drivers/s390/char/sclp_vt220.c

   1 /*
   2  *  drivers/s390/char/sclp_vt220.c
   3  *    SCLP VT220 terminal driver.
   4  *
   5  *  S390 version
   6  *    Copyright (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/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         struct timer_list retry_timer;
  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 void __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         struct sclp_vt220_request *next;
 120         void *page;
 121
 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         next = NULL;
 131         if (!list_empty(&sclp_vt220_outqueue))
 132                 next = list_entry(sclp_vt220_outqueue.next,
 133                                   struct sclp_vt220_request, list);
 134         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 135         if (next != NULL)
 136                 __sclp_vt220_emit(next);
 137         else if (sclp_vt220_flush_later)
 138                 sclp_vt220_emit_current();
 139         wake_up(&sclp_vt220_waitq);
 140         /* Check if the tty needs a wake up call */
 141         if (sclp_vt220_tty != NULL) {
 142                 tty_wakeup(sclp_vt220_tty);
 143         }
 144 }
 145
 146 /*
 147  * Retry sclp write request after waiting some time for an sclp equipment
 148  * check to pass.
 149  */
 150 static void
 151 sclp_vt220_retry(unsigned long data)
 152 {
 153         struct sclp_vt220_request *request;
 154         struct sclp_vt220_sccb *sccb;
 155
 156         request = (struct sclp_vt220_request *) data;
 157         request->sclp_req.status = SCLP_REQ_FILLED;
 158         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 159         sccb->header.response_code = 0x0000;
 160         sclp_add_request(&request->sclp_req);
 161 }
 162
 163 #define SCLP_BUFFER_MAX_RETRY           5
 164 #define SCLP_BUFFER_RETRY_INTERVAL      2
 165
 166 /*
 167  * Callback through which the result of a write request is reported by the
 168  * SCLP.
 169  */
 170 static void
 171 sclp_vt220_callback(struct sclp_req *request, void *data)
 172 {
 173         struct sclp_vt220_request *vt220_request;
 174         struct sclp_vt220_sccb *sccb;
 175
 176         vt220_request = (struct sclp_vt220_request *) data;
 177         if (request->status == SCLP_REQ_FAILED) {
 178                 sclp_vt220_process_queue(vt220_request);
 179                 return;
 180         }
 181         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
 182
 183         /* Check SCLP response code and choose suitable action  */
 184         switch (sccb->header.response_code) {
 185         case 0x0020 :
 186                 break;
 187
 188         case 0x05f0: /* Target resource in improper state */
 189                 break;
 190
 191         case 0x0340: /* Contained SCLP equipment check */
 192                 if (vt220_request->retry_count++ > SCLP_BUFFER_MAX_RETRY)
 193                         break;
 194                 /* Remove processed buffers and requeue rest */
 195                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 196                         /* Not all buffers were processed */
 197                         sccb->header.response_code = 0x0000;
 198                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 199                         sclp_add_request(request);
 200                         return;
 201                 }
 202                 break;
 203
 204         case 0x0040: /* SCLP equipment check */
 205                 if (vt220_request->retry_count++ > SCLP_BUFFER_MAX_RETRY)
 206                         break;
 207                 /* Wait some time, then retry request */
 208                 vt220_request->retry_timer.function = sclp_vt220_retry;
 209                 vt220_request->retry_timer.data =
 210                         (unsigned long) vt220_request;
 211                 vt220_request->retry_timer.expires =
 212                         jiffies + SCLP_BUFFER_RETRY_INTERVAL*HZ;
 213                 add_timer(&vt220_request->retry_timer);
 214                 return;
 215
 216         default:
 217                 break;
 218         }
 219         sclp_vt220_process_queue(vt220_request);
 220 }
 221
 222 /*
 223  * Emit vt220 request buffer to SCLP.
 224  */
 225 static void
 226 __sclp_vt220_emit(struct sclp_vt220_request *request)
 227 {
 228         if (!(sclp_vt220_register.sclp_send_mask & EvTyp_VT220Msg_Mask)) {
 229                 request->sclp_req.status = SCLP_REQ_FAILED;
 230                 sclp_vt220_callback(&request->sclp_req, (void *) request);
 231                 return;
 232         }
 233         request->sclp_req.command = SCLP_CMDW_WRITEDATA;
 234         request->sclp_req.status = SCLP_REQ_FILLED;
 235         request->sclp_req.callback = sclp_vt220_callback;
 236         request->sclp_req.callback_data = (void *) request;
 237
 238         sclp_add_request(&request->sclp_req);
 239 }
 240
 241 /*
 242  * Queue and emit given request.
 243  */
 244 static void
 245 sclp_vt220_emit(struct sclp_vt220_request *request)
 246 {
 247         unsigned long flags;
 248         int count;
 249
 250         spin_lock_irqsave(&sclp_vt220_lock, flags);
 251         list_add_tail(&request->list, &sclp_vt220_outqueue);
 252         count = sclp_vt220_outqueue_count++;
 253         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 254         /* Emit only the first buffer immediately - callback takes care of
 255          * the rest */
 256         if (count == 0)
 257                 __sclp_vt220_emit(request);
 258 }
 259
 260 /*
 261  * Queue and emit current request.
 262  */
 263 static void
 264 sclp_vt220_emit_current(void)
 265 {
 266         unsigned long flags;
 267         struct sclp_vt220_request *request;
 268         struct sclp_vt220_sccb *sccb;
 269
 270         spin_lock_irqsave(&sclp_vt220_lock, flags);
 271         request = NULL;
 272         if (sclp_vt220_current_request != NULL) {
 273                 sccb = (struct sclp_vt220_sccb *)
 274                                 sclp_vt220_current_request->sclp_req.sccb;
 275                 /* Only emit buffers with content */
 276                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 277                         request = sclp_vt220_current_request;
 278                         sclp_vt220_current_request = NULL;
 279                         if (timer_pending(&sclp_vt220_timer))
 280                                 del_timer(&sclp_vt220_timer);
 281                 }
 282                 sclp_vt220_flush_later = 0;
 283         }
 284         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 285         if (request != NULL)
 286                 sclp_vt220_emit(request);
 287 }
 288
 289 #define SCLP_NORMAL_WRITE       0x00
 290
 291 /*
 292  * Helper function to initialize a page with the sclp request structure.
 293  */
 294 static struct sclp_vt220_request *
 295 sclp_vt220_initialize_page(void *page)
 296 {
 297         struct sclp_vt220_request *request;
 298         struct sclp_vt220_sccb *sccb;
 299
 300         /* Place request structure at end of page */
 301         request = ((struct sclp_vt220_request *)
 302                         ((addr_t) page + PAGE_SIZE)) - 1;
 303         init_timer(&request->retry_timer);
 304         request->retry_count = 0;
 305         request->sclp_req.sccb = page;
 306         /* SCCB goes at start of page */
 307         sccb = (struct sclp_vt220_sccb *) page;
 308         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
 309         sccb->header.length = sizeof(struct sclp_vt220_sccb);
 310         sccb->header.function_code = SCLP_NORMAL_WRITE;
 311         sccb->header.response_code = 0x0000;
 312         sccb->evbuf.type = EvTyp_VT220Msg;
 313         sccb->evbuf.length = sizeof(struct evbuf_header);
 314
 315         return request;
 316 }
 317
 318 static inline unsigned int
 319 sclp_vt220_space_left(struct sclp_vt220_request *request)
 320 {
 321         struct sclp_vt220_sccb *sccb;
 322         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 323         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
 324                sccb->header.length;
 325 }
 326
 327 static inline unsigned int
 328 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
 329 {
 330         struct sclp_vt220_sccb *sccb;
 331         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 332         return sccb->evbuf.length - sizeof(struct evbuf_header);
 333 }
 334
 335 /*
 336  * Add msg to buffer associated with request. Return the number of characters
 337  * added.
 338  */
 339 static int
 340 sclp_vt220_add_msg(struct sclp_vt220_request *request,
 341                    const unsigned char *msg, int count, int convertlf)
 342 {
 343         struct sclp_vt220_sccb *sccb;
 344         void *buffer;
 345         unsigned char c;
 346         int from;
 347         int to;
 348
 349         if (count > sclp_vt220_space_left(request))
 350                 count = sclp_vt220_space_left(request);
 351         if (count <= 0)
 352                 return 0;
 353
 354         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 355         buffer = (void *) ((addr_t) sccb + sccb->header.length);
 356
 357         if (convertlf) {
 358                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
 359                 for (from=0, to=0;
 360                      (from < count) && (to < sclp_vt220_space_left(request));
 361                      from++) {
 362                         /* Retrieve character */
 363                         c = msg[from];
 364                         /* Perform conversion */
 365                         if (c == 0x0a) {
 366                                 if (to + 1 < sclp_vt220_space_left(request)) {
 367                                         ((unsigned char *) buffer)[to++] = c;
 368                                         ((unsigned char *) buffer)[to++] = 0x0d;
 369                                 } else
 370                                         break;
 371
 372                         } else
 373                                 ((unsigned char *) buffer)[to++] = c;
 374                 }
 375                 sccb->header.length += to;
 376                 sccb->evbuf.length += to;
 377                 return from;
 378         } else {
 379                 memcpy(buffer, (const void *) msg, count);
 380                 sccb->header.length += count;
 381                 sccb->evbuf.length += count;
 382                 return count;
 383         }
 384 }
 385
 386 /*
 387  * Emit buffer after having waited long enough for more data to arrive.
 388  */
 389 static void
 390 sclp_vt220_timeout(unsigned long data)
 391 {
 392         sclp_vt220_emit_current();
 393 }
 394
 395 #define BUFFER_MAX_DELAY        HZ/2
 396
 397 /*
 398  * Internal implementation of the write function. Write COUNT bytes of data
 399  * from memory at BUF
 400  * to the SCLP interface. In case that the data does not fit into the current
 401  * write buffer, emit the current one and allocate a new one. If there are no
 402  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 403  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 404  * otherwise the user has to explicitly call the flush function.
 405  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 406  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 407  * of bytes written.
 408  */
 409 static int
 410 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 411                    int convertlf)
 412 {
 413         unsigned long flags;
 414         void *page;
 415         int written;
 416         int overall_written;
 417
 418         if (count <= 0)
 419                 return 0;
 420         overall_written = 0;
 421         spin_lock_irqsave(&sclp_vt220_lock, flags);
 422         do {
 423                 /* Create a sclp output buffer if none exists yet */
 424                 if (sclp_vt220_current_request == NULL) {
 425                         while (list_empty(&sclp_vt220_empty)) {
 426                                 spin_unlock_irqrestore(&sclp_vt220_lock,
 427                                                        flags);
 428                                 if (in_interrupt())
 429                                         sclp_sync_wait();
 430                                 else
 431                                         wait_event(sclp_vt220_waitq,
 432                                                 !list_empty(&sclp_vt220_empty));
 433                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 434                         }
 435                         page = (void *) sclp_vt220_empty.next;
 436                         list_del((struct list_head *) page);
 437                         sclp_vt220_current_request =
 438                                 sclp_vt220_initialize_page(page);
 439                 }
 440                 /* Try to write the string to the current request buffer */
 441                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 442                                              buf, count, convertlf);
 443                 overall_written += written;
 444                 if (written == count)
 445                         break;
 446                 /*
 447                  * Not all characters could be written to the current
 448                  * output buffer. Emit the buffer, create a new buffer
 449                  * and then output the rest of the string.
 450                  */
 451                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 452                 sclp_vt220_emit_current();
 453                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 454                 buf += written;
 455                 count -= written;
 456         } while (count > 0);
 457         /* Setup timer to output current console buffer after some time */
 458         if (sclp_vt220_current_request != NULL &&
 459             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 460                 sclp_vt220_timer.function = sclp_vt220_timeout;
 461                 sclp_vt220_timer.data = 0UL;
 462                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 463                 add_timer(&sclp_vt220_timer);
 464         }
 465         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 466         return overall_written;
 467 }
 468
 469 /*
 470  * This routine is called by the kernel to write a series of
 471  * characters to the tty device.  The characters may come from
 472  * user space or kernel space.  This routine will return the
 473  * number of characters actually accepted for writing.
 474  */
 475 static int
 476 sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
 477 {
 478         return __sclp_vt220_write(buf, count, 1, 0);
 479 }
 480
 481 #define SCLP_VT220_SESSION_ENDED        0x01
 482 #define SCLP_VT220_SESSION_STARTED      0x80
 483 #define SCLP_VT220_SESSION_DATA         0x00
 484
 485 /*
 486  * Called by the SCLP to report incoming event buffers.
 487  */
 488 static void
 489 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 490 {
 491         char *buffer;
 492         unsigned int count;
 493
 494         /* Ignore input if device is not open */
 495         if (sclp_vt220_tty == NULL)
 496                 return;
 497
 498         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 499         count = evbuf->length - sizeof(struct evbuf_header);
 500
 501         switch (*buffer) {
 502         case SCLP_VT220_SESSION_ENDED:
 503         case SCLP_VT220_SESSION_STARTED:
 504                 break;
 505         case SCLP_VT220_SESSION_DATA:
 506                 /* Send input to line discipline */
 507                 buffer++;
 508                 count--;
 509                 /* Prevent buffer overrun by discarding input. Note that
 510                  * because buffer_push works asynchronously, we cannot wait
 511                  * for the buffer to be emptied. */
 512                 if (count + sclp_vt220_tty->flip.count > TTY_FLIPBUF_SIZE)
 513                         count = TTY_FLIPBUF_SIZE - sclp_vt220_tty->flip.count;
 514                 memcpy(sclp_vt220_tty->flip.char_buf_ptr, buffer, count);
 515                 memset(sclp_vt220_tty->flip.flag_buf_ptr, TTY_NORMAL, count);
 516                 sclp_vt220_tty->flip.char_buf_ptr += count;
 517                 sclp_vt220_tty->flip.flag_buf_ptr += count;
 518                 sclp_vt220_tty->flip.count += count;
 519                 tty_flip_buffer_push(sclp_vt220_tty);
 520                 break;
 521         }
 522 }
 523
 524 /*
 525  * This routine is called when a particular tty device is opened.
 526  */
 527 static int
 528 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 529 {
 530         if (tty->count == 1) {
 531                 sclp_vt220_tty = tty;
 532                 tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
 533                 if (tty->driver_data == NULL)
 534                         return -ENOMEM;
 535                 tty->low_latency = 0;
 536         }
 537         return 0;
 538 }
 539
 540 /*
 541  * This routine is called when a particular tty device is closed.
 542  */
 543 static void
 544 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 545 {
 546         if (tty->count == 1) {
 547                 sclp_vt220_tty = NULL;
 548                 kfree(tty->driver_data);
 549                 tty->driver_data = NULL;
 550         }
 551 }
 552
 553 /*
 554  * This routine is called by the kernel to write a single
 555  * character to the tty device.  If the kernel uses this routine,
 556  * it must call the flush_chars() routine (if defined) when it is
 557  * done stuffing characters into the driver.
 558  *
 559  * NOTE: include/linux/tty_driver.h specifies that a character should be
 560  * ignored if there is no room in the queue. This driver implements a different
 561  * semantic in that it will block when there is no more room left.
 562  */
 563 static void
 564 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 565 {
 566         __sclp_vt220_write(&ch, 1, 0, 0);
 567 }
 568
 569 /*
 570  * This routine is called by the kernel after it has written a
 571  * series of characters to the tty device using put_char().
 572  */
 573 static void
 574 sclp_vt220_flush_chars(struct tty_struct *tty)
 575 {
 576         if (sclp_vt220_outqueue_count == 0)
 577                 sclp_vt220_emit_current();
 578         else
 579                 sclp_vt220_flush_later = 1;
 580 }
 581
 582 /*
 583  * This routine returns the numbers of characters the tty driver
 584  * will accept for queuing to be written.  This number is subject
 585  * to change as output buffers get emptied, or if the output flow
 586  * control is acted.
 587  */
 588 static int
 589 sclp_vt220_write_room(struct tty_struct *tty)
 590 {
 591         unsigned long flags;
 592         struct list_head *l;
 593         int count;
 594
 595         spin_lock_irqsave(&sclp_vt220_lock, flags);
 596         count = 0;
 597         if (sclp_vt220_current_request != NULL)
 598                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 599         list_for_each(l, &sclp_vt220_empty)
 600                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 601         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 602         return count;
 603 }
 604
 605 /*
 606  * Return number of buffered chars.
 607  */
 608 static int
 609 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 610 {
 611         unsigned long flags;
 612         struct list_head *l;
 613         struct sclp_vt220_request *r;
 614         int count;
 615
 616         spin_lock_irqsave(&sclp_vt220_lock, flags);
 617         count = 0;
 618         if (sclp_vt220_current_request != NULL)
 619                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 620         list_for_each(l, &sclp_vt220_outqueue) {
 621                 r = list_entry(l, struct sclp_vt220_request, list);
 622                 count += sclp_vt220_chars_stored(r);
 623         }
 624         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 625         return count;
 626 }
 627
 628 static void
 629 __sclp_vt220_flush_buffer(void)
 630 {
 631         unsigned long flags;
 632
 633         sclp_vt220_emit_current();
 634         spin_lock_irqsave(&sclp_vt220_lock, flags);
 635         if (timer_pending(&sclp_vt220_timer))
 636                 del_timer(&sclp_vt220_timer);
 637         while (sclp_vt220_outqueue_count > 0) {
 638                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 639                 sclp_sync_wait();
 640                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 641         }
 642         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 643 }
 644
 645 /*
 646  * Pass on all buffers to the hardware. Return only when there are no more
 647  * buffers pending.
 648  */
 649 static void
 650 sclp_vt220_flush_buffer(struct tty_struct *tty)
 651 {
 652         sclp_vt220_emit_current();
 653 }
 654
 655 /*
 656  * Initialize all relevant components and register driver with system.
 657  */
 658 static int
 659 __sclp_vt220_init(int early)
 660 {
 661         void *page;
 662         int i;
 663
 664         if (sclp_vt220_initialized)
 665                 return 0;
 666         sclp_vt220_initialized = 1;
 667         spin_lock_init(&sclp_vt220_lock);
 668         INIT_LIST_HEAD(&sclp_vt220_empty);
 669         INIT_LIST_HEAD(&sclp_vt220_outqueue);
 670         init_waitqueue_head(&sclp_vt220_waitq);
 671         init_timer(&sclp_vt220_timer);
 672         sclp_vt220_current_request = NULL;
 673         sclp_vt220_buffered_chars = 0;
 674         sclp_vt220_outqueue_count = 0;
 675         sclp_vt220_tty = NULL;
 676         sclp_vt220_flush_later = 0;
 677
 678         /* Allocate pages for output buffering */
 679         for (i = 0; i < (early ? MAX_CONSOLE_PAGES : MAX_KMEM_PAGES); i++) {
 680                 if (early)
 681                         page = alloc_bootmem_low_pages(PAGE_SIZE);
 682                 else
 683                         page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 684                 if (!page)
 685                         return -ENOMEM;
 686                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 687         }
 688         return 0;
 689 }
 690
 691 static struct tty_operations sclp_vt220_ops = {
 692         .open = sclp_vt220_open,
 693         .close = sclp_vt220_close,
 694         .write = sclp_vt220_write,
 695         .put_char = sclp_vt220_put_char,
 696         .flush_chars = sclp_vt220_flush_chars,
 697         .write_room = sclp_vt220_write_room,
 698         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 699         .flush_buffer = sclp_vt220_flush_buffer
 700 };
 701
 702 /*
 703  * Register driver with SCLP and Linux and initialize internal tty structures.
 704  */
 705 int __init
 706 sclp_vt220_tty_init(void)
 707 {
 708         struct tty_driver *driver;
 709         int rc;
 710
 711         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 712          * symmetry between VM and LPAR systems regarding ttyS1. */
 713         driver = alloc_tty_driver(1);
 714         if (!driver)
 715                 return -ENOMEM;
 716         rc = __sclp_vt220_init(0);
 717         if (rc) {
 718                 put_tty_driver(driver);
 719                 return rc;
 720         }
 721         rc = sclp_register(&sclp_vt220_register);
 722         if (rc) {
 723                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 724                        "could not register tty - "
 725                        "sclp_register returned %d\n", rc);
 726                 put_tty_driver(driver);
 727                 return rc;
 728         }
 729
 730         driver->owner = THIS_MODULE;
 731         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 732         driver->name = SCLP_VT220_DEVICE_NAME;
 733         driver->major = SCLP_VT220_MAJOR;
 734         driver->minor_start = SCLP_VT220_MINOR;
 735         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 736         driver->subtype = SYSTEM_TYPE_TTY;
 737         driver->init_termios = tty_std_termios;
 738         driver->flags = TTY_DRIVER_REAL_RAW;
 739         tty_set_operations(driver, &sclp_vt220_ops);
 740
 741         rc = tty_register_driver(driver);
 742         if (rc) {
 743                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 744                        "could not register tty - "
 745                        "tty_register_driver returned %d\n", rc);
 746                 put_tty_driver(driver);
 747                 return rc;
 748         }
 749         sclp_vt220_driver = driver;
 750         return 0;
 751 }
 752
 753 module_init(sclp_vt220_tty_init);
 754
 755 #ifdef CONFIG_SCLP_VT220_CONSOLE
 756
 757 static void
 758 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 759 {
 760         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1);
 761 }
 762
 763 static struct tty_driver *
 764 sclp_vt220_con_device(struct console *c, int *index)
 765 {
 766         *index = 0;
 767         return sclp_vt220_driver;
 768 }
 769
 770 /*
 771  * This routine is called from panic when the kernel is going to give up.
 772  * We have to make sure that all buffers will be flushed to the SCLP.
 773  * Note that this function may be called from within an interrupt context.
 774  */
 775 static void
 776 sclp_vt220_con_unblank(void)
 777 {
 778         __sclp_vt220_flush_buffer();
 779 }
 780
 781 /* Structure needed to register with printk */
 782 static struct console sclp_vt220_console =
 783 {
 784         .name = SCLP_VT220_CONSOLE_NAME,
 785         .write = sclp_vt220_con_write,
 786         .device = sclp_vt220_con_device,
 787         .unblank = sclp_vt220_con_unblank,
 788         .flags = CON_PRINTBUFFER,
 789         .index = SCLP_VT220_CONSOLE_INDEX
 790 };
 791
 792 static int __init
 793 sclp_vt220_con_init(void)
 794 {
 795         int rc;
 796
 797         if (!CONSOLE_IS_SCLP)
 798                 return 0;
 799         rc = __sclp_vt220_init(1);
 800         if (rc)
 801                 return rc;
 802         /* Attach linux console */
 803         register_console(&sclp_vt220_console);
 804         return 0;
 805 }
 806
 807 console_initcall(sclp_vt220_con_init);
 808 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 809