aic7xxx_seeprom.c revision 1.6 1 /* $NetBSD: aic7xxx_seeprom.c,v 1.6 2001/11/13 13:14:34 lukem Exp $ */
2
3 /*
4 * Product specific probe and attach routines for:
5 * 3940, 2940, aic7895, aic7890, aic7880,
6 * aic7870, aic7860 and aic7850 SCSI controllers
7 *
8 * These are the SEEPROM-reading functions only. They were split off from
9 * the PCI-specific support by Jason R. Thorpe <thorpej (at) netbsd.org>.
10 *
11 * Copyright (c) 1994, 1995, 1996, 1997, 1998, 1999, 2000 Justin T. Gibbs.
12 * All rights reserved.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions, and the following disclaimer,
19 * without modification.
20 * 2. The name of the author may not be used to endorse or promote products
21 * derived from this software without specific prior written permission.
22 *
23 * Alternatively, this software may be distributed under the terms of the
24 * the GNU Public License ("GPL").
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
30 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * $FreeBSD: src/sys/dev/aic7xxx/ahc_pci.c,v 1.27 2000/01/10 01:47:51 gibbs Exp
39 $
40 */
41
42 #include <sys/cdefs.h>
43 __KERNEL_RCSID(0, "$NetBSD: aic7xxx_seeprom.c,v 1.6 2001/11/13 13:14:34 lukem Exp $");
44
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/malloc.h>
48 #include <sys/kernel.h>
49 #include <sys/queue.h>
50 #include <sys/device.h>
51 #include <sys/reboot.h> /* for AB_* needed by bootverbose */
52
53 #include <machine/bus.h>
54 #include <machine/intr.h>
55
56 #include <dev/scsipi/scsi_all.h>
57 #include <dev/scsipi/scsipi_all.h>
58 #include <dev/scsipi/scsiconf.h>
59
60 #include <dev/microcode/aic7xxx/aic7xxx_reg.h>
61 #include <dev/ic/aic7xxxvar.h>
62 #include <dev/ic/smc93cx6var.h>
63
64 static void configure_termination(struct ahc_softc *,
65 struct seeprom_descriptor *, u_int, u_int *);
66
67 static void ahc_new_term_detect(struct ahc_softc *, int *, int *, int *,
68 int *, int *);
69 static void aic787X_cable_detect(struct ahc_softc *, int *, int *, int *,
70 int *);
71 static void aic785X_cable_detect(struct ahc_softc *, int *, int *, int *);
72 static int acquire_seeprom(struct ahc_softc *, struct seeprom_descriptor *);
73 static void release_seeprom(struct seeprom_descriptor *);
74 static void write_brdctl(struct ahc_softc *, u_int8_t);
75 static u_int8_t read_brdctl(struct ahc_softc *);
76
77 /*
78 * Check the external port logic for a serial eeprom
79 * and termination/cable detection contrls.
80 */
81 void
82 check_extport(struct ahc_softc *ahc, u_int *sxfrctl1)
83 {
84 struct seeprom_descriptor sd;
85 struct seeprom_config sc;
86 u_int scsi_conf;
87 u_int adapter_control;
88 int have_seeprom;
89 int have_autoterm;
90
91 sd.sd_tag = ahc->tag;
92 sd.sd_bsh = ahc->bsh;
93 sd.sd_control_offset = SEECTL;
94 sd.sd_status_offset = SEECTL;
95 sd.sd_dataout_offset = SEECTL;
96
97 /*
98 * For some multi-channel devices, the c46 is simply too
99 * small to work. For the other controller types, we can
100 * get our information from either SEEPROM type. Set the
101 * type to start our probe with accordingly.
102 */
103 if (ahc->flags & AHC_LARGE_SEEPROM)
104 sd.sd_chip = C56_66;
105 else
106 sd.sd_chip = C46;
107
108 sd.sd_MS = SEEMS;
109 sd.sd_RDY = SEERDY;
110 sd.sd_CS = SEECS;
111 sd.sd_CK = SEECK;
112 sd.sd_DO = SEEDO;
113 sd.sd_DI = SEEDI;
114
115 have_seeprom = acquire_seeprom(ahc, &sd);
116 if (have_seeprom) {
117
118 if (bootverbose)
119 printf("%s: Reading SEEPROM...", ahc_name(ahc));
120
121 for (;;) {
122 bus_size_t start_addr;
123
124 start_addr = 32 * (ahc->channel - 'A');
125
126 have_seeprom = read_seeprom(&sd, (u_int16_t *)&sc,
127 start_addr, sizeof(sc)/2);
128
129 if (have_seeprom) {
130 /* Check checksum */
131 int i;
132 int maxaddr;
133 u_int32_t checksum;
134 u_int16_t *scarray;
135
136 maxaddr = (sizeof(sc)/2) - 1;
137 checksum = 0;
138 scarray = (u_int16_t *)≻
139
140 for (i = 0; i < maxaddr; i++)
141 checksum = checksum + scarray[i];
142 if (checksum == 0
143 || (checksum & 0xFFFF) != sc.checksum) {
144 if (bootverbose && sd.sd_chip == C56_66)
145 printf ("checksum error\n");
146 have_seeprom = 0;
147 } else {
148 if (bootverbose)
149 printf("done.\n");
150 break;
151 }
152 }
153
154 if (sd.sd_chip == C56_66)
155 break;
156 sd.sd_chip = C56_66;
157 }
158 }
159
160 if (!have_seeprom) {
161 if (bootverbose)
162 printf("%s: No SEEPROM available\n", ahc_name(ahc));
163 ahc->flags |= AHC_USEDEFAULTS;
164 } else {
165 /*
166 * Put the data we've collected down into SRAM
167 * where ahc_init will find it.
168 */
169 int i;
170 int max_targ = sc.max_targets & CFMAXTARG;
171 u_int16_t discenable;
172 u_int16_t ultraenb;
173
174 discenable = 0;
175 ultraenb = 0;
176 if ((sc.adapter_control & CFULTRAEN) != 0) {
177 /*
178 * Determine if this adapter has a "newstyle"
179 * SEEPROM format.
180 */
181 for (i = 0; i < max_targ; i++) {
182 if ((sc.device_flags[i] & CFSYNCHISULTRA) != 0){
183 ahc->flags |= AHC_NEWEEPROM_FMT;
184 break;
185 }
186 }
187 }
188
189 for (i = 0; i < max_targ; i++) {
190 u_int scsirate;
191 u_int16_t target_mask;
192
193 target_mask = 0x01 << i;
194 if (sc.device_flags[i] & CFDISC)
195 discenable |= target_mask;
196 if ((ahc->flags & AHC_NEWEEPROM_FMT) != 0) {
197 if ((sc.device_flags[i] & CFSYNCHISULTRA) != 0)
198 ultraenb |= target_mask;
199 } else if ((sc.adapter_control & CFULTRAEN) != 0) {
200 ultraenb |= target_mask;
201 }
202 if ((sc.device_flags[i] & CFXFER) == 0x04
203 && (ultraenb & target_mask) != 0) {
204 /* Treat 10MHz as a non-ultra speed */
205 sc.device_flags[i] &= ~CFXFER;
206 ultraenb &= ~target_mask;
207 }
208 if ((ahc->features & AHC_ULTRA2) != 0) {
209 u_int offset;
210
211 if (sc.device_flags[i] & CFSYNCH)
212 offset = MAX_OFFSET_ULTRA2;
213 else
214 offset = 0;
215 ahc_outb(ahc, TARG_OFFSET + i, offset);
216
217 scsirate = (sc.device_flags[i] & CFXFER)
218 | ((ultraenb & target_mask)
219 ? 0x8 : 0x0);
220 if (sc.device_flags[i] & CFWIDEB)
221 scsirate |= WIDEXFER;
222 } else {
223 scsirate = (sc.device_flags[i] & CFXFER) << 4;
224 if (sc.device_flags[i] & CFSYNCH)
225 scsirate |= SOFS;
226 if (sc.device_flags[i] & CFWIDEB)
227 scsirate |= WIDEXFER;
228 }
229 ahc_outb(ahc, TARG_SCSIRATE + i, scsirate);
230 }
231 ahc->our_id = sc.brtime_id & CFSCSIID;
232
233 scsi_conf = (ahc->our_id & 0x7);
234 if (sc.adapter_control & CFSPARITY)
235 scsi_conf |= ENSPCHK;
236 if (sc.adapter_control & CFRESETB)
237 scsi_conf |= RESET_SCSI;
238
239 if (sc.bios_control & CFEXTEND)
240 ahc->flags |= AHC_EXTENDED_TRANS_A;
241 if (ahc->features & AHC_ULTRA
242 && (ahc->flags & AHC_NEWEEPROM_FMT) == 0) {
243 /* Should we enable Ultra mode? */
244 if (!(sc.adapter_control & CFULTRAEN))
245 /* Treat us as a non-ultra card */
246 ultraenb = 0;
247 }
248 /* Set SCSICONF info */
249 ahc_outb(ahc, SCSICONF, scsi_conf);
250 ahc_outb(ahc, DISC_DSB, ~(discenable & 0xff));
251 ahc_outb(ahc, DISC_DSB + 1, ~((discenable >> 8) & 0xff));
252 ahc_outb(ahc, ULTRA_ENB, ultraenb & 0xff);
253 ahc_outb(ahc, ULTRA_ENB + 1, (ultraenb >> 8) & 0xff);
254 }
255
256 /*
257 * Cards that have the external logic necessary to talk to
258 * a SEEPROM, are almost certain to have the remaining logic
259 * necessary for auto-termination control. This assumption
260 * hasn't failed yet...
261 */
262 have_autoterm = have_seeprom;
263 if (have_seeprom)
264 adapter_control = sc.adapter_control;
265 else
266 adapter_control = CFAUTOTERM;
267
268 /*
269 * Some low-cost chips have SEEPROM and auto-term control built
270 * in, instead of using a GAL. They can tell us directly
271 * if the termination logic is enabled.
272 */
273 if ((ahc->features & AHC_SPIOCAP) != 0) {
274 if ((ahc_inb(ahc, SPIOCAP) & SSPIOCPS) != 0)
275 have_autoterm = TRUE;
276 else
277 have_autoterm = FALSE;
278 }
279
280 if (have_autoterm)
281 configure_termination(ahc, &sd, adapter_control, sxfrctl1);
282
283 release_seeprom(&sd);
284 }
285
286 static void
287 configure_termination(struct ahc_softc *ahc,
288 struct seeprom_descriptor *sd,
289 u_int adapter_control,
290 u_int *sxfrctl1)
291 {
292 u_int8_t brddat;
293
294 brddat = 0;
295
296 /*
297 * Update the settings in sxfrctl1 to match the
298 * termination settings
299 */
300 *sxfrctl1 = 0;
301
302 /*
303 * SEECS must be on for the GALS to latch
304 * the data properly. Be sure to leave MS
305 * on or we will release the seeprom.
306 */
307 SEEPROM_OUTB(sd, sd->sd_MS | sd->sd_CS);
308 if ((adapter_control & CFAUTOTERM) != 0
309 || (ahc->features & AHC_NEW_TERMCTL) != 0) {
310 int internal50_present;
311 int internal68_present;
312 int externalcable_present;
313 int eeprom_present;
314 int enableSEC_low;
315 int enableSEC_high;
316 int enablePRI_low;
317 int enablePRI_high;
318
319 enableSEC_low = 0;
320 enableSEC_high = 0;
321 enablePRI_low = 0;
322 enablePRI_high = 0;
323 if ((ahc->features & AHC_NEW_TERMCTL) != 0) {
324 ahc_new_term_detect(ahc, &enableSEC_low,
325 &enableSEC_high,
326 &enablePRI_low,
327 &enablePRI_high,
328 &eeprom_present);
329 if ((adapter_control & CFSEAUTOTERM) == 0) {
330 if (bootverbose)
331 printf("%s: Manual SE Termination\n",
332 ahc_name(ahc));
333 enableSEC_low = (adapter_control & CFSTERM);
334 enableSEC_high = (adapter_control & CFWSTERM);
335 }
336 if ((adapter_control & CFAUTOTERM) == 0) {
337 if (bootverbose)
338 printf("%s: Manual LVD Termination\n",
339 ahc_name(ahc));
340 enablePRI_low = enablePRI_high =
341 (adapter_control & CFLVDSTERM);
342 }
343 /* Make the table calculations below happy */
344 internal50_present = 0;
345 internal68_present = 1;
346 externalcable_present = 1;
347 } else if ((ahc->features & AHC_SPIOCAP) != 0) {
348 aic785X_cable_detect(ahc, &internal50_present,
349 &externalcable_present,
350 &eeprom_present);
351 } else {
352 aic787X_cable_detect(ahc, &internal50_present,
353 &internal68_present,
354 &externalcable_present,
355 &eeprom_present);
356 }
357
358 if ((ahc->features & AHC_WIDE) == 0)
359 internal68_present = 0;
360
361 if (bootverbose) {
362 if ((ahc->features & AHC_ULTRA2) == 0) {
363 printf("%s: internal 50 cable %s present, "
364 "internal 68 cable %s present\n",
365 ahc_name(ahc),
366 internal50_present ? "is":"not",
367 internal68_present ? "is":"not");
368
369 printf("%s: external cable %s present\n",
370 ahc_name(ahc),
371 externalcable_present ? "is":"not");
372 }
373 printf("%s: BIOS eeprom %s present\n",
374 ahc_name(ahc), eeprom_present ? "is" : "not");
375 }
376
377 if ((ahc->flags & AHC_INT50_SPEEDFLEX) != 0) {
378 /*
379 * The 50 pin connector is a separate bus,
380 * so force it to always be terminated.
381 * In the future, perform current sensing
382 * to determine if we are in the middle of
383 * a properly terminated bus.
384 */
385 internal50_present = 0;
386 }
387
388 /*
389 * Now set the termination based on what
390 * we found.
391 * Flash Enable = BRDDAT7
392 * Secondary High Term Enable = BRDDAT6
393 * Secondary Low Term Enable = BRDDAT5 (7890)
394 * Primary High Term Enable = BRDDAT4 (7890)
395 */
396 if ((ahc->features & AHC_ULTRA2) == 0
397 && (internal50_present != 0)
398 && (internal68_present != 0)
399 && (externalcable_present != 0)) {
400 printf("%s: Illegal cable configuration!!. "
401 "Only two connectors on the "
402 "adapter may be used at a "
403 "time!\n", ahc_name(ahc));
404 }
405
406 if ((ahc->features & AHC_WIDE) != 0
407 && ((externalcable_present == 0)
408 || (internal68_present == 0)
409 || (enableSEC_high != 0))) {
410 brddat |= BRDDAT6;
411 if (bootverbose) {
412 if ((ahc->flags & AHC_INT50_SPEEDFLEX) != 0)
413 printf("%s: 68 pin termination "
414 "Enabled\n", ahc_name(ahc));
415 else
416 printf("%s: %sHigh byte termination "
417 "Enabled\n", ahc_name(ahc),
418 enableSEC_high ? "Secondary "
419 : "");
420 }
421 }
422
423 if (((internal50_present ? 1 : 0)
424 + (internal68_present ? 1 : 0)
425 + (externalcable_present ? 1 : 0)) <= 1
426 || (enableSEC_low != 0)) {
427 if ((ahc->features & AHC_ULTRA2) != 0)
428 brddat |= BRDDAT5;
429 else
430 *sxfrctl1 |= STPWEN;
431 if (bootverbose) {
432 if ((ahc->flags & AHC_INT50_SPEEDFLEX) != 0)
433 printf("%s: 50 pin termination "
434 "Enabled\n", ahc_name(ahc));
435 else
436 printf("%s: %sLow byte termination "
437 "Enabled\n", ahc_name(ahc),
438 enableSEC_low ? "Secondary "
439 : "");
440 }
441 }
442
443 if (enablePRI_low != 0) {
444 *sxfrctl1 |= STPWEN;
445 if (bootverbose)
446 printf("%s: Primary Low Byte termination "
447 "Enabled\n", ahc_name(ahc));
448 }
449
450 /*
451 * Setup STPWEN before setting up the rest of
452 * the termination per the tech note on the U160 cards.
453 */
454 ahc_outb(ahc, SXFRCTL1, *sxfrctl1);
455
456 if (enablePRI_high != 0) {
457 brddat |= BRDDAT4;
458 if (bootverbose)
459 printf("%s: Primary High Byte "
460 "termination Enabled\n",
461 ahc_name(ahc));
462 }
463
464 write_brdctl(ahc, brddat);
465
466 } else {
467 if ((adapter_control & CFSTERM) != 0) {
468 *sxfrctl1 |= STPWEN;
469
470 if (bootverbose)
471 printf("%s: %sLow byte termination Enabled\n",
472 ahc_name(ahc),
473 (ahc->features & AHC_ULTRA2) ? "Primary "
474 : "");
475 }
476
477 if ((adapter_control & CFWSTERM) != 0) {
478 brddat |= BRDDAT6;
479 if (bootverbose)
480 printf("%s: %sHigh byte termination Enabled\n",
481 ahc_name(ahc),
482 (ahc->features & AHC_ULTRA2)
483 ? "Secondary " : "");
484 }
485
486 /*
487 * Setup STPWEN before setting up the rest of
488 * the termination per the tech note on the U160 cards.
489 */
490 ahc_outb(ahc, SXFRCTL1, *sxfrctl1);
491
492 write_brdctl(ahc, brddat);
493 }
494 SEEPROM_OUTB(sd, sd->sd_MS); /* Clear CS */
495 }
496
497 static void
498 ahc_new_term_detect(struct ahc_softc *ahc, int *enableSEC_low,
499 int *enableSEC_high, int *enablePRI_low,
500 int *enablePRI_high, int *eeprom_present)
501 {
502 u_int8_t brdctl;
503
504 /*
505 * BRDDAT7 = Eeprom
506 * BRDDAT6 = Enable Secondary High Byte termination
507 * BRDDAT5 = Enable Secondary Low Byte termination
508 * BRDDAT4 = Enable Primary high byte termination
509 * BRDDAT3 = Enable Primary low byte termination
510 */
511 brdctl = read_brdctl(ahc);
512 *eeprom_present = brdctl & BRDDAT7;
513 *enableSEC_high = (brdctl & BRDDAT6);
514 *enableSEC_low = (brdctl & BRDDAT5);
515 *enablePRI_high = (brdctl & BRDDAT4);
516 *enablePRI_low = (brdctl & BRDDAT3);
517 }
518
519 static void
520 aic787X_cable_detect(struct ahc_softc *ahc, int *internal50_present,
521 int *internal68_present, int *externalcable_present,
522 int *eeprom_present)
523 {
524 u_int8_t brdctl;
525
526 /*
527 * First read the status of our cables.
528 * Set the rom bank to 0 since the
529 * bank setting serves as a multiplexor
530 * for the cable detection logic.
531 * BRDDAT5 controls the bank switch.
532 */
533 write_brdctl(ahc, 0);
534
535 /*
536 * Now read the state of the internal
537 * connectors. BRDDAT6 is INT50 and
538 * BRDDAT7 is INT68.
539 */
540 brdctl = read_brdctl(ahc);
541 *internal50_present = !(brdctl & BRDDAT6);
542 *internal68_present = !(brdctl & BRDDAT7);
543
544 /*
545 * Set the rom bank to 1 and determine
546 * the other signals.
547 */
548 write_brdctl(ahc, BRDDAT5);
549
550 /*
551 * Now read the state of the external
552 * connectors. BRDDAT6 is EXT68 and
553 * BRDDAT7 is EPROMPS.
554 */
555 brdctl = read_brdctl(ahc);
556 *externalcable_present = !(brdctl & BRDDAT6);
557 *eeprom_present = brdctl & BRDDAT7;
558 }
559
560 static void
561 aic785X_cable_detect(struct ahc_softc *ahc, int *internal50_present,
562 int *externalcable_present, int *eeprom_present)
563 {
564 u_int8_t brdctl;
565
566 ahc_outb(ahc, BRDCTL, BRDRW|BRDCS);
567 ahc_outb(ahc, BRDCTL, 0);
568 brdctl = ahc_inb(ahc, BRDCTL);
569 *internal50_present = !(brdctl & BRDDAT5);
570 *externalcable_present = !(brdctl & BRDDAT6);
571
572 *eeprom_present = (ahc_inb(ahc, SPIOCAP) & EEPROM) != 0;
573 }
574
575 static int
576 acquire_seeprom(struct ahc_softc *ahc, struct seeprom_descriptor *sd)
577 {
578 int wait;
579
580 if ((ahc->features & AHC_SPIOCAP) != 0
581 && (ahc_inb(ahc, SPIOCAP) & SEEPROM) == 0)
582 return (0);
583
584 /*
585 * Request access of the memory port. When access is
586 * granted, SEERDY will go high. We use a 100 msec
587 * timeout which should be near 100 msecs more than
588 * is needed. Reason: after the chip reset, there
589 * should be no contention.
590 */
591 SEEPROM_OUTB(sd, sd->sd_MS);
592 wait = 100; /* 100 msec timeout */
593 while (--wait && ((SEEPROM_STATUS_INB(sd) & sd->sd_RDY) == 0)) {
594 DELAY(1000); /* delay 1 msec */
595 }
596 if ((SEEPROM_STATUS_INB(sd) & sd->sd_RDY) == 0) {
597 SEEPROM_OUTB(sd, 0);
598 return (0);
599 }
600 return(1);
601 }
602
603 static void
604 release_seeprom(struct seeprom_descriptor *sd)
605 {
606 /* Release access to the memory port and the serial EEPROM. */
607 SEEPROM_OUTB(sd, 0);
608 }
609
610 static void
611 write_brdctl(struct ahc_softc *ahc, u_int8_t value)
612 {
613 u_int8_t brdctl;
614
615 if ((ahc->chip & AHC_CHIPID_MASK) == AHC_AIC7895) {
616 brdctl = BRDSTB;
617 if (ahc->channel == 'B')
618 brdctl |= BRDCS;
619 } else if ((ahc->features & AHC_ULTRA2) != 0) {
620 brdctl = 0;
621 } else {
622 brdctl = BRDSTB|BRDCS;
623 }
624 ahc_outb(ahc, BRDCTL, brdctl);
625 DELAY(20);
626 brdctl |= value;
627 ahc_outb(ahc, BRDCTL, brdctl);
628 DELAY(20);
629 if ((ahc->features & AHC_ULTRA2) != 0)
630 brdctl |= BRDSTB_ULTRA2;
631 else
632 brdctl &= ~BRDSTB;
633 ahc_outb(ahc, BRDCTL, brdctl);
634 DELAY(20);
635 if ((ahc->features & AHC_ULTRA2) != 0)
636 brdctl = 0;
637 else
638 brdctl &= ~BRDCS;
639 ahc_outb(ahc, BRDCTL, brdctl);
640 }
641
642 static u_int8_t
643 read_brdctl(struct ahc_softc *ahc)
644 {
645 u_int8_t brdctl;
646 u_int8_t value;
647
648 if ((ahc->chip & AHC_CHIPID_MASK) == AHC_AIC7895) {
649 brdctl = BRDRW;
650 if (ahc->channel == 'B')
651 brdctl |= BRDCS;
652 } else if ((ahc->features & AHC_ULTRA2) != 0) {
653 brdctl = BRDRW_ULTRA2;
654 } else {
655 brdctl = BRDRW|BRDCS;
656 }
657 ahc_outb(ahc, BRDCTL, brdctl);
658 DELAY(20);
659 value = ahc_inb(ahc, BRDCTL);
660 ahc_outb(ahc, BRDCTL, 0);
661 return (value);
662 }
663