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e3b3d0f5 | 1 | // SPDX-License-Identifier: GPL-1.0+ |
1da177e4 LT |
2 | /* generic HDLC line discipline for Linux |
3 | * | |
4 | * Written by Paul Fulghum paulkf@microgate.com | |
5 | * for Microgate Corporation | |
6 | * | |
7 | * Microgate and SyncLink are registered trademarks of Microgate Corporation | |
8 | * | |
9 | * Adapted from ppp.c, written by Michael Callahan <callahan@maths.ox.ac.uk>, | |
10 | * Al Longyear <longyear@netcom.com>, | |
11 | * Paul Mackerras <Paul.Mackerras@cs.anu.edu.au> | |
12 | * | |
13 | * Original release 01/11/99 | |
1da177e4 | 14 | * |
1da177e4 LT |
15 | * This module implements the tty line discipline N_HDLC for use with |
16 | * tty device drivers that support bit-synchronous HDLC communications. | |
17 | * | |
18 | * All HDLC data is frame oriented which means: | |
19 | * | |
20 | * 1. tty write calls represent one complete transmit frame of data | |
21 | * The device driver should accept the complete frame or none of | |
22 | * the frame (busy) in the write method. Each write call should have | |
23 | * a byte count in the range of 2-65535 bytes (2 is min HDLC frame | |
24 | * with 1 addr byte and 1 ctrl byte). The max byte count of 65535 | |
25 | * should include any crc bytes required. For example, when using | |
26 | * CCITT CRC32, 4 crc bytes are required, so the maximum size frame | |
27 | * the application may transmit is limited to 65531 bytes. For CCITT | |
28 | * CRC16, the maximum application frame size would be 65533. | |
29 | * | |
30 | * | |
31 | * 2. receive callbacks from the device driver represents | |
32 | * one received frame. The device driver should bypass | |
33 | * the tty flip buffer and call the line discipline receive | |
34 | * callback directly to avoid fragmenting or concatenating | |
35 | * multiple frames into a single receive callback. | |
36 | * | |
37 | * The HDLC line discipline queues the receive frames in separate | |
38 | * buffers so complete receive frames can be returned by the | |
39 | * tty read calls. | |
40 | * | |
41 | * 3. tty read calls returns an entire frame of data or nothing. | |
42 | * | |
43 | * 4. all send and receive data is considered raw. No processing | |
44 | * or translation is performed by the line discipline, regardless | |
45 | * of the tty flags | |
46 | * | |
47 | * 5. When line discipline is queried for the amount of receive | |
48 | * data available (FIOC), 0 is returned if no data available, | |
49 | * otherwise the count of the next available frame is returned. | |
50 | * (instead of the sum of all received frame counts). | |
51 | * | |
52 | * These conventions allow the standard tty programming interface | |
53 | * to be used for synchronous HDLC applications when used with | |
54 | * this line discipline (or another line discipline that is frame | |
55 | * oriented such as N_PPP). | |
56 | * | |
57 | * The SyncLink driver (synclink.c) implements both asynchronous | |
58 | * (using standard line discipline N_TTY) and synchronous HDLC | |
59 | * (using N_HDLC) communications, with the latter using the above | |
60 | * conventions. | |
61 | * | |
62 | * This implementation is very basic and does not maintain | |
63 | * any statistics. The main point is to enforce the raw data | |
64 | * and frame orientation of HDLC communications. | |
65 | * | |
66 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED | |
67 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
68 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | |
69 | * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, | |
70 | * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
71 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | |
72 | * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
73 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
74 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
75 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
76 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
77 | */ | |
78 | ||
79 | #define HDLC_MAGIC 0x239e | |
1da177e4 | 80 | |
1da177e4 LT |
81 | #include <linux/module.h> |
82 | #include <linux/init.h> | |
83 | #include <linux/kernel.h> | |
84 | #include <linux/sched.h> | |
85 | #include <linux/types.h> | |
86 | #include <linux/fcntl.h> | |
87 | #include <linux/interrupt.h> | |
88 | #include <linux/ptrace.h> | |
89 | ||
1da177e4 LT |
90 | #include <linux/poll.h> |
91 | #include <linux/in.h> | |
92 | #include <linux/ioctl.h> | |
93 | #include <linux/slab.h> | |
94 | #include <linux/tty.h> | |
95 | #include <linux/errno.h> | |
96 | #include <linux/string.h> /* used in new tty drivers */ | |
97 | #include <linux/signal.h> /* used in new tty drivers */ | |
98 | #include <linux/if.h> | |
99 | #include <linux/bitops.h> | |
100 | ||
1da177e4 | 101 | #include <asm/termios.h> |
7c0f6ba6 | 102 | #include <linux/uaccess.h> |
1da177e4 LT |
103 | |
104 | /* | |
105 | * Buffers for individual HDLC frames | |
106 | */ | |
107 | #define MAX_HDLC_FRAME_SIZE 65535 | |
108 | #define DEFAULT_RX_BUF_COUNT 10 | |
109 | #define MAX_RX_BUF_COUNT 60 | |
be10eb75 | 110 | #define DEFAULT_TX_BUF_COUNT 3 |
1da177e4 LT |
111 | |
112 | struct n_hdlc_buf { | |
82f2341c | 113 | struct list_head list_item; |
1da177e4 | 114 | int count; |
85f4c951 | 115 | char buf[]; |
1da177e4 LT |
116 | }; |
117 | ||
1da177e4 | 118 | struct n_hdlc_buf_list { |
82f2341c | 119 | struct list_head list; |
1da177e4 LT |
120 | int count; |
121 | spinlock_t spinlock; | |
122 | }; | |
123 | ||
124 | /** | |
125 | * struct n_hdlc - per device instance data structure | |
126 | * @magic - magic value for structure | |
127 | * @flags - miscellaneous control flags | |
128 | * @tty - ptr to TTY structure | |
129 | * @backup_tty - TTY to use if tty gets closed | |
130 | * @tbusy - reentrancy flag for tx wakeup code | |
131 | * @woke_up - FIXME: describe this field | |
1da177e4 LT |
132 | * @tx_buf_list - list of pending transmit frame buffers |
133 | * @rx_buf_list - list of received frame buffers | |
134 | * @tx_free_buf_list - list unused transmit frame buffers | |
135 | * @rx_free_buf_list - list unused received frame buffers | |
136 | */ | |
137 | struct n_hdlc { | |
138 | int magic; | |
139 | __u32 flags; | |
140 | struct tty_struct *tty; | |
141 | struct tty_struct *backup_tty; | |
142 | int tbusy; | |
143 | int woke_up; | |
1da177e4 LT |
144 | struct n_hdlc_buf_list tx_buf_list; |
145 | struct n_hdlc_buf_list rx_buf_list; | |
146 | struct n_hdlc_buf_list tx_free_buf_list; | |
147 | struct n_hdlc_buf_list rx_free_buf_list; | |
148 | }; | |
149 | ||
150 | /* | |
151 | * HDLC buffer list manipulation functions | |
152 | */ | |
82f2341c AP |
153 | static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, |
154 | struct n_hdlc_buf *buf); | |
1da177e4 LT |
155 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, |
156 | struct n_hdlc_buf *buf); | |
157 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list); | |
158 | ||
159 | /* Local functions */ | |
160 | ||
161 | static struct n_hdlc *n_hdlc_alloc (void); | |
162 | ||
163 | /* debug level can be set by insmod for debugging purposes */ | |
164 | #define DEBUG_LEVEL_INFO 1 | |
165 | static int debuglevel; | |
166 | ||
167 | /* max frame size for memory allocations */ | |
168 | static int maxframe = 4096; | |
169 | ||
170 | /* TTY callbacks */ | |
171 | ||
172 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
173 | __u8 __user *buf, size_t nr); | |
174 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
175 | const unsigned char *buf, size_t nr); | |
176 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
177 | unsigned int cmd, unsigned long arg); | |
afc9a42b | 178 | static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, |
1da177e4 LT |
179 | poll_table *wait); |
180 | static int n_hdlc_tty_open(struct tty_struct *tty); | |
181 | static void n_hdlc_tty_close(struct tty_struct *tty); | |
55db4c64 LT |
182 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp, |
183 | char *fp, int count); | |
1da177e4 LT |
184 | static void n_hdlc_tty_wakeup(struct tty_struct *tty); |
185 | ||
1da177e4 LT |
186 | #define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data)) |
187 | #define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty) | |
188 | ||
be10eb75 PF |
189 | static void flush_rx_queue(struct tty_struct *tty) |
190 | { | |
191 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
192 | struct n_hdlc_buf *buf; | |
193 | ||
194 | while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list))) | |
195 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf); | |
196 | } | |
197 | ||
198 | static void flush_tx_queue(struct tty_struct *tty) | |
199 | { | |
200 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
201 | struct n_hdlc_buf *buf; | |
be10eb75 PF |
202 | |
203 | while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list))) | |
204 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf); | |
be10eb75 PF |
205 | } |
206 | ||
a352def2 | 207 | static struct tty_ldisc_ops n_hdlc_ldisc = { |
1da177e4 LT |
208 | .owner = THIS_MODULE, |
209 | .magic = TTY_LDISC_MAGIC, | |
210 | .name = "hdlc", | |
211 | .open = n_hdlc_tty_open, | |
212 | .close = n_hdlc_tty_close, | |
213 | .read = n_hdlc_tty_read, | |
214 | .write = n_hdlc_tty_write, | |
215 | .ioctl = n_hdlc_tty_ioctl, | |
216 | .poll = n_hdlc_tty_poll, | |
217 | .receive_buf = n_hdlc_tty_receive, | |
1da177e4 | 218 | .write_wakeup = n_hdlc_tty_wakeup, |
be10eb75 | 219 | .flush_buffer = flush_rx_queue, |
1da177e4 LT |
220 | }; |
221 | ||
222 | /** | |
223 | * n_hdlc_release - release an n_hdlc per device line discipline info structure | |
224 | * @n_hdlc - per device line discipline info structure | |
225 | */ | |
226 | static void n_hdlc_release(struct n_hdlc *n_hdlc) | |
227 | { | |
228 | struct tty_struct *tty = n_hdlc2tty (n_hdlc); | |
229 | struct n_hdlc_buf *buf; | |
66c3bdf1 | 230 | |
1da177e4 LT |
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 | ||
827afdf0 | 235 | if (tty->disc_data == n_hdlc) |
1da177e4 LT |
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 | } | |
1da177e4 LT |
267 | kfree(n_hdlc); |
268 | ||
269 | } /* end of n_hdlc_release() */ | |
270 | ||
271 | /** | |
272 | * n_hdlc_tty_close - line discipline close | |
273 | * @tty - pointer to tty info structure | |
274 | * | |
275 | * Called when the line discipline is changed to something | |
276 | * else, the tty is closed, or the tty detects a hangup. | |
277 | */ | |
278 | static void n_hdlc_tty_close(struct tty_struct *tty) | |
279 | { | |
280 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
281 | ||
1da177e4 LT |
282 | if (n_hdlc != NULL) { |
283 | if (n_hdlc->magic != HDLC_MAGIC) { | |
284 | printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n"); | |
285 | return; | |
286 | } | |
287 | #if defined(TTY_NO_WRITE_SPLIT) | |
288 | clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
289 | #endif | |
290 | tty->disc_data = NULL; | |
291 | if (tty == n_hdlc->backup_tty) | |
292 | n_hdlc->backup_tty = NULL; | |
293 | if (tty != n_hdlc->tty) | |
294 | return; | |
295 | if (n_hdlc->backup_tty) { | |
296 | n_hdlc->tty = n_hdlc->backup_tty; | |
297 | } else { | |
298 | n_hdlc_release (n_hdlc); | |
299 | } | |
300 | } | |
1da177e4 LT |
301 | } /* end of n_hdlc_tty_close() */ |
302 | ||
303 | /** | |
304 | * n_hdlc_tty_open - called when line discipline changed to n_hdlc | |
305 | * @tty - pointer to tty info structure | |
306 | * | |
307 | * Returns 0 if success, otherwise error code | |
308 | */ | |
309 | static int n_hdlc_tty_open (struct tty_struct *tty) | |
310 | { | |
311 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
312 | ||
313 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
314 | printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n", | |
315 | __FILE__,__LINE__, | |
316 | tty->name); | |
317 | ||
318 | /* There should not be an existing table for this slot. */ | |
319 | if (n_hdlc) { | |
320 | printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" ); | |
321 | return -EEXIST; | |
322 | } | |
323 | ||
324 | n_hdlc = n_hdlc_alloc(); | |
325 | if (!n_hdlc) { | |
326 | printk (KERN_ERR "n_hdlc_alloc failed\n"); | |
327 | return -ENFILE; | |
328 | } | |
329 | ||
330 | tty->disc_data = n_hdlc; | |
331 | n_hdlc->tty = tty; | |
33f0f88f | 332 | tty->receive_room = 65536; |
1da177e4 LT |
333 | |
334 | #if defined(TTY_NO_WRITE_SPLIT) | |
335 | /* change tty_io write() to not split large writes into 8K chunks */ | |
336 | set_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
337 | #endif | |
338 | ||
be10eb75 | 339 | /* flush receive data from driver */ |
f34d7a5b | 340 | tty_driver_flush_buffer(tty); |
66c3bdf1 | 341 | |
1da177e4 LT |
342 | return 0; |
343 | ||
344 | } /* end of n_tty_hdlc_open() */ | |
345 | ||
346 | /** | |
347 | * n_hdlc_send_frames - send frames on pending send buffer list | |
348 | * @n_hdlc - pointer to ldisc instance data | |
349 | * @tty - pointer to tty instance data | |
350 | * | |
351 | * Send frames on pending send buffer list until the driver does not accept a | |
352 | * frame (busy) this function is called after adding a frame to the send buffer | |
353 | * list and by the tty wakeup callback. | |
354 | */ | |
355 | static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) | |
356 | { | |
357 | register int actual; | |
358 | unsigned long flags; | |
359 | struct n_hdlc_buf *tbuf; | |
360 | ||
1da177e4 LT |
361 | check_again: |
362 | ||
363 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
364 | if (n_hdlc->tbusy) { | |
365 | n_hdlc->woke_up = 1; | |
366 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
367 | return; | |
368 | } | |
369 | n_hdlc->tbusy = 1; | |
370 | n_hdlc->woke_up = 0; | |
371 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
372 | ||
82f2341c | 373 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); |
1da177e4 LT |
374 | while (tbuf) { |
375 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
376 | printk("%s(%d)sending frame %p, count=%d\n", | |
377 | __FILE__,__LINE__,tbuf,tbuf->count); | |
378 | ||
379 | /* Send the next block of data to device */ | |
7962fce9 | 380 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
f34d7a5b | 381 | actual = tty->ops->write(tty, tbuf->buf, tbuf->count); |
b0fed314 JS |
382 | |
383 | /* rollback was possible and has been done */ | |
384 | if (actual == -ERESTARTSYS) { | |
82f2341c | 385 | n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); |
b0fed314 JS |
386 | break; |
387 | } | |
1da177e4 LT |
388 | /* if transmit error, throw frame away by */ |
389 | /* pretending it was accepted by driver */ | |
390 | if (actual < 0) | |
391 | actual = tbuf->count; | |
392 | ||
393 | if (actual == tbuf->count) { | |
394 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
395 | printk("%s(%d)frame %p completed\n", | |
396 | __FILE__,__LINE__,tbuf); | |
397 | ||
398 | /* free current transmit buffer */ | |
399 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf); | |
82f2341c | 400 | |
1da177e4 LT |
401 | /* wait up sleeping writers */ |
402 | wake_up_interruptible(&tty->write_wait); | |
403 | ||
404 | /* get next pending transmit buffer */ | |
405 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
406 | } else { | |
407 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
408 | printk("%s(%d)frame %p pending\n", | |
409 | __FILE__,__LINE__,tbuf); | |
82f2341c AP |
410 | |
411 | /* | |
412 | * the buffer was not accepted by driver, | |
413 | * return it back into tx queue | |
414 | */ | |
415 | n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); | |
1da177e4 LT |
416 | break; |
417 | } | |
418 | } | |
419 | ||
420 | if (!tbuf) | |
7962fce9 | 421 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
1da177e4 LT |
422 | |
423 | /* Clear the re-entry flag */ | |
424 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
425 | n_hdlc->tbusy = 0; | |
426 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
427 | ||
428 | if (n_hdlc->woke_up) | |
429 | goto check_again; | |
1da177e4 LT |
430 | } /* end of n_hdlc_send_frames() */ |
431 | ||
432 | /** | |
433 | * n_hdlc_tty_wakeup - Callback for transmit wakeup | |
434 | * @tty - pointer to associated tty instance data | |
435 | * | |
436 | * Called when low level device driver can accept more send data. | |
437 | */ | |
438 | static void n_hdlc_tty_wakeup(struct tty_struct *tty) | |
439 | { | |
440 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
441 | ||
1da177e4 LT |
442 | if (!n_hdlc) |
443 | return; | |
444 | ||
445 | if (tty != n_hdlc->tty) { | |
7962fce9 | 446 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
1da177e4 LT |
447 | return; |
448 | } | |
449 | ||
450 | n_hdlc_send_frames (n_hdlc, tty); | |
451 | ||
452 | } /* end of n_hdlc_tty_wakeup() */ | |
453 | ||
1da177e4 LT |
454 | /** |
455 | * n_hdlc_tty_receive - Called by tty driver when receive data is available | |
456 | * @tty - pointer to tty instance data | |
457 | * @data - pointer to received data | |
458 | * @flags - pointer to flags for data | |
459 | * @count - count of received data in bytes | |
460 | * | |
461 | * Called by tty low level driver when receive data is available. Data is | |
462 | * interpreted as one HDLC frame. | |
463 | */ | |
55db4c64 LT |
464 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data, |
465 | char *flags, int count) | |
1da177e4 LT |
466 | { |
467 | register struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
468 | register struct n_hdlc_buf *buf; | |
469 | ||
470 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
471 | printk("%s(%d)n_hdlc_tty_receive() called count=%d\n", | |
472 | __FILE__,__LINE__, count); | |
473 | ||
474 | /* This can happen if stuff comes in on the backup tty */ | |
a01e035e | 475 | if (!n_hdlc || tty != n_hdlc->tty) |
55db4c64 | 476 | return; |
1da177e4 LT |
477 | |
478 | /* verify line is using HDLC discipline */ | |
479 | if (n_hdlc->magic != HDLC_MAGIC) { | |
480 | printk("%s(%d) line not using HDLC discipline\n", | |
481 | __FILE__,__LINE__); | |
55db4c64 | 482 | return; |
1da177e4 LT |
483 | } |
484 | ||
485 | if ( count>maxframe ) { | |
486 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
487 | printk("%s(%d) rx count>maxframesize, data discarded\n", | |
488 | __FILE__,__LINE__); | |
55db4c64 | 489 | return; |
1da177e4 LT |
490 | } |
491 | ||
492 | /* get a free HDLC buffer */ | |
493 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
494 | if (!buf) { | |
495 | /* no buffers in free list, attempt to allocate another rx buffer */ | |
496 | /* unless the maximum count has been reached */ | |
497 | if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT) | |
85f4c951 GS |
498 | buf = kmalloc(struct_size(buf, buf, maxframe), |
499 | GFP_ATOMIC); | |
1da177e4 LT |
500 | } |
501 | ||
502 | if (!buf) { | |
503 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
504 | printk("%s(%d) no more rx buffers, data discarded\n", | |
505 | __FILE__,__LINE__); | |
55db4c64 | 506 | return; |
1da177e4 LT |
507 | } |
508 | ||
509 | /* copy received data to HDLC buffer */ | |
510 | memcpy(buf->buf,data,count); | |
511 | buf->count=count; | |
512 | ||
513 | /* add HDLC buffer to list of received frames */ | |
514 | n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf); | |
515 | ||
516 | /* wake up any blocked reads and perform async signalling */ | |
517 | wake_up_interruptible (&tty->read_wait); | |
518 | if (n_hdlc->tty->fasync != NULL) | |
519 | kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN); | |
520 | ||
521 | } /* end of n_hdlc_tty_receive() */ | |
522 | ||
523 | /** | |
4a4efbde | 524 | * n_hdlc_tty_read - Called to retrieve one frame of data (if available) |
1da177e4 LT |
525 | * @tty - pointer to tty instance data |
526 | * @file - pointer to open file object | |
527 | * @buf - pointer to returned data buffer | |
528 | * @nr - size of returned data buffer | |
529 | * | |
530 | * Returns the number of bytes returned or error code. | |
531 | */ | |
532 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
533 | __u8 __user *buf, size_t nr) | |
534 | { | |
535 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
1035b63d | 536 | int ret = 0; |
1da177e4 | 537 | struct n_hdlc_buf *rbuf; |
1035b63d | 538 | DECLARE_WAITQUEUE(wait, current); |
1da177e4 | 539 | |
1da177e4 LT |
540 | /* Validate the pointers */ |
541 | if (!n_hdlc) | |
542 | return -EIO; | |
543 | ||
544 | /* verify user access to buffer */ | |
96d4f267 | 545 | if (!access_ok(buf, nr)) { |
1da177e4 LT |
546 | printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user " |
547 | "buffer\n", __FILE__, __LINE__); | |
548 | return -EFAULT; | |
549 | } | |
550 | ||
1035b63d | 551 | add_wait_queue(&tty->read_wait, &wait); |
04f378b1 | 552 | |
1da177e4 | 553 | for (;;) { |
0f40fbbc | 554 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { |
1035b63d PF |
555 | ret = -EIO; |
556 | break; | |
04f378b1 | 557 | } |
1035b63d PF |
558 | if (tty_hung_up_p(file)) |
559 | break; | |
1da177e4 | 560 | |
1035b63d | 561 | set_current_state(TASK_INTERRUPTIBLE); |
1da177e4 LT |
562 | |
563 | rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
1035b63d PF |
564 | if (rbuf) { |
565 | if (rbuf->count > nr) { | |
566 | /* too large for caller's buffer */ | |
567 | ret = -EOVERFLOW; | |
568 | } else { | |
fc01d8c6 | 569 | __set_current_state(TASK_RUNNING); |
1035b63d PF |
570 | if (copy_to_user(buf, rbuf->buf, rbuf->count)) |
571 | ret = -EFAULT; | |
572 | else | |
573 | ret = rbuf->count; | |
574 | } | |
575 | ||
576 | if (n_hdlc->rx_free_buf_list.count > | |
577 | DEFAULT_RX_BUF_COUNT) | |
578 | kfree(rbuf); | |
579 | else | |
580 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf); | |
1da177e4 | 581 | break; |
1035b63d | 582 | } |
1da177e4 LT |
583 | |
584 | /* no data */ | |
c96cf923 | 585 | if (tty_io_nonblock(tty, file)) { |
1035b63d PF |
586 | ret = -EAGAIN; |
587 | break; | |
04f378b1 | 588 | } |
1035b63d PF |
589 | |
590 | schedule(); | |
591 | ||
04f378b1 | 592 | if (signal_pending(current)) { |
1035b63d PF |
593 | ret = -EINTR; |
594 | break; | |
04f378b1 | 595 | } |
1da177e4 | 596 | } |
1035b63d PF |
597 | |
598 | remove_wait_queue(&tty->read_wait, &wait); | |
599 | __set_current_state(TASK_RUNNING); | |
600 | ||
1da177e4 LT |
601 | return ret; |
602 | ||
603 | } /* end of n_hdlc_tty_read() */ | |
604 | ||
605 | /** | |
606 | * n_hdlc_tty_write - write a single frame of data to device | |
607 | * @tty - pointer to associated tty device instance data | |
608 | * @file - pointer to file object data | |
609 | * @data - pointer to transmit data (one frame) | |
610 | * @count - size of transmit frame in bytes | |
611 | * | |
612 | * Returns the number of bytes written (or error code). | |
613 | */ | |
614 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
615 | const unsigned char *data, size_t count) | |
616 | { | |
617 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
618 | int error = 0; | |
619 | DECLARE_WAITQUEUE(wait, current); | |
620 | struct n_hdlc_buf *tbuf; | |
621 | ||
622 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
5b5e0928 | 623 | printk("%s(%d)n_hdlc_tty_write() called count=%zd\n", |
1da177e4 LT |
624 | __FILE__,__LINE__,count); |
625 | ||
626 | /* Verify pointers */ | |
627 | if (!n_hdlc) | |
628 | return -EIO; | |
629 | ||
630 | if (n_hdlc->magic != HDLC_MAGIC) | |
631 | return -EIO; | |
632 | ||
633 | /* verify frame size */ | |
634 | if (count > maxframe ) { | |
635 | if (debuglevel & DEBUG_LEVEL_INFO) | |
636 | printk (KERN_WARNING | |
637 | "n_hdlc_tty_write: truncating user packet " | |
638 | "from %lu to %d\n", (unsigned long) count, | |
639 | maxframe ); | |
640 | count = maxframe; | |
641 | } | |
642 | ||
643 | add_wait_queue(&tty->write_wait, &wait); | |
1035b63d PF |
644 | |
645 | for (;;) { | |
646 | set_current_state(TASK_INTERRUPTIBLE); | |
1da177e4 | 647 | |
1035b63d PF |
648 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); |
649 | if (tbuf) | |
650 | break; | |
651 | ||
c96cf923 | 652 | if (tty_io_nonblock(tty, file)) { |
c72f527c PF |
653 | error = -EAGAIN; |
654 | break; | |
655 | } | |
1da177e4 LT |
656 | schedule(); |
657 | ||
658 | n_hdlc = tty2n_hdlc (tty); | |
659 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || | |
660 | tty != n_hdlc->tty) { | |
661 | printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc); | |
662 | error = -EIO; | |
663 | break; | |
664 | } | |
665 | ||
666 | if (signal_pending(current)) { | |
667 | error = -EINTR; | |
668 | break; | |
669 | } | |
670 | } | |
671 | ||
1035b63d | 672 | __set_current_state(TASK_RUNNING); |
1da177e4 LT |
673 | remove_wait_queue(&tty->write_wait, &wait); |
674 | ||
675 | if (!error) { | |
676 | /* Retrieve the user's buffer */ | |
677 | memcpy(tbuf->buf, data, count); | |
678 | ||
679 | /* Send the data */ | |
680 | tbuf->count = error = count; | |
681 | n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf); | |
682 | n_hdlc_send_frames(n_hdlc,tty); | |
683 | } | |
1035b63d | 684 | |
1da177e4 LT |
685 | return error; |
686 | ||
687 | } /* end of n_hdlc_tty_write() */ | |
688 | ||
689 | /** | |
690 | * n_hdlc_tty_ioctl - process IOCTL system call for the tty device. | |
691 | * @tty - pointer to tty instance data | |
692 | * @file - pointer to open file object for device | |
693 | * @cmd - IOCTL command code | |
694 | * @arg - argument for IOCTL call (cmd dependent) | |
695 | * | |
696 | * Returns command dependent result. | |
697 | */ | |
698 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
699 | unsigned int cmd, unsigned long arg) | |
700 | { | |
701 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
702 | int error = 0; | |
703 | int count; | |
704 | unsigned long flags; | |
82f2341c AP |
705 | struct n_hdlc_buf *buf = NULL; |
706 | ||
1da177e4 LT |
707 | if (debuglevel >= DEBUG_LEVEL_INFO) |
708 | printk("%s(%d)n_hdlc_tty_ioctl() called %d\n", | |
709 | __FILE__,__LINE__,cmd); | |
710 | ||
711 | /* Verify the status of the device */ | |
712 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC) | |
713 | return -EBADF; | |
714 | ||
715 | switch (cmd) { | |
716 | case FIONREAD: | |
717 | /* report count of read data available */ | |
718 | /* in next available frame (if any) */ | |
719 | spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags); | |
82f2341c AP |
720 | buf = list_first_entry_or_null(&n_hdlc->rx_buf_list.list, |
721 | struct n_hdlc_buf, list_item); | |
722 | if (buf) | |
723 | count = buf->count; | |
1da177e4 LT |
724 | else |
725 | count = 0; | |
726 | spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags); | |
727 | error = put_user(count, (int __user *)arg); | |
728 | break; | |
729 | ||
730 | case TIOCOUTQ: | |
731 | /* get the pending tx byte count in the driver */ | |
f34d7a5b | 732 | count = tty_chars_in_buffer(tty); |
1da177e4 LT |
733 | /* add size of next output frame in queue */ |
734 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags); | |
82f2341c AP |
735 | buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list, |
736 | struct n_hdlc_buf, list_item); | |
737 | if (buf) | |
738 | count += buf->count; | |
1da177e4 LT |
739 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags); |
740 | error = put_user(count, (int __user *)arg); | |
741 | break; | |
742 | ||
be10eb75 PF |
743 | case TCFLSH: |
744 | switch (arg) { | |
745 | case TCIOFLUSH: | |
746 | case TCOFLUSH: | |
747 | flush_tx_queue(tty); | |
748 | } | |
361bf8a9 | 749 | /* fall through - to default */ |
be10eb75 | 750 | |
1da177e4 | 751 | default: |
47afa7a5 | 752 | error = n_tty_ioctl_helper(tty, file, cmd, arg); |
1da177e4 LT |
753 | break; |
754 | } | |
755 | return error; | |
756 | ||
757 | } /* end of n_hdlc_tty_ioctl() */ | |
758 | ||
759 | /** | |
760 | * n_hdlc_tty_poll - TTY callback for poll system call | |
761 | * @tty - pointer to tty instance data | |
762 | * @filp - pointer to open file object for device | |
763 | * @poll_table - wait queue for operations | |
764 | * | |
765 | * Determine which operations (read/write) will not block and return info | |
766 | * to caller. | |
767 | * Returns a bit mask containing info on which ops will not block. | |
768 | */ | |
afc9a42b | 769 | static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, |
1da177e4 LT |
770 | poll_table *wait) |
771 | { | |
772 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
afc9a42b | 773 | __poll_t mask = 0; |
1da177e4 | 774 | |
1da177e4 LT |
775 | if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) { |
776 | /* queue current process into any wait queue that */ | |
777 | /* may awaken in the future (read and write) */ | |
778 | ||
779 | poll_wait(filp, &tty->read_wait, wait); | |
780 | poll_wait(filp, &tty->write_wait, wait); | |
781 | ||
782 | /* set bits for operations that won't block */ | |
82f2341c | 783 | if (!list_empty(&n_hdlc->rx_buf_list.list)) |
a9a08845 | 784 | mask |= EPOLLIN | EPOLLRDNORM; /* readable */ |
0f40fbbc | 785 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) |
a9a08845 | 786 | mask |= EPOLLHUP; |
9c1729db | 787 | if (tty_hung_up_p(filp)) |
a9a08845 | 788 | mask |= EPOLLHUP; |
9c1729db | 789 | if (!tty_is_writelocked(tty) && |
82f2341c | 790 | !list_empty(&n_hdlc->tx_free_buf_list.list)) |
a9a08845 | 791 | mask |= EPOLLOUT | EPOLLWRNORM; /* writable */ |
1da177e4 LT |
792 | } |
793 | return mask; | |
794 | } /* end of n_hdlc_tty_poll() */ | |
795 | ||
796 | /** | |
797 | * n_hdlc_alloc - allocate an n_hdlc instance data structure | |
798 | * | |
799 | * Returns a pointer to newly created structure if success, otherwise %NULL | |
800 | */ | |
801 | static struct n_hdlc *n_hdlc_alloc(void) | |
802 | { | |
803 | struct n_hdlc_buf *buf; | |
804 | int i; | |
8e25f8ce | 805 | struct n_hdlc *n_hdlc = kzalloc(sizeof(*n_hdlc), GFP_KERNEL); |
1da177e4 LT |
806 | |
807 | if (!n_hdlc) | |
808 | return NULL; | |
809 | ||
e9b736d8 JS |
810 | spin_lock_init(&n_hdlc->rx_free_buf_list.spinlock); |
811 | spin_lock_init(&n_hdlc->tx_free_buf_list.spinlock); | |
812 | spin_lock_init(&n_hdlc->rx_buf_list.spinlock); | |
813 | spin_lock_init(&n_hdlc->tx_buf_list.spinlock); | |
82f2341c AP |
814 | |
815 | INIT_LIST_HEAD(&n_hdlc->rx_free_buf_list.list); | |
816 | INIT_LIST_HEAD(&n_hdlc->tx_free_buf_list.list); | |
817 | INIT_LIST_HEAD(&n_hdlc->rx_buf_list.list); | |
818 | INIT_LIST_HEAD(&n_hdlc->tx_buf_list.list); | |
819 | ||
1da177e4 LT |
820 | /* allocate free rx buffer list */ |
821 | for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) { | |
85f4c951 | 822 | buf = kmalloc(struct_size(buf, buf, maxframe), GFP_KERNEL); |
1da177e4 LT |
823 | if (buf) |
824 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf); | |
825 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
826 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i); | |
827 | } | |
828 | ||
829 | /* allocate free tx buffer list */ | |
830 | for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) { | |
85f4c951 | 831 | buf = kmalloc(struct_size(buf, buf, maxframe), GFP_KERNEL); |
1da177e4 LT |
832 | if (buf) |
833 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf); | |
834 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
835 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i); | |
836 | } | |
837 | ||
838 | /* Initialize the control block */ | |
839 | n_hdlc->magic = HDLC_MAGIC; | |
840 | n_hdlc->flags = 0; | |
841 | ||
842 | return n_hdlc; | |
843 | ||
844 | } /* end of n_hdlc_alloc() */ | |
845 | ||
82f2341c AP |
846 | /** |
847 | * n_hdlc_buf_return - put the HDLC buffer after the head of the specified list | |
848 | * @buf_list - pointer to the buffer list | |
849 | * @buf - pointer to the buffer | |
850 | */ | |
851 | static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, | |
852 | struct n_hdlc_buf *buf) | |
853 | { | |
854 | unsigned long flags; | |
855 | ||
856 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
857 | ||
858 | list_add(&buf->list_item, &buf_list->list); | |
859 | buf_list->count++; | |
860 | ||
861 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
862 | } | |
863 | ||
1da177e4 LT |
864 | /** |
865 | * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list | |
82f2341c | 866 | * @buf_list - pointer to buffer list |
1da177e4 LT |
867 | * @buf - pointer to buffer |
868 | */ | |
82f2341c | 869 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list, |
1da177e4 LT |
870 | struct n_hdlc_buf *buf) |
871 | { | |
872 | unsigned long flags; | |
82f2341c AP |
873 | |
874 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
875 | ||
876 | list_add_tail(&buf->list_item, &buf_list->list); | |
877 | buf_list->count++; | |
878 | ||
879 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
1da177e4 LT |
880 | } /* end of n_hdlc_buf_put() */ |
881 | ||
882 | /** | |
883 | * n_hdlc_buf_get - remove and return an HDLC buffer from list | |
82f2341c | 884 | * @buf_list - pointer to HDLC buffer list |
1da177e4 LT |
885 | * |
886 | * Remove and return an HDLC buffer from the head of the specified HDLC buffer | |
887 | * list. | |
888 | * Returns a pointer to HDLC buffer if available, otherwise %NULL. | |
889 | */ | |
82f2341c | 890 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list) |
1da177e4 LT |
891 | { |
892 | unsigned long flags; | |
893 | struct n_hdlc_buf *buf; | |
82f2341c AP |
894 | |
895 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
896 | ||
897 | buf = list_first_entry_or_null(&buf_list->list, | |
898 | struct n_hdlc_buf, list_item); | |
1da177e4 | 899 | if (buf) { |
82f2341c AP |
900 | list_del(&buf->list_item); |
901 | buf_list->count--; | |
1da177e4 | 902 | } |
82f2341c AP |
903 | |
904 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
1da177e4 | 905 | return buf; |
1da177e4 LT |
906 | } /* end of n_hdlc_buf_get() */ |
907 | ||
06324664 | 908 | static const char hdlc_banner[] __initconst = |
be10eb75 | 909 | KERN_INFO "HDLC line discipline maxframe=%u\n"; |
06324664 | 910 | static const char hdlc_register_ok[] __initconst = |
1da177e4 | 911 | KERN_INFO "N_HDLC line discipline registered.\n"; |
06324664 | 912 | static const char hdlc_register_fail[] __initconst = |
1da177e4 | 913 | KERN_ERR "error registering line discipline: %d\n"; |
1da177e4 LT |
914 | |
915 | static int __init n_hdlc_init(void) | |
916 | { | |
917 | int status; | |
918 | ||
919 | /* range check maxframe arg */ | |
920 | if (maxframe < 4096) | |
921 | maxframe = 4096; | |
922 | else if (maxframe > 65535) | |
923 | maxframe = 65535; | |
924 | ||
925 | printk(hdlc_banner, maxframe); | |
926 | ||
927 | status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc); | |
928 | if (!status) | |
929 | printk(hdlc_register_ok); | |
930 | else | |
931 | printk(hdlc_register_fail, status); | |
932 | ||
1da177e4 LT |
933 | return status; |
934 | ||
935 | } /* end of init_module() */ | |
936 | ||
47a7e5e9 RD |
937 | #ifdef CONFIG_SPARC |
938 | #undef __exitdata | |
939 | #define __exitdata | |
940 | #endif | |
941 | ||
06324664 | 942 | static const char hdlc_unregister_ok[] __exitdata = |
1da177e4 | 943 | KERN_INFO "N_HDLC: line discipline unregistered\n"; |
06324664 | 944 | static const char hdlc_unregister_fail[] __exitdata = |
1da177e4 LT |
945 | KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n"; |
946 | ||
947 | static void __exit n_hdlc_exit(void) | |
948 | { | |
949 | /* Release tty registration of line discipline */ | |
64ccd715 | 950 | int status = tty_unregister_ldisc(N_HDLC); |
1da177e4 LT |
951 | |
952 | if (status) | |
953 | printk(hdlc_unregister_fail, status); | |
954 | else | |
955 | printk(hdlc_unregister_ok); | |
956 | } | |
957 | ||
958 | module_init(n_hdlc_init); | |
959 | module_exit(n_hdlc_exit); | |
960 | ||
961 | MODULE_LICENSE("GPL"); | |
962 | MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com"); | |
963 | module_param(debuglevel, int, 0); | |
964 | module_param(maxframe, int, 0); | |
965 | MODULE_ALIAS_LDISC(N_HDLC); |