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 $
30 * $DragonFly: src/sys/kern/subr_rman.c,v 1.15 2008/09/30 12:20:29 hasso 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 */
68 #include <sys/sysctl.h>
71 TUNABLE_INT("debug.rman_debug", &rman_debug);
72 SYSCTL_INT(_debug, OID_AUTO, rman_debug, CTLFLAG_RW,
73 &rman_debug, 0, "rman debug");
75 #define DPRINTF(params) if (rman_debug) kprintf params
77 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager");
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);
87 rman_init(struct rman *rm)
93 TAILQ_INIT(&rman_head);
94 lwkt_token_init(&rman_tok, 1, "rman");
97 if (rm->rm_type == RMAN_UNINIT)
99 if (rm->rm_type == RMAN_GAUGE)
100 panic("implement RMAN_GAUGE");
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)
106 lwkt_token_init(rm->rm_slock, 1, "rmanslock");
108 lwkt_gettoken(&rman_tok);
109 TAILQ_INSERT_TAIL(&rman_head, rm, rm_link);
110 lwkt_reltoken(&rman_tok);
115 * NB: this interface is not robust against programming errors which
116 * add multiple copies of the same region.
119 rman_manage_region(struct rman *rm, u_long start, u_long end)
121 struct resource *r, *s;
123 DPRINTF(("rman_manage_region: <%s> request: start %#lx, end %#lx\n",
124 rm->rm_descr, start, end));
125 r = kmalloc(sizeof *r, M_RMAN, M_NOWAIT | M_ZERO);
135 lwkt_gettoken(rm->rm_slock);
136 for (s = TAILQ_FIRST(&rm->rm_list);
137 s && s->r_end < r->r_start;
138 s = TAILQ_NEXT(s, r_link))
142 TAILQ_INSERT_TAIL(&rm->rm_list, r, r_link);
144 TAILQ_INSERT_BEFORE(s, r, r_link);
146 lwkt_reltoken(rm->rm_slock);
151 rman_fini(struct rman *rm)
155 lwkt_gettoken(rm->rm_slock);
156 TAILQ_FOREACH(r, &rm->rm_list, r_link) {
157 if (r->r_flags & RF_ALLOCATED) {
158 lwkt_reltoken(rm->rm_slock);
164 * There really should only be one of these if we are in this
165 * state and the code is working properly, but it can't hurt.
167 while (!TAILQ_EMPTY(&rm->rm_list)) {
168 r = TAILQ_FIRST(&rm->rm_list);
169 TAILQ_REMOVE(&rm->rm_list, r, r_link);
172 lwkt_reltoken(rm->rm_slock);
174 /* XXX what's the point of this if we are going to free the struct? */
175 lwkt_gettoken(&rman_tok);
176 TAILQ_REMOVE(&rman_head, rm, rm_link);
177 lwkt_reltoken(&rman_tok);
178 kfree(rm->rm_slock, M_RMAN);
184 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count,
185 u_int flags, struct device *dev)
188 struct resource *r, *s, *rv;
193 DPRINTF(("rman_reserve_resource: <%s> request: [%#lx, %#lx], length "
194 "%#lx, flags %u, device %s\n", rm->rm_descr, start, end,
196 dev == NULL ? "<null>" : device_get_nameunit(dev)));
197 want_activate = (flags & RF_ACTIVE);
200 lwkt_gettoken(rm->rm_slock);
202 for (r = TAILQ_FIRST(&rm->rm_list);
203 r && r->r_end < start;
204 r = TAILQ_NEXT(r, r_link))
208 DPRINTF(("could not find a region\n"));
213 * First try to find an acceptable totally-unshared region.
215 for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
216 DPRINTF(("considering [%#lx, %#lx]\n", s->r_start, s->r_end));
217 if (s->r_start > end) {
218 DPRINTF(("s->r_start (%#lx) > end (%#lx)\n",
222 if (s->r_flags & RF_ALLOCATED) {
223 DPRINTF(("region is allocated\n"));
226 rstart = max(s->r_start, start);
227 rstart = (rstart + ((1ul << RF_ALIGNMENT(flags))) - 1) &
228 ~((1ul << RF_ALIGNMENT(flags)) - 1);
229 rend = min(s->r_end, max(start + count, end));
230 DPRINTF(("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n",
231 rstart, rend, (rend - rstart + 1), count));
233 if ((rend - rstart + 1) >= count) {
234 DPRINTF(("candidate region: [%#lx, %#lx], size %#lx\n",
235 rstart, rend, (rend - rstart + 1)));
236 if ((s->r_end - s->r_start + 1) == count) {
237 DPRINTF(("candidate region is entire chunk\n"));
239 rv->r_flags |= RF_ALLOCATED | flags;
245 * If s->r_start < rstart and
246 * s->r_end > rstart + count - 1, then
247 * we need to split the region into three pieces
248 * (the middle one will get returned to the user).
249 * Otherwise, we are allocating at either the
250 * beginning or the end of s, so we only need to
251 * split it in two. The first case requires
252 * two new allocations; the second requires but one.
254 rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO);
257 rv->r_start = rstart;
258 rv->r_end = rstart + count - 1;
259 rv->r_flags = flags | RF_ALLOCATED;
264 if (s->r_start < rv->r_start && s->r_end > rv->r_end) {
265 DPRINTF(("splitting region in three parts: "
266 "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n",
267 s->r_start, rv->r_start - 1,
268 rv->r_start, rv->r_end,
269 rv->r_end + 1, s->r_end));
271 * We are allocating in the middle.
273 r = kmalloc(sizeof *r, M_RMAN,
280 r->r_start = rv->r_end + 1;
282 r->r_flags = s->r_flags;
286 s->r_end = rv->r_start - 1;
287 TAILQ_INSERT_AFTER(&rm->rm_list, s, rv,
289 TAILQ_INSERT_AFTER(&rm->rm_list, rv, r,
291 } else if (s->r_start == rv->r_start) {
292 DPRINTF(("allocating from the beginning\n"));
294 * We are allocating at the beginning.
296 s->r_start = rv->r_end + 1;
297 TAILQ_INSERT_BEFORE(s, rv, r_link);
299 DPRINTF(("allocating at the end\n"));
301 * We are allocating at the end.
303 s->r_end = rv->r_start - 1;
304 TAILQ_INSERT_AFTER(&rm->rm_list, s, rv,
312 * Now find an acceptable shared region, if the client's requirements
313 * allow sharing. By our implementation restriction, a candidate
314 * region must match exactly by both size and sharing type in order
315 * to be considered compatible with the client's request. (The
316 * former restriction could probably be lifted without too much
317 * additional work, but this does not seem warranted.)
319 DPRINTF(("no unshared regions found\n"));
320 if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0)
323 for (s = r; s; s = TAILQ_NEXT(s, r_link)) {
324 if (s->r_start > end)
326 if ((s->r_flags & flags) != flags)
328 rstart = max(s->r_start, start);
329 rend = min(s->r_end, max(start + count, end));
330 if (s->r_start >= start && s->r_end <= end
331 && (s->r_end - s->r_start + 1) == count) {
332 rv = kmalloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO);
335 rv->r_start = s->r_start;
336 rv->r_end = s->r_end;
337 rv->r_flags = s->r_flags &
338 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE);
341 if (s->r_sharehead == 0) {
342 s->r_sharehead = kmalloc(sizeof *s->r_sharehead,
345 if (s->r_sharehead == 0) {
350 LIST_INIT(s->r_sharehead);
351 LIST_INSERT_HEAD(s->r_sharehead, s,
353 s->r_flags |= RF_FIRSTSHARE;
355 rv->r_sharehead = s->r_sharehead;
356 LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink);
362 * We couldn't find anything.
366 * If the user specified RF_ACTIVE in the initial flags,
367 * which is reflected in `want_activate', we attempt to atomically
368 * activate the resource. If this fails, we release the resource
369 * and indicate overall failure. (This behavior probably doesn't
370 * make sense for RF_TIMESHARE-type resources.)
372 if (rv && want_activate) {
373 struct resource *whohas;
374 if (int_rman_activate_resource(rm, rv, &whohas)) {
375 int_rman_release_resource(rm, rv);
379 lwkt_reltoken(rm->rm_slock);
384 int_rman_activate_resource(struct rman *rm, struct resource *r,
385 struct resource **whohas)
391 * If we are not timesharing, then there is nothing much to do.
392 * If we already have the resource, then there is nothing at all to do.
393 * If we are not on a sharing list with anybody else, then there is
396 if ((r->r_flags & RF_TIMESHARE) == 0
397 || (r->r_flags & RF_ACTIVE) != 0
398 || r->r_sharehead == 0) {
399 r->r_flags |= RF_ACTIVE;
404 for (s = LIST_FIRST(r->r_sharehead); s && ok;
405 s = LIST_NEXT(s, r_sharelink)) {
406 if ((s->r_flags & RF_ACTIVE) != 0) {
412 r->r_flags |= RF_ACTIVE;
419 rman_activate_resource(struct resource *r)
422 struct resource *whohas;
426 lwkt_gettoken(rm->rm_slock);
427 rv = int_rman_activate_resource(rm, r, &whohas);
428 lwkt_reltoken(rm->rm_slock);
436 rman_await_resource(struct resource *r, int slpflags, int timo)
439 struct resource *whohas;
444 lwkt_gettoken(rm->rm_slock);
445 rv = int_rman_activate_resource(rm, r, &whohas);
447 return (rv); /* returns with ilock held */
449 if (r->r_sharehead == 0)
450 panic("rman_await_resource");
452 * A critical section will hopefully will prevent a race
453 * between lwkt_reltoken and tsleep where a process
454 * could conceivably get in and release the resource
455 * before we have a chance to sleep on it. YYY
458 whohas->r_flags |= RF_WANTED;
459 rv = tsleep(r->r_sharehead, slpflags, "rmwait", timo);
461 lwkt_reltoken(rm->rm_slock);
472 int_rman_deactivate_resource(struct resource *r)
477 r->r_flags &= ~RF_ACTIVE;
478 if (r->r_flags & RF_WANTED) {
479 r->r_flags &= ~RF_WANTED;
480 wakeup(r->r_sharehead);
486 rman_deactivate_resource(struct resource *r)
491 lwkt_gettoken(rm->rm_slock);
492 int_rman_deactivate_resource(r);
493 lwkt_reltoken(rm->rm_slock);
498 int_rman_release_resource(struct rman *rm, struct resource *r)
500 struct resource *s, *t;
502 if (r->r_flags & RF_ACTIVE)
503 int_rman_deactivate_resource(r);
506 * Check for a sharing list first. If there is one, then we don't
507 * have to think as hard.
509 if (r->r_sharehead) {
511 * If a sharing list exists, then we know there are at
514 * If we are in the main circleq, appoint someone else.
516 LIST_REMOVE(r, r_sharelink);
517 s = LIST_FIRST(r->r_sharehead);
518 if (r->r_flags & RF_FIRSTSHARE) {
519 s->r_flags |= RF_FIRSTSHARE;
520 TAILQ_INSERT_BEFORE(r, s, r_link);
521 TAILQ_REMOVE(&rm->rm_list, r, r_link);
525 * Make sure that the sharing list goes away completely
526 * if the resource is no longer being shared at all.
528 if (LIST_NEXT(s, r_sharelink) == 0) {
529 kfree(s->r_sharehead, M_RMAN);
531 s->r_flags &= ~RF_FIRSTSHARE;
537 * Look at the adjacent resources in the list and see if our
538 * segment can be merged with any of them.
540 s = TAILQ_PREV(r, resource_head, r_link);
541 t = TAILQ_NEXT(r, r_link);
543 if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0
544 && t != NULL && (t->r_flags & RF_ALLOCATED) == 0) {
546 * Merge all three segments.
549 TAILQ_REMOVE(&rm->rm_list, r, r_link);
550 TAILQ_REMOVE(&rm->rm_list, t, r_link);
552 } else if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0) {
554 * Merge previous segment with ours.
557 TAILQ_REMOVE(&rm->rm_list, r, r_link);
558 } else if (t != NULL && (t->r_flags & RF_ALLOCATED) == 0) {
560 * Merge next segment with ours.
562 t->r_start = r->r_start;
563 TAILQ_REMOVE(&rm->rm_list, r, r_link);
566 * At this point, we know there is nothing we
567 * can potentially merge with, because on each
568 * side, there is either nothing there or what is
569 * there is still allocated. In that case, we don't
570 * want to remove r from the list; we simply want to
571 * change it to an unallocated region and return
572 * without freeing anything.
574 r->r_flags &= ~RF_ALLOCATED;
584 rman_release_resource(struct resource *r)
586 struct rman *rm = r->r_rm;
589 lwkt_gettoken(rm->rm_slock);
590 rv = int_rman_release_resource(rm, r);
591 lwkt_reltoken(rm->rm_slock);
596 rman_make_alignment_flags(uint32_t size)
601 * Find the hightest bit set, and add one if more than one bit
602 * set. We're effectively computing the ceil(log2(size)) here.
604 for (i = 32; i > 0; i--)
607 if (~(1 << i) & size)
610 return(RF_ALIGNMENT_LOG2(i));
614 * Sysctl interface for scanning the resource lists.
616 * We take two input parameters; the index into the list of resource
617 * managers, and the resource offset into the list.
620 sysctl_rman(SYSCTL_HANDLER_ARGS)
622 int *name = (int *)arg1;
623 u_int namelen = arg2;
624 int rman_idx, res_idx;
626 struct resource *res;
628 struct u_resource ures;
634 if (bus_data_generation_check(name[0]))
640 * Find the indexed resource manager
642 TAILQ_FOREACH(rm, &rman_head, rm_link) {
650 * If the resource index is -1, we want details on the
654 urm.rm_handle = (uintptr_t)rm;
655 strlcpy(urm.rm_descr, rm->rm_descr, RM_TEXTLEN);
656 urm.rm_start = rm->rm_start;
657 urm.rm_size = rm->rm_end - rm->rm_start + 1;
658 urm.rm_type = rm->rm_type;
660 error = SYSCTL_OUT(req, &urm, sizeof(urm));
665 * Find the indexed resource and return it.
667 TAILQ_FOREACH(res, &rm->rm_list, r_link) {
668 if (res_idx-- == 0) {
669 ures.r_handle = (uintptr_t)res;
670 ures.r_parent = (uintptr_t)res->r_rm;
671 ures.r_device = (uintptr_t)res->r_dev;
672 if (res->r_dev != NULL) {
673 if (device_get_name(res->r_dev) != NULL) {
674 ksnprintf(ures.r_devname, RM_TEXTLEN,
676 device_get_name(res->r_dev),
677 device_get_unit(res->r_dev));
679 strlcpy(ures.r_devname, "nomatch",
683 ures.r_devname[0] = '\0';
685 ures.r_start = res->r_start;
686 ures.r_size = res->r_end - res->r_start + 1;
687 ures.r_flags = res->r_flags;
689 error = SYSCTL_OUT(req, &ures, sizeof(ures));
696 SYSCTL_NODE(_hw_bus, OID_AUTO, rman, CTLFLAG_RD, sysctl_rman,
697 "kernel resource manager");