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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 | |
43741e9b | 21 | * The device driver should accept the complete frame or none of |
1da177e4 LT |
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. | |
43741e9b | 42 | * |
1da177e4 LT |
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> |
5ffa6e34 | 103 | #include "tty.h" |
1da177e4 LT |
104 | |
105 | /* | |
106 | * Buffers for individual HDLC frames | |
107 | */ | |
43741e9b | 108 | #define MAX_HDLC_FRAME_SIZE 65535 |
1da177e4 LT |
109 | #define DEFAULT_RX_BUF_COUNT 10 |
110 | #define MAX_RX_BUF_COUNT 60 | |
be10eb75 | 111 | #define DEFAULT_TX_BUF_COUNT 3 |
1da177e4 LT |
112 | |
113 | struct n_hdlc_buf { | |
82f2341c | 114 | struct list_head list_item; |
1da177e4 | 115 | int count; |
85f4c951 | 116 | char buf[]; |
1da177e4 LT |
117 | }; |
118 | ||
1da177e4 | 119 | struct n_hdlc_buf_list { |
82f2341c | 120 | struct list_head list; |
1da177e4 LT |
121 | int count; |
122 | spinlock_t spinlock; | |
123 | }; | |
124 | ||
125 | /** | |
126 | * struct n_hdlc - per device instance data structure | |
724ac070 JS |
127 | * @magic: magic value for structure |
128 | * @tbusy: reentrancy flag for tx wakeup code | |
129 | * @woke_up: tx wakeup needs to be run again as it was called while @tbusy | |
130 | * @tx_buf_list: list of pending transmit frame buffers | |
131 | * @rx_buf_list: list of received frame buffers | |
132 | * @tx_free_buf_list: list unused transmit frame buffers | |
133 | * @rx_free_buf_list: list unused received frame buffers | |
1da177e4 LT |
134 | */ |
135 | struct n_hdlc { | |
136 | int magic; | |
0f238298 JS |
137 | bool tbusy; |
138 | bool woke_up; | |
1da177e4 LT |
139 | struct n_hdlc_buf_list tx_buf_list; |
140 | struct n_hdlc_buf_list rx_buf_list; | |
141 | struct n_hdlc_buf_list tx_free_buf_list; | |
142 | struct n_hdlc_buf_list rx_free_buf_list; | |
143 | }; | |
144 | ||
145 | /* | |
146 | * HDLC buffer list manipulation functions | |
147 | */ | |
82f2341c AP |
148 | static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, |
149 | struct n_hdlc_buf *buf); | |
1da177e4 LT |
150 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, |
151 | struct n_hdlc_buf *buf); | |
152 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list); | |
153 | ||
154 | /* Local functions */ | |
155 | ||
2bfb2b75 | 156 | static struct n_hdlc *n_hdlc_alloc(void); |
1da177e4 | 157 | |
1da177e4 LT |
158 | /* max frame size for memory allocations */ |
159 | static int maxframe = 4096; | |
160 | ||
be10eb75 PF |
161 | static void flush_rx_queue(struct tty_struct *tty) |
162 | { | |
75011682 | 163 | struct n_hdlc *n_hdlc = tty->disc_data; |
be10eb75 PF |
164 | struct n_hdlc_buf *buf; |
165 | ||
166 | while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list))) | |
167 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf); | |
168 | } | |
169 | ||
170 | static void flush_tx_queue(struct tty_struct *tty) | |
171 | { | |
75011682 | 172 | struct n_hdlc *n_hdlc = tty->disc_data; |
be10eb75 | 173 | struct n_hdlc_buf *buf; |
be10eb75 PF |
174 | |
175 | while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list))) | |
176 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf); | |
be10eb75 PF |
177 | } |
178 | ||
30fafd92 JS |
179 | static void n_hdlc_free_buf_list(struct n_hdlc_buf_list *list) |
180 | { | |
181 | struct n_hdlc_buf *buf; | |
182 | ||
183 | do { | |
184 | buf = n_hdlc_buf_get(list); | |
185 | kfree(buf); | |
186 | } while (buf); | |
187 | } | |
188 | ||
1da177e4 LT |
189 | /** |
190 | * n_hdlc_tty_close - line discipline close | |
724ac070 | 191 | * @tty: pointer to tty info structure |
1da177e4 LT |
192 | * |
193 | * Called when the line discipline is changed to something | |
194 | * else, the tty is closed, or the tty detects a hangup. | |
195 | */ | |
196 | static void n_hdlc_tty_close(struct tty_struct *tty) | |
197 | { | |
75011682 | 198 | struct n_hdlc *n_hdlc = tty->disc_data; |
1da177e4 | 199 | |
5f289514 | 200 | if (n_hdlc->magic != HDLC_MAGIC) { |
d86b05cb | 201 | pr_warn("n_hdlc: trying to close unopened tty!\n"); |
5f289514 JS |
202 | return; |
203 | } | |
1da177e4 | 204 | #if defined(TTY_NO_WRITE_SPLIT) |
8d79bb5c | 205 | clear_bit(TTY_NO_WRITE_SPLIT, &tty->flags); |
1da177e4 | 206 | #endif |
5f289514 | 207 | tty->disc_data = NULL; |
43e784ec JS |
208 | |
209 | /* Ensure that the n_hdlcd process is not hanging on select()/poll() */ | |
210 | wake_up_interruptible(&tty->read_wait); | |
211 | wake_up_interruptible(&tty->write_wait); | |
212 | ||
213 | n_hdlc_free_buf_list(&n_hdlc->rx_free_buf_list); | |
214 | n_hdlc_free_buf_list(&n_hdlc->tx_free_buf_list); | |
215 | n_hdlc_free_buf_list(&n_hdlc->rx_buf_list); | |
216 | n_hdlc_free_buf_list(&n_hdlc->tx_buf_list); | |
217 | kfree(n_hdlc); | |
1da177e4 LT |
218 | } /* end of n_hdlc_tty_close() */ |
219 | ||
220 | /** | |
221 | * n_hdlc_tty_open - called when line discipline changed to n_hdlc | |
724ac070 | 222 | * @tty: pointer to tty info structure |
1da177e4 LT |
223 | * |
224 | * Returns 0 if success, otherwise error code | |
225 | */ | |
2bfb2b75 | 226 | static int n_hdlc_tty_open(struct tty_struct *tty) |
1da177e4 | 227 | { |
75011682 | 228 | struct n_hdlc *n_hdlc = tty->disc_data; |
1da177e4 | 229 | |
b18d1c2e | 230 | pr_debug("%s() called (device=%s)\n", __func__, tty->name); |
f3c2e277 | 231 | |
1da177e4 LT |
232 | /* There should not be an existing table for this slot. */ |
233 | if (n_hdlc) { | |
d86b05cb | 234 | pr_err("%s: tty already associated!\n", __func__); |
1da177e4 LT |
235 | return -EEXIST; |
236 | } | |
43741e9b | 237 | |
1da177e4 LT |
238 | n_hdlc = n_hdlc_alloc(); |
239 | if (!n_hdlc) { | |
d86b05cb | 240 | pr_err("%s: n_hdlc_alloc failed\n", __func__); |
1da177e4 LT |
241 | return -ENFILE; |
242 | } | |
43741e9b | 243 | |
1da177e4 | 244 | tty->disc_data = n_hdlc; |
33f0f88f | 245 | tty->receive_room = 65536; |
43741e9b | 246 | |
1da177e4 | 247 | /* change tty_io write() to not split large writes into 8K chunks */ |
8d79bb5c | 248 | set_bit(TTY_NO_WRITE_SPLIT, &tty->flags); |
43741e9b | 249 | |
be10eb75 | 250 | /* flush receive data from driver */ |
f34d7a5b | 251 | tty_driver_flush_buffer(tty); |
66c3bdf1 | 252 | |
1da177e4 | 253 | return 0; |
43741e9b | 254 | |
1da177e4 LT |
255 | } /* end of n_tty_hdlc_open() */ |
256 | ||
257 | /** | |
258 | * n_hdlc_send_frames - send frames on pending send buffer list | |
724ac070 JS |
259 | * @n_hdlc: pointer to ldisc instance data |
260 | * @tty: pointer to tty instance data | |
1da177e4 LT |
261 | * |
262 | * Send frames on pending send buffer list until the driver does not accept a | |
263 | * frame (busy) this function is called after adding a frame to the send buffer | |
264 | * list and by the tty wakeup callback. | |
265 | */ | |
266 | static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) | |
267 | { | |
268 | register int actual; | |
269 | unsigned long flags; | |
270 | struct n_hdlc_buf *tbuf; | |
271 | ||
43741e9b JS |
272 | check_again: |
273 | ||
274 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
1da177e4 | 275 | if (n_hdlc->tbusy) { |
0f238298 JS |
276 | n_hdlc->woke_up = true; |
277 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
1da177e4 LT |
278 | return; |
279 | } | |
0f238298 JS |
280 | n_hdlc->tbusy = true; |
281 | n_hdlc->woke_up = false; | |
1da177e4 LT |
282 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); |
283 | ||
82f2341c | 284 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); |
1da177e4 | 285 | while (tbuf) { |
b18d1c2e | 286 | pr_debug("sending frame %p, count=%d\n", tbuf, tbuf->count); |
f3c2e277 | 287 | |
1da177e4 | 288 | /* Send the next block of data to device */ |
7962fce9 | 289 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
f34d7a5b | 290 | actual = tty->ops->write(tty, tbuf->buf, tbuf->count); |
b0fed314 JS |
291 | |
292 | /* rollback was possible and has been done */ | |
293 | if (actual == -ERESTARTSYS) { | |
82f2341c | 294 | n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); |
b0fed314 JS |
295 | break; |
296 | } | |
1da177e4 LT |
297 | /* if transmit error, throw frame away by */ |
298 | /* pretending it was accepted by driver */ | |
299 | if (actual < 0) | |
300 | actual = tbuf->count; | |
43741e9b | 301 | |
1da177e4 | 302 | if (actual == tbuf->count) { |
b18d1c2e | 303 | pr_debug("frame %p completed\n", tbuf); |
f3c2e277 | 304 | |
1da177e4 LT |
305 | /* free current transmit buffer */ |
306 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf); | |
82f2341c | 307 | |
1da177e4 LT |
308 | /* wait up sleeping writers */ |
309 | wake_up_interruptible(&tty->write_wait); | |
43741e9b | 310 | |
1da177e4 LT |
311 | /* get next pending transmit buffer */ |
312 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
313 | } else { | |
b18d1c2e | 314 | pr_debug("frame %p pending\n", tbuf); |
82f2341c AP |
315 | |
316 | /* | |
317 | * the buffer was not accepted by driver, | |
318 | * return it back into tx queue | |
319 | */ | |
320 | n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); | |
1da177e4 LT |
321 | break; |
322 | } | |
323 | } | |
43741e9b | 324 | |
1da177e4 | 325 | if (!tbuf) |
7962fce9 | 326 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
43741e9b | 327 | |
1da177e4 LT |
328 | /* Clear the re-entry flag */ |
329 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
0f238298 | 330 | n_hdlc->tbusy = false; |
43741e9b JS |
331 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); |
332 | ||
333 | if (n_hdlc->woke_up) | |
334 | goto check_again; | |
1da177e4 LT |
335 | } /* end of n_hdlc_send_frames() */ |
336 | ||
337 | /** | |
338 | * n_hdlc_tty_wakeup - Callback for transmit wakeup | |
724ac070 | 339 | * @tty: pointer to associated tty instance data |
1da177e4 LT |
340 | * |
341 | * Called when low level device driver can accept more send data. | |
342 | */ | |
343 | static void n_hdlc_tty_wakeup(struct tty_struct *tty) | |
344 | { | |
75011682 | 345 | struct n_hdlc *n_hdlc = tty->disc_data; |
1da177e4 | 346 | |
2bfb2b75 | 347 | n_hdlc_send_frames(n_hdlc, tty); |
1da177e4 LT |
348 | } /* end of n_hdlc_tty_wakeup() */ |
349 | ||
1da177e4 LT |
350 | /** |
351 | * n_hdlc_tty_receive - Called by tty driver when receive data is available | |
724ac070 JS |
352 | * @tty: pointer to tty instance data |
353 | * @data: pointer to received data | |
354 | * @flags: pointer to flags for data | |
355 | * @count: count of received data in bytes | |
1da177e4 LT |
356 | * |
357 | * Called by tty low level driver when receive data is available. Data is | |
358 | * interpreted as one HDLC frame. | |
359 | */ | |
55db4c64 | 360 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data, |
0f3dcf3b | 361 | const char *flags, int count) |
1da177e4 | 362 | { |
75011682 | 363 | register struct n_hdlc *n_hdlc = tty->disc_data; |
1da177e4 LT |
364 | register struct n_hdlc_buf *buf; |
365 | ||
b18d1c2e | 366 | pr_debug("%s() called count=%d\n", __func__, count); |
f3c2e277 | 367 | |
1da177e4 LT |
368 | /* verify line is using HDLC discipline */ |
369 | if (n_hdlc->magic != HDLC_MAGIC) { | |
b18d1c2e | 370 | pr_err("line not using HDLC discipline\n"); |
55db4c64 | 371 | return; |
1da177e4 | 372 | } |
43741e9b | 373 | |
1283c721 | 374 | if (count > maxframe) { |
b18d1c2e | 375 | pr_debug("rx count>maxframesize, data discarded\n"); |
55db4c64 | 376 | return; |
1da177e4 LT |
377 | } |
378 | ||
43741e9b | 379 | /* get a free HDLC buffer */ |
1da177e4 LT |
380 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); |
381 | if (!buf) { | |
80967ff2 JS |
382 | /* |
383 | * no buffers in free list, attempt to allocate another rx | |
384 | * buffer unless the maximum count has been reached | |
385 | */ | |
1da177e4 | 386 | if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT) |
85f4c951 GS |
387 | buf = kmalloc(struct_size(buf, buf, maxframe), |
388 | GFP_ATOMIC); | |
1da177e4 | 389 | } |
43741e9b | 390 | |
1da177e4 | 391 | if (!buf) { |
b18d1c2e | 392 | pr_debug("no more rx buffers, data discarded\n"); |
55db4c64 | 393 | return; |
1da177e4 | 394 | } |
43741e9b | 395 | |
1da177e4 | 396 | /* copy received data to HDLC buffer */ |
8d79bb5c | 397 | memcpy(buf->buf, data, count); |
1283c721 | 398 | buf->count = count; |
1da177e4 LT |
399 | |
400 | /* add HDLC buffer to list of received frames */ | |
401 | n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf); | |
43741e9b | 402 | |
1da177e4 | 403 | /* wake up any blocked reads and perform async signalling */ |
2bfb2b75 | 404 | wake_up_interruptible(&tty->read_wait); |
df6de639 JS |
405 | if (tty->fasync != NULL) |
406 | kill_fasync(&tty->fasync, SIGIO, POLL_IN); | |
1da177e4 LT |
407 | |
408 | } /* end of n_hdlc_tty_receive() */ | |
409 | ||
410 | /** | |
4a4efbde | 411 | * n_hdlc_tty_read - Called to retrieve one frame of data (if available) |
724ac070 JS |
412 | * @tty: pointer to tty instance data |
413 | * @file: pointer to open file object | |
414 | * @buf: pointer to returned data buffer | |
415 | * @nr: size of returned data buffer | |
43741e9b | 416 | * |
1da177e4 LT |
417 | * Returns the number of bytes returned or error code. |
418 | */ | |
419 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
3b830a9c LT |
420 | __u8 *kbuf, size_t nr, |
421 | void **cookie, unsigned long offset) | |
1da177e4 | 422 | { |
75011682 | 423 | struct n_hdlc *n_hdlc = tty->disc_data; |
1035b63d | 424 | int ret = 0; |
1da177e4 | 425 | struct n_hdlc_buf *rbuf; |
1035b63d | 426 | DECLARE_WAITQUEUE(wait, current); |
1da177e4 | 427 | |
3b830a9c LT |
428 | /* Is this a repeated call for an rbuf we already found earlier? */ |
429 | rbuf = *cookie; | |
430 | if (rbuf) | |
431 | goto have_rbuf; | |
432 | ||
1035b63d | 433 | add_wait_queue(&tty->read_wait, &wait); |
04f378b1 | 434 | |
1da177e4 | 435 | for (;;) { |
0f40fbbc | 436 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { |
1035b63d PF |
437 | ret = -EIO; |
438 | break; | |
04f378b1 | 439 | } |
1035b63d PF |
440 | if (tty_hung_up_p(file)) |
441 | break; | |
1da177e4 | 442 | |
1035b63d | 443 | set_current_state(TASK_INTERRUPTIBLE); |
1da177e4 LT |
444 | |
445 | rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
3b830a9c | 446 | if (rbuf) |
1da177e4 | 447 | break; |
43741e9b | 448 | |
1da177e4 | 449 | /* no data */ |
c96cf923 | 450 | if (tty_io_nonblock(tty, file)) { |
1035b63d PF |
451 | ret = -EAGAIN; |
452 | break; | |
04f378b1 | 453 | } |
1035b63d PF |
454 | |
455 | schedule(); | |
456 | ||
04f378b1 | 457 | if (signal_pending(current)) { |
1035b63d PF |
458 | ret = -EINTR; |
459 | break; | |
04f378b1 | 460 | } |
1da177e4 | 461 | } |
1035b63d PF |
462 | |
463 | remove_wait_queue(&tty->read_wait, &wait); | |
464 | __set_current_state(TASK_RUNNING); | |
465 | ||
3b830a9c LT |
466 | if (!rbuf) |
467 | return ret; | |
468 | *cookie = rbuf; | |
469 | ||
470 | have_rbuf: | |
471 | /* Have we used it up entirely? */ | |
472 | if (offset >= rbuf->count) | |
473 | goto done_with_rbuf; | |
474 | ||
475 | /* More data to go, but can't copy any more? EOVERFLOW */ | |
476 | ret = -EOVERFLOW; | |
477 | if (!nr) | |
478 | goto done_with_rbuf; | |
479 | ||
480 | /* Copy as much data as possible */ | |
481 | ret = rbuf->count - offset; | |
482 | if (ret > nr) | |
483 | ret = nr; | |
484 | memcpy(kbuf, rbuf->buf+offset, ret); | |
485 | offset += ret; | |
486 | ||
487 | /* If we still have data left, we leave the rbuf in the cookie */ | |
488 | if (offset < rbuf->count) | |
489 | return ret; | |
490 | ||
491 | done_with_rbuf: | |
492 | *cookie = NULL; | |
493 | ||
494 | if (n_hdlc->rx_free_buf_list.count > DEFAULT_RX_BUF_COUNT) | |
495 | kfree(rbuf); | |
496 | else | |
497 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf); | |
498 | ||
1da177e4 | 499 | return ret; |
43741e9b | 500 | |
1da177e4 LT |
501 | } /* end of n_hdlc_tty_read() */ |
502 | ||
503 | /** | |
504 | * n_hdlc_tty_write - write a single frame of data to device | |
724ac070 JS |
505 | * @tty: pointer to associated tty device instance data |
506 | * @file: pointer to file object data | |
507 | * @data: pointer to transmit data (one frame) | |
508 | * @count: size of transmit frame in bytes | |
43741e9b | 509 | * |
1da177e4 LT |
510 | * Returns the number of bytes written (or error code). |
511 | */ | |
512 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
513 | const unsigned char *data, size_t count) | |
514 | { | |
75011682 | 515 | struct n_hdlc *n_hdlc = tty->disc_data; |
1da177e4 LT |
516 | int error = 0; |
517 | DECLARE_WAITQUEUE(wait, current); | |
518 | struct n_hdlc_buf *tbuf; | |
519 | ||
b18d1c2e | 520 | pr_debug("%s() called count=%zd\n", __func__, count); |
f3c2e277 | 521 | |
1da177e4 LT |
522 | if (n_hdlc->magic != HDLC_MAGIC) |
523 | return -EIO; | |
524 | ||
525 | /* verify frame size */ | |
1283c721 | 526 | if (count > maxframe) { |
f3c2e277 JS |
527 | pr_debug("%s: truncating user packet from %zu to %d\n", |
528 | __func__, count, maxframe); | |
1da177e4 LT |
529 | count = maxframe; |
530 | } | |
43741e9b | 531 | |
1da177e4 | 532 | add_wait_queue(&tty->write_wait, &wait); |
1035b63d PF |
533 | |
534 | for (;;) { | |
535 | set_current_state(TASK_INTERRUPTIBLE); | |
43741e9b | 536 | |
1035b63d PF |
537 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); |
538 | if (tbuf) | |
539 | break; | |
540 | ||
c96cf923 | 541 | if (tty_io_nonblock(tty, file)) { |
c72f527c PF |
542 | error = -EAGAIN; |
543 | break; | |
544 | } | |
1da177e4 | 545 | schedule(); |
844cc5f9 | 546 | |
1da177e4 LT |
547 | if (signal_pending(current)) { |
548 | error = -EINTR; | |
549 | break; | |
550 | } | |
551 | } | |
552 | ||
1035b63d | 553 | __set_current_state(TASK_RUNNING); |
1da177e4 LT |
554 | remove_wait_queue(&tty->write_wait, &wait); |
555 | ||
43741e9b | 556 | if (!error) { |
1da177e4 LT |
557 | /* Retrieve the user's buffer */ |
558 | memcpy(tbuf->buf, data, count); | |
559 | ||
560 | /* Send the data */ | |
561 | tbuf->count = error = count; | |
8d79bb5c JS |
562 | n_hdlc_buf_put(&n_hdlc->tx_buf_list, tbuf); |
563 | n_hdlc_send_frames(n_hdlc, tty); | |
1da177e4 | 564 | } |
1035b63d | 565 | |
1da177e4 | 566 | return error; |
43741e9b | 567 | |
1da177e4 LT |
568 | } /* end of n_hdlc_tty_write() */ |
569 | ||
570 | /** | |
571 | * n_hdlc_tty_ioctl - process IOCTL system call for the tty device. | |
724ac070 JS |
572 | * @tty: pointer to tty instance data |
573 | * @file: pointer to open file object for device | |
574 | * @cmd: IOCTL command code | |
575 | * @arg: argument for IOCTL call (cmd dependent) | |
1da177e4 LT |
576 | * |
577 | * Returns command dependent result. | |
578 | */ | |
579 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
580 | unsigned int cmd, unsigned long arg) | |
581 | { | |
75011682 | 582 | struct n_hdlc *n_hdlc = tty->disc_data; |
1da177e4 LT |
583 | int error = 0; |
584 | int count; | |
585 | unsigned long flags; | |
82f2341c AP |
586 | struct n_hdlc_buf *buf = NULL; |
587 | ||
b18d1c2e | 588 | pr_debug("%s() called %d\n", __func__, cmd); |
f3c2e277 | 589 | |
1da177e4 | 590 | /* Verify the status of the device */ |
844cc5f9 | 591 | if (n_hdlc->magic != HDLC_MAGIC) |
1da177e4 LT |
592 | return -EBADF; |
593 | ||
594 | switch (cmd) { | |
595 | case FIONREAD: | |
596 | /* report count of read data available */ | |
597 | /* in next available frame (if any) */ | |
8d79bb5c | 598 | spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock, flags); |
82f2341c AP |
599 | buf = list_first_entry_or_null(&n_hdlc->rx_buf_list.list, |
600 | struct n_hdlc_buf, list_item); | |
601 | if (buf) | |
602 | count = buf->count; | |
1da177e4 LT |
603 | else |
604 | count = 0; | |
8d79bb5c | 605 | spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock, flags); |
1da177e4 LT |
606 | error = put_user(count, (int __user *)arg); |
607 | break; | |
608 | ||
609 | case TIOCOUTQ: | |
610 | /* get the pending tx byte count in the driver */ | |
f34d7a5b | 611 | count = tty_chars_in_buffer(tty); |
1da177e4 | 612 | /* add size of next output frame in queue */ |
8d79bb5c | 613 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); |
82f2341c AP |
614 | buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list, |
615 | struct n_hdlc_buf, list_item); | |
616 | if (buf) | |
617 | count += buf->count; | |
8d79bb5c | 618 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); |
1da177e4 LT |
619 | error = put_user(count, (int __user *)arg); |
620 | break; | |
621 | ||
be10eb75 PF |
622 | case TCFLSH: |
623 | switch (arg) { | |
624 | case TCIOFLUSH: | |
625 | case TCOFLUSH: | |
626 | flush_tx_queue(tty); | |
627 | } | |
df561f66 | 628 | fallthrough; /* to default */ |
be10eb75 | 629 | |
1da177e4 | 630 | default: |
47afa7a5 | 631 | error = n_tty_ioctl_helper(tty, file, cmd, arg); |
1da177e4 LT |
632 | break; |
633 | } | |
634 | return error; | |
43741e9b | 635 | |
1da177e4 LT |
636 | } /* end of n_hdlc_tty_ioctl() */ |
637 | ||
638 | /** | |
639 | * n_hdlc_tty_poll - TTY callback for poll system call | |
724ac070 JS |
640 | * @tty: pointer to tty instance data |
641 | * @filp: pointer to open file object for device | |
642 | * @wait: wait queue for operations | |
43741e9b | 643 | * |
1da177e4 LT |
644 | * Determine which operations (read/write) will not block and return info |
645 | * to caller. | |
646 | * Returns a bit mask containing info on which ops will not block. | |
647 | */ | |
afc9a42b | 648 | static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, |
1da177e4 LT |
649 | poll_table *wait) |
650 | { | |
75011682 | 651 | struct n_hdlc *n_hdlc = tty->disc_data; |
afc9a42b | 652 | __poll_t mask = 0; |
1da177e4 | 653 | |
844cc5f9 | 654 | if (n_hdlc->magic != HDLC_MAGIC) |
5f289514 JS |
655 | return 0; |
656 | ||
657 | /* | |
658 | * queue the current process into any wait queue that may awaken in the | |
659 | * future (read and write) | |
660 | */ | |
661 | poll_wait(filp, &tty->read_wait, wait); | |
662 | poll_wait(filp, &tty->write_wait, wait); | |
663 | ||
664 | /* set bits for operations that won't block */ | |
665 | if (!list_empty(&n_hdlc->rx_buf_list.list)) | |
666 | mask |= EPOLLIN | EPOLLRDNORM; /* readable */ | |
667 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
668 | mask |= EPOLLHUP; | |
669 | if (tty_hung_up_p(filp)) | |
670 | mask |= EPOLLHUP; | |
671 | if (!tty_is_writelocked(tty) && | |
672 | !list_empty(&n_hdlc->tx_free_buf_list.list)) | |
673 | mask |= EPOLLOUT | EPOLLWRNORM; /* writable */ | |
674 | ||
1da177e4 LT |
675 | return mask; |
676 | } /* end of n_hdlc_tty_poll() */ | |
677 | ||
740708ab JS |
678 | static void n_hdlc_alloc_buf(struct n_hdlc_buf_list *list, unsigned int count, |
679 | const char *name) | |
680 | { | |
681 | struct n_hdlc_buf *buf; | |
682 | unsigned int i; | |
683 | ||
684 | for (i = 0; i < count; i++) { | |
685 | buf = kmalloc(struct_size(buf, buf, maxframe), GFP_KERNEL); | |
686 | if (!buf) { | |
b18d1c2e JS |
687 | pr_debug("%s(), kmalloc() failed for %s buffer %u\n", |
688 | __func__, name, i); | |
740708ab JS |
689 | return; |
690 | } | |
691 | n_hdlc_buf_put(list, buf); | |
692 | } | |
693 | } | |
694 | ||
1da177e4 LT |
695 | /** |
696 | * n_hdlc_alloc - allocate an n_hdlc instance data structure | |
697 | * | |
698 | * Returns a pointer to newly created structure if success, otherwise %NULL | |
699 | */ | |
700 | static struct n_hdlc *n_hdlc_alloc(void) | |
701 | { | |
8e25f8ce | 702 | struct n_hdlc *n_hdlc = kzalloc(sizeof(*n_hdlc), GFP_KERNEL); |
1da177e4 LT |
703 | |
704 | if (!n_hdlc) | |
705 | return NULL; | |
706 | ||
e9b736d8 JS |
707 | spin_lock_init(&n_hdlc->rx_free_buf_list.spinlock); |
708 | spin_lock_init(&n_hdlc->tx_free_buf_list.spinlock); | |
709 | spin_lock_init(&n_hdlc->rx_buf_list.spinlock); | |
710 | spin_lock_init(&n_hdlc->tx_buf_list.spinlock); | |
82f2341c AP |
711 | |
712 | INIT_LIST_HEAD(&n_hdlc->rx_free_buf_list.list); | |
713 | INIT_LIST_HEAD(&n_hdlc->tx_free_buf_list.list); | |
714 | INIT_LIST_HEAD(&n_hdlc->rx_buf_list.list); | |
715 | INIT_LIST_HEAD(&n_hdlc->tx_buf_list.list); | |
716 | ||
740708ab JS |
717 | n_hdlc_alloc_buf(&n_hdlc->rx_free_buf_list, DEFAULT_RX_BUF_COUNT, "rx"); |
718 | n_hdlc_alloc_buf(&n_hdlc->tx_free_buf_list, DEFAULT_TX_BUF_COUNT, "tx"); | |
719 | ||
1da177e4 LT |
720 | /* Initialize the control block */ |
721 | n_hdlc->magic = HDLC_MAGIC; | |
a1274b26 | 722 | |
1da177e4 | 723 | return n_hdlc; |
43741e9b | 724 | |
1da177e4 LT |
725 | } /* end of n_hdlc_alloc() */ |
726 | ||
82f2341c AP |
727 | /** |
728 | * n_hdlc_buf_return - put the HDLC buffer after the head of the specified list | |
724ac070 JS |
729 | * @buf_list: pointer to the buffer list |
730 | * @buf: pointer to the buffer | |
82f2341c AP |
731 | */ |
732 | static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, | |
733 | struct n_hdlc_buf *buf) | |
734 | { | |
735 | unsigned long flags; | |
736 | ||
737 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
738 | ||
739 | list_add(&buf->list_item, &buf_list->list); | |
740 | buf_list->count++; | |
741 | ||
742 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
743 | } | |
744 | ||
1da177e4 LT |
745 | /** |
746 | * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list | |
724ac070 JS |
747 | * @buf_list: pointer to buffer list |
748 | * @buf: pointer to buffer | |
1da177e4 | 749 | */ |
82f2341c | 750 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list, |
1da177e4 LT |
751 | struct n_hdlc_buf *buf) |
752 | { | |
753 | unsigned long flags; | |
82f2341c AP |
754 | |
755 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
756 | ||
757 | list_add_tail(&buf->list_item, &buf_list->list); | |
758 | buf_list->count++; | |
759 | ||
760 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
1da177e4 LT |
761 | } /* end of n_hdlc_buf_put() */ |
762 | ||
763 | /** | |
764 | * n_hdlc_buf_get - remove and return an HDLC buffer from list | |
724ac070 | 765 | * @buf_list: pointer to HDLC buffer list |
43741e9b | 766 | * |
1da177e4 LT |
767 | * Remove and return an HDLC buffer from the head of the specified HDLC buffer |
768 | * list. | |
769 | * Returns a pointer to HDLC buffer if available, otherwise %NULL. | |
770 | */ | |
82f2341c | 771 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list) |
1da177e4 LT |
772 | { |
773 | unsigned long flags; | |
774 | struct n_hdlc_buf *buf; | |
82f2341c AP |
775 | |
776 | spin_lock_irqsave(&buf_list->spinlock, flags); | |
777 | ||
778 | buf = list_first_entry_or_null(&buf_list->list, | |
779 | struct n_hdlc_buf, list_item); | |
1da177e4 | 780 | if (buf) { |
82f2341c AP |
781 | list_del(&buf->list_item); |
782 | buf_list->count--; | |
1da177e4 | 783 | } |
82f2341c AP |
784 | |
785 | spin_unlock_irqrestore(&buf_list->spinlock, flags); | |
1da177e4 | 786 | return buf; |
1da177e4 LT |
787 | } /* end of n_hdlc_buf_get() */ |
788 | ||
edee649f JS |
789 | static struct tty_ldisc_ops n_hdlc_ldisc = { |
790 | .owner = THIS_MODULE, | |
edee649f JS |
791 | .name = "hdlc", |
792 | .open = n_hdlc_tty_open, | |
793 | .close = n_hdlc_tty_close, | |
794 | .read = n_hdlc_tty_read, | |
795 | .write = n_hdlc_tty_write, | |
796 | .ioctl = n_hdlc_tty_ioctl, | |
797 | .poll = n_hdlc_tty_poll, | |
798 | .receive_buf = n_hdlc_tty_receive, | |
799 | .write_wakeup = n_hdlc_tty_wakeup, | |
800 | .flush_buffer = flush_rx_queue, | |
801 | }; | |
802 | ||
1da177e4 LT |
803 | static int __init n_hdlc_init(void) |
804 | { | |
805 | int status; | |
806 | ||
807 | /* range check maxframe arg */ | |
c549725f | 808 | maxframe = clamp(maxframe, 4096, MAX_HDLC_FRAME_SIZE); |
1da177e4 | 809 | |
1da177e4 LT |
810 | status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc); |
811 | if (!status) | |
cda3756c JS |
812 | pr_info("N_HDLC line discipline registered with maxframe=%d\n", |
813 | maxframe); | |
1da177e4 | 814 | else |
cda3756c JS |
815 | pr_err("N_HDLC: error registering line discipline: %d\n", |
816 | status); | |
1da177e4 | 817 | |
1da177e4 | 818 | return status; |
43741e9b | 819 | |
1da177e4 LT |
820 | } /* end of init_module() */ |
821 | ||
1da177e4 LT |
822 | static void __exit n_hdlc_exit(void) |
823 | { | |
824 | /* Release tty registration of line discipline */ | |
64ccd715 | 825 | int status = tty_unregister_ldisc(N_HDLC); |
1da177e4 LT |
826 | |
827 | if (status) | |
aebe5fc3 JS |
828 | pr_err("N_HDLC: can't unregister line discipline (err = %d)\n", |
829 | status); | |
1da177e4 | 830 | else |
aebe5fc3 | 831 | pr_info("N_HDLC: line discipline unregistered\n"); |
1da177e4 LT |
832 | } |
833 | ||
834 | module_init(n_hdlc_init); | |
835 | module_exit(n_hdlc_exit); | |
836 | ||
837 | MODULE_LICENSE("GPL"); | |
838 | MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com"); | |
1da177e4 LT |
839 | module_param(maxframe, int, 0); |
840 | MODULE_ALIAS_LDISC(N_HDLC); |