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1da177e4 LT |
1 | /* generic HDLC line discipline for Linux |
2 | * | |
3 | * Written by Paul Fulghum paulkf@microgate.com | |
4 | * for Microgate Corporation | |
5 | * | |
6 | * Microgate and SyncLink are registered trademarks of Microgate Corporation | |
7 | * | |
8 | * Adapted from ppp.c, written by Michael Callahan <callahan@maths.ox.ac.uk>, | |
9 | * Al Longyear <longyear@netcom.com>, | |
10 | * Paul Mackerras <Paul.Mackerras@cs.anu.edu.au> | |
11 | * | |
12 | * Original release 01/11/99 | |
13 | * $Id: n_hdlc.c,v 4.8 2003/05/06 21:18:51 paulkf Exp $ | |
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 | |
82 | #define HDLC_VERSION "$Revision: 4.8 $" | |
83 | ||
84 | #include <linux/config.h> | |
85 | #include <linux/module.h> | |
86 | #include <linux/init.h> | |
87 | #include <linux/kernel.h> | |
88 | #include <linux/sched.h> | |
89 | #include <linux/types.h> | |
90 | #include <linux/fcntl.h> | |
91 | #include <linux/interrupt.h> | |
92 | #include <linux/ptrace.h> | |
93 | ||
94 | #undef VERSION | |
95 | #define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch)) | |
96 | ||
97 | #include <linux/poll.h> | |
98 | #include <linux/in.h> | |
99 | #include <linux/ioctl.h> | |
100 | #include <linux/slab.h> | |
101 | #include <linux/tty.h> | |
102 | #include <linux/errno.h> | |
103 | #include <linux/string.h> /* used in new tty drivers */ | |
104 | #include <linux/signal.h> /* used in new tty drivers */ | |
105 | #include <linux/if.h> | |
106 | #include <linux/bitops.h> | |
107 | ||
108 | #include <asm/system.h> | |
109 | #include <asm/termios.h> | |
110 | #include <asm/uaccess.h> | |
111 | ||
112 | /* | |
113 | * Buffers for individual HDLC frames | |
114 | */ | |
115 | #define MAX_HDLC_FRAME_SIZE 65535 | |
116 | #define DEFAULT_RX_BUF_COUNT 10 | |
117 | #define MAX_RX_BUF_COUNT 60 | |
118 | #define DEFAULT_TX_BUF_COUNT 1 | |
119 | ||
120 | struct n_hdlc_buf { | |
121 | struct n_hdlc_buf *link; | |
122 | int count; | |
123 | char buf[1]; | |
124 | }; | |
125 | ||
126 | #define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe) | |
127 | ||
128 | struct n_hdlc_buf_list { | |
129 | struct n_hdlc_buf *head; | |
130 | struct n_hdlc_buf *tail; | |
131 | int count; | |
132 | spinlock_t spinlock; | |
133 | }; | |
134 | ||
135 | /** | |
136 | * struct n_hdlc - per device instance data structure | |
137 | * @magic - magic value for structure | |
138 | * @flags - miscellaneous control flags | |
139 | * @tty - ptr to TTY structure | |
140 | * @backup_tty - TTY to use if tty gets closed | |
141 | * @tbusy - reentrancy flag for tx wakeup code | |
142 | * @woke_up - FIXME: describe this field | |
143 | * @tbuf - currently transmitting tx buffer | |
144 | * @tx_buf_list - list of pending transmit frame buffers | |
145 | * @rx_buf_list - list of received frame buffers | |
146 | * @tx_free_buf_list - list unused transmit frame buffers | |
147 | * @rx_free_buf_list - list unused received frame buffers | |
148 | */ | |
149 | struct n_hdlc { | |
150 | int magic; | |
151 | __u32 flags; | |
152 | struct tty_struct *tty; | |
153 | struct tty_struct *backup_tty; | |
154 | int tbusy; | |
155 | int woke_up; | |
156 | struct n_hdlc_buf *tbuf; | |
157 | struct n_hdlc_buf_list tx_buf_list; | |
158 | struct n_hdlc_buf_list rx_buf_list; | |
159 | struct n_hdlc_buf_list tx_free_buf_list; | |
160 | struct n_hdlc_buf_list rx_free_buf_list; | |
161 | }; | |
162 | ||
163 | /* | |
164 | * HDLC buffer list manipulation functions | |
165 | */ | |
166 | static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list); | |
167 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, | |
168 | struct n_hdlc_buf *buf); | |
169 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list); | |
170 | ||
171 | /* Local functions */ | |
172 | ||
173 | static struct n_hdlc *n_hdlc_alloc (void); | |
174 | ||
175 | /* debug level can be set by insmod for debugging purposes */ | |
176 | #define DEBUG_LEVEL_INFO 1 | |
177 | static int debuglevel; | |
178 | ||
179 | /* max frame size for memory allocations */ | |
180 | static int maxframe = 4096; | |
181 | ||
182 | /* TTY callbacks */ | |
183 | ||
184 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
185 | __u8 __user *buf, size_t nr); | |
186 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
187 | const unsigned char *buf, size_t nr); | |
188 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
189 | unsigned int cmd, unsigned long arg); | |
190 | static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, | |
191 | poll_table *wait); | |
192 | static int n_hdlc_tty_open(struct tty_struct *tty); | |
193 | static void n_hdlc_tty_close(struct tty_struct *tty); | |
194 | static int n_hdlc_tty_room(struct tty_struct *tty); | |
195 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp, | |
196 | char *fp, int count); | |
197 | static void n_hdlc_tty_wakeup(struct tty_struct *tty); | |
198 | ||
199 | #define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f))) | |
200 | ||
201 | #define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data)) | |
202 | #define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty) | |
203 | ||
204 | static struct tty_ldisc n_hdlc_ldisc = { | |
205 | .owner = THIS_MODULE, | |
206 | .magic = TTY_LDISC_MAGIC, | |
207 | .name = "hdlc", | |
208 | .open = n_hdlc_tty_open, | |
209 | .close = n_hdlc_tty_close, | |
210 | .read = n_hdlc_tty_read, | |
211 | .write = n_hdlc_tty_write, | |
212 | .ioctl = n_hdlc_tty_ioctl, | |
213 | .poll = n_hdlc_tty_poll, | |
214 | .receive_buf = n_hdlc_tty_receive, | |
215 | .receive_room = n_hdlc_tty_room, | |
216 | .write_wakeup = n_hdlc_tty_wakeup, | |
217 | }; | |
218 | ||
219 | /** | |
220 | * n_hdlc_release - release an n_hdlc per device line discipline info structure | |
221 | * @n_hdlc - per device line discipline info structure | |
222 | */ | |
223 | static void n_hdlc_release(struct n_hdlc *n_hdlc) | |
224 | { | |
225 | struct tty_struct *tty = n_hdlc2tty (n_hdlc); | |
226 | struct n_hdlc_buf *buf; | |
227 | ||
228 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
229 | printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__); | |
230 | ||
231 | /* Ensure that the n_hdlcd process is not hanging on select()/poll() */ | |
232 | wake_up_interruptible (&tty->read_wait); | |
233 | wake_up_interruptible (&tty->write_wait); | |
234 | ||
235 | if (tty != NULL && tty->disc_data == n_hdlc) | |
236 | tty->disc_data = NULL; /* Break the tty->n_hdlc link */ | |
237 | ||
238 | /* Release transmit and receive buffers */ | |
239 | for(;;) { | |
240 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
241 | if (buf) { | |
242 | kfree(buf); | |
243 | } else | |
244 | break; | |
245 | } | |
246 | for(;;) { | |
247 | buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); | |
248 | if (buf) { | |
249 | kfree(buf); | |
250 | } else | |
251 | break; | |
252 | } | |
253 | for(;;) { | |
254 | buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
255 | if (buf) { | |
256 | kfree(buf); | |
257 | } else | |
258 | break; | |
259 | } | |
260 | for(;;) { | |
261 | buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
262 | if (buf) { | |
263 | kfree(buf); | |
264 | } else | |
265 | break; | |
266 | } | |
735d5661 | 267 | kfree(n_hdlc->tbuf); |
1da177e4 LT |
268 | kfree(n_hdlc); |
269 | ||
270 | } /* end of n_hdlc_release() */ | |
271 | ||
272 | /** | |
273 | * n_hdlc_tty_close - line discipline close | |
274 | * @tty - pointer to tty info structure | |
275 | * | |
276 | * Called when the line discipline is changed to something | |
277 | * else, the tty is closed, or the tty detects a hangup. | |
278 | */ | |
279 | static void n_hdlc_tty_close(struct tty_struct *tty) | |
280 | { | |
281 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
282 | ||
283 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
284 | printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__); | |
285 | ||
286 | if (n_hdlc != NULL) { | |
287 | if (n_hdlc->magic != HDLC_MAGIC) { | |
288 | printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n"); | |
289 | return; | |
290 | } | |
291 | #if defined(TTY_NO_WRITE_SPLIT) | |
292 | clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
293 | #endif | |
294 | tty->disc_data = NULL; | |
295 | if (tty == n_hdlc->backup_tty) | |
296 | n_hdlc->backup_tty = NULL; | |
297 | if (tty != n_hdlc->tty) | |
298 | return; | |
299 | if (n_hdlc->backup_tty) { | |
300 | n_hdlc->tty = n_hdlc->backup_tty; | |
301 | } else { | |
302 | n_hdlc_release (n_hdlc); | |
303 | } | |
304 | } | |
305 | ||
306 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
307 | printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__); | |
308 | ||
309 | } /* end of n_hdlc_tty_close() */ | |
310 | ||
311 | /** | |
312 | * n_hdlc_tty_open - called when line discipline changed to n_hdlc | |
313 | * @tty - pointer to tty info structure | |
314 | * | |
315 | * Returns 0 if success, otherwise error code | |
316 | */ | |
317 | static int n_hdlc_tty_open (struct tty_struct *tty) | |
318 | { | |
319 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
320 | ||
321 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
322 | printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n", | |
323 | __FILE__,__LINE__, | |
324 | tty->name); | |
325 | ||
326 | /* There should not be an existing table for this slot. */ | |
327 | if (n_hdlc) { | |
328 | printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" ); | |
329 | return -EEXIST; | |
330 | } | |
331 | ||
332 | n_hdlc = n_hdlc_alloc(); | |
333 | if (!n_hdlc) { | |
334 | printk (KERN_ERR "n_hdlc_alloc failed\n"); | |
335 | return -ENFILE; | |
336 | } | |
337 | ||
338 | tty->disc_data = n_hdlc; | |
339 | n_hdlc->tty = tty; | |
340 | ||
341 | #if defined(TTY_NO_WRITE_SPLIT) | |
342 | /* change tty_io write() to not split large writes into 8K chunks */ | |
343 | set_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
344 | #endif | |
345 | ||
346 | /* Flush any pending characters in the driver and discipline. */ | |
347 | ||
348 | if (tty->ldisc.flush_buffer) | |
349 | tty->ldisc.flush_buffer (tty); | |
350 | ||
351 | if (tty->driver->flush_buffer) | |
352 | tty->driver->flush_buffer (tty); | |
353 | ||
354 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
355 | printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__); | |
356 | ||
357 | return 0; | |
358 | ||
359 | } /* end of n_tty_hdlc_open() */ | |
360 | ||
361 | /** | |
362 | * n_hdlc_send_frames - send frames on pending send buffer list | |
363 | * @n_hdlc - pointer to ldisc instance data | |
364 | * @tty - pointer to tty instance data | |
365 | * | |
366 | * Send frames on pending send buffer list until the driver does not accept a | |
367 | * frame (busy) this function is called after adding a frame to the send buffer | |
368 | * list and by the tty wakeup callback. | |
369 | */ | |
370 | static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) | |
371 | { | |
372 | register int actual; | |
373 | unsigned long flags; | |
374 | struct n_hdlc_buf *tbuf; | |
375 | ||
376 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
377 | printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__); | |
378 | check_again: | |
379 | ||
380 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
381 | if (n_hdlc->tbusy) { | |
382 | n_hdlc->woke_up = 1; | |
383 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
384 | return; | |
385 | } | |
386 | n_hdlc->tbusy = 1; | |
387 | n_hdlc->woke_up = 0; | |
388 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
389 | ||
390 | /* get current transmit buffer or get new transmit */ | |
391 | /* buffer from list of pending transmit buffers */ | |
392 | ||
393 | tbuf = n_hdlc->tbuf; | |
394 | if (!tbuf) | |
395 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
396 | ||
397 | 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 */ | |
403 | tty->flags |= (1 << TTY_DO_WRITE_WAKEUP); | |
404 | actual = tty->driver->write(tty, tbuf->buf, tbuf->count); | |
405 | ||
406 | /* if transmit error, throw frame away by */ | |
407 | /* pretending it was accepted by driver */ | |
408 | if (actual < 0) | |
409 | actual = tbuf->count; | |
410 | ||
411 | if (actual == tbuf->count) { | |
412 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
413 | printk("%s(%d)frame %p completed\n", | |
414 | __FILE__,__LINE__,tbuf); | |
415 | ||
416 | /* free current transmit buffer */ | |
417 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf); | |
418 | ||
419 | /* this tx buffer is done */ | |
420 | n_hdlc->tbuf = NULL; | |
421 | ||
422 | /* wait up sleeping writers */ | |
423 | wake_up_interruptible(&tty->write_wait); | |
424 | ||
425 | /* get next pending transmit buffer */ | |
426 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
427 | } else { | |
428 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
429 | printk("%s(%d)frame %p pending\n", | |
430 | __FILE__,__LINE__,tbuf); | |
431 | ||
432 | /* buffer not accepted by driver */ | |
433 | /* set this buffer as pending buffer */ | |
434 | n_hdlc->tbuf = tbuf; | |
435 | break; | |
436 | } | |
437 | } | |
438 | ||
439 | if (!tbuf) | |
440 | tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP); | |
441 | ||
442 | /* Clear the re-entry flag */ | |
443 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
444 | n_hdlc->tbusy = 0; | |
445 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
446 | ||
447 | if (n_hdlc->woke_up) | |
448 | goto check_again; | |
449 | ||
450 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
451 | printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__); | |
452 | ||
453 | } /* end of n_hdlc_send_frames() */ | |
454 | ||
455 | /** | |
456 | * n_hdlc_tty_wakeup - Callback for transmit wakeup | |
457 | * @tty - pointer to associated tty instance data | |
458 | * | |
459 | * Called when low level device driver can accept more send data. | |
460 | */ | |
461 | static void n_hdlc_tty_wakeup(struct tty_struct *tty) | |
462 | { | |
463 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
464 | ||
465 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
466 | printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__); | |
467 | ||
468 | if (!n_hdlc) | |
469 | return; | |
470 | ||
471 | if (tty != n_hdlc->tty) { | |
472 | tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP); | |
473 | return; | |
474 | } | |
475 | ||
476 | n_hdlc_send_frames (n_hdlc, tty); | |
477 | ||
478 | } /* end of n_hdlc_tty_wakeup() */ | |
479 | ||
480 | /** | |
481 | * n_hdlc_tty_room - Return the amount of space left in the receiver's buffer | |
482 | * @tty - pointer to associated tty instance data | |
483 | * | |
484 | * Callback function from tty driver. Return the amount of space left in the | |
485 | * receiver's buffer to decide if remote transmitter is to be throttled. | |
486 | */ | |
487 | static int n_hdlc_tty_room(struct tty_struct *tty) | |
488 | { | |
489 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
490 | printk("%s(%d)n_hdlc_tty_room() called\n",__FILE__,__LINE__); | |
491 | /* always return a larger number to prevent */ | |
492 | /* throttling of remote transmitter. */ | |
493 | return 65536; | |
494 | } /* end of n_hdlc_tty_root() */ | |
495 | ||
496 | /** | |
497 | * n_hdlc_tty_receive - Called by tty driver when receive data is available | |
498 | * @tty - pointer to tty instance data | |
499 | * @data - pointer to received data | |
500 | * @flags - pointer to flags for data | |
501 | * @count - count of received data in bytes | |
502 | * | |
503 | * Called by tty low level driver when receive data is available. Data is | |
504 | * interpreted as one HDLC frame. | |
505 | */ | |
506 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data, | |
507 | char *flags, int count) | |
508 | { | |
509 | register struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
510 | register struct n_hdlc_buf *buf; | |
511 | ||
512 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
513 | printk("%s(%d)n_hdlc_tty_receive() called count=%d\n", | |
514 | __FILE__,__LINE__, count); | |
515 | ||
516 | /* This can happen if stuff comes in on the backup tty */ | |
517 | if (n_hdlc == 0 || tty != n_hdlc->tty) | |
518 | return; | |
519 | ||
520 | /* verify line is using HDLC discipline */ | |
521 | if (n_hdlc->magic != HDLC_MAGIC) { | |
522 | printk("%s(%d) line not using HDLC discipline\n", | |
523 | __FILE__,__LINE__); | |
524 | return; | |
525 | } | |
526 | ||
527 | if ( count>maxframe ) { | |
528 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
529 | printk("%s(%d) rx count>maxframesize, data discarded\n", | |
530 | __FILE__,__LINE__); | |
531 | return; | |
532 | } | |
533 | ||
534 | /* get a free HDLC buffer */ | |
535 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
536 | if (!buf) { | |
537 | /* no buffers in free list, attempt to allocate another rx buffer */ | |
538 | /* unless the maximum count has been reached */ | |
539 | if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT) | |
540 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC); | |
541 | } | |
542 | ||
543 | if (!buf) { | |
544 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
545 | printk("%s(%d) no more rx buffers, data discarded\n", | |
546 | __FILE__,__LINE__); | |
547 | return; | |
548 | } | |
549 | ||
550 | /* copy received data to HDLC buffer */ | |
551 | memcpy(buf->buf,data,count); | |
552 | buf->count=count; | |
553 | ||
554 | /* add HDLC buffer to list of received frames */ | |
555 | n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf); | |
556 | ||
557 | /* wake up any blocked reads and perform async signalling */ | |
558 | wake_up_interruptible (&tty->read_wait); | |
559 | if (n_hdlc->tty->fasync != NULL) | |
560 | kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN); | |
561 | ||
562 | } /* end of n_hdlc_tty_receive() */ | |
563 | ||
564 | /** | |
4a4efbde | 565 | * n_hdlc_tty_read - Called to retrieve one frame of data (if available) |
1da177e4 LT |
566 | * @tty - pointer to tty instance data |
567 | * @file - pointer to open file object | |
568 | * @buf - pointer to returned data buffer | |
569 | * @nr - size of returned data buffer | |
570 | * | |
571 | * Returns the number of bytes returned or error code. | |
572 | */ | |
573 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
574 | __u8 __user *buf, size_t nr) | |
575 | { | |
576 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
577 | int ret; | |
578 | struct n_hdlc_buf *rbuf; | |
579 | ||
580 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
581 | printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__); | |
582 | ||
583 | /* Validate the pointers */ | |
584 | if (!n_hdlc) | |
585 | return -EIO; | |
586 | ||
587 | /* verify user access to buffer */ | |
588 | if (!access_ok(VERIFY_WRITE, buf, nr)) { | |
589 | printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user " | |
590 | "buffer\n", __FILE__, __LINE__); | |
591 | return -EFAULT; | |
592 | } | |
593 | ||
594 | for (;;) { | |
595 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
596 | return -EIO; | |
597 | ||
598 | n_hdlc = tty2n_hdlc (tty); | |
599 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || | |
600 | tty != n_hdlc->tty) | |
601 | return 0; | |
602 | ||
603 | rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
604 | if (rbuf) | |
605 | break; | |
606 | ||
607 | /* no data */ | |
608 | if (file->f_flags & O_NONBLOCK) | |
609 | return -EAGAIN; | |
610 | ||
611 | interruptible_sleep_on (&tty->read_wait); | |
612 | if (signal_pending(current)) | |
613 | return -EINTR; | |
614 | } | |
615 | ||
616 | if (rbuf->count > nr) | |
617 | /* frame too large for caller's buffer (discard frame) */ | |
618 | ret = -EOVERFLOW; | |
619 | else { | |
620 | /* Copy the data to the caller's buffer */ | |
621 | if (copy_to_user(buf, rbuf->buf, rbuf->count)) | |
622 | ret = -EFAULT; | |
623 | else | |
624 | ret = rbuf->count; | |
625 | } | |
626 | ||
627 | /* return HDLC buffer to free list unless the free list */ | |
628 | /* count has exceeded the default value, in which case the */ | |
629 | /* buffer is freed back to the OS to conserve memory */ | |
630 | if (n_hdlc->rx_free_buf_list.count > DEFAULT_RX_BUF_COUNT) | |
631 | kfree(rbuf); | |
632 | else | |
633 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,rbuf); | |
634 | ||
635 | return ret; | |
636 | ||
637 | } /* end of n_hdlc_tty_read() */ | |
638 | ||
639 | /** | |
640 | * n_hdlc_tty_write - write a single frame of data to device | |
641 | * @tty - pointer to associated tty device instance data | |
642 | * @file - pointer to file object data | |
643 | * @data - pointer to transmit data (one frame) | |
644 | * @count - size of transmit frame in bytes | |
645 | * | |
646 | * Returns the number of bytes written (or error code). | |
647 | */ | |
648 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
649 | const unsigned char *data, size_t count) | |
650 | { | |
651 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
652 | int error = 0; | |
653 | DECLARE_WAITQUEUE(wait, current); | |
654 | struct n_hdlc_buf *tbuf; | |
655 | ||
656 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
657 | printk("%s(%d)n_hdlc_tty_write() called count=%Zd\n", | |
658 | __FILE__,__LINE__,count); | |
659 | ||
660 | /* Verify pointers */ | |
661 | if (!n_hdlc) | |
662 | return -EIO; | |
663 | ||
664 | if (n_hdlc->magic != HDLC_MAGIC) | |
665 | return -EIO; | |
666 | ||
667 | /* verify frame size */ | |
668 | if (count > maxframe ) { | |
669 | if (debuglevel & DEBUG_LEVEL_INFO) | |
670 | printk (KERN_WARNING | |
671 | "n_hdlc_tty_write: truncating user packet " | |
672 | "from %lu to %d\n", (unsigned long) count, | |
673 | maxframe ); | |
674 | count = maxframe; | |
675 | } | |
676 | ||
677 | add_wait_queue(&tty->write_wait, &wait); | |
678 | set_current_state(TASK_INTERRUPTIBLE); | |
679 | ||
680 | /* Allocate transmit buffer */ | |
681 | /* sleep until transmit buffer available */ | |
682 | while (!(tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list))) { | |
683 | schedule(); | |
684 | ||
685 | n_hdlc = tty2n_hdlc (tty); | |
686 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || | |
687 | tty != n_hdlc->tty) { | |
688 | printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc); | |
689 | error = -EIO; | |
690 | break; | |
691 | } | |
692 | ||
693 | if (signal_pending(current)) { | |
694 | error = -EINTR; | |
695 | break; | |
696 | } | |
697 | } | |
698 | ||
699 | set_current_state(TASK_RUNNING); | |
700 | remove_wait_queue(&tty->write_wait, &wait); | |
701 | ||
702 | if (!error) { | |
703 | /* Retrieve the user's buffer */ | |
704 | memcpy(tbuf->buf, data, count); | |
705 | ||
706 | /* Send the data */ | |
707 | tbuf->count = error = count; | |
708 | n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf); | |
709 | n_hdlc_send_frames(n_hdlc,tty); | |
710 | } | |
711 | ||
712 | return error; | |
713 | ||
714 | } /* end of n_hdlc_tty_write() */ | |
715 | ||
716 | /** | |
717 | * n_hdlc_tty_ioctl - process IOCTL system call for the tty device. | |
718 | * @tty - pointer to tty instance data | |
719 | * @file - pointer to open file object for device | |
720 | * @cmd - IOCTL command code | |
721 | * @arg - argument for IOCTL call (cmd dependent) | |
722 | * | |
723 | * Returns command dependent result. | |
724 | */ | |
725 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
726 | unsigned int cmd, unsigned long arg) | |
727 | { | |
728 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
729 | int error = 0; | |
730 | int count; | |
731 | unsigned long flags; | |
732 | ||
733 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
734 | printk("%s(%d)n_hdlc_tty_ioctl() called %d\n", | |
735 | __FILE__,__LINE__,cmd); | |
736 | ||
737 | /* Verify the status of the device */ | |
738 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC) | |
739 | return -EBADF; | |
740 | ||
741 | switch (cmd) { | |
742 | case FIONREAD: | |
743 | /* report count of read data available */ | |
744 | /* in next available frame (if any) */ | |
745 | spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags); | |
746 | if (n_hdlc->rx_buf_list.head) | |
747 | count = n_hdlc->rx_buf_list.head->count; | |
748 | else | |
749 | count = 0; | |
750 | spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags); | |
751 | error = put_user(count, (int __user *)arg); | |
752 | break; | |
753 | ||
754 | case TIOCOUTQ: | |
755 | /* get the pending tx byte count in the driver */ | |
756 | count = tty->driver->chars_in_buffer ? | |
757 | tty->driver->chars_in_buffer(tty) : 0; | |
758 | /* add size of next output frame in queue */ | |
759 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags); | |
760 | if (n_hdlc->tx_buf_list.head) | |
761 | count += n_hdlc->tx_buf_list.head->count; | |
762 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags); | |
763 | error = put_user(count, (int __user *)arg); | |
764 | break; | |
765 | ||
766 | default: | |
767 | error = n_tty_ioctl (tty, file, cmd, arg); | |
768 | break; | |
769 | } | |
770 | return error; | |
771 | ||
772 | } /* end of n_hdlc_tty_ioctl() */ | |
773 | ||
774 | /** | |
775 | * n_hdlc_tty_poll - TTY callback for poll system call | |
776 | * @tty - pointer to tty instance data | |
777 | * @filp - pointer to open file object for device | |
778 | * @poll_table - wait queue for operations | |
779 | * | |
780 | * Determine which operations (read/write) will not block and return info | |
781 | * to caller. | |
782 | * Returns a bit mask containing info on which ops will not block. | |
783 | */ | |
784 | static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, | |
785 | poll_table *wait) | |
786 | { | |
787 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
788 | unsigned int mask = 0; | |
789 | ||
790 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
791 | printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__); | |
792 | ||
793 | if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) { | |
794 | /* queue current process into any wait queue that */ | |
795 | /* may awaken in the future (read and write) */ | |
796 | ||
797 | poll_wait(filp, &tty->read_wait, wait); | |
798 | poll_wait(filp, &tty->write_wait, wait); | |
799 | ||
800 | /* set bits for operations that won't block */ | |
801 | if(n_hdlc->rx_buf_list.head) | |
802 | mask |= POLLIN | POLLRDNORM; /* readable */ | |
803 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
804 | mask |= POLLHUP; | |
805 | if(tty_hung_up_p(filp)) | |
806 | mask |= POLLHUP; | |
807 | if(n_hdlc->tx_free_buf_list.head) | |
808 | mask |= POLLOUT | POLLWRNORM; /* writable */ | |
809 | } | |
810 | return mask; | |
811 | } /* end of n_hdlc_tty_poll() */ | |
812 | ||
813 | /** | |
814 | * n_hdlc_alloc - allocate an n_hdlc instance data structure | |
815 | * | |
816 | * Returns a pointer to newly created structure if success, otherwise %NULL | |
817 | */ | |
818 | static struct n_hdlc *n_hdlc_alloc(void) | |
819 | { | |
820 | struct n_hdlc_buf *buf; | |
821 | int i; | |
822 | struct n_hdlc *n_hdlc = kmalloc(sizeof(*n_hdlc), GFP_KERNEL); | |
823 | ||
824 | if (!n_hdlc) | |
825 | return NULL; | |
826 | ||
827 | memset(n_hdlc, 0, sizeof(*n_hdlc)); | |
828 | ||
829 | n_hdlc_buf_list_init(&n_hdlc->rx_free_buf_list); | |
830 | n_hdlc_buf_list_init(&n_hdlc->tx_free_buf_list); | |
831 | n_hdlc_buf_list_init(&n_hdlc->rx_buf_list); | |
832 | n_hdlc_buf_list_init(&n_hdlc->tx_buf_list); | |
833 | ||
834 | /* allocate free rx buffer list */ | |
835 | for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) { | |
836 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); | |
837 | if (buf) | |
838 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf); | |
839 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
840 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i); | |
841 | } | |
842 | ||
843 | /* allocate free tx buffer list */ | |
844 | for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) { | |
845 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); | |
846 | if (buf) | |
847 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf); | |
848 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
849 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i); | |
850 | } | |
851 | ||
852 | /* Initialize the control block */ | |
853 | n_hdlc->magic = HDLC_MAGIC; | |
854 | n_hdlc->flags = 0; | |
855 | ||
856 | return n_hdlc; | |
857 | ||
858 | } /* end of n_hdlc_alloc() */ | |
859 | ||
860 | /** | |
861 | * n_hdlc_buf_list_init - initialize specified HDLC buffer list | |
862 | * @list - pointer to buffer list | |
863 | */ | |
864 | static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list) | |
865 | { | |
866 | memset(list, 0, sizeof(*list)); | |
867 | spin_lock_init(&list->spinlock); | |
868 | } /* end of n_hdlc_buf_list_init() */ | |
869 | ||
870 | /** | |
871 | * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list | |
872 | * @list - pointer to buffer list | |
873 | * @buf - pointer to buffer | |
874 | */ | |
875 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, | |
876 | struct n_hdlc_buf *buf) | |
877 | { | |
878 | unsigned long flags; | |
879 | spin_lock_irqsave(&list->spinlock,flags); | |
880 | ||
881 | buf->link=NULL; | |
882 | if(list->tail) | |
883 | list->tail->link = buf; | |
884 | else | |
885 | list->head = buf; | |
886 | list->tail = buf; | |
887 | (list->count)++; | |
888 | ||
889 | spin_unlock_irqrestore(&list->spinlock,flags); | |
890 | ||
891 | } /* end of n_hdlc_buf_put() */ | |
892 | ||
893 | /** | |
894 | * n_hdlc_buf_get - remove and return an HDLC buffer from list | |
895 | * @list - pointer to HDLC buffer list | |
896 | * | |
897 | * Remove and return an HDLC buffer from the head of the specified HDLC buffer | |
898 | * list. | |
899 | * Returns a pointer to HDLC buffer if available, otherwise %NULL. | |
900 | */ | |
901 | static struct n_hdlc_buf* n_hdlc_buf_get(struct n_hdlc_buf_list *list) | |
902 | { | |
903 | unsigned long flags; | |
904 | struct n_hdlc_buf *buf; | |
905 | spin_lock_irqsave(&list->spinlock,flags); | |
906 | ||
907 | buf = list->head; | |
908 | if (buf) { | |
909 | list->head = buf->link; | |
910 | (list->count)--; | |
911 | } | |
912 | if (!list->head) | |
913 | list->tail = NULL; | |
914 | ||
915 | spin_unlock_irqrestore(&list->spinlock,flags); | |
916 | return buf; | |
917 | ||
918 | } /* end of n_hdlc_buf_get() */ | |
919 | ||
920 | static char hdlc_banner[] __initdata = | |
921 | KERN_INFO "HDLC line discipline: version " HDLC_VERSION | |
922 | ", maxframe=%u\n"; | |
923 | static char hdlc_register_ok[] __initdata = | |
924 | KERN_INFO "N_HDLC line discipline registered.\n"; | |
925 | static char hdlc_register_fail[] __initdata = | |
926 | KERN_ERR "error registering line discipline: %d\n"; | |
927 | static char hdlc_init_fail[] __initdata = | |
928 | KERN_INFO "N_HDLC: init failure %d\n"; | |
929 | ||
930 | static int __init n_hdlc_init(void) | |
931 | { | |
932 | int status; | |
933 | ||
934 | /* range check maxframe arg */ | |
935 | if (maxframe < 4096) | |
936 | maxframe = 4096; | |
937 | else if (maxframe > 65535) | |
938 | maxframe = 65535; | |
939 | ||
940 | printk(hdlc_banner, maxframe); | |
941 | ||
942 | status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc); | |
943 | if (!status) | |
944 | printk(hdlc_register_ok); | |
945 | else | |
946 | printk(hdlc_register_fail, status); | |
947 | ||
948 | if (status) | |
949 | printk(hdlc_init_fail, status); | |
950 | return status; | |
951 | ||
952 | } /* end of init_module() */ | |
953 | ||
954 | static char hdlc_unregister_ok[] __exitdata = | |
955 | KERN_INFO "N_HDLC: line discipline unregistered\n"; | |
956 | static char hdlc_unregister_fail[] __exitdata = | |
957 | KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n"; | |
958 | ||
959 | static void __exit n_hdlc_exit(void) | |
960 | { | |
961 | /* Release tty registration of line discipline */ | |
64ccd715 | 962 | int status = tty_unregister_ldisc(N_HDLC); |
1da177e4 LT |
963 | |
964 | if (status) | |
965 | printk(hdlc_unregister_fail, status); | |
966 | else | |
967 | printk(hdlc_unregister_ok); | |
968 | } | |
969 | ||
970 | module_init(n_hdlc_init); | |
971 | module_exit(n_hdlc_exit); | |
972 | ||
973 | MODULE_LICENSE("GPL"); | |
974 | MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com"); | |
975 | module_param(debuglevel, int, 0); | |
976 | module_param(maxframe, int, 0); | |
977 | MODULE_ALIAS_LDISC(N_HDLC); |