2 * Copyright 1998 Massachusetts Institute of Technology
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5 * its documentation for any purpose and without fee is hereby
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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 $
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/bus.h> /* XXX debugging */
67 #include <sys/sysctl.h>
70 TUNABLE_INT("debug.rman_debug", &rman_debug);
71 SYSCTL_INT(_debug, OID_AUTO, rman_debug, CTLFLAG_RW,
72 &rman_debug, 0, "rman debug");
74 #define DPRINTF(params) if (rman_debug) kprintf params
76 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
78 struct rman_head rman_head;
79 static struct lwkt_token rman_tok; /* 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, int cpuid)
92 TAILQ_INIT(&rman_head);
93 lwkt_token_init(&rman_tok, "rman");
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_slock = kmalloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT);
103 if (rm->rm_slock == NULL)
105 lwkt_token_init(rm->rm_slock, "rmanslock");
107 rm->rm_cpuid = cpuid;
109 lwkt_gettoken(&rman_tok);
110 TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
111 lwkt_reltoken(&rman_tok);
116 * NB: this interface is not robust against programming errors which
117 * add multiple copies of the same region.
120 rman_manage_region(struct rman *rm, u_long start, u_long end)
122 struct resource *r, *s;
124 DPRINTF(("rman_manage_region: <%s> request: start %#lx, end %#lx\n",
125 rm->rm_descr, start, end));
126 r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT | M_ZERO);
136 lwkt_gettoken(rm->rm_slock);
137 for (s = TAILQ_FIRST(&rm->rm_list);
138 s && s->r_end < r->r_start;
139 s = TAILQ_NEXT(s, r_link))
143 TAILQ_INSERT_TAIL(&rm->rm_list, r, r_link);
145 TAILQ_INSERT_BEFORE(s, r, r_link);
147 lwkt_reltoken(rm->rm_slock);
152 rman_fini(struct rman *rm)
156 lwkt_gettoken(rm->rm_slock);
157 TAILQ_FOREACH(r, &rm->rm_list, r_link) {
158 if (r->r_flags & RF_ALLOCATED) {
159 lwkt_reltoken(rm->rm_slock);
165 * There really should only be one of these if we are in this
166 * state and the code is working properly, but it can't hurt.
168 while (!TAILQ_EMPTY(&rm->rm_list)) {
169 r = TAILQ_FIRST(&rm->rm_list);
170 TAILQ_REMOVE(&rm->rm_list, r, r_link);
173 lwkt_reltoken(rm->rm_slock);
175 /* XXX what's the point of this if we are going to free the struct? */
176 lwkt_gettoken(&rman_tok);
177 TAILQ_REMOVE(&rman_head, rm, rm_link);
178 lwkt_reltoken(&rman_tok);
179 kfree(rm->rm_slock, M_RMAN);
185 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
186 u_int flags, struct device *dev)
189 struct resource *r, *s, *rv;
194 DPRINTF(("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
195 "%#lx, flags %u, device %s\n", rm->rm_descr, start, end,
197 dev == NULL ? "<null>" : device_get_nameunit(dev)));
198 want_activate = (flags & RF_ACTIVE);
201 lwkt_gettoken(rm->rm_slock);
203 for (r = TAILQ_FIRST(&rm->rm_list);
204 r && r->r_end < start;
205 r = TAILQ_NEXT(r, r_link))
209 DPRINTF(("could not find a region\n"));
214 * First try to find an acceptable totally-unshared region.
216 for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
217 DPRINTF(("considering [%#lx, %#lx]\n", s->r_start, s->r_end));
218 if (s->r_start > end) {
219 DPRINTF(("s->r_start (%#lx) > end (%#lx)\n",
223 if (s->r_flags & RF_ALLOCATED) {
224 DPRINTF(("region is allocated\n"));
227 rstart = max(s->r_start, start);
228 rstart = (rstart + ((1ul << RF_ALIGNMENT(flags))) - 1) &
229 ~((1ul << RF_ALIGNMENT(flags)) - 1);
230 rend = min(s->r_end, max(start + count, end));
231 DPRINTF(("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
232 rstart, rend, (rend - rstart + 1), count));
234 if ((rend - rstart + 1) >= count) {
235 DPRINTF(("candidate region: [%#lx, %#lx], size %#lx\n",
236 rstart, rend, (rend - rstart + 1)));
237 if ((s->r_end - s->r_start + 1) == count) {
238 DPRINTF(("candidate region is entire chunk\n"));
240 rv->r_flags |= RF_ALLOCATED | flags;
246 * If s->r_start < rstart and
247 * s->r_end > rstart + count - 1, then
248 * we need to split the region into three pieces
249 * (the middle one will get returned to the user).
250 * Otherwise, we are allocating at either the
251 * beginning or the end of s, so we only need to
252 * split it in two. The first case requires
253 * two new allocations; the second requires but one.
255 rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO);
258 rv->r_start = rstart;
259 rv->r_end = rstart + count - 1;
260 rv->r_flags = flags | RF_ALLOCATED;
265 if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
266 DPRINTF(("splitting region in three parts: "
267 "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
268 s->r_start, rv->r_start - 1,
269 rv->r_start, rv->r_end,
270 rv->r_end + 1, s->r_end));
272 * We are allocating in the middle.
274 r = kmalloc(sizeof *r, M_RMAN,
281 r->r_start = rv->r_end + 1;
283 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 = max(s->r_start, start);
330 rend = min(s->r_end, max(start + count, end));
331 if (s->r_start >= start && s->r_end <= end
332 && (s->r_end - s->r_start + 1) == count) {
333 rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO);
336 rv->r_start = s->r_start;
337 rv->r_end = s->r_end;
338 rv->r_flags = s->r_flags &
339 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
342 if (s->r_sharehead == 0) {
343 s->r_sharehead = kmalloc(sizeof *s->r_sharehead,
346 if (s->r_sharehead == 0) {
351 LIST_INIT(s->r_sharehead);
352 LIST_INSERT_HEAD(s->r_sharehead, s,
354 s->r_flags |= RF_FIRSTSHARE;
356 rv->r_sharehead = s->r_sharehead;
357 LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
363 * We couldn't find anything.
367 * If the user specified RF_ACTIVE in the initial flags,
368 * which is reflected in `want_activate', we attempt to atomically
369 * activate the resource. If this fails, we release the resource
370 * and indicate overall failure. (This behavior probably doesn't
371 * make sense for RF_TIMESHARE-type resources.)
373 if (rv && want_activate) {
374 struct resource *whohas;
375 if (int_rman_activate_resource(rm, rv, &whohas)) {
376 int_rman_release_resource(rm, rv);
380 lwkt_reltoken(rm->rm_slock);
385 int_rman_activate_resource(struct rman *rm, struct resource *r,
386 struct resource **whohas)
392 * If we are not timesharing, then there is nothing much to do.
393 * If we already have the resource, then there is nothing at all to do.
394 * If we are not on a sharing list with anybody else, then there is
397 if ((r->r_flags & RF_TIMESHARE) == 0
398 || (r->r_flags & RF_ACTIVE) != 0
399 || r->r_sharehead == 0) {
400 r->r_flags |= RF_ACTIVE;
405 for (s = LIST_FIRST(r->r_sharehead); s && ok;
406 s = LIST_NEXT(s, r_sharelink)) {
407 if ((s->r_flags & RF_ACTIVE) != 0) {
413 r->r_flags |= RF_ACTIVE;
420 rman_activate_resource(struct resource *r)
423 struct resource *whohas;
427 lwkt_gettoken(rm->rm_slock);
428 rv = int_rman_activate_resource(rm, r, &whohas);
429 lwkt_reltoken(rm->rm_slock);
437 rman_await_resource(struct resource *r, int slpflags, int timo)
440 struct resource *whohas;
445 lwkt_gettoken(rm->rm_slock);
446 rv = int_rman_activate_resource(rm, r, &whohas);
448 return (rv); /* returns with ilock held */
450 if (r->r_sharehead == 0)
451 panic("rman_await_resource");
453 * A critical section will hopefully will prevent a race
454 * between lwkt_reltoken and tsleep where a process
455 * could conceivably get in and release the resource
456 * before we have a chance to sleep on it. YYY
459 whohas->r_flags |= RF_WANTED;
460 rv = tsleep(r->r_sharehead, slpflags, "rmwait", timo);
462 lwkt_reltoken(rm->rm_slock);
473 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 lwkt_gettoken(rm->rm_slock);
490 int_rman_deactivate_resource(r);
491 lwkt_reltoken(rm->rm_slock);
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 kfree(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)
584 struct rman *rm = r->r_rm;
587 lwkt_gettoken(rm->rm_slock);
588 rv = int_rman_release_resource(rm, r);
589 lwkt_reltoken(rm->rm_slock);
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 = 32; i > 0; i--)
605 if (~(1 << i) & size)
608 return(RF_ALIGNMENT_LOG2(i));
612 * Sysctl interface for scanning the resource lists.
614 * We take two input parameters; the index into the list of resource
615 * managers, and the resource offset into the list.
618 sysctl_rman(SYSCTL_HANDLER_ARGS)
620 int *name = (int *)arg1;
621 u_int namelen = arg2;
622 int rman_idx, res_idx;
624 struct resource *res;
626 struct u_resource ures;
632 if (bus_data_generation_check(name[0]))
638 * Find the indexed resource manager
640 TAILQ_FOREACH(rm, &rman_head, rm_link) {
648 * If the resource index is -1, we want details on the
652 urm.rm_handle = (uintptr_t)rm;
653 strlcpy(urm.rm_descr, rm->rm_descr, RM_TEXTLEN);
654 urm.rm_start = rm->rm_start;
655 urm.rm_size = rm->rm_end - rm->rm_start + 1;
656 urm.rm_type = rm->rm_type;
658 error = SYSCTL_OUT(req, &urm, sizeof(urm));
663 * Find the indexed resource and return it.
665 TAILQ_FOREACH(res, &rm->rm_list, r_link) {
666 if (res_idx-- == 0) {
667 ures.r_handle = (uintptr_t)res;
668 ures.r_parent = (uintptr_t)res->r_rm;
669 ures.r_device = (uintptr_t)res->r_dev;
670 if (res->r_dev != NULL) {
671 if (device_get_name(res->r_dev) != NULL) {
672 ksnprintf(ures.r_devname, RM_TEXTLEN,
674 device_get_name(res->r_dev),
675 device_get_unit(res->r_dev));
677 strlcpy(ures.r_devname, "nomatch",
681 ures.r_devname[0] = '\0';
683 ures.r_start = res->r_start;
684 ures.r_size = res->r_end - res->r_start + 1;
685 ures.r_flags = res->r_flags;
687 error = SYSCTL_OUT(req, &ures, sizeof(ures));
694 SYSCTL_NODE(_hw_bus, OID_AUTO, rman, CTLFLAG_RD, sysctl_rman,
695 "kernel resource manager");