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 <mpeschke@de.ibm.com>
   8  *               Martin Schwidefsky <schwidefsky@de.ibm.com>
   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 spinlock_t sclp_tty_lock;
  39 /* List of free pages that can be used for console output buffering. */
  40 static struct list_head sclp_tty_pages;
  41 /* List of full struct sclp_buffer structures ready for output. */
  42 static struct 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 static int sclp_tty_columns = 80;
  58
  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         sclp_port.low_latency = 0;
  69         return 0;
  70 }
  71
  72 /* This routine is called when the SCLP terminal is closed. */
  73 static void
  74 sclp_tty_close(struct tty_struct *tty, struct file *filp)
  75 {
  76         if (tty->count > 1)
  77                 return;
  78         tty_port_tty_set(&sclp_port, NULL);
  79 }
  80
  81 /*
  82  * This routine returns the numbers of characters the tty driver
  83  * will accept for queuing to be written.  This number is subject
  84  * to change as output buffers get emptied, or if the output flow
  85  * control is acted. This is not an exact number because not every
  86  * character needs the same space in the sccb. The worst case is
  87  * a string of newlines. Every newline creates a new message which
  88  * needs 82 bytes.
  89  */
  90 static int
  91 sclp_tty_write_room (struct tty_struct *tty)
  92 {
  93         unsigned long flags;
  94         struct list_head *l;
  95         int count;
  96
  97         spin_lock_irqsave(&sclp_tty_lock, flags);
  98         count = 0;
  99         if (sclp_ttybuf != NULL)
 100                 count = sclp_buffer_space(sclp_ttybuf) / sizeof(struct msg_buf);
 101         list_for_each(l, &sclp_tty_pages)
 102                 count += NR_EMPTY_MSG_PER_SCCB;
 103         spin_unlock_irqrestore(&sclp_tty_lock, flags);
 104         return count;
 105 }
 106
 107 static void
 108 sclp_ttybuf_callback(struct sclp_buffer *buffer, int rc)
 109 {
 110         unsigned long flags;
 111         void *page;
 112
 113         do {
 114                 page = sclp_unmake_buffer(buffer);
 115                 spin_lock_irqsave(&sclp_tty_lock, flags);
 116                 /* Remove buffer from outqueue */
 117                 list_del(&buffer->list);
 118                 sclp_tty_buffer_count--;
 119                 list_add_tail((struct list_head *) page, &sclp_tty_pages);
 120                 /* Check if there is a pending buffer on the out queue. */
 121                 buffer = NULL;
 122                 if (!list_empty(&sclp_tty_outqueue))
 123                         buffer = list_entry(sclp_tty_outqueue.next,
 124                                             struct sclp_buffer, list);
 125                 spin_unlock_irqrestore(&sclp_tty_lock, flags);
 126         } while (buffer && sclp_emit_buffer(buffer, sclp_ttybuf_callback));
 127
 128         tty_port_tty_wakeup(&sclp_port);
 129 }
 130
 131 static inline void
 132 __sclp_ttybuf_emit(struct sclp_buffer *buffer)
 133 {
 134         unsigned long flags;
 135         int count;
 136         int rc;
 137
 138         spin_lock_irqsave(&sclp_tty_lock, flags);
 139         list_add_tail(&buffer->list, &sclp_tty_outqueue);
 140         count = sclp_tty_buffer_count++;
 141         spin_unlock_irqrestore(&sclp_tty_lock, flags);
 142         if (count)
 143                 return;
 144         rc = sclp_emit_buffer(buffer, sclp_ttybuf_callback);
 145         if (rc)
 146                 sclp_ttybuf_callback(buffer, rc);
 147 }
 148
 149 /*
 150  * When this routine is called from the timer then we flush the
 151  * temporary write buffer.
 152  */
 153 static void
 154 sclp_tty_timeout(struct timer_list *unused)
 155 {
 156         unsigned long flags;
 157         struct sclp_buffer *buf;
 158
 159         spin_lock_irqsave(&sclp_tty_lock, flags);
 160         buf = sclp_ttybuf;
 161         sclp_ttybuf = NULL;
 162         spin_unlock_irqrestore(&sclp_tty_lock, flags);
 163
 164         if (buf != NULL) {
 165                 __sclp_ttybuf_emit(buf);
 166         }
 167 }
 168
 169 /*
 170  * Write a string to the sclp tty.
 171  */
 172 static int sclp_tty_write_string(const unsigned char *str, int count, int may_fail)
 173 {
 174         unsigned long flags;
 175         void *page;
 176         int written;
 177         int overall_written;
 178         struct sclp_buffer *buf;
 179
 180         if (count <= 0)
 181                 return 0;
 182         overall_written = 0;
 183         spin_lock_irqsave(&sclp_tty_lock, flags);
 184         do {
 185                 /* Create a sclp output buffer if none exists yet */
 186                 if (sclp_ttybuf == NULL) {
 187                         while (list_empty(&sclp_tty_pages)) {
 188                                 spin_unlock_irqrestore(&sclp_tty_lock, flags);
 189                                 if (may_fail)
 190                                         goto out;
 191                                 else
 192                                         sclp_sync_wait();
 193                                 spin_lock_irqsave(&sclp_tty_lock, flags);
 194                         }
 195                         page = sclp_tty_pages.next;
 196                         list_del((struct list_head *) page);
 197                         sclp_ttybuf = sclp_make_buffer(page, sclp_tty_columns,
 198                                                        SPACES_PER_TAB);
 199                 }
 200                 /* try to write the string to the current output buffer */
 201                 written = sclp_write(sclp_ttybuf, str, count);
 202                 overall_written += written;
 203                 if (written == count)
 204                         break;
 205                 /*
 206                  * Not all characters could be written to the current
 207                  * output buffer. Emit the buffer, create a new buffer
 208                  * and then output the rest of the string.
 209                  */
 210                 buf = sclp_ttybuf;
 211                 sclp_ttybuf = NULL;
 212                 spin_unlock_irqrestore(&sclp_tty_lock, flags);
 213                 __sclp_ttybuf_emit(buf);
 214                 spin_lock_irqsave(&sclp_tty_lock, flags);
 215                 str += written;
 216                 count -= written;
 217         } while (count > 0);
 218         /* Setup timer to output current console buffer after 1/10 second */
 219         if (sclp_ttybuf && sclp_chars_in_buffer(sclp_ttybuf) &&
 220             !timer_pending(&sclp_tty_timer)) {
 221                 mod_timer(&sclp_tty_timer, jiffies + HZ / 10);
 222         }
 223         spin_unlock_irqrestore(&sclp_tty_lock, flags);
 224 out:
 225         return overall_written;
 226 }
 227
 228 /*
 229  * This routine is called by the kernel to write a series of characters to the
 230  * tty device. The characters may come from user space or kernel space. This
 231  * routine will return the number of characters actually accepted for writing.
 232  */
 233 static int
 234 sclp_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
 235 {
 236         if (sclp_tty_chars_count > 0) {
 237                 sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
 238                 sclp_tty_chars_count = 0;
 239         }
 240         return sclp_tty_write_string(buf, count, 1);
 241 }
 242
 243 /*
 244  * This routine is called by the kernel to write a single character to the tty
 245  * device. If the kernel uses this routine, it must call the flush_chars()
 246  * routine (if defined) when it is done stuffing characters into the driver.
 247  *
 248  * Characters provided to sclp_tty_put_char() are buffered by the SCLP driver.
 249  * If the given character is a '\n' the contents of the SCLP write buffer
 250  * - including previous characters from sclp_tty_put_char() and strings from
 251  * sclp_write() without final '\n' - will be written.
 252  */
 253 static int
 254 sclp_tty_put_char(struct tty_struct *tty, unsigned char ch)
 255 {
 256         sclp_tty_chars[sclp_tty_chars_count++] = ch;
 257         if (ch == '\n' || sclp_tty_chars_count >= SCLP_TTY_BUF_SIZE) {
 258                 sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
 259                 sclp_tty_chars_count = 0;
 260         }
 261         return 1;
 262 }
 263
 264 /*
 265  * This routine is called by the kernel after it has written a series of
 266  * characters to the tty device using put_char().
 267  */
 268 static void
 269 sclp_tty_flush_chars(struct tty_struct *tty)
 270 {
 271         if (sclp_tty_chars_count > 0) {
 272                 sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
 273                 sclp_tty_chars_count = 0;
 274         }
 275 }
 276
 277 /*
 278  * This routine returns the number of characters in the write buffer of the
 279  * SCLP driver. The provided number includes all characters that are stored
 280  * in the SCCB (will be written next time the SCLP is not busy) as well as
 281  * characters in the write buffer (will not be written as long as there is a
 282  * final line feed missing).
 283  */
 284 static int
 285 sclp_tty_chars_in_buffer(struct tty_struct *tty)
 286 {
 287         unsigned long flags;
 288         struct list_head *l;
 289         struct sclp_buffer *t;
 290         int count;
 291
 292         spin_lock_irqsave(&sclp_tty_lock, flags);
 293         count = 0;
 294         if (sclp_ttybuf != NULL)
 295                 count = sclp_chars_in_buffer(sclp_ttybuf);
 296         list_for_each(l, &sclp_tty_outqueue) {
 297                 t = list_entry(l, struct sclp_buffer, list);
 298                 count += sclp_chars_in_buffer(t);
 299         }
 300         spin_unlock_irqrestore(&sclp_tty_lock, flags);
 301         return count;
 302 }
 303
 304 /*
 305  * removes all content from buffers of low level driver
 306  */
 307 static void
 308 sclp_tty_flush_buffer(struct tty_struct *tty)
 309 {
 310         if (sclp_tty_chars_count > 0) {
 311                 sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
 312                 sclp_tty_chars_count = 0;
 313         }
 314 }
 315
 316 /*
 317  * push input to tty
 318  */
 319 static void
 320 sclp_tty_input(unsigned char* buf, unsigned int count)
 321 {
 322         struct tty_struct *tty = tty_port_tty_get(&sclp_port);
 323         unsigned int cchar;
 324
 325         /*
 326          * If this tty driver is currently closed
 327          * then throw the received input away.
 328          */
 329         if (tty == NULL)
 330                 return;
 331         cchar = ctrlchar_handle(buf, count, tty);
 332         switch (cchar & CTRLCHAR_MASK) {
 333         case CTRLCHAR_SYSRQ:
 334                 break;
 335         case CTRLCHAR_CTRL:
 336                 tty_insert_flip_char(&sclp_port, cchar, TTY_NORMAL);
 337                 tty_flip_buffer_push(&sclp_port);
 338                 break;
 339         case CTRLCHAR_NONE:
 340                 /* send (normal) input to line discipline */
 341                 if (count < 2 ||
 342                     (strncmp((const char *) buf + count - 2, "^n", 2) &&
 343                      strncmp((const char *) buf + count - 2, "\252n", 2))) {
 344                         /* add the auto \n */
 345                         tty_insert_flip_string(&sclp_port, buf, count);
 346                         tty_insert_flip_char(&sclp_port, '\n', TTY_NORMAL);
 347                 } else
 348                         tty_insert_flip_string(&sclp_port, buf, count - 2);
 349                 tty_flip_buffer_push(&sclp_port);
 350                 break;
 351         }
 352         tty_kref_put(tty);
 353 }
 354
 355 /*
 356  * get a EBCDIC string in upper/lower case,
 357  * find out characters in lower/upper case separated by a special character,
 358  * modifiy original string,
 359  * returns length of resulting string
 360  */
 361 static int sclp_switch_cases(unsigned char *buf, int count)
 362 {
 363         unsigned char *ip, *op;
 364         int toggle;
 365
 366         /* initially changing case is off */
 367         toggle = 0;
 368         ip = op = buf;
 369         while (count-- > 0) {
 370                 /* compare with special character */
 371                 if (*ip == CASE_DELIMITER) {
 372                         /* followed by another special character? */
 373                         if (count && ip[1] == CASE_DELIMITER) {
 374                                 /*
 375                                  * ... then put a single copy of the special
 376                                  * character to the output string
 377                                  */
 378                                 *op++ = *ip++;
 379                                 count--;
 380                         } else
 381                                 /*
 382                                  * ... special character follower by a normal
 383                                  * character toggles the case change behaviour
 384                                  */
 385                                 toggle = ~toggle;
 386                         /* skip special character */
 387                         ip++;
 388                 } else
 389                         /* not the special character */
 390                         if (toggle)
 391                                 /* but case switching is on */
 392                                 if (sclp_tty_tolower)
 393                                         /* switch to uppercase */
 394                                         *op++ = _ebc_toupper[(int) *ip++];
 395                                 else
 396                                         /* switch to lowercase */
 397                                         *op++ = _ebc_tolower[(int) *ip++];
 398                         else
 399                                 /* no case switching, copy the character */
 400                                 *op++ = *ip++;
 401         }
 402         /* return length of reformatted string. */
 403         return op - buf;
 404 }
 405
 406 static void sclp_get_input(struct gds_subvector *sv)
 407 {
 408         unsigned char *str;
 409         int count;
 410
 411         str = (unsigned char *) (sv + 1);
 412         count = sv->length - sizeof(*sv);
 413         if (sclp_tty_tolower)
 414                 EBC_TOLOWER(str, count);
 415         count = sclp_switch_cases(str, count);
 416         /* convert EBCDIC to ASCII (modify original input in SCCB) */
 417         sclp_ebcasc_str(str, count);
 418
 419         /* transfer input to high level driver */
 420         sclp_tty_input(str, count);
 421 }
 422
 423 static inline void sclp_eval_selfdeftextmsg(struct gds_subvector *sv)
 424 {
 425         void *end;
 426
 427         end = (void *) sv + sv->length;
 428         for (sv = sv + 1; (void *) sv < end; sv = (void *) sv + sv->length)
 429                 if (sv->key == 0x30)
 430                         sclp_get_input(sv);
 431 }
 432
 433 static inline void sclp_eval_textcmd(struct gds_vector *v)
 434 {
 435         struct gds_subvector *sv;
 436         void *end;
 437
 438         end = (void *) v + v->length;
 439         for (sv = (struct gds_subvector *) (v + 1);
 440              (void *) sv < end; sv = (void *) sv + sv->length)
 441                 if (sv->key == GDS_KEY_SELFDEFTEXTMSG)
 442                         sclp_eval_selfdeftextmsg(sv);
 443
 444 }
 445
 446 static inline void sclp_eval_cpmsu(struct gds_vector *v)
 447 {
 448         void *end;
 449
 450         end = (void *) v + v->length;
 451         for (v = v + 1; (void *) v < end; v = (void *) v + v->length)
 452                 if (v->gds_id == GDS_ID_TEXTCMD)
 453                         sclp_eval_textcmd(v);
 454 }
 455
 456
 457 static inline void sclp_eval_mdsmu(struct gds_vector *v)
 458 {
 459         v = sclp_find_gds_vector(v + 1, (void *) v + v->length, GDS_ID_CPMSU);
 460         if (v)
 461                 sclp_eval_cpmsu(v);
 462 }
 463
 464 static void sclp_tty_receiver(struct evbuf_header *evbuf)
 465 {
 466         struct gds_vector *v;
 467
 468         v = sclp_find_gds_vector(evbuf + 1, (void *) evbuf + evbuf->length,
 469                                  GDS_ID_MDSMU);
 470         if (v)
 471                 sclp_eval_mdsmu(v);
 472 }
 473
 474 static void
 475 sclp_tty_state_change(struct sclp_register *reg)
 476 {
 477 }
 478
 479 static struct sclp_register sclp_input_event =
 480 {
 481         .receive_mask = EVTYP_OPCMD_MASK | EVTYP_PMSGCMD_MASK,
 482         .state_change_fn = sclp_tty_state_change,
 483         .receiver_fn = sclp_tty_receiver
 484 };
 485
 486 static const struct tty_operations sclp_ops = {
 487         .open = sclp_tty_open,
 488         .close = sclp_tty_close,
 489         .write = sclp_tty_write,
 490         .put_char = sclp_tty_put_char,
 491         .flush_chars = sclp_tty_flush_chars,
 492         .write_room = sclp_tty_write_room,
 493         .chars_in_buffer = sclp_tty_chars_in_buffer,
 494         .flush_buffer = sclp_tty_flush_buffer,
 495 };
 496
 497 static int __init
 498 sclp_tty_init(void)
 499 {
 500         struct tty_driver *driver;
 501         void *page;
 502         int i;
 503         int rc;
 504
 505         /* z/VM multiplexes the line mode output on the 32xx screen */
 506         if (MACHINE_IS_VM && !CONSOLE_IS_SCLP)
 507                 return 0;
 508         if (!sclp.has_linemode)
 509                 return 0;
 510         driver = alloc_tty_driver(1);
 511         if (!driver)
 512                 return -ENOMEM;
 513
 514         rc = sclp_rw_init();
 515         if (rc) {
 516                 put_tty_driver(driver);
 517                 return rc;
 518         }
 519         /* Allocate pages for output buffering */
 520         INIT_LIST_HEAD(&sclp_tty_pages);
 521         for (i = 0; i < MAX_KMEM_PAGES; i++) {
 522                 page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 523                 if (page == NULL) {
 524                         put_tty_driver(driver);
 525                         return -ENOMEM;
 526                 }
 527                 list_add_tail((struct list_head *) page, &sclp_tty_pages);
 528         }
 529         INIT_LIST_HEAD(&sclp_tty_outqueue);
 530         spin_lock_init(&sclp_tty_lock);
 531         timer_setup(&sclp_tty_timer, sclp_tty_timeout, 0);
 532         sclp_ttybuf = NULL;
 533         sclp_tty_buffer_count = 0;
 534         if (MACHINE_IS_VM) {
 535                 /*
 536                  * save 4 characters for the CPU number
 537                  * written at start of each line by VM/CP
 538                  */
 539                 sclp_tty_columns = 76;
 540                 /* case input lines to lowercase */
 541                 sclp_tty_tolower = 1;
 542         }
 543         sclp_tty_chars_count = 0;
 544
 545         rc = sclp_register(&sclp_input_event);
 546         if (rc) {
 547                 put_tty_driver(driver);
 548                 return rc;
 549         }
 550
 551         tty_port_init(&sclp_port);
 552
 553         driver->driver_name = "sclp_line";
 554         driver->name = "sclp_line";
 555         driver->major = TTY_MAJOR;
 556         driver->minor_start = 64;
 557         driver->type = TTY_DRIVER_TYPE_SYSTEM;
 558         driver->subtype = SYSTEM_TYPE_TTY;
 559         driver->init_termios = tty_std_termios;
 560         driver->init_termios.c_iflag = IGNBRK | IGNPAR;
 561         driver->init_termios.c_oflag = ONLCR;
 562         driver->init_termios.c_lflag = ISIG | ECHO;
 563         driver->flags = TTY_DRIVER_REAL_RAW;
 564         tty_set_operations(driver, &sclp_ops);
 565         tty_port_link_device(&sclp_port, driver, 0);
 566         rc = tty_register_driver(driver);
 567         if (rc) {
 568                 put_tty_driver(driver);
 569                 tty_port_destroy(&sclp_port);
 570                 return rc;
 571         }
 572         sclp_tty_driver = driver;
 573         return 0;
 574 }
 575 device_initcall(sclp_tty_init);