drivers/tty/hvc/hvc_console.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2001 Anton Blanchard <[email protected]>, IBM
   4  * Copyright (C) 2001 Paul Mackerras <[email protected]>, IBM
   5  * Copyright (C) 2004 Benjamin Herrenschmidt <[email protected]>, IBM Corp.
   6  * Copyright (C) 2004 IBM Corporation
   7  *
   8  * Additional Author(s):
   9  *  Ryan S. Arnold <[email protected]>
  10  */
  11
  12 #include <linux/console.h>
  13 #include <linux/cpumask.h>
  14 #include <linux/init.h>
  15 #include <linux/kbd_kern.h>
  16 #include <linux/kernel.h>
  17 #include <linux/kthread.h>
  18 #include <linux/list.h>
  19 #include <linux/major.h>
  20 #include <linux/atomic.h>
  21 #include <linux/sysrq.h>
  22 #include <linux/tty.h>
  23 #include <linux/tty_flip.h>
  24 #include <linux/sched.h>
  25 #include <linux/spinlock.h>
  26 #include <linux/delay.h>
  27 #include <linux/freezer.h>
  28 #include <linux/slab.h>
  29 #include <linux/serial_core.h>
  30
  31 #include <linux/uaccess.h>
  32
  33 #include "hvc_console.h"
  34
  35 #define HVC_MAJOR       229
  36 #define HVC_MINOR       0
  37
  38 /*
  39  * Wait this long per iteration while trying to push buffered data to the
  40  * hypervisor before allowing the tty to complete a close operation.
  41  */
  42 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
  43
  44 /*
  45  * These sizes are most efficient for vio, because they are the
  46  * native transfer size. We could make them selectable in the
  47  * future to better deal with backends that want other buffer sizes.
  48  */
  49 #define N_OUTBUF        16
  50 #define N_INBUF         16
  51
  52 #define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
  53
  54 static struct tty_driver *hvc_driver;
  55 static struct task_struct *hvc_task;
  56
  57 /* Picks up late kicks after list walk but before schedule() */
  58 static int hvc_kicked;
  59
  60 /* hvc_init is triggered from hvc_alloc, i.e. only when actually used */
  61 static atomic_t hvc_needs_init __read_mostly = ATOMIC_INIT(-1);
  62
  63 static int hvc_init(void);
  64
  65 #ifdef CONFIG_MAGIC_SYSRQ
  66 static int sysrq_pressed;
  67 #endif
  68
  69 /* dynamic list of hvc_struct instances */
  70 static LIST_HEAD(hvc_structs);
  71
  72 /*
  73  * Protect the list of hvc_struct instances from inserts and removals during
  74  * list traversal.
  75  */
  76 static DEFINE_SPINLOCK(hvc_structs_lock);
  77
  78 /*
  79  * This value is used to assign a tty->index value to a hvc_struct based
  80  * upon order of exposure via hvc_probe(), when we can not match it to
  81  * a console candidate registered with hvc_instantiate().
  82  */
  83 static int last_hvc = -1;
  84
  85 /*
  86  * Do not call this function with either the hvc_structs_lock or the hvc_struct
  87  * lock held.  If successful, this function increments the kref reference
  88  * count against the target hvc_struct so it should be released when finished.
  89  */
  90 static struct hvc_struct *hvc_get_by_index(int index)
  91 {
  92         struct hvc_struct *hp;
  93         unsigned long flags;
  94
  95         spin_lock(&hvc_structs_lock);
  96
  97         list_for_each_entry(hp, &hvc_structs, next) {
  98                 spin_lock_irqsave(&hp->lock, flags);
  99                 if (hp->index == index) {
 100                         tty_port_get(&hp->port);
 101                         spin_unlock_irqrestore(&hp->lock, flags);
 102                         spin_unlock(&hvc_structs_lock);
 103                         return hp;
 104                 }
 105                 spin_unlock_irqrestore(&hp->lock, flags);
 106         }
 107         hp = NULL;
 108
 109         spin_unlock(&hvc_structs_lock);
 110         return hp;
 111 }
 112
 113
 114 /*
 115  * Initial console vtermnos for console API usage prior to full console
 116  * initialization.  Any vty adapter outside this range will not have usable
 117  * console interfaces but can still be used as a tty device.  This has to be
 118  * static because kmalloc will not work during early console init.
 119  */
 120 static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
 121 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
 122         {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
 123
 124 /*
 125  * Console APIs, NOT TTY.  These APIs are available immediately when
 126  * hvc_console_setup() finds adapters.
 127  */
 128
 129 static void hvc_console_print(struct console *co, const char *b,
 130                               unsigned count)
 131 {
 132         char c[N_OUTBUF] __ALIGNED__;
 133         unsigned i = 0, n = 0;
 134         int r, donecr = 0, index = co->index;
 135
 136         /* Console access attempt outside of acceptable console range. */
 137         if (index >= MAX_NR_HVC_CONSOLES)
 138                 return;
 139
 140         /* This console adapter was removed so it is not usable. */
 141         if (vtermnos[index] == -1)
 142                 return;
 143
 144         while (count > 0 || i > 0) {
 145                 if (count > 0 && i < sizeof(c)) {
 146                         if (b[n] == '\n' && !donecr) {
 147                                 c[i++] = '\r';
 148                                 donecr = 1;
 149                         } else {
 150                                 c[i++] = b[n++];
 151                                 donecr = 0;
 152                                 --count;
 153                         }
 154                 } else {
 155                         r = cons_ops[index]->put_chars(vtermnos[index], c, i);
 156                         if (r <= 0) {
 157                                 /* throw away characters on error
 158                                  * but spin in case of -EAGAIN */
 159                                 if (r != -EAGAIN)
 160                                         i = 0;
 161                         } else if (r > 0) {
 162                                 i -= r;
 163                                 if (i > 0)
 164                                         memmove(c, c+r, i);
 165                         }
 166                 }
 167         }
 168 }
 169
 170 static struct tty_driver *hvc_console_device(struct console *c, int *index)
 171 {
 172         if (vtermnos[c->index] == -1)
 173                 return NULL;
 174
 175         *index = c->index;
 176         return hvc_driver;
 177 }
 178
 179 static int hvc_console_setup(struct console *co, char *options)
 180 {
 181         if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
 182                 return -ENODEV;
 183
 184         if (vtermnos[co->index] == -1)
 185                 return -ENODEV;
 186
 187         return 0;
 188 }
 189
 190 static struct console hvc_console = {
 191         .name           = "hvc",
 192         .write          = hvc_console_print,
 193         .device         = hvc_console_device,
 194         .setup          = hvc_console_setup,
 195         .flags          = CON_PRINTBUFFER,
 196         .index          = -1,
 197 };
 198
 199 /*
 200  * Early console initialization.  Precedes driver initialization.
 201  *
 202  * (1) we are first, and the user specified another driver
 203  * -- index will remain -1
 204  * (2) we are first and the user specified no driver
 205  * -- index will be set to 0, then we will fail setup.
 206  * (3)  we are first and the user specified our driver
 207  * -- index will be set to user specified driver, and we will fail
 208  * (4) we are after driver, and this initcall will register us
 209  * -- if the user didn't specify a driver then the console will match
 210  *
 211  * Note that for cases 2 and 3, we will match later when the io driver
 212  * calls hvc_instantiate() and call register again.
 213  */
 214 static int __init hvc_console_init(void)
 215 {
 216         register_console(&hvc_console);
 217         return 0;
 218 }
 219 console_initcall(hvc_console_init);
 220
 221 /* callback when the kboject ref count reaches zero. */
 222 static void hvc_port_destruct(struct tty_port *port)
 223 {
 224         struct hvc_struct *hp = container_of(port, struct hvc_struct, port);
 225         unsigned long flags;
 226
 227         spin_lock(&hvc_structs_lock);
 228
 229         spin_lock_irqsave(&hp->lock, flags);
 230         list_del(&(hp->next));
 231         spin_unlock_irqrestore(&hp->lock, flags);
 232
 233         spin_unlock(&hvc_structs_lock);
 234
 235         kfree(hp);
 236 }
 237
 238 static void hvc_check_console(int index)
 239 {
 240         /* Already enabled, bail out */
 241         if (hvc_console.flags & CON_ENABLED)
 242                 return;
 243
 244         /* If this index is what the user requested, then register
 245          * now (setup won't fail at this point).  It's ok to just
 246          * call register again if previously .setup failed.
 247          */
 248         if (index == hvc_console.index)
 249                 register_console(&hvc_console);
 250 }
 251
 252 /*
 253  * hvc_instantiate() is an early console discovery method which locates
 254  * consoles * prior to the vio subsystem discovering them.  Hotplugged
 255  * vty adapters do NOT get an hvc_instantiate() callback since they
 256  * appear after early console init.
 257  */
 258 int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
 259 {
 260         struct hvc_struct *hp;
 261
 262         if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
 263                 return -1;
 264
 265         if (vtermnos[index] != -1)
 266                 return -1;
 267
 268         /* make sure no no tty has been registered in this index */
 269         hp = hvc_get_by_index(index);
 270         if (hp) {
 271                 tty_port_put(&hp->port);
 272                 return -1;
 273         }
 274
 275         vtermnos[index] = vtermno;
 276         cons_ops[index] = ops;
 277
 278         /* reserve all indices up to and including this index */
 279         if (last_hvc < index)
 280                 last_hvc = index;
 281
 282         /* check if we need to re-register the kernel console */
 283         hvc_check_console(index);
 284
 285         return 0;
 286 }
 287 EXPORT_SYMBOL_GPL(hvc_instantiate);
 288
 289 /* Wake the sleeping khvcd */
 290 void hvc_kick(void)
 291 {
 292         hvc_kicked = 1;
 293         wake_up_process(hvc_task);
 294 }
 295 EXPORT_SYMBOL_GPL(hvc_kick);
 296
 297 static void hvc_unthrottle(struct tty_struct *tty)
 298 {
 299         hvc_kick();
 300 }
 301
 302 static int hvc_install(struct tty_driver *driver, struct tty_struct *tty)
 303 {
 304         struct hvc_struct *hp;
 305         int rc;
 306
 307         /* Auto increments kref reference if found. */
 308         hp = hvc_get_by_index(tty->index);
 309         if (!hp)
 310                 return -ENODEV;
 311
 312         tty->driver_data = hp;
 313
 314         rc = tty_port_install(&hp->port, driver, tty);
 315         if (rc)
 316                 tty_port_put(&hp->port);
 317         return rc;
 318 }
 319
 320 /*
 321  * The TTY interface won't be used until after the vio layer has exposed the vty
 322  * adapter to the kernel.
 323  */
 324 static int hvc_open(struct tty_struct *tty, struct file * filp)
 325 {
 326         struct hvc_struct *hp = tty->driver_data;
 327         unsigned long flags;
 328         int rc = 0;
 329
 330         spin_lock_irqsave(&hp->port.lock, flags);
 331         /* Check and then increment for fast path open. */
 332         if (hp->port.count++ > 0) {
 333                 spin_unlock_irqrestore(&hp->port.lock, flags);
 334                 hvc_kick();
 335                 return 0;
 336         } /* else count == 0 */
 337         spin_unlock_irqrestore(&hp->port.lock, flags);
 338
 339         tty_port_tty_set(&hp->port, tty);
 340
 341         if (hp->ops->notifier_add)
 342                 rc = hp->ops->notifier_add(hp, hp->data);
 343
 344         /*
 345          * If the notifier fails we return an error.  The tty layer
 346          * will call hvc_close() after a failed open but we don't want to clean
 347          * up there so we'll clean up here and clear out the previously set
 348          * tty fields and return the kref reference.
 349          */
 350         if (rc) {
 351                 tty_port_tty_set(&hp->port, NULL);
 352                 tty->driver_data = NULL;
 353                 tty_port_put(&hp->port);
 354                 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
 355         } else
 356                 /* We are ready... raise DTR/RTS */
 357                 if (C_BAUD(tty))
 358                         if (hp->ops->dtr_rts)
 359                                 hp->ops->dtr_rts(hp, 1);
 360
 361         /* Force wakeup of the polling thread */
 362         hvc_kick();
 363
 364         return rc;
 365 }
 366
 367 static void hvc_close(struct tty_struct *tty, struct file * filp)
 368 {
 369         struct hvc_struct *hp;
 370         unsigned long flags;
 371
 372         if (tty_hung_up_p(filp))
 373                 return;
 374
 375         /*
 376          * No driver_data means that this close was issued after a failed
 377          * hvc_open by the tty layer's release_dev() function and we can just
 378          * exit cleanly because the kref reference wasn't made.
 379          */
 380         if (!tty->driver_data)
 381                 return;
 382
 383         hp = tty->driver_data;
 384
 385         spin_lock_irqsave(&hp->port.lock, flags);
 386
 387         if (--hp->port.count == 0) {
 388                 spin_unlock_irqrestore(&hp->port.lock, flags);
 389                 /* We are done with the tty pointer now. */
 390                 tty_port_tty_set(&hp->port, NULL);
 391
 392                 if (C_HUPCL(tty))
 393                         if (hp->ops->dtr_rts)
 394                                 hp->ops->dtr_rts(hp, 0);
 395
 396                 if (hp->ops->notifier_del)
 397                         hp->ops->notifier_del(hp, hp->data);
 398
 399                 /* cancel pending tty resize work */
 400                 cancel_work_sync(&hp->tty_resize);
 401
 402                 /*
 403                  * Chain calls chars_in_buffer() and returns immediately if
 404                  * there is no buffered data otherwise sleeps on a wait queue
 405                  * waking periodically to check chars_in_buffer().
 406                  */
 407                 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
 408         } else {
 409                 if (hp->port.count < 0)
 410                         printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
 411                                 hp->vtermno, hp->port.count);
 412                 spin_unlock_irqrestore(&hp->port.lock, flags);
 413         }
 414 }
 415
 416 static void hvc_cleanup(struct tty_struct *tty)
 417 {
 418         struct hvc_struct *hp = tty->driver_data;
 419
 420         tty_port_put(&hp->port);
 421 }
 422
 423 static void hvc_hangup(struct tty_struct *tty)
 424 {
 425         struct hvc_struct *hp = tty->driver_data;
 426         unsigned long flags;
 427
 428         if (!hp)
 429                 return;
 430
 431         /* cancel pending tty resize work */
 432         cancel_work_sync(&hp->tty_resize);
 433
 434         spin_lock_irqsave(&hp->port.lock, flags);
 435
 436         /*
 437          * The N_TTY line discipline has problems such that in a close vs
 438          * open->hangup case this can be called after the final close so prevent
 439          * that from happening for now.
 440          */
 441         if (hp->port.count <= 0) {
 442                 spin_unlock_irqrestore(&hp->port.lock, flags);
 443                 return;
 444         }
 445
 446         hp->port.count = 0;
 447         spin_unlock_irqrestore(&hp->port.lock, flags);
 448         tty_port_tty_set(&hp->port, NULL);
 449
 450         hp->n_outbuf = 0;
 451
 452         if (hp->ops->notifier_hangup)
 453                 hp->ops->notifier_hangup(hp, hp->data);
 454 }
 455
 456 /*
 457  * Push buffered characters whether they were just recently buffered or waiting
 458  * on a blocked hypervisor.  Call this function with hp->lock held.
 459  */
 460 static int hvc_push(struct hvc_struct *hp)
 461 {
 462         int n;
 463
 464         n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
 465         if (n <= 0) {
 466                 if (n == 0 || n == -EAGAIN) {
 467                         hp->do_wakeup = 1;
 468                         return 0;
 469                 }
 470                 /* throw away output on error; this happens when
 471                    there is no session connected to the vterm. */
 472                 hp->n_outbuf = 0;
 473         } else
 474                 hp->n_outbuf -= n;
 475         if (hp->n_outbuf > 0)
 476                 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
 477         else
 478                 hp->do_wakeup = 1;
 479
 480         return n;
 481 }
 482
 483 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
 484 {
 485         struct hvc_struct *hp = tty->driver_data;
 486         unsigned long flags;
 487         int rsize, written = 0;
 488
 489         /* This write was probably executed during a tty close. */
 490         if (!hp)
 491                 return -EPIPE;
 492
 493         /* FIXME what's this (unprotected) check for? */
 494         if (hp->port.count <= 0)
 495                 return -EIO;
 496
 497         spin_lock_irqsave(&hp->lock, flags);
 498
 499         /* Push pending writes */
 500         if (hp->n_outbuf > 0)
 501                 hvc_push(hp);
 502
 503         while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
 504                 if (rsize > count)
 505                         rsize = count;
 506                 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
 507                 count -= rsize;
 508                 buf += rsize;
 509                 hp->n_outbuf += rsize;
 510                 written += rsize;
 511                 hvc_push(hp);
 512         }
 513         spin_unlock_irqrestore(&hp->lock, flags);
 514
 515         /*
 516          * Racy, but harmless, kick thread if there is still pending data.
 517          */
 518         if (hp->n_outbuf)
 519                 hvc_kick();
 520
 521         return written;
 522 }
 523
 524 /**
 525  * hvc_set_winsz() - Resize the hvc tty terminal window.
 526  * @work:       work structure.
 527  *
 528  * The routine shall not be called within an atomic context because it
 529  * might sleep.
 530  *
 531  * Locking:     hp->lock
 532  */
 533 static void hvc_set_winsz(struct work_struct *work)
 534 {
 535         struct hvc_struct *hp;
 536         unsigned long hvc_flags;
 537         struct tty_struct *tty;
 538         struct winsize ws;
 539
 540         hp = container_of(work, struct hvc_struct, tty_resize);
 541
 542         tty = tty_port_tty_get(&hp->port);
 543         if (!tty)
 544                 return;
 545
 546         spin_lock_irqsave(&hp->lock, hvc_flags);
 547         ws = hp->ws;
 548         spin_unlock_irqrestore(&hp->lock, hvc_flags);
 549
 550         tty_do_resize(tty, &ws);
 551         tty_kref_put(tty);
 552 }
 553
 554 /*
 555  * This is actually a contract between the driver and the tty layer outlining
 556  * how much write room the driver can guarantee will be sent OR BUFFERED.  This
 557  * driver MUST honor the return value.
 558  */
 559 static int hvc_write_room(struct tty_struct *tty)
 560 {
 561         struct hvc_struct *hp = tty->driver_data;
 562
 563         if (!hp)
 564                 return 0;
 565
 566         return hp->outbuf_size - hp->n_outbuf;
 567 }
 568
 569 static int hvc_chars_in_buffer(struct tty_struct *tty)
 570 {
 571         struct hvc_struct *hp = tty->driver_data;
 572
 573         if (!hp)
 574                 return 0;
 575         return hp->n_outbuf;
 576 }
 577
 578 /*
 579  * timeout will vary between the MIN and MAX values defined here.  By default
 580  * and during console activity we will use a default MIN_TIMEOUT of 10.  When
 581  * the console is idle, we increase the timeout value on each pass through
 582  * msleep until we reach the max.  This may be noticeable as a brief (average
 583  * one second) delay on the console before the console responds to input when
 584  * there has been no input for some time.
 585  */
 586 #define MIN_TIMEOUT             (10)
 587 #define MAX_TIMEOUT             (2000)
 588 static u32 timeout = MIN_TIMEOUT;
 589
 590 #define HVC_POLL_READ   0x00000001
 591 #define HVC_POLL_WRITE  0x00000002
 592
 593 int hvc_poll(struct hvc_struct *hp)
 594 {
 595         struct tty_struct *tty;
 596         int i, n, poll_mask = 0;
 597         char buf[N_INBUF] __ALIGNED__;
 598         unsigned long flags;
 599         int read_total = 0;
 600         int written_total = 0;
 601
 602         spin_lock_irqsave(&hp->lock, flags);
 603
 604         /* Push pending writes */
 605         if (hp->n_outbuf > 0)
 606                 written_total = hvc_push(hp);
 607
 608         /* Reschedule us if still some write pending */
 609         if (hp->n_outbuf > 0) {
 610                 poll_mask |= HVC_POLL_WRITE;
 611                 /* If hvc_push() was not able to write, sleep a few msecs */
 612                 timeout = (written_total) ? 0 : MIN_TIMEOUT;
 613         }
 614
 615         /* No tty attached, just skip */
 616         tty = tty_port_tty_get(&hp->port);
 617         if (tty == NULL)
 618                 goto bail;
 619
 620         /* Now check if we can get data (are we throttled ?) */
 621         if (tty_throttled(tty))
 622                 goto throttled;
 623
 624         /* If we aren't notifier driven and aren't throttled, we always
 625          * request a reschedule
 626          */
 627         if (!hp->irq_requested)
 628                 poll_mask |= HVC_POLL_READ;
 629
 630         /* Read data if any */
 631         for (;;) {
 632                 int count = tty_buffer_request_room(&hp->port, N_INBUF);
 633
 634                 /* If flip is full, just reschedule a later read */
 635                 if (count == 0) {
 636                         poll_mask |= HVC_POLL_READ;
 637                         break;
 638                 }
 639
 640                 n = hp->ops->get_chars(hp->vtermno, buf, count);
 641                 if (n <= 0) {
 642                         /* Hangup the tty when disconnected from host */
 643                         if (n == -EPIPE) {
 644                                 spin_unlock_irqrestore(&hp->lock, flags);
 645                                 tty_hangup(tty);
 646                                 spin_lock_irqsave(&hp->lock, flags);
 647                         } else if ( n == -EAGAIN ) {
 648                                 /*
 649                                  * Some back-ends can only ensure a certain min
 650                                  * num of bytes read, which may be > 'count'.
 651                                  * Let the tty clear the flip buff to make room.
 652                                  */
 653                                 poll_mask |= HVC_POLL_READ;
 654                         }
 655                         break;
 656                 }
 657                 for (i = 0; i < n; ++i) {
 658 #ifdef CONFIG_MAGIC_SYSRQ
 659                         if (hp->index == hvc_console.index) {
 660                                 /* Handle the SysRq Hack */
 661                                 /* XXX should support a sequence */
 662                                 if (buf[i] == '\x0f') { /* ^O */
 663                                         /* if ^O is pressed again, reset
 664                                          * sysrq_pressed and flip ^O char */
 665                                         sysrq_pressed = !sysrq_pressed;
 666                                         if (sysrq_pressed)
 667                                                 continue;
 668                                 } else if (sysrq_pressed) {
 669                                         handle_sysrq(buf[i]);
 670                                         sysrq_pressed = 0;
 671                                         continue;
 672                                 }
 673                         }
 674 #endif /* CONFIG_MAGIC_SYSRQ */
 675                         tty_insert_flip_char(&hp->port, buf[i], 0);
 676                 }
 677
 678                 read_total += n;
 679         }
 680  throttled:
 681         /* Wakeup write queue if necessary */
 682         if (hp->do_wakeup) {
 683                 hp->do_wakeup = 0;
 684                 tty_wakeup(tty);
 685         }
 686  bail:
 687         spin_unlock_irqrestore(&hp->lock, flags);
 688
 689         if (read_total) {
 690                 /* Activity is occurring, so reset the polling backoff value to
 691                    a minimum for performance. */
 692                 timeout = MIN_TIMEOUT;
 693
 694                 tty_flip_buffer_push(&hp->port);
 695         }
 696         tty_kref_put(tty);
 697
 698         return poll_mask;
 699 }
 700 EXPORT_SYMBOL_GPL(hvc_poll);
 701
 702 /**
 703  * __hvc_resize() - Update terminal window size information.
 704  * @hp:         HVC console pointer
 705  * @ws:         Terminal window size structure
 706  *
 707  * Stores the specified window size information in the hvc structure of @hp.
 708  * The function schedule the tty resize update.
 709  *
 710  * Locking:     Locking free; the function MUST be called holding hp->lock
 711  */
 712 void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
 713 {
 714         hp->ws = ws;
 715         schedule_work(&hp->tty_resize);
 716 }
 717 EXPORT_SYMBOL_GPL(__hvc_resize);
 718
 719 /*
 720  * This kthread is either polling or interrupt driven.  This is determined by
 721  * calling hvc_poll() who determines whether a console adapter support
 722  * interrupts.
 723  */
 724 static int khvcd(void *unused)
 725 {
 726         int poll_mask;
 727         struct hvc_struct *hp;
 728
 729         set_freezable();
 730         do {
 731                 poll_mask = 0;
 732                 hvc_kicked = 0;
 733                 try_to_freeze();
 734                 wmb();
 735                 if (!cpus_are_in_xmon()) {
 736                         spin_lock(&hvc_structs_lock);
 737                         list_for_each_entry(hp, &hvc_structs, next) {
 738                                 poll_mask |= hvc_poll(hp);
 739                         }
 740                         spin_unlock(&hvc_structs_lock);
 741                 } else
 742                         poll_mask |= HVC_POLL_READ;
 743                 if (hvc_kicked)
 744                         continue;
 745                 set_current_state(TASK_INTERRUPTIBLE);
 746                 if (!hvc_kicked) {
 747                         if (poll_mask == 0)
 748                                 schedule();
 749                         else {
 750                                 unsigned long j_timeout;
 751
 752                                 if (timeout < MAX_TIMEOUT)
 753                                         timeout += (timeout >> 6) + 1;
 754
 755                                 /*
 756                                  * We don't use msleep_interruptible otherwise
 757                                  * "kick" will fail to wake us up
 758                                  */
 759                                 j_timeout = msecs_to_jiffies(timeout) + 1;
 760                                 schedule_timeout_interruptible(j_timeout);
 761                         }
 762                 }
 763                 __set_current_state(TASK_RUNNING);
 764         } while (!kthread_should_stop());
 765
 766         return 0;
 767 }
 768
 769 static int hvc_tiocmget(struct tty_struct *tty)
 770 {
 771         struct hvc_struct *hp = tty->driver_data;
 772
 773         if (!hp || !hp->ops->tiocmget)
 774                 return -EINVAL;
 775         return hp->ops->tiocmget(hp);
 776 }
 777
 778 static int hvc_tiocmset(struct tty_struct *tty,
 779                         unsigned int set, unsigned int clear)
 780 {
 781         struct hvc_struct *hp = tty->driver_data;
 782
 783         if (!hp || !hp->ops->tiocmset)
 784                 return -EINVAL;
 785         return hp->ops->tiocmset(hp, set, clear);
 786 }
 787
 788 #ifdef CONFIG_CONSOLE_POLL
 789 static int hvc_poll_init(struct tty_driver *driver, int line, char *options)
 790 {
 791         return 0;
 792 }
 793
 794 static int hvc_poll_get_char(struct tty_driver *driver, int line)
 795 {
 796         struct tty_struct *tty = driver->ttys[0];
 797         struct hvc_struct *hp = tty->driver_data;
 798         int n;
 799         char ch;
 800
 801         n = hp->ops->get_chars(hp->vtermno, &ch, 1);
 802
 803         if (n <= 0)
 804                 return NO_POLL_CHAR;
 805
 806         return ch;
 807 }
 808
 809 static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
 810 {
 811         struct tty_struct *tty = driver->ttys[0];
 812         struct hvc_struct *hp = tty->driver_data;
 813         int n;
 814
 815         do {
 816                 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
 817         } while (n <= 0);
 818 }
 819 #endif
 820
 821 static const struct tty_operations hvc_ops = {
 822         .install = hvc_install,
 823         .open = hvc_open,
 824         .close = hvc_close,
 825         .cleanup = hvc_cleanup,
 826         .write = hvc_write,
 827         .hangup = hvc_hangup,
 828         .unthrottle = hvc_unthrottle,
 829         .write_room = hvc_write_room,
 830         .chars_in_buffer = hvc_chars_in_buffer,
 831         .tiocmget = hvc_tiocmget,
 832         .tiocmset = hvc_tiocmset,
 833 #ifdef CONFIG_CONSOLE_POLL
 834         .poll_init = hvc_poll_init,
 835         .poll_get_char = hvc_poll_get_char,
 836         .poll_put_char = hvc_poll_put_char,
 837 #endif
 838 };
 839
 840 static const struct tty_port_operations hvc_port_ops = {
 841         .destruct = hvc_port_destruct,
 842 };
 843
 844 struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
 845                              const struct hv_ops *ops,
 846                              int outbuf_size)
 847 {
 848         struct hvc_struct *hp;
 849         int i;
 850
 851         /* We wait until a driver actually comes along */
 852         if (atomic_inc_not_zero(&hvc_needs_init)) {
 853                 int err = hvc_init();
 854                 if (err)
 855                         return ERR_PTR(err);
 856         }
 857
 858         hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
 859                         GFP_KERNEL);
 860         if (!hp)
 861                 return ERR_PTR(-ENOMEM);
 862
 863         hp->vtermno = vtermno;
 864         hp->data = data;
 865         hp->ops = ops;
 866         hp->outbuf_size = outbuf_size;
 867         hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
 868
 869         tty_port_init(&hp->port);
 870         hp->port.ops = &hvc_port_ops;
 871
 872         INIT_WORK(&hp->tty_resize, hvc_set_winsz);
 873         spin_lock_init(&hp->lock);
 874         spin_lock(&hvc_structs_lock);
 875
 876         /*
 877          * find index to use:
 878          * see if this vterm id matches one registered for console.
 879          */
 880         for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
 881                 if (vtermnos[i] == hp->vtermno &&
 882                     cons_ops[i] == hp->ops)
 883                         break;
 884
 885         /* no matching slot, just use a counter */
 886         if (i >= MAX_NR_HVC_CONSOLES)
 887                 i = ++last_hvc;
 888
 889         hp->index = i;
 890         cons_ops[i] = ops;
 891         vtermnos[i] = vtermno;
 892
 893         list_add_tail(&(hp->next), &hvc_structs);
 894         spin_unlock(&hvc_structs_lock);
 895
 896         /* check if we need to re-register the kernel console */
 897         hvc_check_console(i);
 898
 899         return hp;
 900 }
 901 EXPORT_SYMBOL_GPL(hvc_alloc);
 902
 903 int hvc_remove(struct hvc_struct *hp)
 904 {
 905         unsigned long flags;
 906         struct tty_struct *tty;
 907
 908         tty = tty_port_tty_get(&hp->port);
 909
 910         console_lock();
 911         spin_lock_irqsave(&hp->lock, flags);
 912         if (hp->index < MAX_NR_HVC_CONSOLES) {
 913                 vtermnos[hp->index] = -1;
 914                 cons_ops[hp->index] = NULL;
 915         }
 916
 917         /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
 918
 919         spin_unlock_irqrestore(&hp->lock, flags);
 920         console_unlock();
 921
 922         /*
 923          * We 'put' the instance that was grabbed when the kref instance
 924          * was initialized using kref_init().  Let the last holder of this
 925          * kref cause it to be removed, which will probably be the tty_vhangup
 926          * below.
 927          */
 928         tty_port_put(&hp->port);
 929
 930         /*
 931          * This function call will auto chain call hvc_hangup.
 932          */
 933         if (tty) {
 934                 tty_vhangup(tty);
 935                 tty_kref_put(tty);
 936         }
 937         return 0;
 938 }
 939 EXPORT_SYMBOL_GPL(hvc_remove);
 940
 941 /* Driver initialization: called as soon as someone uses hvc_alloc(). */
 942 static int hvc_init(void)
 943 {
 944         struct tty_driver *drv;
 945         int err;
 946
 947         /* We need more than hvc_count adapters due to hotplug additions. */
 948         drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
 949         if (!drv) {
 950                 err = -ENOMEM;
 951                 goto out;
 952         }
 953
 954         drv->driver_name = "hvc";
 955         drv->name = "hvc";
 956         drv->major = HVC_MAJOR;
 957         drv->minor_start = HVC_MINOR;
 958         drv->type = TTY_DRIVER_TYPE_SYSTEM;
 959         drv->init_termios = tty_std_termios;
 960         drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
 961         tty_set_operations(drv, &hvc_ops);
 962
 963         /* Always start the kthread because there can be hotplug vty adapters
 964          * added later. */
 965         hvc_task = kthread_run(khvcd, NULL, "khvcd");
 966         if (IS_ERR(hvc_task)) {
 967                 printk(KERN_ERR "Couldn't create kthread for console.\n");
 968                 err = PTR_ERR(hvc_task);
 969                 goto put_tty;
 970         }
 971
 972         err = tty_register_driver(drv);
 973         if (err) {
 974                 printk(KERN_ERR "Couldn't register hvc console driver\n");
 975                 goto stop_thread;
 976         }
 977
 978         /*
 979          * Make sure tty is fully registered before allowing it to be
 980          * found by hvc_console_device.
 981          */
 982         smp_mb();
 983         hvc_driver = drv;
 984         return 0;
 985
 986 stop_thread:
 987         kthread_stop(hvc_task);
 988         hvc_task = NULL;
 989 put_tty:
 990         put_tty_driver(drv);
 991 out:
 992         return err;
 993 }