drivers/s390/char/sclp_vt220.c

   1 /*
   2  * SCLP VT220 terminal driver.
   3  *
   4  * Copyright IBM Corp. 2003, 2009
   5  *
   6  * Author(s): Peter Oberparleiter <Peter.Oberparleiter@de.ibm.com>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/list.h>
  12 #include <linux/wait.h>
  13 #include <linux/timer.h>
  14 #include <linux/kernel.h>
  15 #include <linux/tty.h>
  16 #include <linux/tty_driver.h>
  17 #include <linux/tty_flip.h>
  18 #include <linux/errno.h>
  19 #include <linux/mm.h>
  20 #include <linux/major.h>
  21 #include <linux/console.h>
  22 #include <linux/kdev_t.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/init.h>
  25 #include <linux/reboot.h>
  26 #include <linux/slab.h>
  27
  28 #include <asm/uaccess.h>
  29 #include "sclp.h"
  30
  31 #define SCLP_VT220_MAJOR                TTY_MAJOR
  32 #define SCLP_VT220_MINOR                65
  33 #define SCLP_VT220_DRIVER_NAME          "sclp_vt220"
  34 #define SCLP_VT220_DEVICE_NAME          "ttysclp"
  35 #define SCLP_VT220_CONSOLE_NAME         "ttyS"
  36 #define SCLP_VT220_CONSOLE_INDEX        1       /* console=ttyS1 */
  37
  38 /* Representation of a single write request */
  39 struct sclp_vt220_request {
  40         struct list_head list;
  41         struct sclp_req sclp_req;
  42         int retry_count;
  43 };
  44
  45 /* VT220 SCCB */
  46 struct sclp_vt220_sccb {
  47         struct sccb_header header;
  48         struct evbuf_header evbuf;
  49 };
  50
  51 #define SCLP_VT220_MAX_CHARS_PER_BUFFER (PAGE_SIZE - \
  52                                          sizeof(struct sclp_vt220_request) - \
  53                                          sizeof(struct sclp_vt220_sccb))
  54
  55 /* Structures and data needed to register tty driver */
  56 static struct tty_driver *sclp_vt220_driver;
  57
  58 static struct tty_port sclp_vt220_port;
  59
  60 /* Lock to protect internal data from concurrent access */
  61 static spinlock_t sclp_vt220_lock;
  62
  63 /* List of empty pages to be used as write request buffers */
  64 static struct list_head sclp_vt220_empty;
  65
  66 /* List of pending requests */
  67 static struct list_head sclp_vt220_outqueue;
  68
  69 /* Suspend mode flag */
  70 static int sclp_vt220_suspended;
  71
  72 /* Flag that output queue is currently running */
  73 static int sclp_vt220_queue_running;
  74
  75 /* Timer used for delaying write requests to merge subsequent messages into
  76  * a single buffer */
  77 static struct timer_list sclp_vt220_timer;
  78
  79 /* Pointer to current request buffer which has been partially filled but not
  80  * yet sent */
  81 static struct sclp_vt220_request *sclp_vt220_current_request;
  82
  83 /* Number of characters in current request buffer */
  84 static int sclp_vt220_buffered_chars;
  85
  86 /* Counter controlling core driver initialization. */
  87 static int __initdata sclp_vt220_init_count;
  88
  89 /* Flag indicating that sclp_vt220_current_request should really
  90  * have been already queued but wasn't because the SCLP was processing
  91  * another buffer */
  92 static int sclp_vt220_flush_later;
  93
  94 static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
  95 static void sclp_vt220_pm_event_fn(struct sclp_register *reg,
  96                                    enum sclp_pm_event sclp_pm_event);
  97 static int __sclp_vt220_emit(struct sclp_vt220_request *request);
  98 static void sclp_vt220_emit_current(void);
  99
 100 /* Registration structure for SCLP output event buffers */
 101 static struct sclp_register sclp_vt220_register = {
 102         .send_mask              = EVTYP_VT220MSG_MASK,
 103         .pm_event_fn            = sclp_vt220_pm_event_fn,
 104 };
 105
 106 /* Registration structure for SCLP input event buffers */
 107 static struct sclp_register sclp_vt220_register_input = {
 108         .receive_mask           = EVTYP_VT220MSG_MASK,
 109         .receiver_fn            = sclp_vt220_receiver_fn,
 110 };
 111
 112
 113 /*
 114  * Put provided request buffer back into queue and check emit pending
 115  * buffers if necessary.
 116  */
 117 static void
 118 sclp_vt220_process_queue(struct sclp_vt220_request *request)
 119 {
 120         unsigned long flags;
 121         void *page;
 122
 123         do {
 124                 /* Put buffer back to list of empty buffers */
 125                 page = request->sclp_req.sccb;
 126                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 127                 /* Move request from outqueue to empty queue */
 128                 list_del(&request->list);
 129                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 130                 /* Check if there is a pending buffer on the out queue. */
 131                 request = NULL;
 132                 if (!list_empty(&sclp_vt220_outqueue))
 133                         request = list_entry(sclp_vt220_outqueue.next,
 134                                              struct sclp_vt220_request, list);
 135                 if (!request || sclp_vt220_suspended) {
 136                         sclp_vt220_queue_running = 0;
 137                         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 138                         break;
 139                 }
 140                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 141         } while (__sclp_vt220_emit(request));
 142         if (request == NULL && sclp_vt220_flush_later)
 143                 sclp_vt220_emit_current();
 144         tty_port_tty_wakeup(&sclp_vt220_port);
 145 }
 146
 147 #define SCLP_BUFFER_MAX_RETRY           1
 148
 149 /*
 150  * Callback through which the result of a write request is reported by the
 151  * SCLP.
 152  */
 153 static void
 154 sclp_vt220_callback(struct sclp_req *request, void *data)
 155 {
 156         struct sclp_vt220_request *vt220_request;
 157         struct sclp_vt220_sccb *sccb;
 158
 159         vt220_request = (struct sclp_vt220_request *) data;
 160         if (request->status == SCLP_REQ_FAILED) {
 161                 sclp_vt220_process_queue(vt220_request);
 162                 return;
 163         }
 164         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
 165
 166         /* Check SCLP response code and choose suitable action  */
 167         switch (sccb->header.response_code) {
 168         case 0x0020 :
 169                 break;
 170
 171         case 0x05f0: /* Target resource in improper state */
 172                 break;
 173
 174         case 0x0340: /* Contained SCLP equipment check */
 175                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 176                         break;
 177                 /* Remove processed buffers and requeue rest */
 178                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 179                         /* Not all buffers were processed */
 180                         sccb->header.response_code = 0x0000;
 181                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 182                         if (sclp_add_request(request) == 0)
 183                                 return;
 184                 }
 185                 break;
 186
 187         case 0x0040: /* SCLP equipment check */
 188                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 189                         break;
 190                 sccb->header.response_code = 0x0000;
 191                 vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 192                 if (sclp_add_request(request) == 0)
 193                         return;
 194                 break;
 195
 196         default:
 197                 break;
 198         }
 199         sclp_vt220_process_queue(vt220_request);
 200 }
 201
 202 /*
 203  * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
 204  * otherwise.
 205  */
 206 static int
 207 __sclp_vt220_emit(struct sclp_vt220_request *request)
 208 {
 209         if (!(sclp_vt220_register.sclp_receive_mask & EVTYP_VT220MSG_MASK)) {
 210                 request->sclp_req.status = SCLP_REQ_FAILED;
 211                 return -EIO;
 212         }
 213         request->sclp_req.command = SCLP_CMDW_WRITE_EVENT_DATA;
 214         request->sclp_req.status = SCLP_REQ_FILLED;
 215         request->sclp_req.callback = sclp_vt220_callback;
 216         request->sclp_req.callback_data = (void *) request;
 217
 218         return sclp_add_request(&request->sclp_req);
 219 }
 220
 221 /*
 222  * Queue and emit current request.
 223  */
 224 static void
 225 sclp_vt220_emit_current(void)
 226 {
 227         unsigned long flags;
 228         struct sclp_vt220_request *request;
 229         struct sclp_vt220_sccb *sccb;
 230
 231         spin_lock_irqsave(&sclp_vt220_lock, flags);
 232         if (sclp_vt220_current_request) {
 233                 sccb = (struct sclp_vt220_sccb *)
 234                                 sclp_vt220_current_request->sclp_req.sccb;
 235                 /* Only emit buffers with content */
 236                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 237                         list_add_tail(&sclp_vt220_current_request->list,
 238                                       &sclp_vt220_outqueue);
 239                         sclp_vt220_current_request = NULL;
 240                         if (timer_pending(&sclp_vt220_timer))
 241                                 del_timer(&sclp_vt220_timer);
 242                 }
 243                 sclp_vt220_flush_later = 0;
 244         }
 245         if (sclp_vt220_queue_running || sclp_vt220_suspended)
 246                 goto out_unlock;
 247         if (list_empty(&sclp_vt220_outqueue))
 248                 goto out_unlock;
 249         request = list_first_entry(&sclp_vt220_outqueue,
 250                                    struct sclp_vt220_request, list);
 251         sclp_vt220_queue_running = 1;
 252         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 253
 254         if (__sclp_vt220_emit(request))
 255                 sclp_vt220_process_queue(request);
 256         return;
 257 out_unlock:
 258         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 259 }
 260
 261 #define SCLP_NORMAL_WRITE       0x00
 262
 263 /*
 264  * Helper function to initialize a page with the sclp request structure.
 265  */
 266 static struct sclp_vt220_request *
 267 sclp_vt220_initialize_page(void *page)
 268 {
 269         struct sclp_vt220_request *request;
 270         struct sclp_vt220_sccb *sccb;
 271
 272         /* Place request structure at end of page */
 273         request = ((struct sclp_vt220_request *)
 274                         ((addr_t) page + PAGE_SIZE)) - 1;
 275         request->retry_count = 0;
 276         request->sclp_req.sccb = page;
 277         /* SCCB goes at start of page */
 278         sccb = (struct sclp_vt220_sccb *) page;
 279         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
 280         sccb->header.length = sizeof(struct sclp_vt220_sccb);
 281         sccb->header.function_code = SCLP_NORMAL_WRITE;
 282         sccb->header.response_code = 0x0000;
 283         sccb->evbuf.type = EVTYP_VT220MSG;
 284         sccb->evbuf.length = sizeof(struct evbuf_header);
 285
 286         return request;
 287 }
 288
 289 static inline unsigned int
 290 sclp_vt220_space_left(struct sclp_vt220_request *request)
 291 {
 292         struct sclp_vt220_sccb *sccb;
 293         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 294         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
 295                sccb->header.length;
 296 }
 297
 298 static inline unsigned int
 299 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
 300 {
 301         struct sclp_vt220_sccb *sccb;
 302         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 303         return sccb->evbuf.length - sizeof(struct evbuf_header);
 304 }
 305
 306 /*
 307  * Add msg to buffer associated with request. Return the number of characters
 308  * added.
 309  */
 310 static int
 311 sclp_vt220_add_msg(struct sclp_vt220_request *request,
 312                    const unsigned char *msg, int count, int convertlf)
 313 {
 314         struct sclp_vt220_sccb *sccb;
 315         void *buffer;
 316         unsigned char c;
 317         int from;
 318         int to;
 319
 320         if (count > sclp_vt220_space_left(request))
 321                 count = sclp_vt220_space_left(request);
 322         if (count <= 0)
 323                 return 0;
 324
 325         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 326         buffer = (void *) ((addr_t) sccb + sccb->header.length);
 327
 328         if (convertlf) {
 329                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
 330                 for (from=0, to=0;
 331                      (from < count) && (to < sclp_vt220_space_left(request));
 332                      from++) {
 333                         /* Retrieve character */
 334                         c = msg[from];
 335                         /* Perform conversion */
 336                         if (c == 0x0a) {
 337                                 if (to + 1 < sclp_vt220_space_left(request)) {
 338                                         ((unsigned char *) buffer)[to++] = c;
 339                                         ((unsigned char *) buffer)[to++] = 0x0d;
 340                                 } else
 341                                         break;
 342
 343                         } else
 344                                 ((unsigned char *) buffer)[to++] = c;
 345                 }
 346                 sccb->header.length += to;
 347                 sccb->evbuf.length += to;
 348                 return from;
 349         } else {
 350                 memcpy(buffer, (const void *) msg, count);
 351                 sccb->header.length += count;
 352                 sccb->evbuf.length += count;
 353                 return count;
 354         }
 355 }
 356
 357 /*
 358  * Emit buffer after having waited long enough for more data to arrive.
 359  */
 360 static void
 361 sclp_vt220_timeout(unsigned long data)
 362 {
 363         sclp_vt220_emit_current();
 364 }
 365
 366 #define BUFFER_MAX_DELAY        HZ/20
 367
 368 /*
 369  * Drop oldest console buffer if sclp_con_drop is set
 370  */
 371 static int
 372 sclp_vt220_drop_buffer(void)
 373 {
 374         struct list_head *list;
 375         struct sclp_vt220_request *request;
 376         void *page;
 377
 378         if (!sclp_console_drop)
 379                 return 0;
 380         list = sclp_vt220_outqueue.next;
 381         if (sclp_vt220_queue_running)
 382                 /* The first element is in I/O */
 383                 list = list->next;
 384         if (list == &sclp_vt220_outqueue)
 385                 return 0;
 386         list_del(list);
 387         request = list_entry(list, struct sclp_vt220_request, list);
 388         page = request->sclp_req.sccb;
 389         list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 390         return 1;
 391 }
 392
 393 /*
 394  * Internal implementation of the write function. Write COUNT bytes of data
 395  * from memory at BUF
 396  * to the SCLP interface. In case that the data does not fit into the current
 397  * write buffer, emit the current one and allocate a new one. If there are no
 398  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 399  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 400  * otherwise the user has to explicitly call the flush function.
 401  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 402  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 403  * of bytes written.
 404  */
 405 static int
 406 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 407                    int convertlf, int may_fail)
 408 {
 409         unsigned long flags;
 410         void *page;
 411         int written;
 412         int overall_written;
 413
 414         if (count <= 0)
 415                 return 0;
 416         overall_written = 0;
 417         spin_lock_irqsave(&sclp_vt220_lock, flags);
 418         do {
 419                 /* Create an sclp output buffer if none exists yet */
 420                 if (sclp_vt220_current_request == NULL) {
 421                         if (list_empty(&sclp_vt220_empty))
 422                                 sclp_console_full++;
 423                         while (list_empty(&sclp_vt220_empty)) {
 424                                 if (may_fail || sclp_vt220_suspended)
 425                                         goto out;
 426                                 if (sclp_vt220_drop_buffer())
 427                                         break;
 428                                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 429
 430                                 sclp_sync_wait();
 431                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 432                         }
 433                         page = (void *) sclp_vt220_empty.next;
 434                         list_del((struct list_head *) page);
 435                         sclp_vt220_current_request =
 436                                 sclp_vt220_initialize_page(page);
 437                 }
 438                 /* Try to write the string to the current request buffer */
 439                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 440                                              buf, count, convertlf);
 441                 overall_written += written;
 442                 if (written == count)
 443                         break;
 444                 /*
 445                  * Not all characters could be written to the current
 446                  * output buffer. Emit the buffer, create a new buffer
 447                  * and then output the rest of the string.
 448                  */
 449                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 450                 sclp_vt220_emit_current();
 451                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 452                 buf += written;
 453                 count -= written;
 454         } while (count > 0);
 455         /* Setup timer to output current console buffer after some time */
 456         if (sclp_vt220_current_request != NULL &&
 457             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 458                 sclp_vt220_timer.function = sclp_vt220_timeout;
 459                 sclp_vt220_timer.data = 0UL;
 460                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 461                 add_timer(&sclp_vt220_timer);
 462         }
 463 out:
 464         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 465         return overall_written;
 466 }
 467
 468 /*
 469  * This routine is called by the kernel to write a series of
 470  * characters to the tty device.  The characters may come from
 471  * user space or kernel space.  This routine will return the
 472  * number of characters actually accepted for writing.
 473  */
 474 static int
 475 sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
 476 {
 477         return __sclp_vt220_write(buf, count, 1, 0, 1);
 478 }
 479
 480 #define SCLP_VT220_SESSION_ENDED        0x01
 481 #define SCLP_VT220_SESSION_STARTED      0x80
 482 #define SCLP_VT220_SESSION_DATA         0x00
 483
 484 /*
 485  * Called by the SCLP to report incoming event buffers.
 486  */
 487 static void
 488 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 489 {
 490         char *buffer;
 491         unsigned int count;
 492
 493         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 494         count = evbuf->length - sizeof(struct evbuf_header);
 495
 496         switch (*buffer) {
 497         case SCLP_VT220_SESSION_ENDED:
 498         case SCLP_VT220_SESSION_STARTED:
 499                 break;
 500         case SCLP_VT220_SESSION_DATA:
 501                 /* Send input to line discipline */
 502                 buffer++;
 503                 count--;
 504                 tty_insert_flip_string(&sclp_vt220_port, buffer, count);
 505                 tty_flip_buffer_push(&sclp_vt220_port);
 506                 break;
 507         }
 508 }
 509
 510 /*
 511  * This routine is called when a particular tty device is opened.
 512  */
 513 static int
 514 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 515 {
 516         if (tty->count == 1) {
 517                 tty_port_tty_set(&sclp_vt220_port, tty);
 518                 sclp_vt220_port.low_latency = 0;
 519                 if (!tty->winsize.ws_row && !tty->winsize.ws_col) {
 520                         tty->winsize.ws_row = 24;
 521                         tty->winsize.ws_col = 80;
 522                 }
 523         }
 524         return 0;
 525 }
 526
 527 /*
 528  * This routine is called when a particular tty device is closed.
 529  */
 530 static void
 531 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 532 {
 533         if (tty->count == 1)
 534                 tty_port_tty_set(&sclp_vt220_port, NULL);
 535 }
 536
 537 /*
 538  * This routine is called by the kernel to write a single
 539  * character to the tty device.  If the kernel uses this routine,
 540  * it must call the flush_chars() routine (if defined) when it is
 541  * done stuffing characters into the driver.
 542  */
 543 static int
 544 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 545 {
 546         return __sclp_vt220_write(&ch, 1, 0, 0, 1);
 547 }
 548
 549 /*
 550  * This routine is called by the kernel after it has written a
 551  * series of characters to the tty device using put_char().
 552  */
 553 static void
 554 sclp_vt220_flush_chars(struct tty_struct *tty)
 555 {
 556         if (!sclp_vt220_queue_running)
 557                 sclp_vt220_emit_current();
 558         else
 559                 sclp_vt220_flush_later = 1;
 560 }
 561
 562 /*
 563  * This routine returns the numbers of characters the tty driver
 564  * will accept for queuing to be written.  This number is subject
 565  * to change as output buffers get emptied, or if the output flow
 566  * control is acted.
 567  */
 568 static int
 569 sclp_vt220_write_room(struct tty_struct *tty)
 570 {
 571         unsigned long flags;
 572         struct list_head *l;
 573         int count;
 574
 575         spin_lock_irqsave(&sclp_vt220_lock, flags);
 576         count = 0;
 577         if (sclp_vt220_current_request != NULL)
 578                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 579         list_for_each(l, &sclp_vt220_empty)
 580                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 581         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 582         return count;
 583 }
 584
 585 /*
 586  * Return number of buffered chars.
 587  */
 588 static int
 589 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 590 {
 591         unsigned long flags;
 592         struct list_head *l;
 593         struct sclp_vt220_request *r;
 594         int count;
 595
 596         spin_lock_irqsave(&sclp_vt220_lock, flags);
 597         count = 0;
 598         if (sclp_vt220_current_request != NULL)
 599                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 600         list_for_each(l, &sclp_vt220_outqueue) {
 601                 r = list_entry(l, struct sclp_vt220_request, list);
 602                 count += sclp_vt220_chars_stored(r);
 603         }
 604         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 605         return count;
 606 }
 607
 608 /*
 609  * Pass on all buffers to the hardware. Return only when there are no more
 610  * buffers pending.
 611  */
 612 static void
 613 sclp_vt220_flush_buffer(struct tty_struct *tty)
 614 {
 615         sclp_vt220_emit_current();
 616 }
 617
 618 /* Release allocated pages. */
 619 static void __init __sclp_vt220_free_pages(void)
 620 {
 621         struct list_head *page, *p;
 622
 623         list_for_each_safe(page, p, &sclp_vt220_empty) {
 624                 list_del(page);
 625                 free_page((unsigned long) page);
 626         }
 627 }
 628
 629 /* Release memory and unregister from sclp core. Controlled by init counting -
 630  * only the last invoker will actually perform these actions. */
 631 static void __init __sclp_vt220_cleanup(void)
 632 {
 633         sclp_vt220_init_count--;
 634         if (sclp_vt220_init_count != 0)
 635                 return;
 636         sclp_unregister(&sclp_vt220_register);
 637         __sclp_vt220_free_pages();
 638         tty_port_destroy(&sclp_vt220_port);
 639 }
 640
 641 /* Allocate buffer pages and register with sclp core. Controlled by init
 642  * counting - only the first invoker will actually perform these actions. */
 643 static int __init __sclp_vt220_init(int num_pages)
 644 {
 645         void *page;
 646         int i;
 647         int rc;
 648
 649         sclp_vt220_init_count++;
 650         if (sclp_vt220_init_count != 1)
 651                 return 0;
 652         spin_lock_init(&sclp_vt220_lock);
 653         INIT_LIST_HEAD(&sclp_vt220_empty);
 654         INIT_LIST_HEAD(&sclp_vt220_outqueue);
 655         init_timer(&sclp_vt220_timer);
 656         tty_port_init(&sclp_vt220_port);
 657         sclp_vt220_current_request = NULL;
 658         sclp_vt220_buffered_chars = 0;
 659         sclp_vt220_flush_later = 0;
 660
 661         /* Allocate pages for output buffering */
 662         rc = -ENOMEM;
 663         for (i = 0; i < num_pages; i++) {
 664                 page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 665                 if (!page)
 666                         goto out;
 667                 list_add_tail(page, &sclp_vt220_empty);
 668         }
 669         rc = sclp_register(&sclp_vt220_register);
 670 out:
 671         if (rc) {
 672                 __sclp_vt220_free_pages();
 673                 sclp_vt220_init_count--;
 674                 tty_port_destroy(&sclp_vt220_port);
 675         }
 676         return rc;
 677 }
 678
 679 static const struct tty_operations sclp_vt220_ops = {
 680         .open = sclp_vt220_open,
 681         .close = sclp_vt220_close,
 682         .write = sclp_vt220_write,
 683         .put_char = sclp_vt220_put_char,
 684         .flush_chars = sclp_vt220_flush_chars,
 685         .write_room = sclp_vt220_write_room,
 686         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 687         .flush_buffer = sclp_vt220_flush_buffer,
 688 };
 689
 690 /*
 691  * Register driver with SCLP and Linux and initialize internal tty structures.
 692  */
 693 static int __init sclp_vt220_tty_init(void)
 694 {
 695         struct tty_driver *driver;
 696         int rc;
 697
 698         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 699          * symmetry between VM and LPAR systems regarding ttyS1. */
 700         driver = alloc_tty_driver(1);
 701         if (!driver)
 702                 return -ENOMEM;
 703         rc = __sclp_vt220_init(MAX_KMEM_PAGES);
 704         if (rc)
 705                 goto out_driver;
 706
 707         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 708         driver->name = SCLP_VT220_DEVICE_NAME;
 709         driver->major = SCLP_VT220_MAJOR;
 710         driver->minor_start = SCLP_VT220_MINOR;
 711         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 712         driver->subtype = SYSTEM_TYPE_TTY;
 713         driver->init_termios = tty_std_termios;
 714         driver->flags = TTY_DRIVER_REAL_RAW;
 715         tty_set_operations(driver, &sclp_vt220_ops);
 716         tty_port_link_device(&sclp_vt220_port, driver, 0);
 717
 718         rc = tty_register_driver(driver);
 719         if (rc)
 720                 goto out_init;
 721         rc = sclp_register(&sclp_vt220_register_input);
 722         if (rc)
 723                 goto out_reg;
 724         sclp_vt220_driver = driver;
 725         return 0;
 726
 727 out_reg:
 728         tty_unregister_driver(driver);
 729 out_init:
 730         __sclp_vt220_cleanup();
 731 out_driver:
 732         put_tty_driver(driver);
 733         return rc;
 734 }
 735 __initcall(sclp_vt220_tty_init);
 736
 737 static void __sclp_vt220_flush_buffer(void)
 738 {
 739         unsigned long flags;
 740
 741         sclp_vt220_emit_current();
 742         spin_lock_irqsave(&sclp_vt220_lock, flags);
 743         if (timer_pending(&sclp_vt220_timer))
 744                 del_timer(&sclp_vt220_timer);
 745         while (sclp_vt220_queue_running) {
 746                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 747                 sclp_sync_wait();
 748                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 749         }
 750         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 751 }
 752
 753 /*
 754  * Resume console: If there are cached messages, emit them.
 755  */
 756 static void sclp_vt220_resume(void)
 757 {
 758         unsigned long flags;
 759
 760         spin_lock_irqsave(&sclp_vt220_lock, flags);
 761         sclp_vt220_suspended = 0;
 762         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 763         sclp_vt220_emit_current();
 764 }
 765
 766 /*
 767  * Suspend console: Set suspend flag and flush console
 768  */
 769 static void sclp_vt220_suspend(void)
 770 {
 771         unsigned long flags;
 772
 773         spin_lock_irqsave(&sclp_vt220_lock, flags);
 774         sclp_vt220_suspended = 1;
 775         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 776         __sclp_vt220_flush_buffer();
 777 }
 778
 779 static void sclp_vt220_pm_event_fn(struct sclp_register *reg,
 780                                    enum sclp_pm_event sclp_pm_event)
 781 {
 782         switch (sclp_pm_event) {
 783         case SCLP_PM_EVENT_FREEZE:
 784                 sclp_vt220_suspend();
 785                 break;
 786         case SCLP_PM_EVENT_RESTORE:
 787         case SCLP_PM_EVENT_THAW:
 788                 sclp_vt220_resume();
 789                 break;
 790         }
 791 }
 792
 793 #ifdef CONFIG_SCLP_VT220_CONSOLE
 794
 795 static void
 796 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 797 {
 798         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1, 0);
 799 }
 800
 801 static struct tty_driver *
 802 sclp_vt220_con_device(struct console *c, int *index)
 803 {
 804         *index = 0;
 805         return sclp_vt220_driver;
 806 }
 807
 808 static int
 809 sclp_vt220_notify(struct notifier_block *self,
 810                           unsigned long event, void *data)
 811 {
 812         __sclp_vt220_flush_buffer();
 813         return NOTIFY_OK;
 814 }
 815
 816 static struct notifier_block on_panic_nb = {
 817         .notifier_call = sclp_vt220_notify,
 818         .priority = 1,
 819 };
 820
 821 static struct notifier_block on_reboot_nb = {
 822         .notifier_call = sclp_vt220_notify,
 823         .priority = 1,
 824 };
 825
 826 /* Structure needed to register with printk */
 827 static struct console sclp_vt220_console =
 828 {
 829         .name = SCLP_VT220_CONSOLE_NAME,
 830         .write = sclp_vt220_con_write,
 831         .device = sclp_vt220_con_device,
 832         .flags = CON_PRINTBUFFER,
 833         .index = SCLP_VT220_CONSOLE_INDEX
 834 };
 835
 836 static int __init
 837 sclp_vt220_con_init(void)
 838 {
 839         int rc;
 840
 841         if (!CONSOLE_IS_SCLP)
 842                 return 0;
 843         rc = __sclp_vt220_init(sclp_console_pages);
 844         if (rc)
 845                 return rc;
 846         /* Attach linux console */
 847         atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
 848         register_reboot_notifier(&on_reboot_nb);
 849         register_console(&sclp_vt220_console);
 850         return 0;
 851 }
 852
 853 console_initcall(sclp_vt220_con_init);
 854 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 855