drivers/s390/char/sclp_vt220.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * SCLP VT220 terminal driver.
   4  *
   5  * Copyright IBM Corp. 2003, 2009
   6  *
   7  * Author(s): Peter Oberparleiter <Peter.Oberparleiter@de.ibm.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/panic_notifier.h>
  13 #include <linux/list.h>
  14 #include <linux/wait.h>
  15 #include <linux/timer.h>
  16 #include <linux/kernel.h>
  17 #include <linux/sysrq.h>
  18 #include <linux/tty.h>
  19 #include <linux/tty_driver.h>
  20 #include <linux/tty_flip.h>
  21 #include <linux/errno.h>
  22 #include <linux/mm.h>
  23 #include <linux/major.h>
  24 #include <linux/console.h>
  25 #include <linux/kdev_t.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/init.h>
  28 #include <linux/reboot.h>
  29 #include <linux/slab.h>
  30
  31 #include <linux/uaccess.h>
  32 #include "sclp.h"
  33 #include "ctrlchar.h"
  34
  35 #define SCLP_VT220_MAJOR                TTY_MAJOR
  36 #define SCLP_VT220_MINOR                65
  37 #define SCLP_VT220_DRIVER_NAME          "sclp_vt220"
  38 #define SCLP_VT220_DEVICE_NAME          "ttysclp"
  39 #define SCLP_VT220_CONSOLE_NAME         "ttysclp"
  40 #define SCLP_VT220_CONSOLE_INDEX        0       /* console=ttysclp0 */
  41
  42 /* Representation of a single write request */
  43 struct sclp_vt220_request {
  44         struct list_head list;
  45         struct sclp_req sclp_req;
  46         int retry_count;
  47 };
  48
  49 /* VT220 SCCB */
  50 struct sclp_vt220_sccb {
  51         struct sccb_header header;
  52         struct evbuf_header evbuf;
  53 };
  54
  55 #define SCLP_VT220_MAX_CHARS_PER_BUFFER (PAGE_SIZE - \
  56                                          sizeof(struct sclp_vt220_request) - \
  57                                          sizeof(struct sclp_vt220_sccb))
  58
  59 /* Structures and data needed to register tty driver */
  60 static struct tty_driver *sclp_vt220_driver;
  61
  62 static struct tty_port sclp_vt220_port;
  63
  64 /* Lock to protect internal data from concurrent access */
  65 static DEFINE_SPINLOCK(sclp_vt220_lock);
  66
  67 /* List of empty pages to be used as write request buffers */
  68 static LIST_HEAD(sclp_vt220_empty);
  69
  70 /* List of pending requests */
  71 static LIST_HEAD(sclp_vt220_outqueue);
  72
  73 /* Flag that output queue is currently running */
  74 static int sclp_vt220_queue_running;
  75
  76 /* Timer used for delaying write requests to merge subsequent messages into
  77  * a single buffer */
  78 static struct timer_list sclp_vt220_timer;
  79
  80 /* Pointer to current request buffer which has been partially filled but not
  81  * yet sent */
  82 static struct sclp_vt220_request *sclp_vt220_current_request;
  83
  84 /* Number of characters in current request buffer */
  85 static int sclp_vt220_buffered_chars;
  86
  87 /* Counter controlling core driver initialization. */
  88 static int __initdata sclp_vt220_init_count;
  89
  90 /* Flag indicating that sclp_vt220_current_request should really
  91  * have been already queued but wasn't because the SCLP was processing
  92  * another buffer */
  93 static int sclp_vt220_flush_later;
  94
  95 static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
  96 static int __sclp_vt220_emit(struct sclp_vt220_request *request);
  97 static void sclp_vt220_emit_current(void);
  98
  99 /* Registration structure for SCLP output event buffers */
 100 static struct sclp_register sclp_vt220_register = {
 101         .send_mask              = EVTYP_VT220MSG_MASK,
 102 };
 103
 104 /* Registration structure for SCLP input event buffers */
 105 static struct sclp_register sclp_vt220_register_input = {
 106         .receive_mask           = EVTYP_VT220MSG_MASK,
 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         void *page;
 120
 121         do {
 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                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 128                 /* Check if there is a pending buffer on the out queue. */
 129                 request = NULL;
 130                 if (!list_empty(&sclp_vt220_outqueue))
 131                         request = list_entry(sclp_vt220_outqueue.next,
 132                                              struct sclp_vt220_request, list);
 133                 if (!request) {
 134                         sclp_vt220_queue_running = 0;
 135                         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 136                         break;
 137                 }
 138                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 139         } while (__sclp_vt220_emit(request));
 140         if (request == NULL && sclp_vt220_flush_later)
 141                 sclp_vt220_emit_current();
 142         tty_port_tty_wakeup(&sclp_vt220_port);
 143 }
 144
 145 #define SCLP_BUFFER_MAX_RETRY           1
 146
 147 /*
 148  * Callback through which the result of a write request is reported by the
 149  * SCLP.
 150  */
 151 static void
 152 sclp_vt220_callback(struct sclp_req *request, void *data)
 153 {
 154         struct sclp_vt220_request *vt220_request;
 155         struct sclp_vt220_sccb *sccb;
 156
 157         vt220_request = (struct sclp_vt220_request *) data;
 158         if (request->status == SCLP_REQ_FAILED) {
 159                 sclp_vt220_process_queue(vt220_request);
 160                 return;
 161         }
 162         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
 163
 164         /* Check SCLP response code and choose suitable action  */
 165         switch (sccb->header.response_code) {
 166         case 0x0020 :
 167                 break;
 168
 169         case 0x05f0: /* Target resource in improper state */
 170                 break;
 171
 172         case 0x0340: /* Contained SCLP equipment check */
 173                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 174                         break;
 175                 /* Remove processed buffers and requeue rest */
 176                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 177                         /* Not all buffers were processed */
 178                         sccb->header.response_code = 0x0000;
 179                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 180                         if (sclp_add_request(request) == 0)
 181                                 return;
 182                 }
 183                 break;
 184
 185         case 0x0040: /* SCLP equipment check */
 186                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 187                         break;
 188                 sccb->header.response_code = 0x0000;
 189                 vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 190                 if (sclp_add_request(request) == 0)
 191                         return;
 192                 break;
 193
 194         default:
 195                 break;
 196         }
 197         sclp_vt220_process_queue(vt220_request);
 198 }
 199
 200 /*
 201  * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
 202  * otherwise.
 203  */
 204 static int
 205 __sclp_vt220_emit(struct sclp_vt220_request *request)
 206 {
 207         request->sclp_req.command = SCLP_CMDW_WRITE_EVENT_DATA;
 208         request->sclp_req.status = SCLP_REQ_FILLED;
 209         request->sclp_req.callback = sclp_vt220_callback;
 210         request->sclp_req.callback_data = (void *) request;
 211
 212         return sclp_add_request(&request->sclp_req);
 213 }
 214
 215 /*
 216  * Queue and emit current request.
 217  */
 218 static void
 219 sclp_vt220_emit_current(void)
 220 {
 221         unsigned long flags;
 222         struct sclp_vt220_request *request;
 223         struct sclp_vt220_sccb *sccb;
 224
 225         spin_lock_irqsave(&sclp_vt220_lock, flags);
 226         if (sclp_vt220_current_request) {
 227                 sccb = (struct sclp_vt220_sccb *)
 228                                 sclp_vt220_current_request->sclp_req.sccb;
 229                 /* Only emit buffers with content */
 230                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 231                         list_add_tail(&sclp_vt220_current_request->list,
 232                                       &sclp_vt220_outqueue);
 233                         sclp_vt220_current_request = NULL;
 234                         del_timer(&sclp_vt220_timer);
 235                 }
 236                 sclp_vt220_flush_later = 0;
 237         }
 238         if (sclp_vt220_queue_running)
 239                 goto out_unlock;
 240         if (list_empty(&sclp_vt220_outqueue))
 241                 goto out_unlock;
 242         request = list_first_entry(&sclp_vt220_outqueue,
 243                                    struct sclp_vt220_request, list);
 244         sclp_vt220_queue_running = 1;
 245         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 246
 247         if (__sclp_vt220_emit(request))
 248                 sclp_vt220_process_queue(request);
 249         return;
 250 out_unlock:
 251         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 252 }
 253
 254 #define SCLP_NORMAL_WRITE       0x00
 255
 256 /*
 257  * Helper function to initialize a page with the sclp request structure.
 258  */
 259 static struct sclp_vt220_request *
 260 sclp_vt220_initialize_page(void *page)
 261 {
 262         struct sclp_vt220_request *request;
 263         struct sclp_vt220_sccb *sccb;
 264
 265         /* Place request structure at end of page */
 266         request = ((struct sclp_vt220_request *)
 267                         ((addr_t) page + PAGE_SIZE)) - 1;
 268         request->retry_count = 0;
 269         request->sclp_req.sccb = page;
 270         /* SCCB goes at start of page */
 271         sccb = (struct sclp_vt220_sccb *) page;
 272         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
 273         sccb->header.length = sizeof(struct sclp_vt220_sccb);
 274         sccb->header.function_code = SCLP_NORMAL_WRITE;
 275         sccb->header.response_code = 0x0000;
 276         sccb->evbuf.type = EVTYP_VT220MSG;
 277         sccb->evbuf.length = sizeof(struct evbuf_header);
 278
 279         return request;
 280 }
 281
 282 static inline unsigned int
 283 sclp_vt220_space_left(struct sclp_vt220_request *request)
 284 {
 285         struct sclp_vt220_sccb *sccb;
 286         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 287         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
 288                sccb->header.length;
 289 }
 290
 291 static inline unsigned int
 292 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
 293 {
 294         struct sclp_vt220_sccb *sccb;
 295         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 296         return sccb->evbuf.length - sizeof(struct evbuf_header);
 297 }
 298
 299 /*
 300  * Add msg to buffer associated with request. Return the number of characters
 301  * added.
 302  */
 303 static int
 304 sclp_vt220_add_msg(struct sclp_vt220_request *request,
 305                    const unsigned char *msg, int count, int convertlf)
 306 {
 307         struct sclp_vt220_sccb *sccb;
 308         void *buffer;
 309         unsigned char c;
 310         int from;
 311         int to;
 312
 313         if (count > sclp_vt220_space_left(request))
 314                 count = sclp_vt220_space_left(request);
 315         if (count <= 0)
 316                 return 0;
 317
 318         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 319         buffer = (void *) ((addr_t) sccb + sccb->header.length);
 320
 321         if (convertlf) {
 322                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
 323                 for (from=0, to=0;
 324                      (from < count) && (to < sclp_vt220_space_left(request));
 325                      from++) {
 326                         /* Retrieve character */
 327                         c = msg[from];
 328                         /* Perform conversion */
 329                         if (c == 0x0a) {
 330                                 if (to + 1 < sclp_vt220_space_left(request)) {
 331                                         ((unsigned char *) buffer)[to++] = c;
 332                                         ((unsigned char *) buffer)[to++] = 0x0d;
 333                                 } else
 334                                         break;
 335
 336                         } else
 337                                 ((unsigned char *) buffer)[to++] = c;
 338                 }
 339                 sccb->header.length += to;
 340                 sccb->evbuf.length += to;
 341                 return from;
 342         } else {
 343                 memcpy(buffer, (const void *) msg, count);
 344                 sccb->header.length += count;
 345                 sccb->evbuf.length += count;
 346                 return count;
 347         }
 348 }
 349
 350 /*
 351  * Emit buffer after having waited long enough for more data to arrive.
 352  */
 353 static void
 354 sclp_vt220_timeout(struct timer_list *unused)
 355 {
 356         sclp_vt220_emit_current();
 357 }
 358
 359 #define BUFFER_MAX_DELAY        HZ/20
 360
 361 /*
 362  * Drop oldest console buffer if sclp_con_drop is set
 363  */
 364 static int
 365 sclp_vt220_drop_buffer(void)
 366 {
 367         struct list_head *list;
 368         struct sclp_vt220_request *request;
 369         void *page;
 370
 371         if (!sclp_console_drop)
 372                 return 0;
 373         list = sclp_vt220_outqueue.next;
 374         if (sclp_vt220_queue_running)
 375                 /* The first element is in I/O */
 376                 list = list->next;
 377         if (list == &sclp_vt220_outqueue)
 378                 return 0;
 379         list_del(list);
 380         request = list_entry(list, struct sclp_vt220_request, list);
 381         page = request->sclp_req.sccb;
 382         list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 383         return 1;
 384 }
 385
 386 /*
 387  * Internal implementation of the write function. Write COUNT bytes of data
 388  * from memory at BUF
 389  * to the SCLP interface. In case that the data does not fit into the current
 390  * write buffer, emit the current one and allocate a new one. If there are no
 391  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 392  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 393  * otherwise the user has to explicitly call the flush function.
 394  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 395  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 396  * of bytes written.
 397  */
 398 static int
 399 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 400                    int convertlf, int may_fail)
 401 {
 402         unsigned long flags;
 403         void *page;
 404         int written;
 405         int overall_written;
 406
 407         if (count <= 0)
 408                 return 0;
 409         overall_written = 0;
 410         spin_lock_irqsave(&sclp_vt220_lock, flags);
 411         do {
 412                 /* Create an sclp output buffer if none exists yet */
 413                 if (sclp_vt220_current_request == NULL) {
 414                         if (list_empty(&sclp_vt220_empty))
 415                                 sclp_console_full++;
 416                         while (list_empty(&sclp_vt220_empty)) {
 417                                 if (may_fail)
 418                                         goto out;
 419                                 if (sclp_vt220_drop_buffer())
 420                                         break;
 421                                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 422
 423                                 sclp_sync_wait();
 424                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 425                         }
 426                         page = (void *) sclp_vt220_empty.next;
 427                         list_del((struct list_head *) page);
 428                         sclp_vt220_current_request =
 429                                 sclp_vt220_initialize_page(page);
 430                 }
 431                 /* Try to write the string to the current request buffer */
 432                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 433                                              buf, count, convertlf);
 434                 overall_written += written;
 435                 if (written == count)
 436                         break;
 437                 /*
 438                  * Not all characters could be written to the current
 439                  * output buffer. Emit the buffer, create a new buffer
 440                  * and then output the rest of the string.
 441                  */
 442                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 443                 sclp_vt220_emit_current();
 444                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 445                 buf += written;
 446                 count -= written;
 447         } while (count > 0);
 448         /* Setup timer to output current console buffer after some time */
 449         if (sclp_vt220_current_request != NULL &&
 450             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 451                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 452                 add_timer(&sclp_vt220_timer);
 453         }
 454 out:
 455         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 456         return overall_written;
 457 }
 458
 459 /*
 460  * This routine is called by the kernel to write a series of
 461  * characters to the tty device.  The characters may come from
 462  * user space or kernel space.  This routine will return the
 463  * number of characters actually accepted for writing.
 464  */
 465 static ssize_t
 466 sclp_vt220_write(struct tty_struct *tty, const u8 *buf, size_t count)
 467 {
 468         return __sclp_vt220_write(buf, count, 1, 0, 1);
 469 }
 470
 471 #define SCLP_VT220_SESSION_ENDED        0x01
 472 #define SCLP_VT220_SESSION_STARTED      0x80
 473 #define SCLP_VT220_SESSION_DATA         0x00
 474
 475 #ifdef CONFIG_MAGIC_SYSRQ
 476
 477 static int sysrq_pressed;
 478 static struct sysrq_work sysrq;
 479
 480 static void sclp_vt220_reset_session(void)
 481 {
 482         sysrq_pressed = 0;
 483 }
 484
 485 static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
 486 {
 487         int i;
 488
 489         for (i = 0; i < count; i++) {
 490                 /* Handle magic sys request */
 491                 if (buffer[i] == ('O' ^ 0100)) { /* CTRL-O */
 492                         /*
 493                          * If pressed again, reset sysrq_pressed
 494                          * and flip CTRL-O character
 495                          */
 496                         sysrq_pressed = !sysrq_pressed;
 497                         if (sysrq_pressed)
 498                                 continue;
 499                 } else if (sysrq_pressed) {
 500                         sysrq.key = buffer[i];
 501                         schedule_sysrq_work(&sysrq);
 502                         sysrq_pressed = 0;
 503                         continue;
 504                 }
 505                 tty_insert_flip_char(&sclp_vt220_port, buffer[i], 0);
 506         }
 507 }
 508
 509 #else
 510
 511 static void sclp_vt220_reset_session(void)
 512 {
 513 }
 514
 515 static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
 516 {
 517         tty_insert_flip_string(&sclp_vt220_port, buffer, count);
 518 }
 519
 520 #endif
 521
 522 /*
 523  * Called by the SCLP to report incoming event buffers.
 524  */
 525 static void
 526 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 527 {
 528         char *buffer;
 529         unsigned int count;
 530
 531         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 532         count = evbuf->length - sizeof(struct evbuf_header);
 533
 534         switch (*buffer) {
 535         case SCLP_VT220_SESSION_ENDED:
 536         case SCLP_VT220_SESSION_STARTED:
 537                 sclp_vt220_reset_session();
 538                 break;
 539         case SCLP_VT220_SESSION_DATA:
 540                 /* Send input to line discipline */
 541                 buffer++;
 542                 count--;
 543                 sclp_vt220_handle_input(buffer, count);
 544                 tty_flip_buffer_push(&sclp_vt220_port);
 545                 break;
 546         }
 547 }
 548
 549 /*
 550  * This routine is called when a particular tty device is opened.
 551  */
 552 static int
 553 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 554 {
 555         if (tty->count == 1) {
 556                 tty_port_tty_set(&sclp_vt220_port, tty);
 557                 if (!tty->winsize.ws_row && !tty->winsize.ws_col) {
 558                         tty->winsize.ws_row = 24;
 559                         tty->winsize.ws_col = 80;
 560                 }
 561         }
 562         return 0;
 563 }
 564
 565 /*
 566  * This routine is called when a particular tty device is closed.
 567  */
 568 static void
 569 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 570 {
 571         if (tty->count == 1)
 572                 tty_port_tty_set(&sclp_vt220_port, NULL);
 573 }
 574
 575 /*
 576  * This routine is called by the kernel to write a single
 577  * character to the tty device.  If the kernel uses this routine,
 578  * it must call the flush_chars() routine (if defined) when it is
 579  * done stuffing characters into the driver.
 580  */
 581 static int
 582 sclp_vt220_put_char(struct tty_struct *tty, u8 ch)
 583 {
 584         return __sclp_vt220_write(&ch, 1, 0, 0, 1);
 585 }
 586
 587 /*
 588  * This routine is called by the kernel after it has written a
 589  * series of characters to the tty device using put_char().
 590  */
 591 static void
 592 sclp_vt220_flush_chars(struct tty_struct *tty)
 593 {
 594         if (!sclp_vt220_queue_running)
 595                 sclp_vt220_emit_current();
 596         else
 597                 sclp_vt220_flush_later = 1;
 598 }
 599
 600 /*
 601  * This routine returns the numbers of characters the tty driver
 602  * will accept for queuing to be written.  This number is subject
 603  * to change as output buffers get emptied, or if the output flow
 604  * control is acted.
 605  */
 606 static unsigned int
 607 sclp_vt220_write_room(struct tty_struct *tty)
 608 {
 609         unsigned long flags;
 610         struct list_head *l;
 611         unsigned int count;
 612
 613         spin_lock_irqsave(&sclp_vt220_lock, flags);
 614         count = 0;
 615         if (sclp_vt220_current_request != NULL)
 616                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 617         list_for_each(l, &sclp_vt220_empty)
 618                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 619         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 620         return count;
 621 }
 622
 623 /*
 624  * Return number of buffered chars.
 625  */
 626 static unsigned int
 627 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 628 {
 629         unsigned long flags;
 630         struct list_head *l;
 631         struct sclp_vt220_request *r;
 632         unsigned int count = 0;
 633
 634         spin_lock_irqsave(&sclp_vt220_lock, flags);
 635         if (sclp_vt220_current_request != NULL)
 636                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 637         list_for_each(l, &sclp_vt220_outqueue) {
 638                 r = list_entry(l, struct sclp_vt220_request, list);
 639                 count += sclp_vt220_chars_stored(r);
 640         }
 641         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 642         return count;
 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 /* Release allocated pages. */
 656 static void __init __sclp_vt220_free_pages(void)
 657 {
 658         struct list_head *page, *p;
 659
 660         list_for_each_safe(page, p, &sclp_vt220_empty) {
 661                 list_del(page);
 662                 free_page((unsigned long) page);
 663         }
 664 }
 665
 666 /* Release memory and unregister from sclp core. Controlled by init counting -
 667  * only the last invoker will actually perform these actions. */
 668 static void __init __sclp_vt220_cleanup(void)
 669 {
 670         sclp_vt220_init_count--;
 671         if (sclp_vt220_init_count != 0)
 672                 return;
 673         sclp_unregister(&sclp_vt220_register);
 674         __sclp_vt220_free_pages();
 675         tty_port_destroy(&sclp_vt220_port);
 676 }
 677
 678 /* Allocate buffer pages and register with sclp core. Controlled by init
 679  * counting - only the first invoker will actually perform these actions. */
 680 static int __init __sclp_vt220_init(int num_pages)
 681 {
 682         void *page;
 683         int i;
 684         int rc;
 685
 686         sclp_vt220_init_count++;
 687         if (sclp_vt220_init_count != 1)
 688                 return 0;
 689         timer_setup(&sclp_vt220_timer, sclp_vt220_timeout, 0);
 690         tty_port_init(&sclp_vt220_port);
 691         sclp_vt220_current_request = NULL;
 692         sclp_vt220_buffered_chars = 0;
 693         sclp_vt220_flush_later = 0;
 694
 695         /* Allocate pages for output buffering */
 696         rc = -ENOMEM;
 697         for (i = 0; i < num_pages; i++) {
 698                 page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 699                 if (!page)
 700                         goto out;
 701                 list_add_tail(page, &sclp_vt220_empty);
 702         }
 703         rc = sclp_register(&sclp_vt220_register);
 704 out:
 705         if (rc) {
 706                 __sclp_vt220_free_pages();
 707                 sclp_vt220_init_count--;
 708                 tty_port_destroy(&sclp_vt220_port);
 709         }
 710         return rc;
 711 }
 712
 713 static const struct tty_operations sclp_vt220_ops = {
 714         .open = sclp_vt220_open,
 715         .close = sclp_vt220_close,
 716         .write = sclp_vt220_write,
 717         .put_char = sclp_vt220_put_char,
 718         .flush_chars = sclp_vt220_flush_chars,
 719         .write_room = sclp_vt220_write_room,
 720         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 721         .flush_buffer = sclp_vt220_flush_buffer,
 722 };
 723
 724 /*
 725  * Register driver with SCLP and Linux and initialize internal tty structures.
 726  */
 727 static int __init sclp_vt220_tty_init(void)
 728 {
 729         struct tty_driver *driver;
 730         int rc;
 731
 732         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 733          * symmetry between VM and LPAR systems regarding ttyS1. */
 734         driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW);
 735         if (IS_ERR(driver))
 736                 return PTR_ERR(driver);
 737         rc = __sclp_vt220_init(MAX_KMEM_PAGES);
 738         if (rc)
 739                 goto out_driver;
 740
 741         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 742         driver->name = SCLP_VT220_DEVICE_NAME;
 743         driver->major = SCLP_VT220_MAJOR;
 744         driver->minor_start = SCLP_VT220_MINOR;
 745         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 746         driver->subtype = SYSTEM_TYPE_TTY;
 747         driver->init_termios = tty_std_termios;
 748         tty_set_operations(driver, &sclp_vt220_ops);
 749         tty_port_link_device(&sclp_vt220_port, driver, 0);
 750
 751         rc = tty_register_driver(driver);
 752         if (rc)
 753                 goto out_init;
 754         rc = sclp_register(&sclp_vt220_register_input);
 755         if (rc)
 756                 goto out_reg;
 757         sclp_vt220_driver = driver;
 758         return 0;
 759
 760 out_reg:
 761         tty_unregister_driver(driver);
 762 out_init:
 763         __sclp_vt220_cleanup();
 764 out_driver:
 765         tty_driver_kref_put(driver);
 766         return rc;
 767 }
 768 __initcall(sclp_vt220_tty_init);
 769
 770 #ifdef CONFIG_SCLP_VT220_CONSOLE
 771
 772 static void
 773 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 774 {
 775         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1, 0);
 776 }
 777
 778 static struct tty_driver *
 779 sclp_vt220_con_device(struct console *c, int *index)
 780 {
 781         *index = 0;
 782         return sclp_vt220_driver;
 783 }
 784
 785 /*
 786  * This panic/reboot notifier runs in atomic context, so
 787  * locking restrictions apply to prevent potential lockups.
 788  */
 789 static int
 790 sclp_vt220_notify(struct notifier_block *self,
 791                           unsigned long event, void *data)
 792 {
 793         unsigned long flags;
 794
 795         if (spin_is_locked(&sclp_vt220_lock))
 796                 return NOTIFY_DONE;
 797
 798         sclp_vt220_emit_current();
 799
 800         spin_lock_irqsave(&sclp_vt220_lock, flags);
 801         del_timer(&sclp_vt220_timer);
 802         while (sclp_vt220_queue_running) {
 803                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 804                 sclp_sync_wait();
 805                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 806         }
 807         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 808
 809         return NOTIFY_DONE;
 810 }
 811
 812 static struct notifier_block on_panic_nb = {
 813         .notifier_call = sclp_vt220_notify,
 814         .priority = INT_MIN + 1, /* run the callback late */
 815 };
 816
 817 static struct notifier_block on_reboot_nb = {
 818         .notifier_call = sclp_vt220_notify,
 819         .priority = INT_MIN + 1, /* run the callback late */
 820 };
 821
 822 /* Structure needed to register with printk */
 823 static struct console sclp_vt220_console =
 824 {
 825         .name = SCLP_VT220_CONSOLE_NAME,
 826         .write = sclp_vt220_con_write,
 827         .device = sclp_vt220_con_device,
 828         .flags = CON_PRINTBUFFER,
 829         .index = SCLP_VT220_CONSOLE_INDEX
 830 };
 831
 832 static int __init
 833 sclp_vt220_con_init(void)
 834 {
 835         int rc;
 836
 837         rc = __sclp_vt220_init(sclp_console_pages);
 838         if (rc)
 839                 return rc;
 840         /* Attach linux console */
 841         atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
 842         register_reboot_notifier(&on_reboot_nb);
 843         register_console(&sclp_vt220_console);
 844         return 0;
 845 }
 846
 847 console_initcall(sclp_vt220_con_init);
 848 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 849