xref: /freebsd/sys/dev/uart/uart_dev_z8530.c (revision af23369a6deaaeb612ab266eb88b8bb8d560c322)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2003 Marcel Moolenaar
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/bus.h>
35 #include <sys/conf.h>
36 #include <machine/bus.h>
37 
38 #include <dev/uart/uart.h>
39 #include <dev/uart/uart_cpu.h>
40 #include <dev/uart/uart_bus.h>
41 
42 #include <dev/ic/z8530.h>
43 
44 #include "uart_if.h"
45 
46 #define	DEFAULT_RCLK	307200
47 
48 /* Hack! */
49 #ifdef __powerpc__
50 #define	UART_PCLK	0
51 #else
52 #define	UART_PCLK	MCB2_PCLK
53 #endif
54 
55 /* Multiplexed I/O. */
56 static __inline void
57 uart_setmreg(struct uart_bas *bas, int reg, int val)
58 {
59 
60 	uart_setreg(bas, REG_CTRL, reg);
61 	uart_barrier(bas);
62 	uart_setreg(bas, REG_CTRL, val);
63 }
64 
65 static __inline uint8_t
66 uart_getmreg(struct uart_bas *bas, int reg)
67 {
68 
69 	uart_setreg(bas, REG_CTRL, reg);
70 	uart_barrier(bas);
71 	return (uart_getreg(bas, REG_CTRL));
72 }
73 
74 static int
75 z8530_divisor(int rclk, int baudrate)
76 {
77 	int act_baud, divisor, error;
78 
79 	if (baudrate == 0)
80 		return (-1);
81 
82 	divisor = (rclk + baudrate) / (baudrate << 1) - 2;
83 	if (divisor < 0 || divisor >= 65536)
84 		return (-1);
85 	act_baud = rclk / 2 / (divisor + 2);
86 
87 	/* 10 times error in percent: */
88 	error = ((act_baud - baudrate) * 2000 / baudrate + 1) >> 1;
89 
90 	/* 3.0% maximum error tolerance: */
91 	if (error < -30 || error > 30)
92 		return (-1);
93 
94 	return (divisor);
95 }
96 
97 static int
98 z8530_param(struct uart_bas *bas, int baudrate, int databits, int stopbits,
99     int parity, uint8_t *tpcp)
100 {
101 	int divisor;
102 	uint8_t mpm, rpc, tpc;
103 
104 	rpc = RPC_RXE;
105 	mpm = MPM_CM16;
106 	tpc = TPC_TXE | (*tpcp & (TPC_DTR | TPC_RTS));
107 
108 	if (databits >= 8) {
109 		rpc |= RPC_RB8;
110 		tpc |= TPC_TB8;
111 	} else if (databits == 7) {
112 		rpc |= RPC_RB7;
113 		tpc |= TPC_TB7;
114 	} else if (databits == 6) {
115 		rpc |= RPC_RB6;
116 		tpc |= TPC_TB6;
117 	} else {
118 		rpc |= RPC_RB5;
119 		tpc |= TPC_TB5;
120 	}
121 	mpm |= (stopbits > 1) ? MPM_SB2 : MPM_SB1;
122 	switch (parity) {
123 	case UART_PARITY_EVEN:	mpm |= MPM_PE | MPM_EVEN; break;
124 	case UART_PARITY_NONE:	break;
125 	case UART_PARITY_ODD:	mpm |= MPM_PE; break;
126 	default:		return (EINVAL);
127 	}
128 
129 	if (baudrate > 0) {
130 		divisor = z8530_divisor(bas->rclk, baudrate);
131 		if (divisor == -1)
132 			return (EINVAL);
133 	} else
134 		divisor = -1;
135 
136 	uart_setmreg(bas, WR_MCB2, UART_PCLK);
137 	uart_barrier(bas);
138 
139 	if (divisor >= 0) {
140 		uart_setmreg(bas, WR_TCL, divisor & 0xff);
141 		uart_barrier(bas);
142 		uart_setmreg(bas, WR_TCH, (divisor >> 8) & 0xff);
143 		uart_barrier(bas);
144 	}
145 
146 	uart_setmreg(bas, WR_RPC, rpc);
147 	uart_barrier(bas);
148 	uart_setmreg(bas, WR_MPM, mpm);
149 	uart_barrier(bas);
150 	uart_setmreg(bas, WR_TPC, tpc);
151 	uart_barrier(bas);
152 	uart_setmreg(bas, WR_MCB2, UART_PCLK | MCB2_BRGE);
153 	uart_barrier(bas);
154 	*tpcp = tpc;
155 	return (0);
156 }
157 
158 static int
159 z8530_setup(struct uart_bas *bas, int baudrate, int databits, int stopbits,
160     int parity)
161 {
162 	uint8_t tpc;
163 
164 	if (bas->rclk == 0)
165 		bas->rclk = DEFAULT_RCLK;
166 
167 	/* Assume we don't need to perform a full hardware reset. */
168 	switch (bas->chan) {
169 	case 1:
170 		uart_setmreg(bas, WR_MIC, MIC_NV | MIC_CRA);
171 		break;
172 	case 2:
173 		uart_setmreg(bas, WR_MIC, MIC_NV | MIC_CRB);
174 		break;
175 	}
176 	uart_barrier(bas);
177 	/* Set clock sources. */
178 	uart_setmreg(bas, WR_CMC, CMC_RC_BRG | CMC_TC_BRG);
179 	uart_setmreg(bas, WR_MCB2, UART_PCLK);
180 	uart_barrier(bas);
181 	/* Set data encoding. */
182 	uart_setmreg(bas, WR_MCB1, MCB1_NRZ);
183 	uart_barrier(bas);
184 
185 	tpc = TPC_DTR | TPC_RTS;
186 	z8530_param(bas, baudrate, databits, stopbits, parity, &tpc);
187 	return (int)tpc;
188 }
189 
190 /*
191  * Low-level UART interface.
192  */
193 static int z8530_probe(struct uart_bas *bas);
194 static void z8530_init(struct uart_bas *bas, int, int, int, int);
195 static void z8530_term(struct uart_bas *bas);
196 static void z8530_putc(struct uart_bas *bas, int);
197 static int z8530_rxready(struct uart_bas *bas);
198 static int z8530_getc(struct uart_bas *bas, struct mtx *);
199 
200 static struct uart_ops uart_z8530_ops = {
201 	.probe = z8530_probe,
202 	.init = z8530_init,
203 	.term = z8530_term,
204 	.putc = z8530_putc,
205 	.rxready = z8530_rxready,
206 	.getc = z8530_getc,
207 };
208 
209 static int
210 z8530_probe(struct uart_bas *bas)
211 {
212 
213 	return (0);
214 }
215 
216 static void
217 z8530_init(struct uart_bas *bas, int baudrate, int databits, int stopbits,
218     int parity)
219 {
220 
221 	z8530_setup(bas, baudrate, databits, stopbits, parity);
222 }
223 
224 static void
225 z8530_term(struct uart_bas *bas)
226 {
227 }
228 
229 static void
230 z8530_putc(struct uart_bas *bas, int c)
231 {
232 
233 	while (!(uart_getreg(bas, REG_CTRL) & BES_TXE))
234 		;
235 	uart_setreg(bas, REG_DATA, c);
236 	uart_barrier(bas);
237 }
238 
239 static int
240 z8530_rxready(struct uart_bas *bas)
241 {
242 
243 	return ((uart_getreg(bas, REG_CTRL) & BES_RXA) != 0 ? 1 : 0);
244 }
245 
246 static int
247 z8530_getc(struct uart_bas *bas, struct mtx *hwmtx)
248 {
249 	int c;
250 
251 	uart_lock(hwmtx);
252 
253 	while (!(uart_getreg(bas, REG_CTRL) & BES_RXA)) {
254 		uart_unlock(hwmtx);
255 		DELAY(10);
256 		uart_lock(hwmtx);
257 	}
258 
259 	c = uart_getreg(bas, REG_DATA);
260 
261 	uart_unlock(hwmtx);
262 
263 	return (c);
264 }
265 
266 /*
267  * High-level UART interface.
268  */
269 struct z8530_softc {
270 	struct uart_softc base;
271 	uint8_t	tpc;
272 	uint8_t	txidle;
273 };
274 
275 static int z8530_bus_attach(struct uart_softc *);
276 static int z8530_bus_detach(struct uart_softc *);
277 static int z8530_bus_flush(struct uart_softc *, int);
278 static int z8530_bus_getsig(struct uart_softc *);
279 static int z8530_bus_ioctl(struct uart_softc *, int, intptr_t);
280 static int z8530_bus_ipend(struct uart_softc *);
281 static int z8530_bus_param(struct uart_softc *, int, int, int, int);
282 static int z8530_bus_probe(struct uart_softc *);
283 static int z8530_bus_receive(struct uart_softc *);
284 static int z8530_bus_setsig(struct uart_softc *, int);
285 static int z8530_bus_transmit(struct uart_softc *);
286 static void z8530_bus_grab(struct uart_softc *);
287 static void z8530_bus_ungrab(struct uart_softc *);
288 
289 static kobj_method_t z8530_methods[] = {
290 	KOBJMETHOD(uart_attach,		z8530_bus_attach),
291 	KOBJMETHOD(uart_detach,		z8530_bus_detach),
292 	KOBJMETHOD(uart_flush,		z8530_bus_flush),
293 	KOBJMETHOD(uart_getsig,		z8530_bus_getsig),
294 	KOBJMETHOD(uart_ioctl,		z8530_bus_ioctl),
295 	KOBJMETHOD(uart_ipend,		z8530_bus_ipend),
296 	KOBJMETHOD(uart_param,		z8530_bus_param),
297 	KOBJMETHOD(uart_probe,		z8530_bus_probe),
298 	KOBJMETHOD(uart_receive,	z8530_bus_receive),
299 	KOBJMETHOD(uart_setsig,		z8530_bus_setsig),
300 	KOBJMETHOD(uart_transmit,	z8530_bus_transmit),
301 	KOBJMETHOD(uart_grab,		z8530_bus_grab),
302 	KOBJMETHOD(uart_ungrab,		z8530_bus_ungrab),
303 	{ 0, 0 }
304 };
305 
306 struct uart_class uart_z8530_class = {
307 	"z8530",
308 	z8530_methods,
309 	sizeof(struct z8530_softc),
310 	.uc_ops = &uart_z8530_ops,
311 	.uc_range = 2,
312 	.uc_rclk = DEFAULT_RCLK,
313 	.uc_rshift = 0
314 };
315 
316 #define	SIGCHG(c, i, s, d)				\
317 	if (c) {					\
318 		i |= (i & s) ? s : s | d;		\
319 	} else {					\
320 		i = (i & s) ? (i & ~s) | d : i;		\
321 	}
322 
323 static int
324 z8530_bus_attach(struct uart_softc *sc)
325 {
326 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
327 	struct uart_bas *bas;
328 	struct uart_devinfo *di;
329 
330 	bas = &sc->sc_bas;
331 	if (sc->sc_sysdev != NULL) {
332 		di = sc->sc_sysdev;
333 		z8530->tpc = TPC_DTR|TPC_RTS;
334 		z8530_param(bas, di->baudrate, di->databits, di->stopbits,
335 		    di->parity, &z8530->tpc);
336 	} else {
337 		z8530->tpc = z8530_setup(bas, 9600, 8, 1, UART_PARITY_NONE);
338 		z8530->tpc &= ~(TPC_DTR|TPC_RTS);
339 	}
340 	z8530->txidle = 1;	/* Report SER_INT_TXIDLE. */
341 
342 	(void)z8530_bus_getsig(sc);
343 
344 	uart_setmreg(bas, WR_IC, IC_BRK | IC_CTS | IC_DCD);
345 	uart_barrier(bas);
346 	uart_setmreg(bas, WR_IDT, IDT_XIE | IDT_TIE | IDT_RIA);
347 	uart_barrier(bas);
348 	uart_setmreg(bas, WR_IV, 0);
349 	uart_barrier(bas);
350 	uart_setmreg(bas, WR_TPC, z8530->tpc);
351 	uart_barrier(bas);
352 	uart_setmreg(bas, WR_MIC, MIC_NV | MIC_MIE);
353 	uart_barrier(bas);
354 	return (0);
355 }
356 
357 static int
358 z8530_bus_detach(struct uart_softc *sc)
359 {
360 
361 	return (0);
362 }
363 
364 static int
365 z8530_bus_flush(struct uart_softc *sc, int what)
366 {
367 
368 	return (0);
369 }
370 
371 static int
372 z8530_bus_getsig(struct uart_softc *sc)
373 {
374 	uint32_t new, old, sig;
375 	uint8_t bes;
376 
377 	do {
378 		old = sc->sc_hwsig;
379 		sig = old;
380 		uart_lock(sc->sc_hwmtx);
381 		bes = uart_getmreg(&sc->sc_bas, RR_BES);
382 		uart_unlock(sc->sc_hwmtx);
383 		SIGCHG(bes & BES_CTS, sig, SER_CTS, SER_DCTS);
384 		SIGCHG(bes & BES_DCD, sig, SER_DCD, SER_DDCD);
385 		SIGCHG(bes & BES_SYNC, sig, SER_DSR, SER_DDSR);
386 		new = sig & ~SER_MASK_DELTA;
387 	} while (!atomic_cmpset_32(&sc->sc_hwsig, old, new));
388 	return (sig);
389 }
390 
391 static int
392 z8530_bus_ioctl(struct uart_softc *sc, int request, intptr_t data)
393 {
394 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
395 	struct uart_bas *bas;
396 	int baudrate, divisor, error;
397 
398 	bas = &sc->sc_bas;
399 	error = 0;
400 	uart_lock(sc->sc_hwmtx);
401 	switch (request) {
402 	case UART_IOCTL_BREAK:
403 		if (data)
404 			z8530->tpc |= TPC_BRK;
405 		else
406 			z8530->tpc &= ~TPC_BRK;
407 		uart_setmreg(bas, WR_TPC, z8530->tpc);
408 		uart_barrier(bas);
409 		break;
410 	case UART_IOCTL_BAUD:
411 		divisor = uart_getmreg(bas, RR_TCH);
412 		divisor = (divisor << 8) | uart_getmreg(bas, RR_TCL);
413 		baudrate = bas->rclk / 2 / (divisor + 2);
414 		*(int*)data = baudrate;
415 		break;
416 	default:
417 		error = EINVAL;
418 		break;
419 	}
420 	uart_unlock(sc->sc_hwmtx);
421 	return (error);
422 }
423 
424 static int
425 z8530_bus_ipend(struct uart_softc *sc)
426 {
427 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
428 	struct uart_bas *bas;
429 	int ipend;
430 	uint32_t sig;
431 	uint8_t bes, ip, iv, src;
432 
433 	bas = &sc->sc_bas;
434 	ipend = 0;
435 
436 	uart_lock(sc->sc_hwmtx);
437 	switch (bas->chan) {
438 	case 1:
439 		ip = uart_getmreg(bas, RR_IP);
440 		break;
441 	case 2:	/* XXX hack!!! */
442 		iv = uart_getmreg(bas, RR_IV) & 0x0E;
443 		switch (iv) {
444 		case IV_TEB:	ip = IP_TIA; break;
445 		case IV_XSB:	ip = IP_SIA; break;
446 		case IV_RAB:	ip = IP_RIA; break;
447 		default:	ip = 0; break;
448 		}
449 		break;
450 	default:
451 		ip = 0;
452 		break;
453 	}
454 
455 	if (ip & IP_RIA)
456 		ipend |= SER_INT_RXREADY;
457 
458 	if (ip & IP_TIA) {
459 		uart_setreg(bas, REG_CTRL, CR_RSTTXI);
460 		uart_barrier(bas);
461 		if (z8530->txidle) {
462 			ipend |= SER_INT_TXIDLE;
463 			z8530->txidle = 0;	/* Mask SER_INT_TXIDLE. */
464 		}
465 	}
466 
467 	if (ip & IP_SIA) {
468 		uart_setreg(bas, REG_CTRL, CR_RSTXSI);
469 		uart_barrier(bas);
470 		bes = uart_getmreg(bas, RR_BES);
471 		if (bes & BES_BRK)
472 			ipend |= SER_INT_BREAK;
473 		sig = sc->sc_hwsig;
474 		SIGCHG(bes & BES_CTS, sig, SER_CTS, SER_DCTS);
475 		SIGCHG(bes & BES_DCD, sig, SER_DCD, SER_DDCD);
476 		SIGCHG(bes & BES_SYNC, sig, SER_DSR, SER_DDSR);
477 		if (sig & SER_MASK_DELTA)
478 			ipend |= SER_INT_SIGCHG;
479 		src = uart_getmreg(bas, RR_SRC);
480 		if (src & SRC_OVR) {
481 			uart_setreg(bas, REG_CTRL, CR_RSTERR);
482 			uart_barrier(bas);
483 			ipend |= SER_INT_OVERRUN;
484 		}
485 	}
486 
487 	if (ipend) {
488 		uart_setreg(bas, REG_CTRL, CR_RSTIUS);
489 		uart_barrier(bas);
490 	}
491 
492 	uart_unlock(sc->sc_hwmtx);
493 
494 	return (ipend);
495 }
496 
497 static int
498 z8530_bus_param(struct uart_softc *sc, int baudrate, int databits,
499     int stopbits, int parity)
500 {
501 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
502 	int error;
503 
504 	uart_lock(sc->sc_hwmtx);
505 	error = z8530_param(&sc->sc_bas, baudrate, databits, stopbits, parity,
506 	    &z8530->tpc);
507 	uart_unlock(sc->sc_hwmtx);
508 	return (error);
509 }
510 
511 static int
512 z8530_bus_probe(struct uart_softc *sc)
513 {
514 	char buf[80];
515 	int error;
516 	char ch;
517 
518 	error = z8530_probe(&sc->sc_bas);
519 	if (error)
520 		return (error);
521 
522 	sc->sc_rxfifosz = 3;
523 	sc->sc_txfifosz = 1;
524 
525 	ch = sc->sc_bas.chan - 1 + 'A';
526 
527 	snprintf(buf, sizeof(buf), "z8530, channel %c", ch);
528 	device_set_desc_copy(sc->sc_dev, buf);
529 	return (0);
530 }
531 
532 static int
533 z8530_bus_receive(struct uart_softc *sc)
534 {
535 	struct uart_bas *bas;
536 	int xc;
537 	uint8_t bes, src;
538 
539 	bas = &sc->sc_bas;
540 	uart_lock(sc->sc_hwmtx);
541 	bes = uart_getmreg(bas, RR_BES);
542 	while (bes & BES_RXA) {
543 		if (uart_rx_full(sc)) {
544 			sc->sc_rxbuf[sc->sc_rxput] = UART_STAT_OVERRUN;
545 			break;
546 		}
547 		xc = uart_getreg(bas, REG_DATA);
548 		uart_barrier(bas);
549 		src = uart_getmreg(bas, RR_SRC);
550 		if (src & SRC_FE)
551 			xc |= UART_STAT_FRAMERR;
552 		if (src & SRC_PE)
553 			xc |= UART_STAT_PARERR;
554 		if (src & SRC_OVR)
555 			xc |= UART_STAT_OVERRUN;
556 		uart_rx_put(sc, xc);
557 		if (src & (SRC_FE | SRC_PE | SRC_OVR)) {
558 			uart_setreg(bas, REG_CTRL, CR_RSTERR);
559 			uart_barrier(bas);
560 		}
561 		bes = uart_getmreg(bas, RR_BES);
562 	}
563 	/* Discard everything left in the Rx FIFO. */
564 	while (bes & BES_RXA) {
565 		(void)uart_getreg(bas, REG_DATA);
566 		uart_barrier(bas);
567 		src = uart_getmreg(bas, RR_SRC);
568 		if (src & (SRC_FE | SRC_PE | SRC_OVR)) {
569 			uart_setreg(bas, REG_CTRL, CR_RSTERR);
570 			uart_barrier(bas);
571 		}
572 		bes = uart_getmreg(bas, RR_BES);
573 	}
574 	uart_unlock(sc->sc_hwmtx);
575 	return (0);
576 }
577 
578 static int
579 z8530_bus_setsig(struct uart_softc *sc, int sig)
580 {
581 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
582 	struct uart_bas *bas;
583 	uint32_t new, old;
584 
585 	bas = &sc->sc_bas;
586 	do {
587 		old = sc->sc_hwsig;
588 		new = old;
589 		if (sig & SER_DDTR) {
590 			SIGCHG(sig & SER_DTR, new, SER_DTR,
591 			    SER_DDTR);
592 		}
593 		if (sig & SER_DRTS) {
594 			SIGCHG(sig & SER_RTS, new, SER_RTS,
595 			    SER_DRTS);
596 		}
597 	} while (!atomic_cmpset_32(&sc->sc_hwsig, old, new));
598 
599 	uart_lock(sc->sc_hwmtx);
600 	if (new & SER_DTR)
601 		z8530->tpc |= TPC_DTR;
602 	else
603 		z8530->tpc &= ~TPC_DTR;
604 	if (new & SER_RTS)
605 		z8530->tpc |= TPC_RTS;
606 	else
607 		z8530->tpc &= ~TPC_RTS;
608 	uart_setmreg(bas, WR_TPC, z8530->tpc);
609 	uart_barrier(bas);
610 	uart_unlock(sc->sc_hwmtx);
611 	return (0);
612 }
613 
614 static int
615 z8530_bus_transmit(struct uart_softc *sc)
616 {
617 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
618 	struct uart_bas *bas;
619 
620 	bas = &sc->sc_bas;
621 	uart_lock(sc->sc_hwmtx);
622 	while (!(uart_getmreg(bas, RR_BES) & BES_TXE))
623 		;
624 	uart_setreg(bas, REG_DATA, sc->sc_txbuf[0]);
625 	uart_barrier(bas);
626 	sc->sc_txbusy = 1;
627 	z8530->txidle = 1;	/* Report SER_INT_TXIDLE again. */
628 	uart_unlock(sc->sc_hwmtx);
629 	return (0);
630 }
631 
632 static void
633 z8530_bus_grab(struct uart_softc *sc)
634 {
635 	struct uart_bas *bas;
636 
637 	bas = &sc->sc_bas;
638 	uart_lock(sc->sc_hwmtx);
639 	uart_setmreg(bas, WR_IDT, IDT_XIE | IDT_TIE);
640 	uart_barrier(bas);
641 	uart_unlock(sc->sc_hwmtx);
642 }
643 
644 static void
645 z8530_bus_ungrab(struct uart_softc *sc)
646 {
647 	struct uart_bas *bas;
648 
649 	bas = &sc->sc_bas;
650 	uart_lock(sc->sc_hwmtx);
651 	uart_setmreg(bas, WR_IDT, IDT_XIE | IDT_TIE | IDT_RIA);
652 	uart_barrier(bas);
653 	uart_unlock(sc->sc_hwmtx);
654 }
655