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 * $FreeBSD$ 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 76 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager"); 77 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); 84 85 int 86 rman_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", 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); 103 if (rm->rm_mtx == 0) 104 return ENOMEM; 105 mtx_init(rm->rm_mtx, "rman", 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 */ 117 int 118 rman_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_sharehead = 0; 126 r->r_start = start; 127 r->r_end = end; 128 r->r_flags = 0; 129 r->r_dev = 0; 130 r->r_rm = rm; 131 132 mtx_lock(rm->rm_mtx); 133 for (s = TAILQ_FIRST(&rm->rm_list); 134 s && s->r_end < r->r_start; 135 s = TAILQ_NEXT(s, r_link)) 136 ; 137 138 if (s == NULL) { 139 TAILQ_INSERT_TAIL(&rm->rm_list, r, r_link); 140 } else { 141 TAILQ_INSERT_BEFORE(s, r, r_link); 142 } 143 144 mtx_unlock(rm->rm_mtx); 145 return 0; 146 } 147 148 int 149 rman_fini(struct rman *rm) 150 { 151 struct resource *r; 152 153 mtx_lock(rm->rm_mtx); 154 TAILQ_FOREACH(r, &rm->rm_list, r_link) { 155 if (r->r_flags & RF_ALLOCATED) { 156 mtx_unlock(rm->rm_mtx); 157 return EBUSY; 158 } 159 } 160 161 /* 162 * There really should only be one of these if we are in this 163 * state and the code is working properly, but it can't hurt. 164 */ 165 while (!TAILQ_EMPTY(&rm->rm_list)) { 166 r = TAILQ_FIRST(&rm->rm_list); 167 TAILQ_REMOVE(&rm->rm_list, r, r_link); 168 free(r, M_RMAN); 169 } 170 mtx_unlock(rm->rm_mtx); 171 mtx_lock(&rman_mtx); 172 TAILQ_REMOVE(&rman_head, rm, rm_link); 173 mtx_unlock(&rman_mtx); 174 mtx_destroy(rm->rm_mtx); 175 free(rm->rm_mtx, M_RMAN); 176 177 return 0; 178 } 179 180 struct resource * 181 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count, 182 u_int flags, struct device *dev) 183 { 184 u_int want_activate; 185 struct resource *r, *s, *rv; 186 u_long rstart, rend; 187 188 rv = 0; 189 190 DPRINTF(("rman_reserve_resource: <%s> request: [%#lx, %#lx], length " 191 "%#lx, flags %u, device %s%d\n", rm->rm_descr, start, end, 192 count, flags, device_get_name(dev), device_get_unit(dev))); 193 want_activate = (flags & RF_ACTIVE); 194 flags &= ~RF_ACTIVE; 195 196 mtx_lock(rm->rm_mtx); 197 198 for (r = TAILQ_FIRST(&rm->rm_list); 199 r && r->r_end < start; 200 r = TAILQ_NEXT(r, r_link)) 201 ; 202 203 if (r == NULL) { 204 DPRINTF(("could not find a region\n")); 205 goto out; 206 } 207 208 /* 209 * First try to find an acceptable totally-unshared region. 210 */ 211 for (s = r; s; s = TAILQ_NEXT(s, r_link)) { 212 DPRINTF(("considering [%#lx, %#lx]\n", s->r_start, s->r_end)); 213 if (s->r_start > end) { 214 DPRINTF(("s->r_start (%#lx) > end (%#lx)\n", s->r_start, end)); 215 break; 216 } 217 if (s->r_flags & RF_ALLOCATED) { 218 DPRINTF(("region is allocated\n")); 219 continue; 220 } 221 rstart = max(s->r_start, start); 222 rstart = (rstart + ((1ul << RF_ALIGNMENT(flags))) - 1) & 223 ~((1ul << RF_ALIGNMENT(flags)) - 1); 224 rend = min(s->r_end, max(rstart + count, end)); 225 DPRINTF(("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n", 226 rstart, rend, (rend - rstart + 1), count)); 227 228 if ((rend - rstart + 1) >= count) { 229 DPRINTF(("candidate region: [%#lx, %#lx], size %#lx\n", 230 rend, rstart, (rend - rstart + 1))); 231 if ((s->r_end - s->r_start + 1) == count) { 232 DPRINTF(("candidate region is entire chunk\n")); 233 rv = s; 234 rv->r_flags |= RF_ALLOCATED | flags; 235 rv->r_dev = dev; 236 goto out; 237 } 238 239 /* 240 * If s->r_start < rstart and 241 * s->r_end > rstart + count - 1, then 242 * we need to split the region into three pieces 243 * (the middle one will get returned to the user). 244 * Otherwise, we are allocating at either the 245 * beginning or the end of s, so we only need to 246 * split it in two. The first case requires 247 * two new allocations; the second requires but one. 248 */ 249 rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO); 250 if (rv == 0) 251 goto out; 252 rv->r_start = rstart; 253 rv->r_end = rstart + count - 1; 254 rv->r_flags = flags | RF_ALLOCATED; 255 rv->r_dev = dev; 256 rv->r_sharehead = 0; 257 rv->r_rm = rm; 258 259 if (s->r_start < rv->r_start && s->r_end > rv->r_end) { 260 DPRINTF(("splitting region in three parts: " 261 "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n", 262 s->r_start, rv->r_start - 1, 263 rv->r_start, rv->r_end, 264 rv->r_end + 1, s->r_end)); 265 /* 266 * We are allocating in the middle. 267 */ 268 r = malloc(sizeof *r, M_RMAN, M_NOWAIT|M_ZERO); 269 if (r == 0) { 270 free(rv, M_RMAN); 271 rv = 0; 272 goto out; 273 } 274 r->r_start = rv->r_end + 1; 275 r->r_end = s->r_end; 276 r->r_flags = s->r_flags; 277 r->r_dev = 0; 278 r->r_sharehead = 0; 279 r->r_rm = rm; 280 s->r_end = rv->r_start - 1; 281 TAILQ_INSERT_AFTER(&rm->rm_list, s, rv, 282 r_link); 283 TAILQ_INSERT_AFTER(&rm->rm_list, rv, r, 284 r_link); 285 } else if (s->r_start == rv->r_start) { 286 DPRINTF(("allocating from the beginning\n")); 287 /* 288 * We are allocating at the beginning. 289 */ 290 s->r_start = rv->r_end + 1; 291 TAILQ_INSERT_BEFORE(s, rv, r_link); 292 } else { 293 DPRINTF(("allocating at the end\n")); 294 /* 295 * We are allocating at the end. 296 */ 297 s->r_end = rv->r_start - 1; 298 TAILQ_INSERT_AFTER(&rm->rm_list, s, rv, 299 r_link); 300 } 301 goto out; 302 } 303 } 304 305 /* 306 * Now find an acceptable shared region, if the client's requirements 307 * allow sharing. By our implementation restriction, a candidate 308 * region must match exactly by both size and sharing type in order 309 * to be considered compatible with the client's request. (The 310 * former restriction could probably be lifted without too much 311 * additional work, but this does not seem warranted.) 312 */ 313 DPRINTF(("no unshared regions found\n")); 314 if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0) 315 goto out; 316 317 for (s = r; s; s = TAILQ_NEXT(s, r_link)) { 318 if (s->r_start > end) 319 break; 320 if ((s->r_flags & flags) != flags) 321 continue; 322 rstart = max(s->r_start, start); 323 rend = min(s->r_end, max(start + count, end)); 324 if (s->r_start >= start && s->r_end <= end 325 && (s->r_end - s->r_start + 1) == count) { 326 rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT | M_ZERO); 327 if (rv == 0) 328 goto out; 329 rv->r_start = s->r_start; 330 rv->r_end = s->r_end; 331 rv->r_flags = s->r_flags & 332 (RF_ALLOCATED | RF_SHAREABLE | RF_TIMESHARE); 333 rv->r_dev = dev; 334 rv->r_rm = rm; 335 if (s->r_sharehead == 0) { 336 s->r_sharehead = malloc(sizeof *s->r_sharehead, 337 M_RMAN, M_NOWAIT | M_ZERO); 338 if (s->r_sharehead == 0) { 339 free(rv, M_RMAN); 340 rv = 0; 341 goto out; 342 } 343 LIST_INIT(s->r_sharehead); 344 LIST_INSERT_HEAD(s->r_sharehead, s, 345 r_sharelink); 346 s->r_flags |= RF_FIRSTSHARE; 347 } 348 rv->r_sharehead = s->r_sharehead; 349 LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink); 350 goto out; 351 } 352 } 353 354 /* 355 * We couldn't find anything. 356 */ 357 out: 358 /* 359 * If the user specified RF_ACTIVE in the initial flags, 360 * which is reflected in `want_activate', we attempt to atomically 361 * activate the resource. If this fails, we release the resource 362 * and indicate overall failure. (This behavior probably doesn't 363 * make sense for RF_TIMESHARE-type resources.) 364 */ 365 if (rv && want_activate) { 366 struct resource *whohas; 367 if (int_rman_activate_resource(rm, rv, &whohas)) { 368 int_rman_release_resource(rm, rv); 369 rv = 0; 370 } 371 } 372 373 mtx_unlock(rm->rm_mtx); 374 return (rv); 375 } 376 377 static int 378 int_rman_activate_resource(struct rman *rm, struct resource *r, 379 struct resource **whohas) 380 { 381 struct resource *s; 382 int ok; 383 384 /* 385 * If we are not timesharing, then there is nothing much to do. 386 * If we already have the resource, then there is nothing at all to do. 387 * If we are not on a sharing list with anybody else, then there is 388 * little to do. 389 */ 390 if ((r->r_flags & RF_TIMESHARE) == 0 391 || (r->r_flags & RF_ACTIVE) != 0 392 || r->r_sharehead == 0) { 393 r->r_flags |= RF_ACTIVE; 394 return 0; 395 } 396 397 ok = 1; 398 for (s = LIST_FIRST(r->r_sharehead); s && ok; 399 s = LIST_NEXT(s, r_sharelink)) { 400 if ((s->r_flags & RF_ACTIVE) != 0) { 401 ok = 0; 402 *whohas = s; 403 } 404 } 405 if (ok) { 406 r->r_flags |= RF_ACTIVE; 407 return 0; 408 } 409 return EBUSY; 410 } 411 412 int 413 rman_activate_resource(struct resource *r) 414 { 415 int rv; 416 struct resource *whohas; 417 struct rman *rm; 418 419 rm = r->r_rm; 420 mtx_lock(rm->rm_mtx); 421 rv = int_rman_activate_resource(rm, r, &whohas); 422 mtx_unlock(rm->rm_mtx); 423 return rv; 424 } 425 426 int 427 rman_await_resource(struct resource *r, int pri, int timo) 428 { 429 int rv, s; 430 struct resource *whohas; 431 struct rman *rm; 432 433 rm = r->r_rm; 434 for (;;) { 435 mtx_lock(rm->rm_mtx); 436 rv = int_rman_activate_resource(rm, r, &whohas); 437 if (rv != EBUSY) 438 return (rv); /* returns with mutex held */ 439 440 if (r->r_sharehead == 0) 441 panic("rman_await_resource"); 442 /* 443 * splhigh hopefully will prevent a race between 444 * mtx_unlock and tsleep where a process 445 * could conceivably get in and release the resource 446 * before we have a chance to sleep on it. 447 */ 448 s = splhigh(); 449 whohas->r_flags |= RF_WANTED; 450 mtx_unlock(rm->rm_mtx); 451 rv = tsleep(r->r_sharehead, pri, "rmwait", timo); 452 if (rv) { 453 splx(s); 454 return rv; 455 } 456 mtx_lock(rm->rm_mtx); 457 splx(s); 458 } 459 } 460 461 static int 462 int_rman_deactivate_resource(struct resource *r) 463 { 464 struct rman *rm; 465 466 rm = r->r_rm; 467 r->r_flags &= ~RF_ACTIVE; 468 if (r->r_flags & RF_WANTED) { 469 r->r_flags &= ~RF_WANTED; 470 wakeup(r->r_sharehead); 471 } 472 return 0; 473 } 474 475 int 476 rman_deactivate_resource(struct resource *r) 477 { 478 struct rman *rm; 479 480 rm = r->r_rm; 481 mtx_lock(rm->rm_mtx); 482 int_rman_deactivate_resource(r); 483 mtx_unlock(rm->rm_mtx); 484 return 0; 485 } 486 487 static int 488 int_rman_release_resource(struct rman *rm, struct resource *r) 489 { 490 struct resource *s, *t; 491 492 if (r->r_flags & RF_ACTIVE) 493 int_rman_deactivate_resource(r); 494 495 /* 496 * Check for a sharing list first. If there is one, then we don't 497 * have to think as hard. 498 */ 499 if (r->r_sharehead) { 500 /* 501 * If a sharing list exists, then we know there are at 502 * least two sharers. 503 * 504 * If we are in the main circleq, appoint someone else. 505 */ 506 LIST_REMOVE(r, r_sharelink); 507 s = LIST_FIRST(r->r_sharehead); 508 if (r->r_flags & RF_FIRSTSHARE) { 509 s->r_flags |= RF_FIRSTSHARE; 510 TAILQ_INSERT_BEFORE(r, s, r_link); 511 TAILQ_REMOVE(&rm->rm_list, r, r_link); 512 } 513 514 /* 515 * Make sure that the sharing list goes away completely 516 * if the resource is no longer being shared at all. 517 */ 518 if (LIST_NEXT(s, r_sharelink) == 0) { 519 free(s->r_sharehead, M_RMAN); 520 s->r_sharehead = 0; 521 s->r_flags &= ~RF_FIRSTSHARE; 522 } 523 goto out; 524 } 525 526 /* 527 * Look at the adjacent resources in the list and see if our 528 * segment can be merged with any of them. 529 */ 530 s = TAILQ_PREV(r, resource_head, r_link); 531 t = TAILQ_NEXT(r, r_link); 532 533 if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0 534 && t != NULL && (t->r_flags & RF_ALLOCATED) == 0) { 535 /* 536 * Merge all three segments. 537 */ 538 s->r_end = t->r_end; 539 TAILQ_REMOVE(&rm->rm_list, r, r_link); 540 TAILQ_REMOVE(&rm->rm_list, t, r_link); 541 free(t, M_RMAN); 542 } else if (s != NULL && (s->r_flags & RF_ALLOCATED) == 0) { 543 /* 544 * Merge previous segment with ours. 545 */ 546 s->r_end = r->r_end; 547 TAILQ_REMOVE(&rm->rm_list, r, r_link); 548 } else if (t != NULL && (t->r_flags & RF_ALLOCATED) == 0) { 549 /* 550 * Merge next segment with ours. 551 */ 552 t->r_start = r->r_start; 553 TAILQ_REMOVE(&rm->rm_list, r, r_link); 554 } else { 555 /* 556 * At this point, we know there is nothing we 557 * can potentially merge with, because on each 558 * side, there is either nothing there or what is 559 * there is still allocated. In that case, we don't 560 * want to remove r from the list; we simply want to 561 * change it to an unallocated region and return 562 * without freeing anything. 563 */ 564 r->r_flags &= ~RF_ALLOCATED; 565 return 0; 566 } 567 568 out: 569 free(r, M_RMAN); 570 return 0; 571 } 572 573 int 574 rman_release_resource(struct resource *r) 575 { 576 int rv; 577 struct rman *rm = r->r_rm; 578 579 mtx_lock(rm->rm_mtx); 580 rv = int_rman_release_resource(rm, r); 581 mtx_unlock(rm->rm_mtx); 582 return (rv); 583 } 584 585 uint32_t 586 rman_make_alignment_flags(uint32_t size) 587 { 588 int i; 589 590 /* 591 * Find the hightest bit set, and add one if more than one bit 592 * set. We're effectively computing the ceil(log2(size)) here. 593 */ 594 for (i = 32; i > 0; i--) 595 if ((1 << i) & size) 596 break; 597 if (~(1 << i) & size) 598 i++; 599 600 return(RF_ALIGNMENT_LOG2(i)); 601 } 602