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 /* Used for accounting purposes */
 150 static int num_vterms = 0;
 151
 152 /*
 153  * Console APIs, NOT TTY.  These APIs are available immediately when
 154  * hvc_console_setup() finds adapters.
 155  */
 156
 157 void hvc_console_print(struct console *co, const char *b, unsigned count)
 158 {
 159         char c[16] __ALIGNED__;
 160         unsigned i = 0, n = 0;
 161         int r, donecr = 0;
 162
 163         /* Console access attempt outside of acceptable console range. */
 164         if (co->index >= MAX_NR_HVC_CONSOLES)
 165                 return;
 166
 167         /* This console adapter was removed so it is not useable. */
 168         if (vtermnos[co->index] < 0)
 169                 return;
 170
 171         while (count > 0 || i > 0) {
 172                 if (count > 0 && i < sizeof(c)) {
 173                         if (b[n] == '\n' && !donecr) {
 174                                 c[i++] = '\r';
 175                                 donecr = 1;
 176                         } else {
 177                                 c[i++] = b[n++];
 178                                 donecr = 0;
 179                                 --count;
 180                         }
 181                 } else {
 182                         r = hvc_put_chars(vtermnos[co->index], c, i);
 183                         if (r < 0) {
 184                                 /* throw away chars on error */
 185                                 i = 0;
 186                         } else if (r > 0) {
 187                                 i -= r;
 188                                 if (i > 0)
 189                                         memmove(c, c+r, i);
 190                         }
 191                 }
 192         }
 193 }
 194
 195 static struct tty_driver *hvc_console_device(struct console *c, int *index)
 196 {
 197         *index = c->index;
 198         return hvc_driver;
 199 }
 200
 201 static int __init hvc_console_setup(struct console *co, char *options)
 202 {
 203         return 0;
 204 }
 205
 206 struct console hvc_con_driver = {
 207         .name           = "hvc",
 208         .write          = hvc_console_print,
 209         .device         = hvc_console_device,
 210         .setup          = hvc_console_setup,
 211         .flags          = CON_PRINTBUFFER,
 212         .index          = -1,
 213 };
 214
 215 /* Early console initialization.  Preceeds driver initialization. */
 216 static int __init hvc_console_init(void)
 217 {
 218         int i;
 219
 220         for (i=0; i<MAX_NR_HVC_CONSOLES; i++)
 221                 vtermnos[i] = -1;
 222         num_vterms = hvc_find_vtys();
 223         register_console(&hvc_con_driver);
 224         return 0;
 225 }
 226 console_initcall(hvc_console_init);
 227
 228 /*
 229  * hvc_instantiate() is an early console discovery method which locates
 230  * consoles * prior to the vio subsystem discovering them.  Hotplugged
 231  * vty adapters do NOT get an hvc_instantiate() callback since they
 232  * appear after early console init.
 233  */
 234 int hvc_instantiate(uint32_t vtermno, int index)
 235 {
 236         if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
 237                 return -1;
 238
 239         if (vtermnos[index] != -1)
 240                 return -1;
 241
 242         vtermnos[index] = vtermno;
 243
 244         /* reserve all indices upto and including this index */
 245         if (last_hvc < index)
 246                 last_hvc = index;
 247
 248         return 0;
 249 }
 250
 251 /* Wake the sleeping khvcd */
 252 static void hvc_kick(void)
 253 {
 254         hvc_kicked = 1;
 255         wake_up_process(hvc_task);
 256 }
 257
 258 static int hvc_poll(struct hvc_struct *hp);
 259
 260 /*
 261  * NOTE: This API isn't used if the console adapter doesn't support interrupts.
 262  * In this case the console is poll driven.
 263  */
 264 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
 265 {
 266         /* if hvc_poll request a repoll, then kick the hvcd thread */
 267         if (hvc_poll(dev_instance))
 268                 hvc_kick();
 269         return IRQ_HANDLED;
 270 }
 271
 272 static void hvc_unthrottle(struct tty_struct *tty)
 273 {
 274         hvc_kick();
 275 }
 276
 277 /*
 278  * The TTY interface won't be used until after the vio layer has exposed the vty
 279  * adapter to the kernel.
 280  */
 281 static int hvc_open(struct tty_struct *tty, struct file * filp)
 282 {
 283         struct hvc_struct *hp;
 284         unsigned long flags;
 285         int irq = NO_IRQ;
 286         int rc = 0;
 287         struct kobject *kobjp;
 288
 289         /* Auto increments kobject reference if found. */
 290         if (!(hp = hvc_get_by_index(tty->index))) {
 291                 printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
 292                 return -ENODEV;
 293         }
 294
 295         spin_lock_irqsave(&hp->lock, flags);
 296         /* Check and then increment for fast path open. */
 297         if (hp->count++ > 0) {
 298                 spin_unlock_irqrestore(&hp->lock, flags);
 299                 hvc_kick();
 300                 return 0;
 301         } /* else count == 0 */
 302
 303         tty->driver_data = hp;
 304         hp->tty = tty;
 305         /* Save for request_irq outside of spin_lock. */
 306         irq = hp->irq;
 307         if (irq != NO_IRQ)
 308                 hp->irq_requested = 1;
 309
 310         kobjp = &hp->kobj;
 311
 312         spin_unlock_irqrestore(&hp->lock, flags);
 313         /* check error, fallback to non-irq */
 314         if (irq != NO_IRQ)
 315                 rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp);
 316
 317         /*
 318          * If the request_irq() fails and we return an error.  The tty layer
 319          * will call hvc_close() after a failed open but we don't want to clean
 320          * up there so we'll clean up here and clear out the previously set
 321          * tty fields and return the kobject reference.
 322          */
 323         if (rc) {
 324                 spin_lock_irqsave(&hp->lock, flags);
 325                 hp->tty = NULL;
 326                 hp->irq_requested = 0;
 327                 spin_unlock_irqrestore(&hp->lock, flags);
 328                 tty->driver_data = NULL;
 329                 kobject_put(kobjp);
 330                 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
 331         }
 332         /* Force wakeup of the polling thread */
 333         hvc_kick();
 334
 335         return rc;
 336 }
 337
 338 static void hvc_close(struct tty_struct *tty, struct file * filp)
 339 {
 340         struct hvc_struct *hp;
 341         struct kobject *kobjp;
 342         int irq = NO_IRQ;
 343         unsigned long flags;
 344
 345         if (tty_hung_up_p(filp))
 346                 return;
 347
 348         /*
 349          * No driver_data means that this close was issued after a failed
 350          * hvc_open by the tty layer's release_dev() function and we can just
 351          * exit cleanly because the kobject reference wasn't made.
 352          */
 353         if (!tty->driver_data)
 354                 return;
 355
 356         hp = tty->driver_data;
 357         spin_lock_irqsave(&hp->lock, flags);
 358
 359         kobjp = &hp->kobj;
 360         if (--hp->count == 0) {
 361                 if (hp->irq_requested)
 362                         irq = hp->irq;
 363                 hp->irq_requested = 0;
 364
 365                 /* We are done with the tty pointer now. */
 366                 hp->tty = NULL;
 367                 spin_unlock_irqrestore(&hp->lock, flags);
 368
 369                 /*
 370                  * Chain calls chars_in_buffer() and returns immediately if
 371                  * there is no buffered data otherwise sleeps on a wait queue
 372                  * waking periodically to check chars_in_buffer().
 373                  */
 374                 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
 375
 376                 if (irq != NO_IRQ)
 377                         free_irq(irq, hp);
 378
 379         } else {
 380                 if (hp->count < 0)
 381                         printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
 382                                 hp->vtermno, hp->count);
 383                 spin_unlock_irqrestore(&hp->lock, flags);
 384         }
 385
 386         kobject_put(kobjp);
 387 }
 388
 389 static void hvc_hangup(struct tty_struct *tty)
 390 {
 391         struct hvc_struct *hp = tty->driver_data;
 392         unsigned long flags;
 393         int irq = NO_IRQ;
 394         int temp_open_count;
 395         struct kobject *kobjp;
 396
 397         if (!hp)
 398                 return;
 399
 400         spin_lock_irqsave(&hp->lock, flags);
 401
 402         /*
 403          * The N_TTY line discipline has problems such that in a close vs
 404          * open->hangup case this can be called after the final close so prevent
 405          * that from happening for now.
 406          */
 407         if (hp->count <= 0) {
 408                 spin_unlock_irqrestore(&hp->lock, flags);
 409                 return;
 410         }
 411
 412         kobjp = &hp->kobj;
 413         temp_open_count = hp->count;
 414         hp->count = 0;
 415         hp->n_outbuf = 0;
 416         hp->tty = NULL;
 417         if (hp->irq_requested)
 418                 /* Saved for use outside of spin_lock. */
 419                 irq = hp->irq;
 420         hp->irq_requested = 0;
 421         spin_unlock_irqrestore(&hp->lock, flags);
 422         if (irq != NO_IRQ)
 423                 free_irq(irq, hp);
 424         while(temp_open_count) {
 425                 --temp_open_count;
 426                 kobject_put(kobjp);
 427         }
 428 }
 429
 430 /*
 431  * Push buffered characters whether they were just recently buffered or waiting
 432  * on a blocked hypervisor.  Call this function with hp->lock held.
 433  */
 434 static void hvc_push(struct hvc_struct *hp)
 435 {
 436         int n;
 437
 438         n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
 439         if (n <= 0) {
 440                 if (n == 0)
 441                         return;
 442                 /* throw away output on error; this happens when
 443                    there is no session connected to the vterm. */
 444                 hp->n_outbuf = 0;
 445         } else
 446                 hp->n_outbuf -= n;
 447         if (hp->n_outbuf > 0)
 448                 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
 449         else
 450                 hp->do_wakeup = 1;
 451 }
 452
 453 static inline int __hvc_write_kernel(struct hvc_struct *hp,
 454                                    const unsigned char *buf, int count)
 455 {
 456         unsigned long flags;
 457         int rsize, written = 0;
 458
 459         spin_lock_irqsave(&hp->lock, flags);
 460
 461         /* Push pending writes */
 462         if (hp->n_outbuf > 0)
 463                 hvc_push(hp);
 464
 465         while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
 466                 if (rsize > count)
 467                         rsize = count;
 468                 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
 469                 count -= rsize;
 470                 buf += rsize;
 471                 hp->n_outbuf += rsize;
 472                 written += rsize;
 473                 hvc_push(hp);
 474         }
 475         spin_unlock_irqrestore(&hp->lock, flags);
 476
 477         return written;
 478 }
 479 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
 480 {
 481         struct hvc_struct *hp = tty->driver_data;
 482         int written;
 483
 484         /* This write was probably executed during a tty close. */
 485         if (!hp)
 486                 return -EPIPE;
 487
 488         if (hp->count <= 0)
 489                 return -EIO;
 490
 491         written = __hvc_write_kernel(hp, buf, count);
 492
 493         /*
 494          * Racy, but harmless, kick thread if there is still pending data.
 495          * There really is nothing wrong with kicking the thread, even if there
 496          * is no buffered data.
 497          */
 498         if (hp->n_outbuf)
 499                 hvc_kick();
 500
 501         return written;
 502 }
 503
 504 /*
 505  * This is actually a contract between the driver and the tty layer outlining
 506  * how much write room the driver can guarentee will be sent OR BUFFERED.  This
 507  * driver MUST honor the return value.
 508  */
 509 static int hvc_write_room(struct tty_struct *tty)
 510 {
 511         struct hvc_struct *hp = tty->driver_data;
 512
 513         if (!hp)
 514                 return -1;
 515
 516         return N_OUTBUF - hp->n_outbuf;
 517 }
 518
 519 static int hvc_chars_in_buffer(struct tty_struct *tty)
 520 {
 521         struct hvc_struct *hp = tty->driver_data;
 522
 523         if (!hp)
 524                 return -1;
 525         return hp->n_outbuf;
 526 }
 527
 528 #define HVC_POLL_READ   0x00000001
 529 #define HVC_POLL_WRITE  0x00000002
 530 #define HVC_POLL_QUICK  0x00000004
 531
 532 static int hvc_poll(struct hvc_struct *hp)
 533 {
 534         struct tty_struct *tty;
 535         int i, n, poll_mask = 0;
 536         char buf[N_INBUF] __ALIGNED__;
 537         unsigned long flags;
 538         int read_total = 0;
 539
 540         spin_lock_irqsave(&hp->lock, flags);
 541
 542         /* Push pending writes */
 543         if (hp->n_outbuf > 0)
 544                 hvc_push(hp);
 545         /* Reschedule us if still some write pending */
 546         if (hp->n_outbuf > 0)
 547                 poll_mask |= HVC_POLL_WRITE;
 548
 549         /* No tty attached, just skip */
 550         tty = hp->tty;
 551         if (tty == NULL)
 552                 goto bail;
 553
 554         /* Now check if we can get data (are we throttled ?) */
 555         if (test_bit(TTY_THROTTLED, &tty->flags))
 556                 goto throttled;
 557
 558         /* If we aren't interrupt driven and aren't throttled, we always
 559          * request a reschedule
 560          */
 561         if (hp->irq == NO_IRQ)
 562                 poll_mask |= HVC_POLL_READ;
 563
 564         /* Read data if any */
 565         for (;;) {
 566                 int count = N_INBUF;
 567                 if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
 568                         count = TTY_FLIPBUF_SIZE - tty->flip.count;
 569
 570                 /* If flip is full, just reschedule a later read */
 571                 if (count == 0) {
 572                         poll_mask |= HVC_POLL_READ;
 573                         break;
 574                 }
 575
 576                 n = hvc_get_chars(hp->vtermno, buf, count);
 577                 if (n <= 0) {
 578                         /* Hangup the tty when disconnected from host */
 579                         if (n == -EPIPE) {
 580                                 spin_unlock_irqrestore(&hp->lock, flags);
 581                                 tty_hangup(tty);
 582                                 spin_lock_irqsave(&hp->lock, flags);
 583                         }
 584                         break;
 585                 }
 586                 for (i = 0; i < n; ++i) {
 587 #ifdef CONFIG_MAGIC_SYSRQ
 588                         if (hp->index == hvc_con_driver.index) {
 589                                 /* Handle the SysRq Hack */
 590                                 /* XXX should support a sequence */
 591                                 if (buf[i] == '\x0f') { /* ^O */
 592                                         sysrq_pressed = 1;
 593                                         continue;
 594                                 } else if (sysrq_pressed) {
 595                                         handle_sysrq(buf[i], NULL, tty);
 596                                         sysrq_pressed = 0;
 597                                         continue;
 598                                 }
 599                         }
 600 #endif /* CONFIG_MAGIC_SYSRQ */
 601                         tty_insert_flip_char(tty, buf[i], 0);
 602                 }
 603
 604                 if (tty->flip.count)
 605                         tty_schedule_flip(tty);
 606
 607                 /*
 608                  * Account for the total amount read in one loop, and if above
 609                  * 64 bytes, we do a quick schedule loop to let the tty grok
 610                  * the data and eventually throttle us.
 611                  */
 612                 read_total += n;
 613                 if (read_total >= 64) {
 614                         poll_mask |= HVC_POLL_QUICK;
 615                         break;
 616                 }
 617         }
 618  throttled:
 619         /* Wakeup write queue if necessary */
 620         if (hp->do_wakeup) {
 621                 hp->do_wakeup = 0;
 622                 tty_wakeup(tty);
 623         }
 624  bail:
 625         spin_unlock_irqrestore(&hp->lock, flags);
 626
 627         return poll_mask;
 628 }
 629
 630 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
 631 extern cpumask_t cpus_in_xmon;
 632 #else
 633 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
 634 #endif
 635
 636 /*
 637  * This kthread is either polling or interrupt driven.  This is determined by
 638  * calling hvc_poll() who determines whether a console adapter support
 639  * interrupts.
 640  */
 641 int khvcd(void *unused)
 642 {
 643         int poll_mask;
 644         struct hvc_struct *hp;
 645
 646         __set_current_state(TASK_RUNNING);
 647         do {
 648                 poll_mask = 0;
 649                 hvc_kicked = 0;
 650                 wmb();
 651                 if (cpus_empty(cpus_in_xmon)) {
 652                         spin_lock(&hvc_structs_lock);
 653                         list_for_each_entry(hp, &hvc_structs, next) {
 654                                 /*hp = list_entry(node, struct hvc_struct, * next); */
 655                                 poll_mask |= hvc_poll(hp);
 656                         }
 657                         spin_unlock(&hvc_structs_lock);
 658                 } else
 659                         poll_mask |= HVC_POLL_READ;
 660                 if (hvc_kicked)
 661                         continue;
 662                 if (poll_mask & HVC_POLL_QUICK) {
 663                         yield();
 664                         continue;
 665                 }
 666                 set_current_state(TASK_INTERRUPTIBLE);
 667                 if (!hvc_kicked) {
 668                         if (poll_mask == 0)
 669                                 schedule();
 670                         else
 671                                 msleep_interruptible(TIMEOUT);
 672                 }
 673                 __set_current_state(TASK_RUNNING);
 674         } while (!kthread_should_stop());
 675
 676         return 0;
 677 }
 678
 679 static struct tty_operations hvc_ops = {
 680         .open = hvc_open,
 681         .close = hvc_close,
 682         .write = hvc_write,
 683         .hangup = hvc_hangup,
 684         .unthrottle = hvc_unthrottle,
 685         .write_room = hvc_write_room,
 686         .chars_in_buffer = hvc_chars_in_buffer,
 687 };
 688
 689 /* callback when the kboject ref count reaches zero. */
 690 static void destroy_hvc_struct(struct kobject *kobj)
 691 {
 692         struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
 693         unsigned long flags;
 694
 695         spin_lock(&hvc_structs_lock);
 696
 697         spin_lock_irqsave(&hp->lock, flags);
 698         list_del(&(hp->next));
 699         spin_unlock_irqrestore(&hp->lock, flags);
 700
 701         spin_unlock(&hvc_structs_lock);
 702
 703         kfree(hp);
 704 }
 705
 706 static struct kobj_type hvc_kobj_type = {
 707         .release = destroy_hvc_struct,
 708 };
 709
 710 static int __devinit hvc_probe(
 711                 struct vio_dev *dev,
 712                 const struct vio_device_id *id)
 713 {
 714         struct hvc_struct *hp;
 715         int i;
 716
 717         /* probed with invalid parameters. */
 718         if (!dev || !id)
 719                 return -EPERM;
 720
 721         hp = kmalloc(sizeof(*hp), GFP_KERNEL);
 722         if (!hp)
 723                 return -ENOMEM;
 724
 725         memset(hp, 0x00, sizeof(*hp));
 726         hp->vtermno = dev->unit_address;
 727         hp->vdev = dev;
 728         hp->vdev->dev.driver_data = hp;
 729         hp->irq = dev->irq;
 730
 731         kobject_init(&hp->kobj);
 732         hp->kobj.ktype = &hvc_kobj_type;
 733
 734         spin_lock_init(&hp->lock);
 735         spin_lock(&hvc_structs_lock);
 736
 737         /*
 738          * find index to use:
 739          * see if this vterm id matches one registered for console.
 740          */
 741         for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
 742                 if (vtermnos[i] == hp->vtermno)
 743                         break;
 744
 745         /* no matching slot, just use a counter */
 746         if (i >= MAX_NR_HVC_CONSOLES)
 747                 i = ++last_hvc;
 748
 749         hp->index = i;
 750
 751         list_add_tail(&(hp->next), &hvc_structs);
 752         spin_unlock(&hvc_structs_lock);
 753
 754         return 0;
 755 }
 756
 757 static int __devexit hvc_remove(struct vio_dev *dev)
 758 {
 759         struct hvc_struct *hp = dev->dev.driver_data;
 760         unsigned long flags;
 761         struct kobject *kobjp;
 762         struct tty_struct *tty;
 763
 764         spin_lock_irqsave(&hp->lock, flags);
 765         tty = hp->tty;
 766         kobjp = &hp->kobj;
 767
 768         if (hp->index < MAX_NR_HVC_CONSOLES)
 769                 vtermnos[hp->index] = -1;
 770
 771         /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
 772
 773         spin_unlock_irqrestore(&hp->lock, flags);
 774
 775         /*
 776          * We 'put' the instance that was grabbed when the kobject instance
 777          * was intialized using kobject_init().  Let the last holder of this
 778          * kobject cause it to be removed, which will probably be the tty_hangup
 779          * below.
 780          */
 781         kobject_put(kobjp);
 782
 783         /*
 784          * This function call will auto chain call hvc_hangup.  The tty should
 785          * always be valid at this time unless a simultaneous tty close already
 786          * cleaned up the hvc_struct.
 787          */
 788         if (tty)
 789                 tty_hangup(tty);
 790         return 0;
 791 }
 792
 793 char hvc_driver_name[] = "hvc_console";
 794
 795 static struct vio_device_id hvc_driver_table[] __devinitdata= {
 796         {"serial", "hvterm1"},
 797         { NULL, }
 798 };
 799 MODULE_DEVICE_TABLE(vio, hvc_driver_table);
 800
 801 static struct vio_driver hvc_vio_driver = {
 802         .name           = hvc_driver_name,
 803         .id_table       = hvc_driver_table,
 804         .probe          = hvc_probe,
 805         .remove         = hvc_remove,
 806 };
 807
 808 /* Driver initialization.  Follow console initialization.  This is where the TTY
 809  * interfaces start to become available. */
 810 int __init hvc_init(void)
 811 {
 812         int rc;
 813
 814         /* We need more than num_vterms adapters due to hotplug additions. */
 815         hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
 816         /* hvc_driver = alloc_tty_driver(num_vterms); */
 817         if (!hvc_driver)
 818                 return -ENOMEM;
 819
 820         hvc_driver->owner = THIS_MODULE;
 821         hvc_driver->devfs_name = "hvc/";
 822         hvc_driver->driver_name = "hvc";
 823         hvc_driver->name = "hvc";
 824         hvc_driver->major = HVC_MAJOR;
 825         hvc_driver->minor_start = HVC_MINOR;
 826         hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
 827         hvc_driver->init_termios = tty_std_termios;
 828         hvc_driver->flags = TTY_DRIVER_REAL_RAW;
 829         tty_set_operations(hvc_driver, &hvc_ops);
 830
 831         if (tty_register_driver(hvc_driver))
 832                 panic("Couldn't register hvc console driver\n");
 833
 834         /* Always start the kthread because there can be hotplug vty adapters
 835          * added later. */
 836         hvc_task = kthread_run(khvcd, NULL, "khvcd");
 837         if (IS_ERR(hvc_task)) {
 838                 panic("Couldn't create kthread for console.\n");
 839                 put_tty_driver(hvc_driver);
 840                 return -EIO;
 841         }
 842
 843         /* Register as a vio device to receive callbacks */
 844         rc = vio_register_driver(&hvc_vio_driver);
 845
 846         return rc;
 847 }
 848 module_init(hvc_init);
 849
 850 /* This isn't particularily necessary due to this being a console driver
 851  * but it is nice to be thorough.
 852  */
 853 static void __exit hvc_exit(void)
 854 {
 855         kthread_stop(hvc_task);
 856
 857         vio_unregister_driver(&hvc_vio_driver);
 858         tty_unregister_driver(hvc_driver);
 859         /* return tty_struct instances allocated in hvc_init(). */
 860         put_tty_driver(hvc_driver);
 861         unregister_console(&hvc_con_driver);
 862 }
 863 module_exit(hvc_exit);