com.c revision 1.14
1 /*- 2 * Copyright (c) 1991 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * from: @(#)com.c 7.5 (Berkeley) 5/16/91 34 * $Id: com.c,v 1.14 1993/12/20 09:05:33 mycroft Exp $ 35 */ 36 37 #include "com.h" 38 #if NCOM > 0 39 /* 40 * COM driver, based on HP dca driver 41 * uses National Semiconductor NS16450/NS16550AF UART 42 */ 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/ioctl.h> 46 #include <sys/select.h> 47 #include <sys/tty.h> 48 #include <sys/proc.h> 49 #include <sys/user.h> 50 #include <sys/conf.h> 51 #include <sys/file.h> 52 #include <sys/uio.h> 53 #include <sys/kernel.h> 54 #include <sys/syslog.h> 55 #include <sys/types.h> 56 57 #include <machine/pio.h> 58 59 #include <i386/isa/isa_device.h> 60 #include <i386/isa/comreg.h> 61 #include <i386/isa/ic/ns16550.h> 62 63 #define cominor(d) 64 65 int comprobe(), comattach(), comintr(), comparam(); 66 void comstart(); 67 68 struct isa_driver comdriver = { 69 comprobe, comattach, "com" 70 }; 71 72 int comsoftCAR; 73 int com_active; 74 int com_hasfifo; 75 int ncom = NCOM; 76 #ifdef COMCONSOLE 77 int comconsole = COMCONSOLE; 78 #else 79 int comconsole = -1; 80 #endif 81 int comconsinit; 82 int comdefaultrate = TTYDEF_SPEED; 83 int commajor; 84 short com_addr[NCOM]; 85 struct tty *com_tty[NCOM]; 86 87 struct speedtab comspeedtab[] = { 88 0, 0, 89 50, COMBRD(50), 90 75, COMBRD(75), 91 110, COMBRD(110), 92 134, COMBRD(134), 93 150, COMBRD(150), 94 200, COMBRD(200), 95 300, COMBRD(300), 96 600, COMBRD(600), 97 1200, COMBRD(1200), 98 1800, COMBRD(1800), 99 2400, COMBRD(2400), 100 4800, COMBRD(4800), 101 9600, COMBRD(9600), 102 19200, COMBRD(19200), 103 38400, COMBRD(38400), 104 57600, COMBRD(57600), 105 -1, -1 106 }; 107 108 extern struct tty *constty; 109 #ifdef KGDB 110 #include <machine/remote-sl.h> 111 112 extern int kgdb_dev; 113 extern int kgdb_rate; 114 extern int kgdb_debug_init; 115 #endif 116 117 #define UNIT(x) (minor(x)) 118 119 comprobe(dev) 120 struct isa_device *dev; 121 { 122 /* force access to id reg */ 123 outb(dev->id_iobase+com_cfcr, 0); 124 outb(dev->id_iobase+com_iir, 0); 125 DELAY(100); 126 if ((inb(dev->id_iobase+com_iir) & 0x38) == 0) 127 return(8); 128 return(0); 129 } 130 131 132 int 133 comattach(isdp) 134 struct isa_device *isdp; 135 { 136 struct tty *tp; 137 u_char unit; 138 int port = isdp->id_iobase; 139 140 unit = isdp->id_unit; 141 if (unit == comconsole) 142 DELAY(1000); 143 com_addr[unit] = port; 144 com_active |= 1 << unit; 145 comsoftCAR |= 1 << unit; /* XXX */ 146 147 /* look for a NS 16550AF UART with FIFOs */ 148 outb(port+com_fifo, FIFO_ENABLE|FIFO_RCV_RST|FIFO_XMT_RST|FIFO_TRIGGER_4); 149 DELAY(100); 150 if ((inb(port+com_iir) & IIR_FIFO_MASK) == IIR_FIFO_MASK) { 151 com_hasfifo |= 1 << unit; 152 printf("com%d: fifo\n", isdp->id_unit); 153 } 154 155 outb(port+com_ier, 0); 156 outb(port+com_mcr, 0 | MCR_IENABLE); 157 #ifdef KGDB 158 if (kgdb_dev == makedev(commajor, unit)) { 159 if (comconsole == unit) 160 kgdb_dev = -1; /* can't debug over console port */ 161 else { 162 (void) cominit(unit, kgdb_rate); 163 if (kgdb_debug_init) { 164 /* 165 * Print prefix of device name, 166 * let kgdb_connect print the rest. 167 */ 168 printf("com%d: ", unit); 169 kgdb_connect(1); 170 } else 171 printf("com%d: kgdb enabled\n", unit); 172 } 173 } 174 #endif 175 /* 176 * Need to reset baud rate, etc. of next print so reset comconsinit. 177 * Also make sure console is always "hardwired" 178 */ 179 if (unit == comconsole) { 180 comconsinit = 0; 181 comsoftCAR |= (1 << unit); 182 } 183 return (1); 184 } 185 186 /* ARGSUSED */ 187 comopen(dev_t dev, int flag, int mode, struct proc *p) 188 { 189 register struct tty *tp; 190 register int unit; 191 int error = 0; 192 193 unit = UNIT(dev); 194 if (unit >= NCOM || (com_active & (1 << unit)) == 0) 195 return (ENXIO); 196 if(!com_tty[unit]) { 197 tp = com_tty[unit] = ttymalloc(); 198 } else 199 tp = com_tty[unit]; 200 tp->t_oproc = comstart; 201 tp->t_param = comparam; 202 tp->t_dev = dev; 203 if ((tp->t_state & TS_ISOPEN) == 0) { 204 tp->t_state |= TS_WOPEN; 205 ttychars(tp); 206 if (tp->t_ispeed == 0) { 207 tp->t_iflag = TTYDEF_IFLAG; 208 tp->t_oflag = TTYDEF_OFLAG; 209 tp->t_cflag = TTYDEF_CFLAG; 210 tp->t_lflag = TTYDEF_LFLAG; 211 tp->t_ispeed = tp->t_ospeed = comdefaultrate; 212 } 213 comparam(tp, &tp->t_termios); 214 ttsetwater(tp); 215 } else if (tp->t_state&TS_XCLUDE && p->p_ucred->cr_uid != 0) 216 return (EBUSY); 217 (void) spltty(); 218 (void) commctl(dev, MCR_DTR | MCR_RTS, DMSET); 219 if ((comsoftCAR & (1 << unit)) || (commctl(dev, 0, DMGET) & MSR_DCD)) 220 tp->t_state |= TS_CARR_ON; 221 while ((flag&O_NONBLOCK) == 0 && (tp->t_cflag&CLOCAL) == 0 && 222 (tp->t_state & TS_CARR_ON) == 0) { 223 tp->t_state |= TS_WOPEN; 224 if (error = ttysleep(tp, (caddr_t)&tp->t_rawq, TTIPRI | PCATCH, 225 ttopen, 0)) 226 break; 227 } 228 (void) spl0(); 229 if (error == 0) 230 error = (*linesw[tp->t_line].l_open)(dev, tp); 231 return (error); 232 } 233 234 /*ARGSUSED*/ 235 comclose(dev, flag, mode, p) 236 dev_t dev; 237 int flag, mode; 238 struct proc *p; 239 { 240 register struct tty *tp; 241 register com; 242 register int unit; 243 244 unit = UNIT(dev); 245 com = com_addr[unit]; 246 tp = com_tty[unit]; 247 (*linesw[tp->t_line].l_close)(tp, flag); 248 outb(com+com_cfcr, inb(com+com_cfcr) & ~CFCR_SBREAK); 249 #ifdef KGDB 250 /* do not disable interrupts if debugging */ 251 if (kgdb_dev != makedev(commajor, unit)) 252 #endif 253 outb(com+com_ier, 0); 254 if (tp->t_cflag&HUPCL || tp->t_state&TS_WOPEN || 255 (tp->t_state&TS_ISOPEN) == 0) 256 (void) commctl(dev, 0, DMSET); 257 ttyclose(tp); 258 #ifdef broken /* session holds a ref to the tty; can't deallocate */ 259 ttyfree(tp); 260 com_tty[unit] = (struct tty *)NULL; 261 #endif 262 return(0); 263 } 264 265 comread(dev, uio, flag) 266 dev_t dev; 267 struct uio *uio; 268 { 269 register struct tty *tp = com_tty[UNIT(dev)]; 270 271 return ((*linesw[tp->t_line].l_read)(tp, uio, flag)); 272 } 273 274 comwrite(dev, uio, flag) 275 dev_t dev; 276 struct uio *uio; 277 { 278 int unit = UNIT(dev); 279 register struct tty *tp = com_tty[unit]; 280 281 /* 282 * (XXX) We disallow virtual consoles if the physical console is 283 * a serial port. This is in case there is a display attached that 284 * is not the console. In that situation we don't need/want the X 285 * server taking over the console. 286 */ 287 if (constty && unit == comconsole) 288 constty = NULL; 289 return ((*linesw[tp->t_line].l_write)(tp, uio, flag)); 290 } 291 292 comintr(unit) 293 register int unit; 294 { 295 register com; 296 register u_char code; 297 register struct tty *tp; 298 299 unit; 300 com = com_addr[unit]; 301 while (1) { 302 code = inb(com+com_iir); 303 switch (code & IIR_IMASK) { 304 case IIR_NOPEND: 305 return (1); 306 case IIR_RXTOUT: 307 case IIR_RXRDY: 308 tp = com_tty[unit]; 309 /* 310 * Process received bytes. Inline for speed... 311 */ 312 #ifdef KGDB 313 #define RCVBYTE() \ 314 code = inb(com+com_data); \ 315 if ((tp->t_state & TS_ISOPEN) == 0) { \ 316 if (kgdb_dev == makedev(commajor, unit) && \ 317 code == FRAME_END) \ 318 kgdb_connect(0); /* trap into kgdb */ \ 319 } else \ 320 (*linesw[tp->t_line].l_rint)(code, tp) 321 #else 322 #define RCVBYTE() \ 323 code = inb(com+com_data); \ 324 if (tp->t_state & TS_ISOPEN) \ 325 (*linesw[tp->t_line].l_rint)(code, tp) 326 #endif 327 328 RCVBYTE(); 329 330 if (com_hasfifo & (1 << unit)) 331 while ((code = inb(com+com_lsr)) & LSR_RCV_MASK) { 332 if (code == LSR_RXRDY) { 333 RCVBYTE(); 334 } else 335 comeint(unit, code, com); 336 } 337 break; 338 case IIR_TXRDY: 339 tp = com_tty[unit]; 340 tp->t_state &=~ (TS_BUSY|TS_FLUSH); 341 if (tp->t_line) 342 (*linesw[tp->t_line].l_start)(tp); 343 else 344 comstart(tp); 345 break; 346 case IIR_RLS: 347 comeint(unit, inb(com+com_lsr), com); 348 break; 349 default: 350 if (code & IIR_NOPEND) 351 return (1); 352 log(LOG_WARNING, "com%d: weird interrupt: 0x%x\n", 353 unit, code); 354 /* fall through */ 355 case IIR_MLSC: 356 commint(unit, com); 357 break; 358 } 359 } 360 } 361 362 comeint(unit, stat, com) 363 register int unit, stat; 364 register com; 365 { 366 register struct tty *tp; 367 register int c; 368 369 tp = com_tty[unit]; 370 c = inb(com+com_data); 371 if ((tp->t_state & TS_ISOPEN) == 0) { 372 #ifdef KGDB 373 /* we don't care about parity errors */ 374 if (((stat & (LSR_BI|LSR_FE|LSR_PE)) == LSR_PE) && 375 kgdb_dev == makedev(commajor, unit) && c == FRAME_END) 376 kgdb_connect(0); /* trap into kgdb */ 377 #endif 378 return; 379 } 380 if (stat & (LSR_BI | LSR_FE)) 381 c |= TTY_FE; 382 else if (stat & LSR_PE) 383 c |= TTY_PE; 384 else if (stat & LSR_OE) { /* 30 Aug 92*/ 385 c |= TTY_PE; /* Ought to have it's own define... */ 386 log(LOG_WARNING, "com%d: silo overflow\n", unit); 387 } 388 (*linesw[tp->t_line].l_rint)(c, tp); 389 } 390 391 commint(unit, com) 392 register int unit; 393 register com; 394 { 395 register struct tty *tp; 396 register int stat; 397 398 tp = com_tty[unit]; 399 stat = inb(com+com_msr); 400 if ((stat & MSR_DDCD) && (comsoftCAR & (1 << unit)) == 0) { 401 if (stat & MSR_DCD) 402 (void)(*linesw[tp->t_line].l_modem)(tp, 1); 403 else if ((*linesw[tp->t_line].l_modem)(tp, 0) == 0) 404 outb(com+com_mcr, 405 inb(com+com_mcr) & ~(MCR_DTR | MCR_RTS) | MCR_IENABLE); 406 } else if ((stat & MSR_DCTS) && (tp->t_state & TS_ISOPEN) && 407 (tp->t_flags & CRTSCTS)) { 408 /* the line is up and we want to do rts/cts flow control */ 409 if (stat & MSR_CTS) { 410 tp->t_state &=~ TS_TTSTOP; 411 ttstart(tp); 412 } else 413 tp->t_state |= TS_TTSTOP; 414 } 415 } 416 417 comioctl(dev, cmd, data, flag) 418 dev_t dev; 419 caddr_t data; 420 { 421 register struct tty *tp; 422 register int unit = UNIT(dev); 423 register com; 424 register int error; 425 426 tp = com_tty[unit]; 427 error = (*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag); 428 if (error >= 0) 429 return (error); 430 error = ttioctl(tp, cmd, data, flag); 431 if (error >= 0) 432 return (error); 433 434 com = com_addr[unit]; 435 switch (cmd) { 436 437 case TIOCSBRK: 438 outb(com+com_cfcr, inb(com+com_cfcr) | CFCR_SBREAK); 439 break; 440 441 case TIOCCBRK: 442 outb(com+com_cfcr, inb(com+com_cfcr) & ~CFCR_SBREAK); 443 break; 444 445 case TIOCSDTR: 446 (void) commctl(dev, MCR_DTR | MCR_RTS, DMBIS); 447 break; 448 449 case TIOCCDTR: 450 (void) commctl(dev, MCR_DTR | MCR_RTS, DMBIC); 451 break; 452 453 case TIOCMSET: 454 (void) commctl(dev, *(int *)data, DMSET); 455 break; 456 457 case TIOCMBIS: 458 (void) commctl(dev, *(int *)data, DMBIS); 459 break; 460 461 case TIOCMBIC: 462 (void) commctl(dev, *(int *)data, DMBIC); 463 break; 464 465 case TIOCMGET: 466 *(int *)data = commctl(dev, 0, DMGET); 467 break; 468 469 default: 470 return (ENOTTY); 471 } 472 return (0); 473 } 474 475 comparam(tp, t) 476 register struct tty *tp; 477 register struct termios *t; 478 { 479 register com; 480 register int cfcr, cflag = t->c_cflag; 481 int unit = UNIT(tp->t_dev); 482 int ospeed = ttspeedtab(t->c_ospeed, comspeedtab); 483 484 /* check requested parameters */ 485 if (ospeed < 0 || (t->c_ispeed && t->c_ispeed != t->c_ospeed)) 486 return(EINVAL); 487 /* and copy to tty */ 488 tp->t_ispeed = t->c_ispeed; 489 tp->t_ospeed = t->c_ospeed; 490 tp->t_cflag = cflag; 491 492 com = com_addr[unit]; 493 outb(com+com_ier, IER_ERXRDY | IER_ETXRDY | IER_ERLS /*| IER_EMSC*/); 494 if (ospeed == 0) { 495 (void) commctl(unit, 0, DMSET); /* hang up line */ 496 return(0); 497 } 498 outb(com+com_cfcr, inb(com+com_cfcr) | CFCR_DLAB); 499 outb(com+com_data, ospeed & 0xFF); 500 outb(com+com_ier, ospeed >> 8); 501 switch (cflag&CSIZE) { 502 case CS5: 503 cfcr = CFCR_5BITS; break; 504 case CS6: 505 cfcr = CFCR_6BITS; break; 506 case CS7: 507 cfcr = CFCR_7BITS; break; 508 case CS8: 509 cfcr = CFCR_8BITS; break; 510 } 511 if (cflag&PARENB) { 512 cfcr |= CFCR_PENAB; 513 if ((cflag&PARODD) == 0) 514 cfcr |= CFCR_PEVEN; 515 } 516 if (cflag&CSTOPB) 517 cfcr |= CFCR_STOPB; 518 outb(com+com_cfcr, cfcr); 519 520 if (com_hasfifo & (1 << unit)) 521 outb(com+com_fifo, FIFO_ENABLE | FIFO_TRIGGER_4); 522 523 return(0); 524 } 525 526 void 527 comstart(tp) 528 register struct tty *tp; 529 { 530 register com; 531 int s, unit, c; 532 533 unit = UNIT(tp->t_dev); 534 com = com_addr[unit]; 535 s = spltty(); 536 if (tp->t_state & (TS_TIMEOUT|TS_TTSTOP)) 537 goto out; 538 if (tp->t_outq.c_cc <= tp->t_lowat) { 539 if (tp->t_state&TS_ASLEEP) { 540 tp->t_state &= ~TS_ASLEEP; 541 wakeup((caddr_t)&tp->t_outq); 542 } 543 selwakeup(&tp->t_wsel); 544 } 545 if (tp->t_outq.c_cc == 0) 546 goto out; 547 if (inb(com+com_lsr) & LSR_TXRDY) { 548 c = getc(&tp->t_outq); 549 tp->t_state |= TS_BUSY; 550 outb(com+com_data, c); 551 if (com_hasfifo & (1 << unit)) 552 for (c = 1; c < 16 && tp->t_outq.c_cc; ++c) 553 outb(com+com_data, getc(&tp->t_outq)); 554 } 555 out: 556 splx(s); 557 } 558 559 /* 560 * Stop output on a line. 561 */ 562 /*ARGSUSED*/ 563 comstop(tp, flag) 564 register struct tty *tp; 565 { 566 register int s; 567 568 s = spltty(); 569 if (tp->t_state & TS_BUSY) { 570 if ((tp->t_state&TS_TTSTOP)==0) 571 tp->t_state |= TS_FLUSH; 572 } 573 splx(s); 574 } 575 576 commctl(dev, bits, how) 577 dev_t dev; 578 int bits, how; 579 { 580 register com; 581 register int unit; 582 int s; 583 584 unit = UNIT(dev); 585 com = com_addr[unit]; 586 s = spltty(); 587 switch (how) { 588 589 case DMSET: 590 outb(com+com_mcr, bits | MCR_IENABLE); 591 break; 592 593 case DMBIS: 594 outb(com+com_mcr, inb(com+com_mcr) | bits | MCR_IENABLE); 595 break; 596 597 case DMBIC: 598 outb(com+com_mcr, inb(com+com_mcr) & ~bits | MCR_IENABLE); 599 break; 600 601 case DMGET: 602 bits = inb(com+com_msr); 603 break; 604 } 605 (void) splx(s); 606 return(bits); 607 } 608 609 /* 610 * Following are all routines needed for COM to act as console 611 */ 612 #include <i386/i386/cons.h> 613 614 comcnprobe(cp) 615 struct consdev *cp; 616 { 617 int unit; 618 619 /* locate the major number */ 620 for (commajor = 0; commajor < nchrdev; commajor++) 621 if (cdevsw[commajor].d_open == comopen) 622 break; 623 624 /* XXX: ick */ 625 unit = CONUNIT; 626 com_addr[CONUNIT] = CONADDR; 627 628 /* make sure hardware exists? XXX */ 629 630 /* initialize required fields */ 631 cp->cn_dev = makedev(commajor, unit); 632 #ifdef COMCONSOLE 633 cp->cn_pri = CN_REMOTE; /* Force a serial port console */ 634 #else 635 cp->cn_pri = CN_NORMAL; 636 #endif 637 } 638 639 comcninit(cp) 640 struct consdev *cp; 641 { 642 int unit = UNIT(cp->cn_dev); 643 644 cominit(unit, comdefaultrate); 645 comconsole = unit; 646 comconsinit = 1; 647 } 648 649 cominit(unit, rate) 650 int unit, rate; 651 { 652 register int com; 653 int s; 654 short stat; 655 656 #ifdef lint 657 stat = unit; if (stat) return; 658 #endif 659 com = com_addr[unit]; 660 s = splhigh(); 661 outb(com+com_cfcr, CFCR_DLAB); 662 rate = ttspeedtab(comdefaultrate, comspeedtab); 663 outb(com+com_data, rate & 0xFF); 664 outb(com+com_ier, rate >> 8); 665 outb(com+com_cfcr, CFCR_8BITS); 666 outb(com+com_ier, IER_ERXRDY | IER_ETXRDY); 667 outb(com+com_fifo, FIFO_ENABLE|FIFO_RCV_RST|FIFO_XMT_RST|FIFO_TRIGGER_4); 668 stat = inb(com+com_iir); 669 splx(s); 670 } 671 672 comcngetc(dev) 673 { 674 register com = com_addr[UNIT(dev)]; 675 short stat; 676 int c, s; 677 678 #ifdef lint 679 stat = dev; if (stat) return(0); 680 #endif 681 s = splhigh(); 682 while (((stat = inb(com+com_lsr)) & LSR_RXRDY) == 0) 683 ; 684 c = inb(com+com_data); 685 stat = inb(com+com_iir); 686 splx(s); 687 return(c); 688 } 689 690 /* 691 * Console kernel output character routine. 692 */ 693 comcnputc(dev, c) 694 dev_t dev; 695 register int c; 696 { 697 register com = com_addr[UNIT(dev)]; 698 register int timo; 699 short stat; 700 int s = splhigh(); 701 702 #ifdef lint 703 stat = dev; if (stat) return; 704 #endif 705 #ifdef KGDB 706 if (dev != kgdb_dev) 707 #endif 708 if (comconsinit == 0) { 709 (void) cominit(UNIT(dev), comdefaultrate); 710 comconsinit = 1; 711 } 712 /* wait for any pending transmission to finish */ 713 timo = 50000; 714 while (((stat = inb(com+com_lsr)) & LSR_TXRDY) == 0 && --timo) 715 ; 716 outb(com+com_data, c); 717 /* wait for this transmission to complete */ 718 timo = 1500000; 719 while (((stat = inb(com+com_lsr)) & LSR_TXRDY) == 0 && --timo) 720 ; 721 /* clear any interrupts generated by this transmission */ 722 stat = inb(com+com_iir); 723 splx(s); 724 } 725 726 int 727 comselect(dev, rw, p) 728 dev_t dev; 729 int rw; 730 struct proc *p; 731 { 732 register struct tty *tp = com_tty[UNIT(dev)]; 733 int nread; 734 int s = spltty(); 735 struct proc *selp; 736 737 switch (rw) { 738 739 case FREAD: 740 nread = ttnread(tp); 741 if (nread > 0 || 742 ((tp->t_cflag&CLOCAL) == 0 && (tp->t_state&TS_CARR_ON) == 0)) 743 goto win; 744 selrecord(p, &tp->t_rsel); 745 break; 746 747 case FWRITE: 748 if (tp->t_outq.c_cc <= tp->t_lowat) 749 goto win; 750 selrecord(p, &tp->t_wsel); 751 break; 752 } 753 splx(s); 754 return (0); 755 win: 756 splx(s); 757 return (1); 758 } 759 760 #endif 761
Indexes created Mon Sep 22 13:09:51 GMT 2025