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