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e3b3d0f5 | 1 | // SPDX-License-Identifier: GPL-1.0+ |
1da177e4 LT |
2 | /* generic HDLC line discipline for Linux |
3 | * | |
4 | * Written by Paul Fulghum paulkf@microgate.com | |
5 | * for Microgate Corporation | |
6 | * | |
7 | * Microgate and SyncLink are registered trademarks of Microgate Corporation | |
8 | * | |
9 | * Adapted from ppp.c, written by Michael Callahan <callahan@maths.ox.ac.uk>, | |
10 | * Al Longyear <longyear@netcom.com>, | |
11 | * Paul Mackerras <Paul.Mackerras@cs.anu.edu.au> | |
12 | * | |
13 | * Original release 01/11/99 | |
1da177e4 LT |
14 | * |
15 | * This code is released under the GNU General Public License (GPL) | |
16 | * | |
17 | * This module implements the tty line discipline N_HDLC for use with | |
18 | * tty device drivers that support bit-synchronous HDLC communications. | |
19 | * | |
20 | * All HDLC data is frame oriented which means: | |
21 | * | |
22 | * 1. tty write calls represent one complete transmit frame of data | |
23 | * The device driver should accept the complete frame or none of | |
24 | * the frame (busy) in the write method. Each write call should have | |
25 | * a byte count in the range of 2-65535 bytes (2 is min HDLC frame | |
26 | * with 1 addr byte and 1 ctrl byte). The max byte count of 65535 | |
27 | * should include any crc bytes required. For example, when using | |
28 | * CCITT CRC32, 4 crc bytes are required, so the maximum size frame | |
29 | * the application may transmit is limited to 65531 bytes. For CCITT | |
30 | * CRC16, the maximum application frame size would be 65533. | |
31 | * | |
32 | * | |
33 | * 2. receive callbacks from the device driver represents | |
34 | * one received frame. The device driver should bypass | |
35 | * the tty flip buffer and call the line discipline receive | |
36 | * callback directly to avoid fragmenting or concatenating | |
37 | * multiple frames into a single receive callback. | |
38 | * | |
39 | * The HDLC line discipline queues the receive frames in separate | |
40 | * buffers so complete receive frames can be returned by the | |
41 | * tty read calls. | |
42 | * | |
43 | * 3. tty read calls returns an entire frame of data or nothing. | |
44 | * | |
45 | * 4. all send and receive data is considered raw. No processing | |
46 | * or translation is performed by the line discipline, regardless | |
47 | * of the tty flags | |
48 | * | |
49 | * 5. When line discipline is queried for the amount of receive | |
50 | * data available (FIOC), 0 is returned if no data available, | |
51 | * otherwise the count of the next available frame is returned. | |
52 | * (instead of the sum of all received frame counts). | |
53 | * | |
54 | * These conventions allow the standard tty programming interface | |
55 | * to be used for synchronous HDLC applications when used with | |
56 | * this line discipline (or another line discipline that is frame | |
57 | * oriented such as N_PPP). | |
58 | * | |
59 | * The SyncLink driver (synclink.c) implements both asynchronous | |
60 | * (using standard line discipline N_TTY) and synchronous HDLC | |
61 | * (using N_HDLC) communications, with the latter using the above | |
62 | * conventions. | |
63 | * | |
64 | * This implementation is very basic and does not maintain | |
65 | * any statistics. The main point is to enforce the raw data | |
66 | * and frame orientation of HDLC communications. | |
67 | * | |
68 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED | |
69 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
70 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | |
71 | * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, | |
72 | * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
73 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | |
74 | * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
75 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
76 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
77 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
78 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
79 | */ | |
80 | ||
81 | #define HDLC_MAGIC 0x239e | |
1da177e4 | 82 | |
1da177e4 LT |
83 | #include <linux/module.h> |
84 | #include <linux/init.h> | |
85 | #include <linux/kernel.h> | |
86 | #include <linux/sched.h> | |
87 | #include <linux/types.h> | |
88 | #include <linux/fcntl.h> | |
89 | #include <linux/interrupt.h> | |
90 | #include <linux/ptrace.h> | |
91 | ||
92 | #undef VERSION | |
93 | #define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch)) | |
94 | ||
95 | #include <linux/poll.h> | |
96 | #include <linux/in.h> | |
97 | #include <linux/ioctl.h> | |
98 | #include <linux/slab.h> | |
99 | #include <linux/tty.h> | |
100 | #include <linux/errno.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 | ||
1da177e4 | 106 | #include <asm/termios.h> |
7c0f6ba6 | 107 | #include <linux/uaccess.h> |
1da177e4 LT |
108 | |
109 | /* | |
110 | * Buffers for individual HDLC frames | |
111 | */ | |
112 | #define MAX_HDLC_FRAME_SIZE 65535 | |
113 | #define DEFAULT_RX_BUF_COUNT 10 | |
114 | #define MAX_RX_BUF_COUNT 60 | |
be10eb75 | 115 | #define DEFAULT_TX_BUF_COUNT 3 |
1da177e4 LT |
116 | |
117 | struct n_hdlc_buf { | |
82f2341c | 118 | struct list_head list_item; |
1da177e4 LT |
119 | int count; |
120 | char buf[1]; | |
121 | }; | |
122 | ||
123 | #define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe) | |
124 | ||
125 | struct n_hdlc_buf_list { | |
82f2341c | 126 | struct list_head list; |
1da177e4 LT |
127 | int count; |
128 | spinlock_t spinlock; | |
129 | }; | |
130 | ||
131 | /** | |
132 | * struct n_hdlc - per device instance data structure | |
133 | * @magic - magic value for structure | |
134 | * @flags - miscellaneous control flags | |
135 | * @tty - ptr to TTY structure | |
136 | * @backup_tty - TTY to use if tty gets closed | |
137 | * @tbusy - reentrancy flag for tx wakeup code | |
138 | * @woke_up - FIXME: describe this field | |
1da177e4 LT |
139 | * @tx_buf_list - list of pending transmit frame buffers |
140 | * @rx_buf_list - list of received frame buffers | |
141 | * @tx_free_buf_list - list unused transmit frame buffers | |
142 | * @rx_free_buf_list - list unused received frame buffers | |
143 | */ | |
144 | struct n_hdlc { | |
145 | int magic; | |
146 | __u32 flags; | |
147 | struct tty_struct *tty; | |
148 | struct tty_struct *backup_tty; | |
149 | int tbusy; | |
150 | int woke_up; | |
1da177e4 LT |
151 | struct n_hdlc_buf_list tx_buf_list; |
152 | struct n_hdlc_buf_list rx_buf_list; | |
153 | struct n_hdlc_buf_list tx_free_buf_list; | |
154 | struct n_hdlc_buf_list rx_free_buf_list; | |
155 | }; | |
156 | ||
157 | /* | |
158 | * HDLC buffer list manipulation functions | |
159 | */ | |
82f2341c AP |
160 | static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, |
161 | struct n_hdlc_buf *buf); | |
1da177e4 LT |
162 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, |
163 | struct n_hdlc_buf *buf); | |
164 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list); | |
165 | ||
166 | /* Local functions */ | |
167 | ||
168 | static struct n_hdlc *n_hdlc_alloc (void); | |
169 | ||
170 | /* debug level can be set by insmod for debugging purposes */ | |
171 | #define DEBUG_LEVEL_INFO 1 | |
172 | static int debuglevel; | |
173 | ||
174 | /* max frame size for memory allocations */ | |
175 | static int maxframe = 4096; | |
176 | ||
177 | /* TTY callbacks */ | |
178 | ||
179 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
180 | __u8 __user *buf, size_t nr); | |
181 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
182 | const unsigned char *buf, size_t nr); | |
183 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
184 | unsigned int cmd, unsigned long arg); | |
185 | static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, | |
186 | poll_table *wait); | |
187 | static int n_hdlc_tty_open(struct tty_struct *tty); | |
188 | static void n_hdlc_tty_close(struct tty_struct *tty); | |
55db4c64 LT |
189 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp, |
190 | char *fp, int count); | |
1da177e4 LT |
191 | static void n_hdlc_tty_wakeup(struct tty_struct *tty); |
192 | ||
193 | #define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f))) | |
194 | ||
195 | #define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data)) | |
196 | #define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty) | |
197 | ||
be10eb75 PF |
198 | static void flush_rx_queue(struct tty_struct *tty) |
199 | { | |
200 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
201 | struct n_hdlc_buf *buf; | |
202 | ||
203 | while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list))) | |
204 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf); | |
205 | } | |
206 | ||
207 | static void flush_tx_queue(struct tty_struct *tty) | |
208 | { | |
209 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
210 | struct n_hdlc_buf *buf; | |
be10eb75 PF |
211 | |
212 | while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list))) | |
213 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf); | |
be10eb75 PF |
214 | } |
215 | ||
a352def2 | 216 | static struct tty_ldisc_ops n_hdlc_ldisc = { |
1da177e4 LT |
217 | .owner = THIS_MODULE, |
218 | .magic = TTY_LDISC_MAGIC, | |
219 | .name = "hdlc", | |
220 | .open = n_hdlc_tty_open, | |
221 | .close = n_hdlc_tty_close, | |
222 | .read = n_hdlc_tty_read, | |
223 | .write = n_hdlc_tty_write, | |
224 | .ioctl = n_hdlc_tty_ioctl, | |
225 | .poll = n_hdlc_tty_poll, | |
226 | .receive_buf = n_hdlc_tty_receive, | |
1da177e4 | 227 | .write_wakeup = n_hdlc_tty_wakeup, |
be10eb75 | 228 | .flush_buffer = flush_rx_queue, |
1da177e4 LT |
229 | }; |
230 | ||
231 | /** | |
232 | * n_hdlc_release - release an n_hdlc per device line discipline info structure | |
233 | * @n_hdlc - per device line discipline info structure | |
234 | */ | |
235 | static void n_hdlc_release(struct n_hdlc *n_hdlc) | |
236 | { | |
237 | struct tty_struct *tty = n_hdlc2tty (n_hdlc); | |
238 | struct n_hdlc_buf *buf; | |
239 | ||
240 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
241 | printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__); | |
242 | ||
243 | /* Ensure that the n_hdlcd process is not hanging on select()/poll() */ | |
244 | wake_up_interruptible (&tty->read_wait); | |
245 | wake_up_interruptible (&tty->write_wait); | |
246 | ||
827afdf0 | 247 | if (tty->disc_data == n_hdlc) |
1da177e4 LT |
248 | tty->disc_data = NULL; /* Break the tty->n_hdlc link */ |
249 | ||
250 | /* Release transmit and receive buffers */ | |
251 | for(;;) { | |
252 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
253 | if (buf) { | |
254 | kfree(buf); | |
255 | } else | |
256 | break; | |
257 | } | |
258 | for(;;) { | |
259 | buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); | |
260 | if (buf) { | |
261 | kfree(buf); | |
262 | } else | |
263 | break; | |
264 | } | |
265 | for(;;) { | |
266 | buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
267 | if (buf) { | |
268 | kfree(buf); | |
269 | } else | |
270 | break; | |
271 | } | |
272 | for(;;) { | |
273 | buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
274 | if (buf) { | |
275 | kfree(buf); | |
276 | } else | |
277 | break; | |
278 | } | |
1da177e4 LT |
279 | kfree(n_hdlc); |
280 | ||
281 | } /* end of n_hdlc_release() */ | |
282 | ||
283 | /** | |
284 | * n_hdlc_tty_close - line discipline close | |
285 | * @tty - pointer to tty info structure | |
286 | * | |
287 | * Called when the line discipline is changed to something | |
288 | * else, the tty is closed, or the tty detects a hangup. | |
289 | */ | |
290 | static void n_hdlc_tty_close(struct tty_struct *tty) | |
291 | { | |
292 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
293 | ||
294 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
295 | printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__); | |
296 | ||
297 | if (n_hdlc != NULL) { | |
298 | if (n_hdlc->magic != HDLC_MAGIC) { | |
299 | printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n"); | |
300 | return; | |
301 | } | |
302 | #if defined(TTY_NO_WRITE_SPLIT) | |
303 | clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
304 | #endif | |
305 | tty->disc_data = NULL; | |
306 | if (tty == n_hdlc->backup_tty) | |
307 | n_hdlc->backup_tty = NULL; | |
308 | if (tty != n_hdlc->tty) | |
309 | return; | |
310 | if (n_hdlc->backup_tty) { | |
311 | n_hdlc->tty = n_hdlc->backup_tty; | |
312 | } else { | |
313 | n_hdlc_release (n_hdlc); | |
314 | } | |
315 | } | |
316 | ||
317 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
318 | printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__); | |
319 | ||
320 | } /* end of n_hdlc_tty_close() */ | |
321 | ||
322 | /** | |
323 | * n_hdlc_tty_open - called when line discipline changed to n_hdlc | |
324 | * @tty - pointer to tty info structure | |
325 | * | |
326 | * Returns 0 if success, otherwise error code | |
327 | */ | |
328 | static int n_hdlc_tty_open (struct tty_struct *tty) | |
329 | { | |
330 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
331 | ||
332 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
333 | printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n", | |
334 | __FILE__,__LINE__, | |
335 | tty->name); | |
336 | ||
337 | /* There should not be an existing table for this slot. */ | |
338 | if (n_hdlc) { | |
339 | printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" ); | |
340 | return -EEXIST; | |
341 | } | |
342 | ||
343 | n_hdlc = n_hdlc_alloc(); | |
344 | if (!n_hdlc) { | |
345 | printk (KERN_ERR "n_hdlc_alloc failed\n"); | |
346 | return -ENFILE; | |
347 | } | |
348 | ||
349 | tty->disc_data = n_hdlc; | |
350 | n_hdlc->tty = tty; | |
33f0f88f | 351 | tty->receive_room = 65536; |
1da177e4 LT |
352 | |
353 | #if defined(TTY_NO_WRITE_SPLIT) | |
354 | /* change tty_io write() to not split large writes into 8K chunks */ | |
355 | set_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
356 | #endif | |
357 | ||
be10eb75 | 358 | /* flush receive data from driver */ |
f34d7a5b | 359 | tty_driver_flush_buffer(tty); |
1da177e4 LT |
360 | |
361 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
362 | printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__); | |
363 | ||
364 | return 0; | |
365 | ||
366 | } /* end of n_tty_hdlc_open() */ | |
367 | ||
368 | /** | |
369 | * n_hdlc_send_frames - send frames on pending send buffer list | |
370 | * @n_hdlc - pointer to ldisc instance data | |
371 | * @tty - pointer to tty instance data | |
372 | * | |
373 | * Send frames on pending send buffer list until the driver does not accept a | |
374 | * frame (busy) this function is called after adding a frame to the send buffer | |
375 | * list and by the tty wakeup callback. | |
376 | */ | |
377 | static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) | |
378 | { | |
379 | register int actual; | |
380 | unsigned long flags; | |
381 | struct n_hdlc_buf *tbuf; | |
382 | ||
383 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
384 | printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__); | |
385 | check_again: | |
386 | ||
387 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
388 | if (n_hdlc->tbusy) { | |
389 | n_hdlc->woke_up = 1; | |
390 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
391 | return; | |
392 | } | |
393 | n_hdlc->tbusy = 1; | |
394 | n_hdlc->woke_up = 0; | |
395 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
396 | ||
82f2341c | 397 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); |
1da177e4 LT |
398 | while (tbuf) { |
399 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
400 | printk("%s(%d)sending frame %p, count=%d\n", | |
401 | __FILE__,__LINE__,tbuf,tbuf->count); | |
402 | ||
403 | /* Send the next block of data to device */ | |
7962fce9 | 404 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
f34d7a5b | 405 | actual = tty->ops->write(tty, tbuf->buf, tbuf->count); |
b0fed314 JS |
406 | |
407 | /* rollback was possible and has been done */ | |
408 | if (actual == -ERESTARTSYS) { | |
82f2341c | 409 | n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); |
b0fed314 JS |
410 | break; |
411 | } | |
1da177e4 LT |
412 | /* if transmit error, throw frame away by */ |
413 | /* pretending it was accepted by driver */ | |
414 | if (actual < 0) | |
415 | actual = tbuf->count; | |
416 | ||
417 | if (actual == tbuf->count) { | |
418 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
419 | printk("%s(%d)frame %p completed\n", | |
420 | __FILE__,__LINE__,tbuf); | |
421 | ||
422 | /* free current transmit buffer */ | |
423 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf); | |
82f2341c | 424 | |
1da177e4 LT |
425 | /* wait up sleeping writers */ |
426 | wake_up_interruptible(&tty->write_wait); | |
427 | ||
428 | /* get next pending transmit buffer */ | |
429 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
430 | } else { | |
431 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
432 | printk("%s(%d)frame %p pending\n", | |
433 | __FILE__,__LINE__,tbuf); | |
82f2341c AP |
434 | |
435 | /* | |
436 | * the buffer was not accepted by driver, | |
437 | * return it back into tx queue | |
438 | */ | |
439 | n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); | |
1da177e4 LT |
440 | break; |
441 | } | |
442 | } | |
443 | ||
444 | if (!tbuf) | |
7962fce9 | 445 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
1da177e4 LT |
446 | |
447 | /* Clear the re-entry flag */ | |
448 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
449 | n_hdlc->tbusy = 0; | |
450 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
451 | ||
452 | if (n_hdlc->woke_up) | |
453 | goto check_again; | |
454 | ||
455 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
456 | printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__); | |
457 | ||
458 | } /* end of n_hdlc_send_frames() */ | |
459 | ||
460 | /** | |
461 | * n_hdlc_tty_wakeup - Callback for transmit wakeup | |
462 | * @tty - pointer to associated tty instance data | |
463 | * | |
464 | * Called when low level device driver can accept more send data. | |
465 | */ | |
466 | static void n_hdlc_tty_wakeup(struct tty_struct *tty) | |
467 | { | |
468 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
469 | ||
470 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
471 | printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__); | |
472 | ||
473 | if (!n_hdlc) | |
474 | return; | |
475 | ||
476 | if (tty != n_hdlc->tty) { | |
7962fce9 | 477 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
1da177e4 LT |
478 | return; |
479 | } | |
480 | ||
481 | n_hdlc_send_frames (n_hdlc, tty); | |
482 | ||
483 | } /* end of n_hdlc_tty_wakeup() */ | |
484 | ||
1da177e4 LT |
485 | /** |
486 | * n_hdlc_tty_receive - Called by tty driver when receive data is available | |
487 | * @tty - pointer to tty instance data | |
488 | * @data - pointer to received data | |
489 | * @flags - pointer to flags for data | |
490 | * @count - count of received data in bytes | |
491 | * | |
492 | * Called by tty low level driver when receive data is available. Data is | |
493 | * interpreted as one HDLC frame. | |
494 | */ | |
55db4c64 LT |
495 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data, |
496 | char *flags, int count) | |
1da177e4 LT |
497 | { |
498 | register struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
499 | register struct n_hdlc_buf *buf; | |
500 | ||
501 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
502 | printk("%s(%d)n_hdlc_tty_receive() called count=%d\n", | |
503 | __FILE__,__LINE__, count); | |
504 | ||
505 | /* This can happen if stuff comes in on the backup tty */ | |
a01e035e | 506 | if (!n_hdlc || tty != n_hdlc->tty) |
55db4c64 | 507 | return; |
1da177e4 LT |
508 | |
509 | /* verify line is using HDLC discipline */ | |
510 | if (n_hdlc->magic != HDLC_MAGIC) { | |
511 | printk("%s(%d) line not using HDLC discipline\n", | |
512 | __FILE__,__LINE__); | |
55db4c64 | 513 | return; |
1da177e4 LT |
514 | } |
515 | ||
516 | if ( count>maxframe ) { | |
517 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
518 | printk("%s(%d) rx count>maxframesize, data discarded\n", | |
519 | __FILE__,__LINE__); | |
55db4c64 | 520 | return; |
1da177e4 LT |
521 | } |
522 | ||
523 | /* get a free HDLC buffer */ | |
524 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
525 | if (!buf) { | |
526 | /* no buffers in free list, attempt to allocate another rx buffer */ | |
527 | /* unless the maximum count has been reached */ | |
528 | if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT) | |
529 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC); | |
530 | } | |
531 | ||
532 | if (!buf) { | |
533 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
534 | printk("%s(%d) no more rx buffers, data discarded\n", | |
535 | __FILE__,__LINE__); | |
55db4c64 | 536 | return; |
1da177e4 LT |
537 | } |
538 | ||
539 | /* copy received data to HDLC buffer */ | |
540 | memcpy(buf->buf,data,count); | |
541 | buf->count=count; | |
542 | ||
543 | /* add HDLC buffer to list of received frames */ | |
544 | n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf); | |
545 | ||
546 | /* wake up any blocked reads and perform async signalling */ | |
547 | wake_up_interruptible (&tty->read_wait); | |
548 | if (n_hdlc->tty->fasync != NULL) | |
549 | kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN); | |
550 | ||
551 | } /* end of n_hdlc_tty_receive() */ | |
552 | ||
553 | /** | |
4a4efbde | 554 | * n_hdlc_tty_read - Called to retrieve one frame of data (if available) |
1da177e4 LT |
555 | * @tty - pointer to tty instance data |
556 | * @file - pointer to open file object | |
557 | * @buf - pointer to returned data buffer | |
558 | * @nr - size of returned data buffer | |
559 | * | |
560 | * Returns the number of bytes returned or error code. | |
561 | */ | |
562 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
563 | __u8 __user *buf, size_t nr) | |
564 | { | |
565 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
1035b63d | 566 | int ret = 0; |
1da177e4 | 567 | struct n_hdlc_buf *rbuf; |
1035b63d | 568 | DECLARE_WAITQUEUE(wait, current); |
1da177e4 LT |
569 | |
570 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
571 | printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__); | |
572 | ||
573 | /* Validate the pointers */ | |
574 | if (!n_hdlc) | |
575 | return -EIO; | |
576 | ||
577 | /* verify user access to buffer */ | |
578 | if (!access_ok(VERIFY_WRITE, buf, nr)) { | |
579 | printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user " | |
580 | "buffer\n", __FILE__, __LINE__); | |
581 | return -EFAULT; | |
582 | } | |
583 | ||
1035b63d | 584 | add_wait_queue(&tty->read_wait, &wait); |
04f378b1 | 585 | |
1da177e4 | 586 | for (;;) { |
0f40fbbc | 587 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { |
1035b63d PF |
588 | ret = -EIO; |
589 | break; | |
04f378b1 | 590 | } |
1035b63d PF |
591 | if (tty_hung_up_p(file)) |
592 | break; | |
1da177e4 | 593 | |
1035b63d | 594 | set_current_state(TASK_INTERRUPTIBLE); |
1da177e4 LT |
595 | |
596 | rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
1035b63d PF |
597 | if (rbuf) { |
598 | if (rbuf->count > nr) { | |
599 | /* too large for caller's buffer */ | |
600 | ret = -EOVERFLOW; | |
601 | } else { | |
602 | if (copy_to_user(buf, rbuf->buf, rbuf->count)) | |
603 | ret = -EFAULT; | |
604 | else | |
605 | ret = rbuf->count; | |
606 | } | |
607 | ||
608 | if (n_hdlc->rx_free_buf_list.count > | |
609 | DEFAULT_RX_BUF_COUNT) | |
610 | kfree(rbuf); | |
611 | else | |
612 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf); | |
1da177e4 | 613 | break; |
1035b63d | 614 | } |
1da177e4 LT |
615 | |
616 | /* no data */ | |
04f378b1 | 617 | if (file->f_flags & O_NONBLOCK) { |
1035b63d PF |
618 | ret = -EAGAIN; |
619 | break; | |
04f378b1 | 620 | } |
1035b63d PF |
621 | |
622 | schedule(); | |
623 | ||
04f378b1 | 624 | if (signal_pending(current)) { |
1035b63d PF |
625 | ret = -EINTR; |
626 | break; | |
04f378b1 | 627 | } |
1da177e4 | 628 | } |
1035b63d PF |
629 | |
630 | remove_wait_queue(&tty->read_wait, &wait); | |
631 | __set_current_state(TASK_RUNNING); | |
632 | ||
1da177e4 LT |
633 | return ret; |
634 | ||
635 | } /* end of n_hdlc_tty_read() */ | |
636 | ||
637 | /** | |
638 | * n_hdlc_tty_write - write a single frame of data to device | |
639 | * @tty - pointer to associated tty device instance data | |
640 | * @file - pointer to file object data | |
641 | * @data - pointer to transmit data (one frame) | |
642 | * @count - size of transmit frame in bytes | |
643 | * | |
644 | * Returns the number of bytes written (or error code). | |
645 | */ | |
646 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
647 | const unsigned char *data, size_t count) | |
648 | { | |
649 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
650 | int error = 0; | |
651 | DECLARE_WAITQUEUE(wait, current); | |
652 | struct n_hdlc_buf *tbuf; | |
653 | ||
654 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
5b5e0928 | 655 | printk("%s(%d)n_hdlc_tty_write() called count=%zd\n", |
1da177e4 LT |
656 | __FILE__,__LINE__,count); |
657 | ||
658 | /* Verify pointers */ | |
659 | if (!n_hdlc) | |
660 | return -EIO; | |
661 | ||
662 | if (n_hdlc->magic != HDLC_MAGIC) | |
663 | return -EIO; | |
664 | ||
665 | /* verify frame size */ | |
666 | if (count > maxframe ) { | |
667 | if (debuglevel & DEBUG_LEVEL_INFO) | |
668 | printk (KERN_WARNING | |
669 | "n_hdlc_tty_write: truncating user packet " | |
670 | "from %lu to %d\n", (unsigned long) count, | |
671 | maxframe ); | |
672 | count = maxframe; | |
673 | } | |
674 | ||
675 | add_wait_queue(&tty->write_wait, &wait); | |
1035b63d PF |
676 | |
677 | for (;;) { | |
678 | set_current_state(TASK_INTERRUPTIBLE); | |
1da177e4 | 679 | |
1035b63d PF |
680 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); |
681 | if (tbuf) | |
682 | break; | |
683 | ||
c72f527c PF |
684 | if (file->f_flags & O_NONBLOCK) { |
685 | error = -EAGAIN; | |
686 | break; | |
687 | } | |
1da177e4 LT |
688 | schedule(); |
689 | ||
690 | n_hdlc = tty2n_hdlc (tty); | |
691 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || | |
692 | tty != n_hdlc->tty) { | |
693 | printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc); | |
694 | error = -EIO; | |
695 | break; | |
696 | } | |
697 | ||
698 | if (signal_pending(current)) { | |
699 | error = -EINTR; | |
700 | break; | |
701 | } | |
702 | } | |
703 | ||
1035b63d | 704 | __set_current_state(TASK_RUNNING); |
1da177e4 LT |
705 | remove_wait_queue(&tty->write_wait, &wait); |
706 | ||
707 | if (!error) { | |
708 | /* Retrieve the user's buffer */ | |
709 | memcpy(tbuf->buf, data, count); | |
710 | ||
711 | /* Send the data */ | |
712 | tbuf->count = error = count; | |
713 | n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf); | |
714 | n_hdlc_send_frames(n_hdlc,tty); | |
715 | } | |
1035b63d | 716 | |
1da177e4 LT |
717 | return error; |
718 | ||
719 | } /* end of n_hdlc_tty_write() */ | |
720 | ||
721 | /** | |
722 | * n_hdlc_tty_ioctl - process IOCTL system call for the tty device. | |
723 | * @tty - pointer to tty instance data | |
724 | * @file - pointer to open file object for device | |
725 | * @cmd - IOCTL command code | |
726 | * @arg - argument for IOCTL call (cmd dependent) | |
727 | * | |
728 | * Returns command dependent result. | |
729 | */ | |
730 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
731 | unsigned int cmd, unsigned long arg) | |
732 | { | |
733 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
734 | int error = 0; | |
735 | int count; | |
736 | unsigned long flags; | |
82f2341c AP |
737 | struct n_hdlc_buf *buf = NULL; |
738 | ||
1da177e4 LT |
739 | if (debuglevel >= DEBUG_LEVEL_INFO) |
740 | printk("%s(%d)n_hdlc_tty_ioctl() called %d\n", | |
741 | __FILE__,__LINE__,cmd); | |
742 | ||
743 | /* Verify the status of the device */ | |
744 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC) | |
745 | return -EBADF; | |
746 | ||
747 | switch (cmd) { | |
748 | case FIONREAD: | |
749 | /* report count of read data available */ | |
750 | /* in next available frame (if any) */ | |
751 | spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags); | |
82f2341c AP |
752 | buf = list_first_entry_or_null(&n_hdlc->rx_buf_list.list, |
753 | struct n_hdlc_buf, list_item); | |
754 | if (buf) | |
755 | count = buf->count; | |
1da177e4 LT |
756 | else |
757 | count = 0; | |
758 | spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags); | |
759 | error = put_user(count, (int __user *)arg); | |
760 | break; | |
761 | ||
762 | case TIOCOUTQ: | |
763 | /* get the pending tx byte count in the driver */ | |
f34d7a5b | 764 | count = tty_chars_in_buffer(tty); |
1da177e4 LT |
765 | /* add size of next output frame in queue */ |
766 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags); | |
82f2341c AP |
767 | buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list, |
768 | struct n_hdlc_buf, list_item); | |
769 | if (buf) | |
770 | count += buf->count; | |
1da177e4 LT |
771 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags); |
772 | error = put_user(count, (int __user *)arg); | |
773 | break; | |
774 | ||
be10eb75 PF |
775 | case TCFLSH: |
776 | switch (arg) { | |
777 | case TCIOFLUSH: | |
778 | case TCOFLUSH: | |
779 | flush_tx_queue(tty); | |
780 | } | |
781 | /* fall through to default */ | |
782 | ||
1da177e4 | 783 | default: |
47afa7a5 | 784 | error = n_tty_ioctl_helper(tty, file, cmd, arg); |
1da177e4 LT |
785 | break; |
786 | } | |
787 | return error; | |
788 | ||
789 | } /* end of n_hdlc_tty_ioctl() */ | |
790 | ||
791 | /** | |
792 | * n_hdlc_tty_poll - TTY callback for poll system call | |
793 | * @tty - pointer to tty instance data | |
794 | * @filp - pointer to open file object for device | |
795 | * @poll_table - wait queue for operations | |
796 | * | |
797 | * Determine which operations (read/write) will not block and return info | |
798 | * to caller. | |
799 | * Returns a bit mask containing info on which ops will not block. | |
800 | */ | |
801 | static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, | |
802 | poll_table *wait) | |
803 | { | |
804 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
805 | unsigned int mask = 0; | |
806 | ||
807 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
808 | printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__); | |
809 | ||
810 | if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) { | |
811 | /* queue current process into any wait queue that */ | |
812 | /* may awaken in the future (read and write) */ | |
813 | ||
814 | poll_wait(filp, &tty->read_wait, wait); | |
815 | poll_wait(filp, &tty->write_wait, wait); | |
816 | ||
817 | /* set bits for operations that won't block */ | |
82f2341c | 818 | if (!list_empty(&n_hdlc->rx_buf_list.list)) |
1da177e4 | 819 | mask |= POLLIN | POLLRDNORM; /* readable */ |
0f40fbbc | 820 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) |
1da177e4 | 821 | mask |= POLLHUP; |
9c1729db | 822 | if (tty_hung_up_p(filp)) |
1da177e4 | 823 | mask |= POLLHUP; |
9c1729db | 824 | if (!tty_is_writelocked(tty) && |
82f2341c | 825 | !list_empty(&n_hdlc->tx_free_buf_list.list)) |
1da177e4 LT |
826 | mask |= POLLOUT | POLLWRNORM; /* writable */ |
827 | } | |
828 | return mask; | |
829 | } /* end of n_hdlc_tty_poll() */ | |
830 | ||
831 | /** | |
832 | * n_hdlc_alloc - allocate an n_hdlc instance data structure | |
833 | * | |
834 | * Returns a pointer to newly created structure if success, otherwise %NULL | |
835 | */ | |
836 | static struct n_hdlc *n_hdlc_alloc(void) | |
837 | { | |
838 | struct n_hdlc_buf *buf; | |
839 | int i; | |
8e25f8ce | 840 | struct n_hdlc *n_hdlc = kzalloc(sizeof(*n_hdlc), GFP_KERNEL); |
1da177e4 LT |
841 | |
842 | if (!n_hdlc) | |
843 | return NULL; | |
844 | ||
e9b736d8 JS |
845 | spin_lock_init(&n_hdlc->rx_free_buf_list.spinlock); |
846 | spin_lock_init(&n_hdlc->tx_free_buf_list.spinlock); | |
847 | spin_lock_init(&n_hdlc->rx_buf_list.spinlock); | |
848 | spin_lock_init(&n_hdlc->tx_buf_list.spinlock); | |
82f2341c AP |
849 | |
850 | INIT_LIST_HEAD(&n_hdlc->rx_free_buf_list.list); | |
851 | INIT_LIST_HEAD(&n_hdlc->tx_free_buf_list.list); | |
852 | INIT_LIST_HEAD(&n_hdlc->rx_buf_list.list); | |
853 | INIT_LIST_HEAD(&n_hdlc->tx_buf_list.list); | |
854 | ||
1da177e4 LT |
855 | /* allocate free rx buffer list */ |
856 | for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) { | |
857 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); | |
858 | if (buf) | |
859 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf); | |
860 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
861 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i); | |
862 | } | |
863 | ||
864 | /* allocate free tx buffer list */ | |
865 | for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) { | |
866 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); | |
867 | if (buf) | |
868 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf); | |
869 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
870 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i); | |
871 | } | |
872 | ||
873 | /* Initialize the control block */ | |
874 | n_hdlc->magic = HDLC_MAGIC; | |
875 | n_hdlc->flags = 0; | |
876 | ||
877 | return n_hdlc; | |
878 | ||
879 | } /* end of n_hdlc_alloc() */ | |
880 | ||
82f2341c AP |
881 | /** |
882 | * n_hdlc_buf_return - put the HDLC buffer after the head of the specified list | |
883 | * @buf_list - pointer to the buffer list | |
884 | * @buf - pointer to the buffer | |
885 | */ | |
886 | static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, | |
887 | struct n_hdlc_buf *buf) | |
888 | { | |
889 | unsigned long flags; | |
890 | ||
891 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
892 | ||
893 | list_add(&buf->list_item, &buf_list->list); | |
894 | buf_list->count++; | |
895 | ||
896 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
897 | } | |
898 | ||
1da177e4 LT |
899 | /** |
900 | * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list | |
82f2341c | 901 | * @buf_list - pointer to buffer list |
1da177e4 LT |
902 | * @buf - pointer to buffer |
903 | */ | |
82f2341c | 904 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list, |
1da177e4 LT |
905 | struct n_hdlc_buf *buf) |
906 | { | |
907 | unsigned long flags; | |
82f2341c AP |
908 | |
909 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
910 | ||
911 | list_add_tail(&buf->list_item, &buf_list->list); | |
912 | buf_list->count++; | |
913 | ||
914 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
1da177e4 LT |
915 | } /* end of n_hdlc_buf_put() */ |
916 | ||
917 | /** | |
918 | * n_hdlc_buf_get - remove and return an HDLC buffer from list | |
82f2341c | 919 | * @buf_list - pointer to HDLC buffer list |
1da177e4 LT |
920 | * |
921 | * Remove and return an HDLC buffer from the head of the specified HDLC buffer | |
922 | * list. | |
923 | * Returns a pointer to HDLC buffer if available, otherwise %NULL. | |
924 | */ | |
82f2341c | 925 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list) |
1da177e4 LT |
926 | { |
927 | unsigned long flags; | |
928 | struct n_hdlc_buf *buf; | |
82f2341c AP |
929 | |
930 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
931 | ||
932 | buf = list_first_entry_or_null(&buf_list->list, | |
933 | struct n_hdlc_buf, list_item); | |
1da177e4 | 934 | if (buf) { |
82f2341c AP |
935 | list_del(&buf->list_item); |
936 | buf_list->count--; | |
1da177e4 | 937 | } |
82f2341c AP |
938 | |
939 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
1da177e4 | 940 | return buf; |
1da177e4 LT |
941 | } /* end of n_hdlc_buf_get() */ |
942 | ||
06324664 | 943 | static const char hdlc_banner[] __initconst = |
be10eb75 | 944 | KERN_INFO "HDLC line discipline maxframe=%u\n"; |
06324664 | 945 | static const char hdlc_register_ok[] __initconst = |
1da177e4 | 946 | KERN_INFO "N_HDLC line discipline registered.\n"; |
06324664 | 947 | static const char hdlc_register_fail[] __initconst = |
1da177e4 | 948 | KERN_ERR "error registering line discipline: %d\n"; |
1da177e4 LT |
949 | |
950 | static int __init n_hdlc_init(void) | |
951 | { | |
952 | int status; | |
953 | ||
954 | /* range check maxframe arg */ | |
955 | if (maxframe < 4096) | |
956 | maxframe = 4096; | |
957 | else if (maxframe > 65535) | |
958 | maxframe = 65535; | |
959 | ||
960 | printk(hdlc_banner, maxframe); | |
961 | ||
962 | status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc); | |
963 | if (!status) | |
964 | printk(hdlc_register_ok); | |
965 | else | |
966 | printk(hdlc_register_fail, status); | |
967 | ||
1da177e4 LT |
968 | return status; |
969 | ||
970 | } /* end of init_module() */ | |
971 | ||
06324664 | 972 | static const char hdlc_unregister_ok[] __exitdata = |
1da177e4 | 973 | KERN_INFO "N_HDLC: line discipline unregistered\n"; |
06324664 | 974 | static const char hdlc_unregister_fail[] __exitdata = |
1da177e4 LT |
975 | KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n"; |
976 | ||
977 | static void __exit n_hdlc_exit(void) | |
978 | { | |
979 | /* Release tty registration of line discipline */ | |
64ccd715 | 980 | int status = tty_unregister_ldisc(N_HDLC); |
1da177e4 LT |
981 | |
982 | if (status) | |
983 | printk(hdlc_unregister_fail, status); | |
984 | else | |
985 | printk(hdlc_unregister_ok); | |
986 | } | |
987 | ||
988 | module_init(n_hdlc_init); | |
989 | module_exit(n_hdlc_exit); | |
990 | ||
991 | MODULE_LICENSE("GPL"); | |
992 | MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com"); | |
993 | module_param(debuglevel, int, 0); | |
994 | module_param(maxframe, int, 0); | |
995 | MODULE_ALIAS_LDISC(N_HDLC); |