drivers/tty/hvc/hvsi.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2004 Hollis Blanchard <hollisb@us.ibm.com>, IBM
   4  */
   5
   6 /* Host Virtual Serial Interface (HVSI) is a protocol between the hosted OS
   7  * and the service processor on IBM pSeries servers. On these servers, there
   8  * are no serial ports under the OS's control, and sometimes there is no other
   9  * console available either. However, the service processor has two standard
  10  * serial ports, so this over-complicated protocol allows the OS to control
  11  * those ports by proxy.
  12  *
  13  * Besides data, the procotol supports the reading/writing of the serial
  14  * port's DTR line, and the reading of the CD line. This is to allow the OS to
  15  * control a modem attached to the service processor's serial port. Note that
  16  * the OS cannot change the speed of the port through this protocol.
  17  */
  18
  19 #undef DEBUG
  20
  21 #include <linux/console.h>
  22 #include <linux/ctype.h>
  23 #include <linux/delay.h>
  24 #include <linux/init.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/module.h>
  27 #include <linux/major.h>
  28 #include <linux/kernel.h>
  29 #include <linux/spinlock.h>
  30 #include <linux/sysrq.h>
  31 #include <linux/tty.h>
  32 #include <linux/tty_flip.h>
  33 #include <asm/hvcall.h>
  34 #include <asm/hvconsole.h>
  35 #include <asm/prom.h>
  36 #include <linux/uaccess.h>
  37 #include <asm/vio.h>
  38 #include <asm/param.h>
  39 #include <asm/hvsi.h>
  40
  41 #define HVSI_MAJOR      229
  42 #define HVSI_MINOR      128
  43 #define MAX_NR_HVSI_CONSOLES 4
  44
  45 #define HVSI_TIMEOUT (5*HZ)
  46 #define HVSI_VERSION 1
  47 #define HVSI_MAX_PACKET 256
  48 #define HVSI_MAX_READ 16
  49 #define HVSI_MAX_OUTGOING_DATA 12
  50 #define N_OUTBUF 12
  51
  52 /*
  53  * we pass data via two 8-byte registers, so we would like our char arrays
  54  * properly aligned for those loads.
  55  */
  56 #define __ALIGNED__     __attribute__((__aligned__(sizeof(long))))
  57
  58 struct hvsi_struct {
  59         struct tty_port port;
  60         struct delayed_work writer;
  61         struct work_struct handshaker;
  62         wait_queue_head_t emptyq; /* woken when outbuf is emptied */
  63         wait_queue_head_t stateq; /* woken when HVSI state changes */
  64         spinlock_t lock;
  65         int index;
  66         uint8_t throttle_buf[128];
  67         uint8_t outbuf[N_OUTBUF]; /* to implement write_room and chars_in_buffer */
  68         /* inbuf is for packet reassembly. leave a little room for leftovers. */
  69         uint8_t inbuf[HVSI_MAX_PACKET + HVSI_MAX_READ];
  70         uint8_t *inbuf_end;
  71         int n_throttle;
  72         int n_outbuf;
  73         uint32_t vtermno;
  74         uint32_t virq;
  75         atomic_t seqno; /* HVSI packet sequence number */
  76         uint16_t mctrl;
  77         uint8_t state;  /* HVSI protocol state */
  78         uint8_t flags;
  79 #ifdef CONFIG_MAGIC_SYSRQ
  80         uint8_t sysrq;
  81 #endif /* CONFIG_MAGIC_SYSRQ */
  82 };
  83 static struct hvsi_struct hvsi_ports[MAX_NR_HVSI_CONSOLES];
  84
  85 static struct tty_driver *hvsi_driver;
  86 static int hvsi_count;
  87 static int (*hvsi_wait)(struct hvsi_struct *hp, int state);
  88
  89 enum HVSI_PROTOCOL_STATE {
  90         HVSI_CLOSED,
  91         HVSI_WAIT_FOR_VER_RESPONSE,
  92         HVSI_WAIT_FOR_VER_QUERY,
  93         HVSI_OPEN,
  94         HVSI_WAIT_FOR_MCTRL_RESPONSE,
  95         HVSI_FSP_DIED,
  96 };
  97 #define HVSI_CONSOLE 0x1
  98
  99 static inline int is_console(struct hvsi_struct *hp)
 100 {
 101         return hp->flags & HVSI_CONSOLE;
 102 }
 103
 104 static inline int is_open(struct hvsi_struct *hp)
 105 {
 106         /* if we're waiting for an mctrl then we're already open */
 107         return (hp->state == HVSI_OPEN)
 108                         || (hp->state == HVSI_WAIT_FOR_MCTRL_RESPONSE);
 109 }
 110
 111 static inline void print_state(struct hvsi_struct *hp)
 112 {
 113 #ifdef DEBUG
 114         static const char *state_names[] = {
 115                 "HVSI_CLOSED",
 116                 "HVSI_WAIT_FOR_VER_RESPONSE",
 117                 "HVSI_WAIT_FOR_VER_QUERY",
 118                 "HVSI_OPEN",
 119                 "HVSI_WAIT_FOR_MCTRL_RESPONSE",
 120                 "HVSI_FSP_DIED",
 121         };
 122         const char *name = (hp->state < ARRAY_SIZE(state_names))
 123                 ? state_names[hp->state] : "UNKNOWN";
 124
 125         pr_debug("hvsi%i: state = %s\n", hp->index, name);
 126 #endif /* DEBUG */
 127 }
 128
 129 static inline void __set_state(struct hvsi_struct *hp, int state)
 130 {
 131         hp->state = state;
 132         print_state(hp);
 133         wake_up_all(&hp->stateq);
 134 }
 135
 136 static inline void set_state(struct hvsi_struct *hp, int state)
 137 {
 138         unsigned long flags;
 139
 140         spin_lock_irqsave(&hp->lock, flags);
 141         __set_state(hp, state);
 142         spin_unlock_irqrestore(&hp->lock, flags);
 143 }
 144
 145 static inline int len_packet(const uint8_t *packet)
 146 {
 147         return (int)((struct hvsi_header *)packet)->len;
 148 }
 149
 150 static inline int is_header(const uint8_t *packet)
 151 {
 152         struct hvsi_header *header = (struct hvsi_header *)packet;
 153         return header->type >= VS_QUERY_RESPONSE_PACKET_HEADER;
 154 }
 155
 156 static inline int got_packet(const struct hvsi_struct *hp, uint8_t *packet)
 157 {
 158         if (hp->inbuf_end < packet + sizeof(struct hvsi_header))
 159                 return 0; /* don't even have the packet header */
 160
 161         if (hp->inbuf_end < (packet + len_packet(packet)))
 162                 return 0; /* don't have the rest of the packet */
 163
 164         return 1;
 165 }
 166
 167 /* shift remaining bytes in packetbuf down */
 168 static void compact_inbuf(struct hvsi_struct *hp, uint8_t *read_to)
 169 {
 170         int remaining = (int)(hp->inbuf_end - read_to);
 171
 172         pr_debug("%s: %i chars remain\n", __func__, remaining);
 173
 174         if (read_to != hp->inbuf)
 175                 memmove(hp->inbuf, read_to, remaining);
 176
 177         hp->inbuf_end = hp->inbuf + remaining;
 178 }
 179
 180 #ifdef DEBUG
 181 #define dbg_dump_packet(packet) dump_packet(packet)
 182 #define dbg_dump_hex(data, len) dump_hex(data, len)
 183 #else
 184 #define dbg_dump_packet(packet) do { } while (0)
 185 #define dbg_dump_hex(data, len) do { } while (0)
 186 #endif
 187
 188 static void dump_hex(const uint8_t *data, int len)
 189 {
 190         int i;
 191
 192         printk("    ");
 193         for (i=0; i < len; i++)
 194                 printk("%.2x", data[i]);
 195
 196         printk("\n    ");
 197         for (i=0; i < len; i++) {
 198                 if (isprint(data[i]))
 199                         printk("%c", data[i]);
 200                 else
 201                         printk(".");
 202         }
 203         printk("\n");
 204 }
 205
 206 static void dump_packet(uint8_t *packet)
 207 {
 208         struct hvsi_header *header = (struct hvsi_header *)packet;
 209
 210         printk("type 0x%x, len %i, seqno %i:\n", header->type, header->len,
 211                         header->seqno);
 212
 213         dump_hex(packet, header->len);
 214 }
 215
 216 static int hvsi_read(struct hvsi_struct *hp, char *buf, int count)
 217 {
 218         unsigned long got;
 219
 220         got = hvc_get_chars(hp->vtermno, buf, count);
 221
 222         return got;
 223 }
 224
 225 static void hvsi_recv_control(struct hvsi_struct *hp, uint8_t *packet,
 226         struct tty_struct *tty, struct hvsi_struct **to_handshake)
 227 {
 228         struct hvsi_control *header = (struct hvsi_control *)packet;
 229
 230         switch (be16_to_cpu(header->verb)) {
 231                 case VSV_MODEM_CTL_UPDATE:
 232                         if ((be32_to_cpu(header->word) & HVSI_TSCD) == 0) {
 233                                 /* CD went away; no more connection */
 234                                 pr_debug("hvsi%i: CD dropped\n", hp->index);
 235                                 hp->mctrl &= TIOCM_CD;
 236                                 if (tty && !C_CLOCAL(tty))
 237                                         tty_hangup(tty);
 238                         }
 239                         break;
 240                 case VSV_CLOSE_PROTOCOL:
 241                         pr_debug("hvsi%i: service processor came back\n", hp->index);
 242                         if (hp->state != HVSI_CLOSED) {
 243                                 *to_handshake = hp;
 244                         }
 245                         break;
 246                 default:
 247                         printk(KERN_WARNING "hvsi%i: unknown HVSI control packet: ",
 248                                 hp->index);
 249                         dump_packet(packet);
 250                         break;
 251         }
 252 }
 253
 254 static void hvsi_recv_response(struct hvsi_struct *hp, uint8_t *packet)
 255 {
 256         struct hvsi_query_response *resp = (struct hvsi_query_response *)packet;
 257         uint32_t mctrl_word;
 258
 259         switch (hp->state) {
 260                 case HVSI_WAIT_FOR_VER_RESPONSE:
 261                         __set_state(hp, HVSI_WAIT_FOR_VER_QUERY);
 262                         break;
 263                 case HVSI_WAIT_FOR_MCTRL_RESPONSE:
 264                         hp->mctrl = 0;
 265                         mctrl_word = be32_to_cpu(resp->u.mctrl_word);
 266                         if (mctrl_word & HVSI_TSDTR)
 267                                 hp->mctrl |= TIOCM_DTR;
 268                         if (mctrl_word & HVSI_TSCD)
 269                                 hp->mctrl |= TIOCM_CD;
 270                         __set_state(hp, HVSI_OPEN);
 271                         break;
 272                 default:
 273                         printk(KERN_ERR "hvsi%i: unexpected query response: ", hp->index);
 274                         dump_packet(packet);
 275                         break;
 276         }
 277 }
 278
 279 /* respond to service processor's version query */
 280 static int hvsi_version_respond(struct hvsi_struct *hp, uint16_t query_seqno)
 281 {
 282         struct hvsi_query_response packet __ALIGNED__;
 283         int wrote;
 284
 285         packet.hdr.type = VS_QUERY_RESPONSE_PACKET_HEADER;
 286         packet.hdr.len = sizeof(struct hvsi_query_response);
 287         packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
 288         packet.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
 289         packet.u.version = HVSI_VERSION;
 290         packet.query_seqno = cpu_to_be16(query_seqno+1);
 291
 292         pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
 293         dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
 294
 295         wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
 296         if (wrote != packet.hdr.len) {
 297                 printk(KERN_ERR "hvsi%i: couldn't send query response!\n",
 298                         hp->index);
 299                 return -EIO;
 300         }
 301
 302         return 0;
 303 }
 304
 305 static void hvsi_recv_query(struct hvsi_struct *hp, uint8_t *packet)
 306 {
 307         struct hvsi_query *query = (struct hvsi_query *)packet;
 308
 309         switch (hp->state) {
 310                 case HVSI_WAIT_FOR_VER_QUERY:
 311                         hvsi_version_respond(hp, be16_to_cpu(query->hdr.seqno));
 312                         __set_state(hp, HVSI_OPEN);
 313                         break;
 314                 default:
 315                         printk(KERN_ERR "hvsi%i: unexpected query: ", hp->index);
 316                         dump_packet(packet);
 317                         break;
 318         }
 319 }
 320
 321 static void hvsi_insert_chars(struct hvsi_struct *hp, const char *buf, int len)
 322 {
 323         int i;
 324
 325         for (i=0; i < len; i++) {
 326                 char c = buf[i];
 327 #ifdef CONFIG_MAGIC_SYSRQ
 328                 if (c == '\0') {
 329                         hp->sysrq = 1;
 330                         continue;
 331                 } else if (hp->sysrq) {
 332                         handle_sysrq(c);
 333                         hp->sysrq = 0;
 334                         continue;
 335                 }
 336 #endif /* CONFIG_MAGIC_SYSRQ */
 337                 tty_insert_flip_char(&hp->port, c, 0);
 338         }
 339 }
 340
 341 /*
 342  * We could get 252 bytes of data at once here. But the tty layer only
 343  * throttles us at TTY_THRESHOLD_THROTTLE (128) bytes, so we could overflow
 344  * it. Accordingly we won't send more than 128 bytes at a time to the flip
 345  * buffer, which will give the tty buffer a chance to throttle us. Should the
 346  * value of TTY_THRESHOLD_THROTTLE change in n_tty.c, this code should be
 347  * revisited.
 348  */
 349 #define TTY_THRESHOLD_THROTTLE 128
 350 static bool hvsi_recv_data(struct hvsi_struct *hp, const uint8_t *packet)
 351 {
 352         const struct hvsi_header *header = (const struct hvsi_header *)packet;
 353         const uint8_t *data = packet + sizeof(struct hvsi_header);
 354         int datalen = header->len - sizeof(struct hvsi_header);
 355         int overflow = datalen - TTY_THRESHOLD_THROTTLE;
 356
 357         pr_debug("queueing %i chars '%.*s'\n", datalen, datalen, data);
 358
 359         if (datalen == 0)
 360                 return false;
 361
 362         if (overflow > 0) {
 363                 pr_debug("%s: got >TTY_THRESHOLD_THROTTLE bytes\n", __func__);
 364                 datalen = TTY_THRESHOLD_THROTTLE;
 365         }
 366
 367         hvsi_insert_chars(hp, data, datalen);
 368
 369         if (overflow > 0) {
 370                 /*
 371                  * we still have more data to deliver, so we need to save off the
 372                  * overflow and send it later
 373                  */
 374                 pr_debug("%s: deferring overflow\n", __func__);
 375                 memcpy(hp->throttle_buf, data + TTY_THRESHOLD_THROTTLE, overflow);
 376                 hp->n_throttle = overflow;
 377         }
 378
 379         return true;
 380 }
 381
 382 /*
 383  * Returns true/false indicating data successfully read from hypervisor.
 384  * Used both to get packets for tty connections and to advance the state
 385  * machine during console handshaking (in which case tty = NULL and we ignore
 386  * incoming data).
 387  */
 388 static int hvsi_load_chunk(struct hvsi_struct *hp, struct tty_struct *tty,
 389                 struct hvsi_struct **handshake)
 390 {
 391         uint8_t *packet = hp->inbuf;
 392         int chunklen;
 393         bool flip = false;
 394
 395         *handshake = NULL;
 396
 397         chunklen = hvsi_read(hp, hp->inbuf_end, HVSI_MAX_READ);
 398         if (chunklen == 0) {
 399                 pr_debug("%s: 0-length read\n", __func__);
 400                 return 0;
 401         }
 402
 403         pr_debug("%s: got %i bytes\n", __func__, chunklen);
 404         dbg_dump_hex(hp->inbuf_end, chunklen);
 405
 406         hp->inbuf_end += chunklen;
 407
 408         /* handle all completed packets */
 409         while ((packet < hp->inbuf_end) && got_packet(hp, packet)) {
 410                 struct hvsi_header *header = (struct hvsi_header *)packet;
 411
 412                 if (!is_header(packet)) {
 413                         printk(KERN_ERR "hvsi%i: got malformed packet\n", hp->index);
 414                         /* skip bytes until we find a header or run out of data */
 415                         while ((packet < hp->inbuf_end) && (!is_header(packet)))
 416                                 packet++;
 417                         continue;
 418                 }
 419
 420                 pr_debug("%s: handling %i-byte packet\n", __func__,
 421                                 len_packet(packet));
 422                 dbg_dump_packet(packet);
 423
 424                 switch (header->type) {
 425                         case VS_DATA_PACKET_HEADER:
 426                                 if (!is_open(hp))
 427                                         break;
 428                                 flip = hvsi_recv_data(hp, packet);
 429                                 break;
 430                         case VS_CONTROL_PACKET_HEADER:
 431                                 hvsi_recv_control(hp, packet, tty, handshake);
 432                                 break;
 433                         case VS_QUERY_RESPONSE_PACKET_HEADER:
 434                                 hvsi_recv_response(hp, packet);
 435                                 break;
 436                         case VS_QUERY_PACKET_HEADER:
 437                                 hvsi_recv_query(hp, packet);
 438                                 break;
 439                         default:
 440                                 printk(KERN_ERR "hvsi%i: unknown HVSI packet type 0x%x\n",
 441                                                 hp->index, header->type);
 442                                 dump_packet(packet);
 443                                 break;
 444                 }
 445
 446                 packet += len_packet(packet);
 447
 448                 if (*handshake) {
 449                         pr_debug("%s: handshake\n", __func__);
 450                         break;
 451                 }
 452         }
 453
 454         compact_inbuf(hp, packet);
 455
 456         if (flip)
 457                 tty_flip_buffer_push(&hp->port);
 458
 459         return 1;
 460 }
 461
 462 static void hvsi_send_overflow(struct hvsi_struct *hp)
 463 {
 464         pr_debug("%s: delivering %i bytes overflow\n", __func__,
 465                         hp->n_throttle);
 466
 467         hvsi_insert_chars(hp, hp->throttle_buf, hp->n_throttle);
 468         hp->n_throttle = 0;
 469 }
 470
 471 /*
 472  * must get all pending data because we only get an irq on empty->non-empty
 473  * transition
 474  */
 475 static irqreturn_t hvsi_interrupt(int irq, void *arg)
 476 {
 477         struct hvsi_struct *hp = (struct hvsi_struct *)arg;
 478         struct hvsi_struct *handshake;
 479         struct tty_struct *tty;
 480         unsigned long flags;
 481         int again = 1;
 482
 483         pr_debug("%s\n", __func__);
 484
 485         tty = tty_port_tty_get(&hp->port);
 486
 487         while (again) {
 488                 spin_lock_irqsave(&hp->lock, flags);
 489                 again = hvsi_load_chunk(hp, tty, &handshake);
 490                 spin_unlock_irqrestore(&hp->lock, flags);
 491
 492                 if (handshake) {
 493                         pr_debug("hvsi%i: attempting re-handshake\n", handshake->index);
 494                         schedule_work(&handshake->handshaker);
 495                 }
 496         }
 497
 498         spin_lock_irqsave(&hp->lock, flags);
 499         if (tty && hp->n_throttle && !tty_throttled(tty)) {
 500                 /* we weren't hung up and we weren't throttled, so we can
 501                  * deliver the rest now */
 502                 hvsi_send_overflow(hp);
 503                 tty_flip_buffer_push(&hp->port);
 504         }
 505         spin_unlock_irqrestore(&hp->lock, flags);
 506
 507         tty_kref_put(tty);
 508
 509         return IRQ_HANDLED;
 510 }
 511
 512 /* for boot console, before the irq handler is running */
 513 static int __init poll_for_state(struct hvsi_struct *hp, int state)
 514 {
 515         unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
 516
 517         for (;;) {
 518                 hvsi_interrupt(hp->virq, (void *)hp); /* get pending data */
 519
 520                 if (hp->state == state)
 521                         return 0;
 522
 523                 mdelay(5);
 524                 if (time_after(jiffies, end_jiffies))
 525                         return -EIO;
 526         }
 527 }
 528
 529 /* wait for irq handler to change our state */
 530 static int wait_for_state(struct hvsi_struct *hp, int state)
 531 {
 532         int ret = 0;
 533
 534         if (!wait_event_timeout(hp->stateq, (hp->state == state), HVSI_TIMEOUT))
 535                 ret = -EIO;
 536
 537         return ret;
 538 }
 539
 540 static int hvsi_query(struct hvsi_struct *hp, uint16_t verb)
 541 {
 542         struct hvsi_query packet __ALIGNED__;
 543         int wrote;
 544
 545         packet.hdr.type = VS_QUERY_PACKET_HEADER;
 546         packet.hdr.len = sizeof(struct hvsi_query);
 547         packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
 548         packet.verb = cpu_to_be16(verb);
 549
 550         pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
 551         dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
 552
 553         wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
 554         if (wrote != packet.hdr.len) {
 555                 printk(KERN_ERR "hvsi%i: couldn't send query (%i)!\n", hp->index,
 556                         wrote);
 557                 return -EIO;
 558         }
 559
 560         return 0;
 561 }
 562
 563 static int hvsi_get_mctrl(struct hvsi_struct *hp)
 564 {
 565         int ret;
 566
 567         set_state(hp, HVSI_WAIT_FOR_MCTRL_RESPONSE);
 568         hvsi_query(hp, VSV_SEND_MODEM_CTL_STATUS);
 569
 570         ret = hvsi_wait(hp, HVSI_OPEN);
 571         if (ret < 0) {
 572                 printk(KERN_ERR "hvsi%i: didn't get modem flags\n", hp->index);
 573                 set_state(hp, HVSI_OPEN);
 574                 return ret;
 575         }
 576
 577         pr_debug("%s: mctrl 0x%x\n", __func__, hp->mctrl);
 578
 579         return 0;
 580 }
 581
 582 /* note that we can only set DTR */
 583 static int hvsi_set_mctrl(struct hvsi_struct *hp, uint16_t mctrl)
 584 {
 585         struct hvsi_control packet __ALIGNED__;
 586         int wrote;
 587
 588         packet.hdr.type = VS_CONTROL_PACKET_HEADER;
 589         packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
 590         packet.hdr.len = sizeof(struct hvsi_control);
 591         packet.verb = cpu_to_be16(VSV_SET_MODEM_CTL);
 592         packet.mask = cpu_to_be32(HVSI_TSDTR);
 593
 594         if (mctrl & TIOCM_DTR)
 595                 packet.word = cpu_to_be32(HVSI_TSDTR);
 596
 597         pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
 598         dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
 599
 600         wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
 601         if (wrote != packet.hdr.len) {
 602                 printk(KERN_ERR "hvsi%i: couldn't set DTR!\n", hp->index);
 603                 return -EIO;
 604         }
 605
 606         return 0;
 607 }
 608
 609 static void hvsi_drain_input(struct hvsi_struct *hp)
 610 {
 611         uint8_t buf[HVSI_MAX_READ] __ALIGNED__;
 612         unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
 613
 614         while (time_before(end_jiffies, jiffies))
 615                 if (0 == hvsi_read(hp, buf, HVSI_MAX_READ))
 616                         break;
 617 }
 618
 619 static int hvsi_handshake(struct hvsi_struct *hp)
 620 {
 621         int ret;
 622
 623         /*
 624          * We could have a CLOSE or other data waiting for us before we even try
 625          * to open; try to throw it all away so we don't get confused. (CLOSE
 626          * is the first message sent up the pipe when the FSP comes online. We
 627          * need to distinguish between "it came up a while ago and we're the first
 628          * user" and "it was just reset before it saw our handshake packet".)
 629          */
 630         hvsi_drain_input(hp);
 631
 632         set_state(hp, HVSI_WAIT_FOR_VER_RESPONSE);
 633         ret = hvsi_query(hp, VSV_SEND_VERSION_NUMBER);
 634         if (ret < 0) {
 635                 printk(KERN_ERR "hvsi%i: couldn't send version query\n", hp->index);
 636                 return ret;
 637         }
 638
 639         ret = hvsi_wait(hp, HVSI_OPEN);
 640         if (ret < 0)
 641                 return ret;
 642
 643         return 0;
 644 }
 645
 646 static void hvsi_handshaker(struct work_struct *work)
 647 {
 648         struct hvsi_struct *hp =
 649                 container_of(work, struct hvsi_struct, handshaker);
 650
 651         if (hvsi_handshake(hp) >= 0)
 652                 return;
 653
 654         printk(KERN_ERR "hvsi%i: re-handshaking failed\n", hp->index);
 655         if (is_console(hp)) {
 656                 /*
 657                  * ttys will re-attempt the handshake via hvsi_open, but
 658                  * the console will not.
 659                  */
 660                 printk(KERN_ERR "hvsi%i: lost console!\n", hp->index);
 661         }
 662 }
 663
 664 static int hvsi_put_chars(struct hvsi_struct *hp, const char *buf, int count)
 665 {
 666         struct hvsi_data packet __ALIGNED__;
 667         int ret;
 668
 669         BUG_ON(count > HVSI_MAX_OUTGOING_DATA);
 670
 671         packet.hdr.type = VS_DATA_PACKET_HEADER;
 672         packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
 673         packet.hdr.len = count + sizeof(struct hvsi_header);
 674         memcpy(&packet.data, buf, count);
 675
 676         ret = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
 677         if (ret == packet.hdr.len) {
 678                 /* return the number of chars written, not the packet length */
 679                 return count;
 680         }
 681         return ret; /* return any errors */
 682 }
 683
 684 static void hvsi_close_protocol(struct hvsi_struct *hp)
 685 {
 686         struct hvsi_control packet __ALIGNED__;
 687
 688         packet.hdr.type = VS_CONTROL_PACKET_HEADER;
 689         packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
 690         packet.hdr.len = 6;
 691         packet.verb = cpu_to_be16(VSV_CLOSE_PROTOCOL);
 692
 693         pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
 694         dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
 695
 696         hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
 697 }
 698
 699 static int hvsi_open(struct tty_struct *tty, struct file *filp)
 700 {
 701         struct hvsi_struct *hp;
 702         unsigned long flags;
 703         int ret;
 704
 705         pr_debug("%s\n", __func__);
 706
 707         hp = &hvsi_ports[tty->index];
 708
 709         tty->driver_data = hp;
 710
 711         mb();
 712         if (hp->state == HVSI_FSP_DIED)
 713                 return -EIO;
 714
 715         tty_port_tty_set(&hp->port, tty);
 716         spin_lock_irqsave(&hp->lock, flags);
 717         hp->port.count++;
 718         atomic_set(&hp->seqno, 0);
 719         h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
 720         spin_unlock_irqrestore(&hp->lock, flags);
 721
 722         if (is_console(hp))
 723                 return 0; /* this has already been handshaked as the console */
 724
 725         ret = hvsi_handshake(hp);
 726         if (ret < 0) {
 727                 printk(KERN_ERR "%s: HVSI handshaking failed\n", tty->name);
 728                 return ret;
 729         }
 730
 731         ret = hvsi_get_mctrl(hp);
 732         if (ret < 0) {
 733                 printk(KERN_ERR "%s: couldn't get initial modem flags\n", tty->name);
 734                 return ret;
 735         }
 736
 737         ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
 738         if (ret < 0) {
 739                 printk(KERN_ERR "%s: couldn't set DTR\n", tty->name);
 740                 return ret;
 741         }
 742
 743         return 0;
 744 }
 745
 746 /* wait for hvsi_write_worker to empty hp->outbuf */
 747 static void hvsi_flush_output(struct hvsi_struct *hp)
 748 {
 749         wait_event_timeout(hp->emptyq, (hp->n_outbuf <= 0), HVSI_TIMEOUT);
 750
 751         /* 'writer' could still be pending if it didn't see n_outbuf = 0 yet */
 752         cancel_delayed_work_sync(&hp->writer);
 753         flush_work(&hp->handshaker);
 754
 755         /*
 756          * it's also possible that our timeout expired and hvsi_write_worker
 757          * didn't manage to push outbuf. poof.
 758          */
 759         hp->n_outbuf = 0;
 760 }
 761
 762 static void hvsi_close(struct tty_struct *tty, struct file *filp)
 763 {
 764         struct hvsi_struct *hp = tty->driver_data;
 765         unsigned long flags;
 766
 767         pr_debug("%s\n", __func__);
 768
 769         if (tty_hung_up_p(filp))
 770                 return;
 771
 772         spin_lock_irqsave(&hp->lock, flags);
 773
 774         if (--hp->port.count == 0) {
 775                 tty_port_tty_set(&hp->port, NULL);
 776                 hp->inbuf_end = hp->inbuf; /* discard remaining partial packets */
 777
 778                 /* only close down connection if it is not the console */
 779                 if (!is_console(hp)) {
 780                         h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE); /* no more irqs */
 781                         __set_state(hp, HVSI_CLOSED);
 782                         /*
 783                          * any data delivered to the tty layer after this will be
 784                          * discarded (except for XON/XOFF)
 785                          */
 786                         tty->closing = 1;
 787
 788                         spin_unlock_irqrestore(&hp->lock, flags);
 789
 790                         /* let any existing irq handlers finish. no more will start. */
 791                         synchronize_irq(hp->virq);
 792
 793                         /* hvsi_write_worker will re-schedule until outbuf is empty. */
 794                         hvsi_flush_output(hp);
 795
 796                         /* tell FSP to stop sending data */
 797                         hvsi_close_protocol(hp);
 798
 799                         /*
 800                          * drain anything FSP is still in the middle of sending, and let
 801                          * hvsi_handshake drain the rest on the next open.
 802                          */
 803                         hvsi_drain_input(hp);
 804
 805                         spin_lock_irqsave(&hp->lock, flags);
 806                 }
 807         } else if (hp->port.count < 0)
 808                 printk(KERN_ERR "hvsi_close %lu: oops, count is %d\n",
 809                        hp - hvsi_ports, hp->port.count);
 810
 811         spin_unlock_irqrestore(&hp->lock, flags);
 812 }
 813
 814 static void hvsi_hangup(struct tty_struct *tty)
 815 {
 816         struct hvsi_struct *hp = tty->driver_data;
 817         unsigned long flags;
 818
 819         pr_debug("%s\n", __func__);
 820
 821         tty_port_tty_set(&hp->port, NULL);
 822
 823         spin_lock_irqsave(&hp->lock, flags);
 824         hp->port.count = 0;
 825         hp->n_outbuf = 0;
 826         spin_unlock_irqrestore(&hp->lock, flags);
 827 }
 828
 829 /* called with hp->lock held */
 830 static void hvsi_push(struct hvsi_struct *hp)
 831 {
 832         int n;
 833
 834         if (hp->n_outbuf <= 0)
 835                 return;
 836
 837         n = hvsi_put_chars(hp, hp->outbuf, hp->n_outbuf);
 838         if (n > 0) {
 839                 /* success */
 840                 pr_debug("%s: wrote %i chars\n", __func__, n);
 841                 hp->n_outbuf = 0;
 842         } else if (n == -EIO) {
 843                 __set_state(hp, HVSI_FSP_DIED);
 844                 printk(KERN_ERR "hvsi%i: service processor died\n", hp->index);
 845         }
 846 }
 847
 848 /* hvsi_write_worker will keep rescheduling itself until outbuf is empty */
 849 static void hvsi_write_worker(struct work_struct *work)
 850 {
 851         struct hvsi_struct *hp =
 852                 container_of(work, struct hvsi_struct, writer.work);
 853         unsigned long flags;
 854 #ifdef DEBUG
 855         static long start_j = 0;
 856
 857         if (start_j == 0)
 858                 start_j = jiffies;
 859 #endif /* DEBUG */
 860
 861         spin_lock_irqsave(&hp->lock, flags);
 862
 863         pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
 864
 865         if (!is_open(hp)) {
 866                 /*
 867                  * We could have a non-open connection if the service processor died
 868                  * while we were busily scheduling ourselves. In that case, it could
 869                  * be minutes before the service processor comes back, so only try
 870                  * again once a second.
 871                  */
 872                 schedule_delayed_work(&hp->writer, HZ);
 873                 goto out;
 874         }
 875
 876         hvsi_push(hp);
 877         if (hp->n_outbuf > 0)
 878                 schedule_delayed_work(&hp->writer, 10);
 879         else {
 880 #ifdef DEBUG
 881                 pr_debug("%s: outbuf emptied after %li jiffies\n", __func__,
 882                                 jiffies - start_j);
 883                 start_j = 0;
 884 #endif /* DEBUG */
 885                 wake_up_all(&hp->emptyq);
 886                 tty_port_tty_wakeup(&hp->port);
 887         }
 888
 889 out:
 890         spin_unlock_irqrestore(&hp->lock, flags);
 891 }
 892
 893 static int hvsi_write_room(struct tty_struct *tty)
 894 {
 895         struct hvsi_struct *hp = tty->driver_data;
 896
 897         return N_OUTBUF - hp->n_outbuf;
 898 }
 899
 900 static int hvsi_chars_in_buffer(struct tty_struct *tty)
 901 {
 902         struct hvsi_struct *hp = tty->driver_data;
 903
 904         return hp->n_outbuf;
 905 }
 906
 907 static int hvsi_write(struct tty_struct *tty,
 908                      const unsigned char *buf, int count)
 909 {
 910         struct hvsi_struct *hp = tty->driver_data;
 911         const char *source = buf;
 912         unsigned long flags;
 913         int total = 0;
 914         int origcount = count;
 915
 916         spin_lock_irqsave(&hp->lock, flags);
 917
 918         pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
 919
 920         if (!is_open(hp)) {
 921                 /* we're either closing or not yet open; don't accept data */
 922                 pr_debug("%s: not open\n", __func__);
 923                 goto out;
 924         }
 925
 926         /*
 927          * when the hypervisor buffer (16K) fills, data will stay in hp->outbuf
 928          * and hvsi_write_worker will be scheduled. subsequent hvsi_write() calls
 929          * will see there is no room in outbuf and return.
 930          */
 931         while ((count > 0) && (hvsi_write_room(tty) > 0)) {
 932                 int chunksize = min(count, hvsi_write_room(tty));
 933
 934                 BUG_ON(hp->n_outbuf < 0);
 935                 memcpy(hp->outbuf + hp->n_outbuf, source, chunksize);
 936                 hp->n_outbuf += chunksize;
 937
 938                 total += chunksize;
 939                 source += chunksize;
 940                 count -= chunksize;
 941                 hvsi_push(hp);
 942         }
 943
 944         if (hp->n_outbuf > 0) {
 945                 /*
 946                  * we weren't able to write it all to the hypervisor.
 947                  * schedule another push attempt.
 948                  */
 949                 schedule_delayed_work(&hp->writer, 10);
 950         }
 951
 952 out:
 953         spin_unlock_irqrestore(&hp->lock, flags);
 954
 955         if (total != origcount)
 956                 pr_debug("%s: wanted %i, only wrote %i\n", __func__, origcount,
 957                         total);
 958
 959         return total;
 960 }
 961
 962 /*
 963  * I have never seen throttle or unthrottle called, so this little throttle
 964  * buffering scheme may or may not work.
 965  */
 966 static void hvsi_throttle(struct tty_struct *tty)
 967 {
 968         struct hvsi_struct *hp = tty->driver_data;
 969
 970         pr_debug("%s\n", __func__);
 971
 972         h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE);
 973 }
 974
 975 static void hvsi_unthrottle(struct tty_struct *tty)
 976 {
 977         struct hvsi_struct *hp = tty->driver_data;
 978         unsigned long flags;
 979
 980         pr_debug("%s\n", __func__);
 981
 982         spin_lock_irqsave(&hp->lock, flags);
 983         if (hp->n_throttle) {
 984                 hvsi_send_overflow(hp);
 985                 tty_flip_buffer_push(&hp->port);
 986         }
 987         spin_unlock_irqrestore(&hp->lock, flags);
 988
 989
 990         h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
 991 }
 992
 993 static int hvsi_tiocmget(struct tty_struct *tty)
 994 {
 995         struct hvsi_struct *hp = tty->driver_data;
 996
 997         hvsi_get_mctrl(hp);
 998         return hp->mctrl;
 999 }
1000
1001 static int hvsi_tiocmset(struct tty_struct *tty,
1002                                 unsigned int set, unsigned int clear)
1003 {
1004         struct hvsi_struct *hp = tty->driver_data;
1005         unsigned long flags;
1006         uint16_t new_mctrl;
1007
1008         /* we can only alter DTR */
1009         clear &= TIOCM_DTR;
1010         set &= TIOCM_DTR;
1011
1012         spin_lock_irqsave(&hp->lock, flags);
1013
1014         new_mctrl = (hp->mctrl & ~clear) | set;
1015
1016         if (hp->mctrl != new_mctrl) {
1017                 hvsi_set_mctrl(hp, new_mctrl);
1018                 hp->mctrl = new_mctrl;
1019         }
1020         spin_unlock_irqrestore(&hp->lock, flags);
1021
1022         return 0;
1023 }
1024
1025
1026 static const struct tty_operations hvsi_ops = {
1027         .open = hvsi_open,
1028         .close = hvsi_close,
1029         .write = hvsi_write,
1030         .hangup = hvsi_hangup,
1031         .write_room = hvsi_write_room,
1032         .chars_in_buffer = hvsi_chars_in_buffer,
1033         .throttle = hvsi_throttle,
1034         .unthrottle = hvsi_unthrottle,
1035         .tiocmget = hvsi_tiocmget,
1036         .tiocmset = hvsi_tiocmset,
1037 };
1038
1039 static int __init hvsi_init(void)
1040 {
1041         int i;
1042
1043         hvsi_driver = alloc_tty_driver(hvsi_count);
1044         if (!hvsi_driver)
1045                 return -ENOMEM;
1046
1047         hvsi_driver->driver_name = "hvsi";
1048         hvsi_driver->name = "hvsi";
1049         hvsi_driver->major = HVSI_MAJOR;
1050         hvsi_driver->minor_start = HVSI_MINOR;
1051         hvsi_driver->type = TTY_DRIVER_TYPE_SYSTEM;
1052         hvsi_driver->init_termios = tty_std_termios;
1053         hvsi_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL;
1054         hvsi_driver->init_termios.c_ispeed = 9600;
1055         hvsi_driver->init_termios.c_ospeed = 9600;
1056         hvsi_driver->flags = TTY_DRIVER_REAL_RAW;
1057         tty_set_operations(hvsi_driver, &hvsi_ops);
1058
1059         for (i=0; i < hvsi_count; i++) {
1060                 struct hvsi_struct *hp = &hvsi_ports[i];
1061                 int ret = 1;
1062
1063                 tty_port_link_device(&hp->port, hvsi_driver, i);
1064
1065                 ret = request_irq(hp->virq, hvsi_interrupt, 0, "hvsi", hp);
1066                 if (ret)
1067                         printk(KERN_ERR "HVSI: couldn't reserve irq 0x%x (error %i)\n",
1068                                 hp->virq, ret);
1069         }
1070         hvsi_wait = wait_for_state; /* irqs active now */
1071
1072         if (tty_register_driver(hvsi_driver))
1073                 panic("Couldn't register hvsi console driver\n");
1074
1075         printk(KERN_DEBUG "HVSI: registered %i devices\n", hvsi_count);
1076
1077         return 0;
1078 }
1079 device_initcall(hvsi_init);
1080
1081 /***** console (not tty) code: *****/
1082
1083 static void hvsi_console_print(struct console *console, const char *buf,
1084                 unsigned int count)
1085 {
1086         struct hvsi_struct *hp = &hvsi_ports[console->index];
1087         char c[HVSI_MAX_OUTGOING_DATA] __ALIGNED__;
1088         unsigned int i = 0, n = 0;
1089         int ret, donecr = 0;
1090
1091         mb();
1092         if (!is_open(hp))
1093                 return;
1094
1095         /*
1096          * ugh, we have to translate LF -> CRLF ourselves, in place.
1097          * copied from hvc_console.c:
1098          */
1099         while (count > 0 || i > 0) {
1100                 if (count > 0 && i < sizeof(c)) {
1101                         if (buf[n] == '\n' && !donecr) {
1102                                 c[i++] = '\r';
1103                                 donecr = 1;
1104                         } else {
1105                                 c[i++] = buf[n++];
1106                                 donecr = 0;
1107                                 --count;
1108                         }
1109                 } else {
1110                         ret = hvsi_put_chars(hp, c, i);
1111                         if (ret < 0)
1112                                 i = 0;
1113                         i -= ret;
1114                 }
1115         }
1116 }
1117
1118 static struct tty_driver *hvsi_console_device(struct console *console,
1119         int *index)
1120 {
1121         *index = console->index;
1122         return hvsi_driver;
1123 }
1124
1125 static int __init hvsi_console_setup(struct console *console, char *options)
1126 {
1127         struct hvsi_struct *hp;
1128         int ret;
1129
1130         if (console->index < 0 || console->index >= hvsi_count)
1131                 return -EINVAL;
1132         hp = &hvsi_ports[console->index];
1133
1134         /* give the FSP a chance to change the baud rate when we re-open */
1135         hvsi_close_protocol(hp);
1136
1137         ret = hvsi_handshake(hp);
1138         if (ret < 0)
1139                 return ret;
1140
1141         ret = hvsi_get_mctrl(hp);
1142         if (ret < 0)
1143                 return ret;
1144
1145         ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
1146         if (ret < 0)
1147                 return ret;
1148
1149         hp->flags |= HVSI_CONSOLE;
1150
1151         return 0;
1152 }
1153
1154 static struct console hvsi_console = {
1155         .name           = "hvsi",
1156         .write          = hvsi_console_print,
1157         .device         = hvsi_console_device,
1158         .setup          = hvsi_console_setup,
1159         .flags          = CON_PRINTBUFFER,
1160         .index          = -1,
1161 };
1162
1163 static int __init hvsi_console_init(void)
1164 {
1165         struct device_node *vty;
1166
1167         hvsi_wait = poll_for_state; /* no irqs yet; must poll */
1168
1169         /* search device tree for vty nodes */
1170         for_each_compatible_node(vty, "serial", "hvterm-protocol") {
1171                 struct hvsi_struct *hp;
1172                 const __be32 *vtermno, *irq;
1173
1174                 vtermno = of_get_property(vty, "reg", NULL);
1175                 irq = of_get_property(vty, "interrupts", NULL);
1176                 if (!vtermno || !irq)
1177                         continue;
1178
1179                 if (hvsi_count >= MAX_NR_HVSI_CONSOLES) {
1180                         of_node_put(vty);
1181                         break;
1182                 }
1183
1184                 hp = &hvsi_ports[hvsi_count];
1185                 INIT_DELAYED_WORK(&hp->writer, hvsi_write_worker);
1186                 INIT_WORK(&hp->handshaker, hvsi_handshaker);
1187                 init_waitqueue_head(&hp->emptyq);
1188                 init_waitqueue_head(&hp->stateq);
1189                 spin_lock_init(&hp->lock);
1190                 tty_port_init(&hp->port);
1191                 hp->index = hvsi_count;
1192                 hp->inbuf_end = hp->inbuf;
1193                 hp->state = HVSI_CLOSED;
1194                 hp->vtermno = be32_to_cpup(vtermno);
1195                 hp->virq = irq_create_mapping(NULL, be32_to_cpup(irq));
1196                 if (hp->virq == 0) {
1197                         printk(KERN_ERR "%s: couldn't create irq mapping for 0x%x\n",
1198                                __func__, be32_to_cpup(irq));
1199                         tty_port_destroy(&hp->port);
1200                         continue;
1201                 }
1202
1203                 hvsi_count++;
1204         }
1205
1206         if (hvsi_count)
1207                 register_console(&hvsi_console);
1208         return 0;
1209 }
1210 console_initcall(hvsi_console_init);