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
 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         int i;
 217
 218         for (i=0; i<MAX_NR_HVC_CONSOLES; i++)
 219                 vtermnos[i] = -1;
 220         hvc_find_vtys();
 221         register_console(&hvc_con_driver);
 222         return 0;
 223 }
 224 console_initcall(hvc_console_init);
 225
 226 /*
 227  * hvc_instantiate() is an early console discovery method which locates
 228  * consoles * prior to the vio subsystem discovering them.  Hotplugged
 229  * vty adapters do NOT get an hvc_instantiate() callback since they
 230  * appear after early console init.
 231  */
 232 int hvc_instantiate(uint32_t vtermno, int index)
 233 {
 234         if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
 235                 return -1;
 236
 237         if (vtermnos[index] != -1)
 238                 return -1;
 239
 240         vtermnos[index] = vtermno;
 241
 242         /* reserve all indices upto and including this index */
 243         if (last_hvc < index)
 244                 last_hvc = index;
 245
 246         return 0;
 247 }
 248
 249 /* Wake the sleeping khvcd */
 250 static void hvc_kick(void)
 251 {
 252         hvc_kicked = 1;
 253         wake_up_process(hvc_task);
 254 }
 255
 256 static int hvc_poll(struct hvc_struct *hp);
 257
 258 /*
 259  * NOTE: This API isn't used if the console adapter doesn't support interrupts.
 260  * In this case the console is poll driven.
 261  */
 262 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
 263 {
 264         /* if hvc_poll request a repoll, then kick the hvcd thread */
 265         if (hvc_poll(dev_instance))
 266                 hvc_kick();
 267         return IRQ_HANDLED;
 268 }
 269
 270 static void hvc_unthrottle(struct tty_struct *tty)
 271 {
 272         hvc_kick();
 273 }
 274
 275 /*
 276  * The TTY interface won't be used until after the vio layer has exposed the vty
 277  * adapter to the kernel.
 278  */
 279 static int hvc_open(struct tty_struct *tty, struct file * filp)
 280 {
 281         struct hvc_struct *hp;
 282         unsigned long flags;
 283         int irq = NO_IRQ;
 284         int rc = 0;
 285         struct kobject *kobjp;
 286
 287         /* Auto increments kobject reference if found. */
 288         if (!(hp = hvc_get_by_index(tty->index))) {
 289                 printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
 290                 return -ENODEV;
 291         }
 292
 293         spin_lock_irqsave(&hp->lock, flags);
 294         /* Check and then increment for fast path open. */
 295         if (hp->count++ > 0) {
 296                 spin_unlock_irqrestore(&hp->lock, flags);
 297                 hvc_kick();
 298                 return 0;
 299         } /* else count == 0 */
 300
 301         tty->driver_data = hp;
 302         hp->tty = tty;
 303         /* Save for request_irq outside of spin_lock. */
 304         irq = hp->irq;
 305         if (irq != NO_IRQ)
 306                 hp->irq_requested = 1;
 307
 308         kobjp = &hp->kobj;
 309
 310         spin_unlock_irqrestore(&hp->lock, flags);
 311         /* check error, fallback to non-irq */
 312         if (irq != NO_IRQ)
 313                 rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp);
 314
 315         /*
 316          * If the request_irq() fails and we return an error.  The tty layer
 317          * will call hvc_close() after a failed open but we don't want to clean
 318          * up there so we'll clean up here and clear out the previously set
 319          * tty fields and return the kobject reference.
 320          */
 321         if (rc) {
 322                 spin_lock_irqsave(&hp->lock, flags);
 323                 hp->tty = NULL;
 324                 hp->irq_requested = 0;
 325                 spin_unlock_irqrestore(&hp->lock, flags);
 326                 tty->driver_data = NULL;
 327                 kobject_put(kobjp);
 328                 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
 329         }
 330         /* Force wakeup of the polling thread */
 331         hvc_kick();
 332
 333         return rc;
 334 }
 335
 336 static void hvc_close(struct tty_struct *tty, struct file * filp)
 337 {
 338         struct hvc_struct *hp;
 339         struct kobject *kobjp;
 340         int irq = NO_IRQ;
 341         unsigned long flags;
 342
 343         if (tty_hung_up_p(filp))
 344                 return;
 345
 346         /*
 347          * No driver_data means that this close was issued after a failed
 348          * hvc_open by the tty layer's release_dev() function and we can just
 349          * exit cleanly because the kobject reference wasn't made.
 350          */
 351         if (!tty->driver_data)
 352                 return;
 353
 354         hp = tty->driver_data;
 355         spin_lock_irqsave(&hp->lock, flags);
 356
 357         kobjp = &hp->kobj;
 358         if (--hp->count == 0) {
 359                 if (hp->irq_requested)
 360                         irq = hp->irq;
 361                 hp->irq_requested = 0;
 362
 363                 /* We are done with the tty pointer now. */
 364                 hp->tty = NULL;
 365                 spin_unlock_irqrestore(&hp->lock, flags);
 366
 367                 /*
 368                  * Chain calls chars_in_buffer() and returns immediately if
 369                  * there is no buffered data otherwise sleeps on a wait queue
 370                  * waking periodically to check chars_in_buffer().
 371                  */
 372                 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
 373
 374                 if (irq != NO_IRQ)
 375                         free_irq(irq, hp);
 376
 377         } else {
 378                 if (hp->count < 0)
 379                         printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
 380                                 hp->vtermno, hp->count);
 381                 spin_unlock_irqrestore(&hp->lock, flags);
 382         }
 383
 384         kobject_put(kobjp);
 385 }
 386
 387 static void hvc_hangup(struct tty_struct *tty)
 388 {
 389         struct hvc_struct *hp = tty->driver_data;
 390         unsigned long flags;
 391         int irq = NO_IRQ;
 392         int temp_open_count;
 393         struct kobject *kobjp;
 394
 395         if (!hp)
 396                 return;
 397
 398         spin_lock_irqsave(&hp->lock, flags);
 399
 400         /*
 401          * The N_TTY line discipline has problems such that in a close vs
 402          * open->hangup case this can be called after the final close so prevent
 403          * that from happening for now.
 404          */
 405         if (hp->count <= 0) {
 406                 spin_unlock_irqrestore(&hp->lock, flags);
 407                 return;
 408         }
 409
 410         kobjp = &hp->kobj;
 411         temp_open_count = hp->count;
 412         hp->count = 0;
 413         hp->n_outbuf = 0;
 414         hp->tty = NULL;
 415         if (hp->irq_requested)
 416                 /* Saved for use outside of spin_lock. */
 417                 irq = hp->irq;
 418         hp->irq_requested = 0;
 419         spin_unlock_irqrestore(&hp->lock, flags);
 420         if (irq != NO_IRQ)
 421                 free_irq(irq, hp);
 422         while(temp_open_count) {
 423                 --temp_open_count;
 424                 kobject_put(kobjp);
 425         }
 426 }
 427
 428 /*
 429  * Push buffered characters whether they were just recently buffered or waiting
 430  * on a blocked hypervisor.  Call this function with hp->lock held.
 431  */
 432 static void hvc_push(struct hvc_struct *hp)
 433 {
 434         int n;
 435
 436         n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
 437         if (n <= 0) {
 438                 if (n == 0)
 439                         return;
 440                 /* throw away output on error; this happens when
 441                    there is no session connected to the vterm. */
 442                 hp->n_outbuf = 0;
 443         } else
 444                 hp->n_outbuf -= n;
 445         if (hp->n_outbuf > 0)
 446                 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
 447         else
 448                 hp->do_wakeup = 1;
 449 }
 450
 451 static inline int __hvc_write_kernel(struct hvc_struct *hp,
 452                                    const unsigned char *buf, int count)
 453 {
 454         unsigned long flags;
 455         int rsize, written = 0;
 456
 457         spin_lock_irqsave(&hp->lock, flags);
 458
 459         /* Push pending writes */
 460         if (hp->n_outbuf > 0)
 461                 hvc_push(hp);
 462
 463         while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
 464                 if (rsize > count)
 465                         rsize = count;
 466                 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
 467                 count -= rsize;
 468                 buf += rsize;
 469                 hp->n_outbuf += rsize;
 470                 written += rsize;
 471                 hvc_push(hp);
 472         }
 473         spin_unlock_irqrestore(&hp->lock, flags);
 474
 475         return written;
 476 }
 477 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
 478 {
 479         struct hvc_struct *hp = tty->driver_data;
 480         int written;
 481
 482         /* This write was probably executed during a tty close. */
 483         if (!hp)
 484                 return -EPIPE;
 485
 486         if (hp->count <= 0)
 487                 return -EIO;
 488
 489         written = __hvc_write_kernel(hp, buf, count);
 490
 491         /*
 492          * Racy, but harmless, kick thread if there is still pending data.
 493          * There really is nothing wrong with kicking the thread, even if there
 494          * is no buffered data.
 495          */
 496         if (hp->n_outbuf)
 497                 hvc_kick();
 498
 499         return written;
 500 }
 501
 502 /*
 503  * This is actually a contract between the driver and the tty layer outlining
 504  * how much write room the driver can guarentee will be sent OR BUFFERED.  This
 505  * driver MUST honor the return value.
 506  */
 507 static int hvc_write_room(struct tty_struct *tty)
 508 {
 509         struct hvc_struct *hp = tty->driver_data;
 510
 511         if (!hp)
 512                 return -1;
 513
 514         return N_OUTBUF - hp->n_outbuf;
 515 }
 516
 517 static int hvc_chars_in_buffer(struct tty_struct *tty)
 518 {
 519         struct hvc_struct *hp = tty->driver_data;
 520
 521         if (!hp)
 522                 return -1;
 523         return hp->n_outbuf;
 524 }
 525
 526 #define HVC_POLL_READ   0x00000001
 527 #define HVC_POLL_WRITE  0x00000002
 528 #define HVC_POLL_QUICK  0x00000004
 529
 530 static int hvc_poll(struct hvc_struct *hp)
 531 {
 532         struct tty_struct *tty;
 533         int i, n, poll_mask = 0;
 534         char buf[N_INBUF] __ALIGNED__;
 535         unsigned long flags;
 536         int read_total = 0;
 537
 538         spin_lock_irqsave(&hp->lock, flags);
 539
 540         /* Push pending writes */
 541         if (hp->n_outbuf > 0)
 542                 hvc_push(hp);
 543         /* Reschedule us if still some write pending */
 544         if (hp->n_outbuf > 0)
 545                 poll_mask |= HVC_POLL_WRITE;
 546
 547         /* No tty attached, just skip */
 548         tty = hp->tty;
 549         if (tty == NULL)
 550                 goto bail;
 551
 552         /* Now check if we can get data (are we throttled ?) */
 553         if (test_bit(TTY_THROTTLED, &tty->flags))
 554                 goto throttled;
 555
 556         /* If we aren't interrupt driven and aren't throttled, we always
 557          * request a reschedule
 558          */
 559         if (hp->irq == NO_IRQ)
 560                 poll_mask |= HVC_POLL_READ;
 561
 562         /* Read data if any */
 563         for (;;) {
 564                 int count = N_INBUF;
 565                 if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
 566                         count = TTY_FLIPBUF_SIZE - tty->flip.count;
 567
 568                 /* If flip is full, just reschedule a later read */
 569                 if (count == 0) {
 570                         poll_mask |= HVC_POLL_READ;
 571                         break;
 572                 }
 573
 574                 n = hvc_get_chars(hp->vtermno, buf, count);
 575                 if (n <= 0) {
 576                         /* Hangup the tty when disconnected from host */
 577                         if (n == -EPIPE) {
 578                                 spin_unlock_irqrestore(&hp->lock, flags);
 579                                 tty_hangup(tty);
 580                                 spin_lock_irqsave(&hp->lock, flags);
 581                         }
 582                         break;
 583                 }
 584                 for (i = 0; i < n; ++i) {
 585 #ifdef CONFIG_MAGIC_SYSRQ
 586                         if (hp->index == hvc_con_driver.index) {
 587                                 /* Handle the SysRq Hack */
 588                                 /* XXX should support a sequence */
 589                                 if (buf[i] == '\x0f') { /* ^O */
 590                                         sysrq_pressed = 1;
 591                                         continue;
 592                                 } else if (sysrq_pressed) {
 593                                         handle_sysrq(buf[i], NULL, tty);
 594                                         sysrq_pressed = 0;
 595                                         continue;
 596                                 }
 597                         }
 598 #endif /* CONFIG_MAGIC_SYSRQ */
 599                         tty_insert_flip_char(tty, buf[i], 0);
 600                 }
 601
 602                 if (tty->flip.count)
 603                         tty_schedule_flip(tty);
 604
 605                 /*
 606                  * Account for the total amount read in one loop, and if above
 607                  * 64 bytes, we do a quick schedule loop to let the tty grok
 608                  * the data and eventually throttle us.
 609                  */
 610                 read_total += n;
 611                 if (read_total >= 64) {
 612                         poll_mask |= HVC_POLL_QUICK;
 613                         break;
 614                 }
 615         }
 616  throttled:
 617         /* Wakeup write queue if necessary */
 618         if (hp->do_wakeup) {
 619                 hp->do_wakeup = 0;
 620                 tty_wakeup(tty);
 621         }
 622  bail:
 623         spin_unlock_irqrestore(&hp->lock, flags);
 624
 625         return poll_mask;
 626 }
 627
 628 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
 629 extern cpumask_t cpus_in_xmon;
 630 #else
 631 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
 632 #endif
 633
 634 /*
 635  * This kthread is either polling or interrupt driven.  This is determined by
 636  * calling hvc_poll() who determines whether a console adapter support
 637  * interrupts.
 638  */
 639 int khvcd(void *unused)
 640 {
 641         int poll_mask;
 642         struct hvc_struct *hp;
 643
 644         __set_current_state(TASK_RUNNING);
 645         do {
 646                 poll_mask = 0;
 647                 hvc_kicked = 0;
 648                 wmb();
 649                 if (cpus_empty(cpus_in_xmon)) {
 650                         spin_lock(&hvc_structs_lock);
 651                         list_for_each_entry(hp, &hvc_structs, next) {
 652                                 poll_mask |= hvc_poll(hp);
 653                         }
 654                         spin_unlock(&hvc_structs_lock);
 655                 } else
 656                         poll_mask |= HVC_POLL_READ;
 657                 if (hvc_kicked)
 658                         continue;
 659                 if (poll_mask & HVC_POLL_QUICK) {
 660                         yield();
 661                         continue;
 662                 }
 663                 set_current_state(TASK_INTERRUPTIBLE);
 664                 if (!hvc_kicked) {
 665                         if (poll_mask == 0)
 666                                 schedule();
 667                         else
 668                                 msleep_interruptible(TIMEOUT);
 669                 }
 670                 __set_current_state(TASK_RUNNING);
 671         } while (!kthread_should_stop());
 672
 673         return 0;
 674 }
 675
 676 static struct tty_operations hvc_ops = {
 677         .open = hvc_open,
 678         .close = hvc_close,
 679         .write = hvc_write,
 680         .hangup = hvc_hangup,
 681         .unthrottle = hvc_unthrottle,
 682         .write_room = hvc_write_room,
 683         .chars_in_buffer = hvc_chars_in_buffer,
 684 };
 685
 686 /* callback when the kboject ref count reaches zero. */
 687 static void destroy_hvc_struct(struct kobject *kobj)
 688 {
 689         struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
 690         unsigned long flags;
 691
 692         spin_lock(&hvc_structs_lock);
 693
 694         spin_lock_irqsave(&hp->lock, flags);
 695         list_del(&(hp->next));
 696         spin_unlock_irqrestore(&hp->lock, flags);
 697
 698         spin_unlock(&hvc_structs_lock);
 699
 700         kfree(hp);
 701 }
 702
 703 static struct kobj_type hvc_kobj_type = {
 704         .release = destroy_hvc_struct,
 705 };
 706
 707 static int __devinit hvc_probe(
 708                 struct vio_dev *dev,
 709                 const struct vio_device_id *id)
 710 {
 711         struct hvc_struct *hp;
 712         int i;
 713
 714         /* probed with invalid parameters. */
 715         if (!dev || !id)
 716                 return -EPERM;
 717
 718         hp = kmalloc(sizeof(*hp), GFP_KERNEL);
 719         if (!hp)
 720                 return -ENOMEM;
 721
 722         memset(hp, 0x00, sizeof(*hp));
 723         hp->vtermno = dev->unit_address;
 724         hp->vdev = dev;
 725         hp->vdev->dev.driver_data = hp;
 726         hp->irq = dev->irq;
 727
 728         kobject_init(&hp->kobj);
 729         hp->kobj.ktype = &hvc_kobj_type;
 730
 731         spin_lock_init(&hp->lock);
 732         spin_lock(&hvc_structs_lock);
 733
 734         /*
 735          * find index to use:
 736          * see if this vterm id matches one registered for console.
 737          */
 738         for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
 739                 if (vtermnos[i] == hp->vtermno)
 740                         break;
 741
 742         /* no matching slot, just use a counter */
 743         if (i >= MAX_NR_HVC_CONSOLES)
 744                 i = ++last_hvc;
 745
 746         hp->index = i;
 747
 748         list_add_tail(&(hp->next), &hvc_structs);
 749         spin_unlock(&hvc_structs_lock);
 750
 751         return 0;
 752 }
 753
 754 static int __devexit hvc_remove(struct vio_dev *dev)
 755 {
 756         struct hvc_struct *hp = dev->dev.driver_data;
 757         unsigned long flags;
 758         struct kobject *kobjp;
 759         struct tty_struct *tty;
 760
 761         spin_lock_irqsave(&hp->lock, flags);
 762         tty = hp->tty;
 763         kobjp = &hp->kobj;
 764
 765         if (hp->index < MAX_NR_HVC_CONSOLES)
 766                 vtermnos[hp->index] = -1;
 767
 768         /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
 769
 770         spin_unlock_irqrestore(&hp->lock, flags);
 771
 772         /*
 773          * We 'put' the instance that was grabbed when the kobject instance
 774          * was intialized using kobject_init().  Let the last holder of this
 775          * kobject cause it to be removed, which will probably be the tty_hangup
 776          * below.
 777          */
 778         kobject_put(kobjp);
 779
 780         /*
 781          * This function call will auto chain call hvc_hangup.  The tty should
 782          * always be valid at this time unless a simultaneous tty close already
 783          * cleaned up the hvc_struct.
 784          */
 785         if (tty)
 786                 tty_hangup(tty);
 787         return 0;
 788 }
 789
 790 char hvc_driver_name[] = "hvc_console";
 791
 792 static struct vio_device_id hvc_driver_table[] __devinitdata= {
 793         {"serial", "hvterm1"},
 794         { NULL, }
 795 };
 796 MODULE_DEVICE_TABLE(vio, hvc_driver_table);
 797
 798 static struct vio_driver hvc_vio_driver = {
 799         .name           = hvc_driver_name,
 800         .id_table       = hvc_driver_table,
 801         .probe          = hvc_probe,
 802         .remove         = hvc_remove,
 803 };
 804
 805 /* Driver initialization.  Follow console initialization.  This is where the TTY
 806  * interfaces start to become available. */
 807 int __init hvc_init(void)
 808 {
 809         int rc;
 810
 811         /* We need more than hvc_count adapters due to hotplug additions. */
 812         hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
 813         if (!hvc_driver)
 814                 return -ENOMEM;
 815
 816         hvc_driver->owner = THIS_MODULE;
 817         hvc_driver->devfs_name = "hvc/";
 818         hvc_driver->driver_name = "hvc";
 819         hvc_driver->name = "hvc";
 820         hvc_driver->major = HVC_MAJOR;
 821         hvc_driver->minor_start = HVC_MINOR;
 822         hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
 823         hvc_driver->init_termios = tty_std_termios;
 824         hvc_driver->flags = TTY_DRIVER_REAL_RAW;
 825         tty_set_operations(hvc_driver, &hvc_ops);
 826
 827         if (tty_register_driver(hvc_driver))
 828                 panic("Couldn't register hvc console driver\n");
 829
 830         /* Always start the kthread because there can be hotplug vty adapters
 831          * added later. */
 832         hvc_task = kthread_run(khvcd, NULL, "khvcd");
 833         if (IS_ERR(hvc_task)) {
 834                 panic("Couldn't create kthread for console.\n");
 835                 put_tty_driver(hvc_driver);
 836                 return -EIO;
 837         }
 838
 839         /* Register as a vio device to receive callbacks */
 840         rc = vio_register_driver(&hvc_vio_driver);
 841
 842         return rc;
 843 }
 844 module_init(hvc_init);
 845
 846 /* This isn't particularily necessary due to this being a console driver
 847  * but it is nice to be thorough.
 848  */
 849 static void __exit hvc_exit(void)
 850 {
 851         kthread_stop(hvc_task);
 852
 853         vio_unregister_driver(&hvc_vio_driver);
 854         tty_unregister_driver(hvc_driver);
 855         /* return tty_struct instances allocated in hvc_init(). */
 856         put_tty_driver(hvc_driver);
 857         unregister_console(&hvc_con_driver);
 858 }
 859 module_exit(hvc_exit);