drivers/s390/char/sclp_vt220.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * SCLP VT220 terminal driver.
   4  *
   5  * Copyright IBM Corp. 2003, 2009
   6  *
   7  * Author(s): Peter Oberparleiter <Peter.Oberparleiter@de.ibm.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/panic_notifier.h>
  13 #include <linux/list.h>
  14 #include <linux/wait.h>
  15 #include <linux/timer.h>
  16 #include <linux/kernel.h>
  17 #include <linux/sysrq.h>
  18 #include <linux/tty.h>
  19 #include <linux/tty_driver.h>
  20 #include <linux/tty_flip.h>
  21 #include <linux/errno.h>
  22 #include <linux/mm.h>
  23 #include <linux/major.h>
  24 #include <linux/console.h>
  25 #include <linux/kdev_t.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/init.h>
  28 #include <linux/reboot.h>
  29 #include <linux/slab.h>
  30
  31 #include <linux/uaccess.h>
  32 #include "sclp.h"
  33 #include "ctrlchar.h"
  34
  35 #define SCLP_VT220_MAJOR                TTY_MAJOR
  36 #define SCLP_VT220_MINOR                65
  37 #define SCLP_VT220_DRIVER_NAME          "sclp_vt220"
  38 #define SCLP_VT220_DEVICE_NAME          "ttysclp"
  39 #define SCLP_VT220_CONSOLE_NAME         "ttysclp"
  40 #define SCLP_VT220_CONSOLE_INDEX        0       /* console=ttysclp0 */
  41
  42 /* Representation of a single write request */
  43 struct sclp_vt220_request {
  44         struct list_head list;
  45         struct sclp_req sclp_req;
  46         int retry_count;
  47 };
  48
  49 /* VT220 SCCB */
  50 struct sclp_vt220_sccb {
  51         struct sccb_header header;
  52         struct evbuf_header evbuf;
  53 };
  54
  55 #define SCLP_VT220_MAX_CHARS_PER_BUFFER (PAGE_SIZE - \
  56                                          sizeof(struct sclp_vt220_request) - \
  57                                          sizeof(struct sclp_vt220_sccb))
  58
  59 /* Structures and data needed to register tty driver */
  60 static struct tty_driver *sclp_vt220_driver;
  61
  62 static struct tty_port sclp_vt220_port;
  63
  64 /* Lock to protect internal data from concurrent access */
  65 static DEFINE_SPINLOCK(sclp_vt220_lock);
  66
  67 /* List of empty pages to be used as write request buffers */
  68 static LIST_HEAD(sclp_vt220_empty);
  69
  70 /* List of pending requests */
  71 static LIST_HEAD(sclp_vt220_outqueue);
  72
  73 /* Flag that output queue is currently running */
  74 static int sclp_vt220_queue_running;
  75
  76 /* Timer used for delaying write requests to merge subsequent messages into
  77  * a single buffer */
  78 static struct timer_list sclp_vt220_timer;
  79
  80 /* Pointer to current request buffer which has been partially filled but not
  81  * yet sent */
  82 static struct sclp_vt220_request *sclp_vt220_current_request;
  83
  84 /* Number of characters in current request buffer */
  85 static int sclp_vt220_buffered_chars;
  86
  87 /* Counter controlling core driver initialization. */
  88 static int __initdata sclp_vt220_init_count;
  89
  90 /* Flag indicating that sclp_vt220_current_request should really
  91  * have been already queued but wasn't because the SCLP was processing
  92  * another buffer */
  93 static int sclp_vt220_flush_later;
  94
  95 static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
  96 static int __sclp_vt220_emit(struct sclp_vt220_request *request);
  97 static void sclp_vt220_emit_current(void);
  98
  99 /* Registration structure for SCLP output event buffers */
 100 static struct sclp_register sclp_vt220_register = {
 101         .send_mask              = EVTYP_VT220MSG_MASK,
 102 };
 103
 104 /* Registration structure for SCLP input event buffers */
 105 static struct sclp_register sclp_vt220_register_input = {
 106         .receive_mask           = EVTYP_VT220MSG_MASK,
 107         .receiver_fn            = sclp_vt220_receiver_fn,
 108 };
 109
 110
 111 /*
 112  * Put provided request buffer back into queue and check emit pending
 113  * buffers if necessary.
 114  */
 115 static void
 116 sclp_vt220_process_queue(struct sclp_vt220_request *request)
 117 {
 118         unsigned long flags;
 119         void *page;
 120
 121         do {
 122                 /* Put buffer back to list of empty buffers */
 123                 page = request->sclp_req.sccb;
 124                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 125                 /* Move request from outqueue to empty queue */
 126                 list_del(&request->list);
 127                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 128                 /* Check if there is a pending buffer on the out queue. */
 129                 request = NULL;
 130                 if (!list_empty(&sclp_vt220_outqueue))
 131                         request = list_entry(sclp_vt220_outqueue.next,
 132                                              struct sclp_vt220_request, list);
 133                 if (!request) {
 134                         sclp_vt220_queue_running = 0;
 135                         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 136                         break;
 137                 }
 138                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 139         } while (__sclp_vt220_emit(request));
 140         if (request == NULL && sclp_vt220_flush_later)
 141                 sclp_vt220_emit_current();
 142         tty_port_tty_wakeup(&sclp_vt220_port);
 143 }
 144
 145 #define SCLP_BUFFER_MAX_RETRY           1
 146
 147 /*
 148  * Callback through which the result of a write request is reported by the
 149  * SCLP.
 150  */
 151 static void
 152 sclp_vt220_callback(struct sclp_req *request, void *data)
 153 {
 154         struct sclp_vt220_request *vt220_request;
 155         struct sclp_vt220_sccb *sccb;
 156
 157         vt220_request = (struct sclp_vt220_request *) data;
 158         if (request->status == SCLP_REQ_FAILED) {
 159                 sclp_vt220_process_queue(vt220_request);
 160                 return;
 161         }
 162         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
 163
 164         /* Check SCLP response code and choose suitable action  */
 165         switch (sccb->header.response_code) {
 166         case 0x0020 :
 167                 break;
 168
 169         case 0x05f0: /* Target resource in improper state */
 170                 break;
 171
 172         case 0x0340: /* Contained SCLP equipment check */
 173                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 174                         break;
 175                 /* Remove processed buffers and requeue rest */
 176                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 177                         /* Not all buffers were processed */
 178                         sccb->header.response_code = 0x0000;
 179                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 180                         if (sclp_add_request(request) == 0)
 181                                 return;
 182                 }
 183                 break;
 184
 185         case 0x0040: /* SCLP equipment check */
 186                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 187                         break;
 188                 sccb->header.response_code = 0x0000;
 189                 vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 190                 if (sclp_add_request(request) == 0)
 191                         return;
 192                 break;
 193
 194         default:
 195                 break;
 196         }
 197         sclp_vt220_process_queue(vt220_request);
 198 }
 199
 200 /*
 201  * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
 202  * otherwise.
 203  */
 204 static int
 205 __sclp_vt220_emit(struct sclp_vt220_request *request)
 206 {
 207         request->sclp_req.command = SCLP_CMDW_WRITE_EVENT_DATA;
 208         request->sclp_req.status = SCLP_REQ_FILLED;
 209         request->sclp_req.callback = sclp_vt220_callback;
 210         request->sclp_req.callback_data = (void *) request;
 211
 212         return sclp_add_request(&request->sclp_req);
 213 }
 214
 215 /*
 216  * Queue and emit current request.
 217  */
 218 static void
 219 sclp_vt220_emit_current(void)
 220 {
 221         unsigned long flags;
 222         struct sclp_vt220_request *request;
 223         struct sclp_vt220_sccb *sccb;
 224
 225         spin_lock_irqsave(&sclp_vt220_lock, flags);
 226         if (sclp_vt220_current_request) {
 227                 sccb = (struct sclp_vt220_sccb *)
 228                                 sclp_vt220_current_request->sclp_req.sccb;
 229                 /* Only emit buffers with content */
 230                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 231                         list_add_tail(&sclp_vt220_current_request->list,
 232                                       &sclp_vt220_outqueue);
 233                         sclp_vt220_current_request = NULL;
 234                         if (timer_pending(&sclp_vt220_timer))
 235                                 del_timer(&sclp_vt220_timer);
 236                 }
 237                 sclp_vt220_flush_later = 0;
 238         }
 239         if (sclp_vt220_queue_running)
 240                 goto out_unlock;
 241         if (list_empty(&sclp_vt220_outqueue))
 242                 goto out_unlock;
 243         request = list_first_entry(&sclp_vt220_outqueue,
 244                                    struct sclp_vt220_request, list);
 245         sclp_vt220_queue_running = 1;
 246         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 247
 248         if (__sclp_vt220_emit(request))
 249                 sclp_vt220_process_queue(request);
 250         return;
 251 out_unlock:
 252         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 253 }
 254
 255 #define SCLP_NORMAL_WRITE       0x00
 256
 257 /*
 258  * Helper function to initialize a page with the sclp request structure.
 259  */
 260 static struct sclp_vt220_request *
 261 sclp_vt220_initialize_page(void *page)
 262 {
 263         struct sclp_vt220_request *request;
 264         struct sclp_vt220_sccb *sccb;
 265
 266         /* Place request structure at end of page */
 267         request = ((struct sclp_vt220_request *)
 268                         ((addr_t) page + PAGE_SIZE)) - 1;
 269         request->retry_count = 0;
 270         request->sclp_req.sccb = page;
 271         /* SCCB goes at start of page */
 272         sccb = (struct sclp_vt220_sccb *) page;
 273         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
 274         sccb->header.length = sizeof(struct sclp_vt220_sccb);
 275         sccb->header.function_code = SCLP_NORMAL_WRITE;
 276         sccb->header.response_code = 0x0000;
 277         sccb->evbuf.type = EVTYP_VT220MSG;
 278         sccb->evbuf.length = sizeof(struct evbuf_header);
 279
 280         return request;
 281 }
 282
 283 static inline unsigned int
 284 sclp_vt220_space_left(struct sclp_vt220_request *request)
 285 {
 286         struct sclp_vt220_sccb *sccb;
 287         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 288         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
 289                sccb->header.length;
 290 }
 291
 292 static inline unsigned int
 293 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
 294 {
 295         struct sclp_vt220_sccb *sccb;
 296         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 297         return sccb->evbuf.length - sizeof(struct evbuf_header);
 298 }
 299
 300 /*
 301  * Add msg to buffer associated with request. Return the number of characters
 302  * added.
 303  */
 304 static int
 305 sclp_vt220_add_msg(struct sclp_vt220_request *request,
 306                    const unsigned char *msg, int count, int convertlf)
 307 {
 308         struct sclp_vt220_sccb *sccb;
 309         void *buffer;
 310         unsigned char c;
 311         int from;
 312         int to;
 313
 314         if (count > sclp_vt220_space_left(request))
 315                 count = sclp_vt220_space_left(request);
 316         if (count <= 0)
 317                 return 0;
 318
 319         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 320         buffer = (void *) ((addr_t) sccb + sccb->header.length);
 321
 322         if (convertlf) {
 323                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
 324                 for (from=0, to=0;
 325                      (from < count) && (to < sclp_vt220_space_left(request));
 326                      from++) {
 327                         /* Retrieve character */
 328                         c = msg[from];
 329                         /* Perform conversion */
 330                         if (c == 0x0a) {
 331                                 if (to + 1 < sclp_vt220_space_left(request)) {
 332                                         ((unsigned char *) buffer)[to++] = c;
 333                                         ((unsigned char *) buffer)[to++] = 0x0d;
 334                                 } else
 335                                         break;
 336
 337                         } else
 338                                 ((unsigned char *) buffer)[to++] = c;
 339                 }
 340                 sccb->header.length += to;
 341                 sccb->evbuf.length += to;
 342                 return from;
 343         } else {
 344                 memcpy(buffer, (const void *) msg, count);
 345                 sccb->header.length += count;
 346                 sccb->evbuf.length += count;
 347                 return count;
 348         }
 349 }
 350
 351 /*
 352  * Emit buffer after having waited long enough for more data to arrive.
 353  */
 354 static void
 355 sclp_vt220_timeout(struct timer_list *unused)
 356 {
 357         sclp_vt220_emit_current();
 358 }
 359
 360 #define BUFFER_MAX_DELAY        HZ/20
 361
 362 /*
 363  * Drop oldest console buffer if sclp_con_drop is set
 364  */
 365 static int
 366 sclp_vt220_drop_buffer(void)
 367 {
 368         struct list_head *list;
 369         struct sclp_vt220_request *request;
 370         void *page;
 371
 372         if (!sclp_console_drop)
 373                 return 0;
 374         list = sclp_vt220_outqueue.next;
 375         if (sclp_vt220_queue_running)
 376                 /* The first element is in I/O */
 377                 list = list->next;
 378         if (list == &sclp_vt220_outqueue)
 379                 return 0;
 380         list_del(list);
 381         request = list_entry(list, struct sclp_vt220_request, list);
 382         page = request->sclp_req.sccb;
 383         list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 384         return 1;
 385 }
 386
 387 /*
 388  * Internal implementation of the write function. Write COUNT bytes of data
 389  * from memory at BUF
 390  * to the SCLP interface. In case that the data does not fit into the current
 391  * write buffer, emit the current one and allocate a new one. If there are no
 392  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 393  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 394  * otherwise the user has to explicitly call the flush function.
 395  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 396  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 397  * of bytes written.
 398  */
 399 static int
 400 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 401                    int convertlf, int may_fail)
 402 {
 403         unsigned long flags;
 404         void *page;
 405         int written;
 406         int overall_written;
 407
 408         if (count <= 0)
 409                 return 0;
 410         overall_written = 0;
 411         spin_lock_irqsave(&sclp_vt220_lock, flags);
 412         do {
 413                 /* Create an sclp output buffer if none exists yet */
 414                 if (sclp_vt220_current_request == NULL) {
 415                         if (list_empty(&sclp_vt220_empty))
 416                                 sclp_console_full++;
 417                         while (list_empty(&sclp_vt220_empty)) {
 418                                 if (may_fail)
 419                                         goto out;
 420                                 if (sclp_vt220_drop_buffer())
 421                                         break;
 422                                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 423
 424                                 sclp_sync_wait();
 425                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 426                         }
 427                         page = (void *) sclp_vt220_empty.next;
 428                         list_del((struct list_head *) page);
 429                         sclp_vt220_current_request =
 430                                 sclp_vt220_initialize_page(page);
 431                 }
 432                 /* Try to write the string to the current request buffer */
 433                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 434                                              buf, count, convertlf);
 435                 overall_written += written;
 436                 if (written == count)
 437                         break;
 438                 /*
 439                  * Not all characters could be written to the current
 440                  * output buffer. Emit the buffer, create a new buffer
 441                  * and then output the rest of the string.
 442                  */
 443                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 444                 sclp_vt220_emit_current();
 445                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 446                 buf += written;
 447                 count -= written;
 448         } while (count > 0);
 449         /* Setup timer to output current console buffer after some time */
 450         if (sclp_vt220_current_request != NULL &&
 451             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 452                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 453                 add_timer(&sclp_vt220_timer);
 454         }
 455 out:
 456         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 457         return overall_written;
 458 }
 459
 460 /*
 461  * This routine is called by the kernel to write a series of
 462  * characters to the tty device.  The characters may come from
 463  * user space or kernel space.  This routine will return the
 464  * number of characters actually accepted for writing.
 465  */
 466 static int
 467 sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
 468 {
 469         return __sclp_vt220_write(buf, count, 1, 0, 1);
 470 }
 471
 472 #define SCLP_VT220_SESSION_ENDED        0x01
 473 #define SCLP_VT220_SESSION_STARTED      0x80
 474 #define SCLP_VT220_SESSION_DATA         0x00
 475
 476 #ifdef CONFIG_MAGIC_SYSRQ
 477
 478 static int sysrq_pressed;
 479 static struct sysrq_work sysrq;
 480
 481 static void sclp_vt220_reset_session(void)
 482 {
 483         sysrq_pressed = 0;
 484 }
 485
 486 static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
 487 {
 488         int i;
 489
 490         for (i = 0; i < count; i++) {
 491                 /* Handle magic sys request */
 492                 if (buffer[i] == ('O' ^ 0100)) { /* CTRL-O */
 493                         /*
 494                          * If pressed again, reset sysrq_pressed
 495                          * and flip CTRL-O character
 496                          */
 497                         sysrq_pressed = !sysrq_pressed;
 498                         if (sysrq_pressed)
 499                                 continue;
 500                 } else if (sysrq_pressed) {
 501                         sysrq.key = buffer[i];
 502                         schedule_sysrq_work(&sysrq);
 503                         sysrq_pressed = 0;
 504                         continue;
 505                 }
 506                 tty_insert_flip_char(&sclp_vt220_port, buffer[i], 0);
 507         }
 508 }
 509
 510 #else
 511
 512 static void sclp_vt220_reset_session(void)
 513 {
 514 }
 515
 516 static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
 517 {
 518         tty_insert_flip_string(&sclp_vt220_port, buffer, count);
 519 }
 520
 521 #endif
 522
 523 /*
 524  * Called by the SCLP to report incoming event buffers.
 525  */
 526 static void
 527 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 528 {
 529         char *buffer;
 530         unsigned int count;
 531
 532         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 533         count = evbuf->length - sizeof(struct evbuf_header);
 534
 535         switch (*buffer) {
 536         case SCLP_VT220_SESSION_ENDED:
 537         case SCLP_VT220_SESSION_STARTED:
 538                 sclp_vt220_reset_session();
 539                 break;
 540         case SCLP_VT220_SESSION_DATA:
 541                 /* Send input to line discipline */
 542                 buffer++;
 543                 count--;
 544                 sclp_vt220_handle_input(buffer, count);
 545                 tty_flip_buffer_push(&sclp_vt220_port);
 546                 break;
 547         }
 548 }
 549
 550 /*
 551  * This routine is called when a particular tty device is opened.
 552  */
 553 static int
 554 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 555 {
 556         if (tty->count == 1) {
 557                 tty_port_tty_set(&sclp_vt220_port, tty);
 558                 if (!tty->winsize.ws_row && !tty->winsize.ws_col) {
 559                         tty->winsize.ws_row = 24;
 560                         tty->winsize.ws_col = 80;
 561                 }
 562         }
 563         return 0;
 564 }
 565
 566 /*
 567  * This routine is called when a particular tty device is closed.
 568  */
 569 static void
 570 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 571 {
 572         if (tty->count == 1)
 573                 tty_port_tty_set(&sclp_vt220_port, NULL);
 574 }
 575
 576 /*
 577  * This routine is called by the kernel to write a single
 578  * character to the tty device.  If the kernel uses this routine,
 579  * it must call the flush_chars() routine (if defined) when it is
 580  * done stuffing characters into the driver.
 581  */
 582 static int
 583 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 584 {
 585         return __sclp_vt220_write(&ch, 1, 0, 0, 1);
 586 }
 587
 588 /*
 589  * This routine is called by the kernel after it has written a
 590  * series of characters to the tty device using put_char().
 591  */
 592 static void
 593 sclp_vt220_flush_chars(struct tty_struct *tty)
 594 {
 595         if (!sclp_vt220_queue_running)
 596                 sclp_vt220_emit_current();
 597         else
 598                 sclp_vt220_flush_later = 1;
 599 }
 600
 601 /*
 602  * This routine returns the numbers of characters the tty driver
 603  * will accept for queuing to be written.  This number is subject
 604  * to change as output buffers get emptied, or if the output flow
 605  * control is acted.
 606  */
 607 static unsigned int
 608 sclp_vt220_write_room(struct tty_struct *tty)
 609 {
 610         unsigned long flags;
 611         struct list_head *l;
 612         unsigned int count;
 613
 614         spin_lock_irqsave(&sclp_vt220_lock, flags);
 615         count = 0;
 616         if (sclp_vt220_current_request != NULL)
 617                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 618         list_for_each(l, &sclp_vt220_empty)
 619                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 620         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 621         return count;
 622 }
 623
 624 /*
 625  * Return number of buffered chars.
 626  */
 627 static unsigned int
 628 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 629 {
 630         unsigned long flags;
 631         struct list_head *l;
 632         struct sclp_vt220_request *r;
 633         unsigned int count = 0;
 634
 635         spin_lock_irqsave(&sclp_vt220_lock, flags);
 636         if (sclp_vt220_current_request != NULL)
 637                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 638         list_for_each(l, &sclp_vt220_outqueue) {
 639                 r = list_entry(l, struct sclp_vt220_request, list);
 640                 count += sclp_vt220_chars_stored(r);
 641         }
 642         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 643         return count;
 644 }
 645
 646 /*
 647  * Pass on all buffers to the hardware. Return only when there are no more
 648  * buffers pending.
 649  */
 650 static void
 651 sclp_vt220_flush_buffer(struct tty_struct *tty)
 652 {
 653         sclp_vt220_emit_current();
 654 }
 655
 656 /* Release allocated pages. */
 657 static void __init __sclp_vt220_free_pages(void)
 658 {
 659         struct list_head *page, *p;
 660
 661         list_for_each_safe(page, p, &sclp_vt220_empty) {
 662                 list_del(page);
 663                 free_page((unsigned long) page);
 664         }
 665 }
 666
 667 /* Release memory and unregister from sclp core. Controlled by init counting -
 668  * only the last invoker will actually perform these actions. */
 669 static void __init __sclp_vt220_cleanup(void)
 670 {
 671         sclp_vt220_init_count--;
 672         if (sclp_vt220_init_count != 0)
 673                 return;
 674         sclp_unregister(&sclp_vt220_register);
 675         __sclp_vt220_free_pages();
 676         tty_port_destroy(&sclp_vt220_port);
 677 }
 678
 679 /* Allocate buffer pages and register with sclp core. Controlled by init
 680  * counting - only the first invoker will actually perform these actions. */
 681 static int __init __sclp_vt220_init(int num_pages)
 682 {
 683         void *page;
 684         int i;
 685         int rc;
 686
 687         sclp_vt220_init_count++;
 688         if (sclp_vt220_init_count != 1)
 689                 return 0;
 690         timer_setup(&sclp_vt220_timer, sclp_vt220_timeout, 0);
 691         tty_port_init(&sclp_vt220_port);
 692         sclp_vt220_current_request = NULL;
 693         sclp_vt220_buffered_chars = 0;
 694         sclp_vt220_flush_later = 0;
 695
 696         /* Allocate pages for output buffering */
 697         rc = -ENOMEM;
 698         for (i = 0; i < num_pages; i++) {
 699                 page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 700                 if (!page)
 701                         goto out;
 702                 list_add_tail(page, &sclp_vt220_empty);
 703         }
 704         rc = sclp_register(&sclp_vt220_register);
 705 out:
 706         if (rc) {
 707                 __sclp_vt220_free_pages();
 708                 sclp_vt220_init_count--;
 709                 tty_port_destroy(&sclp_vt220_port);
 710         }
 711         return rc;
 712 }
 713
 714 static const struct tty_operations sclp_vt220_ops = {
 715         .open = sclp_vt220_open,
 716         .close = sclp_vt220_close,
 717         .write = sclp_vt220_write,
 718         .put_char = sclp_vt220_put_char,
 719         .flush_chars = sclp_vt220_flush_chars,
 720         .write_room = sclp_vt220_write_room,
 721         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 722         .flush_buffer = sclp_vt220_flush_buffer,
 723 };
 724
 725 /*
 726  * Register driver with SCLP and Linux and initialize internal tty structures.
 727  */
 728 static int __init sclp_vt220_tty_init(void)
 729 {
 730         struct tty_driver *driver;
 731         int rc;
 732
 733         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 734          * symmetry between VM and LPAR systems regarding ttyS1. */
 735         driver = alloc_tty_driver(1);
 736         if (!driver)
 737                 return -ENOMEM;
 738         rc = __sclp_vt220_init(MAX_KMEM_PAGES);
 739         if (rc)
 740                 goto out_driver;
 741
 742         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 743         driver->name = SCLP_VT220_DEVICE_NAME;
 744         driver->major = SCLP_VT220_MAJOR;
 745         driver->minor_start = SCLP_VT220_MINOR;
 746         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 747         driver->subtype = SYSTEM_TYPE_TTY;
 748         driver->init_termios = tty_std_termios;
 749         driver->flags = TTY_DRIVER_REAL_RAW;
 750         tty_set_operations(driver, &sclp_vt220_ops);
 751         tty_port_link_device(&sclp_vt220_port, driver, 0);
 752
 753         rc = tty_register_driver(driver);
 754         if (rc)
 755                 goto out_init;
 756         rc = sclp_register(&sclp_vt220_register_input);
 757         if (rc)
 758                 goto out_reg;
 759         sclp_vt220_driver = driver;
 760         return 0;
 761
 762 out_reg:
 763         tty_unregister_driver(driver);
 764 out_init:
 765         __sclp_vt220_cleanup();
 766 out_driver:
 767         put_tty_driver(driver);
 768         return rc;
 769 }
 770 __initcall(sclp_vt220_tty_init);
 771
 772 static void __sclp_vt220_flush_buffer(void)
 773 {
 774         unsigned long flags;
 775
 776         sclp_vt220_emit_current();
 777         spin_lock_irqsave(&sclp_vt220_lock, flags);
 778         if (timer_pending(&sclp_vt220_timer))
 779                 del_timer(&sclp_vt220_timer);
 780         while (sclp_vt220_queue_running) {
 781                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 782                 sclp_sync_wait();
 783                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 784         }
 785         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 786 }
 787
 788 #ifdef CONFIG_SCLP_VT220_CONSOLE
 789
 790 static void
 791 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 792 {
 793         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1, 0);
 794 }
 795
 796 static struct tty_driver *
 797 sclp_vt220_con_device(struct console *c, int *index)
 798 {
 799         *index = 0;
 800         return sclp_vt220_driver;
 801 }
 802
 803 static int
 804 sclp_vt220_notify(struct notifier_block *self,
 805                           unsigned long event, void *data)
 806 {
 807         __sclp_vt220_flush_buffer();
 808         return NOTIFY_OK;
 809 }
 810
 811 static struct notifier_block on_panic_nb = {
 812         .notifier_call = sclp_vt220_notify,
 813         .priority = 1,
 814 };
 815
 816 static struct notifier_block on_reboot_nb = {
 817         .notifier_call = sclp_vt220_notify,
 818         .priority = 1,
 819 };
 820
 821 /* Structure needed to register with printk */
 822 static struct console sclp_vt220_console =
 823 {
 824         .name = SCLP_VT220_CONSOLE_NAME,
 825         .write = sclp_vt220_con_write,
 826         .device = sclp_vt220_con_device,
 827         .flags = CON_PRINTBUFFER,
 828         .index = SCLP_VT220_CONSOLE_INDEX
 829 };
 830
 831 static int __init
 832 sclp_vt220_con_init(void)
 833 {
 834         int rc;
 835
 836         rc = __sclp_vt220_init(sclp_console_pages);
 837         if (rc)
 838                 return rc;
 839         /* Attach linux console */
 840         atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
 841         register_reboot_notifier(&on_reboot_nb);
 842         register_console(&sclp_vt220_console);
 843         return 0;
 844 }
 845
 846 console_initcall(sclp_vt220_con_init);
 847 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 848