xref: /netbsd-src/sys/arch/mac68k/dev/sbc.c (revision fdecd6a253f999ae92b139670d9e15cc9df4497c)
1 /*	$NetBSD: sbc.c,v 1.28 1997/06/30 05:24:35 scottr Exp $	*/
2 
3 /*
4  * Copyright (C) 1996 Scott Reynolds.  All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. All advertising materials mentioning features or use of this software
15  *    must display the following acknowledgement:
16  *      This product includes software developed by Scott Reynolds for
17  *      the NetBSD Project.
18  * 4. The name of the author may not be used to endorse or promote products
19  *    derived from this software without specific prior written permission
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 /*
34  * This file contains only the machine-dependent parts of the mac68k
35  * NCR 5380 SCSI driver.  (Autoconfig stuff and PDMA functions.)
36  * The machine-independent parts are in ncr5380sbc.c
37  *
38  * Supported hardware includes:
39  * Macintosh II family 5380-based controller
40  *
41  * Credits, history:
42  *
43  * Scott Reynolds wrote this module, based on work by Allen Briggs
44  * (mac68k), Gordon W. Ross and David Jones (sun3), and Leo Weppelman
45  * (atari).  Thanks to Allen for supplying crucial interpretation of the
46  * NetBSD/mac68k 1.1 'ncrscsi' driver.  Also, Allen, Gordon, and Jason
47  * Thorpe all helped to refine this code, and were considerable sources
48  * of moral support.
49  */
50 
51 #include <sys/types.h>
52 #include <sys/param.h>
53 #include <sys/systm.h>
54 #include <sys/kernel.h>
55 #include <sys/errno.h>
56 #include <sys/device.h>
57 #include <sys/buf.h>
58 #include <sys/proc.h>
59 #include <sys/user.h>
60 
61 #include <scsi/scsi_all.h>
62 #include <scsi/scsi_debug.h>
63 #include <scsi/scsiconf.h>
64 
65 #include <dev/ic/ncr5380reg.h>
66 #include <dev/ic/ncr5380var.h>
67 
68 #include <machine/cpu.h>
69 #include <machine/viareg.h>
70 
71 #include "sbcreg.h"
72 #include "sbcvar.h"
73 
74 int	sbc_debug = 0 /* | SBC_DB_INTR | SBC_DB_DMA */;
75 int	sbc_link_flags = 0 /* | SDEV_DB2 */;
76 int	sbc_options = 0 /* | SBC_PDMA */;
77 
78 static	void	sbc_minphys __P((struct buf *bp));
79 
80 struct scsi_adapter	sbc_ops = {
81 	ncr5380_scsi_cmd,		/* scsi_cmd()		*/
82 	sbc_minphys,			/* scsi_minphys()	*/
83 	NULL,				/* open_target_lu()	*/
84 	NULL,				/* close_target_lu()	*/
85 };
86 
87 /* This is copied from julian's bt driver */
88 /* "so we have a default dev struct for our link struct." */
89 struct scsi_device sbc_dev = {
90 	NULL,		/* Use default error handler.	    */
91 	NULL,		/* Use default start handler.		*/
92 	NULL,		/* Use default async handler.	    */
93 	NULL,		/* Use default "done" routine.	    */
94 };
95 
96 struct cfdriver sbc_cd = {
97 	NULL, "sbc", DV_DULL
98 };
99 
100 static	int	sbc_wait_busy __P((struct ncr5380_softc *));
101 static	int	sbc_ready __P((struct ncr5380_softc *));
102 static	int	sbc_wait_dreq __P((struct ncr5380_softc *));
103 
104 static void
105 sbc_minphys(struct buf *bp)
106 {
107 	if (bp->b_bcount > MAX_DMA_LEN)
108 		bp->b_bcount = MAX_DMA_LEN;
109 	return (minphys(bp));
110 }
111 
112 
113 /***
114  * General support for Mac-specific SCSI logic.
115  ***/
116 
117 /* These are used in the following inline functions. */
118 int sbc_wait_busy_timo = 1000 * 5000;	/* X2 = 10 S. */
119 int sbc_ready_timo = 1000 * 5000;	/* X2 = 10 S. */
120 int sbc_wait_dreq_timo = 1000 * 5000;	/* X2 = 10 S. */
121 
122 /* Return zero on success. */
123 static __inline__ int
124 sbc_wait_busy(sc)
125 	struct ncr5380_softc *sc;
126 {
127 	int timo = sbc_wait_busy_timo;
128 	for (;;) {
129 		if (SCI_BUSY(sc)) {
130 			timo = 0;	/* return 0 */
131 			break;
132 		}
133 		if (--timo < 0)
134 			break;	/* return -1 */
135 		delay(2);
136 	}
137 	return (timo);
138 }
139 
140 static __inline__ int
141 sbc_ready(sc)
142 	struct ncr5380_softc *sc;
143 {
144 	int timo = sbc_ready_timo;
145 
146 	for (;;) {
147 		if ((*sc->sci_csr & (SCI_CSR_DREQ|SCI_CSR_PHASE_MATCH))
148 		    == (SCI_CSR_DREQ|SCI_CSR_PHASE_MATCH)) {
149 			timo = 0;
150 			break;
151 		}
152 		if (((*sc->sci_csr & SCI_CSR_PHASE_MATCH) == 0)
153 		    || (SCI_BUSY(sc) == 0)) {
154 			timo = -1;
155 			break;
156 		}
157 		if (--timo < 0)
158 			break;	/* return -1 */
159 		delay(2);
160 	}
161 	return (timo);
162 }
163 
164 static __inline__ int
165 sbc_wait_dreq(sc)
166 	struct ncr5380_softc *sc;
167 {
168 	int timo = sbc_wait_dreq_timo;
169 
170 	for (;;) {
171 		if ((*sc->sci_csr & (SCI_CSR_DREQ|SCI_CSR_PHASE_MATCH))
172 		    == (SCI_CSR_DREQ|SCI_CSR_PHASE_MATCH)) {
173 			timo = 0;
174 			break;
175 		}
176 		if (--timo < 0)
177 			break;	/* return -1 */
178 		delay(2);
179 	}
180 	return (timo);
181 }
182 
183 void
184 sbc_irq_intr(p)
185 	void *p;
186 {
187 	struct ncr5380_softc *ncr_sc = p;
188 	int claimed = 0;
189 
190 	/* How we ever arrive here without IRQ set is a mystery... */
191 	if (*ncr_sc->sci_csr & SCI_CSR_INT) {
192 #ifdef SBC_DEBUG
193 		if (sbc_debug & SBC_DB_INTR)
194 			decode_5380_intr(ncr_sc);
195 #endif
196 		claimed = ncr5380_intr(ncr_sc);
197 		if (!claimed) {
198 			if (((*ncr_sc->sci_csr & ~SCI_CSR_PHASE_MATCH) == SCI_CSR_INT)
199 			    && ((*ncr_sc->sci_bus_csr & ~SCI_BUS_RST) == 0))
200 				SCI_CLR_INTR(ncr_sc);	/* RST interrupt */
201 #ifdef SBC_DEBUG
202 			else {
203 				printf("%s: spurious intr\n",
204 				    ncr_sc->sc_dev.dv_xname);
205 				SBC_BREAK;
206 			}
207 #endif
208 		}
209 	}
210 }
211 
212 #ifdef SBC_DEBUG
213 void
214 decode_5380_intr(ncr_sc)
215 	struct ncr5380_softc *ncr_sc;
216 {
217 	u_int8_t csr = *ncr_sc->sci_csr;
218 	u_int8_t bus_csr = *ncr_sc->sci_bus_csr;
219 
220 	if (((csr & ~(SCI_CSR_PHASE_MATCH | SCI_CSR_ATN)) == SCI_CSR_INT) &&
221 	    ((bus_csr & ~(SCI_BUS_MSG | SCI_BUS_CD | SCI_BUS_IO | SCI_BUS_DBP)) == SCI_BUS_SEL)) {
222 		if (csr & SCI_BUS_IO)
223 			printf("%s: reselect\n", ncr_sc->sc_dev.dv_xname);
224 		else
225 			printf("%s: select\n", ncr_sc->sc_dev.dv_xname);
226 	} else if (((csr & ~SCI_CSR_ACK) == (SCI_CSR_DONE | SCI_CSR_INT)) &&
227 	    ((bus_csr & (SCI_BUS_RST | SCI_BUS_BSY | SCI_BUS_SEL)) == SCI_BUS_BSY))
228 		printf("%s: dma eop\n", ncr_sc->sc_dev.dv_xname);
229 	else if (((csr & ~SCI_CSR_PHASE_MATCH) == SCI_CSR_INT) &&
230 	    ((bus_csr & ~SCI_BUS_RST) == 0))
231 		printf("%s: bus reset\n", ncr_sc->sc_dev.dv_xname);
232 	else if (((csr & ~(SCI_CSR_DREQ | SCI_CSR_ATN | SCI_CSR_ACK)) == (SCI_CSR_PERR | SCI_CSR_INT | SCI_CSR_PHASE_MATCH)) &&
233 	    ((bus_csr & (SCI_BUS_RST | SCI_BUS_BSY | SCI_BUS_SEL)) == SCI_BUS_BSY))
234 		printf("%s: parity error\n", ncr_sc->sc_dev.dv_xname);
235 	else if (((csr & ~SCI_CSR_ATN) == SCI_CSR_INT) &&
236 	    ((bus_csr & (SCI_BUS_RST | SCI_BUS_BSY | SCI_BUS_REQ | SCI_BUS_SEL)) == (SCI_BUS_BSY | SCI_BUS_REQ)))
237 		printf("%s: phase mismatch\n", ncr_sc->sc_dev.dv_xname);
238 	else if (((csr & ~SCI_CSR_PHASE_MATCH) == (SCI_CSR_INT | SCI_CSR_DISC)) &&
239 	    (bus_csr == 0))
240 		printf("%s: disconnect\n", ncr_sc->sc_dev.dv_xname);
241 	else
242 		printf("%s: unknown intr: csr=%x, bus_csr=%x\n",
243 		    ncr_sc->sc_dev.dv_xname, csr, bus_csr);
244 }
245 #endif
246 
247 
248 /***
249  * The following code implements polled PDMA.
250  ***/
251 
252 int
253 sbc_pdma_in(ncr_sc, phase, datalen, data)
254 	struct ncr5380_softc *ncr_sc;
255 	int phase;
256 	int datalen;
257 	u_char *data;
258 {
259 	struct sbc_softc *sc = (struct sbc_softc *)ncr_sc;
260 	volatile u_int32_t *long_data = (u_int32_t *)sc->sc_drq_addr;
261 	volatile u_int8_t *byte_data = (u_int8_t *)sc->sc_nodrq_addr;
262 	int resid, s;
263 
264 	if (datalen < ncr_sc->sc_min_dma_len ||
265 	    (sc->sc_options & SBC_PDMA) == 0)
266 		return ncr5380_pio_in(ncr_sc, phase, datalen, data);
267 
268 	s = splbio();
269 	if (sbc_wait_busy(ncr_sc)) {
270 		splx(s);
271 		return 0;
272 	}
273 
274 	*ncr_sc->sci_mode |= SCI_MODE_DMA;
275 	*ncr_sc->sci_irecv = 0;
276 
277 #define R4	*((u_int32_t *)data)++ = *long_data
278 #define R1	*((u_int8_t *)data)++ = *byte_data
279 	for (resid = datalen; resid >= 128; resid -= 128) {
280 		if (sbc_ready(ncr_sc))
281 			goto interrupt;
282 		R4; R4; R4; R4; R4; R4; R4; R4;
283 		R4; R4; R4; R4; R4; R4; R4; R4;
284 		R4; R4; R4; R4; R4; R4; R4; R4;
285 		R4; R4; R4; R4; R4; R4; R4; R4;		/* 128 */
286 	}
287 	while (resid) {
288 		if (sbc_ready(ncr_sc))
289 			goto interrupt;
290 		R1;
291 		resid--;
292 	}
293 #undef R4
294 #undef R1
295 
296 interrupt:
297 	SCI_CLR_INTR(ncr_sc);
298 	*ncr_sc->sci_mode &= ~SCI_MODE_DMA;
299 	*ncr_sc->sci_icmd = 0;
300 	splx(s);
301 	return (datalen - resid);
302 }
303 
304 int
305 sbc_pdma_out(ncr_sc, phase, datalen, data)
306 	struct ncr5380_softc *ncr_sc;
307 	int phase;
308 	int datalen;
309 	u_char *data;
310 {
311 	struct sbc_softc *sc = (struct sbc_softc *)ncr_sc;
312 	volatile u_int32_t *long_data = (u_int32_t *)sc->sc_drq_addr;
313 	volatile u_int8_t *byte_data = (u_int8_t *)sc->sc_nodrq_addr;
314 	int resid, s;
315 	u_int8_t icmd;
316 
317 	if (datalen < ncr_sc->sc_min_dma_len ||
318 	    (sc->sc_options & SBC_PDMA) == 0)
319 		return ncr5380_pio_out(ncr_sc, phase, datalen, data);
320 
321 	s = splbio();
322 	if (sbc_wait_busy(ncr_sc)) {
323 		splx(s);
324 		return 0;
325 	}
326 
327 	icmd = *(ncr_sc->sci_icmd) & SCI_ICMD_RMASK;
328 	*ncr_sc->sci_icmd = icmd | SCI_ICMD_DATA;
329 	*ncr_sc->sci_mode |= SCI_MODE_DMA;
330 	*ncr_sc->sci_dma_send = 0;
331 
332 #define W1	*byte_data = *((u_int8_t *)data)++
333 #define W4	*long_data = *((u_int32_t *)data)++
334 	for (resid = datalen; resid >= 64; resid -= 64) {
335 		if (sbc_ready(ncr_sc))
336 			goto interrupt;
337 		W1;
338 		if (sbc_ready(ncr_sc))
339 			goto interrupt;
340 		W1;
341 		if (sbc_ready(ncr_sc))
342 			goto interrupt;
343 		W1;
344 		if (sbc_ready(ncr_sc))
345 			goto interrupt;
346 		W1;
347 		if (sbc_ready(ncr_sc))
348 			goto interrupt;
349 		W4; W4; W4; W4;
350 		W4; W4; W4; W4;
351 		W4; W4; W4; W4;
352 		W4; W4; W4;
353 	}
354 	while (resid) {
355 		if (sbc_ready(ncr_sc))
356 			goto interrupt;
357 		W1;
358 		resid--;
359 	}
360 #undef  W1
361 #undef  W4
362 	if (sbc_wait_dreq(ncr_sc))
363 		printf("%s: timeout waiting for DREQ.\n",
364 		    ncr_sc->sc_dev.dv_xname);
365 
366 	*byte_data = 0;
367 	goto done;
368 
369 interrupt:
370 	if ((*ncr_sc->sci_csr & SCI_CSR_PHASE_MATCH) == 0) {
371 		*ncr_sc->sci_icmd = icmd & ~SCI_ICMD_DATA;
372 		--resid;
373 	}
374 
375 done:
376 	SCI_CLR_INTR(ncr_sc);
377 	*ncr_sc->sci_mode &= ~SCI_MODE_DMA;
378 	*ncr_sc->sci_icmd = icmd;
379 	splx(s);
380 	return (datalen - resid);
381 }
382 
383 
384 /***
385  * The following code implements interrupt-driven PDMA.
386  ***/
387 
388 /*
389  * This is the meat of the PDMA transfer.
390  * When we get here, we shove data as fast as the mac can take it.
391  * We depend on several things:
392  *   * All macs after the Mac Plus that have a 5380 chip should have a general
393  *     logic IC that handshakes data for blind transfers.
394  *   * If the SCSI controller finishes sending/receiving data before we do,
395  *     the same general logic IC will generate a /BERR for us in short order.
396  *   * The fault address for said /BERR minus the base address for the
397  *     transfer will be the amount of data that was actually written.
398  *
399  * We use the nofault flag and the setjmp/longjmp in locore.s so we can
400  * detect and handle the bus error for early termination of a command.
401  * This is usually caused by a disconnecting target.
402  */
403 void
404 sbc_drq_intr(p)
405 	void *p;
406 {
407 	extern int *nofault, m68k_fault_addr;
408 	struct sbc_softc *sc = (struct sbc_softc *)p;
409 	struct ncr5380_softc *ncr_sc = (struct ncr5380_softc *)p;
410 	struct sci_req *sr = ncr_sc->sc_current;
411 	struct sbc_pdma_handle *dh = sr->sr_dma_hand;
412 	label_t faultbuf;
413 	volatile u_int32_t *long_drq;
414 	u_int32_t *long_data;
415 	volatile u_int8_t *drq;
416 	u_int8_t *data;
417 	int count, dcount, resid;
418 	u_int8_t tmp;
419 
420 	/* Work around lame gcc initialization bug */
421 	(void)&drq;
422 
423 	/*
424 	 * If we're not ready to xfer data, or have no more, just return.
425 	 */
426 	if ((*ncr_sc->sci_csr & SCI_CSR_DREQ) == 0 || dh->dh_len == 0)
427 		return;
428 
429 #ifdef SBC_DEBUG
430 	if (sbc_debug & SBC_DB_INTR)
431 		printf("%s: drq intr, dh_len=0x%x, dh_flags=0x%x\n",
432 		    ncr_sc->sc_dev.dv_xname, dh->dh_len, dh->dh_flags);
433 #endif
434 
435 	/*
436 	 * Setup for a possible bus error caused by SCSI controller
437 	 * switching out of DATA-IN/OUT before we're done with the
438 	 * current transfer.
439 	 */
440 	nofault = (int *)&faultbuf;
441 
442 	if (setjmp((label_t *)nofault)) {
443 		nofault = (int *)0;
444 		if ((dh->dh_flags & SBC_DH_DONE) == 0) {
445 			count = ((  (u_long)m68k_fault_addr
446 				  - (u_long)sc->sc_drq_addr));
447 
448 			if ((count < 0) || (count > dh->dh_len)) {
449 				printf("%s: complete=0x%x (pending 0x%x)\n",
450 				    ncr_sc->sc_dev.dv_xname, count, dh->dh_len);
451 				panic("something is wrong");
452 			}
453 
454 			dh->dh_addr += count;
455 			dh->dh_len -= count;
456 		} else
457 			count = 0;
458 
459 #ifdef SBC_DEBUG
460 		if (sbc_debug & SBC_DB_INTR)
461 			printf("%s: drq /berr, complete=0x%x (pending 0x%x)\n",
462 			   ncr_sc->sc_dev.dv_xname, count, dh->dh_len);
463 #endif
464 		m68k_fault_addr = 0;
465 
466 		return;
467 	}
468 
469 	if (dh->dh_flags & SBC_DH_OUT) { /* Data Out */
470 		dcount = 0;
471 
472 		/*
473 		 * Get the source address aligned.
474 		 */
475 		resid =
476 		    count = min(dh->dh_len, 4 - (((int)dh->dh_addr) & 0x3));
477 		if (count && count < 4) {
478 			drq = (volatile u_int8_t *)sc->sc_drq_addr;
479 			data = (u_int8_t *)dh->dh_addr;
480 
481 #define W1		*drq++ = *data++
482 			while (count) {
483 				W1; count--;
484 			}
485 #undef W1
486 			dh->dh_addr += resid;
487 			dh->dh_len -= resid;
488 		}
489 
490 		/*
491 		 * Start the transfer.
492 		 */
493 		while (dh->dh_len) {
494 			dcount = count = min(dh->dh_len, MAX_DMA_LEN);
495 			long_drq = (volatile u_int32_t *)sc->sc_drq_addr;
496 			long_data = (u_int32_t *)dh->dh_addr;
497 
498 #define W4		*long_drq++ = *long_data++
499 			while (count >= 64) {
500 				W4; W4; W4; W4; W4; W4; W4; W4;
501 				W4; W4; W4; W4; W4; W4; W4; W4; /*  64 */
502 				count -= 64;
503 			}
504 			while (count >= 4) {
505 				W4; count -= 4;
506 			}
507 #undef W4
508 			data = (u_int8_t *)long_data;
509 			drq = (u_int8_t *)long_drq;
510 
511 #define W1		*drq++ = *data++
512 			while (count) {
513 				W1; count--;
514 			}
515 #undef W1
516 			dh->dh_len -= dcount;
517 			dh->dh_addr += dcount;
518 		}
519 		dh->dh_flags |= SBC_DH_DONE;
520 
521 		/*
522 		 * XXX -- Read a byte from the SBC to trigger a /BERR.
523 		 * This seems to be necessary for us to notice that
524 		 * the target has disconnected.  Ick.  06 jun 1996 (sr)
525 		 */
526 		if (dcount >= MAX_DMA_LEN)
527 			drq = (volatile u_int8_t *)sc->sc_drq_addr;
528 		tmp = *drq;
529 	} else {	/* Data In */
530 		/*
531 		 * Get the dest address aligned.
532 		 */
533 		resid =
534 		    count = min(dh->dh_len, 4 - (((int)dh->dh_addr) & 0x3));
535 		if (count && count < 4) {
536 			data = (u_int8_t *)dh->dh_addr;
537 			drq = (volatile u_int8_t *)sc->sc_drq_addr;
538 
539 #define R1		*data++ = *drq++
540 			while (count) {
541 				R1; count--;
542 			}
543 #undef R1
544 			dh->dh_addr += resid;
545 			dh->dh_len -= resid;
546 		}
547 
548 		/*
549 		 * Start the transfer.
550 		 */
551 		while (dh->dh_len) {
552 			dcount = count = min(dh->dh_len, MAX_DMA_LEN);
553 			long_data = (u_int32_t *)dh->dh_addr;
554 			long_drq = (volatile u_int32_t *)sc->sc_drq_addr;
555 
556 #define R4		*long_data++ = *long_drq++
557 			while (count >= 64) {
558 				R4; R4; R4; R4; R4; R4; R4; R4;
559 				R4; R4; R4; R4; R4; R4; R4; R4;	/* 64 */
560 				count -= 64;
561 			}
562 			while (count >= 4) {
563 				R4; count -= 4;
564 			}
565 #undef R4
566 			data = (u_int8_t *)long_data;
567 			drq = (volatile u_int8_t *)long_drq;
568 
569 #define R1		*data++ = *drq++
570 			while (count) {
571 				R1; count--;
572 			}
573 #undef R1
574 			dh->dh_len -= dcount;
575 			dh->dh_addr += dcount;
576 		}
577 		dh->dh_flags |= SBC_DH_DONE;
578 	}
579 
580 	/*
581 	 * OK.  No bus error occurred above.  Clear the nofault flag
582 	 * so we no longer short-circuit bus errors.
583 	 */
584 	nofault = (int *)0;
585 
586 #ifdef SBC_DEBUG
587 	if (sbc_debug & (SBC_DB_REG | SBC_DB_INTR))
588 		printf("%s: drq intr complete: csr=0x%x, bus_csr=0x%x\n",
589 		    ncr_sc->sc_dev.dv_xname, *ncr_sc->sci_csr,
590 		    *ncr_sc->sci_bus_csr);
591 #endif
592 }
593 
594 void
595 sbc_dma_alloc(ncr_sc)
596 	struct ncr5380_softc *ncr_sc;
597 {
598 	struct sbc_softc *sc = (struct sbc_softc *)ncr_sc;
599 	struct sci_req *sr = ncr_sc->sc_current;
600 	struct scsi_xfer *xs = sr->sr_xs;
601 	struct sbc_pdma_handle *dh;
602 	int		i, xlen;
603 
604 #ifdef DIAGNOSTIC
605 	if (sr->sr_dma_hand != NULL)
606 		panic("sbc_dma_alloc: already have PDMA handle");
607 #endif
608 
609 	/* Polled transfers shouldn't allocate a PDMA handle. */
610 	if (sr->sr_flags & SR_IMMED)
611 		return;
612 
613 	xlen = ncr_sc->sc_datalen;
614 
615 	/* Make sure our caller checked sc_min_dma_len. */
616 	if (xlen < MIN_DMA_LEN)
617 		panic("sbc_dma_alloc: len=0x%x\n", xlen);
618 
619 	/*
620 	 * Find free PDMA handle.  Guaranteed to find one since we
621 	 * have as many PDMA handles as the driver has processes.
622 	 * (instances?)
623 	 */
624 	 for (i = 0; i < SCI_OPENINGS; i++) {
625 		if ((sc->sc_pdma[i].dh_flags & SBC_DH_BUSY) == 0)
626 			goto found;
627 	}
628 	panic("sbc: no free PDMA handles");
629 found:
630 	dh = &sc->sc_pdma[i];
631 	dh->dh_flags = SBC_DH_BUSY;
632 	dh->dh_addr = ncr_sc->sc_dataptr;
633 	dh->dh_len = xlen;
634 
635 	/* Copy the 'write' flag for convenience. */
636 	if (xs->flags & SCSI_DATA_OUT)
637 		dh->dh_flags |= SBC_DH_OUT;
638 
639 	sr->sr_dma_hand = dh;
640 }
641 
642 void
643 sbc_dma_free(ncr_sc)
644 	struct ncr5380_softc *ncr_sc;
645 {
646 	struct sci_req *sr = ncr_sc->sc_current;
647 	struct sbc_pdma_handle *dh = sr->sr_dma_hand;
648 
649 #ifdef DIAGNOSTIC
650 	if (sr->sr_dma_hand == NULL)
651 		panic("sbc_dma_free: no DMA handle");
652 #endif
653 
654 	if (ncr_sc->sc_state & NCR_DOINGDMA)
655 		panic("sbc_dma_free: free while in progress");
656 
657 	if (dh->dh_flags & SBC_DH_BUSY) {
658 		dh->dh_flags = 0;
659 		dh->dh_addr = NULL;
660 		dh->dh_len = 0;
661 	}
662 	sr->sr_dma_hand = NULL;
663 }
664 
665 void
666 sbc_dma_poll(ncr_sc)
667 	struct ncr5380_softc *ncr_sc;
668 {
669 	struct sci_req *sr = ncr_sc->sc_current;
670 
671 	/*
672 	 * We shouldn't arrive here; if SR_IMMED is set, then
673 	 * dma_alloc() should have refused to allocate a handle
674 	 * for the transfer.  This forces the polled PDMA code
675 	 * to handle the request...
676 	 */
677 #ifdef SBC_DEBUG
678 	if (sbc_debug & SBC_DB_DMA)
679 		printf("%s: lost DRQ interrupt?\n", ncr_sc->sc_dev.dv_xname);
680 #endif
681 	sr->sr_flags |= SR_OVERDUE;
682 }
683 
684 void
685 sbc_dma_setup(ncr_sc)
686 	struct ncr5380_softc *ncr_sc;
687 {
688 	/* Not needed; we don't have real DMA */
689 }
690 
691 void
692 sbc_dma_start(ncr_sc)
693 	struct ncr5380_softc *ncr_sc;
694 {
695 	struct sbc_softc *sc = (struct sbc_softc *)ncr_sc;
696 	struct sci_req *sr = ncr_sc->sc_current;
697 	struct sbc_pdma_handle *dh = sr->sr_dma_hand;
698 
699 	/*
700 	 * Match bus phase, clear pending interrupts, set DMA mode, and
701 	 * assert data bus (for writing only), then start the transfer.
702 	 */
703 	if (dh->dh_flags & SBC_DH_OUT) {
704 		*ncr_sc->sci_tcmd = PHASE_DATA_OUT;
705 		SCI_CLR_INTR(ncr_sc);
706 		if (sc->sc_clrintr)
707 			(*sc->sc_clrintr)(ncr_sc);
708 		*ncr_sc->sci_mode |= SCI_MODE_DMA;
709 		*ncr_sc->sci_icmd = SCI_ICMD_DATA;
710 		*ncr_sc->sci_dma_send = 0;
711 	} else {
712 		*ncr_sc->sci_tcmd = PHASE_DATA_IN;
713 		SCI_CLR_INTR(ncr_sc);
714 		if (sc->sc_clrintr)
715 			(*sc->sc_clrintr)(ncr_sc);
716 		*ncr_sc->sci_mode |= SCI_MODE_DMA;
717 		*ncr_sc->sci_icmd = 0;
718 		*ncr_sc->sci_irecv = 0;
719 	}
720 	ncr_sc->sc_state |= NCR_DOINGDMA;
721 
722 #ifdef SBC_DEBUG
723 	if (sbc_debug & SBC_DB_DMA)
724 		printf("%s: PDMA started, va=%p, len=0x%x\n",
725 		    ncr_sc->sc_dev.dv_xname, dh->dh_addr, dh->dh_len);
726 #endif
727 }
728 
729 void
730 sbc_dma_eop(ncr_sc)
731 	struct ncr5380_softc *ncr_sc;
732 {
733 	/* Not used; the EOP pin is wired high (GMFH, pp. 389-390) */
734 }
735 
736 void
737 sbc_dma_stop(ncr_sc)
738 	struct ncr5380_softc *ncr_sc;
739 {
740 	struct sbc_softc *sc = (struct sbc_softc *)ncr_sc;
741 	struct sci_req *sr = ncr_sc->sc_current;
742 	struct sbc_pdma_handle *dh = sr->sr_dma_hand;
743 	int ntrans;
744 
745 	if ((ncr_sc->sc_state & NCR_DOINGDMA) == 0) {
746 #ifdef SBC_DEBUG
747 		if (sbc_debug & SBC_DB_DMA)
748 			printf("%s: dma_stop: DMA not running\n",
749 			    ncr_sc->sc_dev.dv_xname);
750 #endif
751 		return;
752 	}
753 	ncr_sc->sc_state &= ~NCR_DOINGDMA;
754 
755 	if ((ncr_sc->sc_state & NCR_ABORTING) == 0) {
756 		ntrans = ncr_sc->sc_datalen - dh->dh_len;
757 
758 #ifdef SBC_DEBUG
759 		if (sbc_debug & SBC_DB_DMA)
760 			printf("%s: dma_stop: ntrans=0x%x\n",
761 			    ncr_sc->sc_dev.dv_xname, ntrans);
762 #endif
763 
764 		if (ntrans > ncr_sc->sc_datalen)
765 			panic("sbc_dma_stop: excess transfer\n");
766 
767 		/* Adjust data pointer */
768 		ncr_sc->sc_dataptr += ntrans;
769 		ncr_sc->sc_datalen -= ntrans;
770 
771 		/* Clear any pending interrupts. */
772 		SCI_CLR_INTR(ncr_sc);
773 		if (sc->sc_clrintr)
774 			(*sc->sc_clrintr)(ncr_sc);
775 	}
776 
777 	/* Put SBIC back into PIO mode. */
778 	*ncr_sc->sci_mode &= ~SCI_MODE_DMA;
779 	*ncr_sc->sci_icmd = 0;
780 
781 #ifdef SBC_DEBUG
782 	if (sbc_debug & SBC_DB_REG)
783 		printf("%s: dma_stop: csr=0x%x, bus_csr=0x%x\n",
784 		    ncr_sc->sc_dev.dv_xname, *ncr_sc->sci_csr,
785 		    *ncr_sc->sci_bus_csr);
786 #endif
787 }
788