1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/types.h>
3 #include <linux/tty.h>
4 #include <linux/tty_flip.h>
5 #include <linux/slab.h>
6
7 #include "speakup.h"
8 #include "spk_types.h"
9 #include "spk_priv.h"
10
11 struct spk_ldisc_data {
12 char buf;
13 struct completion completion;
14 bool buf_free;
15 struct spk_synth *synth;
16 };
17
18 /*
19 * This allows to catch within spk_ttyio_ldisc_open whether it is getting set
20 * on for a speakup-driven device.
21 */
22 static struct tty_struct *speakup_tty;
23 /* This mutex serializes the use of such global speakup_tty variable */
24 static DEFINE_MUTEX(speakup_tty_mutex);
25
ser_to_dev(int ser,dev_t * dev_no)26 static int ser_to_dev(int ser, dev_t *dev_no)
27 {
28 if (ser < 0 || ser > (255 - 64)) {
29 pr_err("speakup: Invalid ser param. Must be between 0 and 191 inclusive.\n");
30 return -EINVAL;
31 }
32
33 *dev_no = MKDEV(4, (64 + ser));
34 return 0;
35 }
36
get_dev_to_use(struct spk_synth * synth,dev_t * dev_no)37 static int get_dev_to_use(struct spk_synth *synth, dev_t *dev_no)
38 {
39 /* use ser only when dev is not specified */
40 if (strcmp(synth->dev_name, SYNTH_DEFAULT_DEV) ||
41 synth->ser == SYNTH_DEFAULT_SER)
42 return tty_dev_name_to_number(synth->dev_name, dev_no);
43
44 return ser_to_dev(synth->ser, dev_no);
45 }
46
spk_ttyio_ldisc_open(struct tty_struct * tty)47 static int spk_ttyio_ldisc_open(struct tty_struct *tty)
48 {
49 struct spk_ldisc_data *ldisc_data;
50
51 if (tty != speakup_tty)
52 /* Somebody tried to use this line discipline outside speakup */
53 return -ENODEV;
54
55 if (!tty->ops->write)
56 return -EOPNOTSUPP;
57
58 ldisc_data = kmalloc(sizeof(*ldisc_data), GFP_KERNEL);
59 if (!ldisc_data)
60 return -ENOMEM;
61
62 init_completion(&ldisc_data->completion);
63 ldisc_data->buf_free = true;
64 tty->disc_data = ldisc_data;
65
66 return 0;
67 }
68
spk_ttyio_ldisc_close(struct tty_struct * tty)69 static void spk_ttyio_ldisc_close(struct tty_struct *tty)
70 {
71 kfree(tty->disc_data);
72 }
73
spk_ttyio_receive_buf2(struct tty_struct * tty,const u8 * cp,const u8 * fp,size_t count)74 static size_t spk_ttyio_receive_buf2(struct tty_struct *tty, const u8 *cp,
75 const u8 *fp, size_t count)
76 {
77 struct spk_ldisc_data *ldisc_data = tty->disc_data;
78 struct spk_synth *synth = ldisc_data->synth;
79
80 if (synth->read_buff_add) {
81 unsigned int i;
82
83 for (i = 0; i < count; i++)
84 synth->read_buff_add(cp[i]);
85
86 return count;
87 }
88
89 if (!ldisc_data->buf_free)
90 /* ttyio_in will tty_flip_buffer_push */
91 return 0;
92
93 /* Make sure the consumer has read buf before we have seen
94 * buf_free == true and overwrite buf
95 */
96 mb();
97
98 ldisc_data->buf = cp[0];
99 ldisc_data->buf_free = false;
100 complete(&ldisc_data->completion);
101
102 return 1;
103 }
104
105 static struct tty_ldisc_ops spk_ttyio_ldisc_ops = {
106 .owner = THIS_MODULE,
107 .num = N_SPEAKUP,
108 .name = "speakup_ldisc",
109 .open = spk_ttyio_ldisc_open,
110 .close = spk_ttyio_ldisc_close,
111 .receive_buf2 = spk_ttyio_receive_buf2,
112 };
113
114 static int spk_ttyio_out(struct spk_synth *in_synth, const char ch);
115 static int spk_ttyio_out_unicode(struct spk_synth *in_synth, u16 ch);
116 static void spk_ttyio_send_xchar(struct spk_synth *in_synth, char ch);
117 static void spk_ttyio_tiocmset(struct spk_synth *in_synth, unsigned int set, unsigned int clear);
118 static unsigned char spk_ttyio_in(struct spk_synth *in_synth);
119 static unsigned char spk_ttyio_in_nowait(struct spk_synth *in_synth);
120 static void spk_ttyio_flush_buffer(struct spk_synth *in_synth);
121 static int spk_ttyio_wait_for_xmitr(struct spk_synth *in_synth);
122
123 struct spk_io_ops spk_ttyio_ops = {
124 .synth_out = spk_ttyio_out,
125 .synth_out_unicode = spk_ttyio_out_unicode,
126 .send_xchar = spk_ttyio_send_xchar,
127 .tiocmset = spk_ttyio_tiocmset,
128 .synth_in = spk_ttyio_in,
129 .synth_in_nowait = spk_ttyio_in_nowait,
130 .flush_buffer = spk_ttyio_flush_buffer,
131 .wait_for_xmitr = spk_ttyio_wait_for_xmitr,
132 };
133 EXPORT_SYMBOL_GPL(spk_ttyio_ops);
134
get_termios(struct tty_struct * tty,struct ktermios * out_termios)135 static inline void get_termios(struct tty_struct *tty,
136 struct ktermios *out_termios)
137 {
138 down_read(&tty->termios_rwsem);
139 *out_termios = tty->termios;
140 up_read(&tty->termios_rwsem);
141 }
142
spk_ttyio_initialise_ldisc(struct spk_synth * synth)143 static int spk_ttyio_initialise_ldisc(struct spk_synth *synth)
144 {
145 int ret = 0;
146 struct tty_struct *tty;
147 struct ktermios tmp_termios;
148 dev_t dev;
149
150 ret = get_dev_to_use(synth, &dev);
151 if (ret)
152 return ret;
153
154 tty = tty_kopen_exclusive(dev);
155 if (IS_ERR(tty))
156 return PTR_ERR(tty);
157
158 if (tty->ops->open)
159 ret = tty->ops->open(tty, NULL);
160 else
161 ret = -ENODEV;
162
163 if (ret) {
164 tty_unlock(tty);
165 return ret;
166 }
167
168 clear_bit(TTY_HUPPED, &tty->flags);
169 /* ensure hardware flow control is enabled */
170 get_termios(tty, &tmp_termios);
171 if (!(tmp_termios.c_cflag & CRTSCTS)) {
172 tmp_termios.c_cflag |= CRTSCTS;
173 tty_set_termios(tty, &tmp_termios);
174 /*
175 * check c_cflag to see if it's updated as tty_set_termios
176 * may not return error even when no tty bits are
177 * changed by the request.
178 */
179 get_termios(tty, &tmp_termios);
180 if (!(tmp_termios.c_cflag & CRTSCTS))
181 pr_warn("speakup: Failed to set hardware flow control\n");
182 }
183
184 tty_unlock(tty);
185
186 mutex_lock(&speakup_tty_mutex);
187 speakup_tty = tty;
188 ret = tty_set_ldisc(tty, N_SPEAKUP);
189 speakup_tty = NULL;
190 mutex_unlock(&speakup_tty_mutex);
191
192 if (!ret) {
193 /* Success */
194 struct spk_ldisc_data *ldisc_data = tty->disc_data;
195
196 ldisc_data->synth = synth;
197 synth->dev = tty;
198 return 0;
199 }
200
201 pr_err("speakup: Failed to set N_SPEAKUP on tty\n");
202
203 tty_lock(tty);
204 if (tty->ops->close)
205 tty->ops->close(tty, NULL);
206 tty_unlock(tty);
207
208 tty_kclose(tty);
209
210 return ret;
211 }
212
spk_ttyio_register_ldisc(void)213 void spk_ttyio_register_ldisc(void)
214 {
215 if (tty_register_ldisc(&spk_ttyio_ldisc_ops))
216 pr_warn("speakup: Error registering line discipline. Most synths won't work.\n");
217 }
218
spk_ttyio_unregister_ldisc(void)219 void spk_ttyio_unregister_ldisc(void)
220 {
221 tty_unregister_ldisc(&spk_ttyio_ldisc_ops);
222 }
223
spk_ttyio_out(struct spk_synth * in_synth,const char ch)224 static int spk_ttyio_out(struct spk_synth *in_synth, const char ch)
225 {
226 struct tty_struct *tty = in_synth->dev;
227 int ret;
228
229 if (!in_synth->alive || !tty->ops->write)
230 return 0;
231
232 ret = tty->ops->write(tty, &ch, 1);
233
234 if (ret == 0)
235 /* No room */
236 return 0;
237
238 if (ret > 0)
239 /* Success */
240 return 1;
241
242 pr_warn("%s: I/O error, deactivating speakup\n",
243 in_synth->long_name);
244 /* No synth any more, so nobody will restart TTYs,
245 * and we thus need to do it ourselves. Now that there
246 * is no synth we can let application flood anyway
247 */
248 in_synth->alive = 0;
249 speakup_start_ttys();
250 return 0;
251 }
252
spk_ttyio_out_unicode(struct spk_synth * in_synth,u16 ch)253 static int spk_ttyio_out_unicode(struct spk_synth *in_synth, u16 ch)
254 {
255 int ret;
256
257 if (ch < 0x80) {
258 ret = spk_ttyio_out(in_synth, ch);
259 } else if (ch < 0x800) {
260 ret = spk_ttyio_out(in_synth, 0xc0 | (ch >> 6));
261 ret &= spk_ttyio_out(in_synth, 0x80 | (ch & 0x3f));
262 } else {
263 ret = spk_ttyio_out(in_synth, 0xe0 | (ch >> 12));
264 ret &= spk_ttyio_out(in_synth, 0x80 | ((ch >> 6) & 0x3f));
265 ret &= spk_ttyio_out(in_synth, 0x80 | (ch & 0x3f));
266 }
267 return ret;
268 }
269
spk_ttyio_send_xchar(struct spk_synth * in_synth,char ch)270 static void spk_ttyio_send_xchar(struct spk_synth *in_synth, char ch)
271 {
272 struct tty_struct *tty = in_synth->dev;
273
274 if (tty->ops->send_xchar)
275 tty->ops->send_xchar(tty, ch);
276 }
277
spk_ttyio_tiocmset(struct spk_synth * in_synth,unsigned int set,unsigned int clear)278 static void spk_ttyio_tiocmset(struct spk_synth *in_synth, unsigned int set, unsigned int clear)
279 {
280 struct tty_struct *tty = in_synth->dev;
281
282 if (tty->ops->tiocmset)
283 tty->ops->tiocmset(tty, set, clear);
284 }
285
spk_ttyio_wait_for_xmitr(struct spk_synth * in_synth)286 static int spk_ttyio_wait_for_xmitr(struct spk_synth *in_synth)
287 {
288 return 1;
289 }
290
ttyio_in(struct spk_synth * in_synth,int timeout)291 static unsigned char ttyio_in(struct spk_synth *in_synth, int timeout)
292 {
293 struct tty_struct *tty = in_synth->dev;
294 struct spk_ldisc_data *ldisc_data = tty->disc_data;
295 char rv;
296
297 if (!timeout) {
298 if (!try_wait_for_completion(&ldisc_data->completion))
299 return 0xff;
300 } else if (wait_for_completion_timeout(&ldisc_data->completion,
301 usecs_to_jiffies(timeout)) == 0) {
302 pr_warn("spk_ttyio: timeout (%d) while waiting for input\n",
303 timeout);
304 return 0xff;
305 }
306
307 rv = ldisc_data->buf;
308 /* Make sure we have read buf before we set buf_free to let
309 * the producer overwrite it
310 */
311 mb();
312 ldisc_data->buf_free = true;
313 /* Let TTY push more characters */
314 tty_flip_buffer_push(tty->port);
315
316 return rv;
317 }
318
spk_ttyio_in(struct spk_synth * in_synth)319 static unsigned char spk_ttyio_in(struct spk_synth *in_synth)
320 {
321 return ttyio_in(in_synth, SPK_SYNTH_TIMEOUT);
322 }
323
spk_ttyio_in_nowait(struct spk_synth * in_synth)324 static unsigned char spk_ttyio_in_nowait(struct spk_synth *in_synth)
325 {
326 u8 rv = ttyio_in(in_synth, 0);
327
328 return (rv == 0xff) ? 0 : rv;
329 }
330
spk_ttyio_flush_buffer(struct spk_synth * in_synth)331 static void spk_ttyio_flush_buffer(struct spk_synth *in_synth)
332 {
333 struct tty_struct *tty = in_synth->dev;
334
335 if (tty->ops->flush_buffer)
336 tty->ops->flush_buffer(tty);
337 }
338
spk_ttyio_synth_probe(struct spk_synth * synth)339 int spk_ttyio_synth_probe(struct spk_synth *synth)
340 {
341 int rv = spk_ttyio_initialise_ldisc(synth);
342
343 if (rv)
344 return rv;
345
346 synth->alive = 1;
347
348 return 0;
349 }
350 EXPORT_SYMBOL_GPL(spk_ttyio_synth_probe);
351
spk_ttyio_release(struct spk_synth * in_synth)352 void spk_ttyio_release(struct spk_synth *in_synth)
353 {
354 struct tty_struct *tty = in_synth->dev;
355
356 if (tty == NULL)
357 return;
358
359 tty_lock(tty);
360
361 if (tty->ops->close)
362 tty->ops->close(tty, NULL);
363
364 tty_ldisc_flush(tty);
365 tty_unlock(tty);
366 tty_kclose(tty);
367
368 in_synth->dev = NULL;
369 }
370 EXPORT_SYMBOL_GPL(spk_ttyio_release);
371
spk_ttyio_synth_immediate(struct spk_synth * in_synth,const char * buff)372 const char *spk_ttyio_synth_immediate(struct spk_synth *in_synth, const char *buff)
373 {
374 struct tty_struct *tty = in_synth->dev;
375 u_char ch;
376
377 while ((ch = *buff)) {
378 if (ch == '\n')
379 ch = in_synth->procspeech;
380 if (tty_write_room(tty) < 1 ||
381 !in_synth->io_ops->synth_out(in_synth, ch))
382 return buff;
383 buff++;
384 }
385 return NULL;
386 }
387 EXPORT_SYMBOL_GPL(spk_ttyio_synth_immediate);
388