xref: /netbsd-src/sys/arch/next68k/dev/nextdma.c (revision 95d875fb90b1458e4f1de6950286ddcd6644bc61)
1 /*	$NetBSD: nextdma.c,v 1.20 1999/08/29 05:56:26 dbj Exp $	*/
2 /*
3  * Copyright (c) 1998 Darrin B. Jewell
4  * 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 Darrin B. Jewell
17  * 4. The name of the author may not be used to endorse or promote products
18  *    derived from this software without specific prior written permission
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
21  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/mbuf.h>
35 #include <sys/syslog.h>
36 #include <sys/socket.h>
37 #include <sys/device.h>
38 #include <sys/malloc.h>
39 #include <sys/ioctl.h>
40 #include <sys/errno.h>
41 
42 #include <machine/autoconf.h>
43 #include <machine/cpu.h>
44 #include <machine/intr.h>
45 
46 #include <m68k/cacheops.h>
47 
48 #include <next68k/next68k/isr.h>
49 
50 #define _NEXT68K_BUS_DMA_PRIVATE
51 #include <machine/bus.h>
52 
53 #include "nextdmareg.h"
54 #include "nextdmavar.h"
55 
56 #if 1
57 #define ND_DEBUG
58 #endif
59 
60 #if defined(ND_DEBUG)
61 int nextdma_debug = 0;
62 #define DPRINTF(x) if (nextdma_debug) printf x;
63 #else
64 #define DPRINTF(x)
65 #endif
66 
67 void next_dmamap_sync __P((bus_dma_tag_t, bus_dmamap_t, bus_addr_t,
68                        bus_size_t, int));
69 int next_dma_continue __P((struct nextdma_config *));
70 void next_dma_rotate __P((struct nextdma_config *));
71 
72 void next_dma_setup_cont_regs __P((struct nextdma_config *));
73 void next_dma_setup_curr_regs __P((struct nextdma_config *));
74 void next_dma_finish_xfer __P((struct nextdma_config *));
75 
76 void
77 nextdma_config(nd)
78 	struct nextdma_config *nd;
79 {
80 	/* Initialize the dma_tag. As a hack, we currently
81 	 * put the dma tag in the structure itself.  It shouldn't be there.
82 	 */
83 
84 	{
85 		bus_dma_tag_t t;
86 		t = &nd->_nd_dmat;
87 		t->_cookie = nd;
88 		t->_dmamap_create = _bus_dmamap_create;
89 		t->_dmamap_destroy = _bus_dmamap_destroy;
90 		t->_dmamap_load = _bus_dmamap_load_direct;
91 		t->_dmamap_load_mbuf = _bus_dmamap_load_mbuf_direct;
92 		t->_dmamap_load_uio = _bus_dmamap_load_uio_direct;
93 		t->_dmamap_load_raw = _bus_dmamap_load_raw_direct;
94 		t->_dmamap_unload = _bus_dmamap_unload;
95 		t->_dmamap_sync = _bus_dmamap_sync;
96 
97 		t->_dmamem_alloc = _bus_dmamem_alloc;
98 		t->_dmamem_free = _bus_dmamem_free;
99 		t->_dmamem_map = _bus_dmamem_map;
100 		t->_dmamem_unmap = _bus_dmamem_unmap;
101 		t->_dmamem_mmap = _bus_dmamem_mmap;
102 
103 		nd->nd_dmat = t;
104 	}
105 
106 	nextdma_init(nd);
107 
108 	isrlink_autovec(nextdma_intr, nd, NEXT_I_IPL(nd->nd_intr), 10);
109 	INTR_ENABLE(nd->nd_intr);
110 }
111 
112 void
113 nextdma_init(nd)
114 	struct nextdma_config *nd;
115 {
116   DPRINTF(("DMA init ipl (%ld) intr(0x%b)\n",
117 			NEXT_I_IPL(nd->nd_intr), NEXT_I_BIT(nd->nd_intr),NEXT_INTR_BITS));
118 
119 	nd->_nd_map = NULL;
120 	nd->_nd_idx = 0;
121 	nd->_nd_map_cont = NULL;
122 	nd->_nd_idx_cont = 0;
123 
124 	bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_CSR, 0);
125 	bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_CSR,
126 			DMACSR_RESET | DMACSR_INITBUF);
127 
128 	next_dma_setup_curr_regs(nd);
129 	next_dma_setup_cont_regs(nd);
130 
131 #if defined(DIAGNOSTIC)
132 	{
133 		u_long state;
134 		state = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_CSR);
135 
136 #if 1
137 	/* mourning (a 25Mhz 68040 mono slab) appears to set BUSEXC
138 	 * milo (a 25Mhz 68040 mono cube) didn't have this problem
139 	 * Darrin B. Jewell <jewell@mit.edu>  Mon May 25 07:53:05 1998
140 	 */
141     state &= (DMACSR_COMPLETE | DMACSR_SUPDATE | DMACSR_ENABLE);
142 #else
143     state &= (DMACSR_BUSEXC | DMACSR_COMPLETE |
144               DMACSR_SUPDATE | DMACSR_ENABLE);
145 #endif
146 		if (state) {
147 			next_dma_print(nd);
148 			panic("DMA did not reset");
149 		}
150 	}
151 #endif
152 }
153 
154 
155 void
156 nextdma_reset(nd)
157 	struct nextdma_config *nd;
158 {
159 	int s;
160 	s = spldma();
161 
162 	DPRINTF(("DMA reset\n"));
163 
164 #if (defined(ND_DEBUG))
165 	if (nextdma_debug) next_dma_print(nd);
166 #endif
167 
168 	/* @@@ clean up dma maps */
169 
170 	nextdma_init(nd);
171 	splx(s);
172 }
173 
174 /****************************************************************/
175 
176 
177 /* Call the completed and continue callbacks to try to fill
178  * in the dma continue buffers.
179  */
180 void
181 next_dma_rotate(nd)
182 	struct nextdma_config *nd;
183 {
184 
185 	DPRINTF(("DMA next_dma_rotate()\n"));
186 
187 	/* Rotate the continue map into the current map */
188 	nd->_nd_map = nd->_nd_map_cont;
189 	nd->_nd_idx = nd->_nd_idx_cont;
190 
191 	if ((!nd->_nd_map_cont) ||
192 			((nd->_nd_map_cont) &&
193 					(++nd->_nd_idx_cont >= nd->_nd_map_cont->dm_nsegs))) {
194 		if (nd->nd_continue_cb) {
195 			nd->_nd_map_cont = (*nd->nd_continue_cb)(nd->nd_cb_arg);
196 		} else {
197 			nd->_nd_map_cont = 0;
198 		}
199 		nd->_nd_idx_cont = 0;
200 	}
201 
202 #ifdef DIAGNOSTIC
203 	if (nd->_nd_map) {
204 		nd->_nd_map->dm_segs[nd->_nd_idx].ds_xfer_len = 0x1234beef;
205 	}
206 #endif
207 
208 #ifdef DIAGNOSTIC
209 	if (nd->_nd_map_cont) {
210 		if (!DMA_BEGINALIGNED(nd->_nd_map_cont->dm_segs[nd->_nd_idx_cont].ds_addr)) {
211 			next_dma_print(nd);
212 			panic("DMA request unaligned at start\n");
213 		}
214 		if (!DMA_ENDALIGNED(nd->_nd_map_cont->dm_segs[nd->_nd_idx_cont].ds_addr +
215 				nd->_nd_map_cont->dm_segs[nd->_nd_idx_cont].ds_len)) {
216 			next_dma_print(nd);
217 			panic("DMA request unaligned at end\n");
218 		}
219 	}
220 #endif
221 
222 }
223 
224 void
225 next_dma_setup_cont_regs(nd)
226 	struct nextdma_config *nd;
227 {
228 	bus_addr_t dd_start;
229 	bus_addr_t dd_stop;
230 	bus_addr_t dd_saved_start;
231 	bus_addr_t dd_saved_stop;
232 
233 	DPRINTF(("DMA next_dma_setup_regs()\n"));
234 
235 	if (nd->_nd_map_cont) {
236 		dd_start = nd->_nd_map_cont->dm_segs[nd->_nd_idx_cont].ds_addr;
237 		dd_stop  = (nd->_nd_map_cont->dm_segs[nd->_nd_idx_cont].ds_addr +
238 				nd->_nd_map_cont->dm_segs[nd->_nd_idx_cont].ds_len);
239 
240 		if (nd->nd_intr == NEXT_I_ENETX_DMA) {
241 			dd_stop |= 0x80000000;		/* Ethernet transmit needs secret magic */
242 		}
243 	} else {
244 		dd_start = 0xdeadbeef;
245 		dd_stop = 0xdeadbeef;
246 	}
247 
248 	dd_saved_start = dd_start;
249 	dd_saved_stop  = dd_stop;
250 
251 	bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_START, dd_start);
252 	bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_STOP, dd_stop);
253 	bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_START, dd_saved_start);
254 	bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_STOP, dd_saved_stop);
255 
256 #ifdef DIAGNOSTIC
257 	if ((bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_START) != dd_start) ||
258 			(bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_STOP) != dd_stop) ||
259 			(bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_START) != dd_saved_start) ||
260 			(bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_STOP) != dd_saved_stop)) {
261 		next_dma_print(nd);
262 		panic("DMA failure writing to continue regs");
263 	}
264 #endif
265 }
266 
267 void
268 next_dma_setup_curr_regs(nd)
269 	struct nextdma_config *nd;
270 {
271 	bus_addr_t dd_next;
272 	bus_addr_t dd_limit;
273 	bus_addr_t dd_saved_next;
274 	bus_addr_t dd_saved_limit;
275 
276 	DPRINTF(("DMA next_dma_setup_curr_regs()\n"));
277 
278 
279 	if (nd->_nd_map) {
280 		dd_next = nd->_nd_map->dm_segs[nd->_nd_idx].ds_addr;
281 		dd_limit = (nd->_nd_map->dm_segs[nd->_nd_idx].ds_addr +
282 				nd->_nd_map->dm_segs[nd->_nd_idx].ds_len);
283 		if (nd->nd_intr == NEXT_I_ENETX_DMA) {
284 			dd_limit |= 0x80000000; /* Ethernet transmit needs secret magic */
285 		}
286 	} else {
287 		dd_next = 0xdeadbeef;
288 		dd_limit = 0xdeadbeef;
289 	}
290 
291 	dd_saved_next = dd_next;
292 	dd_saved_limit = dd_limit;
293 
294 	if (nd->nd_intr == NEXT_I_ENETX_DMA) {
295 		bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_NEXT_INITBUF, dd_next);
296 	} else {
297 		bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_NEXT, dd_next);
298 	}
299 	bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_LIMIT, dd_limit);
300 	bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_NEXT, dd_saved_next);
301 	bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_LIMIT, dd_saved_limit);
302 
303 #ifdef DIAGNOSTIC
304 	if ((bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_NEXT_INITBUF) != dd_next) ||
305 			(bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_NEXT) != dd_next) ||
306 			(bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_LIMIT) != dd_limit) ||
307 			(bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_NEXT) != dd_saved_next) ||
308 			(bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_LIMIT) != dd_saved_limit)) {
309 		next_dma_print(nd);
310 		panic("DMA failure writing to current regs");
311 	}
312 #endif
313 }
314 
315 
316 /* This routine is used for debugging */
317 
318 void
319 next_dma_print(nd)
320 	struct nextdma_config *nd;
321 {
322 	u_long dd_csr;
323 	u_long dd_next;
324 	u_long dd_next_initbuf;
325 	u_long dd_limit;
326 	u_long dd_start;
327 	u_long dd_stop;
328 	u_long dd_saved_next;
329 	u_long dd_saved_limit;
330 	u_long dd_saved_start;
331 	u_long dd_saved_stop;
332 
333   /* Read all of the registers before we print anything out,
334 	 * in case something changes
335 	 */
336 	dd_csr          = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_CSR);
337 	dd_next         = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_NEXT);
338 	dd_next_initbuf = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_NEXT_INITBUF);
339 	dd_limit        = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_LIMIT);
340 	dd_start        = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_START);
341 	dd_stop         = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_STOP);
342 	dd_saved_next   = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_NEXT);
343 	dd_saved_limit  = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_LIMIT);
344 	dd_saved_start  = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_START);
345 	dd_saved_stop   = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_STOP);
346 
347 	printf("NDMAP: *intrstat = 0x%b\n",
348 			(*(volatile u_long *)IIOV(NEXT_P_INTRSTAT)),NEXT_INTR_BITS);
349 	printf("NDMAP: *intrmask = 0x%b\n",
350 			(*(volatile u_long *)IIOV(NEXT_P_INTRMASK)),NEXT_INTR_BITS);
351 
352 	/* NDMAP is Next DMA Print (really!) */
353 
354 	if (nd->_nd_map) {
355 		printf("NDMAP: nd->_nd_map->dm_mapsize = %d\n",
356 				nd->_nd_map->dm_mapsize);
357 		printf("NDMAP: nd->_nd_map->dm_nsegs = %d\n",
358 				nd->_nd_map->dm_nsegs);
359 		printf("NDMAP: nd->_nd_map->dm_segs[%d].ds_addr = 0x%08lx\n",
360 				nd->_nd_idx,nd->_nd_map->dm_segs[nd->_nd_idx].ds_addr);
361 		printf("NDMAP: nd->_nd_map->dm_segs[%d].ds_len = %d\n",
362 				nd->_nd_idx,nd->_nd_map->dm_segs[nd->_nd_idx].ds_len);
363 		printf("NDMAP: nd->_nd_map->dm_segs[%d].ds_xfer_len = %d\n",
364 				nd->_nd_idx,nd->_nd_map->dm_segs[nd->_nd_idx].ds_xfer_len);
365 	} else {
366 		printf("NDMAP: nd->_nd_map = NULL\n");
367 	}
368 	if (nd->_nd_map_cont) {
369 		printf("NDMAP: nd->_nd_map_cont->dm_mapsize = %d\n",
370 				nd->_nd_map_cont->dm_mapsize);
371 		printf("NDMAP: nd->_nd_map_cont->dm_nsegs = %d\n",
372 				nd->_nd_map_cont->dm_nsegs);
373 		printf("NDMAP: nd->_nd_map_cont->dm_segs[%d].ds_addr = 0x%08lx\n",
374 				nd->_nd_idx_cont,nd->_nd_map_cont->dm_segs[nd->_nd_idx_cont].ds_addr);
375 		printf("NDMAP: nd->_nd_map_cont->dm_segs[%d].ds_len = %d\n",
376 				nd->_nd_idx_cont,nd->_nd_map_cont->dm_segs[nd->_nd_idx_cont].ds_len);
377 		printf("NDMAP: nd->_nd_map_cont->dm_segs[%d].ds_xfer_len = %d\n",
378 				nd->_nd_idx_cont,nd->_nd_map_cont->dm_segs[nd->_nd_idx_cont].ds_xfer_len);
379 	} else {
380 		printf("NDMAP: nd->_nd_map_cont = NULL\n");
381 	}
382 
383 	printf("NDMAP: dd->dd_csr          = 0x%b\n",   dd_csr,   DMACSR_BITS);
384 	printf("NDMAP: dd->dd_saved_next   = 0x%08x\n", dd_saved_next);
385 	printf("NDMAP: dd->dd_saved_limit  = 0x%08x\n", dd_saved_limit);
386 	printf("NDMAP: dd->dd_saved_start  = 0x%08x\n", dd_saved_start);
387 	printf("NDMAP: dd->dd_saved_stop   = 0x%08x\n", dd_saved_stop);
388 	printf("NDMAP: dd->dd_next         = 0x%08x\n", dd_next);
389 	printf("NDMAP: dd->dd_next_initbuf = 0x%08x\n", dd_next_initbuf);
390 	printf("NDMAP: dd->dd_limit        = 0x%08x\n", dd_limit);
391 	printf("NDMAP: dd->dd_start        = 0x%08x\n", dd_start);
392 	printf("NDMAP: dd->dd_stop         = 0x%08x\n", dd_stop);
393 
394 	printf("NDMAP: interrupt ipl (%ld) intr(0x%b)\n",
395 			NEXT_I_IPL(nd->nd_intr), NEXT_I_BIT(nd->nd_intr),NEXT_INTR_BITS);
396 }
397 
398 /****************************************************************/
399 void
400 next_dma_finish_xfer(nd)
401 	struct nextdma_config *nd;
402 {
403 	bus_addr_t onext;
404 	bus_addr_t olimit;
405 	bus_addr_t slimit;
406 
407 	onext = nd->_nd_map->dm_segs[nd->_nd_idx].ds_addr;
408 	olimit = onext + nd->_nd_map->dm_segs[nd->_nd_idx].ds_len;
409 
410 	if ((nd->_nd_map_cont == NULL) && (nd->_nd_idx+1 == nd->_nd_map->dm_nsegs)) {
411 		slimit = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_LIMIT);
412 	} else {
413 		slimit = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_SAVED_LIMIT);
414 	}
415 
416 	if (nd->nd_intr == NEXT_I_ENETX_DMA) {
417 		slimit &= ~0x80000000;
418 	}
419 
420 #ifdef DIAGNOSTIC
421 	if ((slimit < onext) || (slimit > olimit)) {
422 		next_dma_print(nd);
423 		panic("DMA: Unexpected registers in finish_xfer\n");
424 	}
425 #endif
426 
427 	nd->_nd_map->dm_segs[nd->_nd_idx].ds_xfer_len = slimit-onext;
428 
429 	/* If we've reached the end of the current map, then inform
430 	 * that we've completed that map.
431 	 */
432 	if (nd->_nd_map && ((nd->_nd_idx+1) == nd->_nd_map->dm_nsegs)) {
433 		if (nd->nd_completed_cb)
434 			(*nd->nd_completed_cb)(nd->_nd_map, nd->nd_cb_arg);
435 	}
436 	nd->_nd_map = 0;
437 	nd->_nd_idx = 0;
438 }
439 
440 
441 int
442 nextdma_intr(arg)
443      void *arg;
444 {
445   /* @@@ This is bogus, we can't be certain of arg's type
446 	 * unless the interrupt is for us.  For now we successfully
447 	 * cheat because DMA interrupts are the only things invoked
448 	 * at this interrupt level.
449 	 */
450   struct nextdma_config *nd = arg;
451 
452   if (!INTR_OCCURRED(nd->nd_intr)) return 0;
453   /* Handle dma interrupts */
454 
455   DPRINTF(("DMA interrupt ipl (%ld) intr(0x%b)\n",
456           NEXT_I_IPL(nd->nd_intr), NEXT_I_BIT(nd->nd_intr),NEXT_INTR_BITS));
457 
458 #ifdef DIAGNOSTIC
459 	if (!nd->_nd_map) {
460 		next_dma_print(nd);
461 		panic("DMA missing current map in interrupt!\n");
462 	}
463 #endif
464 
465   {
466     int state = bus_space_read_4(nd->nd_bst, nd->nd_bsh, DD_CSR);
467 
468 #ifdef DIAGNOSTIC
469 		if ((!(state & DMACSR_COMPLETE)) || (state & DMACSR_SUPDATE)) {
470 			next_dma_print(nd);
471 			panic("DMA Unexpected dma state in interrupt (0x%b)",state,DMACSR_BITS);
472 		}
473 #endif
474 
475 		next_dma_finish_xfer(nd);
476 
477 		/* Check to see if we are expecting dma to shut down */
478 		if ((nd->_nd_map == NULL) && (nd->_nd_map_cont == NULL)) {
479 
480 #ifdef DIAGNOSTIC
481 			if (state & DMACSR_ENABLE) {
482 				next_dma_print(nd);
483 				panic("DMA: unexpected DMA state at shutdown (0x%b)\n",
484 						state,DMACSR_BITS);
485 			}
486 #endif
487 			bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_CSR,
488 					DMACSR_CLRCOMPLETE | DMACSR_RESET);
489 
490 			DPRINTF(("DMA: a normal and expected shutdown occurred\n"));
491 			if (nd->nd_shutdown_cb) (*nd->nd_shutdown_cb)(nd->nd_cb_arg);
492 
493 			return(1);
494 		}
495 
496 		next_dma_rotate(nd);
497 		next_dma_setup_cont_regs(nd);
498 
499 		{
500 			u_long dmadir;								/* 	DMACSR_SETREAD or DMACSR_SETWRITE */
501 
502 			if (state & DMACSR_READ) {
503 				dmadir = DMACSR_SETREAD;
504 			} else {
505 				dmadir = DMACSR_SETWRITE;
506 			}
507 
508 			if (state & DMACSR_ENABLE) {
509 
510 				if ((nd->_nd_map_cont == NULL) && (nd->_nd_idx+1 == nd->_nd_map->dm_nsegs)) {
511 					bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_CSR,
512 							DMACSR_CLRCOMPLETE | dmadir);
513 				} else {
514 					bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_CSR,
515 							DMACSR_CLRCOMPLETE | dmadir | DMACSR_SETSUPDATE);
516 				}
517 
518 			} else {
519 
520 #if (defined(ND_DEBUG))
521 				if (nextdma_debug) next_dma_print(nd);
522 #endif
523 #if 0 && defined(DIAGNOSTIC)
524 				printf("DMA: Unexpected shutdown, restarting intr(0x%b)\n",
525 						NEXT_I_BIT(nd->nd_intr),NEXT_INTR_BITS);
526 #endif
527 
528 				if ((nd->_nd_map_cont == NULL) && (nd->_nd_idx+1 == nd->_nd_map->dm_nsegs)) {
529 					bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_CSR,
530 							DMACSR_CLRCOMPLETE | dmadir | DMACSR_SETENABLE);
531 				} else {
532 					bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_CSR,
533 							DMACSR_CLRCOMPLETE | dmadir | DMACSR_SETSUPDATE | DMACSR_SETENABLE);
534 				}
535 			}
536 		}
537 
538 	}
539 
540   DPRINTF(("DMA exiting interrupt ipl (%ld) intr(0x%b)\n",
541           NEXT_I_IPL(nd->nd_intr), NEXT_I_BIT(nd->nd_intr),NEXT_INTR_BITS));
542 
543   return(1);
544 }
545 
546 /*
547  * Check to see if dma has finished for a channel */
548 int
549 nextdma_finished(nd)
550 	struct nextdma_config *nd;
551 {
552 	int r;
553 	int s;
554 	s = spldma();									/* @@@ should this be splimp()? */
555 	r = (nd->_nd_map == NULL) && (nd->_nd_map_cont == NULL);
556 	splx(s);
557 	return(r);
558 }
559 
560 void
561 nextdma_start(nd, dmadir)
562 	struct nextdma_config *nd;
563 	u_long dmadir;								/* 	DMACSR_SETREAD or DMACSR_SETWRITE */
564 {
565 
566 #ifdef DIAGNOSTIC
567 	if (!nextdma_finished(nd)) {
568 		panic("DMA trying to start before previous finished on intr(0x%b)\n",
569 				NEXT_I_BIT(nd->nd_intr),NEXT_INTR_BITS);
570 	}
571 #endif
572 
573   DPRINTF(("DMA start (%ld) intr(0x%b)\n",
574           NEXT_I_IPL(nd->nd_intr), NEXT_I_BIT(nd->nd_intr),NEXT_INTR_BITS));
575 
576 #ifdef DIAGNOSTIC
577 	if (nd->_nd_map) {
578 		next_dma_print(nd);
579 		panic("DMA: nextdma_start() with non null map\n");
580 	}
581 	if (nd->_nd_map_cont) {
582 		next_dma_print(nd);
583 		panic("DMA: nextdma_start() with non null continue map\n");
584 	}
585 #endif
586 
587 #ifdef DIAGNOSTIC
588 	if ((dmadir != DMACSR_SETREAD) && (dmadir != DMACSR_SETWRITE)) {
589 		panic("DMA: nextdma_start(), dmadir arg must be DMACSR_SETREAD or DMACSR_SETWRITE\n");
590 	}
591 #endif
592 
593 	/* preload both the current and the continue maps */
594 	next_dma_rotate(nd);
595 
596 #ifdef DIAGNOSTIC
597 	if (!nd->_nd_map_cont) {
598 		panic("No map available in nextdma_start()");
599 	}
600 #endif
601 
602 	next_dma_rotate(nd);
603 
604 	DPRINTF(("DMA initiating DMA %s of %d segments on intr(0x%b)\n",
605 			(dmadir == DMACSR_SETREAD ? "read" : "write"), nd->_nd_map->dm_nsegs,
606 			NEXT_I_BIT(nd->nd_intr),NEXT_INTR_BITS));
607 
608 	bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_CSR, 0);
609 	bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_CSR,
610 			DMACSR_INITBUF | DMACSR_RESET | dmadir);
611 
612 	next_dma_setup_curr_regs(nd);
613 	next_dma_setup_cont_regs(nd);
614 
615 #if (defined(ND_DEBUG))
616 	if (nextdma_debug) next_dma_print(nd);
617 #endif
618 
619 	if ((nd->_nd_map_cont == NULL) && (nd->_nd_idx+1 == nd->_nd_map->dm_nsegs)) {
620 		bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_CSR,
621 				DMACSR_SETENABLE | dmadir);
622 	} else {
623 		bus_space_write_4(nd->nd_bst, nd->nd_bsh, DD_CSR,
624 				DMACSR_SETSUPDATE | DMACSR_SETENABLE | dmadir);
625 	}
626 }
627