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