/* $NetBSD: dca.c,v 1.17 1995/10/04 17:46:08 thorpej Exp $ */ /* * Copyright (c) 1982, 1986, 1990, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)dca.c 8.2 (Berkeley) 1/12/94 */ #include "dca.h" #if NDCA > 0 /* * Driver for National Semiconductor INS8250/NS16550AF/WD16C552 UARTs. * Includes: * 98626/98644/internal serial interface on hp300/hp400 * internal serial ports on hp700 * * N.B. On the hp700 and some hp300s, there is a "secret bit" with * undocumented behavior. The third bit of the Modem Control Register * (MCR_IEN == 0x08) must be set to enable interrupts. Failure to do * so can result in deadlock on those machines, whereas the don't seem to * be any harmful side-effects from setting this bit on non-affected * machines. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef hp300 #include #endif #ifdef hp700 #include #endif int dcaprobe(); struct driver dcadriver = { dcaprobe, "dca", }; void dcastart(); int dcaparam(), dcaintr(); int dcasoftCAR; int dca_active; int dca_hasfifo; int ndca = NDCA; #ifdef DCACONSOLE int dcaconsole = DCACONSOLE; #else int dcaconsole = -1; #endif int dcaconsinit; int dcadefaultrate = TTYDEF_SPEED; int dcamajor; struct dcadevice *dca_addr[NDCA]; struct tty *dca_tty[NDCA]; #ifdef hp300 struct isr dcaisr[NDCA]; int dcafastservice; #endif int dcaoflows[NDCA]; struct speedtab dcaspeedtab[] = { 0, 0, 50, DCABRD(50), 75, DCABRD(75), 110, DCABRD(110), 134, DCABRD(134), 150, DCABRD(150), 200, DCABRD(200), 300, DCABRD(300), 600, DCABRD(600), 1200, DCABRD(1200), 1800, DCABRD(1800), 2400, DCABRD(2400), 4800, DCABRD(4800), 9600, DCABRD(9600), 19200, DCABRD(19200), 38400, DCABRD(38400), -1, -1 }; #ifdef KGDB #include extern dev_t kgdb_dev; extern int kgdb_rate; extern int kgdb_debug_init; #endif #define UNIT(x) minor(x) #ifdef DEBUG long fifoin[17]; long fifoout[17]; long dcaintrcount[16]; long dcamintcount[16]; #endif dcaprobe(hd) register struct hp_device *hd; { register struct dcadevice *dca; register int unit; dca = (struct dcadevice *)hd->hp_addr; #ifdef hp300 if (dca->dca_id != DCAID0 && dca->dca_id != DCAREMID0 && dca->dca_id != DCAID1 && dca->dca_id != DCAREMID1) return (0); #endif unit = hd->hp_unit; if (unit == dcaconsole) DELAY(100000); #ifdef hp300 dca->dca_reset = 0xFF; DELAY(100); #endif /* look for a NS 16550AF UART with FIFOs */ dca->dca_fifo = FIFO_ENABLE|FIFO_RCV_RST|FIFO_XMT_RST|FIFO_TRIGGER_14; DELAY(100); if ((dca->dca_iir & IIR_FIFO_MASK) == IIR_FIFO_MASK) dca_hasfifo |= 1 << unit; dca_addr[unit] = dca; #ifdef hp300 hd->hp_ipl = DCAIPL(dca->dca_ic); dcaisr[unit].isr_ipl = hd->hp_ipl; dcaisr[unit].isr_arg = unit; dcaisr[unit].isr_intr = dcaintr; isrlink(&dcaisr[unit]); #endif dca_active |= 1 << unit; if (hd->hp_flags) dcasoftCAR |= (1 << unit); #ifdef KGDB if (kgdb_dev == makedev(dcamajor, unit)) { if (dcaconsole == unit) kgdb_dev = NODEV; /* can't debug over console port */ else { (void) dcainit(unit, kgdb_rate); dcaconsinit = 1; /* don't re-init in dcaputc */ if (kgdb_debug_init) { /* * Print prefix of device name, * let kgdb_connect print the rest. */ printf("dca%d: ", unit); kgdb_connect(1); } else printf("dca%d: kgdb enabled\n", unit); } } #endif #ifdef hp300 dca->dca_ic = IC_IE; #endif /* * Need to reset baud rate, etc. of next print so reset dcaconsinit. * Also make sure console is always "hardwired." */ if (unit == dcaconsole) { dcaconsinit = 0; dcasoftCAR |= (1 << unit); printf("dca%d: console, ", unit); } else printf("dca%d: ", unit); if (dca_hasfifo & (1 << unit)) printf("working fifo\n"); else printf("no fifo\n"); return (1); } /* ARGSUSED */ int dcaopen(dev, flag, mode, p) dev_t dev; int flag, mode; struct proc *p; { register struct tty *tp; register int unit; struct dcadevice *dca; u_char code; int s, error = 0; unit = UNIT(dev); if (unit >= NDCA || (dca_active & (1 << unit)) == 0) return (ENXIO); if (!dca_tty[unit]) tp = dca_tty[unit] = ttymalloc(); else tp = dca_tty[unit]; tp->t_oproc = dcastart; tp->t_param = dcaparam; tp->t_dev = dev; dca = dca_addr[unit]; if ((tp->t_state & TS_ISOPEN) == 0) { /* * Sanity clause: reset the card on first open. * The card might be left in an inconsistent state * if card memory is read inadvertently. */ dcainit(unit, dcadefaultrate); tp->t_state |= TS_WOPEN; ttychars(tp); tp->t_iflag = TTYDEF_IFLAG; tp->t_oflag = TTYDEF_OFLAG; tp->t_cflag = TTYDEF_CFLAG; tp->t_lflag = TTYDEF_LFLAG; tp->t_ispeed = tp->t_ospeed = dcadefaultrate; s = spltty(); dcaparam(tp, &tp->t_termios); ttsetwater(tp); /* Set the FIFO threshold based on the receive speed. */ if (dca_hasfifo & (1 << unit)) dca->dca_fifo = FIFO_ENABLE | FIFO_RCV_RST | FIFO_XMT_RST | (tp->t_ispeed <= 1200 ? FIFO_TRIGGER_1 : FIFO_TRIGGER_14); /* Flush any pending I/O */ while ((dca->dca_iir & IIR_IMASK) == IIR_RXRDY) code = dca->dca_data; } else if (tp->t_state&TS_XCLUDE && p->p_ucred->cr_uid != 0) return (EBUSY); else s = spltty(); /* Set modem control state. */ (void) dcamctl(dev, MCR_DTR | MCR_RTS, DMSET); /* Set soft-carrier if so configured. */ if ((dcasoftCAR & (1 << unit)) || (dcamctl(dev, 0, DMGET) & MSR_DCD)) tp->t_state |= TS_CARR_ON; /* Wait for carrier if necessary. */ if ((flag & O_NONBLOCK) == 0) while ((tp->t_cflag & CLOCAL) == 0 && (tp->t_state & TS_CARR_ON) == 0) { tp->t_state |= TS_WOPEN; error = ttysleep(tp, (caddr_t)&tp->t_rawq, TTIPRI | PCATCH, ttopen, 0); if (error) { splx(s); return (error); } } splx(s); if (error == 0) error = (*linesw[tp->t_line].l_open)(dev, tp); #ifdef hp300 /* * XXX hack to speed up unbuffered builtin port. * If dca_fastservice is set, a level 5 interrupt * will be directed to dcaintr first. */ if (error == 0 && unit == 0 && (dca_hasfifo & 1) == 0) dcafastservice = 1; #endif return (error); } /*ARGSUSED*/ int dcaclose(dev, flag, mode, p) dev_t dev; int flag, mode; struct proc *p; { register struct tty *tp; register struct dcadevice *dca; register int unit; int s; unit = UNIT(dev); #ifdef hp300 if (unit == 0) dcafastservice = 0; #endif dca = dca_addr[unit]; tp = dca_tty[unit]; (*linesw[tp->t_line].l_close)(tp, flag); s = spltty(); dca->dca_cfcr &= ~CFCR_SBREAK; #ifdef KGDB /* do not disable interrupts if debugging */ if (dev != kgdb_dev) #endif dca->dca_ier = 0; if (tp->t_cflag & HUPCL && (dcasoftCAR & (1 << unit)) == 0) { /* XXX perhaps only clear DTR */ (void) dcamctl(dev, 0, DMSET); } tp->t_state &= ~(TS_BUSY | TS_FLUSH); splx(s); ttyclose(tp); #if 0 ttyfree(tp); dca_tty[unit] = (struct tty *)0; #endif return (0); } int dcaread(dev, uio, flag) dev_t dev; struct uio *uio; int flag; { int unit = UNIT(dev); register struct tty *tp = dca_tty[unit]; int error, of; of = dcaoflows[unit]; error = (*linesw[tp->t_line].l_read)(tp, uio, flag); /* * XXX hardly a reasonable thing to do, but reporting overflows * at interrupt time just exacerbates the problem. */ if (dcaoflows[unit] != of) log(LOG_WARNING, "dca%d: silo overflow\n", unit); return (error); } int dcawrite(dev, uio, flag) dev_t dev; struct uio *uio; int flag; { register struct tty *tp = dca_tty[UNIT(dev)]; return ((*linesw[tp->t_line].l_write)(tp, uio, flag)); } struct tty * dcatty(dev) dev_t dev; { return (dca_tty[UNIT(dev)]); } int dcaintr(unit) register int unit; { register struct dcadevice *dca; register u_char code; register struct tty *tp; int iflowdone = 0; dca = dca_addr[unit]; #ifdef hp300 if ((dca->dca_ic & (IC_IR|IC_IE)) != (IC_IR|IC_IE)) return (0); #endif tp = dca_tty[unit]; for (;;) { code = dca->dca_iir; #ifdef DEBUG dcaintrcount[code & IIR_IMASK]++; #endif switch (code & IIR_IMASK) { case IIR_NOPEND: return (1); case IIR_RXTOUT: case IIR_RXRDY: /* do time-critical read in-line */ /* * Process a received byte. Inline for speed... */ #ifdef KGDB #define RCVBYTE() \ code = dca->dca_data; \ if ((tp->t_state & TS_ISOPEN) == 0) { \ if (code == FRAME_END && \ kgdb_dev == makedev(dcamajor, unit)) \ kgdb_connect(0); /* trap into kgdb */ \ } else \ (*linesw[tp->t_line].l_rint)(code, tp) #else #define RCVBYTE() \ code = dca->dca_data; \ if ((tp->t_state & TS_ISOPEN) != 0) \ (*linesw[tp->t_line].l_rint)(code, tp) #endif RCVBYTE(); if (dca_hasfifo & (1 << unit)) { #ifdef DEBUG register int fifocnt = 1; #endif while ((code = dca->dca_lsr) & LSR_RCV_MASK) { if (code == LSR_RXRDY) { RCVBYTE(); } else dcaeint(unit, code, dca); #ifdef DEBUG fifocnt++; #endif } #ifdef DEBUG if (fifocnt > 16) fifoin[0]++; else fifoin[fifocnt]++; #endif } if (!iflowdone && (tp->t_cflag&CRTS_IFLOW) && tp->t_rawq.c_cc > TTYHOG/2) { dca->dca_mcr &= ~MCR_RTS; iflowdone = 1; } break; case IIR_TXRDY: tp->t_state &=~ (TS_BUSY|TS_FLUSH); if (tp->t_line) (*linesw[tp->t_line].l_start)(tp); else dcastart(tp); break; case IIR_RLS: dcaeint(unit, dca->dca_lsr, dca); break; default: if (code & IIR_NOPEND) return (1); log(LOG_WARNING, "dca%d: weird interrupt: 0x%x\n", unit, code); /* fall through */ case IIR_MLSC: dcamint(unit, dca); break; } } } dcaeint(unit, stat, dca) register int unit, stat; register struct dcadevice *dca; { register struct tty *tp; register int c; tp = dca_tty[unit]; c = dca->dca_data; if ((tp->t_state & TS_ISOPEN) == 0) { #ifdef KGDB /* we don't care about parity errors */ if (((stat & (LSR_BI|LSR_FE|LSR_PE)) == LSR_PE) && kgdb_dev == makedev(dcamajor, unit) && c == FRAME_END) kgdb_connect(0); /* trap into kgdb */ #endif return; } if (stat & (LSR_BI | LSR_FE)) c |= TTY_FE; else if (stat & LSR_PE) c |= TTY_PE; else if (stat & LSR_OE) dcaoflows[unit]++; (*linesw[tp->t_line].l_rint)(c, tp); } dcamint(unit, dca) register int unit; register struct dcadevice *dca; { register struct tty *tp; register u_char stat; tp = dca_tty[unit]; stat = dca->dca_msr; #ifdef DEBUG dcamintcount[stat & 0xf]++; #endif if ((stat & MSR_DDCD) && (dcasoftCAR & (1 << unit)) == 0) { if (stat & MSR_DCD) (void)(*linesw[tp->t_line].l_modem)(tp, 1); else if ((*linesw[tp->t_line].l_modem)(tp, 0) == 0) dca->dca_mcr &= ~(MCR_DTR | MCR_RTS); } /* * CTS change. * If doing HW output flow control start/stop output as appropriate. */ if ((stat & MSR_DCTS) && (tp->t_state & TS_ISOPEN) && (tp->t_cflag & CCTS_OFLOW)) { if (stat & MSR_CTS) { tp->t_state &=~ TS_TTSTOP; dcastart(tp); } else { tp->t_state |= TS_TTSTOP; } } } int dcaioctl(dev, cmd, data, flag, p) dev_t dev; int cmd; caddr_t data; int flag; struct proc *p; { register struct tty *tp; register int unit = UNIT(dev); register struct dcadevice *dca; register int error; tp = dca_tty[unit]; error = (*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag, p); if (error >= 0) return (error); error = ttioctl(tp, cmd, data, flag, p); if (error >= 0) return (error); dca = dca_addr[unit]; switch (cmd) { case TIOCSBRK: dca->dca_cfcr |= CFCR_SBREAK; break; case TIOCCBRK: dca->dca_cfcr &= ~CFCR_SBREAK; break; case TIOCSDTR: (void) dcamctl(dev, MCR_DTR | MCR_RTS, DMBIS); break; case TIOCCDTR: (void) dcamctl(dev, MCR_DTR | MCR_RTS, DMBIC); break; case TIOCMSET: (void) dcamctl(dev, *(int *)data, DMSET); break; case TIOCMBIS: (void) dcamctl(dev, *(int *)data, DMBIS); break; case TIOCMBIC: (void) dcamctl(dev, *(int *)data, DMBIC); break; case TIOCMGET: *(int *)data = dcamctl(dev, 0, DMGET); break; case TIOCGFLAGS: { int bits = 0; if (dcasoftCAR & (1 << unit)) bits |= TIOCFLAG_SOFTCAR; if (tp->t_cflag & CLOCAL) bits |= TIOCFLAG_CLOCAL; *(int *)data = bits; break; } case TIOCSFLAGS: { int userbits; error = suser(p->p_ucred, &p->p_acflag); if (error) return (EPERM); userbits = *(int *)data; if ((userbits & TIOCFLAG_SOFTCAR) || (unit == dcaconsole)) dcasoftCAR |= (1 << unit); if (userbits & TIOCFLAG_CLOCAL) tp->t_cflag |= CLOCAL; break; } default: return (ENOTTY); } return (0); } int dcaparam(tp, t) register struct tty *tp; register struct termios *t; { register struct dcadevice *dca; register int cfcr, cflag = t->c_cflag; int unit = UNIT(tp->t_dev); int ospeed = ttspeedtab(t->c_ospeed, dcaspeedtab); int s; /* check requested parameters */ if (ospeed < 0 || (t->c_ispeed && t->c_ispeed != t->c_ospeed)) return (EINVAL); dca = dca_addr[unit]; switch (cflag & CSIZE) { case CS5: cfcr = CFCR_5BITS; break; case CS6: cfcr = CFCR_6BITS; break; case CS7: cfcr = CFCR_7BITS; break; case CS8: cfcr = CFCR_8BITS; break; } if (cflag & PARENB) { cfcr |= CFCR_PENAB; if ((cflag & PARODD) == 0) cfcr |= CFCR_PEVEN; } if (cflag & CSTOPB) cfcr |= CFCR_STOPB; s = spltty(); if (ospeed == 0) (void) dcamctl(unit, 0, DMSET); /* hang up line */ /* * Set the FIFO threshold based on the recieve speed, if we * are changing it. */ if (tp->t_ispeed != t->c_ispeed) { if (dca_hasfifo & (1 << unit)) dca->dca_fifo = FIFO_ENABLE | (t->c_ispeed <= 1200 ? FIFO_TRIGGER_1 : FIFO_TRIGGER_14); } if (ospeed != 0) { dca->dca_cfcr |= CFCR_DLAB; dca->dca_data = ospeed & 0xFF; dca->dca_ier = ospeed >> 8; dca->dca_cfcr = cfcr; } else dca->dca_cfcr = cfcr; /* and copy to tty */ tp->t_ispeed = t->c_ispeed; tp->t_ospeed = t->c_ospeed; tp->t_cflag = cflag; dca->dca_ier = IER_ERXRDY | IER_ETXRDY | IER_ERLS | IER_EMSC; dca->dca_mcr |= MCR_IEN; splx(s); return (0); } void dcastart(tp) register struct tty *tp; { register struct dcadevice *dca; int s, unit, c; unit = UNIT(tp->t_dev); dca = dca_addr[unit]; s = spltty(); if (tp->t_state & (TS_TIMEOUT|TS_TTSTOP)) goto out; if (tp->t_outq.c_cc <= tp->t_lowat) { if (tp->t_state & TS_ASLEEP) { tp->t_state &= ~TS_ASLEEP; wakeup((caddr_t)&tp->t_outq); } if (tp->t_outq.c_cc == 0) goto out; selwakeup(&tp->t_wsel); } if (dca->dca_lsr & LSR_TXRDY) { tp->t_state |= TS_BUSY; if (dca_hasfifo & (1 << unit)) { for (c = 0; c < 16 && tp->t_outq.c_cc; ++c) dca->dca_data = getc(&tp->t_outq); #ifdef DEBUG if (c > 16) fifoout[0]++; else fifoout[c]++; #endif } else dca->dca_data = getc(&tp->t_outq); } out: splx(s); } /* * Stop output on a line. */ /*ARGSUSED*/ int dcastop(tp, flag) register struct tty *tp; int flag; { register int s; s = spltty(); if (tp->t_state & TS_BUSY) if ((tp->t_state & TS_TTSTOP) == 0) tp->t_state |= TS_FLUSH; splx(s); } dcamctl(dev, bits, how) dev_t dev; int bits, how; { register struct dcadevice *dca; register int unit; int s; unit = UNIT(dev); dca = dca_addr[unit]; /* * Always make sure MCR_IEN is set (unless setting to 0) */ #ifdef KGDB if (how == DMSET && kgdb_dev == makedev(dcamajor, unit)) bits |= MCR_IEN; else #endif if (how == DMBIS || (how == DMSET && bits)) bits |= MCR_IEN; else if (how == DMBIC) bits &= ~MCR_IEN; s = spltty(); switch (how) { case DMSET: dca->dca_mcr = bits; break; case DMBIS: dca->dca_mcr |= bits; break; case DMBIC: dca->dca_mcr &= ~bits; break; case DMGET: bits = dca->dca_msr; break; } (void) splx(s); return (bits); } /* * Following are all routines needed for DCA to act as console */ #include void dcacnprobe(cp) struct consdev *cp; { int unit; /* locate the major number */ for (dcamajor = 0; dcamajor < nchrdev; dcamajor++) if (cdevsw[dcamajor].d_open == dcaopen) break; /* XXX: ick */ unit = CONUNIT; #ifdef hp300 dca_addr[CONUNIT] = (struct dcadevice *) sctova(CONSCODE); /* make sure hardware exists */ if (badaddr((short *)dca_addr[unit])) { cp->cn_pri = CN_DEAD; return; } #endif #ifdef hp700 dca_addr[CONUNIT] = CONPORT; #endif /* initialize required fields */ cp->cn_dev = makedev(dcamajor, unit); #ifdef hp300 switch (dca_addr[unit]->dca_id) { case DCAID0: case DCAID1: cp->cn_pri = CN_NORMAL; break; case DCAREMID0: case DCAREMID1: cp->cn_pri = CN_REMOTE; break; default: cp->cn_pri = CN_DEAD; break; } #endif #ifdef hp700 cp->cn_pri = CN_NORMAL; #endif /* * If dcaconsole is initialized, raise our priority. */ if (dcaconsole == unit) cp->cn_pri = CN_REMOTE; #ifdef KGDB if (major(kgdb_dev) == 1) /* XXX */ kgdb_dev = makedev(dcamajor, minor(kgdb_dev)); #endif } void dcacninit(cp) struct consdev *cp; { int unit = UNIT(cp->cn_dev); dcainit(unit, dcadefaultrate); dcaconsole = unit; dcaconsinit = 1; } dcainit(unit, rate) int unit, rate; { register struct dcadevice *dca; int s; short stat; #ifdef lint stat = unit; if (stat) return; #endif dca = dca_addr[unit]; s = splhigh(); #ifdef hp300 dca->dca_reset = 0xFF; DELAY(100); dca->dca_ic = IC_IE; #endif dca->dca_cfcr = CFCR_DLAB; rate = ttspeedtab(rate, dcaspeedtab); dca->dca_data = rate & 0xFF; dca->dca_ier = rate >> 8; dca->dca_cfcr = CFCR_8BITS; dca->dca_ier = IER_ERXRDY | IER_ETXRDY; dca->dca_fifo = FIFO_ENABLE|FIFO_RCV_RST|FIFO_XMT_RST|FIFO_TRIGGER_14; dca->dca_mcr |= MCR_IEN; DELAY(100); stat = dca->dca_iir; splx(s); } int dcacngetc(dev) dev_t dev; { register struct dcadevice *dca = dca_addr[UNIT(dev)]; register u_char stat; int c, s; #ifdef lint stat = dev; if (stat) return (0); #endif s = splhigh(); while (((stat = dca->dca_lsr) & LSR_RXRDY) == 0) ; c = dca->dca_data; stat = dca->dca_iir; splx(s); return (c); } /* * Console kernel output character routine. */ void dcacnputc(dev, c) dev_t dev; register int c; { register struct dcadevice *dca = dca_addr[UNIT(dev)]; register int timo; register u_char stat; int s = splhigh(); #ifdef lint stat = dev; if (stat) return; #endif if (dcaconsinit == 0) { (void) dcainit(UNIT(dev), dcadefaultrate); dcaconsinit = 1; } /* wait for any pending transmission to finish */ timo = 50000; while (((stat = dca->dca_lsr) & LSR_TXRDY) == 0 && --timo) ; dca->dca_data = c; /* wait for this transmission to complete */ timo = 1500000; while (((stat = dca->dca_lsr) & LSR_TXRDY) == 0 && --timo) ; /* * If the "normal" interface was busy transfering a character * we must let our interrupt through to keep things moving. * Otherwise, we clear the interrupt that we have caused. */ if ((dca_tty[UNIT(dev)]->t_state & TS_BUSY) == 0) stat = dca->dca_iir; splx(s); } #endif