summaryrefslogtreecommitdiff
path: root/drivers/accessibility/speakup/spk_ttyio.c
blob: 2e39fcf492d8bd8d1b0e09a5887714ba38645b15 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
// SPDX-License-Identifier: GPL-2.0
#include <linux/types.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/slab.h>

#include "speakup.h"
#include "spk_types.h"
#include "spk_priv.h"

struct spk_ldisc_data {
	char buf;
	struct completion completion;
	bool buf_free;
	struct spk_synth *synth;
};

/*
 * This allows to catch within spk_ttyio_ldisc_open whether it is getting set
 * on for a speakup-driven device.
 */
static struct tty_struct *speakup_tty;
/* This mutex serializes the use of such global speakup_tty variable */
static DEFINE_MUTEX(speakup_tty_mutex);

static int ser_to_dev(int ser, dev_t *dev_no)
{
	if (ser < 0 || ser > (255 - 64)) {
		pr_err("speakup: Invalid ser param. Must be between 0 and 191 inclusive.\n");
		return -EINVAL;
	}

	*dev_no = MKDEV(4, (64 + ser));
	return 0;
}

static int get_dev_to_use(struct spk_synth *synth, dev_t *dev_no)
{
	/* use ser only when dev is not specified */
	if (strcmp(synth->dev_name, SYNTH_DEFAULT_DEV) ||
	    synth->ser == SYNTH_DEFAULT_SER)
		return tty_dev_name_to_number(synth->dev_name, dev_no);

	return ser_to_dev(synth->ser, dev_no);
}

static int spk_ttyio_ldisc_open(struct tty_struct *tty)
{
	struct spk_ldisc_data *ldisc_data;

	if (tty != speakup_tty)
		/* Somebody tried to use this line discipline outside speakup */
		return -ENODEV;

	if (!tty->ops->write)
		return -EOPNOTSUPP;

	ldisc_data = kmalloc(sizeof(*ldisc_data), GFP_KERNEL);
	if (!ldisc_data)
		return -ENOMEM;

	init_completion(&ldisc_data->completion);
	ldisc_data->buf_free = true;
	tty->disc_data = ldisc_data;

	return 0;
}

static void spk_ttyio_ldisc_close(struct tty_struct *tty)
{
	kfree(tty->disc_data);
}

static int spk_ttyio_receive_buf2(struct tty_struct *tty,
				  const unsigned char *cp, char *fp, int count)
{
	struct spk_ldisc_data *ldisc_data = tty->disc_data;
	struct spk_synth *synth = ldisc_data->synth;

	if (synth->read_buff_add) {
		int i;

		for (i = 0; i < count; i++)
			synth->read_buff_add(cp[i]);

		return count;
	}

	if (!ldisc_data->buf_free)
		/* ttyio_in will tty_schedule_flip */
		return 0;

	/* Make sure the consumer has read buf before we have seen
	 * buf_free == true and overwrite buf
	 */
	mb();

	ldisc_data->buf = cp[0];
	ldisc_data->buf_free = false;
	complete(&ldisc_data->completion);

	return 1;
}

static struct tty_ldisc_ops spk_ttyio_ldisc_ops = {
	.owner          = THIS_MODULE,
	.name           = "speakup_ldisc",
	.open           = spk_ttyio_ldisc_open,
	.close          = spk_ttyio_ldisc_close,
	.receive_buf2	= spk_ttyio_receive_buf2,
};

static int spk_ttyio_out(struct spk_synth *in_synth, const char ch);
static int spk_ttyio_out_unicode(struct spk_synth *in_synth, u16 ch);
static void spk_ttyio_send_xchar(struct spk_synth *in_synth, char ch);
static void spk_ttyio_tiocmset(struct spk_synth *in_synth, unsigned int set, unsigned int clear);
static unsigned char spk_ttyio_in(struct spk_synth *in_synth);
static unsigned char spk_ttyio_in_nowait(struct spk_synth *in_synth);
static void spk_ttyio_flush_buffer(struct spk_synth *in_synth);
static int spk_ttyio_wait_for_xmitr(struct spk_synth *in_synth);

struct spk_io_ops spk_ttyio_ops = {
	.synth_out = spk_ttyio_out,
	.synth_out_unicode = spk_ttyio_out_unicode,
	.send_xchar = spk_ttyio_send_xchar,
	.tiocmset = spk_ttyio_tiocmset,
	.synth_in = spk_ttyio_in,
	.synth_in_nowait = spk_ttyio_in_nowait,
	.flush_buffer = spk_ttyio_flush_buffer,
	.wait_for_xmitr = spk_ttyio_wait_for_xmitr,
};
EXPORT_SYMBOL_GPL(spk_ttyio_ops);

static inline void get_termios(struct tty_struct *tty,
			       struct ktermios *out_termios)
{
	down_read(&tty->termios_rwsem);
	*out_termios = tty->termios;
	up_read(&tty->termios_rwsem);
}

static int spk_ttyio_initialise_ldisc(struct spk_synth *synth)
{
	int ret = 0;
	struct tty_struct *tty;
	struct ktermios tmp_termios;
	dev_t dev;

	ret = get_dev_to_use(synth, &dev);
	if (ret)
		return ret;

	tty = tty_kopen_exclusive(dev);
	if (IS_ERR(tty))
		return PTR_ERR(tty);

	if (tty->ops->open)
		ret = tty->ops->open(tty, NULL);
	else
		ret = -ENODEV;

	if (ret) {
		tty_unlock(tty);
		return ret;
	}

	clear_bit(TTY_HUPPED, &tty->flags);
	/* ensure hardware flow control is enabled */
	get_termios(tty, &tmp_termios);
	if (!(tmp_termios.c_cflag & CRTSCTS)) {
		tmp_termios.c_cflag |= CRTSCTS;
		tty_set_termios(tty, &tmp_termios);
		/*
		 * check c_cflag to see if it's updated as tty_set_termios
		 * may not return error even when no tty bits are
		 * changed by the request.
		 */
		get_termios(tty, &tmp_termios);
		if (!(tmp_termios.c_cflag & CRTSCTS))
			pr_warn("speakup: Failed to set hardware flow control\n");
	}

	tty_unlock(tty);

	mutex_lock(&speakup_tty_mutex);
	speakup_tty = tty;
	ret = tty_set_ldisc(tty, N_SPEAKUP);
	speakup_tty = NULL;
	mutex_unlock(&speakup_tty_mutex);

	if (!ret) {
		/* Success */
		struct spk_ldisc_data *ldisc_data = tty->disc_data;

		ldisc_data->synth = synth;
		synth->dev = tty;
		return 0;
	}

	pr_err("speakup: Failed to set N_SPEAKUP on tty\n");

	tty_lock(tty);
	if (tty->ops->close)
		tty->ops->close(tty, NULL);
	tty_unlock(tty);

	tty_kclose(tty);

	return ret;
}

void spk_ttyio_register_ldisc(void)
{
	if (tty_register_ldisc(N_SPEAKUP, &spk_ttyio_ldisc_ops))
		pr_warn("speakup: Error registering line discipline. Most synths won't work.\n");
}

void spk_ttyio_unregister_ldisc(void)
{
	if (tty_unregister_ldisc(N_SPEAKUP))
		pr_warn("speakup: Couldn't unregister ldisc\n");
}

static int spk_ttyio_out(struct spk_synth *in_synth, const char ch)
{
	struct tty_struct *tty = in_synth->dev;
	int ret;

	if (!in_synth->alive || !tty->ops->write)
		return 0;

	ret = tty->ops->write(tty, &ch, 1);

	if (ret == 0)
		/* No room */
		return 0;

	if (ret > 0)
		/* Success */
		return 1;

	pr_warn("%s: I/O error, deactivating speakup\n",
		in_synth->long_name);
	/* No synth any more, so nobody will restart TTYs,
	 * and we thus need to do it ourselves.  Now that there
	 * is no synth we can let application flood anyway
	 */
	in_synth->alive = 0;
	speakup_start_ttys();
	return 0;
}

static int spk_ttyio_out_unicode(struct spk_synth *in_synth, u16 ch)
{
	int ret;

	if (ch < 0x80) {
		ret = spk_ttyio_out(in_synth, ch);
	} else if (ch < 0x800) {
		ret  = spk_ttyio_out(in_synth, 0xc0 | (ch >> 6));
		ret &= spk_ttyio_out(in_synth, 0x80 | (ch & 0x3f));
	} else {
		ret  = spk_ttyio_out(in_synth, 0xe0 | (ch >> 12));
		ret &= spk_ttyio_out(in_synth, 0x80 | ((ch >> 6) & 0x3f));
		ret &= spk_ttyio_out(in_synth, 0x80 | (ch & 0x3f));
	}
	return ret;
}

static void spk_ttyio_send_xchar(struct spk_synth *in_synth, char ch)
{
	struct tty_struct *tty = in_synth->dev;

	if (tty->ops->send_xchar)
		tty->ops->send_xchar(tty, ch);
}

static void spk_ttyio_tiocmset(struct spk_synth *in_synth, unsigned int set, unsigned int clear)
{
	struct tty_struct *tty = in_synth->dev;

	if (tty->ops->tiocmset)
		tty->ops->tiocmset(tty, set, clear);
}

static int spk_ttyio_wait_for_xmitr(struct spk_synth *in_synth)
{
	return 1;
}

static unsigned char ttyio_in(struct spk_synth *in_synth, int timeout)
{
	struct tty_struct *tty = in_synth->dev;
	struct spk_ldisc_data *ldisc_data = tty->disc_data;
	char rv;

	if (!timeout) {
		if (!try_wait_for_completion(&ldisc_data->completion))
			return 0xff;
	} else if (wait_for_completion_timeout(&ldisc_data->completion,
					usecs_to_jiffies(timeout)) == 0) {
		pr_warn("spk_ttyio: timeout (%d)  while waiting for input\n",
			timeout);
		return 0xff;
	}

	rv = ldisc_data->buf;
	/* Make sure we have read buf before we set buf_free to let
	 * the producer overwrite it
	 */
	mb();
	ldisc_data->buf_free = true;
	/* Let TTY push more characters */
	tty_schedule_flip(tty->port);

	return rv;
}

static unsigned char spk_ttyio_in(struct spk_synth *in_synth)
{
	return ttyio_in(in_synth, SPK_SYNTH_TIMEOUT);
}

static unsigned char spk_ttyio_in_nowait(struct spk_synth *in_synth)
{
	u8 rv = ttyio_in(in_synth, 0);

	return (rv == 0xff) ? 0 : rv;
}

static void spk_ttyio_flush_buffer(struct spk_synth *in_synth)
{
	struct tty_struct *tty = in_synth->dev;

	if (tty->ops->flush_buffer)
		tty->ops->flush_buffer(tty);
}

int spk_ttyio_synth_probe(struct spk_synth *synth)
{
	int rv = spk_ttyio_initialise_ldisc(synth);

	if (rv)
		return rv;

	synth->alive = 1;

	return 0;
}
EXPORT_SYMBOL_GPL(spk_ttyio_synth_probe);

void spk_ttyio_release(struct spk_synth *in_synth)
{
	struct tty_struct *tty = in_synth->dev;

	tty_lock(tty);

	if (tty->ops->close)
		tty->ops->close(tty, NULL);

	tty_ldisc_flush(tty);
	tty_unlock(tty);
	tty_kclose(tty);

	in_synth->dev = NULL;
}
EXPORT_SYMBOL_GPL(spk_ttyio_release);

const char *spk_ttyio_synth_immediate(struct spk_synth *in_synth, const char *buff)
{
	struct tty_struct *tty = in_synth->dev;
	u_char ch;

	while ((ch = *buff)) {
		if (ch == '\n')
			ch = in_synth->procspeech;
		if (tty_write_room(tty) < 1 ||
		    !in_synth->io_ops->synth_out(in_synth, ch))
			return buff;
		buff++;
	}
	return NULL;
}
EXPORT_SYMBOL_GPL(spk_ttyio_synth_immediate);