xref: /dflybsd-src/sys/kern/subr_rman.c (revision 2d12c69a9e8f519ee15ef19279e83041cf427ad3)
1 /*
2  * Copyright 1998 Massachusetts Institute of Technology
3  *
4  * Permission to use, copy, modify, and distribute this software and
5  * its documentation for any purpose and without fee is hereby
6  * granted, provided that both the above copyright notice and this
7  * permission notice appear in all copies, that both the above
8  * copyright notice and this permission notice appear in all
9  * supporting documentation, and that the name of M.I.T. not be used
10  * in advertising or publicity pertaining to distribution of the
11  * software without specific, written prior permission.  M.I.T. makes
12  * no representations about the suitability of this software for any
13  * purpose.  It is provided "as is" without express or implied
14  * warranty.
15  *
16  * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
17  * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
18  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
20  * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
23  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
25  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
26  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  * $FreeBSD: src/sys/kern/subr_rman.c,v 1.10.2.1 2001/06/05 08:06:08 imp Exp $
30  * $DragonFly: src/sys/kern/subr_rman.c,v 1.15 2008/09/30 12:20:29 hasso Exp $
31  */
32 
33 /*
34  * The kernel resource manager.  This code is responsible for keeping track
35  * of hardware resources which are apportioned out to various drivers.
36  * It does not actually assign those resources, and it is not expected
37  * that end-device drivers will call into this code directly.  Rather,
38  * the code which implements the buses that those devices are attached to,
39  * and the code which manages CPU resources, will call this code, and the
40  * end-device drivers will make upcalls to that code to actually perform
41  * the allocation.
42  *
43  * There are two sorts of resources managed by this code.  The first is
44  * the more familiar array (RMAN_ARRAY) type; resources in this class
45  * consist of a sequence of individually-allocatable objects which have
46  * been numbered in some well-defined order.  Most of the resources
47  * are of this type, as it is the most familiar.  The second type is
48  * called a gauge (RMAN_GAUGE), and models fungible resources (i.e.,
49  * resources in which each instance is indistinguishable from every
50  * other instance).  The principal anticipated application of gauges
51  * is in the context of power consumption, where a bus may have a specific
52  * power budget which all attached devices share.  RMAN_GAUGE is not
53  * implemented yet.
54  *
55  * For array resources, we make one simplifying assumption: two clients
56  * sharing the same resource must use the same range of indices.  That
57  * is to say, sharing of overlapping-but-not-identical regions is not
58  * permitted.
59  */
60 
61 #include <sys/param.h>
62 #include <sys/systm.h>
63 #include <sys/kernel.h>
64 #include <sys/lock.h>
65 #include <sys/malloc.h>
66 #include <sys/bus.h>		/* XXX debugging */
67 #include <sys/rman.h>
68 #include <sys/sysctl.h>
69 
70 int	rman_debug = 0;
71 TUNABLE_INT("debug.rman_debug", &rman_debug);
72 SYSCTL_INT(_debug, OID_AUTO, rman_debug, CTLFLAG_RW,
73     &rman_debug, 0, "rman debug");
74 
75 #define DPRINTF(params) if (rman_debug) kprintf params
76 
77 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
78 
79 struct	rman_head rman_head;
80 static	struct lwkt_token rman_tok; /* mutex to protect rman_head */
81 static	int int_rman_activate_resource(struct rman *rm, struct resource *r,
82 				       struct resource **whohas);
83 static	int int_rman_deactivate_resource(struct resource *r);
84 static	int int_rman_release_resource(struct rman *rm, struct resource *r);
85 
86 int
87 rman_init(struct rman *rm, int cpuid)
88 {
89 	static int once;
90 
91 	if (once == 0) {
92 		once = 1;
93 		TAILQ_INIT(&rman_head);
94 		lwkt_token_init(&rman_tok, "rman");
95 	}
96 
97 	if (rm->rm_type == RMAN_UNINIT)
98 		panic("rman_init");
99 	if (rm->rm_type == RMAN_GAUGE)
100 		panic("implement RMAN_GAUGE");
101 
102 	TAILQ_INIT(&rm->rm_list);
103 	rm->rm_slock = kmalloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
104 	if (rm->rm_slock == NULL)
105 		return ENOMEM;
106 	lwkt_token_init(rm->rm_slock, "rmanslock");
107 
108 	rm->rm_cpuid = cpuid;
109 
110 	lwkt_gettoken(&rman_tok);
111 	TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
112 	lwkt_reltoken(&rman_tok);
113 	return 0;
114 }
115 
116 /*
117  * NB: this interface is not robust against programming errors which
118  * add multiple copies of the same region.
119  */
120 int
121 rman_manage_region(struct rman *rm, u_long start, u_long end)
122 {
123 	struct resource *r, *s;
124 
125 	DPRINTF(("rman_manage_region: <%s> request: start %#lx, end %#lx\n",
126 	    rm->rm_descr, start, end));
127 	r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT | M_ZERO);
128 	if (r == 0)
129 		return ENOMEM;
130 	r->r_sharehead = 0;
131 	r->r_start = start;
132 	r->r_end = end;
133 	r->r_flags = 0;
134 	r->r_dev = 0;
135 	r->r_rm = rm;
136 
137 	lwkt_gettoken(rm->rm_slock);
138 	for (s = TAILQ_FIRST(&rm->rm_list);
139 	     s && s->r_end < r->r_start;
140 	     s = TAILQ_NEXT(s, r_link))
141 		;
142 
143 	if (s == NULL)
144 		TAILQ_INSERT_TAIL(&rm->rm_list, r, r_link);
145 	else
146 		TAILQ_INSERT_BEFORE(s, r, r_link);
147 
148 	lwkt_reltoken(rm->rm_slock);
149 	return 0;
150 }
151 
152 int
153 rman_fini(struct rman *rm)
154 {
155 	struct resource *r;
156 
157 	lwkt_gettoken(rm->rm_slock);
158 	TAILQ_FOREACH(r, &rm->rm_list, r_link) {
159 		if (r->r_flags & RF_ALLOCATED) {
160 			lwkt_reltoken(rm->rm_slock);
161 			return EBUSY;
162 		}
163 	}
164 
165 	/*
166 	 * There really should only be one of these if we are in this
167 	 * state and the code is working properly, but it can't hurt.
168 	 */
169 	while (!TAILQ_EMPTY(&rm->rm_list)) {
170 		r = TAILQ_FIRST(&rm->rm_list);
171 		TAILQ_REMOVE(&rm->rm_list, r, r_link);
172 		kfree(r, M_RMAN);
173 	}
174 	lwkt_reltoken(rm->rm_slock);
175 
176 	/* XXX what's the point of this if we are going to free the struct? */
177 	lwkt_gettoken(&rman_tok);
178 	TAILQ_REMOVE(&rman_head, rm, rm_link);
179 	lwkt_reltoken(&rman_tok);
180 	kfree(rm->rm_slock, M_RMAN);
181 
182 	return 0;
183 }
184 
185 struct resource *
186 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
187 		      u_int flags, struct device *dev)
188 {
189 	u_int	want_activate;
190 	struct	resource *r, *s, *rv;
191 	u_long	rstart, rend;
192 
193 	rv = 0;
194 
195 	DPRINTF(("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
196 	       "%#lx, flags %u, device %s\n", rm->rm_descr, start, end,
197 	       count, flags,
198 	       dev == NULL ? "<null>" : device_get_nameunit(dev)));
199 	want_activate = (flags & RF_ACTIVE);
200 	flags &= ~RF_ACTIVE;
201 
202 	lwkt_gettoken(rm->rm_slock);
203 
204 	for (r = TAILQ_FIRST(&rm->rm_list);
205 	     r && r->r_end < start;
206 	     r = TAILQ_NEXT(r, r_link))
207 		;
208 
209 	if (r == NULL) {
210 		DPRINTF(("could not find a region\n"));
211 		goto out;
212 	}
213 
214 	/*
215 	 * First try to find an acceptable totally-unshared region.
216 	 */
217 	for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
218 		DPRINTF(("considering [%#lx, %#lx]\n", s->r_start, s->r_end));
219 		if (s->r_start > end) {
220 			DPRINTF(("s->r_start (%#lx) > end (%#lx)\n",
221 			    s->r_start, end));
222 			break;
223 		}
224 		if (s->r_flags & RF_ALLOCATED) {
225 			DPRINTF(("region is allocated\n"));
226 			continue;
227 		}
228 		rstart = max(s->r_start, start);
229 		rstart = (rstart + ((1ul << RF_ALIGNMENT(flags))) - 1) &
230 		    ~((1ul << RF_ALIGNMENT(flags)) - 1);
231 		rend = min(s->r_end, max(start + count, end));
232 		DPRINTF(("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
233 		       rstart, rend, (rend - rstart + 1), count));
234 
235 		if ((rend - rstart + 1) >= count) {
236 			DPRINTF(("candidate region: [%#lx, %#lx], size %#lx\n",
237 			       rstart, rend, (rend - rstart + 1)));
238 			if ((s->r_end - s->r_start + 1) == count) {
239 				DPRINTF(("candidate region is entire chunk\n"));
240 				rv = s;
241 				rv->r_flags |= RF_ALLOCATED | flags;
242 				rv->r_dev = dev;
243 				goto out;
244 			}
245 
246 			/*
247 			 * If s->r_start < rstart and
248 			 *    s->r_end > rstart + count - 1, then
249 			 * we need to split the region into three pieces
250 			 * (the middle one will get returned to the user).
251 			 * Otherwise, we are allocating at either the
252 			 * beginning or the end of s, so we only need to
253 			 * split it in two.  The first case requires
254 			 * two new allocations; the second requires but one.
255 			 */
256 			rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO);
257 			if (rv == 0)
258 				goto out;
259 			rv->r_start = rstart;
260 			rv->r_end = rstart + count - 1;
261 			rv->r_flags = flags | RF_ALLOCATED;
262 			rv->r_dev = dev;
263 			rv->r_sharehead = 0;
264 			rv->r_rm = rm;
265 
266 			if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
267 				DPRINTF(("splitting region in three parts: "
268 				       "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
269 				       s->r_start, rv->r_start - 1,
270 				       rv->r_start, rv->r_end,
271 				       rv->r_end + 1, s->r_end));
272 				/*
273 				 * We are allocating in the middle.
274 				 */
275 				r = kmalloc(sizeof *r, M_RMAN,
276 				    M_NOWAIT | M_ZERO);
277 				if (r == 0) {
278 					kfree(rv, M_RMAN);
279 					rv = 0;
280 					goto out;
281 				}
282 				r->r_start = rv->r_end + 1;
283 				r->r_end = s->r_end;
284 				r->r_flags = s->r_flags;
285 				r->r_dev = 0;
286 				r->r_sharehead = 0;
287 				r->r_rm = rm;
288 				s->r_end = rv->r_start - 1;
289 				TAILQ_INSERT_AFTER(&rm->rm_list, s, rv,
290 						     r_link);
291 				TAILQ_INSERT_AFTER(&rm->rm_list, rv, r,
292 						     r_link);
293 			} else if (s->r_start == rv->r_start) {
294 				DPRINTF(("allocating from the beginning\n"));
295 				/*
296 				 * We are allocating at the beginning.
297 				 */
298 				s->r_start = rv->r_end + 1;
299 				TAILQ_INSERT_BEFORE(s, rv, r_link);
300 			} else {
301 				DPRINTF(("allocating at the end\n"));
302 				/*
303 				 * We are allocating at the end.
304 				 */
305 				s->r_end = rv->r_start - 1;
306 				TAILQ_INSERT_AFTER(&rm->rm_list, s, rv,
307 						     r_link);
308 			}
309 			goto out;
310 		}
311 	}
312 
313 	/*
314 	 * Now find an acceptable shared region, if the client's requirements
315 	 * allow sharing.  By our implementation restriction, a candidate
316 	 * region must match exactly by both size and sharing type in order
317 	 * to be considered compatible with the client's request.  (The
318 	 * former restriction could probably be lifted without too much
319 	 * additional work, but this does not seem warranted.)
320 	 */
321 	DPRINTF(("no unshared regions found\n"));
322 	if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
323 		goto out;
324 
325 	for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
326 		if (s->r_start > end)
327 			break;
328 		if ((s->r_flags & flags) != flags)
329 			continue;
330 		rstart = max(s->r_start, start);
331 		rend = min(s->r_end, max(start + count, end));
332 		if (s->r_start >= start && s->r_end <= end
333 		    && (s->r_end - s->r_start + 1) == count) {
334 			rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO);
335 			if (rv == 0)
336 				goto out;
337 			rv->r_start = s->r_start;
338 			rv->r_end = s->r_end;
339 			rv->r_flags = s->r_flags &
340 				(RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
341 			rv->r_dev = dev;
342 			rv->r_rm = rm;
343 			if (s->r_sharehead == 0) {
344 				s->r_sharehead = kmalloc(sizeof *s->r_sharehead,
345 							M_RMAN,
346 							M_NOWAIT | M_ZERO);
347 				if (s->r_sharehead == 0) {
348 					kfree(rv, M_RMAN);
349 					rv = 0;
350 					goto out;
351 				}
352 				LIST_INIT(s->r_sharehead);
353 				LIST_INSERT_HEAD(s->r_sharehead, s,
354 						 r_sharelink);
355 				s->r_flags |= RF_FIRSTSHARE;
356 			}
357 			rv->r_sharehead = s->r_sharehead;
358 			LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
359 			goto out;
360 		}
361 	}
362 
363 	/*
364 	 * We couldn't find anything.
365 	 */
366 out:
367 	/*
368 	 * If the user specified RF_ACTIVE in the initial flags,
369 	 * which is reflected in `want_activate', we attempt to atomically
370 	 * activate the resource.  If this fails, we release the resource
371 	 * and indicate overall failure.  (This behavior probably doesn't
372 	 * make sense for RF_TIMESHARE-type resources.)
373 	 */
374 	if (rv && want_activate) {
375 		struct resource *whohas;
376 		if (int_rman_activate_resource(rm, rv, &whohas)) {
377 			int_rman_release_resource(rm, rv);
378 			rv = 0;
379 		}
380 	}
381 	lwkt_reltoken(rm->rm_slock);
382 	return (rv);
383 }
384 
385 static int
386 int_rman_activate_resource(struct rman *rm, struct resource *r,
387 			   struct resource **whohas)
388 {
389 	struct resource *s;
390 	int ok;
391 
392 	/*
393 	 * If we are not timesharing, then there is nothing much to do.
394 	 * If we already have the resource, then there is nothing at all to do.
395 	 * If we are not on a sharing list with anybody else, then there is
396 	 * little to do.
397 	 */
398 	if ((r->r_flags & RF_TIMESHARE) == 0
399 	    || (r->r_flags & RF_ACTIVE) != 0
400 	    || r->r_sharehead == 0) {
401 		r->r_flags |= RF_ACTIVE;
402 		return 0;
403 	}
404 
405 	ok = 1;
406 	for (s = LIST_FIRST(r->r_sharehead); s && ok;
407 	     s = LIST_NEXT(s, r_sharelink)) {
408 		if ((s->r_flags & RF_ACTIVE) != 0) {
409 			ok = 0;
410 			*whohas = s;
411 		}
412 	}
413 	if (ok) {
414 		r->r_flags |= RF_ACTIVE;
415 		return 0;
416 	}
417 	return EBUSY;
418 }
419 
420 int
421 rman_activate_resource(struct resource *r)
422 {
423 	int rv;
424 	struct resource *whohas;
425 	struct rman *rm;
426 
427 	rm = r->r_rm;
428 	lwkt_gettoken(rm->rm_slock);
429 	rv = int_rman_activate_resource(rm, r, &whohas);
430 	lwkt_reltoken(rm->rm_slock);
431 	return rv;
432 }
433 
434 #if 0
435 
436 /* XXX */
437 int
438 rman_await_resource(struct resource *r, int slpflags, int timo)
439 {
440 	int	rv;
441 	struct	resource *whohas;
442 	struct	rman *rm;
443 
444 	rm = r->r_rm;
445 	for (;;) {
446 		lwkt_gettoken(rm->rm_slock);
447 		rv = int_rman_activate_resource(rm, r, &whohas);
448 		if (rv != EBUSY)
449 			return (rv);	/* returns with ilock held */
450 
451 		if (r->r_sharehead == 0)
452 			panic("rman_await_resource");
453 		/*
454 		 * A critical section will hopefully will prevent a race
455 		 * between lwkt_reltoken and tsleep where a process
456 		 * could conceivably get in and release the resource
457 		 * before we have a chance to sleep on it. YYY
458 		 */
459 		crit_enter();
460 		whohas->r_flags |= RF_WANTED;
461 		rv = tsleep(r->r_sharehead, slpflags, "rmwait", timo);
462 		if (rv) {
463 			lwkt_reltoken(rm->rm_slock);
464 			crit_exit();
465 			return rv;
466 		}
467 		crit_exit();
468 	}
469 }
470 
471 #endif
472 
473 static int
474 int_rman_deactivate_resource(struct resource *r)
475 {
476 	struct	rman *rm;
477 
478 	rm = r->r_rm;
479 	r->r_flags &= ~RF_ACTIVE;
480 	if (r->r_flags & RF_WANTED) {
481 		r->r_flags &= ~RF_WANTED;
482 		wakeup(r->r_sharehead);
483 	}
484 	return 0;
485 }
486 
487 int
488 rman_deactivate_resource(struct resource *r)
489 {
490 	struct rman *rm;
491 
492 	rm = r->r_rm;
493 	lwkt_gettoken(rm->rm_slock);
494 	int_rman_deactivate_resource(r);
495 	lwkt_reltoken(rm->rm_slock);
496 	return 0;
497 }
498 
499 static int
500 int_rman_release_resource(struct rman *rm, struct resource *r)
501 {
502 	struct	resource *s, *t;
503 
504 	if (r->r_flags & RF_ACTIVE)
505 		int_rman_deactivate_resource(r);
506 
507 	/*
508 	 * Check for a sharing list first.  If there is one, then we don't
509 	 * have to think as hard.
510 	 */
511 	if (r->r_sharehead) {
512 		/*
513 		 * If a sharing list exists, then we know there are at
514 		 * least two sharers.
515 		 *
516 		 * If we are in the main circleq, appoint someone else.
517 		 */
518 		LIST_REMOVE(r, r_sharelink);
519 		s = LIST_FIRST(r->r_sharehead);
520 		if (r->r_flags & RF_FIRSTSHARE) {
521 			s->r_flags |= RF_FIRSTSHARE;
522 			TAILQ_INSERT_BEFORE(r, s, r_link);
523 			TAILQ_REMOVE(&rm->rm_list, r, r_link);
524 		}
525 
526 		/*
527 		 * Make sure that the sharing list goes away completely
528 		 * if the resource is no longer being shared at all.
529 		 */
530 		if (LIST_NEXT(s, r_sharelink) == 0) {
531 			kfree(s->r_sharehead, M_RMAN);
532 			s->r_sharehead = 0;
533 			s->r_flags &= ~RF_FIRSTSHARE;
534 		}
535 		goto out;
536 	}
537 
538 	/*
539 	 * Look at the adjacent resources in the list and see if our
540 	 * segment can be merged with any of them.
541 	 */
542 	s = TAILQ_PREV(r, resource_head, r_link);
543 	t = TAILQ_NEXT(r, r_link);
544 
545 	if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0
546 	    && t != NULL && (t->r_flags & RF_ALLOCATED) == 0) {
547 		/*
548 		 * Merge all three segments.
549 		 */
550 		s->r_end = t->r_end;
551 		TAILQ_REMOVE(&rm->rm_list, r, r_link);
552 		TAILQ_REMOVE(&rm->rm_list, t, r_link);
553 		kfree(t, M_RMAN);
554 	} else if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0) {
555 		/*
556 		 * Merge previous segment with ours.
557 		 */
558 		s->r_end = r->r_end;
559 		TAILQ_REMOVE(&rm->rm_list, r, r_link);
560 	} else if (t != NULL && (t->r_flags & RF_ALLOCATED) == 0) {
561 		/*
562 		 * Merge next segment with ours.
563 		 */
564 		t->r_start = r->r_start;
565 		TAILQ_REMOVE(&rm->rm_list, r, r_link);
566 	} else {
567 		/*
568 		 * At this point, we know there is nothing we
569 		 * can potentially merge with, because on each
570 		 * side, there is either nothing there or what is
571 		 * there is still allocated.  In that case, we don't
572 		 * want to remove r from the list; we simply want to
573 		 * change it to an unallocated region and return
574 		 * without freeing anything.
575 		 */
576 		r->r_flags &= ~RF_ALLOCATED;
577 		return 0;
578 	}
579 
580 out:
581 	kfree(r, M_RMAN);
582 	return 0;
583 }
584 
585 int
586 rman_release_resource(struct resource *r)
587 {
588 	struct	rman *rm = r->r_rm;
589 	int	rv;
590 
591 	lwkt_gettoken(rm->rm_slock);
592 	rv = int_rman_release_resource(rm, r);
593 	lwkt_reltoken(rm->rm_slock);
594 	return (rv);
595 }
596 
597 uint32_t
598 rman_make_alignment_flags(uint32_t size)
599 {
600 	int	i;
601 
602 	/*
603 	 * Find the hightest bit set, and add one if more than one bit
604 	 * set.  We're effectively computing the ceil(log2(size)) here.
605 	 */
606 	for (i = 32; i > 0; i--)
607 		if ((1 << i) & size)
608 			break;
609 	if (~(1 << i) & size)
610 		i++;
611 
612 	return(RF_ALIGNMENT_LOG2(i));
613 }
614 
615 /*
616  * Sysctl interface for scanning the resource lists.
617  *
618  * We take two input parameters; the index into the list of resource
619  * managers, and the resource offset into the list.
620  */
621 static int
622 sysctl_rman(SYSCTL_HANDLER_ARGS)
623 {
624 	int			*name = (int *)arg1;
625 	u_int			namelen = arg2;
626 	int			rman_idx, res_idx;
627 	struct rman		*rm;
628 	struct resource		*res;
629 	struct u_rman		urm;
630 	struct u_resource	ures;
631 	int			error;
632 
633 	if (namelen != 3)
634 		return (EINVAL);
635 
636 	if (bus_data_generation_check(name[0]))
637 		return (EINVAL);
638 	rman_idx = name[1];
639 	res_idx = name[2];
640 
641 	/*
642 	 * Find the indexed resource manager
643 	 */
644 	TAILQ_FOREACH(rm, &rman_head, rm_link) {
645 		if (rman_idx-- == 0)
646 			break;
647 	}
648 	if (rm == NULL)
649 		return (ENOENT);
650 
651 	/*
652 	 * If the resource index is -1, we want details on the
653 	 * resource manager.
654 	 */
655 	if (res_idx == -1) {
656 		urm.rm_handle = (uintptr_t)rm;
657 		strlcpy(urm.rm_descr, rm->rm_descr, RM_TEXTLEN);
658 		urm.rm_start = rm->rm_start;
659 		urm.rm_size = rm->rm_end - rm->rm_start + 1;
660 		urm.rm_type = rm->rm_type;
661 
662 		error = SYSCTL_OUT(req, &urm, sizeof(urm));
663 		return (error);
664 	}
665 
666 	/*
667 	 * Find the indexed resource and return it.
668 	 */
669 	TAILQ_FOREACH(res, &rm->rm_list, r_link) {
670 		if (res_idx-- == 0) {
671 			ures.r_handle = (uintptr_t)res;
672 			ures.r_parent = (uintptr_t)res->r_rm;
673 			ures.r_device = (uintptr_t)res->r_dev;
674 			if (res->r_dev != NULL) {
675 				if (device_get_name(res->r_dev) != NULL) {
676 					ksnprintf(ures.r_devname, RM_TEXTLEN,
677 					    "%s%d",
678 					    device_get_name(res->r_dev),
679 					    device_get_unit(res->r_dev));
680 				} else {
681 					strlcpy(ures.r_devname, "nomatch",
682 					    RM_TEXTLEN);
683 				}
684 			} else {
685 				ures.r_devname[0] = '\0';
686 			}
687 			ures.r_start = res->r_start;
688 			ures.r_size = res->r_end - res->r_start + 1;
689 			ures.r_flags = res->r_flags;
690 
691 			error = SYSCTL_OUT(req, &ures, sizeof(ures));
692 			return (error);
693 		}
694 	}
695 	return (ENOENT);
696 }
697 
698 SYSCTL_NODE(_hw_bus, OID_AUTO, rman, CTLFLAG_RD, sysctl_rman,
699     "kernel resource manager");
700