drivers/s390/char/sclp_tty.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *    SCLP line mode terminal driver.
   4  *
   5  *  S390 version
   6  *    Copyright IBM Corp. 1999
   7  *    Author(s): Martin Peschke <[email protected]>
   8  *               Martin Schwidefsky <[email protected]>
   9  */
  10
  11 #include <linux/kmod.h>
  12 #include <linux/tty.h>
  13 #include <linux/tty_driver.h>
  14 #include <linux/tty_flip.h>
  15 #include <linux/err.h>
  16 #include <linux/init.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/gfp.h>
  19 #include <linux/uaccess.h>
  20
  21 #include "ctrlchar.h"
  22 #include "sclp.h"
  23 #include "sclp_rw.h"
  24 #include "sclp_tty.h"
  25
  26 /*
  27  * size of a buffer that collects single characters coming in
  28  * via sclp_tty_put_char()
  29  */
  30 #define SCLP_TTY_BUF_SIZE 512
  31
  32 /*
  33  * There is exactly one SCLP terminal, so we can keep things simple
  34  * and allocate all variables statically.
  35  */
  36
  37 /* Lock to guard over changes to global variables. */
  38 static DEFINE_SPINLOCK(sclp_tty_lock);
  39 /* List of free pages that can be used for console output buffering. */
  40 static LIST_HEAD(sclp_tty_pages);
  41 /* List of full struct sclp_buffer structures ready for output. */
  42 static LIST_HEAD(sclp_tty_outqueue);
  43 /* Counter how many buffers are emitted. */
  44 static int sclp_tty_buffer_count;
  45 /* Pointer to current console buffer. */
  46 static struct sclp_buffer *sclp_ttybuf;
  47 /* Timer for delayed output of console messages. */
  48 static struct timer_list sclp_tty_timer;
  49
  50 static struct tty_port sclp_port;
  51 static unsigned char sclp_tty_chars[SCLP_TTY_BUF_SIZE];
  52 static unsigned short int sclp_tty_chars_count;
  53
  54 struct tty_driver *sclp_tty_driver;
  55
  56 static int sclp_tty_tolower;
  57
  58 #define SCLP_TTY_COLUMNS 320
  59 #define SPACES_PER_TAB 8
  60 #define CASE_DELIMITER 0x6c /* to separate upper and lower case (% in EBCDIC) */
  61
  62 /* This routine is called whenever we try to open a SCLP terminal. */
  63 static int
  64 sclp_tty_open(struct tty_struct *tty, struct file *filp)
  65 {
  66         tty_port_tty_set(&sclp_port, tty);
  67         tty->driver_data = NULL;
  68         return 0;
  69 }
  70
  71 /* This routine is called when the SCLP terminal is closed. */
  72 static void
  73 sclp_tty_close(struct tty_struct *tty, struct file *filp)
  74 {
  75         if (tty->count > 1)
  76                 return;
  77         tty_port_tty_set(&sclp_port, NULL);
  78 }
  79
  80 /*
  81  * This routine returns the numbers of characters the tty driver
  82  * will accept for queuing to be written.  This number is subject
  83  * to change as output buffers get emptied, or if the output flow
  84  * control is acted. This is not an exact number because not every
  85  * character needs the same space in the sccb. The worst case is
  86  * a string of newlines. Every newline creates a new message which
  87  * needs 82 bytes.
  88  */
  89 static int
  90 sclp_tty_write_room (struct tty_struct *tty)
  91 {
  92         unsigned long flags;
  93         struct list_head *l;
  94         int count;
  95
  96         spin_lock_irqsave(&sclp_tty_lock, flags);
  97         count = 0;
  98         if (sclp_ttybuf != NULL)
  99                 count = sclp_buffer_space(sclp_ttybuf) / sizeof(struct msg_buf);
 100         list_for_each(l, &sclp_tty_pages)
 101                 count += NR_EMPTY_MSG_PER_SCCB;
 102         spin_unlock_irqrestore(&sclp_tty_lock, flags);
 103         return count;
 104 }
 105
 106 static void
 107 sclp_ttybuf_callback(struct sclp_buffer *buffer, int rc)
 108 {
 109         unsigned long flags;
 110         void *page;
 111
 112         do {
 113                 page = sclp_unmake_buffer(buffer);
 114                 spin_lock_irqsave(&sclp_tty_lock, flags);
 115                 /* Remove buffer from outqueue */
 116                 list_del(&buffer->list);
 117                 sclp_tty_buffer_count--;
 118                 list_add_tail((struct list_head *) page, &sclp_tty_pages);
 119                 /* Check if there is a pending buffer on the out queue. */
 120                 buffer = NULL;
 121                 if (!list_empty(&sclp_tty_outqueue))
 122                         buffer = list_entry(sclp_tty_outqueue.next,
 123                                             struct sclp_buffer, list);
 124                 spin_unlock_irqrestore(&sclp_tty_lock, flags);
 125         } while (buffer && sclp_emit_buffer(buffer, sclp_ttybuf_callback));
 126
 127         tty_port_tty_wakeup(&sclp_port);
 128 }
 129
 130 static inline void
 131 __sclp_ttybuf_emit(struct sclp_buffer *buffer)
 132 {
 133         unsigned long flags;
 134         int count;
 135         int rc;
 136
 137         spin_lock_irqsave(&sclp_tty_lock, flags);
 138         list_add_tail(&buffer->list, &sclp_tty_outqueue);
 139         count = sclp_tty_buffer_count++;
 140         spin_unlock_irqrestore(&sclp_tty_lock, flags);
 141         if (count)
 142                 return;
 143         rc = sclp_emit_buffer(buffer, sclp_ttybuf_callback);
 144         if (rc)
 145                 sclp_ttybuf_callback(buffer, rc);
 146 }
 147
 148 /*
 149  * When this routine is called from the timer then we flush the
 150  * temporary write buffer.
 151  */
 152 static void
 153 sclp_tty_timeout(struct timer_list *unused)
 154 {
 155         unsigned long flags;
 156         struct sclp_buffer *buf;
 157
 158         spin_lock_irqsave(&sclp_tty_lock, flags);
 159         buf = sclp_ttybuf;
 160         sclp_ttybuf = NULL;
 161         spin_unlock_irqrestore(&sclp_tty_lock, flags);
 162
 163         if (buf != NULL) {
 164                 __sclp_ttybuf_emit(buf);
 165         }
 166 }
 167
 168 /*
 169  * Write a string to the sclp tty.
 170  */
 171 static int sclp_tty_write_string(const unsigned char *str, int count, int may_fail)
 172 {
 173         unsigned long flags;
 174         void *page;
 175         int written;
 176         int overall_written;
 177         struct sclp_buffer *buf;
 178
 179         if (count <= 0)
 180                 return 0;
 181         overall_written = 0;
 182         spin_lock_irqsave(&sclp_tty_lock, flags);
 183         do {
 184                 /* Create a sclp output buffer if none exists yet */
 185                 if (sclp_ttybuf == NULL) {
 186                         while (list_empty(&sclp_tty_pages)) {
 187                                 spin_unlock_irqrestore(&sclp_tty_lock, flags);
 188                                 if (may_fail)
 189                                         goto out;
 190                                 else
 191                                         sclp_sync_wait();
 192                                 spin_lock_irqsave(&sclp_tty_lock, flags);
 193                         }
 194                         page = sclp_tty_pages.next;
 195                         list_del((struct list_head *) page);
 196                         sclp_ttybuf = sclp_make_buffer(page, SCLP_TTY_COLUMNS,
 197                                                        SPACES_PER_TAB);
 198                 }
 199                 /* try to write the string to the current output buffer */
 200                 written = sclp_write(sclp_ttybuf, str, count);
 201                 overall_written += written;
 202                 if (written == count)
 203                         break;
 204                 /*
 205                  * Not all characters could be written to the current
 206                  * output buffer. Emit the buffer, create a new buffer
 207                  * and then output the rest of the string.
 208                  */
 209                 buf = sclp_ttybuf;
 210                 sclp_ttybuf = NULL;
 211                 spin_unlock_irqrestore(&sclp_tty_lock, flags);
 212                 __sclp_ttybuf_emit(buf);
 213                 spin_lock_irqsave(&sclp_tty_lock, flags);
 214                 str += written;
 215                 count -= written;
 216         } while (count > 0);
 217         /* Setup timer to output current console buffer after 1/10 second */
 218         if (sclp_ttybuf && sclp_chars_in_buffer(sclp_ttybuf) &&
 219             !timer_pending(&sclp_tty_timer)) {
 220                 mod_timer(&sclp_tty_timer, jiffies + HZ / 10);
 221         }
 222         spin_unlock_irqrestore(&sclp_tty_lock, flags);
 223 out:
 224         return overall_written;
 225 }
 226
 227 /*
 228  * This routine is called by the kernel to write a series of characters to the
 229  * tty device. The characters may come from user space or kernel space. This
 230  * routine will return the number of characters actually accepted for writing.
 231  */
 232 static int
 233 sclp_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
 234 {
 235         if (sclp_tty_chars_count > 0) {
 236                 sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
 237                 sclp_tty_chars_count = 0;
 238         }
 239         return sclp_tty_write_string(buf, count, 1);
 240 }
 241
 242 /*
 243  * This routine is called by the kernel to write a single character to the tty
 244  * device. If the kernel uses this routine, it must call the flush_chars()
 245  * routine (if defined) when it is done stuffing characters into the driver.
 246  *
 247  * Characters provided to sclp_tty_put_char() are buffered by the SCLP driver.
 248  * If the given character is a '\n' the contents of the SCLP write buffer
 249  * - including previous characters from sclp_tty_put_char() and strings from
 250  * sclp_write() without final '\n' - will be written.
 251  */
 252 static int
 253 sclp_tty_put_char(struct tty_struct *tty, unsigned char ch)
 254 {
 255         sclp_tty_chars[sclp_tty_chars_count++] = ch;
 256         if (ch == '\n' || sclp_tty_chars_count >= SCLP_TTY_BUF_SIZE) {
 257                 sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
 258                 sclp_tty_chars_count = 0;
 259         }
 260         return 1;
 261 }
 262
 263 /*
 264  * This routine is called by the kernel after it has written a series of
 265  * characters to the tty device using put_char().
 266  */
 267 static void
 268 sclp_tty_flush_chars(struct tty_struct *tty)
 269 {
 270         if (sclp_tty_chars_count > 0) {
 271                 sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
 272                 sclp_tty_chars_count = 0;
 273         }
 274 }
 275
 276 /*
 277  * This routine returns the number of characters in the write buffer of the
 278  * SCLP driver. The provided number includes all characters that are stored
 279  * in the SCCB (will be written next time the SCLP is not busy) as well as
 280  * characters in the write buffer (will not be written as long as there is a
 281  * final line feed missing).
 282  */
 283 static int
 284 sclp_tty_chars_in_buffer(struct tty_struct *tty)
 285 {
 286         unsigned long flags;
 287         struct list_head *l;
 288         struct sclp_buffer *t;
 289         int count;
 290
 291         spin_lock_irqsave(&sclp_tty_lock, flags);
 292         count = 0;
 293         if (sclp_ttybuf != NULL)
 294                 count = sclp_chars_in_buffer(sclp_ttybuf);
 295         list_for_each(l, &sclp_tty_outqueue) {
 296                 t = list_entry(l, struct sclp_buffer, list);
 297                 count += sclp_chars_in_buffer(t);
 298         }
 299         spin_unlock_irqrestore(&sclp_tty_lock, flags);
 300         return count;
 301 }
 302
 303 /*
 304  * removes all content from buffers of low level driver
 305  */
 306 static void
 307 sclp_tty_flush_buffer(struct tty_struct *tty)
 308 {
 309         if (sclp_tty_chars_count > 0) {
 310                 sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
 311                 sclp_tty_chars_count = 0;
 312         }
 313 }
 314
 315 /*
 316  * push input to tty
 317  */
 318 static void
 319 sclp_tty_input(unsigned char* buf, unsigned int count)
 320 {
 321         struct tty_struct *tty = tty_port_tty_get(&sclp_port);
 322         unsigned int cchar;
 323
 324         /*
 325          * If this tty driver is currently closed
 326          * then throw the received input away.
 327          */
 328         if (tty == NULL)
 329                 return;
 330         cchar = ctrlchar_handle(buf, count, tty);
 331         switch (cchar & CTRLCHAR_MASK) {
 332         case CTRLCHAR_SYSRQ:
 333                 break;
 334         case CTRLCHAR_CTRL:
 335                 tty_insert_flip_char(&sclp_port, cchar, TTY_NORMAL);
 336                 tty_flip_buffer_push(&sclp_port);
 337                 break;
 338         case CTRLCHAR_NONE:
 339                 /* send (normal) input to line discipline */
 340                 if (count < 2 ||
 341                     (strncmp((const char *) buf + count - 2, "^n", 2) &&
 342                      strncmp((const char *) buf + count - 2, "\252n", 2))) {
 343                         /* add the auto \n */
 344                         tty_insert_flip_string(&sclp_port, buf, count);
 345                         tty_insert_flip_char(&sclp_port, '\n', TTY_NORMAL);
 346                 } else
 347                         tty_insert_flip_string(&sclp_port, buf, count - 2);
 348                 tty_flip_buffer_push(&sclp_port);
 349                 break;
 350         }
 351         tty_kref_put(tty);
 352 }
 353
 354 /*
 355  * get a EBCDIC string in upper/lower case,
 356  * find out characters in lower/upper case separated by a special character,
 357  * modifiy original string,
 358  * returns length of resulting string
 359  */
 360 static int sclp_switch_cases(unsigned char *buf, int count)
 361 {
 362         unsigned char *ip, *op;
 363         int toggle;
 364
 365         /* initially changing case is off */
 366         toggle = 0;
 367         ip = op = buf;
 368         while (count-- > 0) {
 369                 /* compare with special character */
 370                 if (*ip == CASE_DELIMITER) {
 371                         /* followed by another special character? */
 372                         if (count && ip[1] == CASE_DELIMITER) {
 373                                 /*
 374                                  * ... then put a single copy of the special
 375                                  * character to the output string
 376                                  */
 377                                 *op++ = *ip++;
 378                                 count--;
 379                         } else
 380                                 /*
 381                                  * ... special character follower by a normal
 382                                  * character toggles the case change behaviour
 383                                  */
 384                                 toggle = ~toggle;
 385                         /* skip special character */
 386                         ip++;
 387                 } else
 388                         /* not the special character */
 389                         if (toggle)
 390                                 /* but case switching is on */
 391                                 if (sclp_tty_tolower)
 392                                         /* switch to uppercase */
 393                                         *op++ = _ebc_toupper[(int) *ip++];
 394                                 else
 395                                         /* switch to lowercase */
 396                                         *op++ = _ebc_tolower[(int) *ip++];
 397                         else
 398                                 /* no case switching, copy the character */
 399                                 *op++ = *ip++;
 400         }
 401         /* return length of reformatted string. */
 402         return op - buf;
 403 }
 404
 405 static void sclp_get_input(struct gds_subvector *sv)
 406 {
 407         unsigned char *str;
 408         int count;
 409
 410         str = (unsigned char *) (sv + 1);
 411         count = sv->length - sizeof(*sv);
 412         if (sclp_tty_tolower)
 413                 EBC_TOLOWER(str, count);
 414         count = sclp_switch_cases(str, count);
 415         /* convert EBCDIC to ASCII (modify original input in SCCB) */
 416         sclp_ebcasc_str(str, count);
 417
 418         /* transfer input to high level driver */
 419         sclp_tty_input(str, count);
 420 }
 421
 422 static inline void sclp_eval_selfdeftextmsg(struct gds_subvector *sv)
 423 {
 424         void *end;
 425
 426         end = (void *) sv + sv->length;
 427         for (sv = sv + 1; (void *) sv < end; sv = (void *) sv + sv->length)
 428                 if (sv->key == 0x30)
 429                         sclp_get_input(sv);
 430 }
 431
 432 static inline void sclp_eval_textcmd(struct gds_vector *v)
 433 {
 434         struct gds_subvector *sv;
 435         void *end;
 436
 437         end = (void *) v + v->length;
 438         for (sv = (struct gds_subvector *) (v + 1);
 439              (void *) sv < end; sv = (void *) sv + sv->length)
 440                 if (sv->key == GDS_KEY_SELFDEFTEXTMSG)
 441                         sclp_eval_selfdeftextmsg(sv);
 442
 443 }
 444
 445 static inline void sclp_eval_cpmsu(struct gds_vector *v)
 446 {
 447         void *end;
 448
 449         end = (void *) v + v->length;
 450         for (v = v + 1; (void *) v < end; v = (void *) v + v->length)
 451                 if (v->gds_id == GDS_ID_TEXTCMD)
 452                         sclp_eval_textcmd(v);
 453 }
 454
 455
 456 static inline void sclp_eval_mdsmu(struct gds_vector *v)
 457 {
 458         v = sclp_find_gds_vector(v + 1, (void *) v + v->length, GDS_ID_CPMSU);
 459         if (v)
 460                 sclp_eval_cpmsu(v);
 461 }
 462
 463 static void sclp_tty_receiver(struct evbuf_header *evbuf)
 464 {
 465         struct gds_vector *v;
 466
 467         v = sclp_find_gds_vector(evbuf + 1, (void *) evbuf + evbuf->length,
 468                                  GDS_ID_MDSMU);
 469         if (v)
 470                 sclp_eval_mdsmu(v);
 471 }
 472
 473 static void
 474 sclp_tty_state_change(struct sclp_register *reg)
 475 {
 476 }
 477
 478 static struct sclp_register sclp_input_event =
 479 {
 480         .receive_mask = EVTYP_OPCMD_MASK | EVTYP_PMSGCMD_MASK,
 481         .state_change_fn = sclp_tty_state_change,
 482         .receiver_fn = sclp_tty_receiver
 483 };
 484
 485 static const struct tty_operations sclp_ops = {
 486         .open = sclp_tty_open,
 487         .close = sclp_tty_close,
 488         .write = sclp_tty_write,
 489         .put_char = sclp_tty_put_char,
 490         .flush_chars = sclp_tty_flush_chars,
 491         .write_room = sclp_tty_write_room,
 492         .chars_in_buffer = sclp_tty_chars_in_buffer,
 493         .flush_buffer = sclp_tty_flush_buffer,
 494 };
 495
 496 static int __init
 497 sclp_tty_init(void)
 498 {
 499         struct tty_driver *driver;
 500         void *page;
 501         int i;
 502         int rc;
 503
 504         /* z/VM multiplexes the line mode output on the 32xx screen */
 505         if (MACHINE_IS_VM && !CONSOLE_IS_SCLP)
 506                 return 0;
 507         if (!sclp.has_linemode)
 508                 return 0;
 509         driver = alloc_tty_driver(1);
 510         if (!driver)
 511                 return -ENOMEM;
 512
 513         rc = sclp_rw_init();
 514         if (rc) {
 515                 put_tty_driver(driver);
 516                 return rc;
 517         }
 518         /* Allocate pages for output buffering */
 519         for (i = 0; i < MAX_KMEM_PAGES; i++) {
 520                 page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 521                 if (page == NULL) {
 522                         put_tty_driver(driver);
 523                         return -ENOMEM;
 524                 }
 525                 list_add_tail((struct list_head *) page, &sclp_tty_pages);
 526         }
 527         timer_setup(&sclp_tty_timer, sclp_tty_timeout, 0);
 528         sclp_ttybuf = NULL;
 529         sclp_tty_buffer_count = 0;
 530         if (MACHINE_IS_VM) {
 531                 /* case input lines to lowercase */
 532                 sclp_tty_tolower = 1;
 533         }
 534         sclp_tty_chars_count = 0;
 535
 536         rc = sclp_register(&sclp_input_event);
 537         if (rc) {
 538                 put_tty_driver(driver);
 539                 return rc;
 540         }
 541
 542         tty_port_init(&sclp_port);
 543
 544         driver->driver_name = "sclp_line";
 545         driver->name = "sclp_line";
 546         driver->major = TTY_MAJOR;
 547         driver->minor_start = 64;
 548         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 549         driver->subtype = SYSTEM_TYPE_TTY;
 550         driver->init_termios = tty_std_termios;
 551         driver->init_termios.c_iflag = IGNBRK | IGNPAR;
 552         driver->init_termios.c_oflag = ONLCR;
 553         driver->init_termios.c_lflag = ISIG | ECHO;
 554         driver->flags = TTY_DRIVER_REAL_RAW;
 555         tty_set_operations(driver, &sclp_ops);
 556         tty_port_link_device(&sclp_port, driver, 0);
 557         rc = tty_register_driver(driver);
 558         if (rc) {
 559                 put_tty_driver(driver);
 560                 tty_port_destroy(&sclp_port);
 561                 return rc;
 562         }
 563         sclp_tty_driver = driver;
 564         return 0;
 565 }
 566 device_initcall(sclp_tty_init);