xref: /freebsd/sys/kern/subr_rman.c (revision 7bd6fde3)
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 
30 /*
31  * The kernel resource manager.  This code is responsible for keeping track
32  * of hardware resources which are apportioned out to various drivers.
33  * It does not actually assign those resources, and it is not expected
34  * that end-device drivers will call into this code directly.  Rather,
35  * the code which implements the buses that those devices are attached to,
36  * and the code which manages CPU resources, will call this code, and the
37  * end-device drivers will make upcalls to that code to actually perform
38  * the allocation.
39  *
40  * There are two sorts of resources managed by this code.  The first is
41  * the more familiar array (RMAN_ARRAY) type; resources in this class
42  * consist of a sequence of individually-allocatable objects which have
43  * been numbered in some well-defined order.  Most of the resources
44  * are of this type, as it is the most familiar.  The second type is
45  * called a gauge (RMAN_GAUGE), and models fungible resources (i.e.,
46  * resources in which each instance is indistinguishable from every
47  * other instance).  The principal anticipated application of gauges
48  * is in the context of power consumption, where a bus may have a specific
49  * power budget which all attached devices share.  RMAN_GAUGE is not
50  * implemented yet.
51  *
52  * For array resources, we make one simplifying assumption: two clients
53  * sharing the same resource must use the same range of indices.  That
54  * is to say, sharing of overlapping-but-not-identical regions is not
55  * permitted.
56  */
57 
58 #include <sys/cdefs.h>
59 __FBSDID("$FreeBSD$");
60 
61 #include <sys/param.h>
62 #include <sys/systm.h>
63 #include <sys/kernel.h>
64 #include <sys/limits.h>
65 #include <sys/lock.h>
66 #include <sys/malloc.h>
67 #include <sys/mutex.h>
68 #include <sys/bus.h>		/* XXX debugging */
69 #include <machine/bus.h>
70 #include <sys/rman.h>
71 #include <sys/sysctl.h>
72 
73 /*
74  * We use a linked list rather than a bitmap because we need to be able to
75  * represent potentially huge objects (like all of a processor's physical
76  * address space).  That is also why the indices are defined to have type
77  * `unsigned long' -- that being the largest integral type in ISO C (1990).
78  * The 1999 version of C allows `long long'; we may need to switch to that
79  * at some point in the future, particularly if we want to support 36-bit
80  * addresses on IA32 hardware.
81  */
82 struct resource_i {
83 	struct resource		r_r;
84 	TAILQ_ENTRY(resource_i)	r_link;
85 	LIST_ENTRY(resource_i)	r_sharelink;
86 	LIST_HEAD(, resource_i)	*r_sharehead;
87 	u_long	r_start;	/* index of the first entry in this resource */
88 	u_long	r_end;		/* index of the last entry (inclusive) */
89 	u_int	r_flags;
90 	void	*r_virtual;	/* virtual address of this resource */
91 	struct	device *r_dev;	/* device which has allocated this resource */
92 	struct	rman *r_rm;	/* resource manager from whence this came */
93 	int	r_rid;		/* optional rid for this resource. */
94 };
95 
96 int     rman_debug = 0;
97 TUNABLE_INT("debug.rman_debug", &rman_debug);
98 SYSCTL_INT(_debug, OID_AUTO, rman_debug, CTLFLAG_RW,
99     &rman_debug, 0, "rman debug");
100 
101 #define DPRINTF(params) if (rman_debug) printf params
102 
103 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
104 
105 struct	rman_head rman_head;
106 static	struct mtx rman_mtx; /* mutex to protect rman_head */
107 static	int int_rman_activate_resource(struct rman *rm, struct resource_i *r,
108 				       struct resource_i **whohas);
109 static	int int_rman_deactivate_resource(struct resource_i *r);
110 static	int int_rman_release_resource(struct rman *rm, struct resource_i *r);
111 
112 static __inline struct resource_i *
113 int_alloc_resource(int malloc_flag)
114 {
115 	struct resource_i *r;
116 
117 	r = malloc(sizeof *r, M_RMAN, malloc_flag | M_ZERO);
118 	if (r != NULL) {
119 		r->r_r.__r_i = r;
120 	}
121 	return (r);
122 }
123 
124 int
125 rman_init(struct rman *rm)
126 {
127 	static int once = 0;
128 
129 	if (once == 0) {
130 		once = 1;
131 		TAILQ_INIT(&rman_head);
132 		mtx_init(&rman_mtx, "rman head", NULL, MTX_DEF);
133 	}
134 
135 	if (rm->rm_type == RMAN_UNINIT)
136 		panic("rman_init");
137 	if (rm->rm_type == RMAN_GAUGE)
138 		panic("implement RMAN_GAUGE");
139 
140 	TAILQ_INIT(&rm->rm_list);
141 	rm->rm_mtx = malloc(sizeof *rm->rm_mtx, M_RMAN, M_NOWAIT | M_ZERO);
142 	if (rm->rm_mtx == NULL)
143 		return ENOMEM;
144 	mtx_init(rm->rm_mtx, "rman", NULL, MTX_DEF);
145 
146 	mtx_lock(&rman_mtx);
147 	TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
148 	mtx_unlock(&rman_mtx);
149 	return 0;
150 }
151 
152 /*
153  * NB: this interface is not robust against programming errors which
154  * add multiple copies of the same region.
155  */
156 int
157 rman_manage_region(struct rman *rm, u_long start, u_long end)
158 {
159 	struct resource_i *r, *s, *t;
160 
161 	DPRINTF(("rman_manage_region: <%s> request: start %#lx, end %#lx\n",
162 	    rm->rm_descr, start, end));
163 	r = int_alloc_resource(M_NOWAIT);
164 	if (r == NULL)
165 		return ENOMEM;
166 	r->r_start = start;
167 	r->r_end = end;
168 	r->r_rm = rm;
169 
170 	mtx_lock(rm->rm_mtx);
171 
172 	/* Skip entries before us. */
173 	TAILQ_FOREACH(s, &rm->rm_list, r_link) {
174 		if (s->r_end == ULONG_MAX)
175 			break;
176 		if (s->r_end + 1 >= r->r_start)
177 			break;
178 	}
179 
180 	/* If we ran off the end of the list, insert at the tail. */
181 	if (s == NULL) {
182 		TAILQ_INSERT_TAIL(&rm->rm_list, r, r_link);
183 	} else {
184 		/* Check for any overlap with the current region. */
185 		if (r->r_start <= s->r_end && r->r_end >= s->r_start)
186 			return EBUSY;
187 
188 		/* Check for any overlap with the next region. */
189 		t = TAILQ_NEXT(s, r_link);
190 		if (t && r->r_start <= t->r_end && r->r_end >= t->r_start)
191 			return EBUSY;
192 
193 		/*
194 		 * See if this region can be merged with the next region.  If
195 		 * not, clear the pointer.
196 		 */
197 		if (t && (r->r_end + 1 != t->r_start || t->r_flags != 0))
198 			t = NULL;
199 
200 		/* See if we can merge with the current region. */
201 		if (s->r_end + 1 == r->r_start && s->r_flags == 0) {
202 			/* Can we merge all 3 regions? */
203 			if (t != NULL) {
204 				s->r_end = t->r_end;
205 				TAILQ_REMOVE(&rm->rm_list, t, r_link);
206 				free(r, M_RMAN);
207 				free(t, M_RMAN);
208 			} else {
209 				s->r_end = r->r_end;
210 				free(r, M_RMAN);
211 			}
212 		} else if (t != NULL) {
213 			/* Can we merge with just the next region? */
214 			t->r_start = r->r_start;
215 			free(r, M_RMAN);
216 		} else if (s->r_end < r->r_start) {
217 			TAILQ_INSERT_AFTER(&rm->rm_list, s, r, r_link);
218 		} else {
219 			TAILQ_INSERT_BEFORE(s, r, r_link);
220 		}
221 	}
222 
223 	mtx_unlock(rm->rm_mtx);
224 	return 0;
225 }
226 
227 int
228 rman_init_from_resource(struct rman *rm, struct resource *r)
229 {
230 	int rv;
231 
232 	if ((rv = rman_init(rm)) != 0)
233 		return (rv);
234 	return (rman_manage_region(rm, r->__r_i->r_start, r->__r_i->r_end));
235 }
236 
237 int
238 rman_fini(struct rman *rm)
239 {
240 	struct resource_i *r;
241 
242 	mtx_lock(rm->rm_mtx);
243 	TAILQ_FOREACH(r, &rm->rm_list, r_link) {
244 		if (r->r_flags & RF_ALLOCATED) {
245 			mtx_unlock(rm->rm_mtx);
246 			return EBUSY;
247 		}
248 	}
249 
250 	/*
251 	 * There really should only be one of these if we are in this
252 	 * state and the code is working properly, but it can't hurt.
253 	 */
254 	while (!TAILQ_EMPTY(&rm->rm_list)) {
255 		r = TAILQ_FIRST(&rm->rm_list);
256 		TAILQ_REMOVE(&rm->rm_list, r, r_link);
257 		free(r, M_RMAN);
258 	}
259 	mtx_unlock(rm->rm_mtx);
260 	mtx_lock(&rman_mtx);
261 	TAILQ_REMOVE(&rman_head, rm, rm_link);
262 	mtx_unlock(&rman_mtx);
263 	mtx_destroy(rm->rm_mtx);
264 	free(rm->rm_mtx, M_RMAN);
265 
266 	return 0;
267 }
268 
269 struct resource *
270 rman_reserve_resource_bound(struct rman *rm, u_long start, u_long end,
271 		      u_long count, u_long bound,  u_int flags,
272 		      struct device *dev)
273 {
274 	u_int	want_activate;
275 	struct	resource_i *r, *s, *rv;
276 	u_long	rstart, rend, amask, bmask;
277 
278 	rv = NULL;
279 
280 	DPRINTF(("rman_reserve_resource_bound: <%s> request: [%#lx, %#lx], "
281 	       "length %#lx, flags %u, device %s\n", rm->rm_descr, start, end,
282 	       count, flags,
283 	       dev == NULL ? "<null>" : device_get_nameunit(dev)));
284 	want_activate = (flags & RF_ACTIVE);
285 	flags &= ~RF_ACTIVE;
286 
287 	mtx_lock(rm->rm_mtx);
288 
289 	for (r = TAILQ_FIRST(&rm->rm_list);
290 	     r && r->r_end < start;
291 	     r = TAILQ_NEXT(r, r_link))
292 		;
293 
294 	if (r == NULL) {
295 		DPRINTF(("could not find a region\n"));
296 		goto out;
297 	}
298 
299 	amask = (1ul << RF_ALIGNMENT(flags)) - 1;
300 	/* If bound is 0, bmask will also be 0 */
301 	bmask = ~(bound - 1);
302 	/*
303 	 * First try to find an acceptable totally-unshared region.
304 	 */
305 	for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
306 		DPRINTF(("considering [%#lx, %#lx]\n", s->r_start, s->r_end));
307 		if (s->r_start + count - 1 > end) {
308 			DPRINTF(("s->r_start (%#lx) + count - 1> end (%#lx)\n",
309 			    s->r_start, end));
310 			break;
311 		}
312 		if (s->r_flags & RF_ALLOCATED) {
313 			DPRINTF(("region is allocated\n"));
314 			continue;
315 		}
316 		rstart = ulmax(s->r_start, start);
317 		/*
318 		 * Try to find a region by adjusting to boundary and alignment
319 		 * until both conditions are satisfied. This is not an optimal
320 		 * algorithm, but in most cases it isn't really bad, either.
321 		 */
322 		do {
323 			rstart = (rstart + amask) & ~amask;
324 			if (((rstart ^ (rstart + count - 1)) & bmask) != 0)
325 				rstart += bound - (rstart & ~bmask);
326 		} while ((rstart & amask) != 0 && rstart < end &&
327 		    rstart < s->r_end);
328 		rend = ulmin(s->r_end, ulmax(rstart + count - 1, end));
329 		if (rstart > rend) {
330 			DPRINTF(("adjusted start exceeds end\n"));
331 			continue;
332 		}
333 		DPRINTF(("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
334 		       rstart, rend, (rend - rstart + 1), count));
335 
336 		if ((rend - rstart + 1) >= count) {
337 			DPRINTF(("candidate region: [%#lx, %#lx], size %#lx\n",
338 			       rstart, rend, (rend - rstart + 1)));
339 			if ((s->r_end - s->r_start + 1) == count) {
340 				DPRINTF(("candidate region is entire chunk\n"));
341 				rv = s;
342 				rv->r_flags |= RF_ALLOCATED | flags;
343 				rv->r_dev = dev;
344 				goto out;
345 			}
346 
347 			/*
348 			 * If s->r_start < rstart and
349 			 *    s->r_end > rstart + count - 1, then
350 			 * we need to split the region into three pieces
351 			 * (the middle one will get returned to the user).
352 			 * Otherwise, we are allocating at either the
353 			 * beginning or the end of s, so we only need to
354 			 * split it in two.  The first case requires
355 			 * two new allocations; the second requires but one.
356 			 */
357 			rv = int_alloc_resource(M_NOWAIT);
358 			if (rv == NULL)
359 				goto out;
360 			rv->r_start = rstart;
361 			rv->r_end = rstart + count - 1;
362 			rv->r_flags = flags | RF_ALLOCATED;
363 			rv->r_dev = dev;
364 			rv->r_rm = rm;
365 
366 			if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
367 				DPRINTF(("splitting region in three parts: "
368 				       "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
369 				       s->r_start, rv->r_start - 1,
370 				       rv->r_start, rv->r_end,
371 				       rv->r_end + 1, s->r_end));
372 				/*
373 				 * We are allocating in the middle.
374 				 */
375 				r = int_alloc_resource(M_NOWAIT);
376 				if (r == NULL) {
377 					free(rv, M_RMAN);
378 					rv = NULL;
379 					goto out;
380 				}
381 				r->r_start = rv->r_end + 1;
382 				r->r_end = s->r_end;
383 				r->r_flags = s->r_flags;
384 				r->r_rm = rm;
385 				s->r_end = rv->r_start - 1;
386 				TAILQ_INSERT_AFTER(&rm->rm_list, s, rv,
387 						     r_link);
388 				TAILQ_INSERT_AFTER(&rm->rm_list, rv, r,
389 						     r_link);
390 			} else if (s->r_start == rv->r_start) {
391 				DPRINTF(("allocating from the beginning\n"));
392 				/*
393 				 * We are allocating at the beginning.
394 				 */
395 				s->r_start = rv->r_end + 1;
396 				TAILQ_INSERT_BEFORE(s, rv, r_link);
397 			} else {
398 				DPRINTF(("allocating at the end\n"));
399 				/*
400 				 * We are allocating at the end.
401 				 */
402 				s->r_end = rv->r_start - 1;
403 				TAILQ_INSERT_AFTER(&rm->rm_list, s, rv,
404 						     r_link);
405 			}
406 			goto out;
407 		}
408 	}
409 
410 	/*
411 	 * Now find an acceptable shared region, if the client's requirements
412 	 * allow sharing.  By our implementation restriction, a candidate
413 	 * region must match exactly by both size and sharing type in order
414 	 * to be considered compatible with the client's request.  (The
415 	 * former restriction could probably be lifted without too much
416 	 * additional work, but this does not seem warranted.)
417 	 */
418 	DPRINTF(("no unshared regions found\n"));
419 	if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
420 		goto out;
421 
422 	for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
423 		if (s->r_start > end)
424 			break;
425 		if ((s->r_flags & flags) != flags)
426 			continue;
427 		rstart = ulmax(s->r_start, start);
428 		rend = ulmin(s->r_end, ulmax(start + count - 1, end));
429 		if (s->r_start >= start && s->r_end <= end
430 		    && (s->r_end - s->r_start + 1) == count &&
431 		    (s->r_start & amask) == 0 &&
432 		    ((s->r_start ^ s->r_end) & bmask) == 0) {
433 			rv = int_alloc_resource(M_NOWAIT);
434 			if (rv == NULL)
435 				goto out;
436 			rv->r_start = s->r_start;
437 			rv->r_end = s->r_end;
438 			rv->r_flags = s->r_flags &
439 				(RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
440 			rv->r_dev = dev;
441 			rv->r_rm = rm;
442 			if (s->r_sharehead == NULL) {
443 				s->r_sharehead = malloc(sizeof *s->r_sharehead,
444 						M_RMAN, M_NOWAIT | M_ZERO);
445 				if (s->r_sharehead == NULL) {
446 					free(rv, M_RMAN);
447 					rv = NULL;
448 					goto out;
449 				}
450 				LIST_INIT(s->r_sharehead);
451 				LIST_INSERT_HEAD(s->r_sharehead, s,
452 						 r_sharelink);
453 				s->r_flags |= RF_FIRSTSHARE;
454 			}
455 			rv->r_sharehead = s->r_sharehead;
456 			LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
457 			goto out;
458 		}
459 	}
460 
461 	/*
462 	 * We couldn't find anything.
463 	 */
464 out:
465 	/*
466 	 * If the user specified RF_ACTIVE in the initial flags,
467 	 * which is reflected in `want_activate', we attempt to atomically
468 	 * activate the resource.  If this fails, we release the resource
469 	 * and indicate overall failure.  (This behavior probably doesn't
470 	 * make sense for RF_TIMESHARE-type resources.)
471 	 */
472 	if (rv && want_activate) {
473 		struct resource_i *whohas;
474 		if (int_rman_activate_resource(rm, rv, &whohas)) {
475 			int_rman_release_resource(rm, rv);
476 			rv = NULL;
477 		}
478 	}
479 
480 	mtx_unlock(rm->rm_mtx);
481 	return (rv == NULL ? NULL : &rv->r_r);
482 }
483 
484 struct resource *
485 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
486 		      u_int flags, struct device *dev)
487 {
488 
489 	return (rman_reserve_resource_bound(rm, start, end, count, 0, flags,
490 	    dev));
491 }
492 
493 static int
494 int_rman_activate_resource(struct rman *rm, struct resource_i *r,
495 			   struct resource_i **whohas)
496 {
497 	struct resource_i *s;
498 	int ok;
499 
500 	/*
501 	 * If we are not timesharing, then there is nothing much to do.
502 	 * If we already have the resource, then there is nothing at all to do.
503 	 * If we are not on a sharing list with anybody else, then there is
504 	 * little to do.
505 	 */
506 	if ((r->r_flags & RF_TIMESHARE) == 0
507 	    || (r->r_flags & RF_ACTIVE) != 0
508 	    || r->r_sharehead == NULL) {
509 		r->r_flags |= RF_ACTIVE;
510 		return 0;
511 	}
512 
513 	ok = 1;
514 	for (s = LIST_FIRST(r->r_sharehead); s && ok;
515 	     s = LIST_NEXT(s, r_sharelink)) {
516 		if ((s->r_flags & RF_ACTIVE) != 0) {
517 			ok = 0;
518 			*whohas = s;
519 		}
520 	}
521 	if (ok) {
522 		r->r_flags |= RF_ACTIVE;
523 		return 0;
524 	}
525 	return EBUSY;
526 }
527 
528 int
529 rman_activate_resource(struct resource *re)
530 {
531 	int rv;
532 	struct resource_i *r, *whohas;
533 	struct rman *rm;
534 
535 	r = re->__r_i;
536 	rm = r->r_rm;
537 	mtx_lock(rm->rm_mtx);
538 	rv = int_rman_activate_resource(rm, r, &whohas);
539 	mtx_unlock(rm->rm_mtx);
540 	return rv;
541 }
542 
543 int
544 rman_await_resource(struct resource *re, int pri, int timo)
545 {
546 	int	rv;
547 	struct	resource_i *r, *whohas;
548 	struct	rman *rm;
549 
550 	r = re->__r_i;
551 	rm = r->r_rm;
552 	mtx_lock(rm->rm_mtx);
553 	for (;;) {
554 		rv = int_rman_activate_resource(rm, r, &whohas);
555 		if (rv != EBUSY)
556 			return (rv);	/* returns with mutex held */
557 
558 		if (r->r_sharehead == NULL)
559 			panic("rman_await_resource");
560 		whohas->r_flags |= RF_WANTED;
561 		rv = msleep(r->r_sharehead, rm->rm_mtx, pri, "rmwait", timo);
562 		if (rv) {
563 			mtx_unlock(rm->rm_mtx);
564 			return (rv);
565 		}
566 	}
567 }
568 
569 static int
570 int_rman_deactivate_resource(struct resource_i *r)
571 {
572 
573 	r->r_flags &= ~RF_ACTIVE;
574 	if (r->r_flags & RF_WANTED) {
575 		r->r_flags &= ~RF_WANTED;
576 		wakeup(r->r_sharehead);
577 	}
578 	return 0;
579 }
580 
581 int
582 rman_deactivate_resource(struct resource *r)
583 {
584 	struct	rman *rm;
585 
586 	rm = r->__r_i->r_rm;
587 	mtx_lock(rm->rm_mtx);
588 	int_rman_deactivate_resource(r->__r_i);
589 	mtx_unlock(rm->rm_mtx);
590 	return 0;
591 }
592 
593 static int
594 int_rman_release_resource(struct rman *rm, struct resource_i *r)
595 {
596 	struct	resource_i *s, *t;
597 
598 	if (r->r_flags & RF_ACTIVE)
599 		int_rman_deactivate_resource(r);
600 
601 	/*
602 	 * Check for a sharing list first.  If there is one, then we don't
603 	 * have to think as hard.
604 	 */
605 	if (r->r_sharehead) {
606 		/*
607 		 * If a sharing list exists, then we know there are at
608 		 * least two sharers.
609 		 *
610 		 * If we are in the main circleq, appoint someone else.
611 		 */
612 		LIST_REMOVE(r, r_sharelink);
613 		s = LIST_FIRST(r->r_sharehead);
614 		if (r->r_flags & RF_FIRSTSHARE) {
615 			s->r_flags |= RF_FIRSTSHARE;
616 			TAILQ_INSERT_BEFORE(r, s, r_link);
617 			TAILQ_REMOVE(&rm->rm_list, r, r_link);
618 		}
619 
620 		/*
621 		 * Make sure that the sharing list goes away completely
622 		 * if the resource is no longer being shared at all.
623 		 */
624 		if (LIST_NEXT(s, r_sharelink) == NULL) {
625 			free(s->r_sharehead, M_RMAN);
626 			s->r_sharehead = NULL;
627 			s->r_flags &= ~RF_FIRSTSHARE;
628 		}
629 		goto out;
630 	}
631 
632 	/*
633 	 * Look at the adjacent resources in the list and see if our
634 	 * segment can be merged with any of them.  If either of the
635 	 * resources is allocated or is not exactly adjacent then they
636 	 * cannot be merged with our segment.
637 	 */
638 	s = TAILQ_PREV(r, resource_head, r_link);
639 	if (s != NULL && ((s->r_flags & RF_ALLOCATED) != 0 ||
640 	    s->r_end + 1 != r->r_start))
641 		s = NULL;
642 	t = TAILQ_NEXT(r, r_link);
643 	if (t != NULL && ((t->r_flags & RF_ALLOCATED) != 0 ||
644 	    r->r_end + 1 != t->r_start))
645 		t = NULL;
646 
647 	if (s != NULL && t != NULL) {
648 		/*
649 		 * Merge all three segments.
650 		 */
651 		s->r_end = t->r_end;
652 		TAILQ_REMOVE(&rm->rm_list, r, r_link);
653 		TAILQ_REMOVE(&rm->rm_list, t, r_link);
654 		free(t, M_RMAN);
655 	} else if (s != NULL) {
656 		/*
657 		 * Merge previous segment with ours.
658 		 */
659 		s->r_end = r->r_end;
660 		TAILQ_REMOVE(&rm->rm_list, r, r_link);
661 	} else if (t != NULL) {
662 		/*
663 		 * Merge next segment with ours.
664 		 */
665 		t->r_start = r->r_start;
666 		TAILQ_REMOVE(&rm->rm_list, r, r_link);
667 	} else {
668 		/*
669 		 * At this point, we know there is nothing we
670 		 * can potentially merge with, because on each
671 		 * side, there is either nothing there or what is
672 		 * there is still allocated.  In that case, we don't
673 		 * want to remove r from the list; we simply want to
674 		 * change it to an unallocated region and return
675 		 * without freeing anything.
676 		 */
677 		r->r_flags &= ~RF_ALLOCATED;
678 		return 0;
679 	}
680 
681 out:
682 	free(r, M_RMAN);
683 	return 0;
684 }
685 
686 int
687 rman_release_resource(struct resource *re)
688 {
689 	int	rv;
690 	struct	resource_i *r;
691 	struct	rman *rm;
692 
693 	r = re->__r_i;
694 	rm = r->r_rm;
695 	mtx_lock(rm->rm_mtx);
696 	rv = int_rman_release_resource(rm, r);
697 	mtx_unlock(rm->rm_mtx);
698 	return (rv);
699 }
700 
701 uint32_t
702 rman_make_alignment_flags(uint32_t size)
703 {
704 	int	i;
705 
706 	/*
707 	 * Find the hightest bit set, and add one if more than one bit
708 	 * set.  We're effectively computing the ceil(log2(size)) here.
709 	 */
710 	for (i = 31; i > 0; i--)
711 		if ((1 << i) & size)
712 			break;
713 	if (~(1 << i) & size)
714 		i++;
715 
716 	return(RF_ALIGNMENT_LOG2(i));
717 }
718 
719 u_long
720 rman_get_start(struct resource *r)
721 {
722 	return (r->__r_i->r_start);
723 }
724 
725 u_long
726 rman_get_end(struct resource *r)
727 {
728 	return (r->__r_i->r_end);
729 }
730 
731 u_long
732 rman_get_size(struct resource *r)
733 {
734 	return (r->__r_i->r_end - r->__r_i->r_start + 1);
735 }
736 
737 u_int
738 rman_get_flags(struct resource *r)
739 {
740 	return (r->__r_i->r_flags);
741 }
742 
743 void
744 rman_set_virtual(struct resource *r, void *v)
745 {
746 	r->__r_i->r_virtual = v;
747 }
748 
749 void *
750 rman_get_virtual(struct resource *r)
751 {
752 	return (r->__r_i->r_virtual);
753 }
754 
755 void
756 rman_set_bustag(struct resource *r, bus_space_tag_t t)
757 {
758 	r->r_bustag = t;
759 }
760 
761 bus_space_tag_t
762 rman_get_bustag(struct resource *r)
763 {
764 	return (r->r_bustag);
765 }
766 
767 void
768 rman_set_bushandle(struct resource *r, bus_space_handle_t h)
769 {
770 	r->r_bushandle = h;
771 }
772 
773 bus_space_handle_t
774 rman_get_bushandle(struct resource *r)
775 {
776 	return (r->r_bushandle);
777 }
778 
779 void
780 rman_set_rid(struct resource *r, int rid)
781 {
782 	r->__r_i->r_rid = rid;
783 }
784 
785 void
786 rman_set_start(struct resource *r, u_long start)
787 {
788 	r->__r_i->r_start = start;
789 }
790 
791 void
792 rman_set_end(struct resource *r, u_long end)
793 {
794 	r->__r_i->r_end = end;
795 }
796 
797 int
798 rman_get_rid(struct resource *r)
799 {
800 	return (r->__r_i->r_rid);
801 }
802 
803 struct device *
804 rman_get_device(struct resource *r)
805 {
806 	return (r->__r_i->r_dev);
807 }
808 
809 void
810 rman_set_device(struct resource *r, struct device *dev)
811 {
812 	r->__r_i->r_dev = dev;
813 }
814 
815 int
816 rman_is_region_manager(struct resource *r, struct rman *rm)
817 {
818 
819 	return (r->__r_i->r_rm == rm);
820 }
821 
822 /*
823  * Sysctl interface for scanning the resource lists.
824  *
825  * We take two input parameters; the index into the list of resource
826  * managers, and the resource offset into the list.
827  */
828 static int
829 sysctl_rman(SYSCTL_HANDLER_ARGS)
830 {
831 	int			*name = (int *)arg1;
832 	u_int			namelen = arg2;
833 	int			rman_idx, res_idx;
834 	struct rman		*rm;
835 	struct resource_i	*res;
836 	struct u_rman		urm;
837 	struct u_resource	ures;
838 	int			error;
839 
840 	if (namelen != 3)
841 		return (EINVAL);
842 
843 	if (bus_data_generation_check(name[0]))
844 		return (EINVAL);
845 	rman_idx = name[1];
846 	res_idx = name[2];
847 
848 	/*
849 	 * Find the indexed resource manager
850 	 */
851 	mtx_lock(&rman_mtx);
852 	TAILQ_FOREACH(rm, &rman_head, rm_link) {
853 		if (rman_idx-- == 0)
854 			break;
855 	}
856 	mtx_unlock(&rman_mtx);
857 	if (rm == NULL)
858 		return (ENOENT);
859 
860 	/*
861 	 * If the resource index is -1, we want details on the
862 	 * resource manager.
863 	 */
864 	if (res_idx == -1) {
865 		bzero(&urm, sizeof(urm));
866 		urm.rm_handle = (uintptr_t)rm;
867 		strlcpy(urm.rm_descr, rm->rm_descr, RM_TEXTLEN);
868 		urm.rm_start = rm->rm_start;
869 		urm.rm_size = rm->rm_end - rm->rm_start + 1;
870 		urm.rm_type = rm->rm_type;
871 
872 		error = SYSCTL_OUT(req, &urm, sizeof(urm));
873 		return (error);
874 	}
875 
876 	/*
877 	 * Find the indexed resource and return it.
878 	 */
879 	mtx_lock(rm->rm_mtx);
880 	TAILQ_FOREACH(res, &rm->rm_list, r_link) {
881 		if (res_idx-- == 0) {
882 			bzero(&ures, sizeof(ures));
883 			ures.r_handle = (uintptr_t)res;
884 			ures.r_parent = (uintptr_t)res->r_rm;
885 			ures.r_device = (uintptr_t)res->r_dev;
886 			if (res->r_dev != NULL) {
887 				if (device_get_name(res->r_dev) != NULL) {
888 					snprintf(ures.r_devname, RM_TEXTLEN,
889 					    "%s%d",
890 					    device_get_name(res->r_dev),
891 					    device_get_unit(res->r_dev));
892 				} else {
893 					strlcpy(ures.r_devname, "nomatch",
894 					    RM_TEXTLEN);
895 				}
896 			} else {
897 				ures.r_devname[0] = '\0';
898 			}
899 			ures.r_start = res->r_start;
900 			ures.r_size = res->r_end - res->r_start + 1;
901 			ures.r_flags = res->r_flags;
902 
903 			mtx_unlock(rm->rm_mtx);
904 			error = SYSCTL_OUT(req, &ures, sizeof(ures));
905 			return (error);
906 		}
907 	}
908 	mtx_unlock(rm->rm_mtx);
909 	return (ENOENT);
910 }
911 
912 SYSCTL_NODE(_hw_bus, OID_AUTO, rman, CTLFLAG_RD, sysctl_rman,
913     "kernel resource manager");
914