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/bus.h> /* XXX debugging */ 66 #include <machine/bus.h> 67 #include <sys/rman.h> 68 69 #ifdef RMAN_DEBUG 70 #define DPRINTF(params) printf##params 71 #else 72 #define DPRINTF(params) 73 #endif 74 75 static MALLOC_DEFINE(M_RMAN, "rman", "Resource manager"); 76 77 struct rman_head rman_head; 78 #ifndef NULL_SIMPLELOCKS 79 static struct simplelock rman_lock; /* mutex to protect rman_head */ 80 #endif 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); 85 86 #define CIRCLEQ_TERMCOND(var, head) (var == (void *)&(head)) 87 88 int 89 rman_init(struct rman *rm) 90 { 91 static int once; 92 93 if (once == 0) { 94 once = 1; 95 TAILQ_INIT(&rman_head); 96 simple_lock_init(&rman_lock); 97 } 98 99 if (rm->rm_type == RMAN_UNINIT) 100 panic("rman_init"); 101 if (rm->rm_type == RMAN_GAUGE) 102 panic("implement RMAN_GAUGE"); 103 104 CIRCLEQ_INIT(&rm->rm_list); 105 rm->rm_slock = malloc(sizeof *rm->rm_slock, M_RMAN, M_NOWAIT); 106 if (rm->rm_slock == 0) 107 return ENOMEM; 108 simple_lock_init(rm->rm_slock); 109 110 simple_lock(&rman_lock); 111 TAILQ_INSERT_TAIL(&rman_head, rm, rm_link); 112 simple_unlock(&rman_lock); 113 return 0; 114 } 115 116 /* 117 * NB: this interface is not robust against programming errors which 118 * add multiple copies of the same region. 119 */ 120 int 121 rman_manage_region(struct rman *rm, u_long start, u_long end) 122 { 123 struct resource *r, *s; 124 125 r = malloc(sizeof *r, M_RMAN, M_NOWAIT); 126 if (r == 0) 127 return ENOMEM; 128 bzero(r, sizeof *r); 129 r->r_sharehead = 0; 130 r->r_start = start; 131 r->r_end = end; 132 r->r_flags = 0; 133 r->r_dev = 0; 134 r->r_rm = rm; 135 136 simple_lock(rm->rm_slock); 137 for (s = CIRCLEQ_FIRST(&rm->rm_list); 138 !CIRCLEQ_TERMCOND(s, rm->rm_list) && s->r_end < r->r_start; 139 s = CIRCLEQ_NEXT(s, r_link)) 140 ; 141 142 if (CIRCLEQ_TERMCOND(s, rm->rm_list)) { 143 CIRCLEQ_INSERT_TAIL(&rm->rm_list, r, r_link); 144 } else { 145 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, r, r_link); 146 } 147 148 simple_unlock(rm->rm_slock); 149 return 0; 150 } 151 152 int 153 rman_fini(struct rman *rm) 154 { 155 struct resource *r; 156 157 simple_lock(rm->rm_slock); 158 CIRCLEQ_FOREACH(r, &rm->rm_list, r_link) { 159 if (r->r_flags & RF_ALLOCATED) { 160 simple_unlock(rm->rm_slock); 161 return EBUSY; 162 } 163 } 164 165 /* 166 * There really should only be one of these if we are in this 167 * state and the code is working properly, but it can't hurt. 168 */ 169 while (!CIRCLEQ_EMPTY(&rm->rm_list)) { 170 r = CIRCLEQ_FIRST(&rm->rm_list); 171 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link); 172 free(r, M_RMAN); 173 } 174 simple_unlock(rm->rm_slock); 175 simple_lock(&rman_lock); 176 TAILQ_REMOVE(&rman_head, rm, rm_link); 177 simple_unlock(&rman_lock); 178 free(rm->rm_slock, M_RMAN); 179 180 return 0; 181 } 182 183 struct resource * 184 rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count, 185 u_int flags, struct device *dev) 186 { 187 u_int want_activate; 188 struct resource *r, *s, *rv; 189 u_long rstart, rend; 190 191 rv = 0; 192 193 DPRINTF(("rman_reserve_resource: <%s> request: [%#lx, %#lx], length " 194 "%#lx, flags %u, device %s%d\n", rm->rm_descr, start, end, 195 count, flags, device_get_name(dev), device_get_unit(dev))); 196 want_activate = (flags & RF_ACTIVE); 197 flags &= ~RF_ACTIVE; 198 199 simple_lock(rm->rm_slock); 200 201 for (r = CIRCLEQ_FIRST(&rm->rm_list); 202 !CIRCLEQ_TERMCOND(r, rm->rm_list) && r->r_end < start; 203 r = CIRCLEQ_NEXT(r, r_link)) 204 ; 205 206 if (CIRCLEQ_TERMCOND(r, rm->rm_list)) { 207 DPRINTF(("could not find a region\n")); 208 goto out; 209 } 210 211 /* 212 * First try to find an acceptable totally-unshared region. 213 */ 214 for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list); 215 s = CIRCLEQ_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", s->r_start, end)); 219 break; 220 } 221 if (s->r_flags & RF_ALLOCATED) { 222 DPRINTF(("region is allocated\n")); 223 continue; 224 } 225 rstart = max(s->r_start, start); 226 rend = min(s->r_end, max(start + count, end)); 227 DPRINTF(("truncated region: [%#lx, %#lx]; size %#lx (requested %#lx)\n", 228 rstart, rend, (rend - rstart + 1), count)); 229 230 if ((rend - rstart + 1) >= count) { 231 DPRINTF(("candidate region: [%#lx, %#lx], size %#lx\n", 232 rend, rstart, (rend - rstart + 1))); 233 if ((s->r_end - s->r_start + 1) == count) { 234 DPRINTF(("candidate region is entire chunk\n")); 235 rv = s; 236 rv->r_flags |= RF_ALLOCATED | flags; 237 rv->r_dev = dev; 238 goto out; 239 } 240 241 /* 242 * If s->r_start < rstart and 243 * s->r_end > rstart + count - 1, then 244 * we need to split the region into three pieces 245 * (the middle one will get returned to the user). 246 * Otherwise, we are allocating at either the 247 * beginning or the end of s, so we only need to 248 * split it in two. The first case requires 249 * two new allocations; the second requires but one. 250 */ 251 rv = malloc(sizeof *rv, M_RMAN, M_NOWAIT); 252 if (rv == 0) 253 goto out; 254 bzero(rv, sizeof *rv); 255 rv->r_start = rstart; 256 rv->r_end = rstart + count - 1; 257 rv->r_flags = flags | RF_ALLOCATED; 258 rv->r_dev = dev; 259 rv->r_sharehead = 0; 260 rv->r_rm = rm; 261 262 if (s->r_start < rv->r_start && s->r_end > rv->r_end) { 263 DPRINTF(("splitting region in three parts: " 264 "[%#lx, %#lx]; [%#lx, %#lx]; [%#lx, %#lx]\n", 265 s->r_start, rv->r_start - 1, 266 rv->r_start, rv->r_end, 267 rv->r_end + 1, s->r_end)); 268 /* 269 * We are allocating in the middle. 270 */ 271 r = malloc(sizeof *r, M_RMAN, M_NOWAIT); 272 if (r == 0) { 273 free(rv, M_RMAN); 274 rv = 0; 275 goto out; 276 } 277 bzero(r, sizeof *r); 278 r->r_start = rv->r_end + 1; 279 r->r_end = s->r_end; 280 r->r_flags = s->r_flags; 281 r->r_dev = 0; 282 r->r_sharehead = 0; 283 r->r_rm = rm; 284 s->r_end = rv->r_start - 1; 285 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv, 286 r_link); 287 CIRCLEQ_INSERT_AFTER(&rm->rm_list, rv, r, 288 r_link); 289 } else if (s->r_start == rv->r_start) { 290 DPRINTF(("allocating from the beginning\n")); 291 /* 292 * We are allocating at the beginning. 293 */ 294 s->r_start = rv->r_end + 1; 295 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, s, rv, 296 r_link); 297 } else { 298 DPRINTF(("allocating at the end\n")); 299 /* 300 * We are allocating at the end. 301 */ 302 s->r_end = rv->r_start - 1; 303 CIRCLEQ_INSERT_AFTER(&rm->rm_list, s, rv, 304 r_link); 305 } 306 goto out; 307 } 308 } 309 310 /* 311 * Now find an acceptable shared region, if the client's requirements 312 * allow sharing. By our implementation restriction, a candidate 313 * region must match exactly by both size and sharing type in order 314 * to be considered compatible with the client's request. (The 315 * former restriction could probably be lifted without too much 316 * additional work, but this does not seem warranted.) 317 */ 318 DPRINTF(("no unshared regions found\n")); 319 if ((flags & (RF_SHAREABLE | RF_TIMESHARE)) == 0) 320 goto out; 321 322 for (s = r; !CIRCLEQ_TERMCOND(s, rm->rm_list); 323 s = CIRCLEQ_NEXT(s, r_link)) { 324 if (s->r_start > end) 325 break; 326 if ((s->r_flags & flags) != flags) 327 continue; 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 = malloc(sizeof *rv, M_RMAN, M_NOWAIT); 333 if (rv == 0) 334 goto out; 335 bzero(rv, sizeof *rv); 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); 340 rv->r_dev = dev; 341 rv->r_rm = rm; 342 if (s->r_sharehead == 0) { 343 s->r_sharehead = malloc(sizeof *s->r_sharehead, 344 M_RMAN, M_NOWAIT); 345 if (s->r_sharehead == 0) { 346 free(rv, M_RMAN); 347 rv = 0; 348 goto out; 349 } 350 bzero(s->r_sharehead, sizeof *s->r_sharehead); 351 LIST_INIT(s->r_sharehead); 352 LIST_INSERT_HEAD(s->r_sharehead, s, 353 r_sharelink); 354 s->r_flags |= RF_FIRSTSHARE; 355 } 356 rv->r_sharehead = s->r_sharehead; 357 LIST_INSERT_HEAD(s->r_sharehead, rv, r_sharelink); 358 goto out; 359 } 360 } 361 362 /* 363 * We couldn't find anything. 364 */ 365 out: 366 /* 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.) 372 */ 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); 377 rv = 0; 378 } 379 } 380 381 simple_unlock(rm->rm_slock); 382 return (rv); 383 } 384 385 static int 386 int_rman_activate_resource(struct rman *rm, struct resource *r, 387 struct resource **whohas) 388 { 389 struct resource *s; 390 int ok; 391 392 /* 393 * If we are not timesharing, then there is nothing much to do. 394 * If we already have the resource, then there is nothing at all to do. 395 * If we are not on a sharing list with anybody else, then there is 396 * little to do. 397 */ 398 if ((r->r_flags & RF_TIMESHARE) == 0 399 || (r->r_flags & RF_ACTIVE) != 0 400 || r->r_sharehead == 0) { 401 r->r_flags |= RF_ACTIVE; 402 return 0; 403 } 404 405 ok = 1; 406 for (s = LIST_FIRST(r->r_sharehead); s && ok; 407 s = LIST_NEXT(s, r_sharelink)) { 408 if ((s->r_flags & RF_ACTIVE) != 0) { 409 ok = 0; 410 *whohas = s; 411 } 412 } 413 if (ok) { 414 r->r_flags |= RF_ACTIVE; 415 return 0; 416 } 417 return EBUSY; 418 } 419 420 int 421 rman_activate_resource(struct resource *r) 422 { 423 int rv; 424 struct resource *whohas; 425 struct rman *rm; 426 427 rm = r->r_rm; 428 simple_lock(rm->rm_slock); 429 rv = int_rman_activate_resource(rm, r, &whohas); 430 simple_unlock(rm->rm_slock); 431 return rv; 432 } 433 434 int 435 rman_await_resource(struct resource *r, int pri, int timo) 436 { 437 int rv, s; 438 struct resource *whohas; 439 struct rman *rm; 440 441 rm = r->r_rm; 442 for (;;) { 443 simple_lock(rm->rm_slock); 444 rv = int_rman_activate_resource(rm, r, &whohas); 445 if (rv != EBUSY) 446 return (rv); /* returns with simplelock */ 447 448 if (r->r_sharehead == 0) 449 panic("rman_await_resource"); 450 /* 451 * splhigh hopefully will prevent a race between 452 * simple_unlock and tsleep where a process 453 * could conceivably get in and release the resource 454 * before we have a chance to sleep on it. 455 */ 456 s = splhigh(); 457 whohas->r_flags |= RF_WANTED; 458 simple_unlock(rm->rm_slock); 459 rv = tsleep(r->r_sharehead, pri, "rmwait", timo); 460 if (rv) { 461 splx(s); 462 return rv; 463 } 464 simple_lock(rm->rm_slock); 465 splx(s); 466 } 467 } 468 469 static int 470 int_rman_deactivate_resource(struct resource *r) 471 { 472 struct rman *rm; 473 474 rm = r->r_rm; 475 r->r_flags &= ~RF_ACTIVE; 476 if (r->r_flags & RF_WANTED) { 477 r->r_flags &= ~RF_WANTED; 478 wakeup(r->r_sharehead); 479 } 480 return 0; 481 } 482 483 int 484 rman_deactivate_resource(struct resource *r) 485 { 486 struct rman *rm; 487 488 rm = r->r_rm; 489 simple_lock(rm->rm_slock); 490 int_rman_deactivate_resource(r); 491 simple_unlock(rm->rm_slock); 492 return 0; 493 } 494 495 static int 496 int_rman_release_resource(struct rman *rm, struct resource *r) 497 { 498 struct resource *s, *t; 499 500 if (r->r_flags & RF_ACTIVE) 501 int_rman_deactivate_resource(r); 502 503 /* 504 * Check for a sharing list first. If there is one, then we don't 505 * have to think as hard. 506 */ 507 if (r->r_sharehead) { 508 /* 509 * If a sharing list exists, then we know there are at 510 * least two sharers. 511 * 512 * If we are in the main circleq, appoint someone else. 513 */ 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 CIRCLEQ_INSERT_BEFORE(&rm->rm_list, r, s, r_link); 519 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link); 520 } 521 522 /* 523 * Make sure that the sharing list goes away completely 524 * if the resource is no longer being shared at all. 525 */ 526 if (LIST_NEXT(s, r_sharelink) == 0) { 527 free(s->r_sharehead, M_RMAN); 528 s->r_sharehead = 0; 529 s->r_flags &= ~RF_FIRSTSHARE; 530 } 531 goto out; 532 } 533 534 /* 535 * Look at the adjacent resources in the list and see if our 536 * segment can be merged with any of them. 537 */ 538 s = CIRCLEQ_PREV(r, r_link); 539 t = CIRCLEQ_NEXT(r, r_link); 540 541 if (s != (void *)&rm->rm_list && (s->r_flags & RF_ALLOCATED) == 0 542 && t != (void *)&rm->rm_list && (t->r_flags & RF_ALLOCATED) == 0) { 543 /* 544 * Merge all three segments. 545 */ 546 s->r_end = t->r_end; 547 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link); 548 CIRCLEQ_REMOVE(&rm->rm_list, t, r_link); 549 free(t, M_RMAN); 550 } else if (s != (void *)&rm->rm_list 551 && (s->r_flags & RF_ALLOCATED) == 0) { 552 /* 553 * Merge previous segment with ours. 554 */ 555 s->r_end = r->r_end; 556 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link); 557 } else if (t != (void *)&rm->rm_list 558 && (t->r_flags & RF_ALLOCATED) == 0) { 559 /* 560 * Merge next segment with ours. 561 */ 562 t->r_start = r->r_start; 563 CIRCLEQ_REMOVE(&rm->rm_list, r, r_link); 564 } else { 565 /* 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. 573 */ 574 r->r_flags &= ~RF_ALLOCATED; 575 return 0; 576 } 577 578 out: 579 free(r, M_RMAN); 580 return 0; 581 } 582 583 int 584 rman_release_resource(struct resource *r) 585 { 586 int rv; 587 struct rman *rm = r->r_rm; 588 589 simple_lock(rm->rm_slock); 590 rv = int_rman_release_resource(rm, r); 591 simple_unlock(rm->rm_slock); 592 return (rv); 593 } 594