summaryrefslogtreecommitdiff
path: root/drivers/tty/hvc/hvsi_lib.c
blob: 347050ea414a7f37e3962869f29437129cea1c75 (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
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
#include <linux/types.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/console.h>
#include <asm/hvsi.h>

#include "hvc_console.h"

static int hvsi_send_packet(struct hvsi_priv *pv, struct hvsi_header *packet)
{
	packet->seqno = cpu_to_be16(atomic_inc_return(&pv->seqno));

	/* Assumes that always succeeds, works in practice */
	return pv->put_chars(pv->termno, (char *)packet, packet->len);
}

static void hvsi_start_handshake(struct hvsi_priv *pv)
{
	struct hvsi_query q;

	/* Reset state */
	pv->established = 0;
	atomic_set(&pv->seqno, 0);

	pr_devel("HVSI@%x: Handshaking started\n", pv->termno);

	/* Send version query */
	q.hdr.type = VS_QUERY_PACKET_HEADER;
	q.hdr.len = sizeof(struct hvsi_query);
	q.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
	hvsi_send_packet(pv, &q.hdr);
}

static int hvsi_send_close(struct hvsi_priv *pv)
{
	struct hvsi_control ctrl;

	pv->established = 0;

	ctrl.hdr.type = VS_CONTROL_PACKET_HEADER;
	ctrl.hdr.len = sizeof(struct hvsi_control);
	ctrl.verb = cpu_to_be16(VSV_CLOSE_PROTOCOL);
	return hvsi_send_packet(pv, &ctrl.hdr);
}

static void hvsi_cd_change(struct hvsi_priv *pv, int cd)
{
	if (cd)
		pv->mctrl |= TIOCM_CD;
	else {
		pv->mctrl &= ~TIOCM_CD;

		/* We copy the existing hvsi driver semantics
		 * here which are to trigger a hangup when
		 * we get a carrier loss.
		 * Closing our connection to the server will
		 * do just that.
		 */
		if (!pv->is_console && pv->opened) {
			pr_devel("HVSI@%x Carrier lost, hanging up !\n",
				 pv->termno);
			hvsi_send_close(pv);
		}
	}
}

static void hvsi_got_control(struct hvsi_priv *pv)
{
	struct hvsi_control *pkt = (struct hvsi_control *)pv->inbuf;

	switch (be16_to_cpu(pkt->verb)) {
	case VSV_CLOSE_PROTOCOL:
		/* We restart the handshaking */
		hvsi_start_handshake(pv);
		break;
	case VSV_MODEM_CTL_UPDATE:
		/* Transition of carrier detect */
		hvsi_cd_change(pv, be32_to_cpu(pkt->word) & HVSI_TSCD);
		break;
	}
}

static void hvsi_got_query(struct hvsi_priv *pv)
{
	struct hvsi_query *pkt = (struct hvsi_query *)pv->inbuf;
	struct hvsi_query_response r;

	/* We only handle version queries */
	if (be16_to_cpu(pkt->verb) != VSV_SEND_VERSION_NUMBER)
		return;

	pr_devel("HVSI@%x: Got version query, sending response...\n",
		 pv->termno);

	/* Send version response */
	r.hdr.type = VS_QUERY_RESPONSE_PACKET_HEADER;
	r.hdr.len = sizeof(struct hvsi_query_response);
	r.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
	r.u.version = HVSI_VERSION;
	r.query_seqno = pkt->hdr.seqno;
	hvsi_send_packet(pv, &r.hdr);

	/* Assume protocol is open now */
	pv->established = 1;
}

static void hvsi_got_response(struct hvsi_priv *pv)
{
	struct hvsi_query_response *r =
		(struct hvsi_query_response *)pv->inbuf;

	switch(r->verb) {
	case VSV_SEND_MODEM_CTL_STATUS:
		hvsi_cd_change(pv, be32_to_cpu(r->u.mctrl_word) & HVSI_TSCD);
		pv->mctrl_update = 1;
		break;
	}
}

static int hvsi_check_packet(struct hvsi_priv *pv)
{
	u8 len, type;

	/* Check header validity. If it's invalid, we ditch
	 * the whole buffer and hope we eventually resync
	 */
	if (pv->inbuf[0] < 0xfc) {
		pv->inbuf_len = pv->inbuf_pktlen = 0;
		return 0;
	}
	type = pv->inbuf[0];
	len = pv->inbuf[1];

	/* Packet incomplete ? */
	if (pv->inbuf_len < len)
		return 0;

	pr_devel("HVSI@%x: Got packet type %x len %d bytes:\n",
		 pv->termno, type, len);

	/* We have a packet, yay ! Handle it */
	switch(type) {
	case VS_DATA_PACKET_HEADER:
		pv->inbuf_pktlen = len - 4;
		pv->inbuf_cur = 4;
		return 1;
	case VS_CONTROL_PACKET_HEADER:
		hvsi_got_control(pv);
		break;
	case VS_QUERY_PACKET_HEADER:
		hvsi_got_query(pv);
		break;
	case VS_QUERY_RESPONSE_PACKET_HEADER:
		hvsi_got_response(pv);
		break;
	}

	/* Swallow packet and retry */
	pv->inbuf_len -= len;
	memmove(pv->inbuf, &pv->inbuf[len], pv->inbuf_len);
	return 1;
}

static int hvsi_get_packet(struct hvsi_priv *pv)
{
	/* If we have room in the buffer, ask HV for more */
	if (pv->inbuf_len < HVSI_INBUF_SIZE)
		pv->inbuf_len += pv->get_chars(pv->termno,
					     &pv->inbuf[pv->inbuf_len],
					     HVSI_INBUF_SIZE - pv->inbuf_len);
	/*
	 * If we have at least 4 bytes in the buffer, check for
	 * a full packet and retry
	 */
	if (pv->inbuf_len >= 4)
		return hvsi_check_packet(pv);
	return 0;
}

int hvsilib_get_chars(struct hvsi_priv *pv, char *buf, int count)
{
	unsigned int tries, read = 0;

	if (WARN_ON(!pv))
		return -ENXIO;

	/* If we aren't open, don't do anything in order to avoid races
	 * with connection establishment. The hvc core will call this
	 * before we have returned from notifier_add(), and we need to
	 * avoid multiple users playing with the receive buffer
	 */
	if (!pv->opened)
		return 0;

	/* We try twice, once with what data we have and once more
	 * after we try to fetch some more from the hypervisor
	 */
	for (tries = 1; count && tries < 2; tries++) {
		/* Consume existing data packet */
		if (pv->inbuf_pktlen) {
			unsigned int l = min(count, (int)pv->inbuf_pktlen);
			memcpy(&buf[read], &pv->inbuf[pv->inbuf_cur], l);
			pv->inbuf_cur += l;
			pv->inbuf_pktlen -= l;
			count -= l;
			read += l;
		}
		if (count == 0)
			break;

		/* Data packet fully consumed, move down remaning data */
		if (pv->inbuf_cur) {
			pv->inbuf_len -= pv->inbuf_cur;
			memmove(pv->inbuf, &pv->inbuf[pv->inbuf_cur],
				pv->inbuf_len);
			pv->inbuf_cur = 0;
		}

		/* Try to get another packet */
		if (hvsi_get_packet(pv))
			tries--;
	}
	if (!pv->established) {
		pr_devel("HVSI@%x: returning -EPIPE\n", pv->termno);
		return -EPIPE;
	}
	return read;
}

int hvsilib_put_chars(struct hvsi_priv *pv, const char *buf, int count)
{
	struct hvsi_data dp;
	int rc, adjcount = min(count, HVSI_MAX_OUTGOING_DATA);

	if (WARN_ON(!pv))
		return -ENODEV;

	dp.hdr.type = VS_DATA_PACKET_HEADER;
	dp.hdr.len = adjcount + sizeof(struct hvsi_header);
	memcpy(dp.data, buf, adjcount);
	rc = hvsi_send_packet(pv, &dp.hdr);
	if (rc <= 0)
		return rc;
	return adjcount;
}

static void maybe_msleep(unsigned long ms)
{
	/* During early boot, IRQs are disabled, use mdelay */
	if (irqs_disabled())
		mdelay(ms);
	else
		msleep(ms);
}

int hvsilib_read_mctrl(struct hvsi_priv *pv)
{
	struct hvsi_query q;
	int rc, timeout;

	pr_devel("HVSI@%x: Querying modem control status...\n",
		 pv->termno);

	pv->mctrl_update = 0;
	q.hdr.type = VS_QUERY_PACKET_HEADER;
	q.hdr.len = sizeof(struct hvsi_query);
	q.verb = cpu_to_be16(VSV_SEND_MODEM_CTL_STATUS);
	rc = hvsi_send_packet(pv, &q.hdr);
	if (rc <= 0) {
		pr_devel("HVSI@%x: Error %d...\n", pv->termno, rc);
		return rc;
	}

	/* Try for up to 200ms */
	for (timeout = 0; timeout < 20; timeout++) {
		if (!pv->established)
			return -ENXIO;
		if (pv->mctrl_update)
			return 0;
		if (!hvsi_get_packet(pv))
			maybe_msleep(10);
	}
	return -EIO;
}

int hvsilib_write_mctrl(struct hvsi_priv *pv, int dtr)
{
	struct hvsi_control ctrl;
	unsigned short mctrl;

	mctrl = pv->mctrl;
	if (dtr)
		mctrl |= TIOCM_DTR;
	else
		mctrl &= ~TIOCM_DTR;
	if (mctrl == pv->mctrl)
		return 0;
	pv->mctrl = mctrl;

	pr_devel("HVSI@%x: %s DTR...\n", pv->termno,
		 dtr ? "Setting" : "Clearing");

	ctrl.hdr.type = VS_CONTROL_PACKET_HEADER,
	ctrl.hdr.len = sizeof(struct hvsi_control);
	ctrl.verb = cpu_to_be16(VSV_SET_MODEM_CTL);
	ctrl.mask = cpu_to_be32(HVSI_TSDTR);
	ctrl.word = cpu_to_be32(dtr ? HVSI_TSDTR : 0);
	return hvsi_send_packet(pv, &ctrl.hdr);
}

void hvsilib_establish(struct hvsi_priv *pv)
{
	int timeout;

	pr_devel("HVSI@%x: Establishing...\n", pv->termno);

	/* Try for up to 200ms, there can be a packet to
	 * start the process waiting for us...
	 */
	for (timeout = 0; timeout < 20; timeout++) {
		if (pv->established)
			goto established;
		if (!hvsi_get_packet(pv))
			maybe_msleep(10);
	}

	/* Failed, send a close connection packet just
	 * in case
	 */
	pr_devel("HVSI@%x:   ... sending close\n", pv->termno);

	hvsi_send_close(pv);

	/* Then restart handshake */

	pr_devel("HVSI@%x:   ... restarting handshake\n", pv->termno);

	hvsi_start_handshake(pv);

	pr_devel("HVSI@%x:   ... waiting handshake\n", pv->termno);

	/* Try for up to 400ms */
	for (timeout = 0; timeout < 40; timeout++) {
		if (pv->established)
			goto established;
		if (!hvsi_get_packet(pv))
			maybe_msleep(10);
	}

	if (!pv->established) {
		pr_devel("HVSI@%x: Timeout handshaking, giving up !\n",
			 pv->termno);
		return;
	}
 established:
	/* Query modem control lines */

	pr_devel("HVSI@%x:   ... established, reading mctrl\n", pv->termno);

	hvsilib_read_mctrl(pv);

	/* Set our own DTR */

	pr_devel("HVSI@%x:   ... setting mctrl\n", pv->termno);

	hvsilib_write_mctrl(pv, 1);

	/* Set the opened flag so reads are allowed */
	wmb();
	pv->opened = 1;
}

int hvsilib_open(struct hvsi_priv *pv, struct hvc_struct *hp)
{
	pr_devel("HVSI@%x: open !\n", pv->termno);

	/* Keep track of the tty data structure */
	pv->tty = tty_port_tty_get(&hp->port);

	hvsilib_establish(pv);

	return 0;
}

void hvsilib_close(struct hvsi_priv *pv, struct hvc_struct *hp)
{
	unsigned long flags;

	pr_devel("HVSI@%x: close !\n", pv->termno);

	if (!pv->is_console) {
		pr_devel("HVSI@%x: Not a console, tearing down\n",
			 pv->termno);

		/* Clear opened, synchronize with khvcd */
		spin_lock_irqsave(&hp->lock, flags);
		pv->opened = 0;
		spin_unlock_irqrestore(&hp->lock, flags);

		/* Clear our own DTR */
		if (!pv->tty || (pv->tty->termios.c_cflag & HUPCL))
			hvsilib_write_mctrl(pv, 0);

		/* Tear down the connection */
		hvsi_send_close(pv);
	}

	if (pv->tty)
		tty_kref_put(pv->tty);
	pv->tty = NULL;
}

void hvsilib_init(struct hvsi_priv *pv,
		  int (*get_chars)(uint32_t termno, char *buf, int count),
		  int (*put_chars)(uint32_t termno, const char *buf,
				   int count),
		  int termno, int is_console)
{
	memset(pv, 0, sizeof(*pv));
	pv->get_chars = get_chars;
	pv->put_chars = put_chars;
	pv->termno = termno;
	pv->is_console = is_console;
}