1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/types.h>
3 #include <linux/delay.h>
4 #include <linux/slab.h>
5 #include <linux/console.h>
6 #include <asm/hvsi.h>
7
8 #include "hvc_console.h"
9
hvsi_send_packet(struct hvsi_priv * pv,struct hvsi_header * packet)10 static int hvsi_send_packet(struct hvsi_priv *pv, struct hvsi_header *packet)
11 {
12 packet->seqno = cpu_to_be16(atomic_inc_return(&pv->seqno));
13
14 /* Assumes that always succeeds, works in practice */
15 return pv->put_chars(pv->termno, (char *)packet, packet->len);
16 }
17
hvsi_start_handshake(struct hvsi_priv * pv)18 static void hvsi_start_handshake(struct hvsi_priv *pv)
19 {
20 struct hvsi_query q;
21
22 /* Reset state */
23 pv->established = 0;
24 atomic_set(&pv->seqno, 0);
25
26 pr_devel("HVSI@%x: Handshaking started\n", pv->termno);
27
28 /* Send version query */
29 q.hdr.type = VS_QUERY_PACKET_HEADER;
30 q.hdr.len = sizeof(struct hvsi_query);
31 q.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
32 hvsi_send_packet(pv, &q.hdr);
33 }
34
hvsi_send_close(struct hvsi_priv * pv)35 static int hvsi_send_close(struct hvsi_priv *pv)
36 {
37 struct hvsi_control ctrl;
38
39 pv->established = 0;
40
41 ctrl.hdr.type = VS_CONTROL_PACKET_HEADER;
42 ctrl.hdr.len = sizeof(struct hvsi_control);
43 ctrl.verb = cpu_to_be16(VSV_CLOSE_PROTOCOL);
44 return hvsi_send_packet(pv, &ctrl.hdr);
45 }
46
hvsi_cd_change(struct hvsi_priv * pv,int cd)47 static void hvsi_cd_change(struct hvsi_priv *pv, int cd)
48 {
49 if (cd)
50 pv->mctrl |= TIOCM_CD;
51 else {
52 pv->mctrl &= ~TIOCM_CD;
53
54 /* We copy the existing hvsi driver semantics
55 * here which are to trigger a hangup when
56 * we get a carrier loss.
57 * Closing our connection to the server will
58 * do just that.
59 */
60 if (!pv->is_console && pv->opened) {
61 pr_devel("HVSI@%x Carrier lost, hanging up !\n",
62 pv->termno);
63 hvsi_send_close(pv);
64 }
65 }
66 }
67
hvsi_got_control(struct hvsi_priv * pv)68 static void hvsi_got_control(struct hvsi_priv *pv)
69 {
70 struct hvsi_control *pkt = (struct hvsi_control *)pv->inbuf;
71
72 switch (be16_to_cpu(pkt->verb)) {
73 case VSV_CLOSE_PROTOCOL:
74 /* We restart the handshaking */
75 hvsi_start_handshake(pv);
76 break;
77 case VSV_MODEM_CTL_UPDATE:
78 /* Transition of carrier detect */
79 hvsi_cd_change(pv, be32_to_cpu(pkt->word) & HVSI_TSCD);
80 break;
81 }
82 }
83
hvsi_got_query(struct hvsi_priv * pv)84 static void hvsi_got_query(struct hvsi_priv *pv)
85 {
86 struct hvsi_query *pkt = (struct hvsi_query *)pv->inbuf;
87 struct hvsi_query_response r;
88
89 /* We only handle version queries */
90 if (be16_to_cpu(pkt->verb) != VSV_SEND_VERSION_NUMBER)
91 return;
92
93 pr_devel("HVSI@%x: Got version query, sending response...\n",
94 pv->termno);
95
96 /* Send version response */
97 r.hdr.type = VS_QUERY_RESPONSE_PACKET_HEADER;
98 r.hdr.len = sizeof(struct hvsi_query_response);
99 r.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
100 r.u.version = HVSI_VERSION;
101 r.query_seqno = pkt->hdr.seqno;
102 hvsi_send_packet(pv, &r.hdr);
103
104 /* Assume protocol is open now */
105 pv->established = 1;
106 }
107
hvsi_got_response(struct hvsi_priv * pv)108 static void hvsi_got_response(struct hvsi_priv *pv)
109 {
110 struct hvsi_query_response *r =
111 (struct hvsi_query_response *)pv->inbuf;
112
113 switch(r->verb) {
114 case VSV_SEND_MODEM_CTL_STATUS:
115 hvsi_cd_change(pv, be32_to_cpu(r->u.mctrl_word) & HVSI_TSCD);
116 pv->mctrl_update = 1;
117 break;
118 }
119 }
120
hvsi_check_packet(struct hvsi_priv * pv)121 static int hvsi_check_packet(struct hvsi_priv *pv)
122 {
123 u8 len, type;
124
125 /* Check header validity. If it's invalid, we ditch
126 * the whole buffer and hope we eventually resync
127 */
128 if (pv->inbuf[0] < 0xfc) {
129 pv->inbuf_len = pv->inbuf_pktlen = 0;
130 return 0;
131 }
132 type = pv->inbuf[0];
133 len = pv->inbuf[1];
134
135 /* Packet incomplete ? */
136 if (pv->inbuf_len < len)
137 return 0;
138
139 pr_devel("HVSI@%x: Got packet type %x len %d bytes:\n",
140 pv->termno, type, len);
141
142 /* We have a packet, yay ! Handle it */
143 switch(type) {
144 case VS_DATA_PACKET_HEADER:
145 pv->inbuf_pktlen = len - 4;
146 pv->inbuf_cur = 4;
147 return 1;
148 case VS_CONTROL_PACKET_HEADER:
149 hvsi_got_control(pv);
150 break;
151 case VS_QUERY_PACKET_HEADER:
152 hvsi_got_query(pv);
153 break;
154 case VS_QUERY_RESPONSE_PACKET_HEADER:
155 hvsi_got_response(pv);
156 break;
157 }
158
159 /* Swallow packet and retry */
160 pv->inbuf_len -= len;
161 memmove(pv->inbuf, &pv->inbuf[len], pv->inbuf_len);
162 return 1;
163 }
164
hvsi_get_packet(struct hvsi_priv * pv)165 static int hvsi_get_packet(struct hvsi_priv *pv)
166 {
167 /* If we have room in the buffer, ask HV for more */
168 if (pv->inbuf_len < HVSI_INBUF_SIZE)
169 pv->inbuf_len += pv->get_chars(pv->termno,
170 &pv->inbuf[pv->inbuf_len],
171 HVSI_INBUF_SIZE - pv->inbuf_len);
172 /*
173 * If we have at least 4 bytes in the buffer, check for
174 * a full packet and retry
175 */
176 if (pv->inbuf_len >= 4)
177 return hvsi_check_packet(pv);
178 return 0;
179 }
180
hvsilib_get_chars(struct hvsi_priv * pv,char * buf,int count)181 int hvsilib_get_chars(struct hvsi_priv *pv, char *buf, int count)
182 {
183 unsigned int tries, read = 0;
184
185 if (WARN_ON(!pv))
186 return -ENXIO;
187
188 /* If we aren't open, don't do anything in order to avoid races
189 * with connection establishment. The hvc core will call this
190 * before we have returned from notifier_add(), and we need to
191 * avoid multiple users playing with the receive buffer
192 */
193 if (!pv->opened)
194 return 0;
195
196 /* We try twice, once with what data we have and once more
197 * after we try to fetch some more from the hypervisor
198 */
199 for (tries = 1; count && tries < 2; tries++) {
200 /* Consume existing data packet */
201 if (pv->inbuf_pktlen) {
202 unsigned int l = min(count, (int)pv->inbuf_pktlen);
203 memcpy(&buf[read], &pv->inbuf[pv->inbuf_cur], l);
204 pv->inbuf_cur += l;
205 pv->inbuf_pktlen -= l;
206 count -= l;
207 read += l;
208 }
209 if (count == 0)
210 break;
211
212 /* Data packet fully consumed, move down remaning data */
213 if (pv->inbuf_cur) {
214 pv->inbuf_len -= pv->inbuf_cur;
215 memmove(pv->inbuf, &pv->inbuf[pv->inbuf_cur],
216 pv->inbuf_len);
217 pv->inbuf_cur = 0;
218 }
219
220 /* Try to get another packet */
221 if (hvsi_get_packet(pv))
222 tries--;
223 }
224 if (!pv->established) {
225 pr_devel("HVSI@%x: returning -EPIPE\n", pv->termno);
226 return -EPIPE;
227 }
228 return read;
229 }
230
hvsilib_put_chars(struct hvsi_priv * pv,const char * buf,int count)231 int hvsilib_put_chars(struct hvsi_priv *pv, const char *buf, int count)
232 {
233 struct hvsi_data dp;
234 int rc, adjcount = min(count, HVSI_MAX_OUTGOING_DATA);
235
236 if (WARN_ON(!pv))
237 return -ENODEV;
238
239 dp.hdr.type = VS_DATA_PACKET_HEADER;
240 dp.hdr.len = adjcount + sizeof(struct hvsi_header);
241 memcpy(dp.data, buf, adjcount);
242 rc = hvsi_send_packet(pv, &dp.hdr);
243 if (rc <= 0)
244 return rc;
245 return adjcount;
246 }
247
maybe_msleep(unsigned long ms)248 static void maybe_msleep(unsigned long ms)
249 {
250 /* During early boot, IRQs are disabled, use mdelay */
251 if (irqs_disabled())
252 mdelay(ms);
253 else
254 msleep(ms);
255 }
256
hvsilib_read_mctrl(struct hvsi_priv * pv)257 int hvsilib_read_mctrl(struct hvsi_priv *pv)
258 {
259 struct hvsi_query q;
260 int rc, timeout;
261
262 pr_devel("HVSI@%x: Querying modem control status...\n",
263 pv->termno);
264
265 pv->mctrl_update = 0;
266 q.hdr.type = VS_QUERY_PACKET_HEADER;
267 q.hdr.len = sizeof(struct hvsi_query);
268 q.verb = cpu_to_be16(VSV_SEND_MODEM_CTL_STATUS);
269 rc = hvsi_send_packet(pv, &q.hdr);
270 if (rc <= 0) {
271 pr_devel("HVSI@%x: Error %d...\n", pv->termno, rc);
272 return rc;
273 }
274
275 /* Try for up to 200ms */
276 for (timeout = 0; timeout < 20; timeout++) {
277 if (!pv->established)
278 return -ENXIO;
279 if (pv->mctrl_update)
280 return 0;
281 if (!hvsi_get_packet(pv))
282 maybe_msleep(10);
283 }
284 return -EIO;
285 }
286
hvsilib_write_mctrl(struct hvsi_priv * pv,int dtr)287 int hvsilib_write_mctrl(struct hvsi_priv *pv, int dtr)
288 {
289 struct hvsi_control ctrl;
290 unsigned short mctrl;
291
292 mctrl = pv->mctrl;
293 if (dtr)
294 mctrl |= TIOCM_DTR;
295 else
296 mctrl &= ~TIOCM_DTR;
297 if (mctrl == pv->mctrl)
298 return 0;
299 pv->mctrl = mctrl;
300
301 pr_devel("HVSI@%x: %s DTR...\n", pv->termno,
302 dtr ? "Setting" : "Clearing");
303
304 ctrl.hdr.type = VS_CONTROL_PACKET_HEADER,
305 ctrl.hdr.len = sizeof(struct hvsi_control);
306 ctrl.verb = cpu_to_be16(VSV_SET_MODEM_CTL);
307 ctrl.mask = cpu_to_be32(HVSI_TSDTR);
308 ctrl.word = cpu_to_be32(dtr ? HVSI_TSDTR : 0);
309 return hvsi_send_packet(pv, &ctrl.hdr);
310 }
311
hvsilib_establish(struct hvsi_priv * pv)312 void hvsilib_establish(struct hvsi_priv *pv)
313 {
314 int timeout;
315
316 pr_devel("HVSI@%x: Establishing...\n", pv->termno);
317
318 /* Try for up to 200ms, there can be a packet to
319 * start the process waiting for us...
320 */
321 for (timeout = 0; timeout < 20; timeout++) {
322 if (pv->established)
323 goto established;
324 if (!hvsi_get_packet(pv))
325 maybe_msleep(10);
326 }
327
328 /* Failed, send a close connection packet just
329 * in case
330 */
331 pr_devel("HVSI@%x: ... sending close\n", pv->termno);
332
333 hvsi_send_close(pv);
334
335 /* Then restart handshake */
336
337 pr_devel("HVSI@%x: ... restarting handshake\n", pv->termno);
338
339 hvsi_start_handshake(pv);
340
341 pr_devel("HVSI@%x: ... waiting handshake\n", pv->termno);
342
343 /* Try for up to 400ms */
344 for (timeout = 0; timeout < 40; timeout++) {
345 if (pv->established)
346 goto established;
347 if (!hvsi_get_packet(pv))
348 maybe_msleep(10);
349 }
350
351 if (!pv->established) {
352 pr_devel("HVSI@%x: Timeout handshaking, giving up !\n",
353 pv->termno);
354 return;
355 }
356 established:
357 /* Query modem control lines */
358
359 pr_devel("HVSI@%x: ... established, reading mctrl\n", pv->termno);
360
361 hvsilib_read_mctrl(pv);
362
363 /* Set our own DTR */
364
365 pr_devel("HVSI@%x: ... setting mctrl\n", pv->termno);
366
367 hvsilib_write_mctrl(pv, 1);
368
369 /* Set the opened flag so reads are allowed */
370 wmb();
371 pv->opened = 1;
372 }
373
hvsilib_open(struct hvsi_priv * pv,struct hvc_struct * hp)374 int hvsilib_open(struct hvsi_priv *pv, struct hvc_struct *hp)
375 {
376 pr_devel("HVSI@%x: open !\n", pv->termno);
377
378 /* Keep track of the tty data structure */
379 pv->tty = tty_port_tty_get(&hp->port);
380
381 hvsilib_establish(pv);
382
383 return 0;
384 }
385
hvsilib_close(struct hvsi_priv * pv,struct hvc_struct * hp)386 void hvsilib_close(struct hvsi_priv *pv, struct hvc_struct *hp)
387 {
388 unsigned long flags;
389
390 pr_devel("HVSI@%x: close !\n", pv->termno);
391
392 if (!pv->is_console) {
393 pr_devel("HVSI@%x: Not a console, tearing down\n",
394 pv->termno);
395
396 /* Clear opened, synchronize with khvcd */
397 spin_lock_irqsave(&hp->lock, flags);
398 pv->opened = 0;
399 spin_unlock_irqrestore(&hp->lock, flags);
400
401 /* Clear our own DTR */
402 if (!pv->tty || (pv->tty->termios.c_cflag & HUPCL))
403 hvsilib_write_mctrl(pv, 0);
404
405 /* Tear down the connection */
406 hvsi_send_close(pv);
407 }
408
409 tty_kref_put(pv->tty);
410 pv->tty = NULL;
411 }
412
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)413 void hvsilib_init(struct hvsi_priv *pv,
414 int (*get_chars)(uint32_t termno, char *buf, int count),
415 int (*put_chars)(uint32_t termno, const char *buf,
416 int count),
417 int termno, int is_console)
418 {
419 memset(pv, 0, sizeof(*pv));
420 pv->get_chars = get_chars;
421 pv->put_chars = put_chars;
422 pv->termno = termno;
423 pv->is_console = is_console;
424 }
425