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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 | |
1da177e4 LT |
13 | * |
14 | * This code is released under the GNU General Public License (GPL) | |
15 | * | |
16 | * This module implements the tty line discipline N_HDLC for use with | |
17 | * tty device drivers that support bit-synchronous HDLC communications. | |
18 | * | |
19 | * All HDLC data is frame oriented which means: | |
20 | * | |
21 | * 1. tty write calls represent one complete transmit frame of data | |
22 | * The device driver should accept the complete frame or none of | |
23 | * the frame (busy) in the write method. Each write call should have | |
24 | * a byte count in the range of 2-65535 bytes (2 is min HDLC frame | |
25 | * with 1 addr byte and 1 ctrl byte). The max byte count of 65535 | |
26 | * should include any crc bytes required. For example, when using | |
27 | * CCITT CRC32, 4 crc bytes are required, so the maximum size frame | |
28 | * the application may transmit is limited to 65531 bytes. For CCITT | |
29 | * CRC16, the maximum application frame size would be 65533. | |
30 | * | |
31 | * | |
32 | * 2. receive callbacks from the device driver represents | |
33 | * one received frame. The device driver should bypass | |
34 | * the tty flip buffer and call the line discipline receive | |
35 | * callback directly to avoid fragmenting or concatenating | |
36 | * multiple frames into a single receive callback. | |
37 | * | |
38 | * The HDLC line discipline queues the receive frames in separate | |
39 | * buffers so complete receive frames can be returned by the | |
40 | * tty read calls. | |
41 | * | |
42 | * 3. tty read calls returns an entire frame of data or nothing. | |
43 | * | |
44 | * 4. all send and receive data is considered raw. No processing | |
45 | * or translation is performed by the line discipline, regardless | |
46 | * of the tty flags | |
47 | * | |
48 | * 5. When line discipline is queried for the amount of receive | |
49 | * data available (FIOC), 0 is returned if no data available, | |
50 | * otherwise the count of the next available frame is returned. | |
51 | * (instead of the sum of all received frame counts). | |
52 | * | |
53 | * These conventions allow the standard tty programming interface | |
54 | * to be used for synchronous HDLC applications when used with | |
55 | * this line discipline (or another line discipline that is frame | |
56 | * oriented such as N_PPP). | |
57 | * | |
58 | * The SyncLink driver (synclink.c) implements both asynchronous | |
59 | * (using standard line discipline N_TTY) and synchronous HDLC | |
60 | * (using N_HDLC) communications, with the latter using the above | |
61 | * conventions. | |
62 | * | |
63 | * This implementation is very basic and does not maintain | |
64 | * any statistics. The main point is to enforce the raw data | |
65 | * and frame orientation of HDLC communications. | |
66 | * | |
67 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED | |
68 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
69 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | |
70 | * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, | |
71 | * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
72 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | |
73 | * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
74 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
75 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
76 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
77 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
78 | */ | |
79 | ||
80 | #define HDLC_MAGIC 0x239e | |
1da177e4 | 81 | |
1da177e4 LT |
82 | #include <linux/module.h> |
83 | #include <linux/init.h> | |
84 | #include <linux/kernel.h> | |
85 | #include <linux/sched.h> | |
86 | #include <linux/types.h> | |
87 | #include <linux/fcntl.h> | |
88 | #include <linux/interrupt.h> | |
89 | #include <linux/ptrace.h> | |
90 | ||
91 | #undef VERSION | |
92 | #define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch)) | |
93 | ||
94 | #include <linux/poll.h> | |
95 | #include <linux/in.h> | |
96 | #include <linux/ioctl.h> | |
97 | #include <linux/slab.h> | |
98 | #include <linux/tty.h> | |
99 | #include <linux/errno.h> | |
100 | #include <linux/string.h> /* used in new tty drivers */ | |
101 | #include <linux/signal.h> /* used in new tty drivers */ | |
102 | #include <linux/if.h> | |
103 | #include <linux/bitops.h> | |
104 | ||
105 | #include <asm/system.h> | |
106 | #include <asm/termios.h> | |
107 | #include <asm/uaccess.h> | |
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 { | |
118 | struct n_hdlc_buf *link; | |
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 { | |
126 | struct n_hdlc_buf *head; | |
127 | struct n_hdlc_buf *tail; | |
128 | int count; | |
129 | spinlock_t spinlock; | |
130 | }; | |
131 | ||
132 | /** | |
133 | * struct n_hdlc - per device instance data structure | |
134 | * @magic - magic value for structure | |
135 | * @flags - miscellaneous control flags | |
136 | * @tty - ptr to TTY structure | |
137 | * @backup_tty - TTY to use if tty gets closed | |
138 | * @tbusy - reentrancy flag for tx wakeup code | |
139 | * @woke_up - FIXME: describe this field | |
140 | * @tbuf - currently transmitting tx buffer | |
141 | * @tx_buf_list - list of pending transmit frame buffers | |
142 | * @rx_buf_list - list of received frame buffers | |
143 | * @tx_free_buf_list - list unused transmit frame buffers | |
144 | * @rx_free_buf_list - list unused received frame buffers | |
145 | */ | |
146 | struct n_hdlc { | |
147 | int magic; | |
148 | __u32 flags; | |
149 | struct tty_struct *tty; | |
150 | struct tty_struct *backup_tty; | |
151 | int tbusy; | |
152 | int woke_up; | |
153 | struct n_hdlc_buf *tbuf; | |
154 | struct n_hdlc_buf_list tx_buf_list; | |
155 | struct n_hdlc_buf_list rx_buf_list; | |
156 | struct n_hdlc_buf_list tx_free_buf_list; | |
157 | struct n_hdlc_buf_list rx_free_buf_list; | |
158 | }; | |
159 | ||
160 | /* | |
161 | * HDLC buffer list manipulation functions | |
162 | */ | |
163 | static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list); | |
164 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, | |
165 | struct n_hdlc_buf *buf); | |
166 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list); | |
167 | ||
168 | /* Local functions */ | |
169 | ||
170 | static struct n_hdlc *n_hdlc_alloc (void); | |
171 | ||
172 | /* debug level can be set by insmod for debugging purposes */ | |
173 | #define DEBUG_LEVEL_INFO 1 | |
174 | static int debuglevel; | |
175 | ||
176 | /* max frame size for memory allocations */ | |
177 | static int maxframe = 4096; | |
178 | ||
179 | /* TTY callbacks */ | |
180 | ||
181 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
182 | __u8 __user *buf, size_t nr); | |
183 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
184 | const unsigned char *buf, size_t nr); | |
185 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
186 | unsigned int cmd, unsigned long arg); | |
187 | static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, | |
188 | poll_table *wait); | |
189 | static int n_hdlc_tty_open(struct tty_struct *tty); | |
190 | static void n_hdlc_tty_close(struct tty_struct *tty); | |
55db4c64 LT |
191 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp, |
192 | char *fp, int count); | |
1da177e4 LT |
193 | static void n_hdlc_tty_wakeup(struct tty_struct *tty); |
194 | ||
195 | #define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f))) | |
196 | ||
197 | #define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data)) | |
198 | #define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty) | |
199 | ||
be10eb75 PF |
200 | static void flush_rx_queue(struct tty_struct *tty) |
201 | { | |
202 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
203 | struct n_hdlc_buf *buf; | |
204 | ||
205 | while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list))) | |
206 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf); | |
207 | } | |
208 | ||
209 | static void flush_tx_queue(struct tty_struct *tty) | |
210 | { | |
211 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
212 | struct n_hdlc_buf *buf; | |
213 | unsigned long flags; | |
214 | ||
215 | while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list))) | |
216 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf); | |
217 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
218 | if (n_hdlc->tbuf) { | |
219 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, n_hdlc->tbuf); | |
220 | n_hdlc->tbuf = NULL; | |
221 | } | |
222 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
223 | } | |
224 | ||
a352def2 | 225 | static struct tty_ldisc_ops n_hdlc_ldisc = { |
1da177e4 LT |
226 | .owner = THIS_MODULE, |
227 | .magic = TTY_LDISC_MAGIC, | |
228 | .name = "hdlc", | |
229 | .open = n_hdlc_tty_open, | |
230 | .close = n_hdlc_tty_close, | |
231 | .read = n_hdlc_tty_read, | |
232 | .write = n_hdlc_tty_write, | |
233 | .ioctl = n_hdlc_tty_ioctl, | |
234 | .poll = n_hdlc_tty_poll, | |
235 | .receive_buf = n_hdlc_tty_receive, | |
1da177e4 | 236 | .write_wakeup = n_hdlc_tty_wakeup, |
be10eb75 | 237 | .flush_buffer = flush_rx_queue, |
1da177e4 LT |
238 | }; |
239 | ||
240 | /** | |
241 | * n_hdlc_release - release an n_hdlc per device line discipline info structure | |
242 | * @n_hdlc - per device line discipline info structure | |
243 | */ | |
244 | static void n_hdlc_release(struct n_hdlc *n_hdlc) | |
245 | { | |
246 | struct tty_struct *tty = n_hdlc2tty (n_hdlc); | |
247 | struct n_hdlc_buf *buf; | |
248 | ||
249 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
250 | printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__); | |
251 | ||
252 | /* Ensure that the n_hdlcd process is not hanging on select()/poll() */ | |
253 | wake_up_interruptible (&tty->read_wait); | |
254 | wake_up_interruptible (&tty->write_wait); | |
255 | ||
827afdf0 | 256 | if (tty->disc_data == n_hdlc) |
1da177e4 LT |
257 | tty->disc_data = NULL; /* Break the tty->n_hdlc link */ |
258 | ||
259 | /* Release transmit and receive buffers */ | |
260 | for(;;) { | |
261 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
262 | if (buf) { | |
263 | kfree(buf); | |
264 | } else | |
265 | break; | |
266 | } | |
267 | for(;;) { | |
268 | buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); | |
269 | if (buf) { | |
270 | kfree(buf); | |
271 | } else | |
272 | break; | |
273 | } | |
274 | for(;;) { | |
275 | buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
276 | if (buf) { | |
277 | kfree(buf); | |
278 | } else | |
279 | break; | |
280 | } | |
281 | for(;;) { | |
282 | buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
283 | if (buf) { | |
284 | kfree(buf); | |
285 | } else | |
286 | break; | |
287 | } | |
735d5661 | 288 | kfree(n_hdlc->tbuf); |
1da177e4 LT |
289 | kfree(n_hdlc); |
290 | ||
291 | } /* end of n_hdlc_release() */ | |
292 | ||
293 | /** | |
294 | * n_hdlc_tty_close - line discipline close | |
295 | * @tty - pointer to tty info structure | |
296 | * | |
297 | * Called when the line discipline is changed to something | |
298 | * else, the tty is closed, or the tty detects a hangup. | |
299 | */ | |
300 | static void n_hdlc_tty_close(struct tty_struct *tty) | |
301 | { | |
302 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
303 | ||
304 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
305 | printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__); | |
306 | ||
307 | if (n_hdlc != NULL) { | |
308 | if (n_hdlc->magic != HDLC_MAGIC) { | |
309 | printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n"); | |
310 | return; | |
311 | } | |
312 | #if defined(TTY_NO_WRITE_SPLIT) | |
313 | clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
314 | #endif | |
315 | tty->disc_data = NULL; | |
316 | if (tty == n_hdlc->backup_tty) | |
317 | n_hdlc->backup_tty = NULL; | |
318 | if (tty != n_hdlc->tty) | |
319 | return; | |
320 | if (n_hdlc->backup_tty) { | |
321 | n_hdlc->tty = n_hdlc->backup_tty; | |
322 | } else { | |
323 | n_hdlc_release (n_hdlc); | |
324 | } | |
325 | } | |
326 | ||
327 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
328 | printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__); | |
329 | ||
330 | } /* end of n_hdlc_tty_close() */ | |
331 | ||
332 | /** | |
333 | * n_hdlc_tty_open - called when line discipline changed to n_hdlc | |
334 | * @tty - pointer to tty info structure | |
335 | * | |
336 | * Returns 0 if success, otherwise error code | |
337 | */ | |
338 | static int n_hdlc_tty_open (struct tty_struct *tty) | |
339 | { | |
340 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
341 | ||
342 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
343 | printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n", | |
344 | __FILE__,__LINE__, | |
345 | tty->name); | |
346 | ||
347 | /* There should not be an existing table for this slot. */ | |
348 | if (n_hdlc) { | |
349 | printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" ); | |
350 | return -EEXIST; | |
351 | } | |
352 | ||
353 | n_hdlc = n_hdlc_alloc(); | |
354 | if (!n_hdlc) { | |
355 | printk (KERN_ERR "n_hdlc_alloc failed\n"); | |
356 | return -ENFILE; | |
357 | } | |
358 | ||
359 | tty->disc_data = n_hdlc; | |
360 | n_hdlc->tty = tty; | |
33f0f88f | 361 | tty->receive_room = 65536; |
1da177e4 LT |
362 | |
363 | #if defined(TTY_NO_WRITE_SPLIT) | |
364 | /* change tty_io write() to not split large writes into 8K chunks */ | |
365 | set_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
366 | #endif | |
367 | ||
be10eb75 | 368 | /* flush receive data from driver */ |
f34d7a5b | 369 | tty_driver_flush_buffer(tty); |
1da177e4 LT |
370 | |
371 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
372 | printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__); | |
373 | ||
374 | return 0; | |
375 | ||
376 | } /* end of n_tty_hdlc_open() */ | |
377 | ||
378 | /** | |
379 | * n_hdlc_send_frames - send frames on pending send buffer list | |
380 | * @n_hdlc - pointer to ldisc instance data | |
381 | * @tty - pointer to tty instance data | |
382 | * | |
383 | * Send frames on pending send buffer list until the driver does not accept a | |
384 | * frame (busy) this function is called after adding a frame to the send buffer | |
385 | * list and by the tty wakeup callback. | |
386 | */ | |
387 | static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) | |
388 | { | |
389 | register int actual; | |
390 | unsigned long flags; | |
391 | struct n_hdlc_buf *tbuf; | |
392 | ||
393 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
394 | printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__); | |
395 | check_again: | |
396 | ||
397 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
398 | if (n_hdlc->tbusy) { | |
399 | n_hdlc->woke_up = 1; | |
400 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
401 | return; | |
402 | } | |
403 | n_hdlc->tbusy = 1; | |
404 | n_hdlc->woke_up = 0; | |
405 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
406 | ||
407 | /* get current transmit buffer or get new transmit */ | |
408 | /* buffer from list of pending transmit buffers */ | |
409 | ||
410 | tbuf = n_hdlc->tbuf; | |
411 | if (!tbuf) | |
412 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
413 | ||
414 | while (tbuf) { | |
415 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
416 | printk("%s(%d)sending frame %p, count=%d\n", | |
417 | __FILE__,__LINE__,tbuf,tbuf->count); | |
418 | ||
419 | /* Send the next block of data to device */ | |
420 | tty->flags |= (1 << TTY_DO_WRITE_WAKEUP); | |
f34d7a5b | 421 | actual = tty->ops->write(tty, tbuf->buf, tbuf->count); |
b0fed314 JS |
422 | |
423 | /* rollback was possible and has been done */ | |
424 | if (actual == -ERESTARTSYS) { | |
425 | n_hdlc->tbuf = tbuf; | |
426 | break; | |
427 | } | |
1da177e4 LT |
428 | /* if transmit error, throw frame away by */ |
429 | /* pretending it was accepted by driver */ | |
430 | if (actual < 0) | |
431 | actual = tbuf->count; | |
432 | ||
433 | if (actual == tbuf->count) { | |
434 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
435 | printk("%s(%d)frame %p completed\n", | |
436 | __FILE__,__LINE__,tbuf); | |
437 | ||
438 | /* free current transmit buffer */ | |
439 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf); | |
440 | ||
441 | /* this tx buffer is done */ | |
442 | n_hdlc->tbuf = NULL; | |
443 | ||
444 | /* wait up sleeping writers */ | |
445 | wake_up_interruptible(&tty->write_wait); | |
446 | ||
447 | /* get next pending transmit buffer */ | |
448 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
449 | } else { | |
450 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
451 | printk("%s(%d)frame %p pending\n", | |
452 | __FILE__,__LINE__,tbuf); | |
453 | ||
454 | /* buffer not accepted by driver */ | |
455 | /* set this buffer as pending buffer */ | |
456 | n_hdlc->tbuf = tbuf; | |
457 | break; | |
458 | } | |
459 | } | |
460 | ||
461 | if (!tbuf) | |
462 | tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP); | |
463 | ||
464 | /* Clear the re-entry flag */ | |
465 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
466 | n_hdlc->tbusy = 0; | |
467 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
468 | ||
469 | if (n_hdlc->woke_up) | |
470 | goto check_again; | |
471 | ||
472 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
473 | printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__); | |
474 | ||
475 | } /* end of n_hdlc_send_frames() */ | |
476 | ||
477 | /** | |
478 | * n_hdlc_tty_wakeup - Callback for transmit wakeup | |
479 | * @tty - pointer to associated tty instance data | |
480 | * | |
481 | * Called when low level device driver can accept more send data. | |
482 | */ | |
483 | static void n_hdlc_tty_wakeup(struct tty_struct *tty) | |
484 | { | |
485 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
486 | ||
487 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
488 | printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__); | |
489 | ||
490 | if (!n_hdlc) | |
491 | return; | |
492 | ||
493 | if (tty != n_hdlc->tty) { | |
494 | tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP); | |
495 | return; | |
496 | } | |
497 | ||
498 | n_hdlc_send_frames (n_hdlc, tty); | |
499 | ||
500 | } /* end of n_hdlc_tty_wakeup() */ | |
501 | ||
1da177e4 LT |
502 | /** |
503 | * n_hdlc_tty_receive - Called by tty driver when receive data is available | |
504 | * @tty - pointer to tty instance data | |
505 | * @data - pointer to received data | |
506 | * @flags - pointer to flags for data | |
507 | * @count - count of received data in bytes | |
508 | * | |
509 | * Called by tty low level driver when receive data is available. Data is | |
510 | * interpreted as one HDLC frame. | |
511 | */ | |
55db4c64 LT |
512 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data, |
513 | char *flags, int count) | |
1da177e4 LT |
514 | { |
515 | register struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
516 | register struct n_hdlc_buf *buf; | |
517 | ||
518 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
519 | printk("%s(%d)n_hdlc_tty_receive() called count=%d\n", | |
520 | __FILE__,__LINE__, count); | |
521 | ||
522 | /* This can happen if stuff comes in on the backup tty */ | |
a01e035e | 523 | if (!n_hdlc || tty != n_hdlc->tty) |
55db4c64 | 524 | return; |
1da177e4 LT |
525 | |
526 | /* verify line is using HDLC discipline */ | |
527 | if (n_hdlc->magic != HDLC_MAGIC) { | |
528 | printk("%s(%d) line not using HDLC discipline\n", | |
529 | __FILE__,__LINE__); | |
55db4c64 | 530 | return; |
1da177e4 LT |
531 | } |
532 | ||
533 | if ( count>maxframe ) { | |
534 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
535 | printk("%s(%d) rx count>maxframesize, data discarded\n", | |
536 | __FILE__,__LINE__); | |
55db4c64 | 537 | return; |
1da177e4 LT |
538 | } |
539 | ||
540 | /* get a free HDLC buffer */ | |
541 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
542 | if (!buf) { | |
543 | /* no buffers in free list, attempt to allocate another rx buffer */ | |
544 | /* unless the maximum count has been reached */ | |
545 | if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT) | |
546 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC); | |
547 | } | |
548 | ||
549 | if (!buf) { | |
550 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
551 | printk("%s(%d) no more rx buffers, data discarded\n", | |
552 | __FILE__,__LINE__); | |
55db4c64 | 553 | return; |
1da177e4 LT |
554 | } |
555 | ||
556 | /* copy received data to HDLC buffer */ | |
557 | memcpy(buf->buf,data,count); | |
558 | buf->count=count; | |
559 | ||
560 | /* add HDLC buffer to list of received frames */ | |
561 | n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf); | |
562 | ||
563 | /* wake up any blocked reads and perform async signalling */ | |
564 | wake_up_interruptible (&tty->read_wait); | |
565 | if (n_hdlc->tty->fasync != NULL) | |
566 | kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN); | |
567 | ||
568 | } /* end of n_hdlc_tty_receive() */ | |
569 | ||
570 | /** | |
4a4efbde | 571 | * n_hdlc_tty_read - Called to retrieve one frame of data (if available) |
1da177e4 LT |
572 | * @tty - pointer to tty instance data |
573 | * @file - pointer to open file object | |
574 | * @buf - pointer to returned data buffer | |
575 | * @nr - size of returned data buffer | |
576 | * | |
577 | * Returns the number of bytes returned or error code. | |
578 | */ | |
579 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
580 | __u8 __user *buf, size_t nr) | |
581 | { | |
582 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
1035b63d | 583 | int ret = 0; |
1da177e4 | 584 | struct n_hdlc_buf *rbuf; |
1035b63d | 585 | DECLARE_WAITQUEUE(wait, current); |
1da177e4 LT |
586 | |
587 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
588 | printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__); | |
589 | ||
590 | /* Validate the pointers */ | |
591 | if (!n_hdlc) | |
592 | return -EIO; | |
593 | ||
594 | /* verify user access to buffer */ | |
595 | if (!access_ok(VERIFY_WRITE, buf, nr)) { | |
596 | printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user " | |
597 | "buffer\n", __FILE__, __LINE__); | |
598 | return -EFAULT; | |
599 | } | |
600 | ||
1035b63d | 601 | add_wait_queue(&tty->read_wait, &wait); |
04f378b1 | 602 | |
1da177e4 | 603 | for (;;) { |
04f378b1 | 604 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { |
1035b63d PF |
605 | ret = -EIO; |
606 | break; | |
04f378b1 | 607 | } |
1035b63d PF |
608 | if (tty_hung_up_p(file)) |
609 | break; | |
1da177e4 | 610 | |
1035b63d | 611 | set_current_state(TASK_INTERRUPTIBLE); |
1da177e4 LT |
612 | |
613 | rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
1035b63d PF |
614 | if (rbuf) { |
615 | if (rbuf->count > nr) { | |
616 | /* too large for caller's buffer */ | |
617 | ret = -EOVERFLOW; | |
618 | } else { | |
619 | if (copy_to_user(buf, rbuf->buf, rbuf->count)) | |
620 | ret = -EFAULT; | |
621 | else | |
622 | ret = rbuf->count; | |
623 | } | |
624 | ||
625 | if (n_hdlc->rx_free_buf_list.count > | |
626 | DEFAULT_RX_BUF_COUNT) | |
627 | kfree(rbuf); | |
628 | else | |
629 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf); | |
1da177e4 | 630 | break; |
1035b63d | 631 | } |
1da177e4 LT |
632 | |
633 | /* no data */ | |
04f378b1 | 634 | if (file->f_flags & O_NONBLOCK) { |
1035b63d PF |
635 | ret = -EAGAIN; |
636 | break; | |
04f378b1 | 637 | } |
1035b63d PF |
638 | |
639 | schedule(); | |
640 | ||
04f378b1 | 641 | if (signal_pending(current)) { |
1035b63d PF |
642 | ret = -EINTR; |
643 | break; | |
04f378b1 | 644 | } |
1da177e4 | 645 | } |
1035b63d PF |
646 | |
647 | remove_wait_queue(&tty->read_wait, &wait); | |
648 | __set_current_state(TASK_RUNNING); | |
649 | ||
1da177e4 LT |
650 | return ret; |
651 | ||
652 | } /* end of n_hdlc_tty_read() */ | |
653 | ||
654 | /** | |
655 | * n_hdlc_tty_write - write a single frame of data to device | |
656 | * @tty - pointer to associated tty device instance data | |
657 | * @file - pointer to file object data | |
658 | * @data - pointer to transmit data (one frame) | |
659 | * @count - size of transmit frame in bytes | |
660 | * | |
661 | * Returns the number of bytes written (or error code). | |
662 | */ | |
663 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
664 | const unsigned char *data, size_t count) | |
665 | { | |
666 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
667 | int error = 0; | |
668 | DECLARE_WAITQUEUE(wait, current); | |
669 | struct n_hdlc_buf *tbuf; | |
670 | ||
671 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
672 | printk("%s(%d)n_hdlc_tty_write() called count=%Zd\n", | |
673 | __FILE__,__LINE__,count); | |
674 | ||
675 | /* Verify pointers */ | |
676 | if (!n_hdlc) | |
677 | return -EIO; | |
678 | ||
679 | if (n_hdlc->magic != HDLC_MAGIC) | |
680 | return -EIO; | |
681 | ||
682 | /* verify frame size */ | |
683 | if (count > maxframe ) { | |
684 | if (debuglevel & DEBUG_LEVEL_INFO) | |
685 | printk (KERN_WARNING | |
686 | "n_hdlc_tty_write: truncating user packet " | |
687 | "from %lu to %d\n", (unsigned long) count, | |
688 | maxframe ); | |
689 | count = maxframe; | |
690 | } | |
691 | ||
692 | add_wait_queue(&tty->write_wait, &wait); | |
1035b63d PF |
693 | |
694 | for (;;) { | |
695 | set_current_state(TASK_INTERRUPTIBLE); | |
1da177e4 | 696 | |
1035b63d PF |
697 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); |
698 | if (tbuf) | |
699 | break; | |
700 | ||
c72f527c PF |
701 | if (file->f_flags & O_NONBLOCK) { |
702 | error = -EAGAIN; | |
703 | break; | |
704 | } | |
1da177e4 LT |
705 | schedule(); |
706 | ||
707 | n_hdlc = tty2n_hdlc (tty); | |
708 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || | |
709 | tty != n_hdlc->tty) { | |
710 | printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc); | |
711 | error = -EIO; | |
712 | break; | |
713 | } | |
714 | ||
715 | if (signal_pending(current)) { | |
716 | error = -EINTR; | |
717 | break; | |
718 | } | |
719 | } | |
720 | ||
1035b63d | 721 | __set_current_state(TASK_RUNNING); |
1da177e4 LT |
722 | remove_wait_queue(&tty->write_wait, &wait); |
723 | ||
724 | if (!error) { | |
725 | /* Retrieve the user's buffer */ | |
726 | memcpy(tbuf->buf, data, count); | |
727 | ||
728 | /* Send the data */ | |
729 | tbuf->count = error = count; | |
730 | n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf); | |
731 | n_hdlc_send_frames(n_hdlc,tty); | |
732 | } | |
1035b63d | 733 | |
1da177e4 LT |
734 | return error; |
735 | ||
736 | } /* end of n_hdlc_tty_write() */ | |
737 | ||
738 | /** | |
739 | * n_hdlc_tty_ioctl - process IOCTL system call for the tty device. | |
740 | * @tty - pointer to tty instance data | |
741 | * @file - pointer to open file object for device | |
742 | * @cmd - IOCTL command code | |
743 | * @arg - argument for IOCTL call (cmd dependent) | |
744 | * | |
745 | * Returns command dependent result. | |
746 | */ | |
747 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
748 | unsigned int cmd, unsigned long arg) | |
749 | { | |
750 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
751 | int error = 0; | |
752 | int count; | |
753 | unsigned long flags; | |
754 | ||
755 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
756 | printk("%s(%d)n_hdlc_tty_ioctl() called %d\n", | |
757 | __FILE__,__LINE__,cmd); | |
758 | ||
759 | /* Verify the status of the device */ | |
760 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC) | |
761 | return -EBADF; | |
762 | ||
763 | switch (cmd) { | |
764 | case FIONREAD: | |
765 | /* report count of read data available */ | |
766 | /* in next available frame (if any) */ | |
767 | spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags); | |
768 | if (n_hdlc->rx_buf_list.head) | |
769 | count = n_hdlc->rx_buf_list.head->count; | |
770 | else | |
771 | count = 0; | |
772 | spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags); | |
773 | error = put_user(count, (int __user *)arg); | |
774 | break; | |
775 | ||
776 | case TIOCOUTQ: | |
777 | /* get the pending tx byte count in the driver */ | |
f34d7a5b | 778 | count = tty_chars_in_buffer(tty); |
1da177e4 LT |
779 | /* add size of next output frame in queue */ |
780 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags); | |
781 | if (n_hdlc->tx_buf_list.head) | |
782 | count += n_hdlc->tx_buf_list.head->count; | |
783 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags); | |
784 | error = put_user(count, (int __user *)arg); | |
785 | break; | |
786 | ||
be10eb75 PF |
787 | case TCFLSH: |
788 | switch (arg) { | |
789 | case TCIOFLUSH: | |
790 | case TCOFLUSH: | |
791 | flush_tx_queue(tty); | |
792 | } | |
793 | /* fall through to default */ | |
794 | ||
1da177e4 | 795 | default: |
47afa7a5 | 796 | error = n_tty_ioctl_helper(tty, file, cmd, arg); |
1da177e4 LT |
797 | break; |
798 | } | |
799 | return error; | |
800 | ||
801 | } /* end of n_hdlc_tty_ioctl() */ | |
802 | ||
803 | /** | |
804 | * n_hdlc_tty_poll - TTY callback for poll system call | |
805 | * @tty - pointer to tty instance data | |
806 | * @filp - pointer to open file object for device | |
807 | * @poll_table - wait queue for operations | |
808 | * | |
809 | * Determine which operations (read/write) will not block and return info | |
810 | * to caller. | |
811 | * Returns a bit mask containing info on which ops will not block. | |
812 | */ | |
813 | static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, | |
814 | poll_table *wait) | |
815 | { | |
816 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
817 | unsigned int mask = 0; | |
818 | ||
819 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
820 | printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__); | |
821 | ||
822 | if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) { | |
823 | /* queue current process into any wait queue that */ | |
824 | /* may awaken in the future (read and write) */ | |
825 | ||
826 | poll_wait(filp, &tty->read_wait, wait); | |
827 | poll_wait(filp, &tty->write_wait, wait); | |
828 | ||
829 | /* set bits for operations that won't block */ | |
9c1729db | 830 | if (n_hdlc->rx_buf_list.head) |
1da177e4 LT |
831 | mask |= POLLIN | POLLRDNORM; /* readable */ |
832 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
833 | mask |= POLLHUP; | |
9c1729db | 834 | if (tty_hung_up_p(filp)) |
1da177e4 | 835 | mask |= POLLHUP; |
9c1729db AC |
836 | if (!tty_is_writelocked(tty) && |
837 | n_hdlc->tx_free_buf_list.head) | |
1da177e4 LT |
838 | mask |= POLLOUT | POLLWRNORM; /* writable */ |
839 | } | |
840 | return mask; | |
841 | } /* end of n_hdlc_tty_poll() */ | |
842 | ||
843 | /** | |
844 | * n_hdlc_alloc - allocate an n_hdlc instance data structure | |
845 | * | |
846 | * Returns a pointer to newly created structure if success, otherwise %NULL | |
847 | */ | |
848 | static struct n_hdlc *n_hdlc_alloc(void) | |
849 | { | |
850 | struct n_hdlc_buf *buf; | |
851 | int i; | |
852 | struct n_hdlc *n_hdlc = kmalloc(sizeof(*n_hdlc), GFP_KERNEL); | |
853 | ||
854 | if (!n_hdlc) | |
855 | return NULL; | |
856 | ||
857 | memset(n_hdlc, 0, sizeof(*n_hdlc)); | |
858 | ||
859 | n_hdlc_buf_list_init(&n_hdlc->rx_free_buf_list); | |
860 | n_hdlc_buf_list_init(&n_hdlc->tx_free_buf_list); | |
861 | n_hdlc_buf_list_init(&n_hdlc->rx_buf_list); | |
862 | n_hdlc_buf_list_init(&n_hdlc->tx_buf_list); | |
863 | ||
864 | /* allocate free rx buffer list */ | |
865 | for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) { | |
866 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); | |
867 | if (buf) | |
868 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf); | |
869 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
870 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i); | |
871 | } | |
872 | ||
873 | /* allocate free tx buffer list */ | |
874 | for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) { | |
875 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); | |
876 | if (buf) | |
877 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf); | |
878 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
879 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i); | |
880 | } | |
881 | ||
882 | /* Initialize the control block */ | |
883 | n_hdlc->magic = HDLC_MAGIC; | |
884 | n_hdlc->flags = 0; | |
885 | ||
886 | return n_hdlc; | |
887 | ||
888 | } /* end of n_hdlc_alloc() */ | |
889 | ||
890 | /** | |
891 | * n_hdlc_buf_list_init - initialize specified HDLC buffer list | |
892 | * @list - pointer to buffer list | |
893 | */ | |
894 | static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list) | |
895 | { | |
896 | memset(list, 0, sizeof(*list)); | |
897 | spin_lock_init(&list->spinlock); | |
898 | } /* end of n_hdlc_buf_list_init() */ | |
899 | ||
900 | /** | |
901 | * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list | |
902 | * @list - pointer to buffer list | |
903 | * @buf - pointer to buffer | |
904 | */ | |
905 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, | |
906 | struct n_hdlc_buf *buf) | |
907 | { | |
908 | unsigned long flags; | |
909 | spin_lock_irqsave(&list->spinlock,flags); | |
910 | ||
911 | buf->link=NULL; | |
9c1729db | 912 | if (list->tail) |
1da177e4 LT |
913 | list->tail->link = buf; |
914 | else | |
915 | list->head = buf; | |
916 | list->tail = buf; | |
917 | (list->count)++; | |
918 | ||
919 | spin_unlock_irqrestore(&list->spinlock,flags); | |
920 | ||
921 | } /* end of n_hdlc_buf_put() */ | |
922 | ||
923 | /** | |
924 | * n_hdlc_buf_get - remove and return an HDLC buffer from list | |
925 | * @list - pointer to HDLC buffer list | |
926 | * | |
927 | * Remove and return an HDLC buffer from the head of the specified HDLC buffer | |
928 | * list. | |
929 | * Returns a pointer to HDLC buffer if available, otherwise %NULL. | |
930 | */ | |
931 | static struct n_hdlc_buf* n_hdlc_buf_get(struct n_hdlc_buf_list *list) | |
932 | { | |
933 | unsigned long flags; | |
934 | struct n_hdlc_buf *buf; | |
935 | spin_lock_irqsave(&list->spinlock,flags); | |
936 | ||
937 | buf = list->head; | |
938 | if (buf) { | |
939 | list->head = buf->link; | |
940 | (list->count)--; | |
941 | } | |
942 | if (!list->head) | |
943 | list->tail = NULL; | |
944 | ||
945 | spin_unlock_irqrestore(&list->spinlock,flags); | |
946 | return buf; | |
947 | ||
948 | } /* end of n_hdlc_buf_get() */ | |
949 | ||
950 | static char hdlc_banner[] __initdata = | |
be10eb75 | 951 | KERN_INFO "HDLC line discipline maxframe=%u\n"; |
1da177e4 LT |
952 | static char hdlc_register_ok[] __initdata = |
953 | KERN_INFO "N_HDLC line discipline registered.\n"; | |
954 | static char hdlc_register_fail[] __initdata = | |
955 | KERN_ERR "error registering line discipline: %d\n"; | |
956 | static char hdlc_init_fail[] __initdata = | |
957 | KERN_INFO "N_HDLC: init failure %d\n"; | |
958 | ||
959 | static int __init n_hdlc_init(void) | |
960 | { | |
961 | int status; | |
962 | ||
963 | /* range check maxframe arg */ | |
964 | if (maxframe < 4096) | |
965 | maxframe = 4096; | |
966 | else if (maxframe > 65535) | |
967 | maxframe = 65535; | |
968 | ||
969 | printk(hdlc_banner, maxframe); | |
970 | ||
971 | status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc); | |
972 | if (!status) | |
973 | printk(hdlc_register_ok); | |
974 | else | |
975 | printk(hdlc_register_fail, status); | |
976 | ||
977 | if (status) | |
978 | printk(hdlc_init_fail, status); | |
979 | return status; | |
980 | ||
981 | } /* end of init_module() */ | |
982 | ||
983 | static char hdlc_unregister_ok[] __exitdata = | |
984 | KERN_INFO "N_HDLC: line discipline unregistered\n"; | |
985 | static char hdlc_unregister_fail[] __exitdata = | |
986 | KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n"; | |
987 | ||
988 | static void __exit n_hdlc_exit(void) | |
989 | { | |
990 | /* Release tty registration of line discipline */ | |
64ccd715 | 991 | int status = tty_unregister_ldisc(N_HDLC); |
1da177e4 LT |
992 | |
993 | if (status) | |
994 | printk(hdlc_unregister_fail, status); | |
995 | else | |
996 | printk(hdlc_unregister_ok); | |
997 | } | |
998 | ||
999 | module_init(n_hdlc_init); | |
1000 | module_exit(n_hdlc_exit); | |
1001 | ||
1002 | MODULE_LICENSE("GPL"); | |
1003 | MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com"); | |
1004 | module_param(debuglevel, int, 0); | |
1005 | module_param(maxframe, int, 0); | |
1006 | MODULE_ALIAS_LDISC(N_HDLC); |