kernel/drivers/tty/hvc/hvsi_lib.c

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