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, int from_user,
 477                  const unsigned char *buf, int count)
 478 {
 479         int length;
 480         int ret;
 481
 482         if (!from_user)
 483                 return __sclp_vt220_write(buf, count, 1, 0);
 484         /* Use intermediate buffer to prevent calling copy_from_user() while
 485          * holding a lock. */
 486         ret = 0;
 487         while (count > 0) {
 488                 length = count < SCLP_VT220_BUF_SIZE ?
 489                          count : SCLP_VT220_BUF_SIZE;
 490                 length -= copy_from_user(tty->driver_data,
 491                                 (const unsigned char __user *)buf, length);
 492                 if (length == 0) {
 493                         if (!ret)
 494                                 return -EFAULT;
 495                         break;
 496                 }
 497                 length = __sclp_vt220_write(tty->driver_data, length, 1, 0);
 498                 buf += length;
 499                 count -= length;
 500                 ret += length;
 501         }
 502         return ret;
 503 }
 504
 505 #define SCLP_VT220_SESSION_ENDED        0x01
 506 #define SCLP_VT220_SESSION_STARTED      0x80
 507 #define SCLP_VT220_SESSION_DATA         0x00
 508
 509 /*
 510  * Called by the SCLP to report incoming event buffers.
 511  */
 512 static void
 513 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 514 {
 515         char *buffer;
 516         unsigned int count;
 517
 518         /* Ignore input if device is not open */
 519         if (sclp_vt220_tty == NULL)
 520                 return;
 521
 522         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 523         count = evbuf->length - sizeof(struct evbuf_header);
 524
 525         switch (*buffer) {
 526         case SCLP_VT220_SESSION_ENDED:
 527         case SCLP_VT220_SESSION_STARTED:
 528                 break;
 529         case SCLP_VT220_SESSION_DATA:
 530                 /* Send input to line discipline */
 531                 buffer++;
 532                 count--;
 533                 /* Prevent buffer overrun by discarding input. Note that
 534                  * because buffer_push works asynchronously, we cannot wait
 535                  * for the buffer to be emptied. */
 536                 if (count + sclp_vt220_tty->flip.count > TTY_FLIPBUF_SIZE)
 537                         count = TTY_FLIPBUF_SIZE - sclp_vt220_tty->flip.count;
 538                 memcpy(sclp_vt220_tty->flip.char_buf_ptr, buffer, count);
 539                 memset(sclp_vt220_tty->flip.flag_buf_ptr, TTY_NORMAL, count);
 540                 sclp_vt220_tty->flip.char_buf_ptr += count;
 541                 sclp_vt220_tty->flip.flag_buf_ptr += count;
 542                 sclp_vt220_tty->flip.count += count;
 543                 tty_flip_buffer_push(sclp_vt220_tty);
 544                 break;
 545         }
 546 }
 547
 548 /*
 549  * This routine is called when a particular tty device is opened.
 550  */
 551 static int
 552 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 553 {
 554         if (tty->count == 1) {
 555                 sclp_vt220_tty = tty;
 556                 tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
 557                 if (tty->driver_data == NULL)
 558                         return -ENOMEM;
 559                 tty->low_latency = 0;
 560         }
 561         return 0;
 562 }
 563
 564 /*
 565  * This routine is called when a particular tty device is closed.
 566  */
 567 static void
 568 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 569 {
 570         if (tty->count == 1) {
 571                 sclp_vt220_tty = NULL;
 572                 kfree(tty->driver_data);
 573                 tty->driver_data = NULL;
 574         }
 575 }
 576
 577 /*
 578  * This routine is called by the kernel to write a single
 579  * character to the tty device.  If the kernel uses this routine,
 580  * it must call the flush_chars() routine (if defined) when it is
 581  * done stuffing characters into the driver.
 582  *
 583  * NOTE: include/linux/tty_driver.h specifies that a character should be
 584  * ignored if there is no room in the queue. This driver implements a different
 585  * semantic in that it will block when there is no more room left.
 586  */
 587 static void
 588 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 589 {
 590         __sclp_vt220_write(&ch, 1, 0, 0);
 591 }
 592
 593 /*
 594  * This routine is called by the kernel after it has written a
 595  * series of characters to the tty device using put_char().
 596  */
 597 static void
 598 sclp_vt220_flush_chars(struct tty_struct *tty)
 599 {
 600         if (sclp_vt220_outqueue_count == 0)
 601                 sclp_vt220_emit_current();
 602         else
 603                 sclp_vt220_flush_later = 1;
 604 }
 605
 606 /*
 607  * This routine returns the numbers of characters the tty driver
 608  * will accept for queuing to be written.  This number is subject
 609  * to change as output buffers get emptied, or if the output flow
 610  * control is acted.
 611  */
 612 static int
 613 sclp_vt220_write_room(struct tty_struct *tty)
 614 {
 615         unsigned long flags;
 616         struct list_head *l;
 617         int count;
 618
 619         spin_lock_irqsave(&sclp_vt220_lock, flags);
 620         count = 0;
 621         if (sclp_vt220_current_request != NULL)
 622                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 623         list_for_each(l, &sclp_vt220_empty)
 624                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 625         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 626         return count;
 627 }
 628
 629 /*
 630  * Return number of buffered chars.
 631  */
 632 static int
 633 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 634 {
 635         unsigned long flags;
 636         struct list_head *l;
 637         struct sclp_vt220_request *r;
 638         int count;
 639
 640         spin_lock_irqsave(&sclp_vt220_lock, flags);
 641         count = 0;
 642         if (sclp_vt220_current_request != NULL)
 643                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 644         list_for_each(l, &sclp_vt220_outqueue) {
 645                 r = list_entry(l, struct sclp_vt220_request, list);
 646                 count += sclp_vt220_chars_stored(r);
 647         }
 648         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 649         return count;
 650 }
 651
 652 static void
 653 __sclp_vt220_flush_buffer(void)
 654 {
 655         unsigned long flags;
 656
 657         sclp_vt220_emit_current();
 658         spin_lock_irqsave(&sclp_vt220_lock, flags);
 659         if (timer_pending(&sclp_vt220_timer))
 660                 del_timer(&sclp_vt220_timer);
 661         while (sclp_vt220_outqueue_count > 0) {
 662                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 663                 sclp_sync_wait();
 664                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 665         }
 666         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 667 }
 668
 669 /*
 670  * Pass on all buffers to the hardware. Return only when there are no more
 671  * buffers pending.
 672  */
 673 static void
 674 sclp_vt220_flush_buffer(struct tty_struct *tty)
 675 {
 676         sclp_vt220_emit_current();
 677 }
 678
 679 /*
 680  * Initialize all relevant components and register driver with system.
 681  */
 682 static int
 683 __sclp_vt220_init(int early)
 684 {
 685         void *page;
 686         int i;
 687
 688         if (sclp_vt220_initialized)
 689                 return 0;
 690         sclp_vt220_initialized = 1;
 691         spin_lock_init(&sclp_vt220_lock);
 692         INIT_LIST_HEAD(&sclp_vt220_empty);
 693         INIT_LIST_HEAD(&sclp_vt220_outqueue);
 694         init_waitqueue_head(&sclp_vt220_waitq);
 695         init_timer(&sclp_vt220_timer);
 696         sclp_vt220_current_request = NULL;
 697         sclp_vt220_buffered_chars = 0;
 698         sclp_vt220_outqueue_count = 0;
 699         sclp_vt220_tty = NULL;
 700         sclp_vt220_flush_later = 0;
 701
 702         /* Allocate pages for output buffering */
 703         for (i = 0; i < (early ? MAX_CONSOLE_PAGES : MAX_KMEM_PAGES); i++) {
 704                 if (early)
 705                         page = alloc_bootmem_low_pages(PAGE_SIZE);
 706                 else
 707                         page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 708                 if (!page)
 709                         return -ENOMEM;
 710                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 711         }
 712         return 0;
 713 }
 714
 715 static struct tty_operations sclp_vt220_ops = {
 716         .open = sclp_vt220_open,
 717         .close = sclp_vt220_close,
 718         .write = sclp_vt220_write,
 719         .put_char = sclp_vt220_put_char,
 720         .flush_chars = sclp_vt220_flush_chars,
 721         .write_room = sclp_vt220_write_room,
 722         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 723         .flush_buffer = sclp_vt220_flush_buffer
 724 };
 725
 726 /*
 727  * Register driver with SCLP and Linux and initialize internal tty structures.
 728  */
 729 int __init
 730 sclp_vt220_tty_init(void)
 731 {
 732         struct tty_driver *driver;
 733         int rc;
 734
 735         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 736          * symmetry between VM and LPAR systems regarding ttyS1. */
 737         driver = alloc_tty_driver(1);
 738         if (!driver)
 739                 return -ENOMEM;
 740         rc = __sclp_vt220_init(0);
 741         if (rc) {
 742                 put_tty_driver(driver);
 743                 return rc;
 744         }
 745         rc = sclp_register(&sclp_vt220_register);
 746         if (rc) {
 747                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 748                        "could not register tty - "
 749                        "sclp_register returned %d\n", rc);
 750                 put_tty_driver(driver);
 751                 return rc;
 752         }
 753
 754         driver->owner = THIS_MODULE;
 755         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 756         driver->name = SCLP_VT220_DEVICE_NAME;
 757         driver->major = SCLP_VT220_MAJOR;
 758         driver->minor_start = SCLP_VT220_MINOR;
 759         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 760         driver->subtype = SYSTEM_TYPE_TTY;
 761         driver->init_termios = tty_std_termios;
 762         driver->flags = TTY_DRIVER_REAL_RAW;
 763         tty_set_operations(driver, &sclp_vt220_ops);
 764
 765         rc = tty_register_driver(driver);
 766         if (rc) {
 767                 printk(KERN_ERR SCLP_VT220_PRINT_HEADER
 768                        "could not register tty - "
 769                        "tty_register_driver returned %d\n", rc);
 770                 put_tty_driver(driver);
 771                 return rc;
 772         }
 773         sclp_vt220_driver = driver;
 774         return 0;
 775 }
 776
 777 module_init(sclp_vt220_tty_init);
 778
 779 #ifdef CONFIG_SCLP_VT220_CONSOLE
 780
 781 static void
 782 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 783 {
 784         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1);
 785 }
 786
 787 static struct tty_driver *
 788 sclp_vt220_con_device(struct console *c, int *index)
 789 {
 790         *index = 0;
 791         return sclp_vt220_driver;
 792 }
 793
 794 /*
 795  * This routine is called from panic when the kernel is going to give up.
 796  * We have to make sure that all buffers will be flushed to the SCLP.
 797  * Note that this function may be called from within an interrupt context.
 798  */
 799 static void
 800 sclp_vt220_con_unblank(void)
 801 {
 802         __sclp_vt220_flush_buffer();
 803 }
 804
 805 /* Structure needed to register with printk */
 806 static struct console sclp_vt220_console =
 807 {
 808         .name = SCLP_VT220_CONSOLE_NAME,
 809         .write = sclp_vt220_con_write,
 810         .device = sclp_vt220_con_device,
 811         .unblank = sclp_vt220_con_unblank,
 812         .flags = CON_PRINTBUFFER,
 813         .index = SCLP_VT220_CONSOLE_INDEX
 814 };
 815
 816 static int __init
 817 sclp_vt220_con_init(void)
 818 {
 819         int rc;
 820
 821         if (!CONSOLE_IS_SCLP)
 822                 return 0;
 823         rc = __sclp_vt220_init(1);
 824         if (rc)
 825                 return rc;
 826         /* Attach linux console */
 827         register_console(&sclp_vt220_console);
 828         return 0;
 829 }
 830
 831 console_initcall(sclp_vt220_con_init);
 832 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 833