2 * Copyright 1998 Massachusetts Institute of Technology
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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 1.5 2003/11/15 21:05:43 dillon Exp $
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
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
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
61 #include <sys/param.h>
62 #include <sys/systm.h>
63 #include <sys/kernel.h>
65 #include <sys/malloc.h>
66 #include <sys/bus.h> /* XXX debugging */
67 #include <machine/bus.h>
70 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
72 struct rman_head rman_head;
73 static struct lwkt_token rman_tok; /* mutex to protect rman_head */
74 static int int_rman_activate_resource(struct rman *rm, struct resource *r,
75 struct resource **whohas);
76 static int int_rman_deactivate_resource(struct resource *r);
77 static int int_rman_release_resource(struct rman *rm, struct resource *r);
79 #define CIRCLEQ_TERMCOND(var, head) (var == (void *)&(head))
82 rman_init(struct rman *rm)
88 TAILQ_INIT(&rman_head);
89 lwkt_inittoken(&rman_tok);
92 if (rm->rm_type == RMAN_UNINIT)
94 if (rm->rm_type == RMAN_GAUGE)
95 panic("implement RMAN_GAUGE");
97 CIRCLEQ_INIT(&rm->rm_list);
98 rm->rm_slock = malloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
99 if (rm->rm_slock == NULL)
101 lwkt_inittoken(rm->rm_slock);
103 lwkt_gettoken(&rman_tok);
104 TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
105 lwkt_reltoken(&rman_tok);
110 * NB: this interface is not robust against programming errors which
111 * add multiple copies of the same region.
114 rman_manage_region(struct rman *rm, u_long start, u_long end)
116 struct resource *r, *s;
118 r = malloc(sizeof *r, M_RMAN, M_NOWAIT);
129 lwkt_gettoken(rm->rm_slock);
130 for (s = CIRCLEQ_FIRST(&rm->rm_list);
131 !CIRCLEQ_TERMCOND(s, rm->rm_list) && s->r_end < r->r_start;
132 s = CIRCLEQ_NEXT(s, r_link))
135 if (CIRCLEQ_TERMCOND(s, rm->rm_list)) {
136 CIRCLEQ_INSERT_TAIL(&rm->rm_list, r, r_link);
138 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, r, r_link);
141 lwkt_reltoken(rm->rm_slock);
146 rman_fini(struct rman *rm)
150 lwkt_gettoken(rm->rm_slock);
151 CIRCLEQ_FOREACH(r, &rm->rm_list, r_link) {
152 if (r->r_flags & RF_ALLOCATED) {
153 lwkt_reltoken(rm->rm_slock);
159 * There really should only be one of these if we are in this
160 * state and the code is working properly, but it can't hurt.
162 while (!CIRCLEQ_EMPTY(&rm->rm_list)) {
163 r = CIRCLEQ_FIRST(&rm->rm_list);
164 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
167 lwkt_reltoken(rm->rm_slock);
168 lwkt_gettoken(&rman_tok);
169 TAILQ_REMOVE(&rman_head, rm, rm_link);
170 lwkt_reltoken(&rman_tok);
171 free(rm->rm_slock, M_RMAN);
177 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
178 u_int flags, struct device *dev)
181 struct resource *r, *s, *rv;
187 printf("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
188 "%#lx, flags %u, device %s%d\n", rm->rm_descr, start, end,
189 count, flags, device_get_name(dev), device_get_unit(dev));
190 #endif /* RMAN_DEBUG */
191 want_activate = (flags & RF_ACTIVE);
194 lwkt_gettoken(rm->rm_slock);
196 for (r = CIRCLEQ_FIRST(&rm->rm_list);
197 !CIRCLEQ_TERMCOND(r, rm->rm_list) && r->r_end < start;
198 r = CIRCLEQ_NEXT(r, r_link))
201 if (CIRCLEQ_TERMCOND(r, rm->rm_list)) {
203 printf("could not find a region\n");
209 * First try to find an acceptable totally-unshared region.
211 for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
212 s = CIRCLEQ_NEXT(s, r_link)) {
214 printf("considering [%#lx, %#lx]\n", s->r_start, s->r_end);
215 #endif /* RMAN_DEBUG */
216 if (s->r_start > end) {
218 printf("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end);
219 #endif /* RMAN_DEBUG */
222 if (s->r_flags & RF_ALLOCATED) {
224 printf("region is allocated\n");
225 #endif /* RMAN_DEBUG */
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));
233 printf("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
234 rstart, rend, (rend - rstart + 1), count);
235 #endif /* RMAN_DEBUG */
237 if ((rend - rstart + 1) >= count) {
239 printf("candidate region: [%#lx, %#lx], size %#lx\n",
240 rend, rstart, (rend - rstart + 1));
241 #endif /* RMAN_DEBUG */
242 if ((s->r_end - s->r_start + 1) == count) {
244 printf("candidate region is entire chunk\n");
245 #endif /* RMAN_DEBUG */
247 rv->r_flags |= RF_ALLOCATED | flags;
253 * If s->r_start < rstart and
254 * s->r_end > rstart + count - 1, then
255 * we need to split the region into three pieces
256 * (the middle one will get returned to the user).
257 * Otherwise, we are allocating at either the
258 * beginning or the end of s, so we only need to
259 * split it in two. The first case requires
260 * two new allocations; the second requires but one.
262 rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT);
265 bzero(rv, sizeof *rv);
266 rv->r_start = rstart;
267 rv->r_end = rstart + count - 1;
268 rv->r_flags = flags | RF_ALLOCATED;
273 if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
275 printf("splitting region in three parts: "
276 "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
277 s->r_start, rv->r_start - 1,
278 rv->r_start, rv->r_end,
279 rv->r_end + 1, s->r_end);
280 #endif /* RMAN_DEBUG */
282 * We are allocating in the middle.
284 r = malloc(sizeof *r, M_RMAN, M_NOWAIT);
291 r->r_start = rv->r_end + 1;
293 r->r_flags = s->r_flags;
297 s->r_end = rv->r_start - 1;
298 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
300 CIRCLEQ_INSERT_AFTER(&rm->rm_list, rv, r,
302 } else if (s->r_start == rv->r_start) {
304 printf("allocating from the beginning\n");
305 #endif /* RMAN_DEBUG */
307 * We are allocating at the beginning.
309 s->r_start = rv->r_end + 1;
310 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, rv,
314 printf("allocating at the end\n");
315 #endif /* RMAN_DEBUG */
317 * We are allocating at the end.
319 s->r_end = rv->r_start - 1;
320 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv,
328 * Now find an acceptable shared region, if the client's requirements
329 * allow sharing. By our implementation restriction, a candidate
330 * region must match exactly by both size and sharing type in order
331 * to be considered compatible with the client's request. (The
332 * former restriction could probably be lifted without too much
333 * additional work, but this does not seem warranted.)
336 printf("no unshared regions found\n");
337 #endif /* RMAN_DEBUG */
338 if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
341 for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list);
342 s = CIRCLEQ_NEXT(s, r_link)) {
343 if (s->r_start > end)
345 if ((s->r_flags & flags) != flags)
347 rstart = max(s->r_start, start);
348 rend = min(s->r_end, max(start + count, end));
349 if (s->r_start >= start && s->r_end <= end
350 && (s->r_end - s->r_start + 1) == count) {
351 rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT);
354 bzero(rv, sizeof *rv);
355 rv->r_start = s->r_start;
356 rv->r_end = s->r_end;
357 rv->r_flags = s->r_flags &
358 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
361 if (s->r_sharehead == 0) {
362 s->r_sharehead = malloc(sizeof *s->r_sharehead,
364 if (s->r_sharehead == 0) {
369 bzero(s->r_sharehead, sizeof *s->r_sharehead);
370 LIST_INIT(s->r_sharehead);
371 LIST_INSERT_HEAD(s->r_sharehead, s,
373 s->r_flags |= RF_FIRSTSHARE;
375 rv->r_sharehead = s->r_sharehead;
376 LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
382 * We couldn't find anything.
386 * If the user specified RF_ACTIVE in the initial flags,
387 * which is reflected in `want_activate', we attempt to atomically
388 * activate the resource. If this fails, we release the resource
389 * and indicate overall failure. (This behavior probably doesn't
390 * make sense for RF_TIMESHARE-type resources.)
392 if (rv && want_activate) {
393 struct resource *whohas;
394 if (int_rman_activate_resource(rm, rv, &whohas)) {
395 int_rman_release_resource(rm, rv);
400 lwkt_reltoken(rm->rm_slock);
405 int_rman_activate_resource(struct rman *rm, struct resource *r,
406 struct resource **whohas)
412 * If we are not timesharing, then there is nothing much to do.
413 * If we already have the resource, then there is nothing at all to do.
414 * If we are not on a sharing list with anybody else, then there is
417 if ((r->r_flags & RF_TIMESHARE) == 0
418 || (r->r_flags & RF_ACTIVE) != 0
419 || r->r_sharehead == 0) {
420 r->r_flags |= RF_ACTIVE;
425 for (s = LIST_FIRST(r->r_sharehead); s && ok;
426 s = LIST_NEXT(s, r_sharelink)) {
427 if ((s->r_flags & RF_ACTIVE) != 0) {
433 r->r_flags |= RF_ACTIVE;
440 rman_activate_resource(struct resource *r)
443 struct resource *whohas;
447 lwkt_gettoken(rm->rm_slock);
448 rv = int_rman_activate_resource(rm, r, &whohas);
449 lwkt_reltoken(rm->rm_slock);
454 rman_await_resource(struct resource *r, int slpflags, int timo)
457 struct resource *whohas;
462 lwkt_gettoken(rm->rm_slock);
463 rv = int_rman_activate_resource(rm, r, &whohas);
465 return (rv); /* returns with simple token */
467 if (r->r_sharehead == 0)
468 panic("rman_await_resource");
470 * splhigh hopefully will prevent a race between
471 * lwkt_reltoken and tsleep where a process
472 * could conceivably get in and release the resource
473 * before we have a chance to sleep on it. YYY
476 whohas->r_flags |= RF_WANTED;
477 lwkt_reltoken(rm->rm_slock); /* YYY */
478 rv = tsleep(r->r_sharehead, slpflags, "rmwait", timo);
483 lwkt_gettoken(rm->rm_slock);
489 int_rman_deactivate_resource(struct resource *r)
494 r->r_flags &= ~RF_ACTIVE;
495 if (r->r_flags & RF_WANTED) {
496 r->r_flags &= ~RF_WANTED;
497 wakeup(r->r_sharehead);
503 rman_deactivate_resource(struct resource *r)
508 lwkt_gettoken(rm->rm_slock);
509 int_rman_deactivate_resource(r);
510 lwkt_reltoken(rm->rm_slock);
515 int_rman_release_resource(struct rman *rm, struct resource *r)
517 struct resource *s, *t;
519 if (r->r_flags & RF_ACTIVE)
520 int_rman_deactivate_resource(r);
523 * Check for a sharing list first. If there is one, then we don't
524 * have to think as hard.
526 if (r->r_sharehead) {
528 * If a sharing list exists, then we know there are at
531 * If we are in the main circleq, appoint someone else.
533 LIST_REMOVE(r, r_sharelink);
534 s = LIST_FIRST(r->r_sharehead);
535 if (r->r_flags & RF_FIRSTSHARE) {
536 s->r_flags |= RF_FIRSTSHARE;
537 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, r, s, r_link);
538 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
542 * Make sure that the sharing list goes away completely
543 * if the resource is no longer being shared at all.
545 if (LIST_NEXT(s, r_sharelink) == 0) {
546 free(s->r_sharehead, M_RMAN);
548 s->r_flags &= ~RF_FIRSTSHARE;
554 * Look at the adjacent resources in the list and see if our
555 * segment can be merged with any of them.
557 s = CIRCLEQ_PREV(r, r_link);
558 t = CIRCLEQ_NEXT(r, r_link);
560 if (s != (void *)&rm->rm_list && (s->r_flags & RF_ALLOCATED) == 0
561 && t != (void *)&rm->rm_list && (t->r_flags & RF_ALLOCATED) == 0) {
563 * Merge all three segments.
566 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
567 CIRCLEQ_REMOVE(&rm->rm_list, t, r_link);
569 } else if (s != (void *)&rm->rm_list
570 && (s->r_flags & RF_ALLOCATED) == 0) {
572 * Merge previous segment with ours.
575 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
576 } else if (t != (void *)&rm->rm_list
577 && (t->r_flags & RF_ALLOCATED) == 0) {
579 * Merge next segment with ours.
581 t->r_start = r->r_start;
582 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link);
585 * At this point, we know there is nothing we
586 * can potentially merge with, because on each
587 * side, there is either nothing there or what is
588 * there is still allocated. In that case, we don't
589 * want to remove r from the list; we simply want to
590 * change it to an unallocated region and return
591 * without freeing anything.
593 r->r_flags &= ~RF_ALLOCATED;
603 rman_release_resource(struct resource *r)
606 struct rman *rm = r->r_rm;
608 lwkt_gettoken(rm->rm_slock);
609 rv = int_rman_release_resource(rm, r);
610 lwkt_reltoken(rm->rm_slock);
615 rman_make_alignment_flags(uint32_t size)
620 * Find the hightest bit set, and add one if more than one bit
621 * set. We're effectively computing the ceil(log2(size)) here.
623 for (i = 32; i > 0; i--)
626 if (~(1 << i) & size)
629 return(RF_ALIGNMENT_LOG2(i));