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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 | 14 | * |
1da177e4 LT |
15 | * This module implements the tty line discipline N_HDLC for use with |
16 | * tty device drivers that support bit-synchronous HDLC communications. | |
17 | * | |
18 | * All HDLC data is frame oriented which means: | |
19 | * | |
20 | * 1. tty write calls represent one complete transmit frame of data | |
21 | * The device driver should accept the complete frame or none of | |
22 | * the frame (busy) in the write method. Each write call should have | |
23 | * a byte count in the range of 2-65535 bytes (2 is min HDLC frame | |
24 | * with 1 addr byte and 1 ctrl byte). The max byte count of 65535 | |
25 | * should include any crc bytes required. For example, when using | |
26 | * CCITT CRC32, 4 crc bytes are required, so the maximum size frame | |
27 | * the application may transmit is limited to 65531 bytes. For CCITT | |
28 | * CRC16, the maximum application frame size would be 65533. | |
29 | * | |
30 | * | |
31 | * 2. receive callbacks from the device driver represents | |
32 | * one received frame. The device driver should bypass | |
33 | * the tty flip buffer and call the line discipline receive | |
34 | * callback directly to avoid fragmenting or concatenating | |
35 | * multiple frames into a single receive callback. | |
36 | * | |
37 | * The HDLC line discipline queues the receive frames in separate | |
38 | * buffers so complete receive frames can be returned by the | |
39 | * tty read calls. | |
40 | * | |
41 | * 3. tty read calls returns an entire frame of data or nothing. | |
42 | * | |
43 | * 4. all send and receive data is considered raw. No processing | |
44 | * or translation is performed by the line discipline, regardless | |
45 | * of the tty flags | |
46 | * | |
47 | * 5. When line discipline is queried for the amount of receive | |
48 | * data available (FIOC), 0 is returned if no data available, | |
49 | * otherwise the count of the next available frame is returned. | |
50 | * (instead of the sum of all received frame counts). | |
51 | * | |
52 | * These conventions allow the standard tty programming interface | |
53 | * to be used for synchronous HDLC applications when used with | |
54 | * this line discipline (or another line discipline that is frame | |
55 | * oriented such as N_PPP). | |
56 | * | |
57 | * The SyncLink driver (synclink.c) implements both asynchronous | |
58 | * (using standard line discipline N_TTY) and synchronous HDLC | |
59 | * (using N_HDLC) communications, with the latter using the above | |
60 | * conventions. | |
61 | * | |
62 | * This implementation is very basic and does not maintain | |
63 | * any statistics. The main point is to enforce the raw data | |
64 | * and frame orientation of HDLC communications. | |
65 | * | |
66 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED | |
67 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
68 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | |
69 | * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, | |
70 | * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
71 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | |
72 | * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
73 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
74 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
75 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
76 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
77 | */ | |
78 | ||
79 | #define HDLC_MAGIC 0x239e | |
1da177e4 | 80 | |
1da177e4 LT |
81 | #include <linux/module.h> |
82 | #include <linux/init.h> | |
83 | #include <linux/kernel.h> | |
84 | #include <linux/sched.h> | |
85 | #include <linux/types.h> | |
86 | #include <linux/fcntl.h> | |
87 | #include <linux/interrupt.h> | |
88 | #include <linux/ptrace.h> | |
89 | ||
90 | #undef VERSION | |
91 | #define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch)) | |
92 | ||
93 | #include <linux/poll.h> | |
94 | #include <linux/in.h> | |
95 | #include <linux/ioctl.h> | |
96 | #include <linux/slab.h> | |
97 | #include <linux/tty.h> | |
98 | #include <linux/errno.h> | |
99 | #include <linux/string.h> /* used in new tty drivers */ | |
100 | #include <linux/signal.h> /* used in new tty drivers */ | |
101 | #include <linux/if.h> | |
102 | #include <linux/bitops.h> | |
103 | ||
1da177e4 | 104 | #include <asm/termios.h> |
7c0f6ba6 | 105 | #include <linux/uaccess.h> |
1da177e4 LT |
106 | |
107 | /* | |
108 | * Buffers for individual HDLC frames | |
109 | */ | |
110 | #define MAX_HDLC_FRAME_SIZE 65535 | |
111 | #define DEFAULT_RX_BUF_COUNT 10 | |
112 | #define MAX_RX_BUF_COUNT 60 | |
be10eb75 | 113 | #define DEFAULT_TX_BUF_COUNT 3 |
1da177e4 LT |
114 | |
115 | struct n_hdlc_buf { | |
82f2341c | 116 | struct list_head list_item; |
1da177e4 LT |
117 | int count; |
118 | char buf[1]; | |
119 | }; | |
120 | ||
121 | #define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe) | |
122 | ||
123 | struct n_hdlc_buf_list { | |
82f2341c | 124 | struct list_head list; |
1da177e4 LT |
125 | int count; |
126 | spinlock_t spinlock; | |
127 | }; | |
128 | ||
129 | /** | |
130 | * struct n_hdlc - per device instance data structure | |
131 | * @magic - magic value for structure | |
132 | * @flags - miscellaneous control flags | |
133 | * @tty - ptr to TTY structure | |
134 | * @backup_tty - TTY to use if tty gets closed | |
135 | * @tbusy - reentrancy flag for tx wakeup code | |
136 | * @woke_up - FIXME: describe this field | |
1da177e4 LT |
137 | * @tx_buf_list - list of pending transmit frame buffers |
138 | * @rx_buf_list - list of received frame buffers | |
139 | * @tx_free_buf_list - list unused transmit frame buffers | |
140 | * @rx_free_buf_list - list unused received frame buffers | |
141 | */ | |
142 | struct n_hdlc { | |
143 | int magic; | |
144 | __u32 flags; | |
145 | struct tty_struct *tty; | |
146 | struct tty_struct *backup_tty; | |
147 | int tbusy; | |
148 | int woke_up; | |
1da177e4 LT |
149 | struct n_hdlc_buf_list tx_buf_list; |
150 | struct n_hdlc_buf_list rx_buf_list; | |
151 | struct n_hdlc_buf_list tx_free_buf_list; | |
152 | struct n_hdlc_buf_list rx_free_buf_list; | |
153 | }; | |
154 | ||
155 | /* | |
156 | * HDLC buffer list manipulation functions | |
157 | */ | |
82f2341c AP |
158 | static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, |
159 | struct n_hdlc_buf *buf); | |
1da177e4 LT |
160 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, |
161 | struct n_hdlc_buf *buf); | |
162 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list); | |
163 | ||
164 | /* Local functions */ | |
165 | ||
166 | static struct n_hdlc *n_hdlc_alloc (void); | |
167 | ||
168 | /* debug level can be set by insmod for debugging purposes */ | |
169 | #define DEBUG_LEVEL_INFO 1 | |
170 | static int debuglevel; | |
171 | ||
172 | /* max frame size for memory allocations */ | |
173 | static int maxframe = 4096; | |
174 | ||
175 | /* TTY callbacks */ | |
176 | ||
177 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
178 | __u8 __user *buf, size_t nr); | |
179 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
180 | const unsigned char *buf, size_t nr); | |
181 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
182 | unsigned int cmd, unsigned long arg); | |
afc9a42b | 183 | static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, |
1da177e4 LT |
184 | poll_table *wait); |
185 | static int n_hdlc_tty_open(struct tty_struct *tty); | |
186 | static void n_hdlc_tty_close(struct tty_struct *tty); | |
55db4c64 LT |
187 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp, |
188 | char *fp, int count); | |
1da177e4 LT |
189 | static void n_hdlc_tty_wakeup(struct tty_struct *tty); |
190 | ||
191 | #define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f))) | |
192 | ||
193 | #define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data)) | |
194 | #define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty) | |
195 | ||
be10eb75 PF |
196 | static void flush_rx_queue(struct tty_struct *tty) |
197 | { | |
198 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
199 | struct n_hdlc_buf *buf; | |
200 | ||
201 | while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list))) | |
202 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf); | |
203 | } | |
204 | ||
205 | static void flush_tx_queue(struct tty_struct *tty) | |
206 | { | |
207 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
208 | struct n_hdlc_buf *buf; | |
be10eb75 PF |
209 | |
210 | while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list))) | |
211 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf); | |
be10eb75 PF |
212 | } |
213 | ||
a352def2 | 214 | static struct tty_ldisc_ops n_hdlc_ldisc = { |
1da177e4 LT |
215 | .owner = THIS_MODULE, |
216 | .magic = TTY_LDISC_MAGIC, | |
217 | .name = "hdlc", | |
218 | .open = n_hdlc_tty_open, | |
219 | .close = n_hdlc_tty_close, | |
220 | .read = n_hdlc_tty_read, | |
221 | .write = n_hdlc_tty_write, | |
222 | .ioctl = n_hdlc_tty_ioctl, | |
223 | .poll = n_hdlc_tty_poll, | |
224 | .receive_buf = n_hdlc_tty_receive, | |
1da177e4 | 225 | .write_wakeup = n_hdlc_tty_wakeup, |
be10eb75 | 226 | .flush_buffer = flush_rx_queue, |
1da177e4 LT |
227 | }; |
228 | ||
229 | /** | |
230 | * n_hdlc_release - release an n_hdlc per device line discipline info structure | |
231 | * @n_hdlc - per device line discipline info structure | |
232 | */ | |
233 | static void n_hdlc_release(struct n_hdlc *n_hdlc) | |
234 | { | |
235 | struct tty_struct *tty = n_hdlc2tty (n_hdlc); | |
236 | struct n_hdlc_buf *buf; | |
237 | ||
238 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
239 | printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__); | |
240 | ||
241 | /* Ensure that the n_hdlcd process is not hanging on select()/poll() */ | |
242 | wake_up_interruptible (&tty->read_wait); | |
243 | wake_up_interruptible (&tty->write_wait); | |
244 | ||
827afdf0 | 245 | if (tty->disc_data == n_hdlc) |
1da177e4 LT |
246 | tty->disc_data = NULL; /* Break the tty->n_hdlc link */ |
247 | ||
248 | /* Release transmit and receive buffers */ | |
249 | for(;;) { | |
250 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
251 | if (buf) { | |
252 | kfree(buf); | |
253 | } else | |
254 | break; | |
255 | } | |
256 | for(;;) { | |
257 | buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); | |
258 | if (buf) { | |
259 | kfree(buf); | |
260 | } else | |
261 | break; | |
262 | } | |
263 | for(;;) { | |
264 | buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
265 | if (buf) { | |
266 | kfree(buf); | |
267 | } else | |
268 | break; | |
269 | } | |
270 | for(;;) { | |
271 | buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
272 | if (buf) { | |
273 | kfree(buf); | |
274 | } else | |
275 | break; | |
276 | } | |
1da177e4 LT |
277 | kfree(n_hdlc); |
278 | ||
279 | } /* end of n_hdlc_release() */ | |
280 | ||
281 | /** | |
282 | * n_hdlc_tty_close - line discipline close | |
283 | * @tty - pointer to tty info structure | |
284 | * | |
285 | * Called when the line discipline is changed to something | |
286 | * else, the tty is closed, or the tty detects a hangup. | |
287 | */ | |
288 | static void n_hdlc_tty_close(struct tty_struct *tty) | |
289 | { | |
290 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
291 | ||
292 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
293 | printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__); | |
294 | ||
295 | if (n_hdlc != NULL) { | |
296 | if (n_hdlc->magic != HDLC_MAGIC) { | |
297 | printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n"); | |
298 | return; | |
299 | } | |
300 | #if defined(TTY_NO_WRITE_SPLIT) | |
301 | clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
302 | #endif | |
303 | tty->disc_data = NULL; | |
304 | if (tty == n_hdlc->backup_tty) | |
305 | n_hdlc->backup_tty = NULL; | |
306 | if (tty != n_hdlc->tty) | |
307 | return; | |
308 | if (n_hdlc->backup_tty) { | |
309 | n_hdlc->tty = n_hdlc->backup_tty; | |
310 | } else { | |
311 | n_hdlc_release (n_hdlc); | |
312 | } | |
313 | } | |
314 | ||
315 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
316 | printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__); | |
317 | ||
318 | } /* end of n_hdlc_tty_close() */ | |
319 | ||
320 | /** | |
321 | * n_hdlc_tty_open - called when line discipline changed to n_hdlc | |
322 | * @tty - pointer to tty info structure | |
323 | * | |
324 | * Returns 0 if success, otherwise error code | |
325 | */ | |
326 | static int n_hdlc_tty_open (struct tty_struct *tty) | |
327 | { | |
328 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
329 | ||
330 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
331 | printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n", | |
332 | __FILE__,__LINE__, | |
333 | tty->name); | |
334 | ||
335 | /* There should not be an existing table for this slot. */ | |
336 | if (n_hdlc) { | |
337 | printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" ); | |
338 | return -EEXIST; | |
339 | } | |
340 | ||
341 | n_hdlc = n_hdlc_alloc(); | |
342 | if (!n_hdlc) { | |
343 | printk (KERN_ERR "n_hdlc_alloc failed\n"); | |
344 | return -ENFILE; | |
345 | } | |
346 | ||
347 | tty->disc_data = n_hdlc; | |
348 | n_hdlc->tty = tty; | |
33f0f88f | 349 | tty->receive_room = 65536; |
1da177e4 LT |
350 | |
351 | #if defined(TTY_NO_WRITE_SPLIT) | |
352 | /* change tty_io write() to not split large writes into 8K chunks */ | |
353 | set_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
354 | #endif | |
355 | ||
be10eb75 | 356 | /* flush receive data from driver */ |
f34d7a5b | 357 | tty_driver_flush_buffer(tty); |
1da177e4 LT |
358 | |
359 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
360 | printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__); | |
361 | ||
362 | return 0; | |
363 | ||
364 | } /* end of n_tty_hdlc_open() */ | |
365 | ||
366 | /** | |
367 | * n_hdlc_send_frames - send frames on pending send buffer list | |
368 | * @n_hdlc - pointer to ldisc instance data | |
369 | * @tty - pointer to tty instance data | |
370 | * | |
371 | * Send frames on pending send buffer list until the driver does not accept a | |
372 | * frame (busy) this function is called after adding a frame to the send buffer | |
373 | * list and by the tty wakeup callback. | |
374 | */ | |
375 | static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) | |
376 | { | |
377 | register int actual; | |
378 | unsigned long flags; | |
379 | struct n_hdlc_buf *tbuf; | |
380 | ||
381 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
382 | printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__); | |
383 | check_again: | |
384 | ||
385 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
386 | if (n_hdlc->tbusy) { | |
387 | n_hdlc->woke_up = 1; | |
388 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
389 | return; | |
390 | } | |
391 | n_hdlc->tbusy = 1; | |
392 | n_hdlc->woke_up = 0; | |
393 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
394 | ||
82f2341c | 395 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); |
1da177e4 LT |
396 | while (tbuf) { |
397 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
398 | printk("%s(%d)sending frame %p, count=%d\n", | |
399 | __FILE__,__LINE__,tbuf,tbuf->count); | |
400 | ||
401 | /* Send the next block of data to device */ | |
7962fce9 | 402 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
f34d7a5b | 403 | actual = tty->ops->write(tty, tbuf->buf, tbuf->count); |
b0fed314 JS |
404 | |
405 | /* rollback was possible and has been done */ | |
406 | if (actual == -ERESTARTSYS) { | |
82f2341c | 407 | n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); |
b0fed314 JS |
408 | break; |
409 | } | |
1da177e4 LT |
410 | /* if transmit error, throw frame away by */ |
411 | /* pretending it was accepted by driver */ | |
412 | if (actual < 0) | |
413 | actual = tbuf->count; | |
414 | ||
415 | if (actual == tbuf->count) { | |
416 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
417 | printk("%s(%d)frame %p completed\n", | |
418 | __FILE__,__LINE__,tbuf); | |
419 | ||
420 | /* free current transmit buffer */ | |
421 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf); | |
82f2341c | 422 | |
1da177e4 LT |
423 | /* wait up sleeping writers */ |
424 | wake_up_interruptible(&tty->write_wait); | |
425 | ||
426 | /* get next pending transmit buffer */ | |
427 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
428 | } else { | |
429 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
430 | printk("%s(%d)frame %p pending\n", | |
431 | __FILE__,__LINE__,tbuf); | |
82f2341c AP |
432 | |
433 | /* | |
434 | * the buffer was not accepted by driver, | |
435 | * return it back into tx queue | |
436 | */ | |
437 | n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); | |
1da177e4 LT |
438 | break; |
439 | } | |
440 | } | |
441 | ||
442 | if (!tbuf) | |
7962fce9 | 443 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
1da177e4 LT |
444 | |
445 | /* Clear the re-entry flag */ | |
446 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
447 | n_hdlc->tbusy = 0; | |
448 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
449 | ||
450 | if (n_hdlc->woke_up) | |
451 | goto check_again; | |
452 | ||
453 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
454 | printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__); | |
455 | ||
456 | } /* end of n_hdlc_send_frames() */ | |
457 | ||
458 | /** | |
459 | * n_hdlc_tty_wakeup - Callback for transmit wakeup | |
460 | * @tty - pointer to associated tty instance data | |
461 | * | |
462 | * Called when low level device driver can accept more send data. | |
463 | */ | |
464 | static void n_hdlc_tty_wakeup(struct tty_struct *tty) | |
465 | { | |
466 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
467 | ||
468 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
469 | printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__); | |
470 | ||
471 | if (!n_hdlc) | |
472 | return; | |
473 | ||
474 | if (tty != n_hdlc->tty) { | |
7962fce9 | 475 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
1da177e4 LT |
476 | return; |
477 | } | |
478 | ||
479 | n_hdlc_send_frames (n_hdlc, tty); | |
480 | ||
481 | } /* end of n_hdlc_tty_wakeup() */ | |
482 | ||
1da177e4 LT |
483 | /** |
484 | * n_hdlc_tty_receive - Called by tty driver when receive data is available | |
485 | * @tty - pointer to tty instance data | |
486 | * @data - pointer to received data | |
487 | * @flags - pointer to flags for data | |
488 | * @count - count of received data in bytes | |
489 | * | |
490 | * Called by tty low level driver when receive data is available. Data is | |
491 | * interpreted as one HDLC frame. | |
492 | */ | |
55db4c64 LT |
493 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data, |
494 | char *flags, int count) | |
1da177e4 LT |
495 | { |
496 | register struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
497 | register struct n_hdlc_buf *buf; | |
498 | ||
499 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
500 | printk("%s(%d)n_hdlc_tty_receive() called count=%d\n", | |
501 | __FILE__,__LINE__, count); | |
502 | ||
503 | /* This can happen if stuff comes in on the backup tty */ | |
a01e035e | 504 | if (!n_hdlc || tty != n_hdlc->tty) |
55db4c64 | 505 | return; |
1da177e4 LT |
506 | |
507 | /* verify line is using HDLC discipline */ | |
508 | if (n_hdlc->magic != HDLC_MAGIC) { | |
509 | printk("%s(%d) line not using HDLC discipline\n", | |
510 | __FILE__,__LINE__); | |
55db4c64 | 511 | return; |
1da177e4 LT |
512 | } |
513 | ||
514 | if ( count>maxframe ) { | |
515 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
516 | printk("%s(%d) rx count>maxframesize, data discarded\n", | |
517 | __FILE__,__LINE__); | |
55db4c64 | 518 | return; |
1da177e4 LT |
519 | } |
520 | ||
521 | /* get a free HDLC buffer */ | |
522 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
523 | if (!buf) { | |
524 | /* no buffers in free list, attempt to allocate another rx buffer */ | |
525 | /* unless the maximum count has been reached */ | |
526 | if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT) | |
527 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC); | |
528 | } | |
529 | ||
530 | if (!buf) { | |
531 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
532 | printk("%s(%d) no more rx buffers, data discarded\n", | |
533 | __FILE__,__LINE__); | |
55db4c64 | 534 | return; |
1da177e4 LT |
535 | } |
536 | ||
537 | /* copy received data to HDLC buffer */ | |
538 | memcpy(buf->buf,data,count); | |
539 | buf->count=count; | |
540 | ||
541 | /* add HDLC buffer to list of received frames */ | |
542 | n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf); | |
543 | ||
544 | /* wake up any blocked reads and perform async signalling */ | |
545 | wake_up_interruptible (&tty->read_wait); | |
546 | if (n_hdlc->tty->fasync != NULL) | |
547 | kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN); | |
548 | ||
549 | } /* end of n_hdlc_tty_receive() */ | |
550 | ||
551 | /** | |
4a4efbde | 552 | * n_hdlc_tty_read - Called to retrieve one frame of data (if available) |
1da177e4 LT |
553 | * @tty - pointer to tty instance data |
554 | * @file - pointer to open file object | |
555 | * @buf - pointer to returned data buffer | |
556 | * @nr - size of returned data buffer | |
557 | * | |
558 | * Returns the number of bytes returned or error code. | |
559 | */ | |
560 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
561 | __u8 __user *buf, size_t nr) | |
562 | { | |
563 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
1035b63d | 564 | int ret = 0; |
1da177e4 | 565 | struct n_hdlc_buf *rbuf; |
1035b63d | 566 | DECLARE_WAITQUEUE(wait, current); |
1da177e4 LT |
567 | |
568 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
569 | printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__); | |
570 | ||
571 | /* Validate the pointers */ | |
572 | if (!n_hdlc) | |
573 | return -EIO; | |
574 | ||
575 | /* verify user access to buffer */ | |
576 | if (!access_ok(VERIFY_WRITE, buf, nr)) { | |
577 | printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user " | |
578 | "buffer\n", __FILE__, __LINE__); | |
579 | return -EFAULT; | |
580 | } | |
581 | ||
1035b63d | 582 | add_wait_queue(&tty->read_wait, &wait); |
04f378b1 | 583 | |
1da177e4 | 584 | for (;;) { |
0f40fbbc | 585 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { |
1035b63d PF |
586 | ret = -EIO; |
587 | break; | |
04f378b1 | 588 | } |
1035b63d PF |
589 | if (tty_hung_up_p(file)) |
590 | break; | |
1da177e4 | 591 | |
1035b63d | 592 | set_current_state(TASK_INTERRUPTIBLE); |
1da177e4 LT |
593 | |
594 | rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
1035b63d PF |
595 | if (rbuf) { |
596 | if (rbuf->count > nr) { | |
597 | /* too large for caller's buffer */ | |
598 | ret = -EOVERFLOW; | |
599 | } else { | |
600 | if (copy_to_user(buf, rbuf->buf, rbuf->count)) | |
601 | ret = -EFAULT; | |
602 | else | |
603 | ret = rbuf->count; | |
604 | } | |
605 | ||
606 | if (n_hdlc->rx_free_buf_list.count > | |
607 | DEFAULT_RX_BUF_COUNT) | |
608 | kfree(rbuf); | |
609 | else | |
610 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf); | |
1da177e4 | 611 | break; |
1035b63d | 612 | } |
1da177e4 LT |
613 | |
614 | /* no data */ | |
04f378b1 | 615 | if (file->f_flags & O_NONBLOCK) { |
1035b63d PF |
616 | ret = -EAGAIN; |
617 | break; | |
04f378b1 | 618 | } |
1035b63d PF |
619 | |
620 | schedule(); | |
621 | ||
04f378b1 | 622 | if (signal_pending(current)) { |
1035b63d PF |
623 | ret = -EINTR; |
624 | break; | |
04f378b1 | 625 | } |
1da177e4 | 626 | } |
1035b63d PF |
627 | |
628 | remove_wait_queue(&tty->read_wait, &wait); | |
629 | __set_current_state(TASK_RUNNING); | |
630 | ||
1da177e4 LT |
631 | return ret; |
632 | ||
633 | } /* end of n_hdlc_tty_read() */ | |
634 | ||
635 | /** | |
636 | * n_hdlc_tty_write - write a single frame of data to device | |
637 | * @tty - pointer to associated tty device instance data | |
638 | * @file - pointer to file object data | |
639 | * @data - pointer to transmit data (one frame) | |
640 | * @count - size of transmit frame in bytes | |
641 | * | |
642 | * Returns the number of bytes written (or error code). | |
643 | */ | |
644 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
645 | const unsigned char *data, size_t count) | |
646 | { | |
647 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
648 | int error = 0; | |
649 | DECLARE_WAITQUEUE(wait, current); | |
650 | struct n_hdlc_buf *tbuf; | |
651 | ||
652 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
5b5e0928 | 653 | printk("%s(%d)n_hdlc_tty_write() called count=%zd\n", |
1da177e4 LT |
654 | __FILE__,__LINE__,count); |
655 | ||
656 | /* Verify pointers */ | |
657 | if (!n_hdlc) | |
658 | return -EIO; | |
659 | ||
660 | if (n_hdlc->magic != HDLC_MAGIC) | |
661 | return -EIO; | |
662 | ||
663 | /* verify frame size */ | |
664 | if (count > maxframe ) { | |
665 | if (debuglevel & DEBUG_LEVEL_INFO) | |
666 | printk (KERN_WARNING | |
667 | "n_hdlc_tty_write: truncating user packet " | |
668 | "from %lu to %d\n", (unsigned long) count, | |
669 | maxframe ); | |
670 | count = maxframe; | |
671 | } | |
672 | ||
673 | add_wait_queue(&tty->write_wait, &wait); | |
1035b63d PF |
674 | |
675 | for (;;) { | |
676 | set_current_state(TASK_INTERRUPTIBLE); | |
1da177e4 | 677 | |
1035b63d PF |
678 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); |
679 | if (tbuf) | |
680 | break; | |
681 | ||
c72f527c PF |
682 | if (file->f_flags & O_NONBLOCK) { |
683 | error = -EAGAIN; | |
684 | break; | |
685 | } | |
1da177e4 LT |
686 | schedule(); |
687 | ||
688 | n_hdlc = tty2n_hdlc (tty); | |
689 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || | |
690 | tty != n_hdlc->tty) { | |
691 | printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc); | |
692 | error = -EIO; | |
693 | break; | |
694 | } | |
695 | ||
696 | if (signal_pending(current)) { | |
697 | error = -EINTR; | |
698 | break; | |
699 | } | |
700 | } | |
701 | ||
1035b63d | 702 | __set_current_state(TASK_RUNNING); |
1da177e4 LT |
703 | remove_wait_queue(&tty->write_wait, &wait); |
704 | ||
705 | if (!error) { | |
706 | /* Retrieve the user's buffer */ | |
707 | memcpy(tbuf->buf, data, count); | |
708 | ||
709 | /* Send the data */ | |
710 | tbuf->count = error = count; | |
711 | n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf); | |
712 | n_hdlc_send_frames(n_hdlc,tty); | |
713 | } | |
1035b63d | 714 | |
1da177e4 LT |
715 | return error; |
716 | ||
717 | } /* end of n_hdlc_tty_write() */ | |
718 | ||
719 | /** | |
720 | * n_hdlc_tty_ioctl - process IOCTL system call for the tty device. | |
721 | * @tty - pointer to tty instance data | |
722 | * @file - pointer to open file object for device | |
723 | * @cmd - IOCTL command code | |
724 | * @arg - argument for IOCTL call (cmd dependent) | |
725 | * | |
726 | * Returns command dependent result. | |
727 | */ | |
728 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
729 | unsigned int cmd, unsigned long arg) | |
730 | { | |
731 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
732 | int error = 0; | |
733 | int count; | |
734 | unsigned long flags; | |
82f2341c AP |
735 | struct n_hdlc_buf *buf = NULL; |
736 | ||
1da177e4 LT |
737 | if (debuglevel >= DEBUG_LEVEL_INFO) |
738 | printk("%s(%d)n_hdlc_tty_ioctl() called %d\n", | |
739 | __FILE__,__LINE__,cmd); | |
740 | ||
741 | /* Verify the status of the device */ | |
742 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC) | |
743 | return -EBADF; | |
744 | ||
745 | switch (cmd) { | |
746 | case FIONREAD: | |
747 | /* report count of read data available */ | |
748 | /* in next available frame (if any) */ | |
749 | spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags); | |
82f2341c AP |
750 | buf = list_first_entry_or_null(&n_hdlc->rx_buf_list.list, |
751 | struct n_hdlc_buf, list_item); | |
752 | if (buf) | |
753 | count = buf->count; | |
1da177e4 LT |
754 | else |
755 | count = 0; | |
756 | spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags); | |
757 | error = put_user(count, (int __user *)arg); | |
758 | break; | |
759 | ||
760 | case TIOCOUTQ: | |
761 | /* get the pending tx byte count in the driver */ | |
f34d7a5b | 762 | count = tty_chars_in_buffer(tty); |
1da177e4 LT |
763 | /* add size of next output frame in queue */ |
764 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags); | |
82f2341c AP |
765 | buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list, |
766 | struct n_hdlc_buf, list_item); | |
767 | if (buf) | |
768 | count += buf->count; | |
1da177e4 LT |
769 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags); |
770 | error = put_user(count, (int __user *)arg); | |
771 | break; | |
772 | ||
be10eb75 PF |
773 | case TCFLSH: |
774 | switch (arg) { | |
775 | case TCIOFLUSH: | |
776 | case TCOFLUSH: | |
777 | flush_tx_queue(tty); | |
778 | } | |
779 | /* fall through to default */ | |
780 | ||
1da177e4 | 781 | default: |
47afa7a5 | 782 | error = n_tty_ioctl_helper(tty, file, cmd, arg); |
1da177e4 LT |
783 | break; |
784 | } | |
785 | return error; | |
786 | ||
787 | } /* end of n_hdlc_tty_ioctl() */ | |
788 | ||
789 | /** | |
790 | * n_hdlc_tty_poll - TTY callback for poll system call | |
791 | * @tty - pointer to tty instance data | |
792 | * @filp - pointer to open file object for device | |
793 | * @poll_table - wait queue for operations | |
794 | * | |
795 | * Determine which operations (read/write) will not block and return info | |
796 | * to caller. | |
797 | * Returns a bit mask containing info on which ops will not block. | |
798 | */ | |
afc9a42b | 799 | static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, |
1da177e4 LT |
800 | poll_table *wait) |
801 | { | |
802 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
afc9a42b | 803 | __poll_t mask = 0; |
1da177e4 LT |
804 | |
805 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
806 | printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__); | |
807 | ||
808 | if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) { | |
809 | /* queue current process into any wait queue that */ | |
810 | /* may awaken in the future (read and write) */ | |
811 | ||
812 | poll_wait(filp, &tty->read_wait, wait); | |
813 | poll_wait(filp, &tty->write_wait, wait); | |
814 | ||
815 | /* set bits for operations that won't block */ | |
82f2341c | 816 | if (!list_empty(&n_hdlc->rx_buf_list.list)) |
1da177e4 | 817 | mask |= POLLIN | POLLRDNORM; /* readable */ |
0f40fbbc | 818 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) |
1da177e4 | 819 | mask |= POLLHUP; |
9c1729db | 820 | if (tty_hung_up_p(filp)) |
1da177e4 | 821 | mask |= POLLHUP; |
9c1729db | 822 | if (!tty_is_writelocked(tty) && |
82f2341c | 823 | !list_empty(&n_hdlc->tx_free_buf_list.list)) |
1da177e4 LT |
824 | mask |= POLLOUT | POLLWRNORM; /* writable */ |
825 | } | |
826 | return mask; | |
827 | } /* end of n_hdlc_tty_poll() */ | |
828 | ||
829 | /** | |
830 | * n_hdlc_alloc - allocate an n_hdlc instance data structure | |
831 | * | |
832 | * Returns a pointer to newly created structure if success, otherwise %NULL | |
833 | */ | |
834 | static struct n_hdlc *n_hdlc_alloc(void) | |
835 | { | |
836 | struct n_hdlc_buf *buf; | |
837 | int i; | |
8e25f8ce | 838 | struct n_hdlc *n_hdlc = kzalloc(sizeof(*n_hdlc), GFP_KERNEL); |
1da177e4 LT |
839 | |
840 | if (!n_hdlc) | |
841 | return NULL; | |
842 | ||
e9b736d8 JS |
843 | spin_lock_init(&n_hdlc->rx_free_buf_list.spinlock); |
844 | spin_lock_init(&n_hdlc->tx_free_buf_list.spinlock); | |
845 | spin_lock_init(&n_hdlc->rx_buf_list.spinlock); | |
846 | spin_lock_init(&n_hdlc->tx_buf_list.spinlock); | |
82f2341c AP |
847 | |
848 | INIT_LIST_HEAD(&n_hdlc->rx_free_buf_list.list); | |
849 | INIT_LIST_HEAD(&n_hdlc->tx_free_buf_list.list); | |
850 | INIT_LIST_HEAD(&n_hdlc->rx_buf_list.list); | |
851 | INIT_LIST_HEAD(&n_hdlc->tx_buf_list.list); | |
852 | ||
1da177e4 LT |
853 | /* allocate free rx buffer list */ |
854 | for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) { | |
855 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); | |
856 | if (buf) | |
857 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf); | |
858 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
859 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i); | |
860 | } | |
861 | ||
862 | /* allocate free tx buffer list */ | |
863 | for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) { | |
864 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); | |
865 | if (buf) | |
866 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf); | |
867 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
868 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i); | |
869 | } | |
870 | ||
871 | /* Initialize the control block */ | |
872 | n_hdlc->magic = HDLC_MAGIC; | |
873 | n_hdlc->flags = 0; | |
874 | ||
875 | return n_hdlc; | |
876 | ||
877 | } /* end of n_hdlc_alloc() */ | |
878 | ||
82f2341c AP |
879 | /** |
880 | * n_hdlc_buf_return - put the HDLC buffer after the head of the specified list | |
881 | * @buf_list - pointer to the buffer list | |
882 | * @buf - pointer to the buffer | |
883 | */ | |
884 | static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, | |
885 | struct n_hdlc_buf *buf) | |
886 | { | |
887 | unsigned long flags; | |
888 | ||
889 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
890 | ||
891 | list_add(&buf->list_item, &buf_list->list); | |
892 | buf_list->count++; | |
893 | ||
894 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
895 | } | |
896 | ||
1da177e4 LT |
897 | /** |
898 | * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list | |
82f2341c | 899 | * @buf_list - pointer to buffer list |
1da177e4 LT |
900 | * @buf - pointer to buffer |
901 | */ | |
82f2341c | 902 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list, |
1da177e4 LT |
903 | struct n_hdlc_buf *buf) |
904 | { | |
905 | unsigned long flags; | |
82f2341c AP |
906 | |
907 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
908 | ||
909 | list_add_tail(&buf->list_item, &buf_list->list); | |
910 | buf_list->count++; | |
911 | ||
912 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
1da177e4 LT |
913 | } /* end of n_hdlc_buf_put() */ |
914 | ||
915 | /** | |
916 | * n_hdlc_buf_get - remove and return an HDLC buffer from list | |
82f2341c | 917 | * @buf_list - pointer to HDLC buffer list |
1da177e4 LT |
918 | * |
919 | * Remove and return an HDLC buffer from the head of the specified HDLC buffer | |
920 | * list. | |
921 | * Returns a pointer to HDLC buffer if available, otherwise %NULL. | |
922 | */ | |
82f2341c | 923 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list) |
1da177e4 LT |
924 | { |
925 | unsigned long flags; | |
926 | struct n_hdlc_buf *buf; | |
82f2341c AP |
927 | |
928 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
929 | ||
930 | buf = list_first_entry_or_null(&buf_list->list, | |
931 | struct n_hdlc_buf, list_item); | |
1da177e4 | 932 | if (buf) { |
82f2341c AP |
933 | list_del(&buf->list_item); |
934 | buf_list->count--; | |
1da177e4 | 935 | } |
82f2341c AP |
936 | |
937 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
1da177e4 | 938 | return buf; |
1da177e4 LT |
939 | } /* end of n_hdlc_buf_get() */ |
940 | ||
06324664 | 941 | static const char hdlc_banner[] __initconst = |
be10eb75 | 942 | KERN_INFO "HDLC line discipline maxframe=%u\n"; |
06324664 | 943 | static const char hdlc_register_ok[] __initconst = |
1da177e4 | 944 | KERN_INFO "N_HDLC line discipline registered.\n"; |
06324664 | 945 | static const char hdlc_register_fail[] __initconst = |
1da177e4 | 946 | KERN_ERR "error registering line discipline: %d\n"; |
1da177e4 LT |
947 | |
948 | static int __init n_hdlc_init(void) | |
949 | { | |
950 | int status; | |
951 | ||
952 | /* range check maxframe arg */ | |
953 | if (maxframe < 4096) | |
954 | maxframe = 4096; | |
955 | else if (maxframe > 65535) | |
956 | maxframe = 65535; | |
957 | ||
958 | printk(hdlc_banner, maxframe); | |
959 | ||
960 | status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc); | |
961 | if (!status) | |
962 | printk(hdlc_register_ok); | |
963 | else | |
964 | printk(hdlc_register_fail, status); | |
965 | ||
1da177e4 LT |
966 | return status; |
967 | ||
968 | } /* end of init_module() */ | |
969 | ||
06324664 | 970 | static const char hdlc_unregister_ok[] __exitdata = |
1da177e4 | 971 | KERN_INFO "N_HDLC: line discipline unregistered\n"; |
06324664 | 972 | static const char hdlc_unregister_fail[] __exitdata = |
1da177e4 LT |
973 | KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n"; |
974 | ||
975 | static void __exit n_hdlc_exit(void) | |
976 | { | |
977 | /* Release tty registration of line discipline */ | |
64ccd715 | 978 | int status = tty_unregister_ldisc(N_HDLC); |
1da177e4 LT |
979 | |
980 | if (status) | |
981 | printk(hdlc_unregister_fail, status); | |
982 | else | |
983 | printk(hdlc_unregister_ok); | |
984 | } | |
985 | ||
986 | module_init(n_hdlc_init); | |
987 | module_exit(n_hdlc_exit); | |
988 | ||
989 | MODULE_LICENSE("GPL"); | |
990 | MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com"); | |
991 | module_param(debuglevel, int, 0); | |
992 | module_param(maxframe, int, 0); | |
993 | MODULE_ALIAS_LDISC(N_HDLC); |