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 <linux/freezer.h> 42 43#include <asm/uaccess.h> 44 45#include "hvc_console.h" 46 47#define HVC_MAJOR 229 48#define HVC_MINOR 0 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 * These sizes are most efficient for vio, because they are the 58 * native transfer size. We could make them selectable in the 59 * future to better deal with backends that want other buffer sizes. 60 */ 61#define N_OUTBUF 16 62#define N_INBUF 16 63 64#define __ALIGNED__ __attribute__((__aligned__(sizeof(long)))) 65 66static struct tty_driver *hvc_driver; 67static struct task_struct *hvc_task; 68 69/* Picks up late kicks after list walk but before schedule() */ 70static int hvc_kicked; 71 72#ifdef CONFIG_MAGIC_SYSRQ 73static int sysrq_pressed; 74#endif 75 76struct hvc_struct { 77 spinlock_t lock; 78 int index; 79 struct tty_struct *tty; 80 unsigned int count; 81 int do_wakeup; 82 char *outbuf; 83 int outbuf_size; 84 int n_outbuf; 85 uint32_t vtermno; 86 struct hv_ops *ops; 87 int irq_requested; 88 int irq; 89 struct list_head next; 90 struct kobject kobj; /* ref count & hvc_struct lifetime */ 91}; 92 93/* dynamic list of hvc_struct instances */ 94static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs); 95 96/* 97 * Protect the list of hvc_struct instances from inserts and removals during 98 * list traversal. 99 */ 100static DEFINE_SPINLOCK(hvc_structs_lock); 101 102/* 103 * This value is used to assign a tty->index value to a hvc_struct based 104 * upon order of exposure via hvc_probe(), when we can not match it to 105 * a console candidate registered with hvc_instantiate(). 106 */ 107static int last_hvc = -1; 108 109/* 110 * Do not call this function with either the hvc_structs_lock or the hvc_struct 111 * lock held. If successful, this function increments the kobject reference 112 * count against the target hvc_struct so it should be released when finished. 113 */ 114static struct hvc_struct *hvc_get_by_index(int index) 115{ 116 struct hvc_struct *hp; 117 unsigned long flags; 118 119 spin_lock(&hvc_structs_lock); 120 121 list_for_each_entry(hp, &hvc_structs, next) { 122 spin_lock_irqsave(&hp->lock, flags); 123 if (hp->index == index) { 124 kobject_get(&hp->kobj); 125 spin_unlock_irqrestore(&hp->lock, flags); 126 spin_unlock(&hvc_structs_lock); 127 return hp; 128 } 129 spin_unlock_irqrestore(&hp->lock, flags); 130 } 131 hp = NULL; 132 133 spin_unlock(&hvc_structs_lock); 134 return hp; 135} 136 137 138/* 139 * Initial console vtermnos for console API usage prior to full console 140 * initialization. Any vty adapter outside this range will not have usable 141 * console interfaces but can still be used as a tty device. This has to be 142 * static because kmalloc will not work during early console init. 143 */ 144static struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES]; 145static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] = 146 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1}; 147 148/* 149 * Console APIs, NOT TTY. These APIs are available immediately when 150 * hvc_console_setup() finds adapters. 151 */ 152 153static void hvc_console_print(struct console *co, const char *b, 154 unsigned count) 155{ 156 char c[N_OUTBUF] __ALIGNED__; 157 unsigned i = 0, n = 0; 158 int r, donecr = 0, index = co->index; 159 160 /* Console access attempt outside of acceptable console range. */ 161 if (index >= MAX_NR_HVC_CONSOLES) 162 return; 163 164 /* This console adapter was removed so it is not usable. */ 165 if (vtermnos[index] < 0) 166 return; 167 168 while (count > 0 || i > 0) { 169 if (count > 0 && i < sizeof(c)) { 170 if (b[n] == '\n' && !donecr) { 171 c[i++] = '\r'; 172 donecr = 1; 173 } else { 174 c[i++] = b[n++]; 175 donecr = 0; 176 --count; 177 } 178 } else { 179 r = cons_ops[index]->put_chars(vtermnos[index], c, i); 180 if (r < 0) { 181 /* throw away chars on error */ 182 i = 0; 183 } else if (r > 0) { 184 i -= r; 185 if (i > 0) 186 memmove(c, c+r, i); 187 } 188 } 189 } 190} 191 192static struct tty_driver *hvc_console_device(struct console *c, int *index) 193{ 194 if (vtermnos[c->index] == -1) 195 return NULL; 196 197 *index = c->index; 198 return hvc_driver; 199} 200 201static int __init hvc_console_setup(struct console *co, char *options) 202{ 203 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES) 204 return -ENODEV; 205 206 if (vtermnos[co->index] == -1) 207 return -ENODEV; 208 209 return 0; 210} 211 212static struct console hvc_con_driver = { 213 .name = "hvc", 214 .write = hvc_console_print, 215 .device = hvc_console_device, 216 .setup = hvc_console_setup, 217 .flags = CON_PRINTBUFFER, 218 .index = -1, 219}; 220 221/* 222 * Early console initialization. Precedes driver initialization. 223 * 224 * (1) we are first, and the user specified another driver 225 * -- index will remain -1 226 * (2) we are first and the user specified no driver 227 * -- index will be set to 0, then we will fail setup. 228 * (3) we are first and the user specified our driver 229 * -- index will be set to user specified driver, and we will fail 230 * (4) we are after driver, and this initcall will register us 231 * -- if the user didn't specify a driver then the console will match 232 * 233 * Note that for cases 2 and 3, we will match later when the io driver 234 * calls hvc_instantiate() and call register again. 235 */ 236static int __init hvc_console_init(void) 237{ 238 register_console(&hvc_con_driver); 239 return 0; 240} 241console_initcall(hvc_console_init); 242 243/* 244 * hvc_instantiate() is an early console discovery method which locates 245 * consoles * prior to the vio subsystem discovering them. Hotplugged 246 * vty adapters do NOT get an hvc_instantiate() callback since they 247 * appear after early console init. 248 */ 249int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops) 250{ 251 struct hvc_struct *hp; 252 253 if (index < 0 || index >= MAX_NR_HVC_CONSOLES) 254 return -1; 255 256 if (vtermnos[index] != -1) 257 return -1; 258 259 /* make sure no no tty has been registered in this index */ 260 hp = hvc_get_by_index(index); 261 if (hp) { 262 kobject_put(&hp->kobj); 263 return -1; 264 } 265 266 vtermnos[index] = vtermno; 267 cons_ops[index] = ops; 268 269 /* reserve all indices up to and including this index */ 270 if (last_hvc < index) 271 last_hvc = index; 272 273 /* if this index is what the user requested, then register 274 * now (setup won't fail at this point). It's ok to just 275 * call register again if previously .setup failed. 276 */ 277 if (index == hvc_con_driver.index) 278 register_console(&hvc_con_driver); 279 280 return 0; 281} 282 283/* Wake the sleeping khvcd */ 284static void hvc_kick(void) 285{ 286 hvc_kicked = 1; 287 wake_up_process(hvc_task); 288} 289 290static int hvc_poll(struct hvc_struct *hp); 291 292/* 293 * NOTE: This API isn't used if the console adapter doesn't support interrupts. 294 * In this case the console is poll driven. 295 */ 296static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance) 297{ 298 /* if hvc_poll request a repoll, then kick the hvcd thread */ 299 if (hvc_poll(dev_instance)) 300 hvc_kick(); 301 return IRQ_HANDLED; 302} 303 304static void hvc_unthrottle(struct tty_struct *tty) 305{ 306 hvc_kick(); 307} 308 309/* 310 * The TTY interface won't be used until after the vio layer has exposed the vty 311 * adapter to the kernel. 312 */ 313static int hvc_open(struct tty_struct *tty, struct file * filp) 314{ 315 struct hvc_struct *hp; 316 unsigned long flags; 317 int irq = 0; 318 int rc = 0; 319 struct kobject *kobjp; 320 321 /* Auto increments kobject reference if found. */ 322 if (!(hp = hvc_get_by_index(tty->index))) 323 return -ENODEV; 324 325 spin_lock_irqsave(&hp->lock, flags); 326 /* Check and then increment for fast path open. */ 327 if (hp->count++ > 0) { 328 spin_unlock_irqrestore(&hp->lock, flags); 329 hvc_kick(); 330 return 0; 331 } /* else count == 0 */ 332 333 tty->driver_data = hp; 334 tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */ 335 336 hp->tty = tty; 337 /* Save for request_irq outside of spin_lock. */ 338 irq = hp->irq; 339 if (irq) 340 hp->irq_requested = 1; 341 342 kobjp = &hp->kobj; 343 344 spin_unlock_irqrestore(&hp->lock, flags); 345 /* check error, fallback to non-irq */ 346 if (irq) 347 rc = request_irq(irq, hvc_handle_interrupt, IRQF_DISABLED, "hvc_console", hp); 348 349 /* 350 * If the request_irq() fails and we return an error. The tty layer 351 * will call hvc_close() after a failed open but we don't want to clean 352 * up there so we'll clean up here and clear out the previously set 353 * tty fields and return the kobject reference. 354 */ 355 if (rc) { 356 spin_lock_irqsave(&hp->lock, flags); 357 hp->tty = NULL; 358 hp->irq_requested = 0; 359 spin_unlock_irqrestore(&hp->lock, flags); 360 tty->driver_data = NULL; 361 kobject_put(kobjp); 362 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc); 363 } 364 /* Force wakeup of the polling thread */ 365 hvc_kick(); 366 367 return rc; 368} 369 370static void hvc_close(struct tty_struct *tty, struct file * filp) 371{ 372 struct hvc_struct *hp; 373 struct kobject *kobjp; 374 int irq = 0; 375 unsigned long flags; 376 377 if (tty_hung_up_p(filp)) 378 return; 379 380 /* 381 * No driver_data means that this close was issued after a failed 382 * hvc_open by the tty layer's release_dev() function and we can just 383 * exit cleanly because the kobject reference wasn't made. 384 */ 385 if (!tty->driver_data) 386 return; 387 388 hp = tty->driver_data; 389 spin_lock_irqsave(&hp->lock, flags); 390 391 kobjp = &hp->kobj; 392 if (--hp->count == 0) { 393 if (hp->irq_requested) 394 irq = hp->irq; 395 hp->irq_requested = 0; 396 397 /* We are done with the tty pointer now. */ 398 hp->tty = NULL; 399 spin_unlock_irqrestore(&hp->lock, flags); 400 401 /* 402 * Chain calls chars_in_buffer() and returns immediately if 403 * there is no buffered data otherwise sleeps on a wait queue 404 * waking periodically to check chars_in_buffer(). 405 */ 406 tty_wait_until_sent(tty, HVC_CLOSE_WAIT); 407 408 if (irq) 409 free_irq(irq, hp); 410 411 } else { 412 if (hp->count < 0) 413 printk(KERN_ERR "hvc_close %X: oops, count is %d\n", 414 hp->vtermno, hp->count); 415 spin_unlock_irqrestore(&hp->lock, flags); 416 } 417 418 kobject_put(kobjp); 419} 420 421static void hvc_hangup(struct tty_struct *tty) 422{ 423 struct hvc_struct *hp = tty->driver_data; 424 unsigned long flags; 425 int irq = 0; 426 int temp_open_count; 427 struct kobject *kobjp; 428 429 if (!hp) 430 return; 431 432 spin_lock_irqsave(&hp->lock, flags); 433 434 /* 435 * The N_TTY line discipline has problems such that in a close vs 436 * open->hangup case this can be called after the final close so prevent 437 * that from happening for now. 438 */ 439 if (hp->count <= 0) { 440 spin_unlock_irqrestore(&hp->lock, flags); 441 return; 442 } 443 444 kobjp = &hp->kobj; 445 temp_open_count = hp->count; 446 hp->count = 0; 447 hp->n_outbuf = 0; 448 hp->tty = NULL; 449 if (hp->irq_requested) 450 /* Saved for use outside of spin_lock. */ 451 irq = hp->irq; 452 hp->irq_requested = 0; 453 spin_unlock_irqrestore(&hp->lock, flags); 454 if (irq) 455 free_irq(irq, hp); 456 while(temp_open_count) { 457 --temp_open_count; 458 kobject_put(kobjp); 459 } 460} 461 462/* 463 * Push buffered characters whether they were just recently buffered or waiting 464 * on a blocked hypervisor. Call this function with hp->lock held. 465 */ 466static void hvc_push(struct hvc_struct *hp) 467{ 468 int n; 469 470 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf); 471 if (n <= 0) { 472 if (n == 0) { 473 hp->do_wakeup = 1; 474 return; 475 } 476 /* throw away output on error; this happens when 477 there is no session connected to the vterm. */ 478 hp->n_outbuf = 0; 479 } else 480 hp->n_outbuf -= n; 481 if (hp->n_outbuf > 0) 482 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf); 483 else 484 hp->do_wakeup = 1; 485} 486 487static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count) 488{ 489 struct hvc_struct *hp = tty->driver_data; 490 unsigned long flags; 491 int rsize, written = 0; 492 493 /* This write was probably executed during a tty close. */ 494 if (!hp) 495 return -EPIPE; 496 497 if (hp->count <= 0) 498 return -EIO; 499 500 spin_lock_irqsave(&hp->lock, flags); 501 502 /* Push pending writes */ 503 if (hp->n_outbuf > 0) 504 hvc_push(hp); 505 506 while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) { 507 if (rsize > count) 508 rsize = count; 509 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize); 510 count -= rsize; 511 buf += rsize; 512 hp->n_outbuf += rsize; 513 written += rsize; 514 hvc_push(hp); 515 } 516 spin_unlock_irqrestore(&hp->lock, flags); 517 518 /* 519 * Racy, but harmless, kick thread if there is still pending data. 520 */ 521 if (hp->n_outbuf) 522 hvc_kick(); 523 524 return written; 525} 526 527/* 528 * This is actually a contract between the driver and the tty layer outlining 529 * how much write room the driver can guarantee will be sent OR BUFFERED. This 530 * driver MUST honor the return value. 531 */ 532static int hvc_write_room(struct tty_struct *tty) 533{ 534 struct hvc_struct *hp = tty->driver_data; 535 536 if (!hp) 537 return -1; 538 539 return hp->outbuf_size - hp->n_outbuf; 540} 541 542static int hvc_chars_in_buffer(struct tty_struct *tty) 543{ 544 struct hvc_struct *hp = tty->driver_data; 545 546 if (!hp) 547 return -1; 548 return hp->n_outbuf; 549} 550 551/* 552 * timeout will vary between the MIN and MAX values defined here. By default 553 * and during console activity we will use a default MIN_TIMEOUT of 10. When 554 * the console is idle, we increase the timeout value on each pass through 555 * msleep until we reach the max. This may be noticeable as a brief (average 556 * one second) delay on the console before the console responds to input when 557 * there has been no input for some time. 558 */ 559#define MIN_TIMEOUT (10) 560#define MAX_TIMEOUT (2000) 561static u32 timeout = MIN_TIMEOUT; 562 563#define HVC_POLL_READ 0x00000001 564#define HVC_POLL_WRITE 0x00000002 565 566static int hvc_poll(struct hvc_struct *hp) 567{ 568 struct tty_struct *tty; 569 int i, n, poll_mask = 0; 570 char buf[N_INBUF] __ALIGNED__; 571 unsigned long flags; 572 int read_total = 0; 573 574 spin_lock_irqsave(&hp->lock, flags); 575 576 /* Push pending writes */ 577 if (hp->n_outbuf > 0) 578 hvc_push(hp); 579 580 /* Reschedule us if still some write pending */ 581 if (hp->n_outbuf > 0) 582 poll_mask |= HVC_POLL_WRITE; 583 584 /* No tty attached, just skip */ 585 tty = hp->tty; 586 if (tty == NULL) 587 goto bail; 588 589 /* Now check if we can get data (are we throttled ?) */ 590 if (test_bit(TTY_THROTTLED, &tty->flags)) 591 goto throttled; 592 593 /* If we aren't interrupt driven and aren't throttled, we always 594 * request a reschedule 595 */ 596 if (hp->irq == 0) 597 poll_mask |= HVC_POLL_READ; 598 599 /* Read data if any */ 600 for (;;) { 601 int count = tty_buffer_request_room(tty, N_INBUF); 602 603 /* If flip is full, just reschedule a later read */ 604 if (count == 0) { 605 poll_mask |= HVC_POLL_READ; 606 break; 607 } 608 609 n = hp->ops->get_chars(hp->vtermno, buf, count); 610 if (n <= 0) { 611 /* Hangup the tty when disconnected from host */ 612 if (n == -EPIPE) { 613 spin_unlock_irqrestore(&hp->lock, flags); 614 tty_hangup(tty); 615 spin_lock_irqsave(&hp->lock, flags); 616 } else if ( n == -EAGAIN ) { 617 /* 618 * Some back-ends can only ensure a certain min 619 * num of bytes read, which may be > 'count'. 620 * Let the tty clear the flip buff to make room. 621 */ 622 poll_mask |= HVC_POLL_READ; 623 } 624 break; 625 } 626 for (i = 0; i < n; ++i) { 627#ifdef CONFIG_MAGIC_SYSRQ 628 if (hp->index == hvc_con_driver.index) { 629 /* Handle the SysRq Hack */ 630 if (buf[i] == '\x0f') { /* ^O */ 631 sysrq_pressed = 1; 632 continue; 633 } else if (sysrq_pressed) { 634 handle_sysrq(buf[i], tty); 635 sysrq_pressed = 0; 636 continue; 637 } 638 } 639#endif /* CONFIG_MAGIC_SYSRQ */ 640 tty_insert_flip_char(tty, buf[i], 0); 641 } 642 643 read_total += n; 644 } 645 throttled: 646 /* Wakeup write queue if necessary */ 647 if (hp->do_wakeup) { 648 hp->do_wakeup = 0; 649 tty_wakeup(tty); 650 } 651 bail: 652 spin_unlock_irqrestore(&hp->lock, flags); 653 654 if (read_total) { 655 /* Activity is occurring, so reset the polling backoff value to 656 a minimum for performance. */ 657 timeout = MIN_TIMEOUT; 658 659 tty_flip_buffer_push(tty); 660 } 661 662 return poll_mask; 663} 664 665#if defined(CONFIG_XMON) && defined(CONFIG_SMP) 666extern cpumask_t cpus_in_xmon; 667#else 668static const cpumask_t cpus_in_xmon = CPU_MASK_NONE; 669#endif 670 671/* 672 * This kthread is either polling or interrupt driven. This is determined by 673 * calling hvc_poll() who determines whether a console adapter support 674 * interrupts. 675 */ 676int khvcd(void *unused) 677{ 678 int poll_mask; 679 struct hvc_struct *hp; 680 681 __set_current_state(TASK_RUNNING); 682 do { 683 poll_mask = 0; 684 hvc_kicked = 0; 685 try_to_freeze(); 686 wmb(); 687 if (cpus_empty(cpus_in_xmon)) { 688 spin_lock(&hvc_structs_lock); 689 list_for_each_entry(hp, &hvc_structs, next) { 690 poll_mask |= hvc_poll(hp); 691 } 692 spin_unlock(&hvc_structs_lock); 693 } else 694 poll_mask |= HVC_POLL_READ; 695 if (hvc_kicked) 696 continue; 697 if (poll_mask & HVC_POLL_WRITE) { 698 yield(); 699 continue; 700 } 701 set_current_state(TASK_INTERRUPTIBLE); 702 if (!hvc_kicked) { 703 if (poll_mask == 0) 704 schedule(); 705 else { 706 if (timeout < MAX_TIMEOUT) 707 timeout += (timeout >> 6) + 1; 708 709 msleep_interruptible(timeout); 710 } 711 } 712 __set_current_state(TASK_RUNNING); 713 } while (!kthread_should_stop()); 714 715 return 0; 716} 717 718static const struct tty_operations hvc_ops = { 719 .open = hvc_open, 720 .close = hvc_close, 721 .write = hvc_write, 722 .hangup = hvc_hangup, 723 .unthrottle = hvc_unthrottle, 724 .write_room = hvc_write_room, 725 .chars_in_buffer = hvc_chars_in_buffer, 726}; 727 728/* callback when the kboject ref count reaches zero. */ 729static void destroy_hvc_struct(struct kobject *kobj) 730{ 731 struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj); 732 unsigned long flags; 733 734 spin_lock(&hvc_structs_lock); 735 736 spin_lock_irqsave(&hp->lock, flags); 737 list_del(&(hp->next)); 738 spin_unlock_irqrestore(&hp->lock, flags); 739 740 spin_unlock(&hvc_structs_lock); 741 742 kfree(hp); 743} 744 745static struct kobj_type hvc_kobj_type = { 746 .release = destroy_hvc_struct, 747}; 748 749struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int irq, 750 struct hv_ops *ops, int outbuf_size) 751{ 752 struct hvc_struct *hp; 753 int i; 754 755 hp = kmalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size, 756 GFP_KERNEL); 757 if (!hp) 758 return ERR_PTR(-ENOMEM); 759 760 memset(hp, 0x00, sizeof(*hp)); 761 762 hp->vtermno = vtermno; 763 hp->irq = irq; 764 hp->ops = ops; 765 hp->outbuf_size = outbuf_size; 766 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))]; 767 768 kobject_init(&hp->kobj); 769 hp->kobj.ktype = &hvc_kobj_type; 770 771 spin_lock_init(&hp->lock); 772 spin_lock(&hvc_structs_lock); 773 774 /* 775 * find index to use: 776 * see if this vterm id matches one registered for console. 777 */ 778 for (i=0; i < MAX_NR_HVC_CONSOLES; i++) 779 if (vtermnos[i] == hp->vtermno && 780 cons_ops[i] == hp->ops) 781 break; 782 783 /* no matching slot, just use a counter */ 784 if (i >= MAX_NR_HVC_CONSOLES) 785 i = ++last_hvc; 786 787 hp->index = i; 788 789 list_add_tail(&(hp->next), &hvc_structs); 790 spin_unlock(&hvc_structs_lock); 791 792 return hp; 793} 794 795int __devexit hvc_remove(struct hvc_struct *hp) 796{ 797 unsigned long flags; 798 struct kobject *kobjp; 799 struct tty_struct *tty; 800 801 spin_lock_irqsave(&hp->lock, flags); 802 tty = hp->tty; 803 kobjp = &hp->kobj; 804 805 if (hp->index < MAX_NR_HVC_CONSOLES) 806 vtermnos[hp->index] = -1; 807 808 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */ 809 810 spin_unlock_irqrestore(&hp->lock, flags); 811 812 /* 813 * We 'put' the instance that was grabbed when the kobject instance 814 * was initialized using kobject_init(). Let the last holder of this 815 * kobject cause it to be removed, which will probably be the tty_hangup 816 * below. 817 */ 818 kobject_put(kobjp); 819 820 /* 821 * This function call will auto chain call hvc_hangup. The tty should 822 * always be valid at this time unless a simultaneous tty close already 823 * cleaned up the hvc_struct. 824 */ 825 if (tty) 826 tty_hangup(tty); 827 return 0; 828} 829 830/* Driver initialization. Follow console initialization. This is where the TTY 831 * interfaces start to become available. */ 832static int __init hvc_init(void) 833{ 834 struct tty_driver *drv; 835 836 /* We need more than hvc_count adapters due to hotplug additions. */ 837 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS); 838 if (!drv) 839 return -ENOMEM; 840 841 drv->owner = THIS_MODULE; 842 drv->driver_name = "hvc"; 843 drv->name = "hvc"; 844 drv->major = HVC_MAJOR; 845 drv->minor_start = HVC_MINOR; 846 drv->type = TTY_DRIVER_TYPE_SYSTEM; 847 drv->init_termios = tty_std_termios; 848 drv->flags = TTY_DRIVER_REAL_RAW; 849 tty_set_operations(drv, &hvc_ops); 850 851 /* Always start the kthread because there can be hotplug vty adapters 852 * added later. */ 853 hvc_task = kthread_run(khvcd, NULL, "khvcd"); 854 if (IS_ERR(hvc_task)) { 855 panic("Couldn't create kthread for console.\n"); 856 put_tty_driver(drv); 857 return -EIO; 858 } 859 860 if (tty_register_driver(drv)) 861 panic("Couldn't register hvc console driver\n"); 862 863 mb(); 864 hvc_driver = drv; 865 return 0; 866} 867module_init(hvc_init); 868 869/* This isn't particularly necessary due to this being a console driver 870 * but it is nice to be thorough. 871 */ 872static void __exit hvc_exit(void) 873{ 874 kthread_stop(hvc_task); 875 876 tty_unregister_driver(hvc_driver); 877 /* return tty_struct instances allocated in hvc_init(). */ 878 put_tty_driver(hvc_driver); 879 unregister_console(&hvc_con_driver); 880} 881module_exit(hvc_exit); 882