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   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 /* Wait queue used to delay write requests while we've run out of buffers */
  75 static wait_queue_head_t sclp_vt220_waitq;
  76
  77 /* Timer used for delaying write requests to merge subsequent messages into
  78  * a single buffer */
  79 static struct timer_list sclp_vt220_timer;
  80
  81 /* Pointer to current request buffer which has been partially filled but not
  82  * yet sent */
  83 static struct sclp_vt220_request *sclp_vt220_current_request;
  84
  85 /* Number of characters in current request buffer */
  86 static int sclp_vt220_buffered_chars;
  87
  88 /* Flag indicating whether this driver has already been initialized */
  89 static int sclp_vt220_initialized = 0;
  90
  91 /* Flag indicating that sclp_vt220_current_request should really
  92  * have been already queued but wasn't because the SCLP was processing
  93  * another buffer */
  94 static int sclp_vt220_flush_later;
  95
  96 static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
  97 static int __sclp_vt220_emit(struct sclp_vt220_request *request);
  98 static void sclp_vt220_emit_current(void);
  99
 100 /* Registration structure for our interest in SCLP event buffers */
 101 static struct sclp_register sclp_vt220_register = {
 102         .send_mask              = EVTYP_VT220MSG_MASK,
 103         .receive_mask           = EVTYP_VT220MSG_MASK,
 104         .state_change_fn        = NULL,
 105         .receiver_fn            = sclp_vt220_receiver_fn
 106 };
 107
 108
 109 /*
 110  * Put provided request buffer back into queue and check emit pending
 111  * buffers if necessary.
 112  */
 113 static void
 114 sclp_vt220_process_queue(struct sclp_vt220_request *request)
 115 {
 116         unsigned long flags;
 117         void *page;
 118
 119         do {
 120                 /* Put buffer back to list of empty buffers */
 121                 page = request->sclp_req.sccb;
 122                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 123                 /* Move request from outqueue to empty queue */
 124                 list_del(&request->list);
 125                 sclp_vt220_outqueue_count--;
 126                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 127                 /* Check if there is a pending buffer on the out queue. */
 128                 request = NULL;
 129                 if (!list_empty(&sclp_vt220_outqueue))
 130                         request = list_entry(sclp_vt220_outqueue.next,
 131                                              struct sclp_vt220_request, list);
 132                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 133         } while (request && __sclp_vt220_emit(request));
 134         if (request == NULL && sclp_vt220_flush_later)
 135                 sclp_vt220_emit_current();
 136         wake_up(&sclp_vt220_waitq);
 137         /* Check if the tty needs a wake up call */
 138         if (sclp_vt220_tty != NULL) {
 139                 tty_wakeup(sclp_vt220_tty);
 140         }
 141 }
 142
 143 #define SCLP_BUFFER_MAX_RETRY           1
 144
 145 /*
 146  * Callback through which the result of a write request is reported by the
 147  * SCLP.
 148  */
 149 static void
 150 sclp_vt220_callback(struct sclp_req *request, void *data)
 151 {
 152         struct sclp_vt220_request *vt220_request;
 153         struct sclp_vt220_sccb *sccb;
 154
 155         vt220_request = (struct sclp_vt220_request *) data;
 156         if (request->status == SCLP_REQ_FAILED) {
 157                 sclp_vt220_process_queue(vt220_request);
 158                 return;
 159         }
 160         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
 161
 162         /* Check SCLP response code and choose suitable action  */
 163         switch (sccb->header.response_code) {
 164         case 0x0020 :
 165                 break;
 166
 167         case 0x05f0: /* Target resource in improper state */
 168                 break;
 169
 170         case 0x0340: /* Contained SCLP equipment check */
 171                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 172                         break;
 173                 /* Remove processed buffers and requeue rest */
 174                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 175                         /* Not all buffers were processed */
 176                         sccb->header.response_code = 0x0000;
 177                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 178                         if (sclp_add_request(request) == 0)
 179                                 return;
 180                 }
 181                 break;
 182
 183         case 0x0040: /* SCLP equipment check */
 184                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 185                         break;
 186                 sccb->header.response_code = 0x0000;
 187                 vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 188                 if (sclp_add_request(request) == 0)
 189                         return;
 190                 break;
 191
 192         default:
 193                 break;
 194         }
 195         sclp_vt220_process_queue(vt220_request);
 196 }
 197
 198 /*
 199  * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
 200  * otherwise.
 201  */
 202 static int
 203 __sclp_vt220_emit(struct sclp_vt220_request *request)
 204 {
 205         if (!(sclp_vt220_register.sclp_receive_mask & EVTYP_VT220MSG_MASK)) {
 206                 request->sclp_req.status = SCLP_REQ_FAILED;
 207                 return -EIO;
 208         }
 209         request->sclp_req.command = SCLP_CMDW_WRITE_EVENT_DATA;
 210         request->sclp_req.status = SCLP_REQ_FILLED;
 211         request->sclp_req.callback = sclp_vt220_callback;
 212         request->sclp_req.callback_data = (void *) request;
 213
 214         return sclp_add_request(&request->sclp_req);
 215 }
 216
 217 /*
 218  * Queue and emit given request.
 219  */
 220 static void
 221 sclp_vt220_emit(struct sclp_vt220_request *request)
 222 {
 223         unsigned long flags;
 224         int count;
 225
 226         spin_lock_irqsave(&sclp_vt220_lock, flags);
 227         list_add_tail(&request->list, &sclp_vt220_outqueue);
 228         count = sclp_vt220_outqueue_count++;
 229         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 230         /* Emit only the first buffer immediately - callback takes care of
 231          * the rest */
 232         if (count == 0 && __sclp_vt220_emit(request))
 233                 sclp_vt220_process_queue(request);
 234 }
 235
 236 /*
 237  * Queue and emit current request. Return zero on success, non-zero otherwise.
 238  */
 239 static void
 240 sclp_vt220_emit_current(void)
 241 {
 242         unsigned long flags;
 243         struct sclp_vt220_request *request;
 244         struct sclp_vt220_sccb *sccb;
 245
 246         spin_lock_irqsave(&sclp_vt220_lock, flags);
 247         request = NULL;
 248         if (sclp_vt220_current_request != NULL) {
 249                 sccb = (struct sclp_vt220_sccb *)
 250                                 sclp_vt220_current_request->sclp_req.sccb;
 251                 /* Only emit buffers with content */
 252                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 253                         request = sclp_vt220_current_request;
 254                         sclp_vt220_current_request = NULL;
 255                         if (timer_pending(&sclp_vt220_timer))
 256                                 del_timer(&sclp_vt220_timer);
 257                 }
 258                 sclp_vt220_flush_later = 0;
 259         }
 260         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 261         if (request != NULL)
 262                 sclp_vt220_emit(request);
 263 }
 264
 265 #define SCLP_NORMAL_WRITE       0x00
 266
 267 /*
 268  * Helper function to initialize a page with the sclp request structure.
 269  */
 270 static struct sclp_vt220_request *
 271 sclp_vt220_initialize_page(void *page)
 272 {
 273         struct sclp_vt220_request *request;
 274         struct sclp_vt220_sccb *sccb;
 275
 276         /* Place request structure at end of page */
 277         request = ((struct sclp_vt220_request *)
 278                         ((addr_t) page + PAGE_SIZE)) - 1;
 279         request->retry_count = 0;
 280         request->sclp_req.sccb = page;
 281         /* SCCB goes at start of page */
 282         sccb = (struct sclp_vt220_sccb *) page;
 283         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
 284         sccb->header.length = sizeof(struct sclp_vt220_sccb);
 285         sccb->header.function_code = SCLP_NORMAL_WRITE;
 286         sccb->header.response_code = 0x0000;
 287         sccb->evbuf.type = EVTYP_VT220MSG;
 288         sccb->evbuf.length = sizeof(struct evbuf_header);
 289
 290         return request;
 291 }
 292
 293 static inline unsigned int
 294 sclp_vt220_space_left(struct sclp_vt220_request *request)
 295 {
 296         struct sclp_vt220_sccb *sccb;
 297         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 298         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
 299                sccb->header.length;
 300 }
 301
 302 static inline unsigned int
 303 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
 304 {
 305         struct sclp_vt220_sccb *sccb;
 306         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 307         return sccb->evbuf.length - sizeof(struct evbuf_header);
 308 }
 309
 310 /*
 311  * Add msg to buffer associated with request. Return the number of characters
 312  * added.
 313  */
 314 static int
 315 sclp_vt220_add_msg(struct sclp_vt220_request *request,
 316                    const unsigned char *msg, int count, int convertlf)
 317 {
 318         struct sclp_vt220_sccb *sccb;
 319         void *buffer;
 320         unsigned char c;
 321         int from;
 322         int to;
 323
 324         if (count > sclp_vt220_space_left(request))
 325                 count = sclp_vt220_space_left(request);
 326         if (count <= 0)
 327                 return 0;
 328
 329         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 330         buffer = (void *) ((addr_t) sccb + sccb->header.length);
 331
 332         if (convertlf) {
 333                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
 334                 for (from=0, to=0;
 335                      (from < count) && (to < sclp_vt220_space_left(request));
 336                      from++) {
 337                         /* Retrieve character */
 338                         c = msg[from];
 339                         /* Perform conversion */
 340                         if (c == 0x0a) {
 341                                 if (to + 1 < sclp_vt220_space_left(request)) {
 342                                         ((unsigned char *) buffer)[to++] = c;
 343                                         ((unsigned char *) buffer)[to++] = 0x0d;
 344                                 } else
 345                                         break;
 346
 347                         } else
 348                                 ((unsigned char *) buffer)[to++] = c;
 349                 }
 350                 sccb->header.length += to;
 351                 sccb->evbuf.length += to;
 352                 return from;
 353         } else {
 354                 memcpy(buffer, (const void *) msg, count);
 355                 sccb->header.length += count;
 356                 sccb->evbuf.length += count;
 357                 return count;
 358         }
 359 }
 360
 361 /*
 362  * Emit buffer after having waited long enough for more data to arrive.
 363  */
 364 static void
 365 sclp_vt220_timeout(unsigned long data)
 366 {
 367         sclp_vt220_emit_current();
 368 }
 369
 370 #define BUFFER_MAX_DELAY        HZ/20
 371
 372 /*
 373  * Internal implementation of the write function. Write COUNT bytes of data
 374  * from memory at BUF
 375  * to the SCLP interface. In case that the data does not fit into the current
 376  * write buffer, emit the current one and allocate a new one. If there are no
 377  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 378  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 379  * otherwise the user has to explicitly call the flush function.
 380  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 381  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 382  * of bytes written.
 383  */
 384 static int
 385 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 386                    int convertlf, int may_schedule)
 387 {
 388         unsigned long flags;
 389         void *page;
 390         int written;
 391         int overall_written;
 392
 393         if (count <= 0)
 394                 return 0;
 395         overall_written = 0;
 396         spin_lock_irqsave(&sclp_vt220_lock, flags);
 397         do {
 398                 /* Create a sclp output buffer if none exists yet */
 399                 if (sclp_vt220_current_request == NULL) {
 400                         while (list_empty(&sclp_vt220_empty)) {
 401                                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 402                                 if (in_interrupt() || !may_schedule)
 403                                         sclp_sync_wait();
 404                                 else
 405                                         wait_event(sclp_vt220_waitq,
 406                                                 !list_empty(&sclp_vt220_empty));
 407                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 408                         }
 409                         page = (void *) sclp_vt220_empty.next;
 410                         list_del((struct list_head *) page);
 411                         sclp_vt220_current_request =
 412                                 sclp_vt220_initialize_page(page);
 413                 }
 414                 /* Try to write the string to the current request buffer */
 415                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 416                                              buf, count, convertlf);
 417                 overall_written += written;
 418                 if (written == count)
 419                         break;
 420                 /*
 421                  * Not all characters could be written to the current
 422                  * output buffer. Emit the buffer, create a new buffer
 423                  * and then output the rest of the string.
 424                  */
 425                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 426                 sclp_vt220_emit_current();
 427                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 428                 buf += written;
 429                 count -= written;
 430         } while (count > 0);
 431         /* Setup timer to output current console buffer after some time */
 432         if (sclp_vt220_current_request != NULL &&
 433             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 434                 sclp_vt220_timer.function = sclp_vt220_timeout;
 435                 sclp_vt220_timer.data = 0UL;
 436                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 437                 add_timer(&sclp_vt220_timer);
 438         }
 439         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 440         return overall_written;
 441 }
 442
 443 /*
 444  * This routine is called by the kernel to write a series of
 445  * characters to the tty device.  The characters may come from
 446  * user space or kernel space.  This routine will return the
 447  * number of characters actually accepted for writing.
 448  */
 449 static int
 450 sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
 451 {
 452         return __sclp_vt220_write(buf, count, 1, 0, 1);
 453 }
 454
 455 #define SCLP_VT220_SESSION_ENDED        0x01
 456 #define SCLP_VT220_SESSION_STARTED      0x80
 457 #define SCLP_VT220_SESSION_DATA         0x00
 458
 459 /*
 460  * Called by the SCLP to report incoming event buffers.
 461  */
 462 static void
 463 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 464 {
 465         char *buffer;
 466         unsigned int count;
 467
 468         /* Ignore input if device is not open */
 469         if (sclp_vt220_tty == NULL)
 470                 return;
 471
 472         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 473         count = evbuf->length - sizeof(struct evbuf_header);
 474
 475         switch (*buffer) {
 476         case SCLP_VT220_SESSION_ENDED:
 477         case SCLP_VT220_SESSION_STARTED:
 478                 break;
 479         case SCLP_VT220_SESSION_DATA:
 480                 /* Send input to line discipline */
 481                 buffer++;
 482                 count--;
 483                 tty_insert_flip_string(sclp_vt220_tty, buffer, count);
 484                 tty_flip_buffer_push(sclp_vt220_tty);
 485                 break;
 486         }
 487 }
 488
 489 /*
 490  * This routine is called when a particular tty device is opened.
 491  */
 492 static int
 493 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 494 {
 495         if (tty->count == 1) {
 496                 sclp_vt220_tty = tty;
 497                 tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
 498                 if (tty->driver_data == NULL)
 499                         return -ENOMEM;
 500                 tty->low_latency = 0;
 501         }
 502         return 0;
 503 }
 504
 505 /*
 506  * This routine is called when a particular tty device is closed.
 507  */
 508 static void
 509 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 510 {
 511         if (tty->count == 1) {
 512                 sclp_vt220_tty = NULL;
 513                 kfree(tty->driver_data);
 514                 tty->driver_data = NULL;
 515         }
 516 }
 517
 518 /*
 519  * This routine is called by the kernel to write a single
 520  * character to the tty device.  If the kernel uses this routine,
 521  * it must call the flush_chars() routine (if defined) when it is
 522  * done stuffing characters into the driver.
 523  *
 524  * NOTE: include/linux/tty_driver.h specifies that a character should be
 525  * ignored if there is no room in the queue. This driver implements a different
 526  * semantic in that it will block when there is no more room left.
 527  */
 528 static void
 529 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 530 {
 531         __sclp_vt220_write(&ch, 1, 0, 0, 1);
 532 }
 533
 534 /*
 535  * This routine is called by the kernel after it has written a
 536  * series of characters to the tty device using put_char().
 537  */
 538 static void
 539 sclp_vt220_flush_chars(struct tty_struct *tty)
 540 {
 541         if (sclp_vt220_outqueue_count == 0)
 542                 sclp_vt220_emit_current();
 543         else
 544                 sclp_vt220_flush_later = 1;
 545 }
 546
 547 /*
 548  * This routine returns the numbers of characters the tty driver
 549  * will accept for queuing to be written.  This number is subject
 550  * to change as output buffers get emptied, or if the output flow
 551  * control is acted.
 552  */
 553 static int
 554 sclp_vt220_write_room(struct tty_struct *tty)
 555 {
 556         unsigned long flags;
 557         struct list_head *l;
 558         int count;
 559
 560         spin_lock_irqsave(&sclp_vt220_lock, flags);
 561         count = 0;
 562         if (sclp_vt220_current_request != NULL)
 563                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 564         list_for_each(l, &sclp_vt220_empty)
 565                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 566         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 567         return count;
 568 }
 569
 570 /*
 571  * Return number of buffered chars.
 572  */
 573 static int
 574 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 575 {
 576         unsigned long flags;
 577         struct list_head *l;
 578         struct sclp_vt220_request *r;
 579         int count;
 580
 581         spin_lock_irqsave(&sclp_vt220_lock, flags);
 582         count = 0;
 583         if (sclp_vt220_current_request != NULL)
 584                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 585         list_for_each(l, &sclp_vt220_outqueue) {
 586                 r = list_entry(l, struct sclp_vt220_request, list);
 587                 count += sclp_vt220_chars_stored(r);
 588         }
 589         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 590         return count;
 591 }
 592
 593 static void
 594 __sclp_vt220_flush_buffer(void)
 595 {
 596         unsigned long flags;
 597
 598         sclp_vt220_emit_current();
 599         spin_lock_irqsave(&sclp_vt220_lock, flags);
 600         if (timer_pending(&sclp_vt220_timer))
 601                 del_timer(&sclp_vt220_timer);
 602         while (sclp_vt220_outqueue_count > 0) {
 603                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 604                 sclp_sync_wait();
 605                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 606         }
 607         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 608 }
 609
 610 /*
 611  * Pass on all buffers to the hardware. Return only when there are no more
 612  * buffers pending.
 613  */
 614 static void
 615 sclp_vt220_flush_buffer(struct tty_struct *tty)
 616 {
 617         sclp_vt220_emit_current();
 618 }
 619
 620 /*
 621  * Initialize all relevant components and register driver with system.
 622  */
 623 static void __init __sclp_vt220_cleanup(void)
 624 {
 625         struct list_head *page, *p;
 626
 627         list_for_each_safe(page, p, &sclp_vt220_empty) {
 628                 list_del(page);
 629                 if (slab_is_available())
 630                         free_page((unsigned long) page);
 631                 else
 632                         free_bootmem((unsigned long) page, PAGE_SIZE);
 633         }
 634         if (!list_empty(&sclp_vt220_register.list))
 635                 sclp_unregister(&sclp_vt220_register);
 636         sclp_vt220_initialized = 0;
 637 }
 638
 639 static int __init __sclp_vt220_init(void)
 640 {
 641         void *page;
 642         int i;
 643         int num_pages;
 644         int rc;
 645
 646         if (sclp_vt220_initialized)
 647                 return 0;
 648         sclp_vt220_initialized = 1;
 649         spin_lock_init(&sclp_vt220_lock);
 650         INIT_LIST_HEAD(&sclp_vt220_empty);
 651         INIT_LIST_HEAD(&sclp_vt220_outqueue);
 652         init_waitqueue_head(&sclp_vt220_waitq);
 653         init_timer(&sclp_vt220_timer);
 654         sclp_vt220_current_request = NULL;
 655         sclp_vt220_buffered_chars = 0;
 656         sclp_vt220_outqueue_count = 0;
 657         sclp_vt220_tty = NULL;
 658         sclp_vt220_flush_later = 0;
 659
 660         /* Allocate pages for output buffering */
 661         num_pages = slab_is_available() ? MAX_KMEM_PAGES : MAX_CONSOLE_PAGES;
 662         for (i = 0; i < num_pages; i++) {
 663                 if (slab_is_available())
 664                         page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 665                 else
 666                         page = alloc_bootmem_low_pages(PAGE_SIZE);
 667                 if (!page) {
 668                         __sclp_vt220_cleanup();
 669                         return -ENOMEM;
 670                 }
 671                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 672         }
 673         rc = sclp_register(&sclp_vt220_register);
 674         if (rc) {
 675                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 676                        "could not register vt220 - "
 677                        "sclp_register returned %d\n", rc);
 678                 __sclp_vt220_cleanup();
 679         }
 680         return rc;
 681 }
 682
 683 static const struct tty_operations sclp_vt220_ops = {
 684         .open = sclp_vt220_open,
 685         .close = sclp_vt220_close,
 686         .write = sclp_vt220_write,
 687         .put_char = sclp_vt220_put_char,
 688         .flush_chars = sclp_vt220_flush_chars,
 689         .write_room = sclp_vt220_write_room,
 690         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 691         .flush_buffer = sclp_vt220_flush_buffer,
 692 };
 693
 694 /*
 695  * Register driver with SCLP and Linux and initialize internal tty structures.
 696  */
 697 static int __init sclp_vt220_tty_init(void)
 698 {
 699         struct tty_driver *driver;
 700         int rc;
 701         int cleanup;
 702
 703         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 704          * symmetry between VM and LPAR systems regarding ttyS1. */
 705         driver = alloc_tty_driver(1);
 706         if (!driver)
 707                 return -ENOMEM;
 708         cleanup = !sclp_vt220_initialized;
 709         rc = __sclp_vt220_init();
 710         if (rc)
 711                 goto out_driver;
 712
 713         driver->owner = THIS_MODULE;
 714         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 715         driver->name = SCLP_VT220_DEVICE_NAME;
 716         driver->major = SCLP_VT220_MAJOR;
 717         driver->minor_start = SCLP_VT220_MINOR;
 718         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 719         driver->subtype = SYSTEM_TYPE_TTY;
 720         driver->init_termios = tty_std_termios;
 721         driver->flags = TTY_DRIVER_REAL_RAW;
 722         tty_set_operations(driver, &sclp_vt220_ops);
 723
 724         rc = tty_register_driver(driver);
 725         if (rc) {
 726                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 727                        "could not register tty - "
 728                        "tty_register_driver returned %d\n", rc);
 729                 goto out_init;
 730         }
 731         sclp_vt220_driver = driver;
 732         return 0;
 733
 734 out_init:
 735         if (cleanup)
 736                 __sclp_vt220_cleanup();
 737 out_driver:
 738         put_tty_driver(driver);
 739         return rc;
 740 }
 741 __initcall(sclp_vt220_tty_init);
 742
 743 #ifdef CONFIG_SCLP_VT220_CONSOLE
 744
 745 static void
 746 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 747 {
 748         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1, 0);
 749 }
 750
 751 static struct tty_driver *
 752 sclp_vt220_con_device(struct console *c, int *index)
 753 {
 754         *index = 0;
 755         return sclp_vt220_driver;
 756 }
 757
 758 /*
 759  * This routine is called from panic when the kernel is going to give up.
 760  * We have to make sure that all buffers will be flushed to the SCLP.
 761  * Note that this function may be called from within an interrupt context.
 762  */
 763 static void
 764 sclp_vt220_con_unblank(void)
 765 {
 766         __sclp_vt220_flush_buffer();
 767 }
 768
 769 /* Structure needed to register with printk */
 770 static struct console sclp_vt220_console =
 771 {
 772         .name = SCLP_VT220_CONSOLE_NAME,
 773         .write = sclp_vt220_con_write,
 774         .device = sclp_vt220_con_device,
 775         .unblank = sclp_vt220_con_unblank,
 776         .flags = CON_PRINTBUFFER,
 777         .index = SCLP_VT220_CONSOLE_INDEX
 778 };
 779
 780 static int __init
 781 sclp_vt220_con_init(void)
 782 {
 783         int rc;
 784
 785         if (!CONSOLE_IS_SCLP)
 786                 return 0;
 787         rc = __sclp_vt220_init();
 788         if (rc)
 789                 return rc;
 790         /* Attach linux console */
 791         register_console(&sclp_vt220_console);
 792         return 0;
 793 }
 794
 795 console_initcall(sclp_vt220_con_init);
 796 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 797