drivers/s390/char/sclp_vt220.c

   1 /*
   2  *  drivers/s390/char/sclp_vt220.c
   3  *    SCLP VT220 terminal driver.
   4  *
   5  *  S390 version
   6  *    Copyright IBM Corp. 2003,2008
   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/list.h>
  13 #include <linux/wait.h>
  14 #include <linux/timer.h>
  15 #include <linux/kernel.h>
  16 #include <linux/tty.h>
  17 #include <linux/tty_driver.h>
  18 #include <linux/tty_flip.h>
  19 #include <linux/errno.h>
  20 #include <linux/mm.h>
  21 #include <linux/major.h>
  22 #include <linux/console.h>
  23 #include <linux/kdev_t.h>
  24 #include <linux/bootmem.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/init.h>
  27 #include <asm/uaccess.h>
  28 #include "sclp.h"
  29
  30 #define SCLP_VT220_PRINT_HEADER         "sclp vt220 tty driver: "
  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 #define SCLP_VT220_BUF_SIZE             80
  38
  39 /* Representation of a single write request */
  40 struct sclp_vt220_request {
  41         struct list_head list;
  42         struct sclp_req sclp_req;
  43         int retry_count;
  44 };
  45
  46 /* VT220 SCCB */
  47 struct sclp_vt220_sccb {
  48         struct sccb_header header;
  49         struct evbuf_header evbuf;
  50 };
  51
  52 #define SCLP_VT220_MAX_CHARS_PER_BUFFER (PAGE_SIZE - \
  53                                          sizeof(struct sclp_vt220_request) - \
  54                                          sizeof(struct sclp_vt220_sccb))
  55
  56 /* Structures and data needed to register tty driver */
  57 static struct tty_driver *sclp_vt220_driver;
  58
  59 /* The tty_struct that the kernel associated with us */
  60 static struct tty_struct *sclp_vt220_tty;
  61
  62 /* Lock to protect internal data from concurrent access */
  63 static spinlock_t sclp_vt220_lock;
  64
  65 /* List of empty pages to be used as write request buffers */
  66 static struct list_head sclp_vt220_empty;
  67
  68 /* List of pending requests */
  69 static struct list_head sclp_vt220_outqueue;
  70
  71 /* Number of requests in outqueue */
  72 static int sclp_vt220_outqueue_count;
  73
  74 /* Timer used for delaying write requests to merge subsequent messages into
  75  * a single buffer */
  76 static struct timer_list sclp_vt220_timer;
  77
  78 /* Pointer to current request buffer which has been partially filled but not
  79  * yet sent */
  80 static struct sclp_vt220_request *sclp_vt220_current_request;
  81
  82 /* Number of characters in current request buffer */
  83 static int sclp_vt220_buffered_chars;
  84
  85 /* Flag indicating whether this driver has already been initialized */
  86 static int sclp_vt220_initialized = 0;
  87
  88 /* Flag indicating that sclp_vt220_current_request should really
  89  * have been already queued but wasn't because the SCLP was processing
  90  * another buffer */
  91 static int sclp_vt220_flush_later;
  92
  93 static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
  94 static int __sclp_vt220_emit(struct sclp_vt220_request *request);
  95 static void sclp_vt220_emit_current(void);
  96
  97 /* Registration structure for our interest in SCLP event buffers */
  98 static struct sclp_register sclp_vt220_register = {
  99         .send_mask              = EVTYP_VT220MSG_MASK,
 100         .receive_mask           = EVTYP_VT220MSG_MASK,
 101         .state_change_fn        = NULL,
 102         .receiver_fn            = sclp_vt220_receiver_fn
 103 };
 104
 105
 106 /*
 107  * Put provided request buffer back into queue and check emit pending
 108  * buffers if necessary.
 109  */
 110 static void
 111 sclp_vt220_process_queue(struct sclp_vt220_request *request)
 112 {
 113         unsigned long flags;
 114         void *page;
 115
 116         do {
 117                 /* Put buffer back to list of empty buffers */
 118                 page = request->sclp_req.sccb;
 119                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 120                 /* Move request from outqueue to empty queue */
 121                 list_del(&request->list);
 122                 sclp_vt220_outqueue_count--;
 123                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 124                 /* Check if there is a pending buffer on the out queue. */
 125                 request = NULL;
 126                 if (!list_empty(&sclp_vt220_outqueue))
 127                         request = list_entry(sclp_vt220_outqueue.next,
 128                                              struct sclp_vt220_request, list);
 129                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 130         } while (request && __sclp_vt220_emit(request));
 131         if (request == NULL && sclp_vt220_flush_later)
 132                 sclp_vt220_emit_current();
 133         /* Check if the tty needs a wake up call */
 134         if (sclp_vt220_tty != NULL) {
 135                 tty_wakeup(sclp_vt220_tty);
 136         }
 137 }
 138
 139 #define SCLP_BUFFER_MAX_RETRY           1
 140
 141 /*
 142  * Callback through which the result of a write request is reported by the
 143  * SCLP.
 144  */
 145 static void
 146 sclp_vt220_callback(struct sclp_req *request, void *data)
 147 {
 148         struct sclp_vt220_request *vt220_request;
 149         struct sclp_vt220_sccb *sccb;
 150
 151         vt220_request = (struct sclp_vt220_request *) data;
 152         if (request->status == SCLP_REQ_FAILED) {
 153                 sclp_vt220_process_queue(vt220_request);
 154                 return;
 155         }
 156         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
 157
 158         /* Check SCLP response code and choose suitable action  */
 159         switch (sccb->header.response_code) {
 160         case 0x0020 :
 161                 break;
 162
 163         case 0x05f0: /* Target resource in improper state */
 164                 break;
 165
 166         case 0x0340: /* Contained SCLP equipment check */
 167                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 168                         break;
 169                 /* Remove processed buffers and requeue rest */
 170                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 171                         /* Not all buffers were processed */
 172                         sccb->header.response_code = 0x0000;
 173                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 174                         if (sclp_add_request(request) == 0)
 175                                 return;
 176                 }
 177                 break;
 178
 179         case 0x0040: /* SCLP equipment check */
 180                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 181                         break;
 182                 sccb->header.response_code = 0x0000;
 183                 vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 184                 if (sclp_add_request(request) == 0)
 185                         return;
 186                 break;
 187
 188         default:
 189                 break;
 190         }
 191         sclp_vt220_process_queue(vt220_request);
 192 }
 193
 194 /*
 195  * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
 196  * otherwise.
 197  */
 198 static int
 199 __sclp_vt220_emit(struct sclp_vt220_request *request)
 200 {
 201         if (!(sclp_vt220_register.sclp_receive_mask & EVTYP_VT220MSG_MASK)) {
 202                 request->sclp_req.status = SCLP_REQ_FAILED;
 203                 return -EIO;
 204         }
 205         request->sclp_req.command = SCLP_CMDW_WRITE_EVENT_DATA;
 206         request->sclp_req.status = SCLP_REQ_FILLED;
 207         request->sclp_req.callback = sclp_vt220_callback;
 208         request->sclp_req.callback_data = (void *) request;
 209
 210         return sclp_add_request(&request->sclp_req);
 211 }
 212
 213 /*
 214  * Queue and emit given request.
 215  */
 216 static void
 217 sclp_vt220_emit(struct sclp_vt220_request *request)
 218 {
 219         unsigned long flags;
 220         int count;
 221
 222         spin_lock_irqsave(&sclp_vt220_lock, flags);
 223         list_add_tail(&request->list, &sclp_vt220_outqueue);
 224         count = sclp_vt220_outqueue_count++;
 225         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 226         /* Emit only the first buffer immediately - callback takes care of
 227          * the rest */
 228         if (count == 0 && __sclp_vt220_emit(request))
 229                 sclp_vt220_process_queue(request);
 230 }
 231
 232 /*
 233  * Queue and emit current request. Return zero on success, non-zero otherwise.
 234  */
 235 static void
 236 sclp_vt220_emit_current(void)
 237 {
 238         unsigned long flags;
 239         struct sclp_vt220_request *request;
 240         struct sclp_vt220_sccb *sccb;
 241
 242         spin_lock_irqsave(&sclp_vt220_lock, flags);
 243         request = NULL;
 244         if (sclp_vt220_current_request != NULL) {
 245                 sccb = (struct sclp_vt220_sccb *)
 246                                 sclp_vt220_current_request->sclp_req.sccb;
 247                 /* Only emit buffers with content */
 248                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 249                         request = sclp_vt220_current_request;
 250                         sclp_vt220_current_request = NULL;
 251                         if (timer_pending(&sclp_vt220_timer))
 252                                 del_timer(&sclp_vt220_timer);
 253                 }
 254                 sclp_vt220_flush_later = 0;
 255         }
 256         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 257         if (request != NULL)
 258                 sclp_vt220_emit(request);
 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  * Internal implementation of the write function. Write COUNT bytes of data
 370  * from memory at BUF
 371  * to the SCLP interface. In case that the data does not fit into the current
 372  * write buffer, emit the current one and allocate a new one. If there are no
 373  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 374  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 375  * otherwise the user has to explicitly call the flush function.
 376  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 377  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 378  * of bytes written.
 379  */
 380 static int
 381 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 382                    int convertlf, int may_fail)
 383 {
 384         unsigned long flags;
 385         void *page;
 386         int written;
 387         int overall_written;
 388
 389         if (count <= 0)
 390                 return 0;
 391         overall_written = 0;
 392         spin_lock_irqsave(&sclp_vt220_lock, flags);
 393         do {
 394                 /* Create an sclp output buffer if none exists yet */
 395                 if (sclp_vt220_current_request == NULL) {
 396                         while (list_empty(&sclp_vt220_empty)) {
 397                                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 398                                 if (may_fail)
 399                                         goto out;
 400                                 else
 401                                         sclp_sync_wait();
 402                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 403                         }
 404                         page = (void *) sclp_vt220_empty.next;
 405                         list_del((struct list_head *) page);
 406                         sclp_vt220_current_request =
 407                                 sclp_vt220_initialize_page(page);
 408                 }
 409                 /* Try to write the string to the current request buffer */
 410                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 411                                              buf, count, convertlf);
 412                 overall_written += written;
 413                 if (written == count)
 414                         break;
 415                 /*
 416                  * Not all characters could be written to the current
 417                  * output buffer. Emit the buffer, create a new buffer
 418                  * and then output the rest of the string.
 419                  */
 420                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 421                 sclp_vt220_emit_current();
 422                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 423                 buf += written;
 424                 count -= written;
 425         } while (count > 0);
 426         /* Setup timer to output current console buffer after some time */
 427         if (sclp_vt220_current_request != NULL &&
 428             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 429                 sclp_vt220_timer.function = sclp_vt220_timeout;
 430                 sclp_vt220_timer.data = 0UL;
 431                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 432                 add_timer(&sclp_vt220_timer);
 433         }
 434         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 435 out:
 436         return overall_written;
 437 }
 438
 439 /*
 440  * This routine is called by the kernel to write a series of
 441  * characters to the tty device.  The characters may come from
 442  * user space or kernel space.  This routine will return the
 443  * number of characters actually accepted for writing.
 444  */
 445 static int
 446 sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
 447 {
 448         return __sclp_vt220_write(buf, count, 1, 0, 1);
 449 }
 450
 451 #define SCLP_VT220_SESSION_ENDED        0x01
 452 #define SCLP_VT220_SESSION_STARTED      0x80
 453 #define SCLP_VT220_SESSION_DATA         0x00
 454
 455 /*
 456  * Called by the SCLP to report incoming event buffers.
 457  */
 458 static void
 459 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 460 {
 461         char *buffer;
 462         unsigned int count;
 463
 464         /* Ignore input if device is not open */
 465         if (sclp_vt220_tty == NULL)
 466                 return;
 467
 468         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 469         count = evbuf->length - sizeof(struct evbuf_header);
 470
 471         switch (*buffer) {
 472         case SCLP_VT220_SESSION_ENDED:
 473         case SCLP_VT220_SESSION_STARTED:
 474                 break;
 475         case SCLP_VT220_SESSION_DATA:
 476                 /* Send input to line discipline */
 477                 buffer++;
 478                 count--;
 479                 tty_insert_flip_string(sclp_vt220_tty, buffer, count);
 480                 tty_flip_buffer_push(sclp_vt220_tty);
 481                 break;
 482         }
 483 }
 484
 485 /*
 486  * This routine is called when a particular tty device is opened.
 487  */
 488 static int
 489 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 490 {
 491         if (tty->count == 1) {
 492                 sclp_vt220_tty = tty;
 493                 tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
 494                 if (tty->driver_data == NULL)
 495                         return -ENOMEM;
 496                 tty->low_latency = 0;
 497         }
 498         return 0;
 499 }
 500
 501 /*
 502  * This routine is called when a particular tty device is closed.
 503  */
 504 static void
 505 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 506 {
 507         if (tty->count == 1) {
 508                 sclp_vt220_tty = NULL;
 509                 kfree(tty->driver_data);
 510                 tty->driver_data = NULL;
 511         }
 512 }
 513
 514 /*
 515  * This routine is called by the kernel to write a single
 516  * character to the tty device.  If the kernel uses this routine,
 517  * it must call the flush_chars() routine (if defined) when it is
 518  * done stuffing characters into the driver.
 519  */
 520 static int
 521 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 522 {
 523         return __sclp_vt220_write(&ch, 1, 0, 0, 1);
 524 }
 525
 526 /*
 527  * This routine is called by the kernel after it has written a
 528  * series of characters to the tty device using put_char().
 529  */
 530 static void
 531 sclp_vt220_flush_chars(struct tty_struct *tty)
 532 {
 533         if (sclp_vt220_outqueue_count == 0)
 534                 sclp_vt220_emit_current();
 535         else
 536                 sclp_vt220_flush_later = 1;
 537 }
 538
 539 /*
 540  * This routine returns the numbers of characters the tty driver
 541  * will accept for queuing to be written.  This number is subject
 542  * to change as output buffers get emptied, or if the output flow
 543  * control is acted.
 544  */
 545 static int
 546 sclp_vt220_write_room(struct tty_struct *tty)
 547 {
 548         unsigned long flags;
 549         struct list_head *l;
 550         int count;
 551
 552         spin_lock_irqsave(&sclp_vt220_lock, flags);
 553         count = 0;
 554         if (sclp_vt220_current_request != NULL)
 555                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 556         list_for_each(l, &sclp_vt220_empty)
 557                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 558         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 559         return count;
 560 }
 561
 562 /*
 563  * Return number of buffered chars.
 564  */
 565 static int
 566 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 567 {
 568         unsigned long flags;
 569         struct list_head *l;
 570         struct sclp_vt220_request *r;
 571         int count;
 572
 573         spin_lock_irqsave(&sclp_vt220_lock, flags);
 574         count = 0;
 575         if (sclp_vt220_current_request != NULL)
 576                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 577         list_for_each(l, &sclp_vt220_outqueue) {
 578                 r = list_entry(l, struct sclp_vt220_request, list);
 579                 count += sclp_vt220_chars_stored(r);
 580         }
 581         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 582         return count;
 583 }
 584
 585 static void
 586 __sclp_vt220_flush_buffer(void)
 587 {
 588         unsigned long flags;
 589
 590         sclp_vt220_emit_current();
 591         spin_lock_irqsave(&sclp_vt220_lock, flags);
 592         if (timer_pending(&sclp_vt220_timer))
 593                 del_timer(&sclp_vt220_timer);
 594         while (sclp_vt220_outqueue_count > 0) {
 595                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 596                 sclp_sync_wait();
 597                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 598         }
 599         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 600 }
 601
 602 /*
 603  * Pass on all buffers to the hardware. Return only when there are no more
 604  * buffers pending.
 605  */
 606 static void
 607 sclp_vt220_flush_buffer(struct tty_struct *tty)
 608 {
 609         sclp_vt220_emit_current();
 610 }
 611
 612 /*
 613  * Initialize all relevant components and register driver with system.
 614  */
 615 static void __init __sclp_vt220_cleanup(void)
 616 {
 617         struct list_head *page, *p;
 618
 619         list_for_each_safe(page, p, &sclp_vt220_empty) {
 620                 list_del(page);
 621                 if (slab_is_available())
 622                         free_page((unsigned long) page);
 623                 else
 624                         free_bootmem((unsigned long) page, PAGE_SIZE);
 625         }
 626         if (!list_empty(&sclp_vt220_register.list))
 627                 sclp_unregister(&sclp_vt220_register);
 628         sclp_vt220_initialized = 0;
 629 }
 630
 631 static int __init __sclp_vt220_init(void)
 632 {
 633         void *page;
 634         int i;
 635         int num_pages;
 636         int rc;
 637
 638         if (sclp_vt220_initialized)
 639                 return 0;
 640         sclp_vt220_initialized = 1;
 641         spin_lock_init(&sclp_vt220_lock);
 642         INIT_LIST_HEAD(&sclp_vt220_empty);
 643         INIT_LIST_HEAD(&sclp_vt220_outqueue);
 644         init_timer(&sclp_vt220_timer);
 645         sclp_vt220_current_request = NULL;
 646         sclp_vt220_buffered_chars = 0;
 647         sclp_vt220_outqueue_count = 0;
 648         sclp_vt220_tty = NULL;
 649         sclp_vt220_flush_later = 0;
 650
 651         /* Allocate pages for output buffering */
 652         num_pages = slab_is_available() ? MAX_KMEM_PAGES : MAX_CONSOLE_PAGES;
 653         for (i = 0; i < num_pages; i++) {
 654                 if (slab_is_available())
 655                         page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 656                 else
 657                         page = alloc_bootmem_low_pages(PAGE_SIZE);
 658                 if (!page) {
 659                         __sclp_vt220_cleanup();
 660                         return -ENOMEM;
 661                 }
 662                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 663         }
 664         rc = sclp_register(&sclp_vt220_register);
 665         if (rc) {
 666                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 667                        "could not register vt220 - "
 668                        "sclp_register returned %d\n", rc);
 669                 __sclp_vt220_cleanup();
 670         }
 671         return rc;
 672 }
 673
 674 static const struct tty_operations sclp_vt220_ops = {
 675         .open = sclp_vt220_open,
 676         .close = sclp_vt220_close,
 677         .write = sclp_vt220_write,
 678         .put_char = sclp_vt220_put_char,
 679         .flush_chars = sclp_vt220_flush_chars,
 680         .write_room = sclp_vt220_write_room,
 681         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 682         .flush_buffer = sclp_vt220_flush_buffer,
 683 };
 684
 685 /*
 686  * Register driver with SCLP and Linux and initialize internal tty structures.
 687  */
 688 static int __init sclp_vt220_tty_init(void)
 689 {
 690         struct tty_driver *driver;
 691         int rc;
 692         int cleanup;
 693
 694         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 695          * symmetry between VM and LPAR systems regarding ttyS1. */
 696         driver = alloc_tty_driver(1);
 697         if (!driver)
 698                 return -ENOMEM;
 699         cleanup = !sclp_vt220_initialized;
 700         rc = __sclp_vt220_init();
 701         if (rc)
 702                 goto out_driver;
 703
 704         driver->owner = THIS_MODULE;
 705         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 706         driver->name = SCLP_VT220_DEVICE_NAME;
 707         driver->major = SCLP_VT220_MAJOR;
 708         driver->minor_start = SCLP_VT220_MINOR;
 709         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 710         driver->subtype = SYSTEM_TYPE_TTY;
 711         driver->init_termios = tty_std_termios;
 712         driver->flags = TTY_DRIVER_REAL_RAW;
 713         tty_set_operations(driver, &sclp_vt220_ops);
 714
 715         rc = tty_register_driver(driver);
 716         if (rc) {
 717                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 718                        "could not register tty - "
 719                        "tty_register_driver returned %d\n", rc);
 720                 goto out_init;
 721         }
 722         sclp_vt220_driver = driver;
 723         return 0;
 724
 725 out_init:
 726         if (cleanup)
 727                 __sclp_vt220_cleanup();
 728 out_driver:
 729         put_tty_driver(driver);
 730         return rc;
 731 }
 732 __initcall(sclp_vt220_tty_init);
 733
 734 #ifdef CONFIG_SCLP_VT220_CONSOLE
 735
 736 static void
 737 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 738 {
 739         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1, 0);
 740 }
 741
 742 static struct tty_driver *
 743 sclp_vt220_con_device(struct console *c, int *index)
 744 {
 745         *index = 0;
 746         return sclp_vt220_driver;
 747 }
 748
 749 /*
 750  * This routine is called from panic when the kernel is going to give up.
 751  * We have to make sure that all buffers will be flushed to the SCLP.
 752  * Note that this function may be called from within an interrupt context.
 753  */
 754 static void
 755 sclp_vt220_con_unblank(void)
 756 {
 757         __sclp_vt220_flush_buffer();
 758 }
 759
 760 /* Structure needed to register with printk */
 761 static struct console sclp_vt220_console =
 762 {
 763         .name = SCLP_VT220_CONSOLE_NAME,
 764         .write = sclp_vt220_con_write,
 765         .device = sclp_vt220_con_device,
 766         .unblank = sclp_vt220_con_unblank,
 767         .flags = CON_PRINTBUFFER,
 768         .index = SCLP_VT220_CONSOLE_INDEX
 769 };
 770
 771 static int __init
 772 sclp_vt220_con_init(void)
 773 {
 774         int rc;
 775
 776         if (!CONSOLE_IS_SCLP)
 777                 return 0;
 778         rc = __sclp_vt220_init();
 779         if (rc)
 780                 return rc;
 781         /* Attach linux console */
 782         register_console(&sclp_vt220_console);
 783         return 0;
 784 }
 785
 786 console_initcall(sclp_vt220_con_init);
 787 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 788