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                 if ((sclp_vt220_tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
 143                     (sclp_vt220_tty->ldisc.write_wakeup != NULL))
 144                         (sclp_vt220_tty->ldisc.write_wakeup)(sclp_vt220_tty);
 145                 wake_up_interruptible(&sclp_vt220_tty->write_wait);
 146         }
 147 }
 148
 149 /*
 150  * Retry sclp write request after waiting some time for an sclp equipment
 151  * check to pass.
 152  */
 153 static void
 154 sclp_vt220_retry(unsigned long data)
 155 {
 156         struct sclp_vt220_request *request;
 157         struct sclp_vt220_sccb *sccb;
 158
 159         request = (struct sclp_vt220_request *) data;
 160         request->sclp_req.status = SCLP_REQ_FILLED;
 161         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 162         sccb->header.response_code = 0x0000;
 163         sclp_add_request(&request->sclp_req);
 164 }
 165
 166 #define SCLP_BUFFER_MAX_RETRY           5
 167 #define SCLP_BUFFER_RETRY_INTERVAL      2
 168
 169 /*
 170  * Callback through which the result of a write request is reported by the
 171  * SCLP.
 172  */
 173 static void
 174 sclp_vt220_callback(struct sclp_req *request, void *data)
 175 {
 176         struct sclp_vt220_request *vt220_request;
 177         struct sclp_vt220_sccb *sccb;
 178
 179         vt220_request = (struct sclp_vt220_request *) data;
 180         if (request->status == SCLP_REQ_FAILED) {
 181                 sclp_vt220_process_queue(vt220_request);
 182                 return;
 183         }
 184         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
 185
 186         /* Check SCLP response code and choose suitable action  */
 187         switch (sccb->header.response_code) {
 188         case 0x0020 :
 189                 break;
 190
 191         case 0x05f0: /* Target resource in improper state */
 192                 break;
 193
 194         case 0x0340: /* Contained SCLP equipment check */
 195                 if (vt220_request->retry_count++ > SCLP_BUFFER_MAX_RETRY)
 196                         break;
 197                 /* Remove processed buffers and requeue rest */
 198                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 199                         /* Not all buffers were processed */
 200                         sccb->header.response_code = 0x0000;
 201                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 202                         sclp_add_request(request);
 203                         return;
 204                 }
 205                 break;
 206
 207         case 0x0040: /* SCLP equipment check */
 208                 if (vt220_request->retry_count++ > SCLP_BUFFER_MAX_RETRY)
 209                         break;
 210                 /* Wait some time, then retry request */
 211                 vt220_request->retry_timer.function = sclp_vt220_retry;
 212                 vt220_request->retry_timer.data =
 213                         (unsigned long) vt220_request;
 214                 vt220_request->retry_timer.expires =
 215                         jiffies + SCLP_BUFFER_RETRY_INTERVAL*HZ;
 216                 add_timer(&vt220_request->retry_timer);
 217                 return;
 218
 219         default:
 220                 break;
 221         }
 222         sclp_vt220_process_queue(vt220_request);
 223 }
 224
 225 /*
 226  * Emit vt220 request buffer to SCLP.
 227  */
 228 static void
 229 __sclp_vt220_emit(struct sclp_vt220_request *request)
 230 {
 231         if (!(sclp_vt220_register.sclp_send_mask & EvTyp_VT220Msg_Mask)) {
 232                 request->sclp_req.status = SCLP_REQ_FAILED;
 233                 sclp_vt220_callback(&request->sclp_req, (void *) request);
 234                 return;
 235         }
 236         request->sclp_req.command = SCLP_CMDW_WRITEDATA;
 237         request->sclp_req.status = SCLP_REQ_FILLED;
 238         request->sclp_req.callback = sclp_vt220_callback;
 239         request->sclp_req.callback_data = (void *) request;
 240
 241         sclp_add_request(&request->sclp_req);
 242 }
 243
 244 /*
 245  * Queue and emit given request.
 246  */
 247 static void
 248 sclp_vt220_emit(struct sclp_vt220_request *request)
 249 {
 250         unsigned long flags;
 251         int count;
 252
 253         spin_lock_irqsave(&sclp_vt220_lock, flags);
 254         list_add_tail(&request->list, &sclp_vt220_outqueue);
 255         count = sclp_vt220_outqueue_count++;
 256         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 257         /* Emit only the first buffer immediately - callback takes care of
 258          * the rest */
 259         if (count == 0)
 260                 __sclp_vt220_emit(request);
 261 }
 262
 263 /*
 264  * Queue and emit current request.
 265  */
 266 static void
 267 sclp_vt220_emit_current(void)
 268 {
 269         unsigned long flags;
 270         struct sclp_vt220_request *request;
 271         struct sclp_vt220_sccb *sccb;
 272
 273         spin_lock_irqsave(&sclp_vt220_lock, flags);
 274         request = NULL;
 275         if (sclp_vt220_current_request != NULL) {
 276                 sccb = (struct sclp_vt220_sccb *)
 277                                 sclp_vt220_current_request->sclp_req.sccb;
 278                 /* Only emit buffers with content */
 279                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 280                         request = sclp_vt220_current_request;
 281                         sclp_vt220_current_request = NULL;
 282                         if (timer_pending(&sclp_vt220_timer))
 283                                 del_timer(&sclp_vt220_timer);
 284                 }
 285                 sclp_vt220_flush_later = 0;
 286         }
 287         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 288         if (request != NULL)
 289                 sclp_vt220_emit(request);
 290 }
 291
 292 #define SCLP_NORMAL_WRITE       0x00
 293
 294 /*
 295  * Helper function to initialize a page with the sclp request structure.
 296  */
 297 static struct sclp_vt220_request *
 298 sclp_vt220_initialize_page(void *page)
 299 {
 300         struct sclp_vt220_request *request;
 301         struct sclp_vt220_sccb *sccb;
 302
 303         /* Place request structure at end of page */
 304         request = ((struct sclp_vt220_request *)
 305                         ((addr_t) page + PAGE_SIZE)) - 1;
 306         init_timer(&request->retry_timer);
 307         request->retry_count = 0;
 308         request->sclp_req.sccb = page;
 309         /* SCCB goes at start of page */
 310         sccb = (struct sclp_vt220_sccb *) page;
 311         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
 312         sccb->header.length = sizeof(struct sclp_vt220_sccb);
 313         sccb->header.function_code = SCLP_NORMAL_WRITE;
 314         sccb->header.response_code = 0x0000;
 315         sccb->evbuf.type = EvTyp_VT220Msg;
 316         sccb->evbuf.length = sizeof(struct evbuf_header);
 317
 318         return request;
 319 }
 320
 321 static inline unsigned int
 322 sclp_vt220_space_left(struct sclp_vt220_request *request)
 323 {
 324         struct sclp_vt220_sccb *sccb;
 325         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 326         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
 327                sccb->header.length;
 328 }
 329
 330 static inline unsigned int
 331 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
 332 {
 333         struct sclp_vt220_sccb *sccb;
 334         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 335         return sccb->evbuf.length - sizeof(struct evbuf_header);
 336 }
 337
 338 /*
 339  * Add msg to buffer associated with request. Return the number of characters
 340  * added.
 341  */
 342 static int
 343 sclp_vt220_add_msg(struct sclp_vt220_request *request,
 344                    const unsigned char *msg, int count, int convertlf)
 345 {
 346         struct sclp_vt220_sccb *sccb;
 347         void *buffer;
 348         unsigned char c;
 349         int from;
 350         int to;
 351
 352         if (count > sclp_vt220_space_left(request))
 353                 count = sclp_vt220_space_left(request);
 354         if (count <= 0)
 355                 return 0;
 356
 357         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 358         buffer = (void *) ((addr_t) sccb + sccb->header.length);
 359
 360         if (convertlf) {
 361                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
 362                 for (from=0, to=0;
 363                      (from < count) && (to < sclp_vt220_space_left(request));
 364                      from++) {
 365                         /* Retrieve character */
 366                         c = msg[from];
 367                         /* Perform conversion */
 368                         if (c == 0x0a) {
 369                                 if (to + 1 < sclp_vt220_space_left(request)) {
 370                                         ((unsigned char *) buffer)[to++] = c;
 371                                         ((unsigned char *) buffer)[to++] = 0x0d;
 372                                 } else
 373                                         break;
 374
 375                         } else
 376                                 ((unsigned char *) buffer)[to++] = c;
 377                 }
 378                 sccb->header.length += to;
 379                 sccb->evbuf.length += to;
 380                 return from;
 381         } else {
 382                 memcpy(buffer, (const void *) msg, count);
 383                 sccb->header.length += count;
 384                 sccb->evbuf.length += count;
 385                 return count;
 386         }
 387 }
 388
 389 /*
 390  * Emit buffer after having waited long enough for more data to arrive.
 391  */
 392 static void
 393 sclp_vt220_timeout(unsigned long data)
 394 {
 395         sclp_vt220_emit_current();
 396 }
 397
 398 #define BUFFER_MAX_DELAY        HZ/2
 399
 400 /*
 401  * Internal implementation of the write function. Write COUNT bytes of data
 402  * from memory at BUF
 403  * to the SCLP interface. In case that the data does not fit into the current
 404  * write buffer, emit the current one and allocate a new one. If there are no
 405  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 406  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 407  * otherwise the user has to explicitly call the flush function.
 408  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 409  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 410  * of bytes written.
 411  */
 412 static int
 413 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 414                    int convertlf)
 415 {
 416         unsigned long flags;
 417         void *page;
 418         int written;
 419         int overall_written;
 420
 421         if (count <= 0)
 422                 return 0;
 423         overall_written = 0;
 424         spin_lock_irqsave(&sclp_vt220_lock, flags);
 425         do {
 426                 /* Create a sclp output buffer if none exists yet */
 427                 if (sclp_vt220_current_request == NULL) {
 428                         while (list_empty(&sclp_vt220_empty)) {
 429                                 spin_unlock_irqrestore(&sclp_vt220_lock,
 430                                                        flags);
 431                                 if (in_interrupt())
 432                                         sclp_sync_wait();
 433                                 else
 434                                         wait_event(sclp_vt220_waitq,
 435                                                 !list_empty(&sclp_vt220_empty));
 436                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 437                         }
 438                         page = (void *) sclp_vt220_empty.next;
 439                         list_del((struct list_head *) page);
 440                         sclp_vt220_current_request =
 441                                 sclp_vt220_initialize_page(page);
 442                 }
 443                 /* Try to write the string to the current request buffer */
 444                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 445                                              buf, count, convertlf);
 446                 overall_written += written;
 447                 if (written == count)
 448                         break;
 449                 /*
 450                  * Not all characters could be written to the current
 451                  * output buffer. Emit the buffer, create a new buffer
 452                  * and then output the rest of the string.
 453                  */
 454                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 455                 sclp_vt220_emit_current();
 456                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 457                 buf += written;
 458                 count -= written;
 459         } while (count > 0);
 460         /* Setup timer to output current console buffer after some time */
 461         if (sclp_vt220_current_request != NULL &&
 462             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 463                 sclp_vt220_timer.function = sclp_vt220_timeout;
 464                 sclp_vt220_timer.data = 0UL;
 465                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 466                 add_timer(&sclp_vt220_timer);
 467         }
 468         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 469         return overall_written;
 470 }
 471
 472 /*
 473  * This routine is called by the kernel to write a series of
 474  * characters to the tty device.  The characters may come from
 475  * user space or kernel space.  This routine will return the
 476  * number of characters actually accepted for writing.
 477  */
 478 static int
 479 sclp_vt220_write(struct tty_struct *tty, int from_user,
 480                  const unsigned char *buf, int count)
 481 {
 482         int length;
 483         int ret;
 484
 485         if (!from_user)
 486                 return __sclp_vt220_write(buf, count, 1, 0);
 487         /* Use intermediate buffer to prevent calling copy_from_user() while
 488          * holding a lock. */
 489         ret = 0;
 490         while (count > 0) {
 491                 length = count < SCLP_VT220_BUF_SIZE ?
 492                          count : SCLP_VT220_BUF_SIZE;
 493                 length -= copy_from_user(tty->driver_data,
 494                                 (const unsigned char __user *)buf, length);
 495                 if (length == 0) {
 496                         if (!ret)
 497                                 return -EFAULT;
 498                         break;
 499                 }
 500                 length = __sclp_vt220_write(tty->driver_data, length, 1, 0);
 501                 buf += length;
 502                 count -= length;
 503                 ret += length;
 504         }
 505         return ret;
 506 }
 507
 508 #define SCLP_VT220_SESSION_ENDED        0x01
 509 #define SCLP_VT220_SESSION_STARTED      0x80
 510 #define SCLP_VT220_SESSION_DATA         0x00
 511
 512 /*
 513  * Called by the SCLP to report incoming event buffers.
 514  */
 515 static void
 516 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 517 {
 518         char *buffer;
 519         unsigned int count;
 520
 521         /* Ignore input if device is not open */
 522         if (sclp_vt220_tty == NULL)
 523                 return;
 524
 525         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 526         count = evbuf->length - sizeof(struct evbuf_header);
 527
 528         switch (*buffer) {
 529         case SCLP_VT220_SESSION_ENDED:
 530         case SCLP_VT220_SESSION_STARTED:
 531                 break;
 532         case SCLP_VT220_SESSION_DATA:
 533                 /* Send input to line discipline */
 534                 buffer++;
 535                 count--;
 536                 /* Prevent buffer overrun by discarding input. Note that
 537                  * because buffer_push works asynchronously, we cannot wait
 538                  * for the buffer to be emptied. */
 539                 if (count + sclp_vt220_tty->flip.count > TTY_FLIPBUF_SIZE)
 540                         count = TTY_FLIPBUF_SIZE - sclp_vt220_tty->flip.count;
 541                 memcpy(sclp_vt220_tty->flip.char_buf_ptr, buffer, count);
 542                 memset(sclp_vt220_tty->flip.flag_buf_ptr, TTY_NORMAL, count);
 543                 sclp_vt220_tty->flip.char_buf_ptr += count;
 544                 sclp_vt220_tty->flip.flag_buf_ptr += count;
 545                 sclp_vt220_tty->flip.count += count;
 546                 tty_flip_buffer_push(sclp_vt220_tty);
 547                 break;
 548         }
 549 }
 550
 551 /*
 552  * This routine is called when a particular tty device is opened.
 553  */
 554 static int
 555 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 556 {
 557         if (tty->count == 1) {
 558                 sclp_vt220_tty = tty;
 559                 tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
 560                 if (tty->driver_data == NULL)
 561                         return -ENOMEM;
 562                 tty->low_latency = 0;
 563         }
 564         return 0;
 565 }
 566
 567 /*
 568  * This routine is called when a particular tty device is closed.
 569  */
 570 static void
 571 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 572 {
 573         if (tty->count == 1) {
 574                 sclp_vt220_tty = NULL;
 575                 kfree(tty->driver_data);
 576                 tty->driver_data = NULL;
 577         }
 578 }
 579
 580 /*
 581  * This routine is called by the kernel to write a single
 582  * character to the tty device.  If the kernel uses this routine,
 583  * it must call the flush_chars() routine (if defined) when it is
 584  * done stuffing characters into the driver.
 585  *
 586  * NOTE: include/linux/tty_driver.h specifies that a character should be
 587  * ignored if there is no room in the queue. This driver implements a different
 588  * semantic in that it will block when there is no more room left.
 589  */
 590 static void
 591 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 592 {
 593         __sclp_vt220_write(&ch, 1, 0, 0);
 594 }
 595
 596 /*
 597  * This routine is called by the kernel after it has written a
 598  * series of characters to the tty device using put_char().
 599  */
 600 static void
 601 sclp_vt220_flush_chars(struct tty_struct *tty)
 602 {
 603         if (sclp_vt220_outqueue_count == 0)
 604                 sclp_vt220_emit_current();
 605         else
 606                 sclp_vt220_flush_later = 1;
 607 }
 608
 609 /*
 610  * This routine returns the numbers of characters the tty driver
 611  * will accept for queuing to be written.  This number is subject
 612  * to change as output buffers get emptied, or if the output flow
 613  * control is acted.
 614  */
 615 static int
 616 sclp_vt220_write_room(struct tty_struct *tty)
 617 {
 618         unsigned long flags;
 619         struct list_head *l;
 620         int count;
 621
 622         spin_lock_irqsave(&sclp_vt220_lock, flags);
 623         count = 0;
 624         if (sclp_vt220_current_request != NULL)
 625                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 626         list_for_each(l, &sclp_vt220_empty)
 627                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 628         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 629         return count;
 630 }
 631
 632 /*
 633  * Return number of buffered chars.
 634  */
 635 static int
 636 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 637 {
 638         unsigned long flags;
 639         struct list_head *l;
 640         struct sclp_vt220_request *r;
 641         int count;
 642
 643         spin_lock_irqsave(&sclp_vt220_lock, flags);
 644         count = 0;
 645         if (sclp_vt220_current_request != NULL)
 646                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 647         list_for_each(l, &sclp_vt220_outqueue) {
 648                 r = list_entry(l, struct sclp_vt220_request, list);
 649                 count += sclp_vt220_chars_stored(r);
 650         }
 651         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 652         return count;
 653 }
 654
 655 static void
 656 __sclp_vt220_flush_buffer(void)
 657 {
 658         unsigned long flags;
 659
 660         sclp_vt220_emit_current();
 661         spin_lock_irqsave(&sclp_vt220_lock, flags);
 662         if (timer_pending(&sclp_vt220_timer))
 663                 del_timer(&sclp_vt220_timer);
 664         while (sclp_vt220_outqueue_count > 0) {
 665                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 666                 sclp_sync_wait();
 667                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 668         }
 669         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 670 }
 671
 672 /*
 673  * Pass on all buffers to the hardware. Return only when there are no more
 674  * buffers pending.
 675  */
 676 static void
 677 sclp_vt220_flush_buffer(struct tty_struct *tty)
 678 {
 679         sclp_vt220_emit_current();
 680 }
 681
 682 /*
 683  * Initialize all relevant components and register driver with system.
 684  */
 685 static int
 686 __sclp_vt220_init(int early)
 687 {
 688         void *page;
 689         int i;
 690
 691         if (sclp_vt220_initialized)
 692                 return 0;
 693         sclp_vt220_initialized = 1;
 694         spin_lock_init(&sclp_vt220_lock);
 695         INIT_LIST_HEAD(&sclp_vt220_empty);
 696         INIT_LIST_HEAD(&sclp_vt220_outqueue);
 697         init_waitqueue_head(&sclp_vt220_waitq);
 698         init_timer(&sclp_vt220_timer);
 699         sclp_vt220_current_request = NULL;
 700         sclp_vt220_buffered_chars = 0;
 701         sclp_vt220_outqueue_count = 0;
 702         sclp_vt220_tty = NULL;
 703         sclp_vt220_flush_later = 0;
 704
 705         /* Allocate pages for output buffering */
 706         for (i = 0; i < (early ? MAX_CONSOLE_PAGES : MAX_KMEM_PAGES); i++) {
 707                 if (early)
 708                         page = alloc_bootmem_low_pages(PAGE_SIZE);
 709                 else
 710                         page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 711                 if (!page)
 712                         return -ENOMEM;
 713                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 714         }
 715         return 0;
 716 }
 717
 718 static struct tty_operations sclp_vt220_ops = {
 719         .open = sclp_vt220_open,
 720         .close = sclp_vt220_close,
 721         .write = sclp_vt220_write,
 722         .put_char = sclp_vt220_put_char,
 723         .flush_chars = sclp_vt220_flush_chars,
 724         .write_room = sclp_vt220_write_room,
 725         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 726         .flush_buffer = sclp_vt220_flush_buffer
 727 };
 728
 729 /*
 730  * Register driver with SCLP and Linux and initialize internal tty structures.
 731  */
 732 int __init
 733 sclp_vt220_tty_init(void)
 734 {
 735         struct tty_driver *driver;
 736         int rc;
 737
 738         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 739          * symmetry between VM and LPAR systems regarding ttyS1. */
 740         driver = alloc_tty_driver(1);
 741         if (!driver)
 742                 return -ENOMEM;
 743         rc = __sclp_vt220_init(0);
 744         if (rc) {
 745                 put_tty_driver(driver);
 746                 return rc;
 747         }
 748         rc = sclp_register(&sclp_vt220_register);
 749         if (rc) {
 750                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 751                        "could not register tty - "
 752                        "sclp_register returned %d\n", rc);
 753                 put_tty_driver(driver);
 754                 return rc;
 755         }
 756
 757         driver->owner = THIS_MODULE;
 758         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 759         driver->name = SCLP_VT220_DEVICE_NAME;
 760         driver->major = SCLP_VT220_MAJOR;
 761         driver->minor_start = SCLP_VT220_MINOR;
 762         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 763         driver->subtype = SYSTEM_TYPE_TTY;
 764         driver->init_termios = tty_std_termios;
 765         driver->flags = TTY_DRIVER_REAL_RAW;
 766         tty_set_operations(driver, &sclp_vt220_ops);
 767
 768         rc = tty_register_driver(driver);
 769         if (rc) {
 770                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 771                        "could not register tty - "
 772                        "tty_register_driver returned %d\n", rc);
 773                 put_tty_driver(driver);
 774                 return rc;
 775         }
 776         sclp_vt220_driver = driver;
 777         return 0;
 778 }
 779
 780 module_init(sclp_vt220_tty_init);
 781
 782 #ifdef CONFIG_SCLP_VT220_CONSOLE
 783
 784 static void
 785 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 786 {
 787         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1);
 788 }
 789
 790 static struct tty_driver *
 791 sclp_vt220_con_device(struct console *c, int *index)
 792 {
 793         *index = 0;
 794         return sclp_vt220_driver;
 795 }
 796
 797 /*
 798  * This routine is called from panic when the kernel is going to give up.
 799  * We have to make sure that all buffers will be flushed to the SCLP.
 800  * Note that this function may be called from within an interrupt context.
 801  */
 802 static void
 803 sclp_vt220_con_unblank(void)
 804 {
 805         __sclp_vt220_flush_buffer();
 806 }
 807
 808 /* Structure needed to register with printk */
 809 static struct console sclp_vt220_console =
 810 {
 811         .name = SCLP_VT220_CONSOLE_NAME,
 812         .write = sclp_vt220_con_write,
 813         .device = sclp_vt220_con_device,
 814         .unblank = sclp_vt220_con_unblank,
 815         .flags = CON_PRINTBUFFER,
 816         .index = SCLP_VT220_CONSOLE_INDEX
 817 };
 818
 819 static int __init
 820 sclp_vt220_con_init(void)
 821 {
 822         int rc;
 823
 824         if (!CONSOLE_IS_SCLP)
 825                 return 0;
 826         rc = __sclp_vt220_init(1);
 827         if (rc)
 828                 return rc;
 829         /* Attach linux console */
 830         register_console(&sclp_vt220_console);
 831         return 0;
 832 }
 833
 834 console_initcall(sclp_vt220_con_init);
 835 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 836