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BSD 4_4_Lite2 release
[unix-history] / usr / src / sys / hp / dev / dca.c
/*
* 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 8.3 (Berkeley) 1/9/95
*/
#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, 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.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ioctl.h>
#include <sys/proc.h>
#include <sys/tty.h>
#include <sys/conf.h>
#include <sys/file.h>
#include <sys/uio.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <hp/dev/device.h>
#include <hp/dev/dcareg.h>
#include <machine/cpu.h>
#ifdef hp300
#include <hp300/hp300/isr.h>
#endif
#ifdef hp700
#include <machine/asp.h>
#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 <machine/remote-sl.h>
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);
}
return (1);
}
/* ARGSUSED */
#ifdef __STDC__
dcaopen(dev_t dev, int flag, int mode, struct proc *p)
#else
dcaopen(dev, flag, mode, p)
dev_t dev;
int flag, mode;
struct proc *p;
#endif
{
register struct tty *tp;
register int unit;
int error = 0;
unit = UNIT(dev);
if (unit >= NDCA || (dca_active & (1 << unit)) == 0)
return (ENXIO);
tp = &dca_tty[unit];
tp->t_oproc = dcastart;
tp->t_param = dcaparam;
tp->t_dev = dev;
if ((tp->t_state & TS_ISOPEN) == 0) {
tp->t_state |= TS_WOPEN;
ttychars(tp);
if (tp->t_ispeed == 0) {
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;
}
dcaparam(tp, &tp->t_termios);
ttsetwater(tp);
} else if (tp->t_state&TS_XCLUDE && p->p_ucred->cr_uid != 0)
return (EBUSY);
(void) dcamctl(dev, MCR_DTR | MCR_RTS, DMSET);
if ((dcasoftCAR & (1 << unit)) || (dcamctl(dev, 0, DMGET) & MSR_DCD))
tp->t_state |= TS_CARR_ON;
(void) spltty();
while ((flag&O_NONBLOCK) == 0 && (tp->t_cflag&CLOCAL) == 0 &&
(tp->t_state & TS_CARR_ON) == 0) {
tp->t_state |= TS_WOPEN;
if (error = ttysleep(tp, (caddr_t)&tp->t_rawq, TTIPRI | PCATCH,
ttopen, 0))
break;
}
(void) spl0();
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*/
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;
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);
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 || tp->t_state&TS_WOPEN ||
(tp->t_state&TS_ISOPEN) == 0)
(void) dcamctl(dev, 0, DMSET);
ttyclose(tp);
return (0);
}
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);
}
dcawrite(dev, uio, flag)
dev_t dev;
struct uio *uio;
int flag;
{
int unit = UNIT(dev);
register struct tty *tp = &dca_tty[unit];
extern struct tty *constty;
/*
* (XXX) We disallow virtual consoles if the physical console is
* a serial port. This is in case there is a display attached that
* is not the console. In that situation we don't need/want the X
* server taking over the console.
*/
if (constty && unit == dcaconsole)
constty = NULL;
return ((*linesw[tp->t_line].l_write)(tp, uio, flag));
}
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];
while (1) {
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;
}
}
}
dcaioctl(dev, cmd, data, flag, p)
dev_t dev;
u_long 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);
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;
default:
return (ENOTTY);
}
return (0);
}
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);
/* check requested parameters */
if (ospeed < 0 || (t->c_ispeed && t->c_ispeed != t->c_ospeed))
return (EINVAL);
/* and copy to tty */
tp->t_ispeed = t->c_ispeed;
tp->t_ospeed = t->c_ospeed;
tp->t_cflag = cflag;
dca = dca_addr[unit];
dca->dca_ier = IER_ERXRDY | IER_ETXRDY | IER_ERLS | IER_EMSC;
#ifdef hp700
dca->dca_mcr |= MCR_IEN;
#endif
if (ospeed == 0) {
(void) dcamctl(unit, 0, DMSET); /* hang up line */
return (0);
}
dca->dca_cfcr |= CFCR_DLAB;
dca->dca_data = ospeed & 0xFF;
dca->dca_ier = ospeed >> 8;
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;
dca->dca_cfcr = cfcr;
if (dca_hasfifo & (1 << unit))
dca->dca_fifo = FIFO_ENABLE | FIFO_TRIGGER_14;
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);
}
selwakeup(&tp->t_wsel);
}
if (tp->t_outq.c_cc == 0)
goto out;
if (dca->dca_lsr & LSR_TXRDY) {
c = getc(&tp->t_outq);
tp->t_state |= TS_BUSY;
dca->dca_data = c;
if (dca_hasfifo & (1 << unit)) {
for (c = 1; 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
}
}
out:
splx(s);
}
/*
* Stop output on a line.
*/
/*ARGSUSED*/
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];
#ifdef hp700
/*
* 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;
#endif
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 <hp/dev/cons.h>
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);
cp->cn_tp = &dca_tty[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
}
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;
#ifdef hp700
dca->dca_mcr |= MCR_IEN;
#endif
dca->dca_fifo = FIFO_ENABLE|FIFO_RCV_RST|FIFO_XMT_RST|FIFO_TRIGGER_14;
DELAY(100);
stat = dca->dca_iir;
splx(s);
}
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.
*/
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
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.