFY_WRITE, buf, nr)) {
578 printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user "
579 "buffer\n", __FILE__, __LINE__);
580 return -EFAULT;
581 }
582
Paul Fulghum1035b632011-01-18 14:03:25 -0800583 add_wait_queue(&tty->read_wait, &wait);
Alan Cox04f378b2008-04-30 00:53:29 -0700584
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585 for (;;) {
Brian Bloniarz0f40fbb2016-03-06 13:16:30 -0800586 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
Paul Fulghum1035b632011-01-18 14:03:25 -0800587 ret = -EIO;
588 break;
Alan Cox04f378b2008-04-30 00:53:29 -0700589 }
Paul Fulghum1035b632011-01-18 14:03:25 -0800590 if (tty_hung_up_p(file))
591 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592
Paul Fulghum1035b632011-01-18 14:03:25 -0800593 set_current_state(TASK_INTERRUPTIBLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594
595 rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
Paul Fulghum1035b632011-01-18 14:03:25 -0800596 if (rbuf) {
597 if (rbuf->count > nr) {
598 /* too large for caller's buffer */
599 ret = -EOVERFLOW;
600 } else {
601 if (copy_to_user(buf, rbuf->buf, rbuf->count))
602 ret = -EFAULT;
603 else
604 ret = rbuf->count;
605 }
606
607 if (n_hdlc->rx_free_buf_list.count >
608 DEFAULT_RX_BUF_COUNT)
609 kfree(rbuf);
610 else
611 n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612 break;
Paul Fulghum1035b632011-01-18 14:03:25 -0800613 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614
615 /* no data */
Alan Cox04f378b2008-04-30 00:53:29 -0700616 if (file->f_flags & O_NONBLOCK) {
Paul Fulghum1035b632011-01-18 14:03:25 -0800617 ret = -EAGAIN;
618 break;
Alan Cox04f378b2008-04-30 00:53:29 -0700619 }
Paul Fulghum1035b632011-01-18 14:03:25 -0800620
621 schedule();
622
Alan Cox04f378b2008-04-30 00:53:29 -0700623 if (signal_pending(current)) {
Paul Fulghum1035b632011-01-18 14:03:25 -0800624 ret = -EINTR;
625 break;
Alan Cox04f378b2008-04-30 00:53:29 -0700626 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 }
Paul Fulghum1035b632011-01-18 14:03:25 -0800628
629 remove_wait_queue(&tty->read_wait, &wait);
630 __set_current_state(TASK_RUNNING);
631
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632 return ret;
633
634} /* end of n_hdlc_tty_read() */
635
636/**
637 * n_hdlc_tty_write - write a single frame of data to device
638 * @tty - pointer to associated tty device instance data
639 * @file - pointer to file object data
640 * @data - pointer to transmit data (one frame)
641 * @count - size of transmit frame in bytes
642 *
643 * Returns the number of bytes written (or error code).
644 */
645static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
646 const unsigned char *data, size_t count)
647{
648 struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
649 int error = 0;
650 DECLARE_WAITQUEUE(wait, current);
651 struct n_hdlc_buf *tbuf;
652
653 if (debuglevel >= DEBUG_LEVEL_INFO)
Alexey Dobriyan5b5e0922017-02-27 14:30:02 -0800654 printk("%s(%d)n_hdlc_tty_write() called count=%zd\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655 __FILE__,__LINE__,count);
656
657 /* Verify pointers */
658 if (!n_hdlc)
659 return -EIO;
660
661 if (n_hdlc->magic != HDLC_MAGIC)
662 return -EIO;
663
664 /* verify frame size */
665 if (count > maxframe ) {
666 if (debuglevel & DEBUG_LEVEL_INFO)
667 printk (KERN_WARNING
668 "n_hdlc_tty_write: truncating user packet "
669 "from %lu to %d\n", (unsigned long) count,
670 maxframe );
671 count = maxframe;
672 }
673
674 add_wait_queue(&tty->write_wait, &wait);
Paul Fulghum1035b632011-01-18 14:03:25 -0800675
676 for (;;) {
677 set_current_state(TASK_INTERRUPTIBLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678
Paul Fulghum1035b632011-01-18 14:03:25 -0800679 tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list);
680 if (tbuf)
681 break;
682
Paul Fulghumc72f5272008-07-22 11:21:19 +0100683 if (file->f_flags & O_NONBLOCK) {
684 error = -EAGAIN;
685 break;
686 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 schedule();
688
689 n_hdlc = tty2n_hdlc (tty);
690 if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC ||
691 tty != n_hdlc->tty) {
692 printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc);
693 error = -EIO;
694 break;
695 }
696
697 if (signal_pending(current)) {
698 error = -EINTR;
699 break;
700 }
701 }
702
Paul Fulghum1035b632011-01-18 14:03:25 -0800703 __set_current_state(TASK_RUNNING);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704 remove_wait_queue(&tty->write_wait, &wait);
705
706 if (!error) {
707 /* Retrieve the user's buffer */
708 memcpy(tbuf->buf, data, count);
709
710 /* Send the data */
711 tbuf->count = error = count;
712 n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf);
713 n_hdlc_send_frames(n_hdlc,tty);
714 }
Paul Fulghum1035b632011-01-18 14:03:25 -0800715
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716 return error;
717
718} /* end of n_hdlc_tty_write() */
719
720/**
721 * n_hdlc_tty_ioctl - process IOCTL system call for the tty device.
722 * @tty - pointer to tty instance data
723 * @file - pointer to open file object for device
724 * @cmd - IOCTL command code
725 * @arg - argument for IOCTL call (cmd dependent)
726 *
727 * Returns command dependent result.
728 */
729static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
730 unsigned int cmd, unsigned long arg)
731{
732 struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
733 int error = 0;
734 int count;
735 unsigned long flags;
Alexander Popov82f23412017-02-28 19:54:40 +0300736 struct n_hdlc_buf *buf = NULL;
737
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738 if (debuglevel >= DEBUG_LEVEL_INFO)
739 printk("%s(%d)n_hdlc_tty_ioctl() called %d\n",
740 __FILE__,__LINE__,cmd);
741
742 /* Verify the status of the device */
743 if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC)
744 return -EBADF;
745
746 switch (cmd) {
747 case FIONREAD:
748 /* report count of read data available */
749 /* in next available frame (if any) */
750 spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags);
Alexander Popov82f23412017-02-28 19:54:40 +0300751 buf = list_first_entry_or_null(&n_hdlc->rx_buf_list.list,
752 struct n_hdlc_buf, list_item);
753 if (buf)
754 count = buf->count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755 else
756 count = 0;
757 spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags);
758 error = put_user(count, (int __user *)arg);
759 break;
760
761 case TIOCOUTQ:
762 /* get the pending tx byte count in the driver */
Alan Coxf34d7a52008-04-30 00:54:13 -0700763 count = tty_chars_in_buffer(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 /* add size of next output frame in queue */
765 spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags);
Alexander Popov82f23412017-02-28 19:54:40 +0300766 buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list,
767 struct n_hdlc_buf, list_item);
768 if (buf)
769 count += buf->count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags);
771 error = put_user(count, (int __user *)arg);
772 break;
773
Paul Fulghumbe10eb72009-06-22 18:42:56 +0100774 case TCFLSH:
775 switch (arg) {
776 case TCIOFLUSH:
777 case TCOFLUSH:
778 flush_tx_queue(tty);
779 }
780 /* fall through to default */
781
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 default:
Alan Cox47afa7a2008-10-13 10:44:17 +0100783 error = n_tty_ioctl_helper(tty, file, cmd, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 break;
785 }
786 return error;
787
788} /* end of n_hdlc_tty_ioctl() */
789
790/**
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
795 *
796 * Determine which operations (read/write) will not block and return info
797 * to caller.
798 * Returns a bit mask containing info on which ops will not block.
799 */
800static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
801 poll_table *wait)
802{
803 struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
804 unsigned int mask = 0;
805
806 if (debuglevel >= DEBUG_LEVEL_INFO)
807 printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__);
808
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) */
812
813 poll_wait(filp, &tty->read_wait, wait);
814 poll_wait(filp, &tty->write_wait, wait);
815
816 /* set bits for operations that won't block */
Alexander Popov82f23412017-02-28 19:54:40 +0300817 if (!list_empty(&n_hdlc->rx_buf_list.list))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818 mask |= POLLIN | POLLRDNORM; /* readable */
Brian Bloniarz0f40fbb2016-03-06 13:16:30 -0800819 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820 mask |= POLLHUP;
Alan Cox9c1729d2007-07-15 23:39:43 -0700821 if (tty_hung_up_p(filp))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 mask |= POLLHUP;
Alan Cox9c1729d2007-07-15 23:39:43 -0700823 if (!tty_is_writelocked(tty) &&
Alexander Popov82f23412017-02-28 19:54:40 +0300824 !list_empty(&n_hdlc->tx_free_buf_list.list))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825 mask |= POLLOUT | POLLWRNORM; /* writable */
826 }
827 return mask;
828} /* end of n_hdlc_tty_poll() */
829
830/**
831 * n_hdlc_alloc - allocate an n_hdlc instance data structure
832 *
833 * Returns a pointer to newly created structure if success, otherwise %NULL
834 */
835static struct n_hdlc *n_hdlc_alloc(void)
836{
837 struct n_hdlc_buf *buf;
838 int i;
Fabian Frederick8e25f8c2014-05-26 21:32:42 +0200839 struct n_hdlc *n_hdlc = kzalloc(sizeof(*n_hdlc), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840
841 if (!n_hdlc)
842 return NULL;
843
Jiri Slabye9b736d2015-11-26 19:28:26 +0100844 spin_lock_init(&n_hdlc->rx_free_buf_list.spinlock);
845 spin_lock_init(&n_hdlc->tx_free_buf_list.spinlock);
846 spin_lock_init(&n_hdlc->rx_buf_list.spinlock);
847 spin_lock_init(&n_hdlc->tx_buf_list.spinlock);
Alexander Popov82f23412017-02-28 19:54:40 +0300848
849 INIT_LIST_HEAD(&n_hdlc->rx_free_buf_list.list);
850 INIT_LIST_HEAD(&n_hdlc->tx_free_buf_list.list);
851 INIT_LIST_HEAD(&n_hdlc->rx_buf_list.list);
852 INIT_LIST_HEAD(&n_hdlc->tx_buf_list.list);
853
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854 /* allocate free rx buffer list */
855 for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) {
856 buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL);
857 if (buf)
858 n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf);
859 else if (debuglevel >= DEBUG_LEVEL_INFO)
860 printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i);
861 }
862
863 /* allocate free tx buffer list */
864 for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) {
865 buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL);
866 if (buf)
867 n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf);
868 else if (debuglevel >= DEBUG_LEVEL_INFO)
869 printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i);
870 }
871
872 /* Initialize the control block */
873 n_hdlc->magic = HDLC_MAGIC;
874 n_hdlc->flags = 0;
875
876 return n_hdlc;
877
878} /* end of n_hdlc_alloc() */
879
880/**
Alexander Popov82f23412017-02-28 19:54:40 +0300881 * n_hdlc_buf_return - put the HDLC buffer after the head of the specified list
882 * @buf_list - pointer to the buffer list
883 * @buf - pointer to the buffer
884 */
885static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list,
886 struct n_hdlc_buf *buf)
887{
888 unsigned long flags;
889
890 spin_lock_irqsave(&buf_list->spinlock, flags);
891
892 list_add(&buf->list_item, &buf_list->list);
893 buf_list->count++;
894
895 spin_unlock_irqrestore(&buf_list->spinlock, flags);
896}
897
898/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899 * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list
Alexander Popov82f23412017-02-28 19:54:40 +0300900 * @buf_list - pointer to buffer list
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 * @buf - pointer to buffer
902 */
Alexander Popov82f23412017-02-28 19:54:40 +0300903static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 struct n_hdlc_buf *buf)
905{
906 unsigned long flags;
Alexander Popov82f23412017-02-28 19:54:40 +0300907
908 spin_lock_irqsave(&buf_list->spinlock, flags);
909
910 list_add_tail(&buf->list_item, &buf_list->list);
911 buf_list->count++;
912
913 spin_unlock_irqrestore(&buf_list->spinlock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914} /* end of n_hdlc_buf_put() */
915
916/**
917 * n_hdlc_buf_get - remove and return an HDLC buffer from list
Alexander Popov82f23412017-02-28 19:54:40 +0300918 * @buf_list - pointer to HDLC buffer list
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919 *
920 * Remove and return an HDLC buffer from the head of the specified HDLC buffer
921 * list.
922 * Returns a pointer to HDLC buffer if available, otherwise %NULL.
923 */
Alexander Popov82f23412017-02-28 19:54:40 +0300924static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925{
926 unsigned long flags;
927 struct n_hdlc_buf *buf;
Alexander Popov82f23412017-02-28 19:54:40 +0300928
929 spin_lock_irqsave(&buf_list->spinlock, flags);
930
931 buf = list_first_entry_or_null(&buf_list->list,
932 struct n_hdlc_buf, list_item);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933 if (buf) {
Alexander Popov82f23412017-02-28 19:54:40 +0300934 list_del(&buf->list_item);
935 buf_list->count--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936 }
Alexander Popov82f23412017-02-28 19:54:40 +0300937
938 spin_unlock_irqrestore(&buf_list->spinlock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700939 return buf;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700940} /* end of n_hdlc_buf_get() */
941
Kees Cook06324662017-05-08 15:59:05 -0700942static const char hdlc_banner[] __initconst =
Paul Fulghumbe10eb72009-06-22 18:42:56 +0100943 KERN_INFO "HDLC line discipline maxframe=%u\n";
Kees Cook06324662017-05-08 15:59:05 -0700944static const char hdlc_register_ok[] __initconst =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700945 KERN_INFO "N_HDLC line discipline registered.\n";
Kees Cook06324662017-05-08 15:59:05 -0700946static const char hdlc_register_fail[] __initconst =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947 KERN_ERR "error registering line discipline: %d\n";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948
949static int __init n_hdlc_init(void)
950{
951 int status;
952
953 /* range check maxframe arg */
954 if (maxframe < 4096)
955 maxframe = 4096;
956 else if (maxframe > 65535)
957 maxframe = 65535;
958
959 printk(hdlc_banner, maxframe);
960
961 status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc);
962 if (!status)
963 printk(hdlc_register_ok);
964 else
965 printk(hdlc_register_fail, status);
966
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967 return status;
968
969} /* end of init_module() */
970
Kees Cook06324662017-05-08 15:59:05 -0700971static const char hdlc_unregister_ok[] __exitdata =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972 KERN_INFO "N_HDLC: line discipline unregistered\n";
Kees Cook06324662017-05-08 15:59:05 -0700973static const char hdlc_unregister_fail[] __exitdata =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n";
975
976static void __exit n_hdlc_exit(void)
977{
978 /* Release tty registration of line discipline */
Alexey Dobriyan64ccd712005-06-23 00:10:33 -0700979 int status = tty_unregister_ldisc(N_HDLC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980
981 if (status)
982 printk(hdlc_unregister_fail, status);
983 else
984 printk(hdlc_unregister_ok);
985}
986
987module_init(n_hdlc_init);
988module_exit(n_hdlc_exit);
989
990MODULE_LICENSE("GPL");
991MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com");
992module_param(debuglevel, int, 0);
993module_param(maxframe, int, 0);
994MODULE_ALIAS_LDISC(N_HDLC);