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_MAJOR                TTY_MAJOR
  31 #define SCLP_VT220_MINOR                65
  32 #define SCLP_VT220_DRIVER_NAME          "sclp_vt220"
  33 #define SCLP_VT220_DEVICE_NAME          "ttysclp"
  34 #define SCLP_VT220_CONSOLE_NAME         "ttyS"
  35 #define SCLP_VT220_CONSOLE_INDEX        1       /* console=ttyS1 */
  36 #define SCLP_VT220_BUF_SIZE             80
  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 /* The tty_struct that the kernel associated with us */
  59 static struct tty_struct *sclp_vt220_tty;
  60
  61 /* Lock to protect internal data from concurrent access */
  62 static spinlock_t sclp_vt220_lock;
  63
  64 /* List of empty pages to be used as write request buffers */
  65 static struct list_head sclp_vt220_empty;
  66
  67 /* List of pending requests */
  68 static struct list_head sclp_vt220_outqueue;
  69
  70 /* Number of requests in outqueue */
  71 static int sclp_vt220_outqueue_count;
  72
  73 /* Timer used for delaying write requests to merge subsequent messages into
  74  * a single buffer */
  75 static struct timer_list sclp_vt220_timer;
  76
  77 /* Pointer to current request buffer which has been partially filled but not
  78  * yet sent */
  79 static struct sclp_vt220_request *sclp_vt220_current_request;
  80
  81 /* Number of characters in current request buffer */
  82 static int sclp_vt220_buffered_chars;
  83
  84 /* Counter controlling core driver initialization. */
  85 static int __initdata sclp_vt220_init_count;
  86
  87 /* Flag indicating that sclp_vt220_current_request should really
  88  * have been already queued but wasn't because the SCLP was processing
  89  * another buffer */
  90 static int sclp_vt220_flush_later;
  91
  92 static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
  93 static int __sclp_vt220_emit(struct sclp_vt220_request *request);
  94 static void sclp_vt220_emit_current(void);
  95
  96 /* Registration structure for our interest in SCLP event buffers */
  97 static struct sclp_register sclp_vt220_register = {
  98         .send_mask              = EVTYP_VT220MSG_MASK,
  99         .receive_mask           = EVTYP_VT220MSG_MASK,
 100         .state_change_fn        = NULL,
 101         .receiver_fn            = sclp_vt220_receiver_fn
 102 };
 103
 104
 105 /*
 106  * Put provided request buffer back into queue and check emit pending
 107  * buffers if necessary.
 108  */
 109 static void
 110 sclp_vt220_process_queue(struct sclp_vt220_request *request)
 111 {
 112         unsigned long flags;
 113         void *page;
 114
 115         do {
 116                 /* Put buffer back to list of empty buffers */
 117                 page = request->sclp_req.sccb;
 118                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 119                 /* Move request from outqueue to empty queue */
 120                 list_del(&request->list);
 121                 sclp_vt220_outqueue_count--;
 122                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 123                 /* Check if there is a pending buffer on the out queue. */
 124                 request = NULL;
 125                 if (!list_empty(&sclp_vt220_outqueue))
 126                         request = list_entry(sclp_vt220_outqueue.next,
 127                                              struct sclp_vt220_request, list);
 128                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 129         } while (request && __sclp_vt220_emit(request));
 130         if (request == NULL && sclp_vt220_flush_later)
 131                 sclp_vt220_emit_current();
 132         /* Check if the tty needs a wake up call */
 133         if (sclp_vt220_tty != NULL) {
 134                 tty_wakeup(sclp_vt220_tty);
 135         }
 136 }
 137
 138 #define SCLP_BUFFER_MAX_RETRY           1
 139
 140 /*
 141  * Callback through which the result of a write request is reported by the
 142  * SCLP.
 143  */
 144 static void
 145 sclp_vt220_callback(struct sclp_req *request, void *data)
 146 {
 147         struct sclp_vt220_request *vt220_request;
 148         struct sclp_vt220_sccb *sccb;
 149
 150         vt220_request = (struct sclp_vt220_request *) data;
 151         if (request->status == SCLP_REQ_FAILED) {
 152                 sclp_vt220_process_queue(vt220_request);
 153                 return;
 154         }
 155         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
 156
 157         /* Check SCLP response code and choose suitable action  */
 158         switch (sccb->header.response_code) {
 159         case 0x0020 :
 160                 break;
 161
 162         case 0x05f0: /* Target resource in improper state */
 163                 break;
 164
 165         case 0x0340: /* Contained SCLP equipment check */
 166                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 167                         break;
 168                 /* Remove processed buffers and requeue rest */
 169                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 170                         /* Not all buffers were processed */
 171                         sccb->header.response_code = 0x0000;
 172                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 173                         if (sclp_add_request(request) == 0)
 174                                 return;
 175                 }
 176                 break;
 177
 178         case 0x0040: /* SCLP equipment check */
 179                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 180                         break;
 181                 sccb->header.response_code = 0x0000;
 182                 vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 183                 if (sclp_add_request(request) == 0)
 184                         return;
 185                 break;
 186
 187         default:
 188                 break;
 189         }
 190         sclp_vt220_process_queue(vt220_request);
 191 }
 192
 193 /*
 194  * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
 195  * otherwise.
 196  */
 197 static int
 198 __sclp_vt220_emit(struct sclp_vt220_request *request)
 199 {
 200         if (!(sclp_vt220_register.sclp_receive_mask & EVTYP_VT220MSG_MASK)) {
 201                 request->sclp_req.status = SCLP_REQ_FAILED;
 202                 return -EIO;
 203         }
 204         request->sclp_req.command = SCLP_CMDW_WRITE_EVENT_DATA;
 205         request->sclp_req.status = SCLP_REQ_FILLED;
 206         request->sclp_req.callback = sclp_vt220_callback;
 207         request->sclp_req.callback_data = (void *) request;
 208
 209         return sclp_add_request(&request->sclp_req);
 210 }
 211
 212 /*
 213  * Queue and emit given request.
 214  */
 215 static void
 216 sclp_vt220_emit(struct sclp_vt220_request *request)
 217 {
 218         unsigned long flags;
 219         int count;
 220
 221         spin_lock_irqsave(&sclp_vt220_lock, flags);
 222         list_add_tail(&request->list, &sclp_vt220_outqueue);
 223         count = sclp_vt220_outqueue_count++;
 224         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 225         /* Emit only the first buffer immediately - callback takes care of
 226          * the rest */
 227         if (count == 0 && __sclp_vt220_emit(request))
 228                 sclp_vt220_process_queue(request);
 229 }
 230
 231 /*
 232  * Queue and emit current request. Return zero on success, non-zero otherwise.
 233  */
 234 static void
 235 sclp_vt220_emit_current(void)
 236 {
 237         unsigned long flags;
 238         struct sclp_vt220_request *request;
 239         struct sclp_vt220_sccb *sccb;
 240
 241         spin_lock_irqsave(&sclp_vt220_lock, flags);
 242         request = NULL;
 243         if (sclp_vt220_current_request != NULL) {
 244                 sccb = (struct sclp_vt220_sccb *)
 245                                 sclp_vt220_current_request->sclp_req.sccb;
 246                 /* Only emit buffers with content */
 247                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 248                         request = sclp_vt220_current_request;
 249                         sclp_vt220_current_request = NULL;
 250                         if (timer_pending(&sclp_vt220_timer))
 251                                 del_timer(&sclp_vt220_timer);
 252                 }
 253                 sclp_vt220_flush_later = 0;
 254         }
 255         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 256         if (request != NULL)
 257                 sclp_vt220_emit(request);
 258 }
 259
 260 #define SCLP_NORMAL_WRITE       0x00
 261
 262 /*
 263  * Helper function to initialize a page with the sclp request structure.
 264  */
 265 static struct sclp_vt220_request *
 266 sclp_vt220_initialize_page(void *page)
 267 {
 268         struct sclp_vt220_request *request;
 269         struct sclp_vt220_sccb *sccb;
 270
 271         /* Place request structure at end of page */
 272         request = ((struct sclp_vt220_request *)
 273                         ((addr_t) page + PAGE_SIZE)) - 1;
 274         request->retry_count = 0;
 275         request->sclp_req.sccb = page;
 276         /* SCCB goes at start of page */
 277         sccb = (struct sclp_vt220_sccb *) page;
 278         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
 279         sccb->header.length = sizeof(struct sclp_vt220_sccb);
 280         sccb->header.function_code = SCLP_NORMAL_WRITE;
 281         sccb->header.response_code = 0x0000;
 282         sccb->evbuf.type = EVTYP_VT220MSG;
 283         sccb->evbuf.length = sizeof(struct evbuf_header);
 284
 285         return request;
 286 }
 287
 288 static inline unsigned int
 289 sclp_vt220_space_left(struct sclp_vt220_request *request)
 290 {
 291         struct sclp_vt220_sccb *sccb;
 292         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 293         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
 294                sccb->header.length;
 295 }
 296
 297 static inline unsigned int
 298 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
 299 {
 300         struct sclp_vt220_sccb *sccb;
 301         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 302         return sccb->evbuf.length - sizeof(struct evbuf_header);
 303 }
 304
 305 /*
 306  * Add msg to buffer associated with request. Return the number of characters
 307  * added.
 308  */
 309 static int
 310 sclp_vt220_add_msg(struct sclp_vt220_request *request,
 311                    const unsigned char *msg, int count, int convertlf)
 312 {
 313         struct sclp_vt220_sccb *sccb;
 314         void *buffer;
 315         unsigned char c;
 316         int from;
 317         int to;
 318
 319         if (count > sclp_vt220_space_left(request))
 320                 count = sclp_vt220_space_left(request);
 321         if (count <= 0)
 322                 return 0;
 323
 324         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 325         buffer = (void *) ((addr_t) sccb + sccb->header.length);
 326
 327         if (convertlf) {
 328                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
 329                 for (from=0, to=0;
 330                      (from < count) && (to < sclp_vt220_space_left(request));
 331                      from++) {
 332                         /* Retrieve character */
 333                         c = msg[from];
 334                         /* Perform conversion */
 335                         if (c == 0x0a) {
 336                                 if (to + 1 < sclp_vt220_space_left(request)) {
 337                                         ((unsigned char *) buffer)[to++] = c;
 338                                         ((unsigned char *) buffer)[to++] = 0x0d;
 339                                 } else
 340                                         break;
 341
 342                         } else
 343                                 ((unsigned char *) buffer)[to++] = c;
 344                 }
 345                 sccb->header.length += to;
 346                 sccb->evbuf.length += to;
 347                 return from;
 348         } else {
 349                 memcpy(buffer, (const void *) msg, count);
 350                 sccb->header.length += count;
 351                 sccb->evbuf.length += count;
 352                 return count;
 353         }
 354 }
 355
 356 /*
 357  * Emit buffer after having waited long enough for more data to arrive.
 358  */
 359 static void
 360 sclp_vt220_timeout(unsigned long data)
 361 {
 362         sclp_vt220_emit_current();
 363 }
 364
 365 #define BUFFER_MAX_DELAY        HZ/20
 366
 367 /*
 368  * Internal implementation of the write function. Write COUNT bytes of data
 369  * from memory at BUF
 370  * to the SCLP interface. In case that the data does not fit into the current
 371  * write buffer, emit the current one and allocate a new one. If there are no
 372  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 373  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 374  * otherwise the user has to explicitly call the flush function.
 375  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 376  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 377  * of bytes written.
 378  */
 379 static int
 380 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 381                    int convertlf, int may_fail)
 382 {
 383         unsigned long flags;
 384         void *page;
 385         int written;
 386         int overall_written;
 387
 388         if (count <= 0)
 389                 return 0;
 390         overall_written = 0;
 391         spin_lock_irqsave(&sclp_vt220_lock, flags);
 392         do {
 393                 /* Create an sclp output buffer if none exists yet */
 394                 if (sclp_vt220_current_request == NULL) {
 395                         while (list_empty(&sclp_vt220_empty)) {
 396                                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 397                                 if (may_fail)
 398                                         goto out;
 399                                 else
 400                                         sclp_sync_wait();
 401                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 402                         }
 403                         page = (void *) sclp_vt220_empty.next;
 404                         list_del((struct list_head *) page);
 405                         sclp_vt220_current_request =
 406                                 sclp_vt220_initialize_page(page);
 407                 }
 408                 /* Try to write the string to the current request buffer */
 409                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 410                                              buf, count, convertlf);
 411                 overall_written += written;
 412                 if (written == count)
 413                         break;
 414                 /*
 415                  * Not all characters could be written to the current
 416                  * output buffer. Emit the buffer, create a new buffer
 417                  * and then output the rest of the string.
 418                  */
 419                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 420                 sclp_vt220_emit_current();
 421                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 422                 buf += written;
 423                 count -= written;
 424         } while (count > 0);
 425         /* Setup timer to output current console buffer after some time */
 426         if (sclp_vt220_current_request != NULL &&
 427             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 428                 sclp_vt220_timer.function = sclp_vt220_timeout;
 429                 sclp_vt220_timer.data = 0UL;
 430                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 431                 add_timer(&sclp_vt220_timer);
 432         }
 433         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 434 out:
 435         return overall_written;
 436 }
 437
 438 /*
 439  * This routine is called by the kernel to write a series of
 440  * characters to the tty device.  The characters may come from
 441  * user space or kernel space.  This routine will return the
 442  * number of characters actually accepted for writing.
 443  */
 444 static int
 445 sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
 446 {
 447         return __sclp_vt220_write(buf, count, 1, 0, 1);
 448 }
 449
 450 #define SCLP_VT220_SESSION_ENDED        0x01
 451 #define SCLP_VT220_SESSION_STARTED      0x80
 452 #define SCLP_VT220_SESSION_DATA         0x00
 453
 454 /*
 455  * Called by the SCLP to report incoming event buffers.
 456  */
 457 static void
 458 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 459 {
 460         char *buffer;
 461         unsigned int count;
 462
 463         /* Ignore input if device is not open */
 464         if (sclp_vt220_tty == NULL)
 465                 return;
 466
 467         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 468         count = evbuf->length - sizeof(struct evbuf_header);
 469
 470         switch (*buffer) {
 471         case SCLP_VT220_SESSION_ENDED:
 472         case SCLP_VT220_SESSION_STARTED:
 473                 break;
 474         case SCLP_VT220_SESSION_DATA:
 475                 /* Send input to line discipline */
 476                 buffer++;
 477                 count--;
 478                 tty_insert_flip_string(sclp_vt220_tty, buffer, count);
 479                 tty_flip_buffer_push(sclp_vt220_tty);
 480                 break;
 481         }
 482 }
 483
 484 /*
 485  * This routine is called when a particular tty device is opened.
 486  */
 487 static int
 488 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 489 {
 490         if (tty->count == 1) {
 491                 sclp_vt220_tty = tty;
 492                 tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
 493                 if (tty->driver_data == NULL)
 494                         return -ENOMEM;
 495                 tty->low_latency = 0;
 496         }
 497         return 0;
 498 }
 499
 500 /*
 501  * This routine is called when a particular tty device is closed.
 502  */
 503 static void
 504 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 505 {
 506         if (tty->count == 1) {
 507                 sclp_vt220_tty = NULL;
 508                 kfree(tty->driver_data);
 509                 tty->driver_data = NULL;
 510         }
 511 }
 512
 513 /*
 514  * This routine is called by the kernel to write a single
 515  * character to the tty device.  If the kernel uses this routine,
 516  * it must call the flush_chars() routine (if defined) when it is
 517  * done stuffing characters into the driver.
 518  */
 519 static int
 520 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 521 {
 522         return __sclp_vt220_write(&ch, 1, 0, 0, 1);
 523 }
 524
 525 /*
 526  * This routine is called by the kernel after it has written a
 527  * series of characters to the tty device using put_char().
 528  */
 529 static void
 530 sclp_vt220_flush_chars(struct tty_struct *tty)
 531 {
 532         if (sclp_vt220_outqueue_count == 0)
 533                 sclp_vt220_emit_current();
 534         else
 535                 sclp_vt220_flush_later = 1;
 536 }
 537
 538 /*
 539  * This routine returns the numbers of characters the tty driver
 540  * will accept for queuing to be written.  This number is subject
 541  * to change as output buffers get emptied, or if the output flow
 542  * control is acted.
 543  */
 544 static int
 545 sclp_vt220_write_room(struct tty_struct *tty)
 546 {
 547         unsigned long flags;
 548         struct list_head *l;
 549         int count;
 550
 551         spin_lock_irqsave(&sclp_vt220_lock, flags);
 552         count = 0;
 553         if (sclp_vt220_current_request != NULL)
 554                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 555         list_for_each(l, &sclp_vt220_empty)
 556                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 557         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 558         return count;
 559 }
 560
 561 /*
 562  * Return number of buffered chars.
 563  */
 564 static int
 565 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 566 {
 567         unsigned long flags;
 568         struct list_head *l;
 569         struct sclp_vt220_request *r;
 570         int count;
 571
 572         spin_lock_irqsave(&sclp_vt220_lock, flags);
 573         count = 0;
 574         if (sclp_vt220_current_request != NULL)
 575                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 576         list_for_each(l, &sclp_vt220_outqueue) {
 577                 r = list_entry(l, struct sclp_vt220_request, list);
 578                 count += sclp_vt220_chars_stored(r);
 579         }
 580         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 581         return count;
 582 }
 583
 584 static void
 585 __sclp_vt220_flush_buffer(void)
 586 {
 587         unsigned long flags;
 588
 589         sclp_vt220_emit_current();
 590         spin_lock_irqsave(&sclp_vt220_lock, flags);
 591         if (timer_pending(&sclp_vt220_timer))
 592                 del_timer(&sclp_vt220_timer);
 593         while (sclp_vt220_outqueue_count > 0) {
 594                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 595                 sclp_sync_wait();
 596                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 597         }
 598         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 599 }
 600
 601 /*
 602  * Pass on all buffers to the hardware. Return only when there are no more
 603  * buffers pending.
 604  */
 605 static void
 606 sclp_vt220_flush_buffer(struct tty_struct *tty)
 607 {
 608         sclp_vt220_emit_current();
 609 }
 610
 611 /* Release allocated pages. */
 612 static void __init __sclp_vt220_free_pages(void)
 613 {
 614         struct list_head *page, *p;
 615
 616         list_for_each_safe(page, p, &sclp_vt220_empty) {
 617                 list_del(page);
 618                 if (slab_is_available())
 619                         free_page((unsigned long) page);
 620                 else
 621                         free_bootmem((unsigned long) page, PAGE_SIZE);
 622         }
 623 }
 624
 625 /* Release memory and unregister from sclp core. Controlled by init counting -
 626  * only the last invoker will actually perform these actions. */
 627 static void __init __sclp_vt220_cleanup(void)
 628 {
 629         sclp_vt220_init_count--;
 630         if (sclp_vt220_init_count != 0)
 631                 return;
 632         sclp_unregister(&sclp_vt220_register);
 633         __sclp_vt220_free_pages();
 634 }
 635
 636 /* Allocate buffer pages and register with sclp core. Controlled by init
 637  * counting - only the first invoker will actually perform these actions. */
 638 static int __init __sclp_vt220_init(int num_pages)
 639 {
 640         void *page;
 641         int i;
 642         int rc;
 643
 644         sclp_vt220_init_count++;
 645         if (sclp_vt220_init_count != 1)
 646                 return 0;
 647         spin_lock_init(&sclp_vt220_lock);
 648         INIT_LIST_HEAD(&sclp_vt220_empty);
 649         INIT_LIST_HEAD(&sclp_vt220_outqueue);
 650         init_timer(&sclp_vt220_timer);
 651         sclp_vt220_current_request = NULL;
 652         sclp_vt220_buffered_chars = 0;
 653         sclp_vt220_outqueue_count = 0;
 654         sclp_vt220_tty = NULL;
 655         sclp_vt220_flush_later = 0;
 656
 657         /* Allocate pages for output buffering */
 658         for (i = 0; i < num_pages; i++) {
 659                 if (slab_is_available())
 660                         page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 661                 else
 662                         page = alloc_bootmem_low_pages(PAGE_SIZE);
 663                 if (!page) {
 664                         rc = -ENOMEM;
 665                         goto out;
 666                 }
 667                 list_add_tail((struct list_head *) 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         }
 675         return rc;
 676 }
 677
 678 static const struct tty_operations sclp_vt220_ops = {
 679         .open = sclp_vt220_open,
 680         .close = sclp_vt220_close,
 681         .write = sclp_vt220_write,
 682         .put_char = sclp_vt220_put_char,
 683         .flush_chars = sclp_vt220_flush_chars,
 684         .write_room = sclp_vt220_write_room,
 685         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 686         .flush_buffer = sclp_vt220_flush_buffer,
 687 };
 688
 689 /*
 690  * Register driver with SCLP and Linux and initialize internal tty structures.
 691  */
 692 static int __init sclp_vt220_tty_init(void)
 693 {
 694         struct tty_driver *driver;
 695         int rc;
 696
 697         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 698          * symmetry between VM and LPAR systems regarding ttyS1. */
 699         driver = alloc_tty_driver(1);
 700         if (!driver)
 701                 return -ENOMEM;
 702         rc = __sclp_vt220_init(MAX_KMEM_PAGES);
 703         if (rc)
 704                 goto out_driver;
 705
 706         driver->owner = THIS_MODULE;
 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
 717         rc = tty_register_driver(driver);
 718         if (rc)
 719                 goto out_init;
 720         sclp_vt220_driver = driver;
 721         return 0;
 722
 723 out_init:
 724         __sclp_vt220_cleanup();
 725 out_driver:
 726         put_tty_driver(driver);
 727         return rc;
 728 }
 729 __initcall(sclp_vt220_tty_init);
 730
 731 #ifdef CONFIG_SCLP_VT220_CONSOLE
 732
 733 static void
 734 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 735 {
 736         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1, 0);
 737 }
 738
 739 static struct tty_driver *
 740 sclp_vt220_con_device(struct console *c, int *index)
 741 {
 742         *index = 0;
 743         return sclp_vt220_driver;
 744 }
 745
 746 /*
 747  * This routine is called from panic when the kernel is going to give up.
 748  * We have to make sure that all buffers will be flushed to the SCLP.
 749  * Note that this function may be called from within an interrupt context.
 750  */
 751 static void
 752 sclp_vt220_con_unblank(void)
 753 {
 754         __sclp_vt220_flush_buffer();
 755 }
 756
 757 /* Structure needed to register with printk */
 758 static struct console sclp_vt220_console =
 759 {
 760         .name = SCLP_VT220_CONSOLE_NAME,
 761         .write = sclp_vt220_con_write,
 762         .device = sclp_vt220_con_device,
 763         .unblank = sclp_vt220_con_unblank,
 764         .flags = CON_PRINTBUFFER,
 765         .index = SCLP_VT220_CONSOLE_INDEX
 766 };
 767
 768 static int __init
 769 sclp_vt220_con_init(void)
 770 {
 771         int rc;
 772
 773         if (!CONSOLE_IS_SCLP)
 774                 return 0;
 775         rc = __sclp_vt220_init(MAX_CONSOLE_PAGES);
 776         if (rc)
 777                 return rc;
 778         /* Attach linux console */
 779         register_console(&sclp_vt220_console);
 780         return 0;
 781 }
 782
 783 console_initcall(sclp_vt220_con_init);
 784 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 785