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   1 /*
   2  *  drivers/s390/char/sclp_vt220.c
   3  *    SCLP VT220 terminal driver.
   4  *
   5  *  S390 version
   6  *    Copyright (C) 2003 IBM Deutschland Entwicklung GmbH, IBM Corporation
   7  *    Author(s): Peter Oberparleiter <Peter.Oberparleiter@de.ibm.com>
   8  */
   9
  10 #include <linux/config.h>
  11 #include <linux/module.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/list.h>
  14 #include <linux/wait.h>
  15 #include <linux/timer.h>
  16 #include <linux/kernel.h>
  17 #include <linux/tty.h>
  18 #include <linux/tty_driver.h>
  19 #include <linux/tty_flip.h>
  20 #include <linux/sched.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/bootmem.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/init.h>
  29 #include <asm/uaccess.h>
  30 #include "sclp.h"
  31
  32 #define SCLP_VT220_PRINT_HEADER         "sclp vt220 tty driver: "
  33 #define SCLP_VT220_MAJOR                TTY_MAJOR
  34 #define SCLP_VT220_MINOR                65
  35 #define SCLP_VT220_DRIVER_NAME          "sclp_vt220"
  36 #define SCLP_VT220_DEVICE_NAME          "ttysclp"
  37 #define SCLP_VT220_CONSOLE_NAME         "ttyS"
  38 #define SCLP_VT220_CONSOLE_INDEX        1       /* console=ttyS1 */
  39 #define SCLP_VT220_BUF_SIZE             80
  40
  41 /* Representation of a single write request */
  42 struct sclp_vt220_request {
  43         struct list_head list;
  44         struct sclp_req sclp_req;
  45         int retry_count;
  46 };
  47
  48 /* VT220 SCCB */
  49 struct sclp_vt220_sccb {
  50         struct sccb_header header;
  51         struct evbuf_header evbuf;
  52 };
  53
  54 #define SCLP_VT220_MAX_CHARS_PER_BUFFER (PAGE_SIZE - \
  55                                          sizeof(struct sclp_vt220_request) - \
  56                                          sizeof(struct sclp_vt220_sccb))
  57
  58 /* Structures and data needed to register tty driver */
  59 static struct tty_driver *sclp_vt220_driver;
  60
  61 /* The tty_struct that the kernel associated with us */
  62 static struct tty_struct *sclp_vt220_tty;
  63
  64 /* Lock to protect internal data from concurrent access */
  65 static spinlock_t sclp_vt220_lock;
  66
  67 /* List of empty pages to be used as write request buffers */
  68 static struct list_head sclp_vt220_empty;
  69
  70 /* List of pending requests */
  71 static struct list_head sclp_vt220_outqueue;
  72
  73 /* Number of requests in outqueue */
  74 static int sclp_vt220_outqueue_count;
  75
  76 /* Wait queue used to delay write requests while we've run out of buffers */
  77 static wait_queue_head_t sclp_vt220_waitq;
  78
  79 /* Timer used for delaying write requests to merge subsequent messages into
  80  * a single buffer */
  81 static struct timer_list sclp_vt220_timer;
  82
  83 /* Pointer to current request buffer which has been partially filled but not
  84  * yet sent */
  85 static struct sclp_vt220_request *sclp_vt220_current_request;
  86
  87 /* Number of characters in current request buffer */
  88 static int sclp_vt220_buffered_chars;
  89
  90 /* Flag indicating whether this driver has already been initialized */
  91 static int sclp_vt220_initialized = 0;
  92
  93 /* Flag indicating that sclp_vt220_current_request should really
  94  * have been already queued but wasn't because the SCLP was processing
  95  * another buffer */
  96 static int sclp_vt220_flush_later;
  97
  98 static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
  99 static int __sclp_vt220_emit(struct sclp_vt220_request *request);
 100 static void sclp_vt220_emit_current(void);
 101
 102 /* Registration structure for our interest in SCLP event buffers */
 103 static struct sclp_register sclp_vt220_register = {
 104         .send_mask              = EvTyp_VT220Msg_Mask,
 105         .receive_mask           = EvTyp_VT220Msg_Mask,
 106         .state_change_fn        = NULL,
 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                 sclp_vt220_outqueue_count--;
 128                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 129                 /* Check if there is a pending buffer on the out queue. */
 130                 request = NULL;
 131                 if (!list_empty(&sclp_vt220_outqueue))
 132                         request = list_entry(sclp_vt220_outqueue.next,
 133                                              struct sclp_vt220_request, list);
 134                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 135         } while (request && __sclp_vt220_emit(request));
 136         if (request == NULL && sclp_vt220_flush_later)
 137                 sclp_vt220_emit_current();
 138         wake_up(&sclp_vt220_waitq);
 139         /* Check if the tty needs a wake up call */
 140         if (sclp_vt220_tty != NULL) {
 141                 tty_wakeup(sclp_vt220_tty);
 142         }
 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         if (!(sclp_vt220_register.sclp_send_mask & EvTyp_VT220Msg_Mask)) {
 208                 request->sclp_req.status = SCLP_REQ_FAILED;
 209                 return -EIO;
 210         }
 211         request->sclp_req.command = SCLP_CMDW_WRITEDATA;
 212         request->sclp_req.status = SCLP_REQ_FILLED;
 213         request->sclp_req.callback = sclp_vt220_callback;
 214         request->sclp_req.callback_data = (void *) request;
 215
 216         return sclp_add_request(&request->sclp_req);
 217 }
 218
 219 /*
 220  * Queue and emit given request.
 221  */
 222 static void
 223 sclp_vt220_emit(struct sclp_vt220_request *request)
 224 {
 225         unsigned long flags;
 226         int count;
 227
 228         spin_lock_irqsave(&sclp_vt220_lock, flags);
 229         list_add_tail(&request->list, &sclp_vt220_outqueue);
 230         count = sclp_vt220_outqueue_count++;
 231         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 232         /* Emit only the first buffer immediately - callback takes care of
 233          * the rest */
 234         if (count == 0 && __sclp_vt220_emit(request))
 235                 sclp_vt220_process_queue(request);
 236 }
 237
 238 /*
 239  * Queue and emit current request. Return zero on success, non-zero otherwise.
 240  */
 241 static void
 242 sclp_vt220_emit_current(void)
 243 {
 244         unsigned long flags;
 245         struct sclp_vt220_request *request;
 246         struct sclp_vt220_sccb *sccb;
 247
 248         spin_lock_irqsave(&sclp_vt220_lock, flags);
 249         request = NULL;
 250         if (sclp_vt220_current_request != NULL) {
 251                 sccb = (struct sclp_vt220_sccb *)
 252                                 sclp_vt220_current_request->sclp_req.sccb;
 253                 /* Only emit buffers with content */
 254                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 255                         request = sclp_vt220_current_request;
 256                         sclp_vt220_current_request = NULL;
 257                         if (timer_pending(&sclp_vt220_timer))
 258                                 del_timer(&sclp_vt220_timer);
 259                 }
 260                 sclp_vt220_flush_later = 0;
 261         }
 262         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 263         if (request != NULL)
 264                 sclp_vt220_emit(request);
 265 }
 266
 267 #define SCLP_NORMAL_WRITE       0x00
 268
 269 /*
 270  * Helper function to initialize a page with the sclp request structure.
 271  */
 272 static struct sclp_vt220_request *
 273 sclp_vt220_initialize_page(void *page)
 274 {
 275         struct sclp_vt220_request *request;
 276         struct sclp_vt220_sccb *sccb;
 277
 278         /* Place request structure at end of page */
 279         request = ((struct sclp_vt220_request *)
 280                         ((addr_t) page + PAGE_SIZE)) - 1;
 281         request->retry_count = 0;
 282         request->sclp_req.sccb = page;
 283         /* SCCB goes at start of page */
 284         sccb = (struct sclp_vt220_sccb *) page;
 285         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
 286         sccb->header.length = sizeof(struct sclp_vt220_sccb);
 287         sccb->header.function_code = SCLP_NORMAL_WRITE;
 288         sccb->header.response_code = 0x0000;
 289         sccb->evbuf.type = EvTyp_VT220Msg;
 290         sccb->evbuf.length = sizeof(struct evbuf_header);
 291
 292         return request;
 293 }
 294
 295 static inline unsigned int
 296 sclp_vt220_space_left(struct sclp_vt220_request *request)
 297 {
 298         struct sclp_vt220_sccb *sccb;
 299         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 300         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
 301                sccb->header.length;
 302 }
 303
 304 static inline unsigned int
 305 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
 306 {
 307         struct sclp_vt220_sccb *sccb;
 308         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 309         return sccb->evbuf.length - sizeof(struct evbuf_header);
 310 }
 311
 312 /*
 313  * Add msg to buffer associated with request. Return the number of characters
 314  * added.
 315  */
 316 static int
 317 sclp_vt220_add_msg(struct sclp_vt220_request *request,
 318                    const unsigned char *msg, int count, int convertlf)
 319 {
 320         struct sclp_vt220_sccb *sccb;
 321         void *buffer;
 322         unsigned char c;
 323         int from;
 324         int to;
 325
 326         if (count > sclp_vt220_space_left(request))
 327                 count = sclp_vt220_space_left(request);
 328         if (count <= 0)
 329                 return 0;
 330
 331         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 332         buffer = (void *) ((addr_t) sccb + sccb->header.length);
 333
 334         if (convertlf) {
 335                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
 336                 for (from=0, to=0;
 337                      (from < count) && (to < sclp_vt220_space_left(request));
 338                      from++) {
 339                         /* Retrieve character */
 340                         c = msg[from];
 341                         /* Perform conversion */
 342                         if (c == 0x0a) {
 343                                 if (to + 1 < sclp_vt220_space_left(request)) {
 344                                         ((unsigned char *) buffer)[to++] = c;
 345                                         ((unsigned char *) buffer)[to++] = 0x0d;
 346                                 } else
 347                                         break;
 348
 349                         } else
 350                                 ((unsigned char *) buffer)[to++] = c;
 351                 }
 352                 sccb->header.length += to;
 353                 sccb->evbuf.length += to;
 354                 return from;
 355         } else {
 356                 memcpy(buffer, (const void *) msg, count);
 357                 sccb->header.length += count;
 358                 sccb->evbuf.length += count;
 359                 return count;
 360         }
 361 }
 362
 363 /*
 364  * Emit buffer after having waited long enough for more data to arrive.
 365  */
 366 static void
 367 sclp_vt220_timeout(unsigned long data)
 368 {
 369         sclp_vt220_emit_current();
 370 }
 371
 372 #define BUFFER_MAX_DELAY        HZ/2
 373
 374 /*
 375  * Internal implementation of the write function. Write COUNT bytes of data
 376  * from memory at BUF
 377  * to the SCLP interface. In case that the data does not fit into the current
 378  * write buffer, emit the current one and allocate a new one. If there are no
 379  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 380  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 381  * otherwise the user has to explicitly call the flush function.
 382  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 383  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 384  * of bytes written.
 385  */
 386 static int
 387 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 388                    int convertlf)
 389 {
 390         unsigned long flags;
 391         void *page;
 392         int written;
 393         int overall_written;
 394
 395         if (count <= 0)
 396                 return 0;
 397         overall_written = 0;
 398         spin_lock_irqsave(&sclp_vt220_lock, flags);
 399         do {
 400                 /* Create a sclp output buffer if none exists yet */
 401                 if (sclp_vt220_current_request == NULL) {
 402                         while (list_empty(&sclp_vt220_empty)) {
 403                                 spin_unlock_irqrestore(&sclp_vt220_lock,
 404                                                        flags);
 405                                 if (in_interrupt())
 406                                         sclp_sync_wait();
 407                                 else
 408                                         wait_event(sclp_vt220_waitq,
 409                                                 !list_empty(&sclp_vt220_empty));
 410                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 411                         }
 412                         page = (void *) sclp_vt220_empty.next;
 413                         list_del((struct list_head *) page);
 414                         sclp_vt220_current_request =
 415                                 sclp_vt220_initialize_page(page);
 416                 }
 417                 /* Try to write the string to the current request buffer */
 418                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 419                                              buf, count, convertlf);
 420                 overall_written += written;
 421                 if (written == count)
 422                         break;
 423                 /*
 424                  * Not all characters could be written to the current
 425                  * output buffer. Emit the buffer, create a new buffer
 426                  * and then output the rest of the string.
 427                  */
 428                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 429                 sclp_vt220_emit_current();
 430                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 431                 buf += written;
 432                 count -= written;
 433         } while (count > 0);
 434         /* Setup timer to output current console buffer after some time */
 435         if (sclp_vt220_current_request != NULL &&
 436             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 437                 sclp_vt220_timer.function = sclp_vt220_timeout;
 438                 sclp_vt220_timer.data = 0UL;
 439                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 440                 add_timer(&sclp_vt220_timer);
 441         }
 442         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 443         return overall_written;
 444 }
 445
 446 /*
 447  * This routine is called by the kernel to write a series of
 448  * characters to the tty device.  The characters may come from
 449  * user space or kernel space.  This routine will return the
 450  * number of characters actually accepted for writing.
 451  */
 452 static int
 453 sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
 454 {
 455         return __sclp_vt220_write(buf, count, 1, 0);
 456 }
 457
 458 #define SCLP_VT220_SESSION_ENDED        0x01
 459 #define SCLP_VT220_SESSION_STARTED      0x80
 460 #define SCLP_VT220_SESSION_DATA         0x00
 461
 462 /*
 463  * Called by the SCLP to report incoming event buffers.
 464  */
 465 static void
 466 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 467 {
 468         char *buffer;
 469         unsigned int count;
 470
 471         /* Ignore input if device is not open */
 472         if (sclp_vt220_tty == NULL)
 473                 return;
 474
 475         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 476         count = evbuf->length - sizeof(struct evbuf_header);
 477
 478         switch (*buffer) {
 479         case SCLP_VT220_SESSION_ENDED:
 480         case SCLP_VT220_SESSION_STARTED:
 481                 break;
 482         case SCLP_VT220_SESSION_DATA:
 483                 /* Send input to line discipline */
 484                 buffer++;
 485                 count--;
 486                 tty_insert_flip_string(sclp_vt220_tty, buffer, count);
 487                 tty_flip_buffer_push(sclp_vt220_tty);
 488                 break;
 489         }
 490 }
 491
 492 /*
 493  * This routine is called when a particular tty device is opened.
 494  */
 495 static int
 496 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 497 {
 498         if (tty->count == 1) {
 499                 sclp_vt220_tty = tty;
 500                 tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
 501                 if (tty->driver_data == NULL)
 502                         return -ENOMEM;
 503                 tty->low_latency = 0;
 504         }
 505         return 0;
 506 }
 507
 508 /*
 509  * This routine is called when a particular tty device is closed.
 510  */
 511 static void
 512 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 513 {
 514         if (tty->count == 1) {
 515                 sclp_vt220_tty = NULL;
 516                 kfree(tty->driver_data);
 517                 tty->driver_data = NULL;
 518         }
 519 }
 520
 521 /*
 522  * This routine is called by the kernel to write a single
 523  * character to the tty device.  If the kernel uses this routine,
 524  * it must call the flush_chars() routine (if defined) when it is
 525  * done stuffing characters into the driver.
 526  *
 527  * NOTE: include/linux/tty_driver.h specifies that a character should be
 528  * ignored if there is no room in the queue. This driver implements a different
 529  * semantic in that it will block when there is no more room left.
 530  */
 531 static void
 532 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 533 {
 534         __sclp_vt220_write(&ch, 1, 0, 0);
 535 }
 536
 537 /*
 538  * This routine is called by the kernel after it has written a
 539  * series of characters to the tty device using put_char().
 540  */
 541 static void
 542 sclp_vt220_flush_chars(struct tty_struct *tty)
 543 {
 544         if (sclp_vt220_outqueue_count == 0)
 545                 sclp_vt220_emit_current();
 546         else
 547                 sclp_vt220_flush_later = 1;
 548 }
 549
 550 /*
 551  * This routine returns the numbers of characters the tty driver
 552  * will accept for queuing to be written.  This number is subject
 553  * to change as output buffers get emptied, or if the output flow
 554  * control is acted.
 555  */
 556 static int
 557 sclp_vt220_write_room(struct tty_struct *tty)
 558 {
 559         unsigned long flags;
 560         struct list_head *l;
 561         int count;
 562
 563         spin_lock_irqsave(&sclp_vt220_lock, flags);
 564         count = 0;
 565         if (sclp_vt220_current_request != NULL)
 566                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 567         list_for_each(l, &sclp_vt220_empty)
 568                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 569         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 570         return count;
 571 }
 572
 573 /*
 574  * Return number of buffered chars.
 575  */
 576 static int
 577 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 578 {
 579         unsigned long flags;
 580         struct list_head *l;
 581         struct sclp_vt220_request *r;
 582         int count;
 583
 584         spin_lock_irqsave(&sclp_vt220_lock, flags);
 585         count = 0;
 586         if (sclp_vt220_current_request != NULL)
 587                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 588         list_for_each(l, &sclp_vt220_outqueue) {
 589                 r = list_entry(l, struct sclp_vt220_request, list);
 590                 count += sclp_vt220_chars_stored(r);
 591         }
 592         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 593         return count;
 594 }
 595
 596 static void
 597 __sclp_vt220_flush_buffer(void)
 598 {
 599         unsigned long flags;
 600
 601         sclp_vt220_emit_current();
 602         spin_lock_irqsave(&sclp_vt220_lock, flags);
 603         if (timer_pending(&sclp_vt220_timer))
 604                 del_timer(&sclp_vt220_timer);
 605         while (sclp_vt220_outqueue_count > 0) {
 606                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 607                 sclp_sync_wait();
 608                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 609         }
 610         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 611 }
 612
 613 /*
 614  * Pass on all buffers to the hardware. Return only when there are no more
 615  * buffers pending.
 616  */
 617 static void
 618 sclp_vt220_flush_buffer(struct tty_struct *tty)
 619 {
 620         sclp_vt220_emit_current();
 621 }
 622
 623 /*
 624  * Initialize all relevant components and register driver with system.
 625  */
 626 static int
 627 __sclp_vt220_init(int early)
 628 {
 629         void *page;
 630         int i;
 631
 632         if (sclp_vt220_initialized)
 633                 return 0;
 634         sclp_vt220_initialized = 1;
 635         spin_lock_init(&sclp_vt220_lock);
 636         INIT_LIST_HEAD(&sclp_vt220_empty);
 637         INIT_LIST_HEAD(&sclp_vt220_outqueue);
 638         init_waitqueue_head(&sclp_vt220_waitq);
 639         init_timer(&sclp_vt220_timer);
 640         sclp_vt220_current_request = NULL;
 641         sclp_vt220_buffered_chars = 0;
 642         sclp_vt220_outqueue_count = 0;
 643         sclp_vt220_tty = NULL;
 644         sclp_vt220_flush_later = 0;
 645
 646         /* Allocate pages for output buffering */
 647         for (i = 0; i < (early ? MAX_CONSOLE_PAGES : MAX_KMEM_PAGES); i++) {
 648                 if (early)
 649                         page = alloc_bootmem_low_pages(PAGE_SIZE);
 650                 else
 651                         page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 652                 if (!page)
 653                         return -ENOMEM;
 654                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 655         }
 656         return 0;
 657 }
 658
 659 static struct tty_operations sclp_vt220_ops = {
 660         .open = sclp_vt220_open,
 661         .close = sclp_vt220_close,
 662         .write = sclp_vt220_write,
 663         .put_char = sclp_vt220_put_char,
 664         .flush_chars = sclp_vt220_flush_chars,
 665         .write_room = sclp_vt220_write_room,
 666         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 667         .flush_buffer = sclp_vt220_flush_buffer
 668 };
 669
 670 /*
 671  * Register driver with SCLP and Linux and initialize internal tty structures.
 672  */
 673 int __init
 674 sclp_vt220_tty_init(void)
 675 {
 676         struct tty_driver *driver;
 677         int rc;
 678
 679         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 680          * symmetry between VM and LPAR systems regarding ttyS1. */
 681         driver = alloc_tty_driver(1);
 682         if (!driver)
 683                 return -ENOMEM;
 684         rc = __sclp_vt220_init(0);
 685         if (rc) {
 686                 put_tty_driver(driver);
 687                 return rc;
 688         }
 689         rc = sclp_register(&sclp_vt220_register);
 690         if (rc) {
 691                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 692                        "could not register tty - "
 693                        "sclp_register returned %d\n", rc);
 694                 put_tty_driver(driver);
 695                 return rc;
 696         }
 697
 698         driver->owner = THIS_MODULE;
 699         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 700         driver->name = SCLP_VT220_DEVICE_NAME;
 701         driver->major = SCLP_VT220_MAJOR;
 702         driver->minor_start = SCLP_VT220_MINOR;
 703         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 704         driver->subtype = SYSTEM_TYPE_TTY;
 705         driver->init_termios = tty_std_termios;
 706         driver->flags = TTY_DRIVER_REAL_RAW;
 707         tty_set_operations(driver, &sclp_vt220_ops);
 708
 709         rc = tty_register_driver(driver);
 710         if (rc) {
 711                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 712                        "could not register tty - "
 713                        "tty_register_driver returned %d\n", rc);
 714                 put_tty_driver(driver);
 715                 return rc;
 716         }
 717         sclp_vt220_driver = driver;
 718         return 0;
 719 }
 720
 721 module_init(sclp_vt220_tty_init);
 722
 723 #ifdef CONFIG_SCLP_VT220_CONSOLE
 724
 725 static void
 726 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 727 {
 728         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1);
 729 }
 730
 731 static struct tty_driver *
 732 sclp_vt220_con_device(struct console *c, int *index)
 733 {
 734         *index = 0;
 735         return sclp_vt220_driver;
 736 }
 737
 738 /*
 739  * This routine is called from panic when the kernel is going to give up.
 740  * We have to make sure that all buffers will be flushed to the SCLP.
 741  * Note that this function may be called from within an interrupt context.
 742  */
 743 static void
 744 sclp_vt220_con_unblank(void)
 745 {
 746         __sclp_vt220_flush_buffer();
 747 }
 748
 749 /* Structure needed to register with printk */
 750 static struct console sclp_vt220_console =
 751 {
 752         .name = SCLP_VT220_CONSOLE_NAME,
 753         .write = sclp_vt220_con_write,
 754         .device = sclp_vt220_con_device,
 755         .unblank = sclp_vt220_con_unblank,
 756         .flags = CON_PRINTBUFFER,
 757         .index = SCLP_VT220_CONSOLE_INDEX
 758 };
 759
 760 static int __init
 761 sclp_vt220_con_init(void)
 762 {
 763         int rc;
 764
 765         if (!CONSOLE_IS_SCLP)
 766                 return 0;
 767         rc = __sclp_vt220_init(1);
 768         if (rc)
 769                 return rc;
 770         /* Attach linux console */
 771         register_console(&sclp_vt220_console);
 772         return 0;
 773 }
 774
 775 console_initcall(sclp_vt220_con_init);
 776 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 777