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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 | ||
1da177e4 LT |
163 | /* max frame size for memory allocations */ |
164 | static int maxframe = 4096; | |
165 | ||
166 | /* TTY callbacks */ | |
167 | ||
168 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
169 | __u8 __user *buf, size_t nr); | |
170 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
171 | const unsigned char *buf, size_t nr); | |
172 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
173 | unsigned int cmd, unsigned long arg); | |
afc9a42b | 174 | static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, |
1da177e4 LT |
175 | poll_table *wait); |
176 | static int n_hdlc_tty_open(struct tty_struct *tty); | |
177 | static void n_hdlc_tty_close(struct tty_struct *tty); | |
55db4c64 LT |
178 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp, |
179 | char *fp, int count); | |
1da177e4 LT |
180 | static void n_hdlc_tty_wakeup(struct tty_struct *tty); |
181 | ||
1da177e4 LT |
182 | #define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data)) |
183 | #define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty) | |
184 | ||
be10eb75 PF |
185 | static void flush_rx_queue(struct tty_struct *tty) |
186 | { | |
187 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
188 | struct n_hdlc_buf *buf; | |
189 | ||
190 | while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list))) | |
191 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf); | |
192 | } | |
193 | ||
194 | static void flush_tx_queue(struct tty_struct *tty) | |
195 | { | |
196 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
197 | struct n_hdlc_buf *buf; | |
be10eb75 PF |
198 | |
199 | while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list))) | |
200 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf); | |
be10eb75 PF |
201 | } |
202 | ||
a352def2 | 203 | static struct tty_ldisc_ops n_hdlc_ldisc = { |
1da177e4 LT |
204 | .owner = THIS_MODULE, |
205 | .magic = TTY_LDISC_MAGIC, | |
206 | .name = "hdlc", | |
207 | .open = n_hdlc_tty_open, | |
208 | .close = n_hdlc_tty_close, | |
209 | .read = n_hdlc_tty_read, | |
210 | .write = n_hdlc_tty_write, | |
211 | .ioctl = n_hdlc_tty_ioctl, | |
212 | .poll = n_hdlc_tty_poll, | |
213 | .receive_buf = n_hdlc_tty_receive, | |
1da177e4 | 214 | .write_wakeup = n_hdlc_tty_wakeup, |
be10eb75 | 215 | .flush_buffer = flush_rx_queue, |
1da177e4 LT |
216 | }; |
217 | ||
30fafd92 JS |
218 | static void n_hdlc_free_buf_list(struct n_hdlc_buf_list *list) |
219 | { | |
220 | struct n_hdlc_buf *buf; | |
221 | ||
222 | do { | |
223 | buf = n_hdlc_buf_get(list); | |
224 | kfree(buf); | |
225 | } while (buf); | |
226 | } | |
227 | ||
1da177e4 LT |
228 | /** |
229 | * n_hdlc_release - release an n_hdlc per device line discipline info structure | |
230 | * @n_hdlc - per device line discipline info structure | |
231 | */ | |
232 | static void n_hdlc_release(struct n_hdlc *n_hdlc) | |
233 | { | |
234 | struct tty_struct *tty = n_hdlc2tty (n_hdlc); | |
66c3bdf1 | 235 | |
1da177e4 LT |
236 | /* Ensure that the n_hdlcd process is not hanging on select()/poll() */ |
237 | wake_up_interruptible (&tty->read_wait); | |
238 | wake_up_interruptible (&tty->write_wait); | |
239 | ||
827afdf0 | 240 | if (tty->disc_data == n_hdlc) |
1da177e4 LT |
241 | tty->disc_data = NULL; /* Break the tty->n_hdlc link */ |
242 | ||
30fafd92 JS |
243 | n_hdlc_free_buf_list(&n_hdlc->rx_free_buf_list); |
244 | n_hdlc_free_buf_list(&n_hdlc->tx_free_buf_list); | |
245 | n_hdlc_free_buf_list(&n_hdlc->rx_buf_list); | |
246 | n_hdlc_free_buf_list(&n_hdlc->tx_buf_list); | |
1da177e4 | 247 | kfree(n_hdlc); |
1da177e4 LT |
248 | } /* end of n_hdlc_release() */ |
249 | ||
250 | /** | |
251 | * n_hdlc_tty_close - line discipline close | |
252 | * @tty - pointer to tty info structure | |
253 | * | |
254 | * Called when the line discipline is changed to something | |
255 | * else, the tty is closed, or the tty detects a hangup. | |
256 | */ | |
257 | static void n_hdlc_tty_close(struct tty_struct *tty) | |
258 | { | |
259 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
260 | ||
5f289514 JS |
261 | if (!n_hdlc) |
262 | return; | |
263 | ||
264 | if (n_hdlc->magic != HDLC_MAGIC) { | |
265 | printk(KERN_WARNING "n_hdlc: trying to close unopened tty!\n"); | |
266 | return; | |
267 | } | |
1da177e4 | 268 | #if defined(TTY_NO_WRITE_SPLIT) |
5f289514 | 269 | clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags); |
1da177e4 | 270 | #endif |
5f289514 JS |
271 | tty->disc_data = NULL; |
272 | if (tty == n_hdlc->backup_tty) | |
273 | n_hdlc->backup_tty = NULL; | |
274 | if (tty != n_hdlc->tty) | |
275 | return; | |
276 | if (n_hdlc->backup_tty) { | |
277 | n_hdlc->tty = n_hdlc->backup_tty; | |
278 | } else { | |
279 | n_hdlc_release (n_hdlc); | |
1da177e4 | 280 | } |
1da177e4 LT |
281 | } /* end of n_hdlc_tty_close() */ |
282 | ||
283 | /** | |
284 | * n_hdlc_tty_open - called when line discipline changed to n_hdlc | |
285 | * @tty - pointer to tty info structure | |
286 | * | |
287 | * Returns 0 if success, otherwise error code | |
288 | */ | |
289 | static int n_hdlc_tty_open (struct tty_struct *tty) | |
290 | { | |
291 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
292 | ||
f3c2e277 JS |
293 | pr_debug("%s(%d)%s() called (device=%s)\n", |
294 | __FILE__, __LINE__, __func__, tty->name); | |
295 | ||
1da177e4 LT |
296 | /* There should not be an existing table for this slot. */ |
297 | if (n_hdlc) { | |
298 | printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" ); | |
299 | return -EEXIST; | |
300 | } | |
301 | ||
302 | n_hdlc = n_hdlc_alloc(); | |
303 | if (!n_hdlc) { | |
304 | printk (KERN_ERR "n_hdlc_alloc failed\n"); | |
305 | return -ENFILE; | |
306 | } | |
307 | ||
308 | tty->disc_data = n_hdlc; | |
309 | n_hdlc->tty = tty; | |
33f0f88f | 310 | tty->receive_room = 65536; |
1da177e4 LT |
311 | |
312 | #if defined(TTY_NO_WRITE_SPLIT) | |
313 | /* change tty_io write() to not split large writes into 8K chunks */ | |
314 | set_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
315 | #endif | |
316 | ||
be10eb75 | 317 | /* flush receive data from driver */ |
f34d7a5b | 318 | tty_driver_flush_buffer(tty); |
66c3bdf1 | 319 | |
1da177e4 LT |
320 | return 0; |
321 | ||
322 | } /* end of n_tty_hdlc_open() */ | |
323 | ||
324 | /** | |
325 | * n_hdlc_send_frames - send frames on pending send buffer list | |
326 | * @n_hdlc - pointer to ldisc instance data | |
327 | * @tty - pointer to tty instance data | |
328 | * | |
329 | * Send frames on pending send buffer list until the driver does not accept a | |
330 | * frame (busy) this function is called after adding a frame to the send buffer | |
331 | * list and by the tty wakeup callback. | |
332 | */ | |
333 | static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) | |
334 | { | |
335 | register int actual; | |
336 | unsigned long flags; | |
337 | struct n_hdlc_buf *tbuf; | |
338 | ||
1da177e4 LT |
339 | check_again: |
340 | ||
341 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
342 | if (n_hdlc->tbusy) { | |
343 | n_hdlc->woke_up = 1; | |
344 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
345 | return; | |
346 | } | |
347 | n_hdlc->tbusy = 1; | |
348 | n_hdlc->woke_up = 0; | |
349 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
350 | ||
82f2341c | 351 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); |
1da177e4 | 352 | while (tbuf) { |
f3c2e277 JS |
353 | pr_debug("%s(%d)sending frame %p, count=%d\n", |
354 | __FILE__, __LINE__, tbuf, tbuf->count); | |
355 | ||
1da177e4 | 356 | /* Send the next block of data to device */ |
7962fce9 | 357 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
f34d7a5b | 358 | actual = tty->ops->write(tty, tbuf->buf, tbuf->count); |
b0fed314 JS |
359 | |
360 | /* rollback was possible and has been done */ | |
361 | if (actual == -ERESTARTSYS) { | |
82f2341c | 362 | n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); |
b0fed314 JS |
363 | break; |
364 | } | |
1da177e4 LT |
365 | /* if transmit error, throw frame away by */ |
366 | /* pretending it was accepted by driver */ | |
367 | if (actual < 0) | |
368 | actual = tbuf->count; | |
369 | ||
370 | if (actual == tbuf->count) { | |
f3c2e277 JS |
371 | pr_debug("%s(%d)frame %p completed\n", |
372 | __FILE__, __LINE__, tbuf); | |
373 | ||
1da177e4 LT |
374 | /* free current transmit buffer */ |
375 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf); | |
82f2341c | 376 | |
1da177e4 LT |
377 | /* wait up sleeping writers */ |
378 | wake_up_interruptible(&tty->write_wait); | |
379 | ||
380 | /* get next pending transmit buffer */ | |
381 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
382 | } else { | |
f3c2e277 JS |
383 | pr_debug("%s(%d)frame %p pending\n", |
384 | __FILE__, __LINE__, tbuf); | |
82f2341c AP |
385 | |
386 | /* | |
387 | * the buffer was not accepted by driver, | |
388 | * return it back into tx queue | |
389 | */ | |
390 | n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); | |
1da177e4 LT |
391 | break; |
392 | } | |
393 | } | |
394 | ||
395 | if (!tbuf) | |
7962fce9 | 396 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
1da177e4 LT |
397 | |
398 | /* Clear the re-entry flag */ | |
399 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
400 | n_hdlc->tbusy = 0; | |
401 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
402 | ||
403 | if (n_hdlc->woke_up) | |
404 | goto check_again; | |
1da177e4 LT |
405 | } /* end of n_hdlc_send_frames() */ |
406 | ||
407 | /** | |
408 | * n_hdlc_tty_wakeup - Callback for transmit wakeup | |
409 | * @tty - pointer to associated tty instance data | |
410 | * | |
411 | * Called when low level device driver can accept more send data. | |
412 | */ | |
413 | static void n_hdlc_tty_wakeup(struct tty_struct *tty) | |
414 | { | |
415 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
416 | ||
1da177e4 LT |
417 | if (!n_hdlc) |
418 | return; | |
419 | ||
420 | if (tty != n_hdlc->tty) { | |
7962fce9 | 421 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
1da177e4 LT |
422 | return; |
423 | } | |
424 | ||
425 | n_hdlc_send_frames (n_hdlc, tty); | |
426 | ||
427 | } /* end of n_hdlc_tty_wakeup() */ | |
428 | ||
1da177e4 LT |
429 | /** |
430 | * n_hdlc_tty_receive - Called by tty driver when receive data is available | |
431 | * @tty - pointer to tty instance data | |
432 | * @data - pointer to received data | |
433 | * @flags - pointer to flags for data | |
434 | * @count - count of received data in bytes | |
435 | * | |
436 | * Called by tty low level driver when receive data is available. Data is | |
437 | * interpreted as one HDLC frame. | |
438 | */ | |
55db4c64 LT |
439 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data, |
440 | char *flags, int count) | |
1da177e4 LT |
441 | { |
442 | register struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
443 | register struct n_hdlc_buf *buf; | |
444 | ||
f3c2e277 JS |
445 | pr_debug("%s(%d)%s() called count=%d\n", |
446 | __FILE__, __LINE__, __func__, count); | |
447 | ||
1da177e4 | 448 | /* This can happen if stuff comes in on the backup tty */ |
a01e035e | 449 | if (!n_hdlc || tty != n_hdlc->tty) |
55db4c64 | 450 | return; |
1da177e4 LT |
451 | |
452 | /* verify line is using HDLC discipline */ | |
453 | if (n_hdlc->magic != HDLC_MAGIC) { | |
454 | printk("%s(%d) line not using HDLC discipline\n", | |
455 | __FILE__,__LINE__); | |
55db4c64 | 456 | return; |
1da177e4 LT |
457 | } |
458 | ||
459 | if ( count>maxframe ) { | |
f3c2e277 JS |
460 | pr_debug("%s(%d) rx count>maxframesize, data discarded\n", |
461 | __FILE__, __LINE__); | |
55db4c64 | 462 | return; |
1da177e4 LT |
463 | } |
464 | ||
465 | /* get a free HDLC buffer */ | |
466 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
467 | if (!buf) { | |
468 | /* no buffers in free list, attempt to allocate another rx buffer */ | |
469 | /* unless the maximum count has been reached */ | |
470 | if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT) | |
85f4c951 GS |
471 | buf = kmalloc(struct_size(buf, buf, maxframe), |
472 | GFP_ATOMIC); | |
1da177e4 LT |
473 | } |
474 | ||
475 | if (!buf) { | |
f3c2e277 JS |
476 | pr_debug("%s(%d) no more rx buffers, data discarded\n", |
477 | __FILE__, __LINE__); | |
55db4c64 | 478 | return; |
1da177e4 LT |
479 | } |
480 | ||
481 | /* copy received data to HDLC buffer */ | |
482 | memcpy(buf->buf,data,count); | |
483 | buf->count=count; | |
484 | ||
485 | /* add HDLC buffer to list of received frames */ | |
486 | n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf); | |
487 | ||
488 | /* wake up any blocked reads and perform async signalling */ | |
489 | wake_up_interruptible (&tty->read_wait); | |
490 | if (n_hdlc->tty->fasync != NULL) | |
491 | kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN); | |
492 | ||
493 | } /* end of n_hdlc_tty_receive() */ | |
494 | ||
495 | /** | |
4a4efbde | 496 | * n_hdlc_tty_read - Called to retrieve one frame of data (if available) |
1da177e4 LT |
497 | * @tty - pointer to tty instance data |
498 | * @file - pointer to open file object | |
499 | * @buf - pointer to returned data buffer | |
500 | * @nr - size of returned data buffer | |
501 | * | |
502 | * Returns the number of bytes returned or error code. | |
503 | */ | |
504 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
505 | __u8 __user *buf, size_t nr) | |
506 | { | |
507 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
1035b63d | 508 | int ret = 0; |
1da177e4 | 509 | struct n_hdlc_buf *rbuf; |
1035b63d | 510 | DECLARE_WAITQUEUE(wait, current); |
1da177e4 | 511 | |
1da177e4 LT |
512 | /* Validate the pointers */ |
513 | if (!n_hdlc) | |
514 | return -EIO; | |
515 | ||
516 | /* verify user access to buffer */ | |
96d4f267 | 517 | if (!access_ok(buf, nr)) { |
1da177e4 LT |
518 | printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user " |
519 | "buffer\n", __FILE__, __LINE__); | |
520 | return -EFAULT; | |
521 | } | |
522 | ||
1035b63d | 523 | add_wait_queue(&tty->read_wait, &wait); |
04f378b1 | 524 | |
1da177e4 | 525 | for (;;) { |
0f40fbbc | 526 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { |
1035b63d PF |
527 | ret = -EIO; |
528 | break; | |
04f378b1 | 529 | } |
1035b63d PF |
530 | if (tty_hung_up_p(file)) |
531 | break; | |
1da177e4 | 532 | |
1035b63d | 533 | set_current_state(TASK_INTERRUPTIBLE); |
1da177e4 LT |
534 | |
535 | rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
1035b63d PF |
536 | if (rbuf) { |
537 | if (rbuf->count > nr) { | |
538 | /* too large for caller's buffer */ | |
539 | ret = -EOVERFLOW; | |
540 | } else { | |
fc01d8c6 | 541 | __set_current_state(TASK_RUNNING); |
1035b63d PF |
542 | if (copy_to_user(buf, rbuf->buf, rbuf->count)) |
543 | ret = -EFAULT; | |
544 | else | |
545 | ret = rbuf->count; | |
546 | } | |
547 | ||
548 | if (n_hdlc->rx_free_buf_list.count > | |
549 | DEFAULT_RX_BUF_COUNT) | |
550 | kfree(rbuf); | |
551 | else | |
552 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf); | |
1da177e4 | 553 | break; |
1035b63d | 554 | } |
1da177e4 LT |
555 | |
556 | /* no data */ | |
c96cf923 | 557 | if (tty_io_nonblock(tty, file)) { |
1035b63d PF |
558 | ret = -EAGAIN; |
559 | break; | |
04f378b1 | 560 | } |
1035b63d PF |
561 | |
562 | schedule(); | |
563 | ||
04f378b1 | 564 | if (signal_pending(current)) { |
1035b63d PF |
565 | ret = -EINTR; |
566 | break; | |
04f378b1 | 567 | } |
1da177e4 | 568 | } |
1035b63d PF |
569 | |
570 | remove_wait_queue(&tty->read_wait, &wait); | |
571 | __set_current_state(TASK_RUNNING); | |
572 | ||
1da177e4 LT |
573 | return ret; |
574 | ||
575 | } /* end of n_hdlc_tty_read() */ | |
576 | ||
577 | /** | |
578 | * n_hdlc_tty_write - write a single frame of data to device | |
579 | * @tty - pointer to associated tty device instance data | |
580 | * @file - pointer to file object data | |
581 | * @data - pointer to transmit data (one frame) | |
582 | * @count - size of transmit frame in bytes | |
583 | * | |
584 | * Returns the number of bytes written (or error code). | |
585 | */ | |
586 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
587 | const unsigned char *data, size_t count) | |
588 | { | |
589 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
590 | int error = 0; | |
591 | DECLARE_WAITQUEUE(wait, current); | |
592 | struct n_hdlc_buf *tbuf; | |
593 | ||
f3c2e277 JS |
594 | pr_debug("%s(%d)%s() called count=%zd\n", __FILE__, __LINE__, __func__, |
595 | count); | |
596 | ||
1da177e4 LT |
597 | /* Verify pointers */ |
598 | if (!n_hdlc) | |
599 | return -EIO; | |
600 | ||
601 | if (n_hdlc->magic != HDLC_MAGIC) | |
602 | return -EIO; | |
603 | ||
604 | /* verify frame size */ | |
605 | if (count > maxframe ) { | |
f3c2e277 JS |
606 | pr_debug("%s: truncating user packet from %zu to %d\n", |
607 | __func__, count, maxframe); | |
1da177e4 LT |
608 | count = maxframe; |
609 | } | |
610 | ||
611 | add_wait_queue(&tty->write_wait, &wait); | |
1035b63d PF |
612 | |
613 | for (;;) { | |
614 | set_current_state(TASK_INTERRUPTIBLE); | |
1da177e4 | 615 | |
1035b63d PF |
616 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); |
617 | if (tbuf) | |
618 | break; | |
619 | ||
c96cf923 | 620 | if (tty_io_nonblock(tty, file)) { |
c72f527c PF |
621 | error = -EAGAIN; |
622 | break; | |
623 | } | |
1da177e4 LT |
624 | schedule(); |
625 | ||
626 | n_hdlc = tty2n_hdlc (tty); | |
627 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || | |
628 | tty != n_hdlc->tty) { | |
629 | printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc); | |
630 | error = -EIO; | |
631 | break; | |
632 | } | |
633 | ||
634 | if (signal_pending(current)) { | |
635 | error = -EINTR; | |
636 | break; | |
637 | } | |
638 | } | |
639 | ||
1035b63d | 640 | __set_current_state(TASK_RUNNING); |
1da177e4 LT |
641 | remove_wait_queue(&tty->write_wait, &wait); |
642 | ||
643 | if (!error) { | |
644 | /* Retrieve the user's buffer */ | |
645 | memcpy(tbuf->buf, data, count); | |
646 | ||
647 | /* Send the data */ | |
648 | tbuf->count = error = count; | |
649 | n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf); | |
650 | n_hdlc_send_frames(n_hdlc,tty); | |
651 | } | |
1035b63d | 652 | |
1da177e4 LT |
653 | return error; |
654 | ||
655 | } /* end of n_hdlc_tty_write() */ | |
656 | ||
657 | /** | |
658 | * n_hdlc_tty_ioctl - process IOCTL system call for the tty device. | |
659 | * @tty - pointer to tty instance data | |
660 | * @file - pointer to open file object for device | |
661 | * @cmd - IOCTL command code | |
662 | * @arg - argument for IOCTL call (cmd dependent) | |
663 | * | |
664 | * Returns command dependent result. | |
665 | */ | |
666 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
667 | unsigned int cmd, unsigned long arg) | |
668 | { | |
669 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
670 | int error = 0; | |
671 | int count; | |
672 | unsigned long flags; | |
82f2341c AP |
673 | struct n_hdlc_buf *buf = NULL; |
674 | ||
f3c2e277 JS |
675 | pr_debug("%s(%d)%s() called %d\n", __FILE__, __LINE__, __func__, cmd); |
676 | ||
1da177e4 LT |
677 | /* Verify the status of the device */ |
678 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC) | |
679 | return -EBADF; | |
680 | ||
681 | switch (cmd) { | |
682 | case FIONREAD: | |
683 | /* report count of read data available */ | |
684 | /* in next available frame (if any) */ | |
685 | spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags); | |
82f2341c AP |
686 | buf = list_first_entry_or_null(&n_hdlc->rx_buf_list.list, |
687 | struct n_hdlc_buf, list_item); | |
688 | if (buf) | |
689 | count = buf->count; | |
1da177e4 LT |
690 | else |
691 | count = 0; | |
692 | spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags); | |
693 | error = put_user(count, (int __user *)arg); | |
694 | break; | |
695 | ||
696 | case TIOCOUTQ: | |
697 | /* get the pending tx byte count in the driver */ | |
f34d7a5b | 698 | count = tty_chars_in_buffer(tty); |
1da177e4 LT |
699 | /* add size of next output frame in queue */ |
700 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags); | |
82f2341c AP |
701 | buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list, |
702 | struct n_hdlc_buf, list_item); | |
703 | if (buf) | |
704 | count += buf->count; | |
1da177e4 LT |
705 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags); |
706 | error = put_user(count, (int __user *)arg); | |
707 | break; | |
708 | ||
be10eb75 PF |
709 | case TCFLSH: |
710 | switch (arg) { | |
711 | case TCIOFLUSH: | |
712 | case TCOFLUSH: | |
713 | flush_tx_queue(tty); | |
714 | } | |
361bf8a9 | 715 | /* fall through - to default */ |
be10eb75 | 716 | |
1da177e4 | 717 | default: |
47afa7a5 | 718 | error = n_tty_ioctl_helper(tty, file, cmd, arg); |
1da177e4 LT |
719 | break; |
720 | } | |
721 | return error; | |
722 | ||
723 | } /* end of n_hdlc_tty_ioctl() */ | |
724 | ||
725 | /** | |
726 | * n_hdlc_tty_poll - TTY callback for poll system call | |
727 | * @tty - pointer to tty instance data | |
728 | * @filp - pointer to open file object for device | |
729 | * @poll_table - wait queue for operations | |
730 | * | |
731 | * Determine which operations (read/write) will not block and return info | |
732 | * to caller. | |
733 | * Returns a bit mask containing info on which ops will not block. | |
734 | */ | |
afc9a42b | 735 | static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, |
1da177e4 LT |
736 | poll_table *wait) |
737 | { | |
738 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
afc9a42b | 739 | __poll_t mask = 0; |
1da177e4 | 740 | |
5f289514 JS |
741 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || tty != n_hdlc->tty) |
742 | return 0; | |
743 | ||
744 | /* | |
745 | * queue the current process into any wait queue that may awaken in the | |
746 | * future (read and write) | |
747 | */ | |
748 | poll_wait(filp, &tty->read_wait, wait); | |
749 | poll_wait(filp, &tty->write_wait, wait); | |
750 | ||
751 | /* set bits for operations that won't block */ | |
752 | if (!list_empty(&n_hdlc->rx_buf_list.list)) | |
753 | mask |= EPOLLIN | EPOLLRDNORM; /* readable */ | |
754 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
755 | mask |= EPOLLHUP; | |
756 | if (tty_hung_up_p(filp)) | |
757 | mask |= EPOLLHUP; | |
758 | if (!tty_is_writelocked(tty) && | |
759 | !list_empty(&n_hdlc->tx_free_buf_list.list)) | |
760 | mask |= EPOLLOUT | EPOLLWRNORM; /* writable */ | |
761 | ||
1da177e4 LT |
762 | return mask; |
763 | } /* end of n_hdlc_tty_poll() */ | |
764 | ||
765 | /** | |
766 | * n_hdlc_alloc - allocate an n_hdlc instance data structure | |
767 | * | |
768 | * Returns a pointer to newly created structure if success, otherwise %NULL | |
769 | */ | |
770 | static struct n_hdlc *n_hdlc_alloc(void) | |
771 | { | |
772 | struct n_hdlc_buf *buf; | |
773 | int i; | |
8e25f8ce | 774 | struct n_hdlc *n_hdlc = kzalloc(sizeof(*n_hdlc), GFP_KERNEL); |
1da177e4 LT |
775 | |
776 | if (!n_hdlc) | |
777 | return NULL; | |
778 | ||
e9b736d8 JS |
779 | spin_lock_init(&n_hdlc->rx_free_buf_list.spinlock); |
780 | spin_lock_init(&n_hdlc->tx_free_buf_list.spinlock); | |
781 | spin_lock_init(&n_hdlc->rx_buf_list.spinlock); | |
782 | spin_lock_init(&n_hdlc->tx_buf_list.spinlock); | |
82f2341c AP |
783 | |
784 | INIT_LIST_HEAD(&n_hdlc->rx_free_buf_list.list); | |
785 | INIT_LIST_HEAD(&n_hdlc->tx_free_buf_list.list); | |
786 | INIT_LIST_HEAD(&n_hdlc->rx_buf_list.list); | |
787 | INIT_LIST_HEAD(&n_hdlc->tx_buf_list.list); | |
788 | ||
1da177e4 LT |
789 | /* allocate free rx buffer list */ |
790 | for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) { | |
85f4c951 | 791 | buf = kmalloc(struct_size(buf, buf, maxframe), GFP_KERNEL); |
1da177e4 LT |
792 | if (buf) |
793 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf); | |
f3c2e277 JS |
794 | else |
795 | pr_debug("%s(%d)%s(), kmalloc() failed for rx buffer %d\n", | |
796 | __FILE__, __LINE__, __func__, i); | |
1da177e4 LT |
797 | } |
798 | ||
799 | /* allocate free tx buffer list */ | |
800 | for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) { | |
85f4c951 | 801 | buf = kmalloc(struct_size(buf, buf, maxframe), GFP_KERNEL); |
1da177e4 LT |
802 | if (buf) |
803 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf); | |
f3c2e277 JS |
804 | else |
805 | pr_debug("%s(%d)%s(), kmalloc() failed for tx buffer %d\n", | |
806 | __FILE__, __LINE__, __func__, i); | |
1da177e4 LT |
807 | } |
808 | ||
809 | /* Initialize the control block */ | |
810 | n_hdlc->magic = HDLC_MAGIC; | |
811 | n_hdlc->flags = 0; | |
812 | ||
813 | return n_hdlc; | |
814 | ||
815 | } /* end of n_hdlc_alloc() */ | |
816 | ||
82f2341c AP |
817 | /** |
818 | * n_hdlc_buf_return - put the HDLC buffer after the head of the specified list | |
819 | * @buf_list - pointer to the buffer list | |
820 | * @buf - pointer to the buffer | |
821 | */ | |
822 | static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, | |
823 | struct n_hdlc_buf *buf) | |
824 | { | |
825 | unsigned long flags; | |
826 | ||
827 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
828 | ||
829 | list_add(&buf->list_item, &buf_list->list); | |
830 | buf_list->count++; | |
831 | ||
832 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
833 | } | |
834 | ||
1da177e4 LT |
835 | /** |
836 | * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list | |
82f2341c | 837 | * @buf_list - pointer to buffer list |
1da177e4 LT |
838 | * @buf - pointer to buffer |
839 | */ | |
82f2341c | 840 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list, |
1da177e4 LT |
841 | struct n_hdlc_buf *buf) |
842 | { | |
843 | unsigned long flags; | |
82f2341c AP |
844 | |
845 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
846 | ||
847 | list_add_tail(&buf->list_item, &buf_list->list); | |
848 | buf_list->count++; | |
849 | ||
850 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
1da177e4 LT |
851 | } /* end of n_hdlc_buf_put() */ |
852 | ||
853 | /** | |
854 | * n_hdlc_buf_get - remove and return an HDLC buffer from list | |
82f2341c | 855 | * @buf_list - pointer to HDLC buffer list |
1da177e4 LT |
856 | * |
857 | * Remove and return an HDLC buffer from the head of the specified HDLC buffer | |
858 | * list. | |
859 | * Returns a pointer to HDLC buffer if available, otherwise %NULL. | |
860 | */ | |
82f2341c | 861 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list) |
1da177e4 LT |
862 | { |
863 | unsigned long flags; | |
864 | struct n_hdlc_buf *buf; | |
82f2341c AP |
865 | |
866 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
867 | ||
868 | buf = list_first_entry_or_null(&buf_list->list, | |
869 | struct n_hdlc_buf, list_item); | |
1da177e4 | 870 | if (buf) { |
82f2341c AP |
871 | list_del(&buf->list_item); |
872 | buf_list->count--; | |
1da177e4 | 873 | } |
82f2341c AP |
874 | |
875 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
1da177e4 | 876 | return buf; |
1da177e4 LT |
877 | } /* end of n_hdlc_buf_get() */ |
878 | ||
1da177e4 LT |
879 | static int __init n_hdlc_init(void) |
880 | { | |
881 | int status; | |
882 | ||
883 | /* range check maxframe arg */ | |
c549725f | 884 | maxframe = clamp(maxframe, 4096, MAX_HDLC_FRAME_SIZE); |
1da177e4 | 885 | |
1da177e4 LT |
886 | status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc); |
887 | if (!status) | |
cda3756c JS |
888 | pr_info("N_HDLC line discipline registered with maxframe=%d\n", |
889 | maxframe); | |
1da177e4 | 890 | else |
cda3756c JS |
891 | pr_err("N_HDLC: error registering line discipline: %d\n", |
892 | status); | |
1da177e4 | 893 | |
1da177e4 LT |
894 | return status; |
895 | ||
896 | } /* end of init_module() */ | |
897 | ||
1da177e4 LT |
898 | static void __exit n_hdlc_exit(void) |
899 | { | |
900 | /* Release tty registration of line discipline */ | |
64ccd715 | 901 | int status = tty_unregister_ldisc(N_HDLC); |
1da177e4 LT |
902 | |
903 | if (status) | |
aebe5fc3 JS |
904 | pr_err("N_HDLC: can't unregister line discipline (err = %d)\n", |
905 | status); | |
1da177e4 | 906 | else |
aebe5fc3 | 907 | pr_info("N_HDLC: line discipline unregistered\n"); |
1da177e4 LT |
908 | } |
909 | ||
910 | module_init(n_hdlc_init); | |
911 | module_exit(n_hdlc_exit); | |
912 | ||
913 | MODULE_LICENSE("GPL"); | |
914 | MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com"); | |
1da177e4 LT |
915 | module_param(maxframe, int, 0); |
916 | MODULE_ALIAS_LDISC(N_HDLC); |