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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/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/sched.h>
  20 #include <linux/errno.h>
  21 #include <linux/mm.h>
  22 #include <linux/major.h>
  23 #include <linux/console.h>
  24 #include <linux/kdev_t.h>
  25 #include <linux/bootmem.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/init.h>
  28 #include <asm/uaccess.h>
  29 #include "sclp.h"
  30
  31 #define SCLP_VT220_PRINT_HEADER         "sclp vt220 tty driver: "
  32 #define SCLP_VT220_MAJOR                TTY_MAJOR
  33 #define SCLP_VT220_MINOR                65
  34 #define SCLP_VT220_DRIVER_NAME          "sclp_vt220"
  35 #define SCLP_VT220_DEVICE_NAME          "ttysclp"
  36 #define SCLP_VT220_CONSOLE_NAME         "ttyS"
  37 #define SCLP_VT220_CONSOLE_INDEX        1       /* console=ttyS1 */
  38 #define SCLP_VT220_BUF_SIZE             80
  39
  40 /* Representation of a single write request */
  41 struct sclp_vt220_request {
  42         struct list_head list;
  43         struct sclp_req sclp_req;
  44         int retry_count;
  45 };
  46
  47 /* VT220 SCCB */
  48 struct sclp_vt220_sccb {
  49         struct sccb_header header;
  50         struct evbuf_header evbuf;
  51 };
  52
  53 #define SCLP_VT220_MAX_CHARS_PER_BUFFER (PAGE_SIZE - \
  54                                          sizeof(struct sclp_vt220_request) - \
  55                                          sizeof(struct sclp_vt220_sccb))
  56
  57 /* Structures and data needed to register tty driver */
  58 static struct tty_driver *sclp_vt220_driver;
  59
  60 /* The tty_struct that the kernel associated with us */
  61 static struct tty_struct *sclp_vt220_tty;
  62
  63 /* Lock to protect internal data from concurrent access */
  64 static spinlock_t sclp_vt220_lock;
  65
  66 /* List of empty pages to be used as write request buffers */
  67 static struct list_head sclp_vt220_empty;
  68
  69 /* List of pending requests */
  70 static struct list_head sclp_vt220_outqueue;
  71
  72 /* Number of requests in outqueue */
  73 static int sclp_vt220_outqueue_count;
  74
  75 /* Wait queue used to delay write requests while we've run out of buffers */
  76 static wait_queue_head_t sclp_vt220_waitq;
  77
  78 /* Timer used for delaying write requests to merge subsequent messages into
  79  * a single buffer */
  80 static struct timer_list sclp_vt220_timer;
  81
  82 /* Pointer to current request buffer which has been partially filled but not
  83  * yet sent */
  84 static struct sclp_vt220_request *sclp_vt220_current_request;
  85
  86 /* Number of characters in current request buffer */
  87 static int sclp_vt220_buffered_chars;
  88
  89 /* Flag indicating whether this driver has already been initialized */
  90 static int sclp_vt220_initialized = 0;
  91
  92 /* Flag indicating that sclp_vt220_current_request should really
  93  * have been already queued but wasn't because the SCLP was processing
  94  * another buffer */
  95 static int sclp_vt220_flush_later;
  96
  97 static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
  98 static int __sclp_vt220_emit(struct sclp_vt220_request *request);
  99 static void sclp_vt220_emit_current(void);
 100
 101 /* Registration structure for our interest in SCLP event buffers */
 102 static struct sclp_register sclp_vt220_register = {
 103         .send_mask              = EvTyp_VT220Msg_Mask,
 104         .receive_mask           = EvTyp_VT220Msg_Mask,
 105         .state_change_fn        = NULL,
 106         .receiver_fn            = sclp_vt220_receiver_fn
 107 };
 108
 109
 110 /*
 111  * Put provided request buffer back into queue and check emit pending
 112  * buffers if necessary.
 113  */
 114 static void
 115 sclp_vt220_process_queue(struct sclp_vt220_request *request)
 116 {
 117         unsigned long flags;
 118         void *page;
 119
 120         do {
 121                 /* Put buffer back to list of empty buffers */
 122                 page = request->sclp_req.sccb;
 123                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 124                 /* Move request from outqueue to empty queue */
 125                 list_del(&request->list);
 126                 sclp_vt220_outqueue_count--;
 127                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 128                 /* Check if there is a pending buffer on the out queue. */
 129                 request = NULL;
 130                 if (!list_empty(&sclp_vt220_outqueue))
 131                         request = list_entry(sclp_vt220_outqueue.next,
 132                                              struct sclp_vt220_request, list);
 133                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 134         } while (request && __sclp_vt220_emit(request));
 135         if (request == NULL && sclp_vt220_flush_later)
 136                 sclp_vt220_emit_current();
 137         wake_up(&sclp_vt220_waitq);
 138         /* Check if the tty needs a wake up call */
 139         if (sclp_vt220_tty != NULL) {
 140                 tty_wakeup(sclp_vt220_tty);
 141         }
 142 }
 143
 144 #define SCLP_BUFFER_MAX_RETRY           1
 145
 146 /*
 147  * Callback through which the result of a write request is reported by the
 148  * SCLP.
 149  */
 150 static void
 151 sclp_vt220_callback(struct sclp_req *request, void *data)
 152 {
 153         struct sclp_vt220_request *vt220_request;
 154         struct sclp_vt220_sccb *sccb;
 155
 156         vt220_request = (struct sclp_vt220_request *) data;
 157         if (request->status == SCLP_REQ_FAILED) {
 158                 sclp_vt220_process_queue(vt220_request);
 159                 return;
 160         }
 161         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
 162
 163         /* Check SCLP response code and choose suitable action  */
 164         switch (sccb->header.response_code) {
 165         case 0x0020 :
 166                 break;
 167
 168         case 0x05f0: /* Target resource in improper state */
 169                 break;
 170
 171         case 0x0340: /* Contained SCLP equipment check */
 172                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 173                         break;
 174                 /* Remove processed buffers and requeue rest */
 175                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 176                         /* Not all buffers were processed */
 177                         sccb->header.response_code = 0x0000;
 178                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 179                         if (sclp_add_request(request) == 0)
 180                                 return;
 181                 }
 182                 break;
 183
 184         case 0x0040: /* SCLP equipment check */
 185                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 186                         break;
 187                 sccb->header.response_code = 0x0000;
 188                 vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 189                 if (sclp_add_request(request) == 0)
 190                         return;
 191                 break;
 192
 193         default:
 194                 break;
 195         }
 196         sclp_vt220_process_queue(vt220_request);
 197 }
 198
 199 /*
 200  * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
 201  * otherwise.
 202  */
 203 static int
 204 __sclp_vt220_emit(struct sclp_vt220_request *request)
 205 {
 206         if (!(sclp_vt220_register.sclp_send_mask & EvTyp_VT220Msg_Mask)) {
 207                 request->sclp_req.status = SCLP_REQ_FAILED;
 208                 return -EIO;
 209         }
 210         request->sclp_req.command = SCLP_CMDW_WRITEDATA;
 211         request->sclp_req.status = SCLP_REQ_FILLED;
 212         request->sclp_req.callback = sclp_vt220_callback;
 213         request->sclp_req.callback_data = (void *) request;
 214
 215         return sclp_add_request(&request->sclp_req);
 216 }
 217
 218 /*
 219  * Queue and emit given request.
 220  */
 221 static void
 222 sclp_vt220_emit(struct sclp_vt220_request *request)
 223 {
 224         unsigned long flags;
 225         int count;
 226
 227         spin_lock_irqsave(&sclp_vt220_lock, flags);
 228         list_add_tail(&request->list, &sclp_vt220_outqueue);
 229         count = sclp_vt220_outqueue_count++;
 230         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 231         /* Emit only the first buffer immediately - callback takes care of
 232          * the rest */
 233         if (count == 0 && __sclp_vt220_emit(request))
 234                 sclp_vt220_process_queue(request);
 235 }
 236
 237 /*
 238  * Queue and emit current request. Return zero on success, non-zero otherwise.
 239  */
 240 static void
 241 sclp_vt220_emit_current(void)
 242 {
 243         unsigned long flags;
 244         struct sclp_vt220_request *request;
 245         struct sclp_vt220_sccb *sccb;
 246
 247         spin_lock_irqsave(&sclp_vt220_lock, flags);
 248         request = NULL;
 249         if (sclp_vt220_current_request != NULL) {
 250                 sccb = (struct sclp_vt220_sccb *)
 251                                 sclp_vt220_current_request->sclp_req.sccb;
 252                 /* Only emit buffers with content */
 253                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 254                         request = sclp_vt220_current_request;
 255                         sclp_vt220_current_request = NULL;
 256                         if (timer_pending(&sclp_vt220_timer))
 257                                 del_timer(&sclp_vt220_timer);
 258                 }
 259                 sclp_vt220_flush_later = 0;
 260         }
 261         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 262         if (request != NULL)
 263                 sclp_vt220_emit(request);
 264 }
 265
 266 #define SCLP_NORMAL_WRITE       0x00
 267
 268 /*
 269  * Helper function to initialize a page with the sclp request structure.
 270  */
 271 static struct sclp_vt220_request *
 272 sclp_vt220_initialize_page(void *page)
 273 {
 274         struct sclp_vt220_request *request;
 275         struct sclp_vt220_sccb *sccb;
 276
 277         /* Place request structure at end of page */
 278         request = ((struct sclp_vt220_request *)
 279                         ((addr_t) page + PAGE_SIZE)) - 1;
 280         request->retry_count = 0;
 281         request->sclp_req.sccb = page;
 282         /* SCCB goes at start of page */
 283         sccb = (struct sclp_vt220_sccb *) page;
 284         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
 285         sccb->header.length = sizeof(struct sclp_vt220_sccb);
 286         sccb->header.function_code = SCLP_NORMAL_WRITE;
 287         sccb->header.response_code = 0x0000;
 288         sccb->evbuf.type = EvTyp_VT220Msg;
 289         sccb->evbuf.length = sizeof(struct evbuf_header);
 290
 291         return request;
 292 }
 293
 294 static inline unsigned int
 295 sclp_vt220_space_left(struct sclp_vt220_request *request)
 296 {
 297         struct sclp_vt220_sccb *sccb;
 298         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 299         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
 300                sccb->header.length;
 301 }
 302
 303 static inline unsigned int
 304 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
 305 {
 306         struct sclp_vt220_sccb *sccb;
 307         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 308         return sccb->evbuf.length - sizeof(struct evbuf_header);
 309 }
 310
 311 /*
 312  * Add msg to buffer associated with request. Return the number of characters
 313  * added.
 314  */
 315 static int
 316 sclp_vt220_add_msg(struct sclp_vt220_request *request,
 317                    const unsigned char *msg, int count, int convertlf)
 318 {
 319         struct sclp_vt220_sccb *sccb;
 320         void *buffer;
 321         unsigned char c;
 322         int from;
 323         int to;
 324
 325         if (count > sclp_vt220_space_left(request))
 326                 count = sclp_vt220_space_left(request);
 327         if (count <= 0)
 328                 return 0;
 329
 330         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 331         buffer = (void *) ((addr_t) sccb + sccb->header.length);
 332
 333         if (convertlf) {
 334                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
 335                 for (from=0, to=0;
 336                      (from < count) && (to < sclp_vt220_space_left(request));
 337                      from++) {
 338                         /* Retrieve character */
 339                         c = msg[from];
 340                         /* Perform conversion */
 341                         if (c == 0x0a) {
 342                                 if (to + 1 < sclp_vt220_space_left(request)) {
 343                                         ((unsigned char *) buffer)[to++] = c;
 344                                         ((unsigned char *) buffer)[to++] = 0x0d;
 345                                 } else
 346                                         break;
 347
 348                         } else
 349                                 ((unsigned char *) buffer)[to++] = c;
 350                 }
 351                 sccb->header.length += to;
 352                 sccb->evbuf.length += to;
 353                 return from;
 354         } else {
 355                 memcpy(buffer, (const void *) msg, count);
 356                 sccb->header.length += count;
 357                 sccb->evbuf.length += count;
 358                 return count;
 359         }
 360 }
 361
 362 /*
 363  * Emit buffer after having waited long enough for more data to arrive.
 364  */
 365 static void
 366 sclp_vt220_timeout(unsigned long data)
 367 {
 368         sclp_vt220_emit_current();
 369 }
 370
 371 #define BUFFER_MAX_DELAY        HZ/2
 372
 373 /*
 374  * Internal implementation of the write function. Write COUNT bytes of data
 375  * from memory at BUF
 376  * to the SCLP interface. In case that the data does not fit into the current
 377  * write buffer, emit the current one and allocate a new one. If there are no
 378  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 379  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 380  * otherwise the user has to explicitly call the flush function.
 381  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 382  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 383  * of bytes written.
 384  */
 385 static int
 386 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 387                    int convertlf)
 388 {
 389         unsigned long flags;
 390         void *page;
 391         int written;
 392         int overall_written;
 393
 394         if (count <= 0)
 395                 return 0;
 396         overall_written = 0;
 397         spin_lock_irqsave(&sclp_vt220_lock, flags);
 398         do {
 399                 /* Create a sclp output buffer if none exists yet */
 400                 if (sclp_vt220_current_request == NULL) {
 401                         while (list_empty(&sclp_vt220_empty)) {
 402                                 spin_unlock_irqrestore(&sclp_vt220_lock,
 403                                                        flags);
 404                                 if (in_interrupt())
 405                                         sclp_sync_wait();
 406                                 else
 407                                         wait_event(sclp_vt220_waitq,
 408                                                 !list_empty(&sclp_vt220_empty));
 409                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 410                         }
 411                         page = (void *) sclp_vt220_empty.next;
 412                         list_del((struct list_head *) page);
 413                         sclp_vt220_current_request =
 414                                 sclp_vt220_initialize_page(page);
 415                 }
 416                 /* Try to write the string to the current request buffer */
 417                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 418                                              buf, count, convertlf);
 419                 overall_written += written;
 420                 if (written == count)
 421                         break;
 422                 /*
 423                  * Not all characters could be written to the current
 424                  * output buffer. Emit the buffer, create a new buffer
 425                  * and then output the rest of the string.
 426                  */
 427                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 428                 sclp_vt220_emit_current();
 429                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 430                 buf += written;
 431                 count -= written;
 432         } while (count > 0);
 433         /* Setup timer to output current console buffer after some time */
 434         if (sclp_vt220_current_request != NULL &&
 435             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 436                 sclp_vt220_timer.function = sclp_vt220_timeout;
 437                 sclp_vt220_timer.data = 0UL;
 438                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 439                 add_timer(&sclp_vt220_timer);
 440         }
 441         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 442         return overall_written;
 443 }
 444
 445 /*
 446  * This routine is called by the kernel to write a series of
 447  * characters to the tty device.  The characters may come from
 448  * user space or kernel space.  This routine will return the
 449  * number of characters actually accepted for writing.
 450  */
 451 static int
 452 sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
 453 {
 454         return __sclp_vt220_write(buf, count, 1, 0);
 455 }
 456
 457 #define SCLP_VT220_SESSION_ENDED        0x01
 458 #define SCLP_VT220_SESSION_STARTED      0x80
 459 #define SCLP_VT220_SESSION_DATA         0x00
 460
 461 /*
 462  * Called by the SCLP to report incoming event buffers.
 463  */
 464 static void
 465 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 466 {
 467         char *buffer;
 468         unsigned int count;
 469
 470         /* Ignore input if device is not open */
 471         if (sclp_vt220_tty == NULL)
 472                 return;
 473
 474         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 475         count = evbuf->length - sizeof(struct evbuf_header);
 476
 477         switch (*buffer) {
 478         case SCLP_VT220_SESSION_ENDED:
 479         case SCLP_VT220_SESSION_STARTED:
 480                 break;
 481         case SCLP_VT220_SESSION_DATA:
 482                 /* Send input to line discipline */
 483                 buffer++;
 484                 count--;
 485                 tty_insert_flip_string(sclp_vt220_tty, buffer, count);
 486                 tty_flip_buffer_push(sclp_vt220_tty);
 487                 break;
 488         }
 489 }
 490
 491 /*
 492  * This routine is called when a particular tty device is opened.
 493  */
 494 static int
 495 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 496 {
 497         if (tty->count == 1) {
 498                 sclp_vt220_tty = tty;
 499                 tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
 500                 if (tty->driver_data == NULL)
 501                         return -ENOMEM;
 502                 tty->low_latency = 0;
 503         }
 504         return 0;
 505 }
 506
 507 /*
 508  * This routine is called when a particular tty device is closed.
 509  */
 510 static void
 511 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 512 {
 513         if (tty->count == 1) {
 514                 sclp_vt220_tty = NULL;
 515                 kfree(tty->driver_data);
 516                 tty->driver_data = NULL;
 517         }
 518 }
 519
 520 /*
 521  * This routine is called by the kernel to write a single
 522  * character to the tty device.  If the kernel uses this routine,
 523  * it must call the flush_chars() routine (if defined) when it is
 524  * done stuffing characters into the driver.
 525  *
 526  * NOTE: include/linux/tty_driver.h specifies that a character should be
 527  * ignored if there is no room in the queue. This driver implements a different
 528  * semantic in that it will block when there is no more room left.
 529  */
 530 static void
 531 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 532 {
 533         __sclp_vt220_write(&ch, 1, 0, 0);
 534 }
 535
 536 /*
 537  * This routine is called by the kernel after it has written a
 538  * series of characters to the tty device using put_char().
 539  */
 540 static void
 541 sclp_vt220_flush_chars(struct tty_struct *tty)
 542 {
 543         if (sclp_vt220_outqueue_count == 0)
 544                 sclp_vt220_emit_current();
 545         else
 546                 sclp_vt220_flush_later = 1;
 547 }
 548
 549 /*
 550  * This routine returns the numbers of characters the tty driver
 551  * will accept for queuing to be written.  This number is subject
 552  * to change as output buffers get emptied, or if the output flow
 553  * control is acted.
 554  */
 555 static int
 556 sclp_vt220_write_room(struct tty_struct *tty)
 557 {
 558         unsigned long flags;
 559         struct list_head *l;
 560         int count;
 561
 562         spin_lock_irqsave(&sclp_vt220_lock, flags);
 563         count = 0;
 564         if (sclp_vt220_current_request != NULL)
 565                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 566         list_for_each(l, &sclp_vt220_empty)
 567                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 568         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 569         return count;
 570 }
 571
 572 /*
 573  * Return number of buffered chars.
 574  */
 575 static int
 576 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 577 {
 578         unsigned long flags;
 579         struct list_head *l;
 580         struct sclp_vt220_request *r;
 581         int count;
 582
 583         spin_lock_irqsave(&sclp_vt220_lock, flags);
 584         count = 0;
 585         if (sclp_vt220_current_request != NULL)
 586                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 587         list_for_each(l, &sclp_vt220_outqueue) {
 588                 r = list_entry(l, struct sclp_vt220_request, list);
 589                 count += sclp_vt220_chars_stored(r);
 590         }
 591         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 592         return count;
 593 }
 594
 595 static void
 596 __sclp_vt220_flush_buffer(void)
 597 {
 598         unsigned long flags;
 599
 600         sclp_vt220_emit_current();
 601         spin_lock_irqsave(&sclp_vt220_lock, flags);
 602         if (timer_pending(&sclp_vt220_timer))
 603                 del_timer(&sclp_vt220_timer);
 604         while (sclp_vt220_outqueue_count > 0) {
 605                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 606                 sclp_sync_wait();
 607                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 608         }
 609         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 610 }
 611
 612 /*
 613  * Pass on all buffers to the hardware. Return only when there are no more
 614  * buffers pending.
 615  */
 616 static void
 617 sclp_vt220_flush_buffer(struct tty_struct *tty)
 618 {
 619         sclp_vt220_emit_current();
 620 }
 621
 622 /*
 623  * Initialize all relevant components and register driver with system.
 624  */
 625 static int
 626 __sclp_vt220_init(int early)
 627 {
 628         void *page;
 629         int i;
 630
 631         if (sclp_vt220_initialized)
 632                 return 0;
 633         sclp_vt220_initialized = 1;
 634         spin_lock_init(&sclp_vt220_lock);
 635         INIT_LIST_HEAD(&sclp_vt220_empty);
 636         INIT_LIST_HEAD(&sclp_vt220_outqueue);
 637         init_waitqueue_head(&sclp_vt220_waitq);
 638         init_timer(&sclp_vt220_timer);
 639         sclp_vt220_current_request = NULL;
 640         sclp_vt220_buffered_chars = 0;
 641         sclp_vt220_outqueue_count = 0;
 642         sclp_vt220_tty = NULL;
 643         sclp_vt220_flush_later = 0;
 644
 645         /* Allocate pages for output buffering */
 646         for (i = 0; i < (early ? MAX_CONSOLE_PAGES : MAX_KMEM_PAGES); i++) {
 647                 if (early)
 648                         page = alloc_bootmem_low_pages(PAGE_SIZE);
 649                 else
 650                         page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 651                 if (!page)
 652                         return -ENOMEM;
 653                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 654         }
 655         return 0;
 656 }
 657
 658 static struct tty_operations sclp_vt220_ops = {
 659         .open = sclp_vt220_open,
 660         .close = sclp_vt220_close,
 661         .write = sclp_vt220_write,
 662         .put_char = sclp_vt220_put_char,
 663         .flush_chars = sclp_vt220_flush_chars,
 664         .write_room = sclp_vt220_write_room,
 665         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 666         .flush_buffer = sclp_vt220_flush_buffer
 667 };
 668
 669 /*
 670  * Register driver with SCLP and Linux and initialize internal tty structures.
 671  */
 672 int __init
 673 sclp_vt220_tty_init(void)
 674 {
 675         struct tty_driver *driver;
 676         int rc;
 677
 678         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 679          * symmetry between VM and LPAR systems regarding ttyS1. */
 680         driver = alloc_tty_driver(1);
 681         if (!driver)
 682                 return -ENOMEM;
 683         rc = __sclp_vt220_init(0);
 684         if (rc) {
 685                 put_tty_driver(driver);
 686                 return rc;
 687         }
 688         rc = sclp_register(&sclp_vt220_register);
 689         if (rc) {
 690                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 691                        "could not register tty - "
 692                        "sclp_register returned %d\n", rc);
 693                 put_tty_driver(driver);
 694                 return rc;
 695         }
 696
 697         driver->owner = THIS_MODULE;
 698         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 699         driver->name = SCLP_VT220_DEVICE_NAME;
 700         driver->major = SCLP_VT220_MAJOR;
 701         driver->minor_start = SCLP_VT220_MINOR;
 702         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 703         driver->subtype = SYSTEM_TYPE_TTY;
 704         driver->init_termios = tty_std_termios;
 705         driver->flags = TTY_DRIVER_REAL_RAW;
 706         tty_set_operations(driver, &sclp_vt220_ops);
 707
 708         rc = tty_register_driver(driver);
 709         if (rc) {
 710                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 711                        "could not register tty - "
 712                        "tty_register_driver returned %d\n", rc);
 713                 put_tty_driver(driver);
 714                 return rc;
 715         }
 716         sclp_vt220_driver = driver;
 717         return 0;
 718 }
 719
 720 module_init(sclp_vt220_tty_init);
 721
 722 #ifdef CONFIG_SCLP_VT220_CONSOLE
 723
 724 static void
 725 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 726 {
 727         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1);
 728 }
 729
 730 static struct tty_driver *
 731 sclp_vt220_con_device(struct console *c, int *index)
 732 {
 733         *index = 0;
 734         return sclp_vt220_driver;
 735 }
 736
 737 /*
 738  * This routine is called from panic when the kernel is going to give up.
 739  * We have to make sure that all buffers will be flushed to the SCLP.
 740  * Note that this function may be called from within an interrupt context.
 741  */
 742 static void
 743 sclp_vt220_con_unblank(void)
 744 {
 745         __sclp_vt220_flush_buffer();
 746 }
 747
 748 /* Structure needed to register with printk */
 749 static struct console sclp_vt220_console =
 750 {
 751         .name = SCLP_VT220_CONSOLE_NAME,
 752         .write = sclp_vt220_con_write,
 753         .device = sclp_vt220_con_device,
 754         .unblank = sclp_vt220_con_unblank,
 755         .flags = CON_PRINTBUFFER,
 756         .index = SCLP_VT220_CONSOLE_INDEX
 757 };
 758
 759 static int __init
 760 sclp_vt220_con_init(void)
 761 {
 762         int rc;
 763
 764         if (!CONSOLE_IS_SCLP)
 765                 return 0;
 766         rc = __sclp_vt220_init(1);
 767         if (rc)
 768                 return rc;
 769         /* Attach linux console */
 770         register_console(&sclp_vt220_console);
 771         return 0;
 772 }
 773
 774 console_initcall(sclp_vt220_con_init);
 775 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 776