serial: tegra: drop bogus NULL tty-port checks
[linux/fpc-iii.git] / drivers / tty / hvc / hvsi_lib.c
blob09289c8154aec41cb19b5bf6bf297ccdbb734547
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>
8 #include "hvc_console.h"
10 static int hvsi_send_packet(struct hvsi_priv *pv, struct hvsi_header *packet)
12 packet->seqno = cpu_to_be16(atomic_inc_return(&pv->seqno));
14 /* Assumes that always succeeds, works in practice */
15 return pv->put_chars(pv->termno, (char *)packet, packet->len);
18 static void hvsi_start_handshake(struct hvsi_priv *pv)
20 struct hvsi_query q;
22 /* Reset state */
23 pv->established = 0;
24 atomic_set(&pv->seqno, 0);
26 pr_devel("HVSI@%x: Handshaking started\n", pv->termno);
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);
35 static int hvsi_send_close(struct hvsi_priv *pv)
37 struct hvsi_control ctrl;
39 pv->established = 0;
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);
47 static void hvsi_cd_change(struct hvsi_priv *pv, int cd)
49 if (cd)
50 pv->mctrl |= TIOCM_CD;
51 else {
52 pv->mctrl &= ~TIOCM_CD;
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.
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);
68 static void hvsi_got_control(struct hvsi_priv *pv)
70 struct hvsi_control *pkt = (struct hvsi_control *)pv->inbuf;
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;
84 static void hvsi_got_query(struct hvsi_priv *pv)
86 struct hvsi_query *pkt = (struct hvsi_query *)pv->inbuf;
87 struct hvsi_query_response r;
89 /* We only handle version queries */
90 if (be16_to_cpu(pkt->verb) != VSV_SEND_VERSION_NUMBER)
91 return;
93 pr_devel("HVSI@%x: Got version query, sending response...\n",
94 pv->termno);
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);
104 /* Assume protocol is open now */
105 pv->established = 1;
108 static void hvsi_got_response(struct hvsi_priv *pv)
110 struct hvsi_query_response *r =
111 (struct hvsi_query_response *)pv->inbuf;
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;
121 static int hvsi_check_packet(struct hvsi_priv *pv)
123 u8 len, type;
125 /* Check header validity. If it's invalid, we ditch
126 * the whole buffer and hope we eventually resync
128 if (pv->inbuf[0] < 0xfc) {
129 pv->inbuf_len = pv->inbuf_pktlen = 0;
130 return 0;
132 type = pv->inbuf[0];
133 len = pv->inbuf[1];
135 /* Packet incomplete ? */
136 if (pv->inbuf_len < len)
137 return 0;
139 pr_devel("HVSI@%x: Got packet type %x len %d bytes:\n",
140 pv->termno, type, len);
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;
159 /* Swallow packet and retry */
160 pv->inbuf_len -= len;
161 memmove(pv->inbuf, &pv->inbuf[len], pv->inbuf_len);
162 return 1;
165 static int hvsi_get_packet(struct hvsi_priv *pv)
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);
173 * If we have at least 4 bytes in the buffer, check for
174 * a full packet and retry
176 if (pv->inbuf_len >= 4)
177 return hvsi_check_packet(pv);
178 return 0;
181 int hvsilib_get_chars(struct hvsi_priv *pv, char *buf, int count)
183 unsigned int tries, read = 0;
185 if (WARN_ON(!pv))
186 return -ENXIO;
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
193 if (!pv->opened)
194 return 0;
196 /* We try twice, once with what data we have and once more
197 * after we try to fetch some more from the hypervisor
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;
209 if (count == 0)
210 break;
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;
220 /* Try to get another packet */
221 if (hvsi_get_packet(pv))
222 tries--;
224 if (!pv->established) {
225 pr_devel("HVSI@%x: returning -EPIPE\n", pv->termno);
226 return -EPIPE;
228 return read;
231 int hvsilib_put_chars(struct hvsi_priv *pv, const char *buf, int count)
233 struct hvsi_data dp;
234 int rc, adjcount = min(count, HVSI_MAX_OUTGOING_DATA);
236 if (WARN_ON(!pv))
237 return -ENODEV;
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;
248 static void maybe_msleep(unsigned long ms)
250 /* During early boot, IRQs are disabled, use mdelay */
251 if (irqs_disabled())
252 mdelay(ms);
253 else
254 msleep(ms);
257 int hvsilib_read_mctrl(struct hvsi_priv *pv)
259 struct hvsi_query q;
260 int rc, timeout;
262 pr_devel("HVSI@%x: Querying modem control status...\n",
263 pv->termno);
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;
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);
284 return -EIO;
287 int hvsilib_write_mctrl(struct hvsi_priv *pv, int dtr)
289 struct hvsi_control ctrl;
290 unsigned short mctrl;
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;
301 pr_devel("HVSI@%x: %s DTR...\n", pv->termno,
302 dtr ? "Setting" : "Clearing");
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);
312 void hvsilib_establish(struct hvsi_priv *pv)
314 int timeout;
316 pr_devel("HVSI@%x: Establishing...\n", pv->termno);
318 /* Try for up to 200ms, there can be a packet to
319 * start the process waiting for us...
321 for (timeout = 0; timeout < 20; timeout++) {
322 if (pv->established)
323 goto established;
324 if (!hvsi_get_packet(pv))
325 maybe_msleep(10);
328 /* Failed, send a close connection packet just
329 * in case
331 pr_devel("HVSI@%x: ... sending close\n", pv->termno);
333 hvsi_send_close(pv);
335 /* Then restart handshake */
337 pr_devel("HVSI@%x: ... restarting handshake\n", pv->termno);
339 hvsi_start_handshake(pv);
341 pr_devel("HVSI@%x: ... waiting handshake\n", pv->termno);
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);
351 if (!pv->established) {
352 pr_devel("HVSI@%x: Timeout handshaking, giving up !\n",
353 pv->termno);
354 return;
356 established:
357 /* Query modem control lines */
359 pr_devel("HVSI@%x: ... established, reading mctrl\n", pv->termno);
361 hvsilib_read_mctrl(pv);
363 /* Set our own DTR */
365 pr_devel("HVSI@%x: ... setting mctrl\n", pv->termno);
367 hvsilib_write_mctrl(pv, 1);
369 /* Set the opened flag so reads are allowed */
370 wmb();
371 pv->opened = 1;
374 int hvsilib_open(struct hvsi_priv *pv, struct hvc_struct *hp)
376 pr_devel("HVSI@%x: open !\n", pv->termno);
378 /* Keep track of the tty data structure */
379 pv->tty = tty_port_tty_get(&hp->port);
381 hvsilib_establish(pv);
383 return 0;
386 void hvsilib_close(struct hvsi_priv *pv, struct hvc_struct *hp)
388 unsigned long flags;
390 pr_devel("HVSI@%x: close !\n", pv->termno);
392 if (!pv->is_console) {
393 pr_devel("HVSI@%x: Not a console, tearing down\n",
394 pv->termno);
396 /* Clear opened, synchronize with khvcd */
397 spin_lock_irqsave(&hp->lock, flags);
398 pv->opened = 0;
399 spin_unlock_irqrestore(&hp->lock, flags);
401 /* Clear our own DTR */
402 if (!pv->tty || (pv->tty->termios.c_cflag & HUPCL))
403 hvsilib_write_mctrl(pv, 0);
405 /* Tear down the connection */
406 hvsi_send_close(pv);
409 tty_kref_put(pv->tty);
410 pv->tty = NULL;
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)
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;