subr_rman.c revision 102572
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 * $FreeBSD: head/sys/kern/subr_rman.c 102572 2002-08-29 12:39:21Z iwasaki $ 30 */ 31 32/* 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 40 * the allocation. 41 * 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 52 * implemented yet. 53 * 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 57 * permitted. 58 */ 59 60#include <sys/param.h> 61#include <sys/systm.h> 62#include <sys/kernel.h> 63#include <sys/lock.h> 64#include <sys/malloc.h> 65#include <sys/mutex.h> 66#include <sys/bus.h> /* XXX debugging */ 67#include <machine/bus.h> 68#include <sys/rman.h> 69 70#ifdef RMAN_DEBUG 71#define DPRINTF(params) printf##params 72#else 73#define DPRINTF(params) 74#endif 75 76static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager"); 77 78struct rman_head rman_head; 79static struct mtx rman_mtx; /* mutex to protect rman_head */ 80static int int_rman_activate_resource(struct rman *rm, struct resource *r, 81 struct resource **whohas); 82static int int_rman_deactivate_resource(struct resource *r); 83static int int_rman_release_resource(struct rman *rm, struct resource *r); 84 85int 86rman_init(struct rman *rm) 87{ 88 static int once; 89 90 if (once == 0) { 91 once = 1; 92 TAILQ_INIT(&rman_head); 93 mtx_init(&rman_mtx, "rman head", NULL, MTX_DEF); 94 } 95 96 if (rm->rm_type == RMAN_UNINIT) 97 panic("rman_init"); 98 if (rm->rm_type == RMAN_GAUGE) 99 panic("implement RMAN_GAUGE"); 100 101 TAILQ_INIT(&rm->rm_list); 102 rm->rm_mtx = malloc(sizeof *rm->rm_mtx, M_RMAN, M_NOWAIT | M_ZERO); 103 if (rm->rm_mtx == 0) 104 return ENOMEM; 105 mtx_init(rm->rm_mtx, "rman", NULL, MTX_DEF); 106 107 mtx_lock(&rman_mtx); 108 TAILQ_INSERT_TAIL(&rman_head, rm, rm_link); 109 mtx_unlock(&rman_mtx); 110 return 0; 111} 112 113/* 114 * NB: this interface is not robust against programming errors which 115 * add multiple copies of the same region. 116 */ 117int 118rman_manage_region(struct rman *rm, u_long start, u_long end) 119{ 120 struct resource *r, *s; 121 122 r = malloc(sizeof *r, M_RMAN, M_NOWAIT | M_ZERO); 123 if (r == 0) 124 return ENOMEM; 125 r->r_start = start; 126 r->r_end = end; 127 r->r_rm = rm; 128 129 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)) 133 ; 134 135 if (s == NULL) { 136 TAILQ_INSERT_TAIL(&rm->rm_list, r, r_link); 137 } else { 138 TAILQ_INSERT_BEFORE(s, r, r_link); 139 } 140 141 mtx_unlock(rm->rm_mtx); 142 return 0; 143} 144 145int 146rman_fini(struct rman *rm) 147{ 148 struct resource *r; 149 150 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); 154 return EBUSY; 155 } 156 } 157 158 /* 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. 161 */ 162 while (!TAILQ_EMPTY(&rm->rm_list)) { 163 r = TAILQ_FIRST(&rm->rm_list); 164 TAILQ_REMOVE(&rm->rm_list, r, r_link); 165 free(r, M_RMAN); 166 } 167 mtx_unlock(rm->rm_mtx); 168 mtx_lock(&rman_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); 173 174 return 0; 175} 176 177struct resource * 178rman_reserve_resource_bound(struct rman *rm, u_long start, u_long end, 179 u_long count, u_long bound, u_int flags, 180 struct device *dev) 181{ 182 u_int want_activate; 183 struct resource *r, *s, *rv; 184 u_long rstart, rend, amask, bmask; 185 186 rv = 0; 187 188 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); 192 flags &= ~RF_ACTIVE; 193 194 mtx_lock(rm->rm_mtx); 195 196 for (r = TAILQ_FIRST(&rm->rm_list); 197 r && r->r_end < start; 198 r = TAILQ_NEXT(r, r_link)) 199 ; 200 201 if (r == NULL) { 202 DPRINTF(("could not find a region\n")); 203 goto out; 204 } 205 206 amask = (1ul << RF_ALIGNMENT(flags)) - 1; 207 /* If bound is 0, bmask will also be 0 */ 208 bmask = ~(bound - 1); 209 /* 210 * First try to find an acceptable totally-unshared region. 211 */ 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)); 216 break; 217 } 218 if (s->r_flags & RF_ALLOCATED) { 219 DPRINTF(("region is allocated\n")); 220 continue; 221 } 222 rstart = ulmax(s->r_start, start); 223 /* 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. 227 */ 228 do { 229 rstart = (rstart + amask) & ~amask; 230 if (((rstart ^ (rstart + count)) & bmask) != 0) 231 rstart += bound - (rstart & ~bmask); 232 } while ((rstart & amask) != 0 && rstart < end && 233 rstart < s->r_end); 234 rend = ulmin(s->r_end, ulmax(rstart + count, end)); 235 if (rstart > rend) { 236 DPRINTF(("adjusted start exceeds end\n")); 237 continue; 238 } 239 DPRINTF(("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n", 240 rstart, rend, (rend - rstart + 1), count)); 241 242 if ((rend - rstart + 1) >= count) { 243 DPRINTF(("candidate region: [%#lx, %#lx], size %#lx\n", 244 rend, rstart, (rend - rstart + 1))); 245 if ((s->r_end - s->r_start + 1) == count) { 246 DPRINTF(("candidate region is entire chunk\n")); 247 rv = s; 248 rv->r_flags |= RF_ALLOCATED | flags; 249 rv->r_dev = dev; 250 goto out; 251 } 252 253 /* 254 * If s->r_start < rstart and 255 * s->r_end > rstart + count - 1, then 256 * we need to split the region into three pieces 257 * (the middle one will get returned to the user). 258 * Otherwise, we are allocating at either the 259 * beginning or the end of s, so we only need to 260 * split it in two. The first case requires 261 * two new allocations; the second requires but one. 262 */ 263 rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO); 264 if (rv == 0) 265 goto out; 266 rv->r_start = rstart; 267 rv->r_end = rstart + count - 1; 268 rv->r_flags = flags | RF_ALLOCATED; 269 rv->r_dev = dev; 270 rv->r_rm = rm; 271 272 if (s->r_start < rv->r_start && s->r_end > rv->r_end) { 273 DPRINTF(("splitting region in three parts: " 274 "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n", 275 s->r_start, rv->r_start - 1, 276 rv->r_start, rv->r_end, 277 rv->r_end + 1, s->r_end)); 278 /* 279 * We are allocating in the middle. 280 */ 281 r = malloc(sizeof *r, M_RMAN, M_NOWAIT|M_ZERO); 282 if (r == 0) { 283 free(rv, M_RMAN); 284 rv = 0; 285 goto out; 286 } 287 r->r_start = rv->r_end + 1; 288 r->r_end = s->r_end; 289 r->r_flags = s->r_flags; 290 r->r_rm = rm; 291 s->r_end = rv->r_start - 1; 292 TAILQ_INSERT_AFTER(&rm->rm_list, s, rv, 293 r_link); 294 TAILQ_INSERT_AFTER(&rm->rm_list, rv, r, 295 r_link); 296 } else if (s->r_start == rv->r_start) { 297 DPRINTF(("allocating from the beginning\n")); 298 /* 299 * We are allocating at the beginning. 300 */ 301 s->r_start = rv->r_end + 1; 302 TAILQ_INSERT_BEFORE(s, rv, r_link); 303 } else { 304 DPRINTF(("allocating at the end\n")); 305 /* 306 * We are allocating at the end. 307 */ 308 s->r_end = rv->r_start - 1; 309 TAILQ_INSERT_AFTER(&rm->rm_list, s, rv, 310 r_link); 311 } 312 goto out; 313 } 314 } 315 316 /* 317 * Now find an acceptable shared region, if the client's requirements 318 * allow sharing. By our implementation restriction, a candidate 319 * region must match exactly by both size and sharing type in order 320 * to be considered compatible with the client's request. (The 321 * former restriction could probably be lifted without too much 322 * additional work, but this does not seem warranted.) 323 */ 324 DPRINTF(("no unshared regions found\n")); 325 if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0) 326 goto out; 327 328 for (s = r; s; s = TAILQ_NEXT(s, r_link)) { 329 if (s->r_start > end) 330 break; 331 if ((s->r_flags & flags) != flags) 332 continue; 333 rstart = ulmax(s->r_start, start); 334 rend = ulmin(s->r_end, ulmax(start + count, end)); 335 if (s->r_start >= start && s->r_end <= end 336 && (s->r_end - s->r_start + 1) == count && 337 (s->r_start & amask) == 0 && 338 ((s->r_start ^ s->r_end) & bmask) == 0) { 339 rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO); 340 if (rv == 0) 341 goto out; 342 rv->r_start = s->r_start; 343 rv->r_end = s->r_end; 344 rv->r_flags = s->r_flags & 345 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE); 346 rv->r_dev = dev; 347 rv->r_rm = rm; 348 if (s->r_sharehead == 0) { 349 s->r_sharehead = malloc(sizeof *s->r_sharehead, 350 M_RMAN, M_NOWAIT | M_ZERO); 351 if (s->r_sharehead == 0) { 352 free(rv, M_RMAN); 353 rv = 0; 354 goto out; 355 } 356 LIST_INIT(s->r_sharehead); 357 LIST_INSERT_HEAD(s->r_sharehead, s, 358 r_sharelink); 359 s->r_flags |= RF_FIRSTSHARE; 360 } 361 rv->r_sharehead = s->r_sharehead; 362 LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink); 363 goto out; 364 } 365 } 366 367 /* 368 * We couldn't find anything. 369 */ 370out: 371 /* 372 * If the user specified RF_ACTIVE in the initial flags, 373 * which is reflected in `want_activate', we attempt to atomically 374 * activate the resource. If this fails, we release the resource 375 * and indicate overall failure. (This behavior probably doesn't 376 * make sense for RF_TIMESHARE-type resources.) 377 */ 378 if (rv && want_activate) { 379 struct resource *whohas; 380 if (int_rman_activate_resource(rm, rv, &whohas)) { 381 int_rman_release_resource(rm, rv); 382 rv = 0; 383 } 384 } 385 386 mtx_unlock(rm->rm_mtx); 387 return (rv); 388} 389 390struct resource * 391rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count, 392 u_int flags, struct device *dev) 393{ 394 395 return (rman_reserve_resource_bound(rm, start, end, count, 0, flags, 396 dev)); 397} 398 399static int 400int_rman_activate_resource(struct rman *rm, struct resource *r, 401 struct resource **whohas) 402{ 403 struct resource *s; 404 int ok; 405 406 /* 407 * If we are not timesharing, then there is nothing much to do. 408 * If we already have the resource, then there is nothing at all to do. 409 * If we are not on a sharing list with anybody else, then there is 410 * little to do. 411 */ 412 if ((r->r_flags & RF_TIMESHARE) == 0 413 || (r->r_flags & RF_ACTIVE) != 0 414 || r->r_sharehead == 0) { 415 r->r_flags |= RF_ACTIVE; 416 return 0; 417 } 418 419 ok = 1; 420 for (s = LIST_FIRST(r->r_sharehead); s && ok; 421 s = LIST_NEXT(s, r_sharelink)) { 422 if ((s->r_flags & RF_ACTIVE) != 0) { 423 ok = 0; 424 *whohas = s; 425 } 426 } 427 if (ok) { 428 r->r_flags |= RF_ACTIVE; 429 return 0; 430 } 431 return EBUSY; 432} 433 434int 435rman_activate_resource(struct resource *r) 436{ 437 int rv; 438 struct resource *whohas; 439 struct rman *rm; 440 441 rm = r->r_rm; 442 mtx_lock(rm->rm_mtx); 443 rv = int_rman_activate_resource(rm, r, &whohas); 444 mtx_unlock(rm->rm_mtx); 445 return rv; 446} 447 448int 449rman_await_resource(struct resource *r, int pri, int timo) 450{ 451 int rv; 452 struct resource *whohas; 453 struct rman *rm; 454 455 rm = r->r_rm; 456 mtx_lock(rm->rm_mtx); 457 for (;;) { 458 rv = int_rman_activate_resource(rm, r, &whohas); 459 if (rv != EBUSY) 460 return (rv); /* returns with mutex held */ 461 462 if (r->r_sharehead == 0) 463 panic("rman_await_resource"); 464 whohas->r_flags |= RF_WANTED; 465 rv = msleep(r->r_sharehead, rm->rm_mtx, pri, "rmwait", timo); 466 if (rv) { 467 mtx_unlock(rm->rm_mtx); 468 return (rv); 469 } 470 } 471} 472 473static int 474int_rman_deactivate_resource(struct resource *r) 475{ 476 struct rman *rm; 477 478 rm = r->r_rm; 479 r->r_flags &= ~RF_ACTIVE; 480 if (r->r_flags & RF_WANTED) { 481 r->r_flags &= ~RF_WANTED; 482 wakeup(r->r_sharehead); 483 } 484 return 0; 485} 486 487int 488rman_deactivate_resource(struct resource *r) 489{ 490 struct rman *rm; 491 492 rm = r->r_rm; 493 mtx_lock(rm->rm_mtx); 494 int_rman_deactivate_resource(r); 495 mtx_unlock(rm->rm_mtx); 496 return 0; 497} 498 499static int 500int_rman_release_resource(struct rman *rm, struct resource *r) 501{ 502 struct resource *s, *t; 503 504 if (r->r_flags & RF_ACTIVE) 505 int_rman_deactivate_resource(r); 506 507 /* 508 * Check for a sharing list first. If there is one, then we don't 509 * have to think as hard. 510 */ 511 if (r->r_sharehead) { 512 /* 513 * If a sharing list exists, then we know there are at 514 * least two sharers. 515 * 516 * If we are in the main circleq, appoint someone else. 517 */ 518 LIST_REMOVE(r, r_sharelink); 519 s = LIST_FIRST(r->r_sharehead); 520 if (r->r_flags & RF_FIRSTSHARE) { 521 s->r_flags |= RF_FIRSTSHARE; 522 TAILQ_INSERT_BEFORE(r, s, r_link); 523 TAILQ_REMOVE(&rm->rm_list, r, r_link); 524 } 525 526 /* 527 * Make sure that the sharing list goes away completely 528 * if the resource is no longer being shared at all. 529 */ 530 if (LIST_NEXT(s, r_sharelink) == 0) { 531 free(s->r_sharehead, M_RMAN); 532 s->r_sharehead = 0; 533 s->r_flags &= ~RF_FIRSTSHARE; 534 } 535 goto out; 536 } 537 538 /* 539 * Look at the adjacent resources in the list and see if our 540 * segment can be merged with any of them. 541 */ 542 s = TAILQ_PREV(r, resource_head, r_link); 543 t = TAILQ_NEXT(r, r_link); 544 545 if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0 546 && t != NULL && (t->r_flags & RF_ALLOCATED) == 0) { 547 /* 548 * Merge all three segments. 549 */ 550 s->r_end = t->r_end; 551 TAILQ_REMOVE(&rm->rm_list, r, r_link); 552 TAILQ_REMOVE(&rm->rm_list, t, r_link); 553 free(t, M_RMAN); 554 } else if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0) { 555 /* 556 * Merge previous segment with ours. 557 */ 558 s->r_end = r->r_end; 559 TAILQ_REMOVE(&rm->rm_list, r, r_link); 560 } else if (t != NULL && (t->r_flags & RF_ALLOCATED) == 0) { 561 /* 562 * Merge next segment with ours. 563 */ 564 t->r_start = r->r_start; 565 TAILQ_REMOVE(&rm->rm_list, r, r_link); 566 } else { 567 /* 568 * At this point, we know there is nothing we 569 * can potentially merge with, because on each 570 * side, there is either nothing there or what is 571 * there is still allocated. In that case, we don't 572 * want to remove r from the list; we simply want to 573 * change it to an unallocated region and return 574 * without freeing anything. 575 */ 576 r->r_flags &= ~RF_ALLOCATED; 577 return 0; 578 } 579 580out: 581 free(r, M_RMAN); 582 return 0; 583} 584 585int 586rman_release_resource(struct resource *r) 587{ 588 int rv; 589 struct rman *rm = r->r_rm; 590 591 mtx_lock(rm->rm_mtx); 592 rv = int_rman_release_resource(rm, r); 593 mtx_unlock(rm->rm_mtx); 594 return (rv); 595} 596 597uint32_t 598rman_make_alignment_flags(uint32_t size) 599{ 600 int i; 601 602 /* 603 * Find the hightest bit set, and add one if more than one bit 604 * set. We're effectively computing the ceil(log2(size)) here. 605 */ 606 for (i = 31; i > 0; i--) 607 if ((1 << i) & size) 608 break; 609 if (~(1 << i) & size) 610 i++; 611 612 return(RF_ALIGNMENT_LOG2(i)); 613} 614