2 * Copyright 1998 Massachusetts Institute of Technology
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
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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
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24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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26 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * The kernel resource manager. This code is responsible for keeping track
34 * of hardware resources which are apportioned out to various drivers.
35 * It does not actually assign those resources, and it is not expected
36 * that end-device drivers will call into this code directly. Rather,
37 * the code which implements the buses that those devices are attached to,
38 * and the code which manages CPU resources, will call this code, and the
39 * end-device drivers will make upcalls to that code to actually perform
42 * There are two sorts of resources managed by this code. The first is
43 * the more familiar array (RMAN_ARRAY) type; resources in this class
44 * consist of a sequence of individually-allocatable objects which have
45 * been numbered in some well-defined order. Most of the resources
46 * are of this type, as it is the most familiar. The second type is
47 * called a gauge (RMAN_GAUGE), and models fungible resources (i.e.,
48 * resources in which each instance is indistinguishable from every
49 * other instance). The principal anticipated application of gauges
50 * is in the context of power consumption, where a bus may have a specific
51 * power budget which all attached devices share. RMAN_GAUGE is not
54 * For array resources, we make one simplifying assumption: two clients
55 * sharing the same resource must use the same range of indices. That
56 * is to say, sharing of overlapping-but-not-identical regions is not
60 #include <sys/param.h>
61 #include <sys/systm.h>
62 #include <sys/kernel.h>
64 #include <sys/malloc.h>
65 #include <sys/mutex.h>
66 #include <sys/bus.h> /* XXX debugging */
67 #include <machine/bus.h>
71 #define DPRINTF(params) printf##params
73 #define DPRINTF(params)
76 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
78 struct rman_head rman_head;
79 static struct mtx rman_mtx; /* mutex to protect rman_head */
80 static int int_rman_activate_resource(struct rman *rm, struct resource *r,
81 struct resource **whohas);
82 static int int_rman_deactivate_resource(struct resource *r);
83 static int int_rman_release_resource(struct rman *rm, struct resource *r);
86 rman_init(struct rman *rm)
92 TAILQ_INIT(&rman_head);
93 mtx_init(&rman_mtx, "rman head", MTX_DEF);
96 if (rm->rm_type == RMAN_UNINIT)
98 if (rm->rm_type == RMAN_GAUGE)
99 panic("implement RMAN_GAUGE");
101 TAILQ_INIT(&rm->rm_list);
102 rm->rm_mtx = malloc(sizeof *rm->rm_mtx, M_RMAN, M_NOWAIT | M_ZERO);
105 mtx_init(rm->rm_mtx, "rman", MTX_DEF);
108 TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
109 mtx_unlock(&rman_mtx);
114 * NB: this interface is not robust against programming errors which
115 * add multiple copies of the same region.
118 rman_manage_region(struct rman *rm, u_long start, u_long end)
120 struct resource *r, *s;
122 r = malloc(sizeof *r, M_RMAN, M_NOWAIT | M_ZERO);
129 mtx_lock(rm->rm_mtx);
130 for (s = TAILQ_FIRST(&rm->rm_list);
131 s && s->r_end < r->r_start;
132 s = TAILQ_NEXT(s, r_link))
136 TAILQ_INSERT_TAIL(&rm->rm_list, r, r_link);
138 TAILQ_INSERT_BEFORE(s, r, r_link);
141 mtx_unlock(rm->rm_mtx);
146 rman_fini(struct rman *rm)
150 mtx_lock(rm->rm_mtx);
151 TAILQ_FOREACH(r, &rm->rm_list, r_link) {
152 if (r->r_flags & RF_ALLOCATED) {
153 mtx_unlock(rm->rm_mtx);
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 (!TAILQ_EMPTY(&rm->rm_list)) {
163 r = TAILQ_FIRST(&rm->rm_list);
164 TAILQ_REMOVE(&rm->rm_list, r, r_link);
167 mtx_unlock(rm->rm_mtx);
169 TAILQ_REMOVE(&rman_head, rm, rm_link);
170 mtx_unlock(&rman_mtx);
171 mtx_destroy(rm->rm_mtx);
172 free(rm->rm_mtx, M_RMAN);
178 rman_reserve_resource_bound(struct rman *rm, u_long start, u_long end,
179 u_long count, u_long bound, u_int flags,
183 struct resource *r, *s, *rv;
184 u_long rstart, rend, amask, bmask;
188 DPRINTF(("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
189 "%#lx, flags %u, device %s\n", rm->rm_descr, start, end, count,
190 flags, dev == NULL ? "<null>" : device_get_nameunit(dev)));
191 want_activate = (flags & RF_ACTIVE);
194 mtx_lock(rm->rm_mtx);
196 for (r = TAILQ_FIRST(&rm->rm_list);
197 r && r->r_end < start;
198 r = TAILQ_NEXT(r, r_link))
202 DPRINTF(("could not find a region\n"));
206 amask = (1ul << RF_ALIGNMENT(flags)) - 1;
207 /* If bound is 0, bmask will also be 0 */
208 bmask = ~(bound - 1);
210 * First try to find an acceptable totally-unshared region.
212 for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
213 DPRINTF(("considering [%#lx, %#lx]\n", s->r_start, s->r_end));
214 if (s->r_start > end) {
215 DPRINTF(("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end));
218 if (s->r_flags & RF_ALLOCATED) {
219 DPRINTF(("region is allocated\n"));
222 rstart = ulmax(s->r_start, start);
224 * Try to find a region by adjusting to boundary and alignment
225 * until both conditions are satisfied. This is not an optimal
226 * algorithm, but in most cases it isn't really bad, either.
229 rstart = (rstart + amask) & ~amask;
230 if (((rstart ^ (rstart + count)) & bmask) != 0)
231 rstart += bound - (rstart & ~bmask);
232 } while ((rstart & amask) != 0 && rstart < end &&
234 rend = ulmin(s->r_end, ulmax(rstart + count, end));
235 DPRINTF(("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
236 rstart, rend, (rend - rstart + 1), count));
238 if ((rend - rstart + 1) >= count) {
239 DPRINTF(("candidate region: [%#lx, %#lx], size %#lx\n",
240 rend, rstart, (rend - rstart + 1)));
241 if ((s->r_end - s->r_start + 1) == count) {
242 DPRINTF(("candidate region is entire chunk\n"));
244 rv->r_flags |= RF_ALLOCATED | flags;
250 * If s->r_start < rstart and
251 * s->r_end > rstart + count - 1, then
252 * we need to split the region into three pieces
253 * (the middle one will get returned to the user).
254 * Otherwise, we are allocating at either the
255 * beginning or the end of s, so we only need to
256 * split it in two. The first case requires
257 * two new allocations; the second requires but one.
259 rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO);
262 rv->r_start = rstart;
263 rv->r_end = rstart + count - 1;
264 rv->r_flags = flags | RF_ALLOCATED;
268 if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
269 DPRINTF(("splitting region in three parts: "
270 "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
271 s->r_start, rv->r_start - 1,
272 rv->r_start, rv->r_end,
273 rv->r_end + 1, s->r_end));
275 * We are allocating in the middle.
277 r = malloc(sizeof *r, M_RMAN, M_NOWAIT|M_ZERO);
283 r->r_start = rv->r_end + 1;
285 r->r_flags = s->r_flags;
287 s->r_end = rv->r_start - 1;
288 TAILQ_INSERT_AFTER(&rm->rm_list, s, rv,
290 TAILQ_INSERT_AFTER(&rm->rm_list, rv, r,
292 } else if (s->r_start == rv->r_start) {
293 DPRINTF(("allocating from the beginning\n"));
295 * We are allocating at the beginning.
297 s->r_start = rv->r_end + 1;
298 TAILQ_INSERT_BEFORE(s, rv, r_link);
300 DPRINTF(("allocating at the end\n"));
302 * We are allocating at the end.
304 s->r_end = rv->r_start - 1;
305 TAILQ_INSERT_AFTER(&rm->rm_list, s, rv,
313 * Now find an acceptable shared region, if the client's requirements
314 * allow sharing. By our implementation restriction, a candidate
315 * region must match exactly by both size and sharing type in order
316 * to be considered compatible with the client's request. (The
317 * former restriction could probably be lifted without too much
318 * additional work, but this does not seem warranted.)
320 DPRINTF(("no unshared regions found\n"));
321 if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
324 for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
325 if (s->r_start > end)
327 if ((s->r_flags & flags) != flags)
329 rstart = ulmax(s->r_start, start);
330 rend = ulmin(s->r_end, ulmax(start + count, end));
331 if (s->r_start >= start && s->r_end <= end
332 && (s->r_end - s->r_start + 1) == count &&
333 (s->r_start & amask) == 0 &&
334 ((s->r_start ^ s->r_end) & bmask) == 0) {
335 rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO);
338 rv->r_start = s->r_start;
339 rv->r_end = s->r_end;
340 rv->r_flags = s->r_flags &
341 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
344 if (s->r_sharehead == 0) {
345 s->r_sharehead = malloc(sizeof *s->r_sharehead,
346 M_RMAN, M_NOWAIT | M_ZERO);
347 if (s->r_sharehead == 0) {
352 LIST_INIT(s->r_sharehead);
353 LIST_INSERT_HEAD(s->r_sharehead, s,
355 s->r_flags |= RF_FIRSTSHARE;
357 rv->r_sharehead = s->r_sharehead;
358 LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
364 * We couldn't find anything.
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.)
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);
382 mtx_unlock(rm->rm_mtx);
387 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
388 u_int flags, struct device *dev)
391 return (rman_reserve_resource_bound(rm, start, end, count, 0, flags,
396 int_rman_activate_resource(struct rman *rm, struct resource *r,
397 struct resource **whohas)
403 * If we are not timesharing, then there is nothing much to do.
404 * If we already have the resource, then there is nothing at all to do.
405 * If we are not on a sharing list with anybody else, then there is
408 if ((r->r_flags & RF_TIMESHARE) == 0
409 || (r->r_flags & RF_ACTIVE) != 0
410 || r->r_sharehead == 0) {
411 r->r_flags |= RF_ACTIVE;
416 for (s = LIST_FIRST(r->r_sharehead); s && ok;
417 s = LIST_NEXT(s, r_sharelink)) {
418 if ((s->r_flags & RF_ACTIVE) != 0) {
424 r->r_flags |= RF_ACTIVE;
431 rman_activate_resource(struct resource *r)
434 struct resource *whohas;
438 mtx_lock(rm->rm_mtx);
439 rv = int_rman_activate_resource(rm, r, &whohas);
440 mtx_unlock(rm->rm_mtx);
445 rman_await_resource(struct resource *r, int pri, int timo)
448 struct resource *whohas;
452 mtx_lock(rm->rm_mtx);
454 rv = int_rman_activate_resource(rm, r, &whohas);
456 return (rv); /* returns with mutex held */
458 if (r->r_sharehead == 0)
459 panic("rman_await_resource");
460 whohas->r_flags |= RF_WANTED;
461 rv = msleep(r->r_sharehead, rm->rm_mtx, pri, "rmwait", timo);
463 mtx_unlock(rm->rm_mtx);
470 int_rman_deactivate_resource(struct resource *r)
475 r->r_flags &= ~RF_ACTIVE;
476 if (r->r_flags & RF_WANTED) {
477 r->r_flags &= ~RF_WANTED;
478 wakeup(r->r_sharehead);
484 rman_deactivate_resource(struct resource *r)
489 mtx_lock(rm->rm_mtx);
490 int_rman_deactivate_resource(r);
491 mtx_unlock(rm->rm_mtx);
496 int_rman_release_resource(struct rman *rm, struct resource *r)
498 struct resource *s, *t;
500 if (r->r_flags & RF_ACTIVE)
501 int_rman_deactivate_resource(r);
504 * Check for a sharing list first. If there is one, then we don't
505 * have to think as hard.
507 if (r->r_sharehead) {
509 * If a sharing list exists, then we know there are at
512 * If we are in the main circleq, appoint someone else.
514 LIST_REMOVE(r, r_sharelink);
515 s = LIST_FIRST(r->r_sharehead);
516 if (r->r_flags & RF_FIRSTSHARE) {
517 s->r_flags |= RF_FIRSTSHARE;
518 TAILQ_INSERT_BEFORE(r, s, r_link);
519 TAILQ_REMOVE(&rm->rm_list, r, r_link);
523 * Make sure that the sharing list goes away completely
524 * if the resource is no longer being shared at all.
526 if (LIST_NEXT(s, r_sharelink) == 0) {
527 free(s->r_sharehead, M_RMAN);
529 s->r_flags &= ~RF_FIRSTSHARE;
535 * Look at the adjacent resources in the list and see if our
536 * segment can be merged with any of them.
538 s = TAILQ_PREV(r, resource_head, r_link);
539 t = TAILQ_NEXT(r, r_link);
541 if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0
542 && t != NULL && (t->r_flags & RF_ALLOCATED) == 0) {
544 * Merge all three segments.
547 TAILQ_REMOVE(&rm->rm_list, r, r_link);
548 TAILQ_REMOVE(&rm->rm_list, t, r_link);
550 } else if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0) {
552 * Merge previous segment with ours.
555 TAILQ_REMOVE(&rm->rm_list, r, r_link);
556 } else if (t != NULL && (t->r_flags & RF_ALLOCATED) == 0) {
558 * Merge next segment with ours.
560 t->r_start = r->r_start;
561 TAILQ_REMOVE(&rm->rm_list, r, r_link);
564 * At this point, we know there is nothing we
565 * can potentially merge with, because on each
566 * side, there is either nothing there or what is
567 * there is still allocated. In that case, we don't
568 * want to remove r from the list; we simply want to
569 * change it to an unallocated region and return
570 * without freeing anything.
572 r->r_flags &= ~RF_ALLOCATED;
582 rman_release_resource(struct resource *r)
585 struct rman *rm = r->r_rm;
587 mtx_lock(rm->rm_mtx);
588 rv = int_rman_release_resource(rm, r);
589 mtx_unlock(rm->rm_mtx);
594 rman_make_alignment_flags(uint32_t size)
599 * Find the hightest bit set, and add one if more than one bit
600 * set. We're effectively computing the ceil(log2(size)) here.
602 for (i = 31; i > 0; i--)
605 if (~(1 << i) & size)
608 return(RF_ALIGNMENT_LOG2(i));