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         if (vtermnos[c->index] == -1)
 196                 return NULL;
 197
 198         *index = c->index;
 199         return hvc_driver;
 200 }
 201
 202 static int __init hvc_console_setup(struct console *co, char *options)
 203 {
 204         if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
 205                 return -ENODEV;
 206
 207         if (vtermnos[co->index] == -1)
 208                 return -ENODEV;
 209
 210         return 0;
 211 }
 212
 213 struct console hvc_con_driver = {
 214         .name           = "hvc",
 215         .write          = hvc_console_print,
 216         .device         = hvc_console_device,
 217         .setup          = hvc_console_setup,
 218         .flags          = CON_PRINTBUFFER,
 219         .index          = -1,
 220 };
 221
 222 /* Early console initialization.  Preceeds driver initialization. */
 223 static int __init hvc_console_init(void)
 224 {
 225         hvc_find_vtys();
 226         register_console(&hvc_con_driver);
 227         return 0;
 228 }
 229 console_initcall(hvc_console_init);
 230
 231 /*
 232  * hvc_instantiate() is an early console discovery method which locates
 233  * consoles * prior to the vio subsystem discovering them.  Hotplugged
 234  * vty adapters do NOT get an hvc_instantiate() callback since they
 235  * appear after early console init.
 236  */
 237 int hvc_instantiate(uint32_t vtermno, int index)
 238 {
 239         struct hvc_struct *hp;
 240
 241         if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
 242                 return -1;
 243
 244         if (vtermnos[index] != -1)
 245                 return -1;
 246
 247         /* make sure no no tty has been registerd in this index */
 248         hp = hvc_get_by_index(index);
 249         if (hp) {
 250                 kobject_put(&hp->kobj);
 251                 return -1;
 252         }
 253
 254         vtermnos[index] = vtermno;
 255
 256         /* reserve all indices upto and including this index */
 257         if (last_hvc < index)
 258                 last_hvc = index;
 259
 260         return 0;
 261 }
 262
 263 /* Wake the sleeping khvcd */
 264 static void hvc_kick(void)
 265 {
 266         hvc_kicked = 1;
 267         wake_up_process(hvc_task);
 268 }
 269
 270 static int hvc_poll(struct hvc_struct *hp);
 271
 272 /*
 273  * NOTE: This API isn't used if the console adapter doesn't support interrupts.
 274  * In this case the console is poll driven.
 275  */
 276 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
 277 {
 278         /* if hvc_poll request a repoll, then kick the hvcd thread */
 279         if (hvc_poll(dev_instance))
 280                 hvc_kick();
 281         return IRQ_HANDLED;
 282 }
 283
 284 static void hvc_unthrottle(struct tty_struct *tty)
 285 {
 286         hvc_kick();
 287 }
 288
 289 /*
 290  * The TTY interface won't be used until after the vio layer has exposed the vty
 291  * adapter to the kernel.
 292  */
 293 static int hvc_open(struct tty_struct *tty, struct file * filp)
 294 {
 295         struct hvc_struct *hp;
 296         unsigned long flags;
 297         int irq = NO_IRQ;
 298         int rc = 0;
 299         struct kobject *kobjp;
 300
 301         /* Auto increments kobject reference if found. */
 302         if (!(hp = hvc_get_by_index(tty->index))) {
 303                 printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
 304                 return -ENODEV;
 305         }
 306
 307         spin_lock_irqsave(&hp->lock, flags);
 308         /* Check and then increment for fast path open. */
 309         if (hp->count++ > 0) {
 310                 spin_unlock_irqrestore(&hp->lock, flags);
 311                 hvc_kick();
 312                 return 0;
 313         } /* else count == 0 */
 314
 315         tty->driver_data = hp;
 316         hp->tty = tty;
 317         /* Save for request_irq outside of spin_lock. */
 318         irq = hp->irq;
 319         if (irq != NO_IRQ)
 320                 hp->irq_requested = 1;
 321
 322         kobjp = &hp->kobj;
 323
 324         spin_unlock_irqrestore(&hp->lock, flags);
 325         /* check error, fallback to non-irq */
 326         if (irq != NO_IRQ)
 327                 rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp);
 328
 329         /*
 330          * If the request_irq() fails and we return an error.  The tty layer
 331          * will call hvc_close() after a failed open but we don't want to clean
 332          * up there so we'll clean up here and clear out the previously set
 333          * tty fields and return the kobject reference.
 334          */
 335         if (rc) {
 336                 spin_lock_irqsave(&hp->lock, flags);
 337                 hp->tty = NULL;
 338                 hp->irq_requested = 0;
 339                 spin_unlock_irqrestore(&hp->lock, flags);
 340                 tty->driver_data = NULL;
 341                 kobject_put(kobjp);
 342                 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
 343         }
 344         /* Force wakeup of the polling thread */
 345         hvc_kick();
 346
 347         return rc;
 348 }
 349
 350 static void hvc_close(struct tty_struct *tty, struct file * filp)
 351 {
 352         struct hvc_struct *hp;
 353         struct kobject *kobjp;
 354         int irq = NO_IRQ;
 355         unsigned long flags;
 356
 357         if (tty_hung_up_p(filp))
 358                 return;
 359
 360         /*
 361          * No driver_data means that this close was issued after a failed
 362          * hvc_open by the tty layer's release_dev() function and we can just
 363          * exit cleanly because the kobject reference wasn't made.
 364          */
 365         if (!tty->driver_data)
 366                 return;
 367
 368         hp = tty->driver_data;
 369         spin_lock_irqsave(&hp->lock, flags);
 370
 371         kobjp = &hp->kobj;
 372         if (--hp->count == 0) {
 373                 if (hp->irq_requested)
 374                         irq = hp->irq;
 375                 hp->irq_requested = 0;
 376
 377                 /* We are done with the tty pointer now. */
 378                 hp->tty = NULL;
 379                 spin_unlock_irqrestore(&hp->lock, flags);
 380
 381                 /*
 382                  * Chain calls chars_in_buffer() and returns immediately if
 383                  * there is no buffered data otherwise sleeps on a wait queue
 384                  * waking periodically to check chars_in_buffer().
 385                  */
 386                 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
 387
 388                 if (irq != NO_IRQ)
 389                         free_irq(irq, hp);
 390
 391         } else {
 392                 if (hp->count < 0)
 393                         printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
 394                                 hp->vtermno, hp->count);
 395                 spin_unlock_irqrestore(&hp->lock, flags);
 396         }
 397
 398         kobject_put(kobjp);
 399 }
 400
 401 static void hvc_hangup(struct tty_struct *tty)
 402 {
 403         struct hvc_struct *hp = tty->driver_data;
 404         unsigned long flags;
 405         int irq = NO_IRQ;
 406         int temp_open_count;
 407         struct kobject *kobjp;
 408
 409         if (!hp)
 410                 return;
 411
 412         spin_lock_irqsave(&hp->lock, flags);
 413
 414         /*
 415          * The N_TTY line discipline has problems such that in a close vs
 416          * open->hangup case this can be called after the final close so prevent
 417          * that from happening for now.
 418          */
 419         if (hp->count <= 0) {
 420                 spin_unlock_irqrestore(&hp->lock, flags);
 421                 return;
 422         }
 423
 424         kobjp = &hp->kobj;
 425         temp_open_count = hp->count;
 426         hp->count = 0;
 427         hp->n_outbuf = 0;
 428         hp->tty = NULL;
 429         if (hp->irq_requested)
 430                 /* Saved for use outside of spin_lock. */
 431                 irq = hp->irq;
 432         hp->irq_requested = 0;
 433         spin_unlock_irqrestore(&hp->lock, flags);
 434         if (irq != NO_IRQ)
 435                 free_irq(irq, hp);
 436         while(temp_open_count) {
 437                 --temp_open_count;
 438                 kobject_put(kobjp);
 439         }
 440 }
 441
 442 /*
 443  * Push buffered characters whether they were just recently buffered or waiting
 444  * on a blocked hypervisor.  Call this function with hp->lock held.
 445  */
 446 static void hvc_push(struct hvc_struct *hp)
 447 {
 448         int n;
 449
 450         n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
 451         if (n <= 0) {
 452                 if (n == 0)
 453                         return;
 454                 /* throw away output on error; this happens when
 455                    there is no session connected to the vterm. */
 456                 hp->n_outbuf = 0;
 457         } else
 458                 hp->n_outbuf -= n;
 459         if (hp->n_outbuf > 0)
 460                 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
 461         else
 462                 hp->do_wakeup = 1;
 463 }
 464
 465 static inline int __hvc_write_kernel(struct hvc_struct *hp,
 466                                    const unsigned char *buf, int count)
 467 {
 468         unsigned long flags;
 469         int rsize, written = 0;
 470
 471         spin_lock_irqsave(&hp->lock, flags);
 472
 473         /* Push pending writes */
 474         if (hp->n_outbuf > 0)
 475                 hvc_push(hp);
 476
 477         while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
 478                 if (rsize > count)
 479                         rsize = count;
 480                 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
 481                 count -= rsize;
 482                 buf += rsize;
 483                 hp->n_outbuf += rsize;
 484                 written += rsize;
 485                 hvc_push(hp);
 486         }
 487         spin_unlock_irqrestore(&hp->lock, flags);
 488
 489         return written;
 490 }
 491 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
 492 {
 493         struct hvc_struct *hp = tty->driver_data;
 494         int written;
 495
 496         /* This write was probably executed during a tty close. */
 497         if (!hp)
 498                 return -EPIPE;
 499
 500         if (hp->count <= 0)
 501                 return -EIO;
 502
 503         written = __hvc_write_kernel(hp, buf, count);
 504
 505         /*
 506          * Racy, but harmless, kick thread if there is still pending data.
 507          * There really is nothing wrong with kicking the thread, even if there
 508          * is no buffered data.
 509          */
 510         if (hp->n_outbuf)
 511                 hvc_kick();
 512
 513         return written;
 514 }
 515
 516 /*
 517  * This is actually a contract between the driver and the tty layer outlining
 518  * how much write room the driver can guarentee will be sent OR BUFFERED.  This
 519  * driver MUST honor the return value.
 520  */
 521 static int hvc_write_room(struct tty_struct *tty)
 522 {
 523         struct hvc_struct *hp = tty->driver_data;
 524
 525         if (!hp)
 526                 return -1;
 527
 528         return N_OUTBUF - hp->n_outbuf;
 529 }
 530
 531 static int hvc_chars_in_buffer(struct tty_struct *tty)
 532 {
 533         struct hvc_struct *hp = tty->driver_data;
 534
 535         if (!hp)
 536                 return -1;
 537         return hp->n_outbuf;
 538 }
 539
 540 #define HVC_POLL_READ   0x00000001
 541 #define HVC_POLL_WRITE  0x00000002
 542 #define HVC_POLL_QUICK  0x00000004
 543
 544 static int hvc_poll(struct hvc_struct *hp)
 545 {
 546         struct tty_struct *tty;
 547         int i, n, poll_mask = 0;
 548         char buf[N_INBUF] __ALIGNED__;
 549         unsigned long flags;
 550         int read_total = 0;
 551
 552         spin_lock_irqsave(&hp->lock, flags);
 553
 554         /* Push pending writes */
 555         if (hp->n_outbuf > 0)
 556                 hvc_push(hp);
 557         /* Reschedule us if still some write pending */
 558         if (hp->n_outbuf > 0)
 559                 poll_mask |= HVC_POLL_WRITE;
 560
 561         /* No tty attached, just skip */
 562         tty = hp->tty;
 563         if (tty == NULL)
 564                 goto bail;
 565
 566         /* Now check if we can get data (are we throttled ?) */
 567         if (test_bit(TTY_THROTTLED, &tty->flags))
 568                 goto throttled;
 569
 570         /* If we aren't interrupt driven and aren't throttled, we always
 571          * request a reschedule
 572          */
 573         if (hp->irq == NO_IRQ)
 574                 poll_mask |= HVC_POLL_READ;
 575
 576         /* Read data if any */
 577         for (;;) {
 578                 int count = N_INBUF;
 579                 if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
 580                         count = TTY_FLIPBUF_SIZE - tty->flip.count;
 581
 582                 /* If flip is full, just reschedule a later read */
 583                 if (count == 0) {
 584                         poll_mask |= HVC_POLL_READ;
 585                         break;
 586                 }
 587
 588                 n = hvc_get_chars(hp->vtermno, buf, count);
 589                 if (n <= 0) {
 590                         /* Hangup the tty when disconnected from host */
 591                         if (n == -EPIPE) {
 592                                 spin_unlock_irqrestore(&hp->lock, flags);
 593                                 tty_hangup(tty);
 594                                 spin_lock_irqsave(&hp->lock, flags);
 595                         }
 596                         break;
 597                 }
 598                 for (i = 0; i < n; ++i) {
 599 #ifdef CONFIG_MAGIC_SYSRQ
 600                         if (hp->index == hvc_con_driver.index) {
 601                                 /* Handle the SysRq Hack */
 602                                 /* XXX should support a sequence */
 603                                 if (buf[i] == '\x0f') { /* ^O */
 604                                         sysrq_pressed = 1;
 605                                         continue;
 606                                 } else if (sysrq_pressed) {
 607                                         handle_sysrq(buf[i], NULL, tty);
 608                                         sysrq_pressed = 0;
 609                                         continue;
 610                                 }
 611                         }
 612 #endif /* CONFIG_MAGIC_SYSRQ */
 613                         tty_insert_flip_char(tty, buf[i], 0);
 614                 }
 615
 616                 if (tty->flip.count)
 617                         tty_schedule_flip(tty);
 618
 619                 /*
 620                  * Account for the total amount read in one loop, and if above
 621                  * 64 bytes, we do a quick schedule loop to let the tty grok
 622                  * the data and eventually throttle us.
 623                  */
 624                 read_total += n;
 625                 if (read_total >= 64) {
 626                         poll_mask |= HVC_POLL_QUICK;
 627                         break;
 628                 }
 629         }
 630  throttled:
 631         /* Wakeup write queue if necessary */
 632         if (hp->do_wakeup) {
 633                 hp->do_wakeup = 0;
 634                 tty_wakeup(tty);
 635         }
 636  bail:
 637         spin_unlock_irqrestore(&hp->lock, flags);
 638
 639         return poll_mask;
 640 }
 641
 642 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
 643 extern cpumask_t cpus_in_xmon;
 644 #else
 645 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
 646 #endif
 647
 648 /*
 649  * This kthread is either polling or interrupt driven.  This is determined by
 650  * calling hvc_poll() who determines whether a console adapter support
 651  * interrupts.
 652  */
 653 int khvcd(void *unused)
 654 {
 655         int poll_mask;
 656         struct hvc_struct *hp;
 657
 658         __set_current_state(TASK_RUNNING);
 659         do {
 660                 poll_mask = 0;
 661                 hvc_kicked = 0;
 662                 wmb();
 663                 if (cpus_empty(cpus_in_xmon)) {
 664                         spin_lock(&hvc_structs_lock);
 665                         list_for_each_entry(hp, &hvc_structs, next) {
 666                                 poll_mask |= hvc_poll(hp);
 667                         }
 668                         spin_unlock(&hvc_structs_lock);
 669                 } else
 670                         poll_mask |= HVC_POLL_READ;
 671                 if (hvc_kicked)
 672                         continue;
 673                 if (poll_mask & HVC_POLL_QUICK) {
 674                         yield();
 675                         continue;
 676                 }
 677                 set_current_state(TASK_INTERRUPTIBLE);
 678                 if (!hvc_kicked) {
 679                         if (poll_mask == 0)
 680                                 schedule();
 681                         else
 682                                 msleep_interruptible(TIMEOUT);
 683                 }
 684                 __set_current_state(TASK_RUNNING);
 685         } while (!kthread_should_stop());
 686
 687         return 0;
 688 }
 689
 690 static struct tty_operations hvc_ops = {
 691         .open = hvc_open,
 692         .close = hvc_close,
 693         .write = hvc_write,
 694         .hangup = hvc_hangup,
 695         .unthrottle = hvc_unthrottle,
 696         .write_room = hvc_write_room,
 697         .chars_in_buffer = hvc_chars_in_buffer,
 698 };
 699
 700 /* callback when the kboject ref count reaches zero. */
 701 static void destroy_hvc_struct(struct kobject *kobj)
 702 {
 703         struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
 704         unsigned long flags;
 705
 706         spin_lock(&hvc_structs_lock);
 707
 708         spin_lock_irqsave(&hp->lock, flags);
 709         list_del(&(hp->next));
 710         spin_unlock_irqrestore(&hp->lock, flags);
 711
 712         spin_unlock(&hvc_structs_lock);
 713
 714         kfree(hp);
 715 }
 716
 717 static struct kobj_type hvc_kobj_type = {
 718         .release = destroy_hvc_struct,
 719 };
 720
 721 static int __devinit hvc_probe(
 722                 struct vio_dev *dev,
 723                 const struct vio_device_id *id)
 724 {
 725         struct hvc_struct *hp;
 726         int i;
 727
 728         /* probed with invalid parameters. */
 729         if (!dev || !id)
 730                 return -EPERM;
 731
 732         hp = kmalloc(sizeof(*hp), GFP_KERNEL);
 733         if (!hp)
 734                 return -ENOMEM;
 735
 736         memset(hp, 0x00, sizeof(*hp));
 737         hp->vtermno = dev->unit_address;
 738         hp->vdev = dev;
 739         hp->vdev->dev.driver_data = hp;
 740         hp->irq = dev->irq;
 741
 742         kobject_init(&hp->kobj);
 743         hp->kobj.ktype = &hvc_kobj_type;
 744
 745         spin_lock_init(&hp->lock);
 746         spin_lock(&hvc_structs_lock);
 747
 748         /*
 749          * find index to use:
 750          * see if this vterm id matches one registered for console.
 751          */
 752         for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
 753                 if (vtermnos[i] == hp->vtermno)
 754                         break;
 755
 756         /* no matching slot, just use a counter */
 757         if (i >= MAX_NR_HVC_CONSOLES)
 758                 i = ++last_hvc;
 759
 760         hp->index = i;
 761
 762         list_add_tail(&(hp->next), &hvc_structs);
 763         spin_unlock(&hvc_structs_lock);
 764
 765         return 0;
 766 }
 767
 768 static int __devexit hvc_remove(struct vio_dev *dev)
 769 {
 770         struct hvc_struct *hp = dev->dev.driver_data;
 771         unsigned long flags;
 772         struct kobject *kobjp;
 773         struct tty_struct *tty;
 774
 775         spin_lock_irqsave(&hp->lock, flags);
 776         tty = hp->tty;
 777         kobjp = &hp->kobj;
 778
 779         if (hp->index < MAX_NR_HVC_CONSOLES)
 780                 vtermnos[hp->index] = -1;
 781
 782         /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
 783
 784         spin_unlock_irqrestore(&hp->lock, flags);
 785
 786         /*
 787          * We 'put' the instance that was grabbed when the kobject instance
 788          * was intialized using kobject_init().  Let the last holder of this
 789          * kobject cause it to be removed, which will probably be the tty_hangup
 790          * below.
 791          */
 792         kobject_put(kobjp);
 793
 794         /*
 795          * This function call will auto chain call hvc_hangup.  The tty should
 796          * always be valid at this time unless a simultaneous tty close already
 797          * cleaned up the hvc_struct.
 798          */
 799         if (tty)
 800                 tty_hangup(tty);
 801         return 0;
 802 }
 803
 804 char hvc_driver_name[] = "hvc_console";
 805
 806 static struct vio_device_id hvc_driver_table[] __devinitdata= {
 807         {"serial", "hvterm1"},
 808         { NULL, }
 809 };
 810 MODULE_DEVICE_TABLE(vio, hvc_driver_table);
 811
 812 static struct vio_driver hvc_vio_driver = {
 813         .name           = hvc_driver_name,
 814         .id_table       = hvc_driver_table,
 815         .probe          = hvc_probe,
 816         .remove         = hvc_remove,
 817 };
 818
 819 /* Driver initialization.  Follow console initialization.  This is where the TTY
 820  * interfaces start to become available. */
 821 int __init hvc_init(void)
 822 {
 823         int rc;
 824
 825         /* We need more than hvc_count adapters due to hotplug additions. */
 826         hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
 827         if (!hvc_driver)
 828                 return -ENOMEM;
 829
 830         hvc_driver->owner = THIS_MODULE;
 831         hvc_driver->devfs_name = "hvc/";
 832         hvc_driver->driver_name = "hvc";
 833         hvc_driver->name = "hvc";
 834         hvc_driver->major = HVC_MAJOR;
 835         hvc_driver->minor_start = HVC_MINOR;
 836         hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
 837         hvc_driver->init_termios = tty_std_termios;
 838         hvc_driver->flags = TTY_DRIVER_REAL_RAW;
 839         tty_set_operations(hvc_driver, &hvc_ops);
 840
 841         if (tty_register_driver(hvc_driver))
 842                 panic("Couldn't register hvc console driver\n");
 843
 844         /* Always start the kthread because there can be hotplug vty adapters
 845          * added later. */
 846         hvc_task = kthread_run(khvcd, NULL, "khvcd");
 847         if (IS_ERR(hvc_task)) {
 848                 panic("Couldn't create kthread for console.\n");
 849                 put_tty_driver(hvc_driver);
 850                 return -EIO;
 851         }
 852
 853         /* Register as a vio device to receive callbacks */
 854         rc = vio_register_driver(&hvc_vio_driver);
 855
 856         return rc;
 857 }
 858 module_init(hvc_init);
 859
 860 /* This isn't particularily necessary due to this being a console driver
 861  * but it is nice to be thorough.
 862  */
 863 static void __exit hvc_exit(void)
 864 {
 865         kthread_stop(hvc_task);
 866
 867         vio_unregister_driver(&hvc_vio_driver);
 868         tty_unregister_driver(hvc_driver);
 869         /* return tty_struct instances allocated in hvc_init(). */
 870         put_tty_driver(hvc_driver);
 871         unregister_console(&hvc_con_driver);
 872 }
 873 module_exit(hvc_exit);