git.oblomov.eu Git - linux-2.6/blob - drivers/char/hvc_console.c

   1 /*
   2  * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
   3  * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
   4  * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
   5  * Copyright (C) 2004 IBM Corporation
   6  *
   7  * Additional Author(s):
   8  *  Ryan S. Arnold <rsa@us.ibm.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  23  */
  24
  25 #include <linux/config.h>
  26 #include <linux/console.h>
  27 #include <linux/cpumask.h>
  28 #include <linux/init.h>
  29 #include <linux/kbd_kern.h>
  30 #include <linux/kernel.h>
  31 #include <linux/kobject.h>
  32 #include <linux/kthread.h>
  33 #include <linux/list.h>
  34 #include <linux/module.h>
  35 #include <linux/major.h>
  36 #include <linux/sysrq.h>
  37 #include <linux/tty.h>
  38 #include <linux/tty_flip.h>
  39 #include <linux/sched.h>
  40 #include <linux/spinlock.h>
  41 #include <linux/delay.h>
  42 #include <asm/uaccess.h>
  43 #include <asm/hvconsole.h>
  44 #include <asm/vio.h>
  45
  46 #define HVC_MAJOR       229
  47 #define HVC_MINOR       0
  48
  49 #define TIMEOUT         (10)
  50
  51 /*
  52  * Wait this long per iteration while trying to push buffered data to the
  53  * hypervisor before allowing the tty to complete a close operation.
  54  */
  55 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
  56
  57 /*
  58  * The Linux TTY code does not support dynamic addition of tty derived devices
  59  * so we need to know how many tty devices we might need when space is allocated
  60  * for the tty device.  Since this driver supports hotplug of vty adapters we
  61  * need to make sure we have enough allocated.
  62  */
  63 #define HVC_ALLOC_TTY_ADAPTERS  8
  64
  65 #define N_OUTBUF        16
  66 #define N_INBUF         16
  67
  68 #define __ALIGNED__     __attribute__((__aligned__(8)))
  69
  70 static struct tty_driver *hvc_driver;
  71 static struct task_struct *hvc_task;
  72
  73 /* Picks up late kicks after list walk but before schedule() */
  74 static int hvc_kicked;
  75
  76 #ifdef CONFIG_MAGIC_SYSRQ
  77 static int sysrq_pressed;
  78 #endif
  79
  80 struct hvc_struct {
  81         spinlock_t lock;
  82         int index;
  83         struct tty_struct *tty;
  84         unsigned int count;
  85         int do_wakeup;
  86         char outbuf[N_OUTBUF] __ALIGNED__;
  87         int n_outbuf;
  88         uint32_t vtermno;
  89         int irq_requested;
  90         int irq;
  91         struct list_head next;
  92         struct kobject kobj; /* ref count & hvc_struct lifetime */
  93         struct vio_dev *vdev;
  94 };
  95
  96 /* dynamic list of hvc_struct instances */
  97 static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs);
  98
  99 /*
 100  * Protect the list of hvc_struct instances from inserts and removals during
 101  * list traversal.
 102  */
 103 static DEFINE_SPINLOCK(hvc_structs_lock);
 104
 105 /*
 106  * This value is used to assign a tty->index value to a hvc_struct based
 107  * upon order of exposure via hvc_probe(), when we can not match it to
 108  * a console canidate registered with hvc_instantiate().
 109  */
 110 static int last_hvc = -1;
 111
 112 /*
 113  * Do not call this function with either the hvc_strucst_lock or the hvc_struct
 114  * lock held.  If successful, this function increments the kobject reference
 115  * count against the target hvc_struct so it should be released when finished.
 116  */
 117 struct hvc_struct *hvc_get_by_index(int index)
 118 {
 119         struct hvc_struct *hp;
 120         unsigned long flags;
 121
 122         spin_lock(&hvc_structs_lock);
 123
 124         list_for_each_entry(hp, &hvc_structs, next) {
 125                 spin_lock_irqsave(&hp->lock, flags);
 126                 if (hp->index == index) {
 127                         kobject_get(&hp->kobj);
 128                         spin_unlock_irqrestore(&hp->lock, flags);
 129                         spin_unlock(&hvc_structs_lock);
 130                         return hp;
 131                 }
 132                 spin_unlock_irqrestore(&hp->lock, flags);
 133         }
 134         hp = NULL;
 135
 136         spin_unlock(&hvc_structs_lock);
 137         return hp;
 138 }
 139
 140
 141 /*
 142  * Initial console vtermnos for console API usage prior to full console
 143  * initialization.  Any vty adapter outside this range will not have usable
 144  * console interfaces but can still be used as a tty device.  This has to be
 145  * static because kmalloc will not work during early console init.
 146  */
 147 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
 148         {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
 149
 150 /*
 151  * Console APIs, NOT TTY.  These APIs are available immediately when
 152  * hvc_console_setup() finds adapters.
 153  */
 154
 155 void hvc_console_print(struct console *co, const char *b, unsigned count)
 156 {
 157         char c[16] __ALIGNED__;
 158         unsigned i = 0, n = 0;
 159         int r, donecr = 0;
 160
 161         /* Console access attempt outside of acceptable console range. */
 162         if (co->index >= MAX_NR_HVC_CONSOLES)
 163                 return;
 164
 165         /* This console adapter was removed so it is not useable. */
 166         if (vtermnos[co->index] < 0)
 167                 return;
 168
 169         while (count > 0 || i > 0) {
 170                 if (count > 0 && i < sizeof(c)) {
 171                         if (b[n] == '\n' && !donecr) {
 172                                 c[i++] = '\r';
 173                                 donecr = 1;
 174                         } else {
 175                                 c[i++] = b[n++];
 176                                 donecr = 0;
 177                                 --count;
 178                         }
 179                 } else {
 180                         r = hvc_put_chars(vtermnos[co->index], c, i);
 181                         if (r < 0) {
 182                                 /* throw away chars on error */
 183                                 i = 0;
 184                         } else if (r > 0) {
 185                                 i -= r;
 186                                 if (i > 0)
 187                                         memmove(c, c+r, i);
 188                         }
 189                 }
 190         }
 191 }
 192
 193 static struct tty_driver *hvc_console_device(struct console *c, int *index)
 194 {
 195         *index = c->index;
 196         return hvc_driver;
 197 }
 198
 199 static int __init hvc_console_setup(struct console *co, char *options)
 200 {
 201         return 0;
 202 }
 203
 204 struct console hvc_con_driver = {
 205         .name           = "hvc",
 206         .write          = hvc_console_print,
 207         .device         = hvc_console_device,
 208         .setup          = hvc_console_setup,
 209         .flags          = CON_PRINTBUFFER,
 210         .index          = -1,
 211 };
 212
 213 /* Early console initialization.  Preceeds driver initialization. */
 214 static int __init hvc_console_init(void)
 215 {
 216         hvc_find_vtys();
 217         register_console(&hvc_con_driver);
 218         return 0;
 219 }
 220 console_initcall(hvc_console_init);
 221
 222 /*
 223  * hvc_instantiate() is an early console discovery method which locates
 224  * consoles * prior to the vio subsystem discovering them.  Hotplugged
 225  * vty adapters do NOT get an hvc_instantiate() callback since they
 226  * appear after early console init.
 227  */
 228 int hvc_instantiate(uint32_t vtermno, int index)
 229 {
 230         if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
 231                 return -1;
 232
 233         if (vtermnos[index] != -1)
 234                 return -1;
 235
 236         vtermnos[index] = vtermno;
 237
 238         /* reserve all indices upto and including this index */
 239         if (last_hvc < index)
 240                 last_hvc = index;
 241
 242         return 0;
 243 }
 244
 245 /* Wake the sleeping khvcd */
 246 static void hvc_kick(void)
 247 {
 248         hvc_kicked = 1;
 249         wake_up_process(hvc_task);
 250 }
 251
 252 static int hvc_poll(struct hvc_struct *hp);
 253
 254 /*
 255  * NOTE: This API isn't used if the console adapter doesn't support interrupts.
 256  * In this case the console is poll driven.
 257  */
 258 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
 259 {
 260         /* if hvc_poll request a repoll, then kick the hvcd thread */
 261         if (hvc_poll(dev_instance))
 262                 hvc_kick();
 263         return IRQ_HANDLED;
 264 }
 265
 266 static void hvc_unthrottle(struct tty_struct *tty)
 267 {
 268         hvc_kick();
 269 }
 270
 271 /*
 272  * The TTY interface won't be used until after the vio layer has exposed the vty
 273  * adapter to the kernel.
 274  */
 275 static int hvc_open(struct tty_struct *tty, struct file * filp)
 276 {
 277         struct hvc_struct *hp;
 278         unsigned long flags;
 279         int irq = NO_IRQ;
 280         int rc = 0;
 281         struct kobject *kobjp;
 282
 283         /* Auto increments kobject reference if found. */
 284         if (!(hp = hvc_get_by_index(tty->index))) {
 285                 printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
 286                 return -ENODEV;
 287         }
 288
 289         spin_lock_irqsave(&hp->lock, flags);
 290         /* Check and then increment for fast path open. */
 291         if (hp->count++ > 0) {
 292                 spin_unlock_irqrestore(&hp->lock, flags);
 293                 hvc_kick();
 294                 return 0;
 295         } /* else count == 0 */
 296
 297         tty->driver_data = hp;
 298         hp->tty = tty;
 299         /* Save for request_irq outside of spin_lock. */
 300         irq = hp->irq;
 301         if (irq != NO_IRQ)
 302                 hp->irq_requested = 1;
 303
 304         kobjp = &hp->kobj;
 305
 306         spin_unlock_irqrestore(&hp->lock, flags);
 307         /* check error, fallback to non-irq */
 308         if (irq != NO_IRQ)
 309                 rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp);
 310
 311         /*
 312          * If the request_irq() fails and we return an error.  The tty layer
 313          * will call hvc_close() after a failed open but we don't want to clean
 314          * up there so we'll clean up here and clear out the previously set
 315          * tty fields and return the kobject reference.
 316          */
 317         if (rc) {
 318                 spin_lock_irqsave(&hp->lock, flags);
 319                 hp->tty = NULL;
 320                 hp->irq_requested = 0;
 321                 spin_unlock_irqrestore(&hp->lock, flags);
 322                 tty->driver_data = NULL;
 323                 kobject_put(kobjp);
 324                 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
 325         }
 326         /* Force wakeup of the polling thread */
 327         hvc_kick();
 328
 329         return rc;
 330 }
 331
 332 static void hvc_close(struct tty_struct *tty, struct file * filp)
 333 {
 334         struct hvc_struct *hp;
 335         struct kobject *kobjp;
 336         int irq = NO_IRQ;
 337         unsigned long flags;
 338
 339         if (tty_hung_up_p(filp))
 340                 return;
 341
 342         /*
 343          * No driver_data means that this close was issued after a failed
 344          * hvc_open by the tty layer's release_dev() function and we can just
 345          * exit cleanly because the kobject reference wasn't made.
 346          */
 347         if (!tty->driver_data)
 348                 return;
 349
 350         hp = tty->driver_data;
 351         spin_lock_irqsave(&hp->lock, flags);
 352
 353         kobjp = &hp->kobj;
 354         if (--hp->count == 0) {
 355                 if (hp->irq_requested)
 356                         irq = hp->irq;
 357                 hp->irq_requested = 0;
 358
 359                 /* We are done with the tty pointer now. */
 360                 hp->tty = NULL;
 361                 spin_unlock_irqrestore(&hp->lock, flags);
 362
 363                 /*
 364                  * Chain calls chars_in_buffer() and returns immediately if
 365                  * there is no buffered data otherwise sleeps on a wait queue
 366                  * waking periodically to check chars_in_buffer().
 367                  */
 368                 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
 369
 370                 if (irq != NO_IRQ)
 371                         free_irq(irq, hp);
 372
 373         } else {
 374                 if (hp->count < 0)
 375                         printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
 376                                 hp->vtermno, hp->count);
 377                 spin_unlock_irqrestore(&hp->lock, flags);
 378         }
 379
 380         kobject_put(kobjp);
 381 }
 382
 383 static void hvc_hangup(struct tty_struct *tty)
 384 {
 385         struct hvc_struct *hp = tty->driver_data;
 386         unsigned long flags;
 387         int irq = NO_IRQ;
 388         int temp_open_count;
 389         struct kobject *kobjp;
 390
 391         if (!hp)
 392                 return;
 393
 394         spin_lock_irqsave(&hp->lock, flags);
 395
 396         /*
 397          * The N_TTY line discipline has problems such that in a close vs
 398          * open->hangup case this can be called after the final close so prevent
 399          * that from happening for now.
 400          */
 401         if (hp->count <= 0) {
 402                 spin_unlock_irqrestore(&hp->lock, flags);
 403                 return;
 404         }
 405
 406         kobjp = &hp->kobj;
 407         temp_open_count = hp->count;
 408         hp->count = 0;
 409         hp->n_outbuf = 0;
 410         hp->tty = NULL;
 411         if (hp->irq_requested)
 412                 /* Saved for use outside of spin_lock. */
 413                 irq = hp->irq;
 414         hp->irq_requested = 0;
 415         spin_unlock_irqrestore(&hp->lock, flags);
 416         if (irq != NO_IRQ)
 417                 free_irq(irq, hp);
 418         while(temp_open_count) {
 419                 --temp_open_count;
 420                 kobject_put(kobjp);
 421         }
 422 }
 423
 424 /*
 425  * Push buffered characters whether they were just recently buffered or waiting
 426  * on a blocked hypervisor.  Call this function with hp->lock held.
 427  */
 428 static void hvc_push(struct hvc_struct *hp)
 429 {
 430         int n;
 431
 432         n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
 433         if (n <= 0) {
 434                 if (n == 0)
 435                         return;
 436                 /* throw away output on error; this happens when
 437                    there is no session connected to the vterm. */
 438                 hp->n_outbuf = 0;
 439         } else
 440                 hp->n_outbuf -= n;
 441         if (hp->n_outbuf > 0)
 442                 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
 443         else
 444                 hp->do_wakeup = 1;
 445 }
 446
 447 static inline int __hvc_write_kernel(struct hvc_struct *hp,
 448                                    const unsigned char *buf, int count)
 449 {
 450         unsigned long flags;
 451         int rsize, written = 0;
 452
 453         spin_lock_irqsave(&hp->lock, flags);
 454
 455         /* Push pending writes */
 456         if (hp->n_outbuf > 0)
 457                 hvc_push(hp);
 458
 459         while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
 460                 if (rsize > count)
 461                         rsize = count;
 462                 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
 463                 count -= rsize;
 464                 buf += rsize;
 465                 hp->n_outbuf += rsize;
 466                 written += rsize;
 467                 hvc_push(hp);
 468         }
 469         spin_unlock_irqrestore(&hp->lock, flags);
 470
 471         return written;
 472 }
 473 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
 474 {
 475         struct hvc_struct *hp = tty->driver_data;
 476         int written;
 477
 478         /* This write was probably executed during a tty close. */
 479         if (!hp)
 480                 return -EPIPE;
 481
 482         if (hp->count <= 0)
 483                 return -EIO;
 484
 485         written = __hvc_write_kernel(hp, buf, count);
 486
 487         /*
 488          * Racy, but harmless, kick thread if there is still pending data.
 489          * There really is nothing wrong with kicking the thread, even if there
 490          * is no buffered data.
 491          */
 492         if (hp->n_outbuf)
 493                 hvc_kick();
 494
 495         return written;
 496 }
 497
 498 /*
 499  * This is actually a contract between the driver and the tty layer outlining
 500  * how much write room the driver can guarentee will be sent OR BUFFERED.  This
 501  * driver MUST honor the return value.
 502  */
 503 static int hvc_write_room(struct tty_struct *tty)
 504 {
 505         struct hvc_struct *hp = tty->driver_data;
 506
 507         if (!hp)
 508                 return -1;
 509
 510         return N_OUTBUF - hp->n_outbuf;
 511 }
 512
 513 static int hvc_chars_in_buffer(struct tty_struct *tty)
 514 {
 515         struct hvc_struct *hp = tty->driver_data;
 516
 517         if (!hp)
 518                 return -1;
 519         return hp->n_outbuf;
 520 }
 521
 522 #define HVC_POLL_READ   0x00000001
 523 #define HVC_POLL_WRITE  0x00000002
 524 #define HVC_POLL_QUICK  0x00000004
 525
 526 static int hvc_poll(struct hvc_struct *hp)
 527 {
 528         struct tty_struct *tty;
 529         int i, n, poll_mask = 0;
 530         char buf[N_INBUF] __ALIGNED__;
 531         unsigned long flags;
 532         int read_total = 0;
 533
 534         spin_lock_irqsave(&hp->lock, flags);
 535
 536         /* Push pending writes */
 537         if (hp->n_outbuf > 0)
 538                 hvc_push(hp);
 539         /* Reschedule us if still some write pending */
 540         if (hp->n_outbuf > 0)
 541                 poll_mask |= HVC_POLL_WRITE;
 542
 543         /* No tty attached, just skip */
 544         tty = hp->tty;
 545         if (tty == NULL)
 546                 goto bail;
 547
 548         /* Now check if we can get data (are we throttled ?) */
 549         if (test_bit(TTY_THROTTLED, &tty->flags))
 550                 goto throttled;
 551
 552         /* If we aren't interrupt driven and aren't throttled, we always
 553          * request a reschedule
 554          */
 555         if (hp->irq == NO_IRQ)
 556                 poll_mask |= HVC_POLL_READ;
 557
 558         /* Read data if any */
 559         for (;;) {
 560                 int count = N_INBUF;
 561                 if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
 562                         count = TTY_FLIPBUF_SIZE - tty->flip.count;
 563
 564                 /* If flip is full, just reschedule a later read */
 565                 if (count == 0) {
 566                         poll_mask |= HVC_POLL_READ;
 567                         break;
 568                 }
 569
 570                 n = hvc_get_chars(hp->vtermno, buf, count);
 571                 if (n <= 0) {
 572                         /* Hangup the tty when disconnected from host */
 573                         if (n == -EPIPE) {
 574                                 spin_unlock_irqrestore(&hp->lock, flags);
 575                                 tty_hangup(tty);
 576                                 spin_lock_irqsave(&hp->lock, flags);
 577                         }
 578                         break;
 579                 }
 580                 for (i = 0; i < n; ++i) {
 581 #ifdef CONFIG_MAGIC_SYSRQ
 582                         if (hp->index == hvc_con_driver.index) {
 583                                 /* Handle the SysRq Hack */
 584                                 /* XXX should support a sequence */
 585                                 if (buf[i] == '\x0f') { /* ^O */
 586                                         sysrq_pressed = 1;
 587                                         continue;
 588                                 } else if (sysrq_pressed) {
 589                                         handle_sysrq(buf[i], NULL, tty);
 590                                         sysrq_pressed = 0;
 591                                         continue;
 592                                 }
 593                         }
 594 #endif /* CONFIG_MAGIC_SYSRQ */
 595                         tty_insert_flip_char(tty, buf[i], 0);
 596                 }
 597
 598                 if (tty->flip.count)
 599                         tty_schedule_flip(tty);
 600
 601                 /*
 602                  * Account for the total amount read in one loop, and if above
 603                  * 64 bytes, we do a quick schedule loop to let the tty grok
 604                  * the data and eventually throttle us.
 605                  */
 606                 read_total += n;
 607                 if (read_total >= 64) {
 608                         poll_mask |= HVC_POLL_QUICK;
 609                         break;
 610                 }
 611         }
 612  throttled:
 613         /* Wakeup write queue if necessary */
 614         if (hp->do_wakeup) {
 615                 hp->do_wakeup = 0;
 616                 tty_wakeup(tty);
 617         }
 618  bail:
 619         spin_unlock_irqrestore(&hp->lock, flags);
 620
 621         return poll_mask;
 622 }
 623
 624 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
 625 extern cpumask_t cpus_in_xmon;
 626 #else
 627 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
 628 #endif
 629
 630 /*
 631  * This kthread is either polling or interrupt driven.  This is determined by
 632  * calling hvc_poll() who determines whether a console adapter support
 633  * interrupts.
 634  */
 635 int khvcd(void *unused)
 636 {
 637         int poll_mask;
 638         struct hvc_struct *hp;
 639
 640         __set_current_state(TASK_RUNNING);
 641         do {
 642                 poll_mask = 0;
 643                 hvc_kicked = 0;
 644                 wmb();
 645                 if (cpus_empty(cpus_in_xmon)) {
 646                         spin_lock(&hvc_structs_lock);
 647                         list_for_each_entry(hp, &hvc_structs, next) {
 648                                 poll_mask |= hvc_poll(hp);
 649                         }
 650                         spin_unlock(&hvc_structs_lock);
 651                 } else
 652                         poll_mask |= HVC_POLL_READ;
 653                 if (hvc_kicked)
 654                         continue;
 655                 if (poll_mask & HVC_POLL_QUICK) {
 656                         yield();
 657                         continue;
 658                 }
 659                 set_current_state(TASK_INTERRUPTIBLE);
 660                 if (!hvc_kicked) {
 661                         if (poll_mask == 0)
 662                                 schedule();
 663                         else
 664                                 msleep_interruptible(TIMEOUT);
 665                 }
 666                 __set_current_state(TASK_RUNNING);
 667         } while (!kthread_should_stop());
 668
 669         return 0;
 670 }
 671
 672 static struct tty_operations hvc_ops = {
 673         .open = hvc_open,
 674         .close = hvc_close,
 675         .write = hvc_write,
 676         .hangup = hvc_hangup,
 677         .unthrottle = hvc_unthrottle,
 678         .write_room = hvc_write_room,
 679         .chars_in_buffer = hvc_chars_in_buffer,
 680 };
 681
 682 /* callback when the kboject ref count reaches zero. */
 683 static void destroy_hvc_struct(struct kobject *kobj)
 684 {
 685         struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
 686         unsigned long flags;
 687
 688         spin_lock(&hvc_structs_lock);
 689
 690         spin_lock_irqsave(&hp->lock, flags);
 691         list_del(&(hp->next));
 692         spin_unlock_irqrestore(&hp->lock, flags);
 693
 694         spin_unlock(&hvc_structs_lock);
 695
 696         kfree(hp);
 697 }
 698
 699 static struct kobj_type hvc_kobj_type = {
 700         .release = destroy_hvc_struct,
 701 };
 702
 703 static int __devinit hvc_probe(
 704                 struct vio_dev *dev,
 705                 const struct vio_device_id *id)
 706 {
 707         struct hvc_struct *hp;
 708         int i;
 709
 710         /* probed with invalid parameters. */
 711         if (!dev || !id)
 712                 return -EPERM;
 713
 714         hp = kmalloc(sizeof(*hp), GFP_KERNEL);
 715         if (!hp)
 716                 return -ENOMEM;
 717
 718         memset(hp, 0x00, sizeof(*hp));
 719         hp->vtermno = dev->unit_address;
 720         hp->vdev = dev;
 721         hp->vdev->dev.driver_data = hp;
 722         hp->irq = dev->irq;
 723
 724         kobject_init(&hp->kobj);
 725         hp->kobj.ktype = &hvc_kobj_type;
 726
 727         spin_lock_init(&hp->lock);
 728         spin_lock(&hvc_structs_lock);
 729
 730         /*
 731          * find index to use:
 732          * see if this vterm id matches one registered for console.
 733          */
 734         for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
 735                 if (vtermnos[i] == hp->vtermno)
 736                         break;
 737
 738         /* no matching slot, just use a counter */
 739         if (i >= MAX_NR_HVC_CONSOLES)
 740                 i = ++last_hvc;
 741
 742         hp->index = i;
 743
 744         list_add_tail(&(hp->next), &hvc_structs);
 745         spin_unlock(&hvc_structs_lock);
 746
 747         return 0;
 748 }
 749
 750 static int __devexit hvc_remove(struct vio_dev *dev)
 751 {
 752         struct hvc_struct *hp = dev->dev.driver_data;
 753         unsigned long flags;
 754         struct kobject *kobjp;
 755         struct tty_struct *tty;
 756
 757         spin_lock_irqsave(&hp->lock, flags);
 758         tty = hp->tty;
 759         kobjp = &hp->kobj;
 760
 761         if (hp->index < MAX_NR_HVC_CONSOLES)
 762                 vtermnos[hp->index] = -1;
 763
 764         /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
 765
 766         spin_unlock_irqrestore(&hp->lock, flags);
 767
 768         /*
 769          * We 'put' the instance that was grabbed when the kobject instance
 770          * was intialized using kobject_init().  Let the last holder of this
 771          * kobject cause it to be removed, which will probably be the tty_hangup
 772          * below.
 773          */
 774         kobject_put(kobjp);
 775
 776         /*
 777          * This function call will auto chain call hvc_hangup.  The tty should
 778          * always be valid at this time unless a simultaneous tty close already
 779          * cleaned up the hvc_struct.
 780          */
 781         if (tty)
 782                 tty_hangup(tty);
 783         return 0;
 784 }
 785
 786 char hvc_driver_name[] = "hvc_console";
 787
 788 static struct vio_device_id hvc_driver_table[] __devinitdata= {
 789         {"serial", "hvterm1"},
 790         { NULL, }
 791 };
 792 MODULE_DEVICE_TABLE(vio, hvc_driver_table);
 793
 794 static struct vio_driver hvc_vio_driver = {
 795         .name           = hvc_driver_name,
 796         .id_table       = hvc_driver_table,
 797         .probe          = hvc_probe,
 798         .remove         = hvc_remove,
 799 };
 800
 801 /* Driver initialization.  Follow console initialization.  This is where the TTY
 802  * interfaces start to become available. */
 803 int __init hvc_init(void)
 804 {
 805         int rc;
 806
 807         /* We need more than hvc_count adapters due to hotplug additions. */
 808         hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
 809         if (!hvc_driver)
 810                 return -ENOMEM;
 811
 812         hvc_driver->owner = THIS_MODULE;
 813         hvc_driver->devfs_name = "hvc/";
 814         hvc_driver->driver_name = "hvc";
 815         hvc_driver->name = "hvc";
 816         hvc_driver->major = HVC_MAJOR;
 817         hvc_driver->minor_start = HVC_MINOR;
 818         hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
 819         hvc_driver->init_termios = tty_std_termios;
 820         hvc_driver->flags = TTY_DRIVER_REAL_RAW;
 821         tty_set_operations(hvc_driver, &hvc_ops);
 822
 823         if (tty_register_driver(hvc_driver))
 824                 panic("Couldn't register hvc console driver\n");
 825
 826         /* Always start the kthread because there can be hotplug vty adapters
 827          * added later. */
 828         hvc_task = kthread_run(khvcd, NULL, "khvcd");
 829         if (IS_ERR(hvc_task)) {
 830                 panic("Couldn't create kthread for console.\n");
 831                 put_tty_driver(hvc_driver);
 832                 return -EIO;
 833         }
 834
 835         /* Register as a vio device to receive callbacks */
 836         rc = vio_register_driver(&hvc_vio_driver);
 837
 838         return rc;
 839 }
 840 module_init(hvc_init);
 841
 842 /* This isn't particularily necessary due to this being a console driver
 843  * but it is nice to be thorough.
 844  */
 845 static void __exit hvc_exit(void)
 846 {
 847         kthread_stop(hvc_task);
 848
 849         vio_unregister_driver(&hvc_vio_driver);
 850         tty_unregister_driver(hvc_driver);
 851         /* return tty_struct instances allocated in hvc_init(). */
 852         put_tty_driver(hvc_driver);
 853         unregister_console(&hvc_con_driver);
 854 }
 855 module_exit(hvc_exit);