drivers/s390/char/sclp_vt220.c

   1 /*
   2  * SCLP VT220 terminal driver.
   3  *
   4  * Copyright IBM Corp. 2003, 2009
   5  *
   6  * Author(s): Peter Oberparleiter <Peter.Oberparleiter@de.ibm.com>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/list.h>
  12 #include <linux/wait.h>
  13 #include <linux/timer.h>
  14 #include <linux/kernel.h>
  15 #include <linux/tty.h>
  16 #include <linux/tty_driver.h>
  17 #include <linux/tty_flip.h>
  18 #include <linux/errno.h>
  19 #include <linux/mm.h>
  20 #include <linux/major.h>
  21 #include <linux/console.h>
  22 #include <linux/kdev_t.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/init.h>
  25 #include <linux/reboot.h>
  26 #include <linux/slab.h>
  27
  28 #include <asm/uaccess.h>
  29 #include "sclp.h"
  30
  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 /* Suspend mode flag */
  72 static int sclp_vt220_suspended;
  73
  74 /* Flag that output queue is currently running */
  75 static int sclp_vt220_queue_running;
  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 /* Counter controlling core driver initialization. */
  89 static int __initdata sclp_vt220_init_count;
  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 void sclp_vt220_pm_event_fn(struct sclp_register *reg,
  98                                    enum sclp_pm_event sclp_pm_event);
  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         .pm_event_fn            = sclp_vt220_pm_event_fn,
 109 };
 110
 111
 112 /*
 113  * Put provided request buffer back into queue and check emit pending
 114  * buffers if necessary.
 115  */
 116 static void
 117 sclp_vt220_process_queue(struct sclp_vt220_request *request)
 118 {
 119         unsigned long flags;
 120         void *page;
 121
 122         do {
 123                 /* Put buffer back to list of empty buffers */
 124                 page = request->sclp_req.sccb;
 125                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 126                 /* Move request from outqueue to empty queue */
 127                 list_del(&request->list);
 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                 if (!request || sclp_vt220_suspended) {
 135                         sclp_vt220_queue_running = 0;
 136                         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 137                         break;
 138                 }
 139                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 140         } while (__sclp_vt220_emit(request));
 141         if (request == NULL && sclp_vt220_flush_later)
 142                 sclp_vt220_emit_current();
 143         /* Check if the tty needs a wake up call */
 144         if (sclp_vt220_tty != NULL) {
 145                 tty_wakeup(sclp_vt220_tty);
 146         }
 147 }
 148
 149 #define SCLP_BUFFER_MAX_RETRY           1
 150
 151 /*
 152  * Callback through which the result of a write request is reported by the
 153  * SCLP.
 154  */
 155 static void
 156 sclp_vt220_callback(struct sclp_req *request, void *data)
 157 {
 158         struct sclp_vt220_request *vt220_request;
 159         struct sclp_vt220_sccb *sccb;
 160
 161         vt220_request = (struct sclp_vt220_request *) data;
 162         if (request->status == SCLP_REQ_FAILED) {
 163                 sclp_vt220_process_queue(vt220_request);
 164                 return;
 165         }
 166         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
 167
 168         /* Check SCLP response code and choose suitable action  */
 169         switch (sccb->header.response_code) {
 170         case 0x0020 :
 171                 break;
 172
 173         case 0x05f0: /* Target resource in improper state */
 174                 break;
 175
 176         case 0x0340: /* Contained SCLP equipment check */
 177                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 178                         break;
 179                 /* Remove processed buffers and requeue rest */
 180                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 181                         /* Not all buffers were processed */
 182                         sccb->header.response_code = 0x0000;
 183                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 184                         if (sclp_add_request(request) == 0)
 185                                 return;
 186                 }
 187                 break;
 188
 189         case 0x0040: /* SCLP equipment check */
 190                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 191                         break;
 192                 sccb->header.response_code = 0x0000;
 193                 vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 194                 if (sclp_add_request(request) == 0)
 195                         return;
 196                 break;
 197
 198         default:
 199                 break;
 200         }
 201         sclp_vt220_process_queue(vt220_request);
 202 }
 203
 204 /*
 205  * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
 206  * otherwise.
 207  */
 208 static int
 209 __sclp_vt220_emit(struct sclp_vt220_request *request)
 210 {
 211         if (!(sclp_vt220_register.sclp_receive_mask & EVTYP_VT220MSG_MASK)) {
 212                 request->sclp_req.status = SCLP_REQ_FAILED;
 213                 return -EIO;
 214         }
 215         request->sclp_req.command = SCLP_CMDW_WRITE_EVENT_DATA;
 216         request->sclp_req.status = SCLP_REQ_FILLED;
 217         request->sclp_req.callback = sclp_vt220_callback;
 218         request->sclp_req.callback_data = (void *) request;
 219
 220         return sclp_add_request(&request->sclp_req);
 221 }
 222
 223 /*
 224  * Queue and emit current request.
 225  */
 226 static void
 227 sclp_vt220_emit_current(void)
 228 {
 229         unsigned long flags;
 230         struct sclp_vt220_request *request;
 231         struct sclp_vt220_sccb *sccb;
 232
 233         spin_lock_irqsave(&sclp_vt220_lock, flags);
 234         if (sclp_vt220_current_request) {
 235                 sccb = (struct sclp_vt220_sccb *)
 236                                 sclp_vt220_current_request->sclp_req.sccb;
 237                 /* Only emit buffers with content */
 238                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 239                         list_add_tail(&sclp_vt220_current_request->list,
 240                                       &sclp_vt220_outqueue);
 241                         sclp_vt220_current_request = NULL;
 242                         if (timer_pending(&sclp_vt220_timer))
 243                                 del_timer(&sclp_vt220_timer);
 244                 }
 245                 sclp_vt220_flush_later = 0;
 246         }
 247         if (sclp_vt220_queue_running || sclp_vt220_suspended)
 248                 goto out_unlock;
 249         if (list_empty(&sclp_vt220_outqueue))
 250                 goto out_unlock;
 251         request = list_first_entry(&sclp_vt220_outqueue,
 252                                    struct sclp_vt220_request, list);
 253         sclp_vt220_queue_running = 1;
 254         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 255
 256         if (__sclp_vt220_emit(request))
 257                 sclp_vt220_process_queue(request);
 258         return;
 259 out_unlock:
 260         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 261 }
 262
 263 #define SCLP_NORMAL_WRITE       0x00
 264
 265 /*
 266  * Helper function to initialize a page with the sclp request structure.
 267  */
 268 static struct sclp_vt220_request *
 269 sclp_vt220_initialize_page(void *page)
 270 {
 271         struct sclp_vt220_request *request;
 272         struct sclp_vt220_sccb *sccb;
 273
 274         /* Place request structure at end of page */
 275         request = ((struct sclp_vt220_request *)
 276                         ((addr_t) page + PAGE_SIZE)) - 1;
 277         request->retry_count = 0;
 278         request->sclp_req.sccb = page;
 279         /* SCCB goes at start of page */
 280         sccb = (struct sclp_vt220_sccb *) page;
 281         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
 282         sccb->header.length = sizeof(struct sclp_vt220_sccb);
 283         sccb->header.function_code = SCLP_NORMAL_WRITE;
 284         sccb->header.response_code = 0x0000;
 285         sccb->evbuf.type = EVTYP_VT220MSG;
 286         sccb->evbuf.length = sizeof(struct evbuf_header);
 287
 288         return request;
 289 }
 290
 291 static inline unsigned int
 292 sclp_vt220_space_left(struct sclp_vt220_request *request)
 293 {
 294         struct sclp_vt220_sccb *sccb;
 295         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 296         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
 297                sccb->header.length;
 298 }
 299
 300 static inline unsigned int
 301 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
 302 {
 303         struct sclp_vt220_sccb *sccb;
 304         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 305         return sccb->evbuf.length - sizeof(struct evbuf_header);
 306 }
 307
 308 /*
 309  * Add msg to buffer associated with request. Return the number of characters
 310  * added.
 311  */
 312 static int
 313 sclp_vt220_add_msg(struct sclp_vt220_request *request,
 314                    const unsigned char *msg, int count, int convertlf)
 315 {
 316         struct sclp_vt220_sccb *sccb;
 317         void *buffer;
 318         unsigned char c;
 319         int from;
 320         int to;
 321
 322         if (count > sclp_vt220_space_left(request))
 323                 count = sclp_vt220_space_left(request);
 324         if (count <= 0)
 325                 return 0;
 326
 327         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 328         buffer = (void *) ((addr_t) sccb + sccb->header.length);
 329
 330         if (convertlf) {
 331                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
 332                 for (from=0, to=0;
 333                      (from < count) && (to < sclp_vt220_space_left(request));
 334                      from++) {
 335                         /* Retrieve character */
 336                         c = msg[from];
 337                         /* Perform conversion */
 338                         if (c == 0x0a) {
 339                                 if (to + 1 < sclp_vt220_space_left(request)) {
 340                                         ((unsigned char *) buffer)[to++] = c;
 341                                         ((unsigned char *) buffer)[to++] = 0x0d;
 342                                 } else
 343                                         break;
 344
 345                         } else
 346                                 ((unsigned char *) buffer)[to++] = c;
 347                 }
 348                 sccb->header.length += to;
 349                 sccb->evbuf.length += to;
 350                 return from;
 351         } else {
 352                 memcpy(buffer, (const void *) msg, count);
 353                 sccb->header.length += count;
 354                 sccb->evbuf.length += count;
 355                 return count;
 356         }
 357 }
 358
 359 /*
 360  * Emit buffer after having waited long enough for more data to arrive.
 361  */
 362 static void
 363 sclp_vt220_timeout(unsigned long data)
 364 {
 365         sclp_vt220_emit_current();
 366 }
 367
 368 #define BUFFER_MAX_DELAY        HZ/20
 369
 370 /*
 371  * Internal implementation of the write function. Write COUNT bytes of data
 372  * from memory at BUF
 373  * to the SCLP interface. In case that the data does not fit into the current
 374  * write buffer, emit the current one and allocate a new one. If there are no
 375  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 376  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 377  * otherwise the user has to explicitly call the flush function.
 378  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 379  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 380  * of bytes written.
 381  */
 382 static int
 383 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 384                    int convertlf, int may_fail)
 385 {
 386         unsigned long flags;
 387         void *page;
 388         int written;
 389         int overall_written;
 390
 391         if (count <= 0)
 392                 return 0;
 393         overall_written = 0;
 394         spin_lock_irqsave(&sclp_vt220_lock, flags);
 395         do {
 396                 /* Create an sclp output buffer if none exists yet */
 397                 if (sclp_vt220_current_request == NULL) {
 398                         while (list_empty(&sclp_vt220_empty)) {
 399                                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 400                                 if (may_fail || sclp_vt220_suspended)
 401                                         goto out;
 402                                 else
 403                                         sclp_sync_wait();
 404                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 405                         }
 406                         page = (void *) sclp_vt220_empty.next;
 407                         list_del((struct list_head *) page);
 408                         sclp_vt220_current_request =
 409                                 sclp_vt220_initialize_page(page);
 410                 }
 411                 /* Try to write the string to the current request buffer */
 412                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 413                                              buf, count, convertlf);
 414                 overall_written += written;
 415                 if (written == count)
 416                         break;
 417                 /*
 418                  * Not all characters could be written to the current
 419                  * output buffer. Emit the buffer, create a new buffer
 420                  * and then output the rest of the string.
 421                  */
 422                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 423                 sclp_vt220_emit_current();
 424                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 425                 buf += written;
 426                 count -= written;
 427         } while (count > 0);
 428         /* Setup timer to output current console buffer after some time */
 429         if (sclp_vt220_current_request != NULL &&
 430             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 431                 sclp_vt220_timer.function = sclp_vt220_timeout;
 432                 sclp_vt220_timer.data = 0UL;
 433                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 434                 add_timer(&sclp_vt220_timer);
 435         }
 436         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 437 out:
 438         return overall_written;
 439 }
 440
 441 /*
 442  * This routine is called by the kernel to write a series of
 443  * characters to the tty device.  The characters may come from
 444  * user space or kernel space.  This routine will return the
 445  * number of characters actually accepted for writing.
 446  */
 447 static int
 448 sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
 449 {
 450         return __sclp_vt220_write(buf, count, 1, 0, 1);
 451 }
 452
 453 #define SCLP_VT220_SESSION_ENDED        0x01
 454 #define SCLP_VT220_SESSION_STARTED      0x80
 455 #define SCLP_VT220_SESSION_DATA         0x00
 456
 457 /*
 458  * Called by the SCLP to report incoming event buffers.
 459  */
 460 static void
 461 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 462 {
 463         char *buffer;
 464         unsigned int count;
 465
 466         /* Ignore input if device is not open */
 467         if (sclp_vt220_tty == NULL)
 468                 return;
 469
 470         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 471         count = evbuf->length - sizeof(struct evbuf_header);
 472
 473         switch (*buffer) {
 474         case SCLP_VT220_SESSION_ENDED:
 475         case SCLP_VT220_SESSION_STARTED:
 476                 break;
 477         case SCLP_VT220_SESSION_DATA:
 478                 /* Send input to line discipline */
 479                 buffer++;
 480                 count--;
 481                 tty_insert_flip_string(sclp_vt220_tty, buffer, count);
 482                 tty_flip_buffer_push(sclp_vt220_tty);
 483                 break;
 484         }
 485 }
 486
 487 /*
 488  * This routine is called when a particular tty device is opened.
 489  */
 490 static int
 491 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 492 {
 493         if (tty->count == 1) {
 494                 sclp_vt220_tty = tty;
 495                 tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
 496                 if (tty->driver_data == NULL)
 497                         return -ENOMEM;
 498                 tty->low_latency = 0;
 499                 if (!tty->winsize.ws_row && !tty->winsize.ws_col) {
 500                         tty->winsize.ws_row = 24;
 501                         tty->winsize.ws_col = 80;
 502                 }
 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 static int
 527 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 528 {
 529         return __sclp_vt220_write(&ch, 1, 0, 0, 1);
 530 }
 531
 532 /*
 533  * This routine is called by the kernel after it has written a
 534  * series of characters to the tty device using put_char().
 535  */
 536 static void
 537 sclp_vt220_flush_chars(struct tty_struct *tty)
 538 {
 539         if (!sclp_vt220_queue_running)
 540                 sclp_vt220_emit_current();
 541         else
 542                 sclp_vt220_flush_later = 1;
 543 }
 544
 545 /*
 546  * This routine returns the numbers of characters the tty driver
 547  * will accept for queuing to be written.  This number is subject
 548  * to change as output buffers get emptied, or if the output flow
 549  * control is acted.
 550  */
 551 static int
 552 sclp_vt220_write_room(struct tty_struct *tty)
 553 {
 554         unsigned long flags;
 555         struct list_head *l;
 556         int count;
 557
 558         spin_lock_irqsave(&sclp_vt220_lock, flags);
 559         count = 0;
 560         if (sclp_vt220_current_request != NULL)
 561                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 562         list_for_each(l, &sclp_vt220_empty)
 563                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 564         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 565         return count;
 566 }
 567
 568 /*
 569  * Return number of buffered chars.
 570  */
 571 static int
 572 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 573 {
 574         unsigned long flags;
 575         struct list_head *l;
 576         struct sclp_vt220_request *r;
 577         int count;
 578
 579         spin_lock_irqsave(&sclp_vt220_lock, flags);
 580         count = 0;
 581         if (sclp_vt220_current_request != NULL)
 582                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 583         list_for_each(l, &sclp_vt220_outqueue) {
 584                 r = list_entry(l, struct sclp_vt220_request, list);
 585                 count += sclp_vt220_chars_stored(r);
 586         }
 587         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 588         return count;
 589 }
 590
 591 /*
 592  * Pass on all buffers to the hardware. Return only when there are no more
 593  * buffers pending.
 594  */
 595 static void
 596 sclp_vt220_flush_buffer(struct tty_struct *tty)
 597 {
 598         sclp_vt220_emit_current();
 599 }
 600
 601 /* Release allocated pages. */
 602 static void __init __sclp_vt220_free_pages(void)
 603 {
 604         struct list_head *page, *p;
 605
 606         list_for_each_safe(page, p, &sclp_vt220_empty) {
 607                 list_del(page);
 608                 free_page((unsigned long) page);
 609         }
 610 }
 611
 612 /* Release memory and unregister from sclp core. Controlled by init counting -
 613  * only the last invoker will actually perform these actions. */
 614 static void __init __sclp_vt220_cleanup(void)
 615 {
 616         sclp_vt220_init_count--;
 617         if (sclp_vt220_init_count != 0)
 618                 return;
 619         sclp_unregister(&sclp_vt220_register);
 620         __sclp_vt220_free_pages();
 621 }
 622
 623 /* Allocate buffer pages and register with sclp core. Controlled by init
 624  * counting - only the first invoker will actually perform these actions. */
 625 static int __init __sclp_vt220_init(int num_pages)
 626 {
 627         void *page;
 628         int i;
 629         int rc;
 630
 631         sclp_vt220_init_count++;
 632         if (sclp_vt220_init_count != 1)
 633                 return 0;
 634         spin_lock_init(&sclp_vt220_lock);
 635         INIT_LIST_HEAD(&sclp_vt220_empty);
 636         INIT_LIST_HEAD(&sclp_vt220_outqueue);
 637         init_timer(&sclp_vt220_timer);
 638         sclp_vt220_current_request = NULL;
 639         sclp_vt220_buffered_chars = 0;
 640         sclp_vt220_tty = NULL;
 641         sclp_vt220_flush_later = 0;
 642
 643         /* Allocate pages for output buffering */
 644         rc = -ENOMEM;
 645         for (i = 0; i < num_pages; i++) {
 646                 page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 647                 if (!page)
 648                         goto out;
 649                 list_add_tail(page, &sclp_vt220_empty);
 650         }
 651         rc = sclp_register(&sclp_vt220_register);
 652 out:
 653         if (rc) {
 654                 __sclp_vt220_free_pages();
 655                 sclp_vt220_init_count--;
 656         }
 657         return rc;
 658 }
 659
 660 static const struct tty_operations sclp_vt220_ops = {
 661         .open = sclp_vt220_open,
 662         .close = sclp_vt220_close,
 663         .write = sclp_vt220_write,
 664         .put_char = sclp_vt220_put_char,
 665         .flush_chars = sclp_vt220_flush_chars,
 666         .write_room = sclp_vt220_write_room,
 667         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 668         .flush_buffer = sclp_vt220_flush_buffer,
 669 };
 670
 671 /*
 672  * Register driver with SCLP and Linux and initialize internal tty structures.
 673  */
 674 static int __init 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(MAX_KMEM_PAGES);
 685         if (rc)
 686                 goto out_driver;
 687
 688         driver->owner = THIS_MODULE;
 689         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 690         driver->name = SCLP_VT220_DEVICE_NAME;
 691         driver->major = SCLP_VT220_MAJOR;
 692         driver->minor_start = SCLP_VT220_MINOR;
 693         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 694         driver->subtype = SYSTEM_TYPE_TTY;
 695         driver->init_termios = tty_std_termios;
 696         driver->flags = TTY_DRIVER_REAL_RAW;
 697         tty_set_operations(driver, &sclp_vt220_ops);
 698
 699         rc = tty_register_driver(driver);
 700         if (rc)
 701                 goto out_init;
 702         sclp_vt220_driver = driver;
 703         return 0;
 704
 705 out_init:
 706         __sclp_vt220_cleanup();
 707 out_driver:
 708         put_tty_driver(driver);
 709         return rc;
 710 }
 711 __initcall(sclp_vt220_tty_init);
 712
 713 static void __sclp_vt220_flush_buffer(void)
 714 {
 715         unsigned long flags;
 716
 717         sclp_vt220_emit_current();
 718         spin_lock_irqsave(&sclp_vt220_lock, flags);
 719         if (timer_pending(&sclp_vt220_timer))
 720                 del_timer(&sclp_vt220_timer);
 721         while (sclp_vt220_queue_running) {
 722                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 723                 sclp_sync_wait();
 724                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 725         }
 726         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 727 }
 728
 729 /*
 730  * Resume console: If there are cached messages, emit them.
 731  */
 732 static void sclp_vt220_resume(void)
 733 {
 734         unsigned long flags;
 735
 736         spin_lock_irqsave(&sclp_vt220_lock, flags);
 737         sclp_vt220_suspended = 0;
 738         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 739         sclp_vt220_emit_current();
 740 }
 741
 742 /*
 743  * Suspend console: Set suspend flag and flush console
 744  */
 745 static void sclp_vt220_suspend(void)
 746 {
 747         unsigned long flags;
 748
 749         spin_lock_irqsave(&sclp_vt220_lock, flags);
 750         sclp_vt220_suspended = 1;
 751         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 752         __sclp_vt220_flush_buffer();
 753 }
 754
 755 static void sclp_vt220_pm_event_fn(struct sclp_register *reg,
 756                                    enum sclp_pm_event sclp_pm_event)
 757 {
 758         switch (sclp_pm_event) {
 759         case SCLP_PM_EVENT_FREEZE:
 760                 sclp_vt220_suspend();
 761                 break;
 762         case SCLP_PM_EVENT_RESTORE:
 763         case SCLP_PM_EVENT_THAW:
 764                 sclp_vt220_resume();
 765                 break;
 766         }
 767 }
 768
 769 #ifdef CONFIG_SCLP_VT220_CONSOLE
 770
 771 static void
 772 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 773 {
 774         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1, 0);
 775 }
 776
 777 static struct tty_driver *
 778 sclp_vt220_con_device(struct console *c, int *index)
 779 {
 780         *index = 0;
 781         return sclp_vt220_driver;
 782 }
 783
 784 static int
 785 sclp_vt220_notify(struct notifier_block *self,
 786                           unsigned long event, void *data)
 787 {
 788         __sclp_vt220_flush_buffer();
 789         return NOTIFY_OK;
 790 }
 791
 792 static struct notifier_block on_panic_nb = {
 793         .notifier_call = sclp_vt220_notify,
 794         .priority = 1,
 795 };
 796
 797 static struct notifier_block on_reboot_nb = {
 798         .notifier_call = sclp_vt220_notify,
 799         .priority = 1,
 800 };
 801
 802 /* Structure needed to register with printk */
 803 static struct console sclp_vt220_console =
 804 {
 805         .name = SCLP_VT220_CONSOLE_NAME,
 806         .write = sclp_vt220_con_write,
 807         .device = sclp_vt220_con_device,
 808         .flags = CON_PRINTBUFFER,
 809         .index = SCLP_VT220_CONSOLE_INDEX
 810 };
 811
 812 static int __init
 813 sclp_vt220_con_init(void)
 814 {
 815         int rc;
 816
 817         if (!CONSOLE_IS_SCLP)
 818                 return 0;
 819         rc = __sclp_vt220_init(MAX_CONSOLE_PAGES);
 820         if (rc)
 821                 return rc;
 822         /* Attach linux console */
 823         atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
 824         register_reboot_notifier(&on_reboot_nb);
 825         register_console(&sclp_vt220_console);
 826         return 0;
 827 }
 828
 829 console_initcall(sclp_vt220_con_init);
 830 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 831