xref: /freebsd/sys/dev/uart/uart_dev_z8530.c (revision 2008043f386721d58158e37e0d7e50df8095942d)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
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 #include <sys/param.h>
31 #include <sys/systm.h>
32 #include <sys/bus.h>
33 #include <sys/conf.h>
34 #include <machine/bus.h>
35 
36 #include <dev/uart/uart.h>
37 #include <dev/uart/uart_cpu.h>
38 #include <dev/uart/uart_bus.h>
39 
40 #include <dev/ic/z8530.h>
41 
42 #include "uart_if.h"
43 
44 #define	DEFAULT_RCLK	307200
45 
46 /* Hack! */
47 #ifdef __powerpc__
48 #define	UART_PCLK	0
49 #else
50 #define	UART_PCLK	MCB2_PCLK
51 #endif
52 
53 /* Multiplexed I/O. */
54 static __inline void
55 uart_setmreg(struct uart_bas *bas, int reg, int val)
56 {
57 
58 	uart_setreg(bas, REG_CTRL, reg);
59 	uart_barrier(bas);
60 	uart_setreg(bas, REG_CTRL, val);
61 }
62 
63 static __inline uint8_t
64 uart_getmreg(struct uart_bas *bas, int reg)
65 {
66 
67 	uart_setreg(bas, REG_CTRL, reg);
68 	uart_barrier(bas);
69 	return (uart_getreg(bas, REG_CTRL));
70 }
71 
72 static int
73 z8530_divisor(int rclk, int baudrate)
74 {
75 	int act_baud, divisor, error;
76 
77 	if (baudrate == 0)
78 		return (-1);
79 
80 	divisor = (rclk + baudrate) / (baudrate << 1) - 2;
81 	if (divisor < 0 || divisor >= 65536)
82 		return (-1);
83 	act_baud = rclk / 2 / (divisor + 2);
84 
85 	/* 10 times error in percent: */
86 	error = ((act_baud - baudrate) * 2000 / baudrate + 1) >> 1;
87 
88 	/* 3.0% maximum error tolerance: */
89 	if (error < -30 || error > 30)
90 		return (-1);
91 
92 	return (divisor);
93 }
94 
95 static int
96 z8530_param(struct uart_bas *bas, int baudrate, int databits, int stopbits,
97     int parity, uint8_t *tpcp)
98 {
99 	int divisor;
100 	uint8_t mpm, rpc, tpc;
101 
102 	rpc = RPC_RXE;
103 	mpm = MPM_CM16;
104 	tpc = TPC_TXE | (*tpcp & (TPC_DTR | TPC_RTS));
105 
106 	if (databits >= 8) {
107 		rpc |= RPC_RB8;
108 		tpc |= TPC_TB8;
109 	} else if (databits == 7) {
110 		rpc |= RPC_RB7;
111 		tpc |= TPC_TB7;
112 	} else if (databits == 6) {
113 		rpc |= RPC_RB6;
114 		tpc |= TPC_TB6;
115 	} else {
116 		rpc |= RPC_RB5;
117 		tpc |= TPC_TB5;
118 	}
119 	mpm |= (stopbits > 1) ? MPM_SB2 : MPM_SB1;
120 	switch (parity) {
121 	case UART_PARITY_EVEN:	mpm |= MPM_PE | MPM_EVEN; break;
122 	case UART_PARITY_NONE:	break;
123 	case UART_PARITY_ODD:	mpm |= MPM_PE; break;
124 	default:		return (EINVAL);
125 	}
126 
127 	if (baudrate > 0) {
128 		divisor = z8530_divisor(bas->rclk, baudrate);
129 		if (divisor == -1)
130 			return (EINVAL);
131 	} else
132 		divisor = -1;
133 
134 	uart_setmreg(bas, WR_MCB2, UART_PCLK);
135 	uart_barrier(bas);
136 
137 	if (divisor >= 0) {
138 		uart_setmreg(bas, WR_TCL, divisor & 0xff);
139 		uart_barrier(bas);
140 		uart_setmreg(bas, WR_TCH, (divisor >> 8) & 0xff);
141 		uart_barrier(bas);
142 	}
143 
144 	uart_setmreg(bas, WR_RPC, rpc);
145 	uart_barrier(bas);
146 	uart_setmreg(bas, WR_MPM, mpm);
147 	uart_barrier(bas);
148 	uart_setmreg(bas, WR_TPC, tpc);
149 	uart_barrier(bas);
150 	uart_setmreg(bas, WR_MCB2, UART_PCLK | MCB2_BRGE);
151 	uart_barrier(bas);
152 	*tpcp = tpc;
153 	return (0);
154 }
155 
156 static int
157 z8530_setup(struct uart_bas *bas, int baudrate, int databits, int stopbits,
158     int parity)
159 {
160 	uint8_t tpc;
161 
162 	if (bas->rclk == 0)
163 		bas->rclk = DEFAULT_RCLK;
164 
165 	/* Assume we don't need to perform a full hardware reset. */
166 	switch (bas->chan) {
167 	case 1:
168 		uart_setmreg(bas, WR_MIC, MIC_NV | MIC_CRA);
169 		break;
170 	case 2:
171 		uart_setmreg(bas, WR_MIC, MIC_NV | MIC_CRB);
172 		break;
173 	}
174 	uart_barrier(bas);
175 	/* Set clock sources. */
176 	uart_setmreg(bas, WR_CMC, CMC_RC_BRG | CMC_TC_BRG);
177 	uart_setmreg(bas, WR_MCB2, UART_PCLK);
178 	uart_barrier(bas);
179 	/* Set data encoding. */
180 	uart_setmreg(bas, WR_MCB1, MCB1_NRZ);
181 	uart_barrier(bas);
182 
183 	tpc = TPC_DTR | TPC_RTS;
184 	z8530_param(bas, baudrate, databits, stopbits, parity, &tpc);
185 	return (int)tpc;
186 }
187 
188 /*
189  * Low-level UART interface.
190  */
191 static int z8530_probe(struct uart_bas *bas);
192 static void z8530_init(struct uart_bas *bas, int, int, int, int);
193 static void z8530_term(struct uart_bas *bas);
194 static void z8530_putc(struct uart_bas *bas, int);
195 static int z8530_rxready(struct uart_bas *bas);
196 static int z8530_getc(struct uart_bas *bas, struct mtx *);
197 
198 static struct uart_ops uart_z8530_ops = {
199 	.probe = z8530_probe,
200 	.init = z8530_init,
201 	.term = z8530_term,
202 	.putc = z8530_putc,
203 	.rxready = z8530_rxready,
204 	.getc = z8530_getc,
205 };
206 
207 static int
208 z8530_probe(struct uart_bas *bas)
209 {
210 
211 	return (0);
212 }
213 
214 static void
215 z8530_init(struct uart_bas *bas, int baudrate, int databits, int stopbits,
216     int parity)
217 {
218 
219 	z8530_setup(bas, baudrate, databits, stopbits, parity);
220 }
221 
222 static void
223 z8530_term(struct uart_bas *bas)
224 {
225 }
226 
227 static void
228 z8530_putc(struct uart_bas *bas, int c)
229 {
230 
231 	while (!(uart_getreg(bas, REG_CTRL) & BES_TXE))
232 		;
233 	uart_setreg(bas, REG_DATA, c);
234 	uart_barrier(bas);
235 }
236 
237 static int
238 z8530_rxready(struct uart_bas *bas)
239 {
240 
241 	return ((uart_getreg(bas, REG_CTRL) & BES_RXA) != 0 ? 1 : 0);
242 }
243 
244 static int
245 z8530_getc(struct uart_bas *bas, struct mtx *hwmtx)
246 {
247 	int c;
248 
249 	uart_lock(hwmtx);
250 
251 	while (!(uart_getreg(bas, REG_CTRL) & BES_RXA)) {
252 		uart_unlock(hwmtx);
253 		DELAY(10);
254 		uart_lock(hwmtx);
255 	}
256 
257 	c = uart_getreg(bas, REG_DATA);
258 
259 	uart_unlock(hwmtx);
260 
261 	return (c);
262 }
263 
264 /*
265  * High-level UART interface.
266  */
267 struct z8530_softc {
268 	struct uart_softc base;
269 	uint8_t	tpc;
270 	uint8_t	txidle;
271 };
272 
273 static int z8530_bus_attach(struct uart_softc *);
274 static int z8530_bus_detach(struct uart_softc *);
275 static int z8530_bus_flush(struct uart_softc *, int);
276 static int z8530_bus_getsig(struct uart_softc *);
277 static int z8530_bus_ioctl(struct uart_softc *, int, intptr_t);
278 static int z8530_bus_ipend(struct uart_softc *);
279 static int z8530_bus_param(struct uart_softc *, int, int, int, int);
280 static int z8530_bus_probe(struct uart_softc *);
281 static int z8530_bus_receive(struct uart_softc *);
282 static int z8530_bus_setsig(struct uart_softc *, int);
283 static int z8530_bus_transmit(struct uart_softc *);
284 static void z8530_bus_grab(struct uart_softc *);
285 static void z8530_bus_ungrab(struct uart_softc *);
286 
287 static kobj_method_t z8530_methods[] = {
288 	KOBJMETHOD(uart_attach,		z8530_bus_attach),
289 	KOBJMETHOD(uart_detach,		z8530_bus_detach),
290 	KOBJMETHOD(uart_flush,		z8530_bus_flush),
291 	KOBJMETHOD(uart_getsig,		z8530_bus_getsig),
292 	KOBJMETHOD(uart_ioctl,		z8530_bus_ioctl),
293 	KOBJMETHOD(uart_ipend,		z8530_bus_ipend),
294 	KOBJMETHOD(uart_param,		z8530_bus_param),
295 	KOBJMETHOD(uart_probe,		z8530_bus_probe),
296 	KOBJMETHOD(uart_receive,	z8530_bus_receive),
297 	KOBJMETHOD(uart_setsig,		z8530_bus_setsig),
298 	KOBJMETHOD(uart_transmit,	z8530_bus_transmit),
299 	KOBJMETHOD(uart_grab,		z8530_bus_grab),
300 	KOBJMETHOD(uart_ungrab,		z8530_bus_ungrab),
301 	{ 0, 0 }
302 };
303 
304 struct uart_class uart_z8530_class = {
305 	"z8530",
306 	z8530_methods,
307 	sizeof(struct z8530_softc),
308 	.uc_ops = &uart_z8530_ops,
309 	.uc_range = 2,
310 	.uc_rclk = DEFAULT_RCLK,
311 	.uc_rshift = 0
312 };
313 
314 #define	SIGCHG(c, i, s, d)				\
315 	if (c) {					\
316 		i |= (i & s) ? s : s | d;		\
317 	} else {					\
318 		i = (i & s) ? (i & ~s) | d : i;		\
319 	}
320 
321 static int
322 z8530_bus_attach(struct uart_softc *sc)
323 {
324 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
325 	struct uart_bas *bas;
326 	struct uart_devinfo *di;
327 
328 	bas = &sc->sc_bas;
329 	if (sc->sc_sysdev != NULL) {
330 		di = sc->sc_sysdev;
331 		z8530->tpc = TPC_DTR|TPC_RTS;
332 		z8530_param(bas, di->baudrate, di->databits, di->stopbits,
333 		    di->parity, &z8530->tpc);
334 	} else {
335 		z8530->tpc = z8530_setup(bas, 9600, 8, 1, UART_PARITY_NONE);
336 		z8530->tpc &= ~(TPC_DTR|TPC_RTS);
337 	}
338 	z8530->txidle = 1;	/* Report SER_INT_TXIDLE. */
339 
340 	(void)z8530_bus_getsig(sc);
341 
342 	uart_setmreg(bas, WR_IC, IC_BRK | IC_CTS | IC_DCD);
343 	uart_barrier(bas);
344 	uart_setmreg(bas, WR_IDT, IDT_XIE | IDT_TIE | IDT_RIA);
345 	uart_barrier(bas);
346 	uart_setmreg(bas, WR_IV, 0);
347 	uart_barrier(bas);
348 	uart_setmreg(bas, WR_TPC, z8530->tpc);
349 	uart_barrier(bas);
350 	uart_setmreg(bas, WR_MIC, MIC_NV | MIC_MIE);
351 	uart_barrier(bas);
352 	return (0);
353 }
354 
355 static int
356 z8530_bus_detach(struct uart_softc *sc)
357 {
358 
359 	return (0);
360 }
361 
362 static int
363 z8530_bus_flush(struct uart_softc *sc, int what)
364 {
365 
366 	return (0);
367 }
368 
369 static int
370 z8530_bus_getsig(struct uart_softc *sc)
371 {
372 	uint32_t new, old, sig;
373 	uint8_t bes;
374 
375 	do {
376 		old = sc->sc_hwsig;
377 		sig = old;
378 		uart_lock(sc->sc_hwmtx);
379 		bes = uart_getmreg(&sc->sc_bas, RR_BES);
380 		uart_unlock(sc->sc_hwmtx);
381 		SIGCHG(bes & BES_CTS, sig, SER_CTS, SER_DCTS);
382 		SIGCHG(bes & BES_DCD, sig, SER_DCD, SER_DDCD);
383 		SIGCHG(bes & BES_SYNC, sig, SER_DSR, SER_DDSR);
384 		new = sig & ~SER_MASK_DELTA;
385 	} while (!atomic_cmpset_32(&sc->sc_hwsig, old, new));
386 	return (sig);
387 }
388 
389 static int
390 z8530_bus_ioctl(struct uart_softc *sc, int request, intptr_t data)
391 {
392 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
393 	struct uart_bas *bas;
394 	int baudrate, divisor, error;
395 
396 	bas = &sc->sc_bas;
397 	error = 0;
398 	uart_lock(sc->sc_hwmtx);
399 	switch (request) {
400 	case UART_IOCTL_BREAK:
401 		if (data)
402 			z8530->tpc |= TPC_BRK;
403 		else
404 			z8530->tpc &= ~TPC_BRK;
405 		uart_setmreg(bas, WR_TPC, z8530->tpc);
406 		uart_barrier(bas);
407 		break;
408 	case UART_IOCTL_BAUD:
409 		divisor = uart_getmreg(bas, RR_TCH);
410 		divisor = (divisor << 8) | uart_getmreg(bas, RR_TCL);
411 		baudrate = bas->rclk / 2 / (divisor + 2);
412 		*(int*)data = baudrate;
413 		break;
414 	default:
415 		error = EINVAL;
416 		break;
417 	}
418 	uart_unlock(sc->sc_hwmtx);
419 	return (error);
420 }
421 
422 static int
423 z8530_bus_ipend(struct uart_softc *sc)
424 {
425 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
426 	struct uart_bas *bas;
427 	int ipend;
428 	uint32_t sig;
429 	uint8_t bes, ip, iv, src;
430 
431 	bas = &sc->sc_bas;
432 	ipend = 0;
433 
434 	uart_lock(sc->sc_hwmtx);
435 	switch (bas->chan) {
436 	case 1:
437 		ip = uart_getmreg(bas, RR_IP);
438 		break;
439 	case 2:	/* XXX hack!!! */
440 		iv = uart_getmreg(bas, RR_IV) & 0x0E;
441 		switch (iv) {
442 		case IV_TEB:	ip = IP_TIA; break;
443 		case IV_XSB:	ip = IP_SIA; break;
444 		case IV_RAB:	ip = IP_RIA; break;
445 		default:	ip = 0; break;
446 		}
447 		break;
448 	default:
449 		ip = 0;
450 		break;
451 	}
452 
453 	if (ip & IP_RIA)
454 		ipend |= SER_INT_RXREADY;
455 
456 	if (ip & IP_TIA) {
457 		uart_setreg(bas, REG_CTRL, CR_RSTTXI);
458 		uart_barrier(bas);
459 		if (z8530->txidle) {
460 			ipend |= SER_INT_TXIDLE;
461 			z8530->txidle = 0;	/* Mask SER_INT_TXIDLE. */
462 		}
463 	}
464 
465 	if (ip & IP_SIA) {
466 		uart_setreg(bas, REG_CTRL, CR_RSTXSI);
467 		uart_barrier(bas);
468 		bes = uart_getmreg(bas, RR_BES);
469 		if (bes & BES_BRK)
470 			ipend |= SER_INT_BREAK;
471 		sig = sc->sc_hwsig;
472 		SIGCHG(bes & BES_CTS, sig, SER_CTS, SER_DCTS);
473 		SIGCHG(bes & BES_DCD, sig, SER_DCD, SER_DDCD);
474 		SIGCHG(bes & BES_SYNC, sig, SER_DSR, SER_DDSR);
475 		if (sig & SER_MASK_DELTA)
476 			ipend |= SER_INT_SIGCHG;
477 		src = uart_getmreg(bas, RR_SRC);
478 		if (src & SRC_OVR) {
479 			uart_setreg(bas, REG_CTRL, CR_RSTERR);
480 			uart_barrier(bas);
481 			ipend |= SER_INT_OVERRUN;
482 		}
483 	}
484 
485 	if (ipend) {
486 		uart_setreg(bas, REG_CTRL, CR_RSTIUS);
487 		uart_barrier(bas);
488 	}
489 
490 	uart_unlock(sc->sc_hwmtx);
491 
492 	return (ipend);
493 }
494 
495 static int
496 z8530_bus_param(struct uart_softc *sc, int baudrate, int databits,
497     int stopbits, int parity)
498 {
499 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
500 	int error;
501 
502 	uart_lock(sc->sc_hwmtx);
503 	error = z8530_param(&sc->sc_bas, baudrate, databits, stopbits, parity,
504 	    &z8530->tpc);
505 	uart_unlock(sc->sc_hwmtx);
506 	return (error);
507 }
508 
509 static int
510 z8530_bus_probe(struct uart_softc *sc)
511 {
512 	char buf[80];
513 	int error;
514 	char ch;
515 
516 	error = z8530_probe(&sc->sc_bas);
517 	if (error)
518 		return (error);
519 
520 	sc->sc_rxfifosz = 3;
521 	sc->sc_txfifosz = 1;
522 
523 	ch = sc->sc_bas.chan - 1 + 'A';
524 
525 	snprintf(buf, sizeof(buf), "z8530, channel %c", ch);
526 	device_set_desc_copy(sc->sc_dev, buf);
527 	return (0);
528 }
529 
530 static int
531 z8530_bus_receive(struct uart_softc *sc)
532 {
533 	struct uart_bas *bas;
534 	int xc;
535 	uint8_t bes, src;
536 
537 	bas = &sc->sc_bas;
538 	uart_lock(sc->sc_hwmtx);
539 	bes = uart_getmreg(bas, RR_BES);
540 	while (bes & BES_RXA) {
541 		if (uart_rx_full(sc)) {
542 			sc->sc_rxbuf[sc->sc_rxput] = UART_STAT_OVERRUN;
543 			break;
544 		}
545 		xc = uart_getreg(bas, REG_DATA);
546 		uart_barrier(bas);
547 		src = uart_getmreg(bas, RR_SRC);
548 		if (src & SRC_FE)
549 			xc |= UART_STAT_FRAMERR;
550 		if (src & SRC_PE)
551 			xc |= UART_STAT_PARERR;
552 		if (src & SRC_OVR)
553 			xc |= UART_STAT_OVERRUN;
554 		uart_rx_put(sc, xc);
555 		if (src & (SRC_FE | SRC_PE | SRC_OVR)) {
556 			uart_setreg(bas, REG_CTRL, CR_RSTERR);
557 			uart_barrier(bas);
558 		}
559 		bes = uart_getmreg(bas, RR_BES);
560 	}
561 	/* Discard everything left in the Rx FIFO. */
562 	while (bes & BES_RXA) {
563 		(void)uart_getreg(bas, REG_DATA);
564 		uart_barrier(bas);
565 		src = uart_getmreg(bas, RR_SRC);
566 		if (src & (SRC_FE | SRC_PE | SRC_OVR)) {
567 			uart_setreg(bas, REG_CTRL, CR_RSTERR);
568 			uart_barrier(bas);
569 		}
570 		bes = uart_getmreg(bas, RR_BES);
571 	}
572 	uart_unlock(sc->sc_hwmtx);
573 	return (0);
574 }
575 
576 static int
577 z8530_bus_setsig(struct uart_softc *sc, int sig)
578 {
579 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
580 	struct uart_bas *bas;
581 	uint32_t new, old;
582 
583 	bas = &sc->sc_bas;
584 	do {
585 		old = sc->sc_hwsig;
586 		new = old;
587 		if (sig & SER_DDTR) {
588 			SIGCHG(sig & SER_DTR, new, SER_DTR,
589 			    SER_DDTR);
590 		}
591 		if (sig & SER_DRTS) {
592 			SIGCHG(sig & SER_RTS, new, SER_RTS,
593 			    SER_DRTS);
594 		}
595 	} while (!atomic_cmpset_32(&sc->sc_hwsig, old, new));
596 
597 	uart_lock(sc->sc_hwmtx);
598 	if (new & SER_DTR)
599 		z8530->tpc |= TPC_DTR;
600 	else
601 		z8530->tpc &= ~TPC_DTR;
602 	if (new & SER_RTS)
603 		z8530->tpc |= TPC_RTS;
604 	else
605 		z8530->tpc &= ~TPC_RTS;
606 	uart_setmreg(bas, WR_TPC, z8530->tpc);
607 	uart_barrier(bas);
608 	uart_unlock(sc->sc_hwmtx);
609 	return (0);
610 }
611 
612 static int
613 z8530_bus_transmit(struct uart_softc *sc)
614 {
615 	struct z8530_softc *z8530 = (struct z8530_softc*)sc;
616 	struct uart_bas *bas;
617 
618 	bas = &sc->sc_bas;
619 	uart_lock(sc->sc_hwmtx);
620 	while (!(uart_getmreg(bas, RR_BES) & BES_TXE))
621 		;
622 	uart_setreg(bas, REG_DATA, sc->sc_txbuf[0]);
623 	uart_barrier(bas);
624 	sc->sc_txbusy = 1;
625 	z8530->txidle = 1;	/* Report SER_INT_TXIDLE again. */
626 	uart_unlock(sc->sc_hwmtx);
627 	return (0);
628 }
629 
630 static void
631 z8530_bus_grab(struct uart_softc *sc)
632 {
633 	struct uart_bas *bas;
634 
635 	bas = &sc->sc_bas;
636 	uart_lock(sc->sc_hwmtx);
637 	uart_setmreg(bas, WR_IDT, IDT_XIE | IDT_TIE);
638 	uart_barrier(bas);
639 	uart_unlock(sc->sc_hwmtx);
640 }
641 
642 static void
643 z8530_bus_ungrab(struct uart_softc *sc)
644 {
645 	struct uart_bas *bas;
646 
647 	bas = &sc->sc_bas;
648 	uart_lock(sc->sc_hwmtx);
649 	uart_setmreg(bas, WR_IDT, IDT_XIE | IDT_TIE | IDT_RIA);
650 	uart_barrier(bas);
651 	uart_unlock(sc->sc_hwmtx);
652 }
653