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