kernel/drivers/s390/char/sclp_vt220.c

   1 /*
   2  * SCLP VT220 terminal driver.
   3  *
   4  * Copyright IBM Corp. 2003, 2009
   5  *
   6  * Author(s): Peter Oberparleiter <Peter.Oberparleiter@de.ibm.com>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/list.h>
  12 #include <linux/wait.h>
  13 #include <linux/timer.h>
  14 #include <linux/kernel.h>
  15 #include <linux/sysrq.h>
  16 #include <linux/tty.h>
  17 #include <linux/tty_driver.h>
  18 #include <linux/tty_flip.h>
  19 #include <linux/errno.h>
  20 #include <linux/mm.h>
  21 #include <linux/major.h>
  22 #include <linux/console.h>
  23 #include <linux/kdev_t.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/init.h>
  26 #include <linux/reboot.h>
  27 #include <linux/slab.h>
  28
  29 #include <asm/uaccess.h>
  30 #include "sclp.h"
  31 #include "ctrlchar.h"
  32
  33 #define SCLP_VT220_MAJOR                TTY_MAJOR
  34 #define SCLP_VT220_MINOR                65
  35 #define SCLP_VT220_DRIVER_NAME          "sclp_vt220"
  36 #define SCLP_VT220_DEVICE_NAME          "ttysclp"
  37 #define SCLP_VT220_CONSOLE_NAME         "ttyS"
  38 #define SCLP_VT220_CONSOLE_INDEX        1       /* console=ttyS1 */
  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 };
  46
  47 /* VT220 SCCB */
  48 struct sclp_vt220_sccb {
  49         struct sccb_header header;
  50         struct evbuf_header evbuf;
  51 };
  52
  53 #define SCLP_VT220_MAX_CHARS_PER_BUFFER (PAGE_SIZE - \
  54                                          sizeof(struct sclp_vt220_request) - \
  55                                          sizeof(struct sclp_vt220_sccb))
  56
  57 /* Structures and data needed to register tty driver */
  58 static struct tty_driver *sclp_vt220_driver;
  59
  60 static struct tty_port sclp_vt220_port;
  61
  62 /* Lock to protect internal data from concurrent access */
  63 static spinlock_t sclp_vt220_lock;
  64
  65 /* List of empty pages to be used as write request buffers */
  66 static struct list_head sclp_vt220_empty;
  67
  68 /* List of pending requests */
  69 static struct list_head sclp_vt220_outqueue;
  70
  71 /* Suspend mode flag */
  72 static int sclp_vt220_suspended;
  73
  74 /* Flag that output queue is currently running */
  75 static int sclp_vt220_queue_running;
  76
  77 /* Timer used for delaying write requests to merge subsequent messages into
  78  * a single buffer */
  79 static struct timer_list sclp_vt220_timer;
  80
  81 /* Pointer to current request buffer which has been partially filled but not
  82  * yet sent */
  83 static struct sclp_vt220_request *sclp_vt220_current_request;
  84
  85 /* Number of characters in current request buffer */
  86 static int sclp_vt220_buffered_chars;
  87
  88 /* Counter controlling core driver initialization. */
  89 static int __initdata sclp_vt220_init_count;
  90
  91 /* Flag indicating that sclp_vt220_current_request should really
  92  * have been already queued but wasn't because the SCLP was processing
  93  * another buffer */
  94 static int sclp_vt220_flush_later;
  95
  96 static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
  97 static void sclp_vt220_pm_event_fn(struct sclp_register *reg,
  98                                    enum sclp_pm_event sclp_pm_event);
  99 static int __sclp_vt220_emit(struct sclp_vt220_request *request);
 100 static void sclp_vt220_emit_current(void);
 101
 102 /* Registration structure for SCLP output event buffers */
 103 static struct sclp_register sclp_vt220_register = {
 104         .send_mask              = EVTYP_VT220MSG_MASK,
 105         .pm_event_fn            = sclp_vt220_pm_event_fn,
 106 };
 107
 108 /* Registration structure for SCLP input event buffers */
 109 static struct sclp_register sclp_vt220_register_input = {
 110         .receive_mask           = EVTYP_VT220MSG_MASK,
 111         .receiver_fn            = sclp_vt220_receiver_fn,
 112 };
 113
 114
 115 /*
 116  * Put provided request buffer back into queue and check emit pending
 117  * buffers if necessary.
 118  */
 119 static void
 120 sclp_vt220_process_queue(struct sclp_vt220_request *request)
 121 {
 122         unsigned long flags;
 123         void *page;
 124
 125         do {
 126                 /* Put buffer back to list of empty buffers */
 127                 page = request->sclp_req.sccb;
 128                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 129                 /* Move request from outqueue to empty queue */
 130                 list_del(&request->list);
 131                 list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 132                 /* Check if there is a pending buffer on the out queue. */
 133                 request = NULL;
 134                 if (!list_empty(&sclp_vt220_outqueue))
 135                         request = list_entry(sclp_vt220_outqueue.next,
 136                                              struct sclp_vt220_request, list);
 137                 if (!request || sclp_vt220_suspended) {
 138                         sclp_vt220_queue_running = 0;
 139                         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 140                         break;
 141                 }
 142                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 143         } while (__sclp_vt220_emit(request));
 144         if (request == NULL && sclp_vt220_flush_later)
 145                 sclp_vt220_emit_current();
 146         tty_port_tty_wakeup(&sclp_vt220_port);
 147 }
 148
 149 #define SCLP_BUFFER_MAX_RETRY           1
 150
 151 /*
 152  * Callback through which the result of a write request is reported by the
 153  * SCLP.
 154  */
 155 static void
 156 sclp_vt220_callback(struct sclp_req *request, void *data)
 157 {
 158         struct sclp_vt220_request *vt220_request;
 159         struct sclp_vt220_sccb *sccb;
 160
 161         vt220_request = (struct sclp_vt220_request *) data;
 162         if (request->status == SCLP_REQ_FAILED) {
 163                 sclp_vt220_process_queue(vt220_request);
 164                 return;
 165         }
 166         sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
 167
 168         /* Check SCLP response code and choose suitable action  */
 169         switch (sccb->header.response_code) {
 170         case 0x0020 :
 171                 break;
 172
 173         case 0x05f0: /* Target resource in improper state */
 174                 break;
 175
 176         case 0x0340: /* Contained SCLP equipment check */
 177                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 178                         break;
 179                 /* Remove processed buffers and requeue rest */
 180                 if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
 181                         /* Not all buffers were processed */
 182                         sccb->header.response_code = 0x0000;
 183                         vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 184                         if (sclp_add_request(request) == 0)
 185                                 return;
 186                 }
 187                 break;
 188
 189         case 0x0040: /* SCLP equipment check */
 190                 if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
 191                         break;
 192                 sccb->header.response_code = 0x0000;
 193                 vt220_request->sclp_req.status = SCLP_REQ_FILLED;
 194                 if (sclp_add_request(request) == 0)
 195                         return;
 196                 break;
 197
 198         default:
 199                 break;
 200         }
 201         sclp_vt220_process_queue(vt220_request);
 202 }
 203
 204 /*
 205  * Emit vt220 request buffer to SCLP. Return zero on success, non-zero
 206  * otherwise.
 207  */
 208 static int
 209 __sclp_vt220_emit(struct sclp_vt220_request *request)
 210 {
 211         request->sclp_req.command = SCLP_CMDW_WRITE_EVENT_DATA;
 212         request->sclp_req.status = SCLP_REQ_FILLED;
 213         request->sclp_req.callback = sclp_vt220_callback;
 214         request->sclp_req.callback_data = (void *) request;
 215
 216         return sclp_add_request(&request->sclp_req);
 217 }
 218
 219 /*
 220  * Queue and emit current request.
 221  */
 222 static void
 223 sclp_vt220_emit_current(void)
 224 {
 225         unsigned long flags;
 226         struct sclp_vt220_request *request;
 227         struct sclp_vt220_sccb *sccb;
 228
 229         spin_lock_irqsave(&sclp_vt220_lock, flags);
 230         if (sclp_vt220_current_request) {
 231                 sccb = (struct sclp_vt220_sccb *)
 232                                 sclp_vt220_current_request->sclp_req.sccb;
 233                 /* Only emit buffers with content */
 234                 if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
 235                         list_add_tail(&sclp_vt220_current_request->list,
 236                                       &sclp_vt220_outqueue);
 237                         sclp_vt220_current_request = NULL;
 238                         if (timer_pending(&sclp_vt220_timer))
 239                                 del_timer(&sclp_vt220_timer);
 240                 }
 241                 sclp_vt220_flush_later = 0;
 242         }
 243         if (sclp_vt220_queue_running || sclp_vt220_suspended)
 244                 goto out_unlock;
 245         if (list_empty(&sclp_vt220_outqueue))
 246                 goto out_unlock;
 247         request = list_first_entry(&sclp_vt220_outqueue,
 248                                    struct sclp_vt220_request, list);
 249         sclp_vt220_queue_running = 1;
 250         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 251
 252         if (__sclp_vt220_emit(request))
 253                 sclp_vt220_process_queue(request);
 254         return;
 255 out_unlock:
 256         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 257 }
 258
 259 #define SCLP_NORMAL_WRITE       0x00
 260
 261 /*
 262  * Helper function to initialize a page with the sclp request structure.
 263  */
 264 static struct sclp_vt220_request *
 265 sclp_vt220_initialize_page(void *page)
 266 {
 267         struct sclp_vt220_request *request;
 268         struct sclp_vt220_sccb *sccb;
 269
 270         /* Place request structure at end of page */
 271         request = ((struct sclp_vt220_request *)
 272                         ((addr_t) page + PAGE_SIZE)) - 1;
 273         request->retry_count = 0;
 274         request->sclp_req.sccb = page;
 275         /* SCCB goes at start of page */
 276         sccb = (struct sclp_vt220_sccb *) page;
 277         memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
 278         sccb->header.length = sizeof(struct sclp_vt220_sccb);
 279         sccb->header.function_code = SCLP_NORMAL_WRITE;
 280         sccb->header.response_code = 0x0000;
 281         sccb->evbuf.type = EVTYP_VT220MSG;
 282         sccb->evbuf.length = sizeof(struct evbuf_header);
 283
 284         return request;
 285 }
 286
 287 static inline unsigned int
 288 sclp_vt220_space_left(struct sclp_vt220_request *request)
 289 {
 290         struct sclp_vt220_sccb *sccb;
 291         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 292         return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
 293                sccb->header.length;
 294 }
 295
 296 static inline unsigned int
 297 sclp_vt220_chars_stored(struct sclp_vt220_request *request)
 298 {
 299         struct sclp_vt220_sccb *sccb;
 300         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 301         return sccb->evbuf.length - sizeof(struct evbuf_header);
 302 }
 303
 304 /*
 305  * Add msg to buffer associated with request. Return the number of characters
 306  * added.
 307  */
 308 static int
 309 sclp_vt220_add_msg(struct sclp_vt220_request *request,
 310                    const unsigned char *msg, int count, int convertlf)
 311 {
 312         struct sclp_vt220_sccb *sccb;
 313         void *buffer;
 314         unsigned char c;
 315         int from;
 316         int to;
 317
 318         if (count > sclp_vt220_space_left(request))
 319                 count = sclp_vt220_space_left(request);
 320         if (count <= 0)
 321                 return 0;
 322
 323         sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
 324         buffer = (void *) ((addr_t) sccb + sccb->header.length);
 325
 326         if (convertlf) {
 327                 /* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
 328                 for (from=0, to=0;
 329                      (from < count) && (to < sclp_vt220_space_left(request));
 330                      from++) {
 331                         /* Retrieve character */
 332                         c = msg[from];
 333                         /* Perform conversion */
 334                         if (c == 0x0a) {
 335                                 if (to + 1 < sclp_vt220_space_left(request)) {
 336                                         ((unsigned char *) buffer)[to++] = c;
 337                                         ((unsigned char *) buffer)[to++] = 0x0d;
 338                                 } else
 339                                         break;
 340
 341                         } else
 342                                 ((unsigned char *) buffer)[to++] = c;
 343                 }
 344                 sccb->header.length += to;
 345                 sccb->evbuf.length += to;
 346                 return from;
 347         } else {
 348                 memcpy(buffer, (const void *) msg, count);
 349                 sccb->header.length += count;
 350                 sccb->evbuf.length += count;
 351                 return count;
 352         }
 353 }
 354
 355 /*
 356  * Emit buffer after having waited long enough for more data to arrive.
 357  */
 358 static void
 359 sclp_vt220_timeout(unsigned long data)
 360 {
 361         sclp_vt220_emit_current();
 362 }
 363
 364 #define BUFFER_MAX_DELAY        HZ/20
 365
 366 /*
 367  * Drop oldest console buffer if sclp_con_drop is set
 368  */
 369 static int
 370 sclp_vt220_drop_buffer(void)
 371 {
 372         struct list_head *list;
 373         struct sclp_vt220_request *request;
 374         void *page;
 375
 376         if (!sclp_console_drop)
 377                 return 0;
 378         list = sclp_vt220_outqueue.next;
 379         if (sclp_vt220_queue_running)
 380                 /* The first element is in I/O */
 381                 list = list->next;
 382         if (list == &sclp_vt220_outqueue)
 383                 return 0;
 384         list_del(list);
 385         request = list_entry(list, struct sclp_vt220_request, list);
 386         page = request->sclp_req.sccb;
 387         list_add_tail((struct list_head *) page, &sclp_vt220_empty);
 388         return 1;
 389 }
 390
 391 /*
 392  * Internal implementation of the write function. Write COUNT bytes of data
 393  * from memory at BUF
 394  * to the SCLP interface. In case that the data does not fit into the current
 395  * write buffer, emit the current one and allocate a new one. If there are no
 396  * more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
 397  * is non-zero, the buffer will be scheduled for emitting after a timeout -
 398  * otherwise the user has to explicitly call the flush function.
 399  * A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
 400  * buffer should be converted to 0x0a 0x0d. After completion, return the number
 401  * of bytes written.
 402  */
 403 static int
 404 __sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
 405                    int convertlf, int may_fail)
 406 {
 407         unsigned long flags;
 408         void *page;
 409         int written;
 410         int overall_written;
 411
 412         if (count <= 0)
 413                 return 0;
 414         overall_written = 0;
 415         spin_lock_irqsave(&sclp_vt220_lock, flags);
 416         do {
 417                 /* Create an sclp output buffer if none exists yet */
 418                 if (sclp_vt220_current_request == NULL) {
 419                         if (list_empty(&sclp_vt220_empty))
 420                                 sclp_console_full++;
 421                         while (list_empty(&sclp_vt220_empty)) {
 422                                 if (may_fail || sclp_vt220_suspended)
 423                                         goto out;
 424                                 if (sclp_vt220_drop_buffer())
 425                                         break;
 426                                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 427
 428                                 sclp_sync_wait();
 429                                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 430                         }
 431                         page = (void *) sclp_vt220_empty.next;
 432                         list_del((struct list_head *) page);
 433                         sclp_vt220_current_request =
 434                                 sclp_vt220_initialize_page(page);
 435                 }
 436                 /* Try to write the string to the current request buffer */
 437                 written = sclp_vt220_add_msg(sclp_vt220_current_request,
 438                                              buf, count, convertlf);
 439                 overall_written += written;
 440                 if (written == count)
 441                         break;
 442                 /*
 443                  * Not all characters could be written to the current
 444                  * output buffer. Emit the buffer, create a new buffer
 445                  * and then output the rest of the string.
 446                  */
 447                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 448                 sclp_vt220_emit_current();
 449                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 450                 buf += written;
 451                 count -= written;
 452         } while (count > 0);
 453         /* Setup timer to output current console buffer after some time */
 454         if (sclp_vt220_current_request != NULL &&
 455             !timer_pending(&sclp_vt220_timer) && do_schedule) {
 456                 sclp_vt220_timer.function = sclp_vt220_timeout;
 457                 sclp_vt220_timer.data = 0UL;
 458                 sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
 459                 add_timer(&sclp_vt220_timer);
 460         }
 461 out:
 462         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 463         return overall_written;
 464 }
 465
 466 /*
 467  * This routine is called by the kernel to write a series of
 468  * characters to the tty device.  The characters may come from
 469  * user space or kernel space.  This routine will return the
 470  * number of characters actually accepted for writing.
 471  */
 472 static int
 473 sclp_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
 474 {
 475         return __sclp_vt220_write(buf, count, 1, 0, 1);
 476 }
 477
 478 #define SCLP_VT220_SESSION_ENDED        0x01
 479 #define SCLP_VT220_SESSION_STARTED      0x80
 480 #define SCLP_VT220_SESSION_DATA         0x00
 481
 482 #ifdef CONFIG_MAGIC_SYSRQ
 483
 484 static int sysrq_pressed;
 485 static struct sysrq_work sysrq;
 486
 487 static void sclp_vt220_reset_session(void)
 488 {
 489         sysrq_pressed = 0;
 490 }
 491
 492 static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
 493 {
 494         int i;
 495
 496         for (i = 0; i < count; i++) {
 497                 /* Handle magic sys request */
 498                 if (buffer[i] == ('O' ^ 0100)) { /* CTRL-O */
 499                         /*
 500                          * If pressed again, reset sysrq_pressed
 501                          * and flip CTRL-O character
 502                          */
 503                         sysrq_pressed = !sysrq_pressed;
 504                         if (sysrq_pressed)
 505                                 continue;
 506                 } else if (sysrq_pressed) {
 507                         sysrq.key = buffer[i];
 508                         schedule_sysrq_work(&sysrq);
 509                         sysrq_pressed = 0;
 510                         continue;
 511                 }
 512                 tty_insert_flip_char(&sclp_vt220_port, buffer[i], 0);
 513         }
 514 }
 515
 516 #else
 517
 518 static void sclp_vt220_reset_session(void)
 519 {
 520 }
 521
 522 static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
 523 {
 524         tty_insert_flip_string(&sclp_vt220_port, buffer, count);
 525 }
 526
 527 #endif
 528
 529 /*
 530  * Called by the SCLP to report incoming event buffers.
 531  */
 532 static void
 533 sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
 534 {
 535         char *buffer;
 536         unsigned int count;
 537
 538         buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
 539         count = evbuf->length - sizeof(struct evbuf_header);
 540
 541         switch (*buffer) {
 542         case SCLP_VT220_SESSION_ENDED:
 543         case SCLP_VT220_SESSION_STARTED:
 544                 sclp_vt220_reset_session();
 545                 break;
 546         case SCLP_VT220_SESSION_DATA:
 547                 /* Send input to line discipline */
 548                 buffer++;
 549                 count--;
 550                 sclp_vt220_handle_input(buffer, count);
 551                 tty_flip_buffer_push(&sclp_vt220_port);
 552                 break;
 553         }
 554 }
 555
 556 /*
 557  * This routine is called when a particular tty device is opened.
 558  */
 559 static int
 560 sclp_vt220_open(struct tty_struct *tty, struct file *filp)
 561 {
 562         if (tty->count == 1) {
 563                 tty_port_tty_set(&sclp_vt220_port, tty);
 564                 sclp_vt220_port.low_latency = 0;
 565                 if (!tty->winsize.ws_row && !tty->winsize.ws_col) {
 566                         tty->winsize.ws_row = 24;
 567                         tty->winsize.ws_col = 80;
 568                 }
 569         }
 570         return 0;
 571 }
 572
 573 /*
 574  * This routine is called when a particular tty device is closed.
 575  */
 576 static void
 577 sclp_vt220_close(struct tty_struct *tty, struct file *filp)
 578 {
 579         if (tty->count == 1)
 580                 tty_port_tty_set(&sclp_vt220_port, NULL);
 581 }
 582
 583 /*
 584  * This routine is called by the kernel to write a single
 585  * character to the tty device.  If the kernel uses this routine,
 586  * it must call the flush_chars() routine (if defined) when it is
 587  * done stuffing characters into the driver.
 588  */
 589 static int
 590 sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
 591 {
 592         return __sclp_vt220_write(&ch, 1, 0, 0, 1);
 593 }
 594
 595 /*
 596  * This routine is called by the kernel after it has written a
 597  * series of characters to the tty device using put_char().
 598  */
 599 static void
 600 sclp_vt220_flush_chars(struct tty_struct *tty)
 601 {
 602         if (!sclp_vt220_queue_running)
 603                 sclp_vt220_emit_current();
 604         else
 605                 sclp_vt220_flush_later = 1;
 606 }
 607
 608 /*
 609  * This routine returns the numbers of characters the tty driver
 610  * will accept for queuing to be written.  This number is subject
 611  * to change as output buffers get emptied, or if the output flow
 612  * control is acted.
 613  */
 614 static int
 615 sclp_vt220_write_room(struct tty_struct *tty)
 616 {
 617         unsigned long flags;
 618         struct list_head *l;
 619         int count;
 620
 621         spin_lock_irqsave(&sclp_vt220_lock, flags);
 622         count = 0;
 623         if (sclp_vt220_current_request != NULL)
 624                 count = sclp_vt220_space_left(sclp_vt220_current_request);
 625         list_for_each(l, &sclp_vt220_empty)
 626                 count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
 627         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 628         return count;
 629 }
 630
 631 /*
 632  * Return number of buffered chars.
 633  */
 634 static int
 635 sclp_vt220_chars_in_buffer(struct tty_struct *tty)
 636 {
 637         unsigned long flags;
 638         struct list_head *l;
 639         struct sclp_vt220_request *r;
 640         int count;
 641
 642         spin_lock_irqsave(&sclp_vt220_lock, flags);
 643         count = 0;
 644         if (sclp_vt220_current_request != NULL)
 645                 count = sclp_vt220_chars_stored(sclp_vt220_current_request);
 646         list_for_each(l, &sclp_vt220_outqueue) {
 647                 r = list_entry(l, struct sclp_vt220_request, list);
 648                 count += sclp_vt220_chars_stored(r);
 649         }
 650         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 651         return count;
 652 }
 653
 654 /*
 655  * Pass on all buffers to the hardware. Return only when there are no more
 656  * buffers pending.
 657  */
 658 static void
 659 sclp_vt220_flush_buffer(struct tty_struct *tty)
 660 {
 661         sclp_vt220_emit_current();
 662 }
 663
 664 /* Release allocated pages. */
 665 static void __init __sclp_vt220_free_pages(void)
 666 {
 667         struct list_head *page, *p;
 668
 669         list_for_each_safe(page, p, &sclp_vt220_empty) {
 670                 list_del(page);
 671                 free_page((unsigned long) page);
 672         }
 673 }
 674
 675 /* Release memory and unregister from sclp core. Controlled by init counting -
 676  * only the last invoker will actually perform these actions. */
 677 static void __init __sclp_vt220_cleanup(void)
 678 {
 679         sclp_vt220_init_count--;
 680         if (sclp_vt220_init_count != 0)
 681                 return;
 682         sclp_unregister(&sclp_vt220_register);
 683         __sclp_vt220_free_pages();
 684         tty_port_destroy(&sclp_vt220_port);
 685 }
 686
 687 /* Allocate buffer pages and register with sclp core. Controlled by init
 688  * counting - only the first invoker will actually perform these actions. */
 689 static int __init __sclp_vt220_init(int num_pages)
 690 {
 691         void *page;
 692         int i;
 693         int rc;
 694
 695         sclp_vt220_init_count++;
 696         if (sclp_vt220_init_count != 1)
 697                 return 0;
 698         spin_lock_init(&sclp_vt220_lock);
 699         INIT_LIST_HEAD(&sclp_vt220_empty);
 700         INIT_LIST_HEAD(&sclp_vt220_outqueue);
 701         init_timer(&sclp_vt220_timer);
 702         tty_port_init(&sclp_vt220_port);
 703         sclp_vt220_current_request = NULL;
 704         sclp_vt220_buffered_chars = 0;
 705         sclp_vt220_flush_later = 0;
 706
 707         /* Allocate pages for output buffering */
 708         rc = -ENOMEM;
 709         for (i = 0; i < num_pages; i++) {
 710                 page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 711                 if (!page)
 712                         goto out;
 713                 list_add_tail(page, &sclp_vt220_empty);
 714         }
 715         rc = sclp_register(&sclp_vt220_register);
 716 out:
 717         if (rc) {
 718                 __sclp_vt220_free_pages();
 719                 sclp_vt220_init_count--;
 720                 tty_port_destroy(&sclp_vt220_port);
 721         }
 722         return rc;
 723 }
 724
 725 static const struct tty_operations sclp_vt220_ops = {
 726         .open = sclp_vt220_open,
 727         .close = sclp_vt220_close,
 728         .write = sclp_vt220_write,
 729         .put_char = sclp_vt220_put_char,
 730         .flush_chars = sclp_vt220_flush_chars,
 731         .write_room = sclp_vt220_write_room,
 732         .chars_in_buffer = sclp_vt220_chars_in_buffer,
 733         .flush_buffer = sclp_vt220_flush_buffer,
 734 };
 735
 736 /*
 737  * Register driver with SCLP and Linux and initialize internal tty structures.
 738  */
 739 static int __init sclp_vt220_tty_init(void)
 740 {
 741         struct tty_driver *driver;
 742         int rc;
 743
 744         /* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
 745          * symmetry between VM and LPAR systems regarding ttyS1. */
 746         driver = alloc_tty_driver(1);
 747         if (!driver)
 748                 return -ENOMEM;
 749         rc = __sclp_vt220_init(MAX_KMEM_PAGES);
 750         if (rc)
 751                 goto out_driver;
 752
 753         driver->driver_name = SCLP_VT220_DRIVER_NAME;
 754         driver->name = SCLP_VT220_DEVICE_NAME;
 755         driver->major = SCLP_VT220_MAJOR;
 756         driver->minor_start = SCLP_VT220_MINOR;
 757         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 758         driver->subtype = SYSTEM_TYPE_TTY;
 759         driver->init_termios = tty_std_termios;
 760         driver->flags = TTY_DRIVER_REAL_RAW;
 761         tty_set_operations(driver, &sclp_vt220_ops);
 762         tty_port_link_device(&sclp_vt220_port, driver, 0);
 763
 764         rc = tty_register_driver(driver);
 765         if (rc)
 766                 goto out_init;
 767         rc = sclp_register(&sclp_vt220_register_input);
 768         if (rc)
 769                 goto out_reg;
 770         sclp_vt220_driver = driver;
 771         return 0;
 772
 773 out_reg:
 774         tty_unregister_driver(driver);
 775 out_init:
 776         __sclp_vt220_cleanup();
 777 out_driver:
 778         put_tty_driver(driver);
 779         return rc;
 780 }
 781 __initcall(sclp_vt220_tty_init);
 782
 783 static void __sclp_vt220_flush_buffer(void)
 784 {
 785         unsigned long flags;
 786
 787         sclp_vt220_emit_current();
 788         spin_lock_irqsave(&sclp_vt220_lock, flags);
 789         if (timer_pending(&sclp_vt220_timer))
 790                 del_timer(&sclp_vt220_timer);
 791         while (sclp_vt220_queue_running) {
 792                 spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 793                 sclp_sync_wait();
 794                 spin_lock_irqsave(&sclp_vt220_lock, flags);
 795         }
 796         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 797 }
 798
 799 /*
 800  * Resume console: If there are cached messages, emit them.
 801  */
 802 static void sclp_vt220_resume(void)
 803 {
 804         unsigned long flags;
 805
 806         spin_lock_irqsave(&sclp_vt220_lock, flags);
 807         sclp_vt220_suspended = 0;
 808         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 809         sclp_vt220_emit_current();
 810 }
 811
 812 /*
 813  * Suspend console: Set suspend flag and flush console
 814  */
 815 static void sclp_vt220_suspend(void)
 816 {
 817         unsigned long flags;
 818
 819         spin_lock_irqsave(&sclp_vt220_lock, flags);
 820         sclp_vt220_suspended = 1;
 821         spin_unlock_irqrestore(&sclp_vt220_lock, flags);
 822         __sclp_vt220_flush_buffer();
 823 }
 824
 825 static void sclp_vt220_pm_event_fn(struct sclp_register *reg,
 826                                    enum sclp_pm_event sclp_pm_event)
 827 {
 828         switch (sclp_pm_event) {
 829         case SCLP_PM_EVENT_FREEZE:
 830                 sclp_vt220_suspend();
 831                 break;
 832         case SCLP_PM_EVENT_RESTORE:
 833         case SCLP_PM_EVENT_THAW:
 834                 sclp_vt220_resume();
 835                 break;
 836         }
 837 }
 838
 839 #ifdef CONFIG_SCLP_VT220_CONSOLE
 840
 841 static void
 842 sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
 843 {
 844         __sclp_vt220_write((const unsigned char *) buf, count, 1, 1, 0);
 845 }
 846
 847 static struct tty_driver *
 848 sclp_vt220_con_device(struct console *c, int *index)
 849 {
 850         *index = 0;
 851         return sclp_vt220_driver;
 852 }
 853
 854 static int
 855 sclp_vt220_notify(struct notifier_block *self,
 856                           unsigned long event, void *data)
 857 {
 858         __sclp_vt220_flush_buffer();
 859         return NOTIFY_OK;
 860 }
 861
 862 static struct notifier_block on_panic_nb = {
 863         .notifier_call = sclp_vt220_notify,
 864         .priority = 1,
 865 };
 866
 867 static struct notifier_block on_reboot_nb = {
 868         .notifier_call = sclp_vt220_notify,
 869         .priority = 1,
 870 };
 871
 872 /* Structure needed to register with printk */
 873 static struct console sclp_vt220_console =
 874 {
 875         .name = SCLP_VT220_CONSOLE_NAME,
 876         .write = sclp_vt220_con_write,
 877         .device = sclp_vt220_con_device,
 878         .flags = CON_PRINTBUFFER,
 879         .index = SCLP_VT220_CONSOLE_INDEX
 880 };
 881
 882 static int __init
 883 sclp_vt220_con_init(void)
 884 {
 885         int rc;
 886
 887         rc = __sclp_vt220_init(sclp_console_pages);
 888         if (rc)
 889                 return rc;
 890         /* Attach linux console */
 891         atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
 892         register_reboot_notifier(&on_reboot_nb);
 893         register_console(&sclp_vt220_console);
 894         return 0;
 895 }
 896
 897 console_initcall(sclp_vt220_con_init);
 898 #endif /* CONFIG_SCLP_VT220_CONSOLE */
 899