kernel/resource.c

   1 /*
   2  *      linux/kernel/resource.c
   3  *
   4  * Copyright (C) 1999   Linus Torvalds
   5  * Copyright (C) 1999   Martin Mares <mj@ucw.cz>
   6  *
   7  * Arbitrary resource management.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/errno.h>
  12 #include <linux/ioport.h>
  13 #include <linux/init.h>
  14 #include <linux/slab.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/fs.h>
  17 #include <linux/proc_fs.h>
  18 #include <linux/sched.h>
  19 #include <linux/seq_file.h>
  20 #include <linux/device.h>
  21 #include <linux/pfn.h>
  22 #include <asm/io.h>
  23
  24
  25 struct resource ioport_resource = {
  26         .name   = "PCI IO",
  27         .start  = 0,
  28         .end    = IO_SPACE_LIMIT,
  29         .flags  = IORESOURCE_IO,
  30 };
  31 EXPORT_SYMBOL(ioport_resource);
  32
  33 struct resource iomem_resource = {
  34         .name   = "PCI mem",
  35         .start  = 0,
  36         .end    = -1,
  37         .flags  = IORESOURCE_MEM,
  38 };
  39 EXPORT_SYMBOL(iomem_resource);
  40
  41 static DEFINE_RWLOCK(resource_lock);
  42
  43 static void *r_next(struct seq_file *m, void *v, loff_t *pos)
  44 {
  45         struct resource *p = v;
  46         (*pos)++;
  47         if (p->child)
  48                 return p->child;
  49         while (!p->sibling && p->parent)
  50                 p = p->parent;
  51         return p->sibling;
  52 }
  53
  54 #ifdef CONFIG_PROC_FS
  55
  56 enum { MAX_IORES_LEVEL = 5 };
  57
  58 static void *r_start(struct seq_file *m, loff_t *pos)
  59         __acquires(resource_lock)
  60 {
  61         struct resource *p = m->private;
  62         loff_t l = 0;
  63         read_lock(&resource_lock);
  64         for (p = p->child; p && l < *pos; p = r_next(m, p, &l))
  65                 ;
  66         return p;
  67 }
  68
  69 static void r_stop(struct seq_file *m, void *v)
  70         __releases(resource_lock)
  71 {
  72         read_unlock(&resource_lock);
  73 }
  74
  75 static int r_show(struct seq_file *m, void *v)
  76 {
  77         struct resource *root = m->private;
  78         struct resource *r = v, *p;
  79         int width = root->end < 0x10000 ? 4 : 8;
  80         int depth;
  81
  82         for (depth = 0, p = r; depth < MAX_IORES_LEVEL; depth++, p = p->parent)
  83                 if (p->parent == root)
  84                         break;
  85         seq_printf(m, "%*s%0*llx-%0*llx : %s\n",
  86                         depth * 2, "",
  87                         width, (unsigned long long) r->start,
  88                         width, (unsigned long long) r->end,
  89                         r->name ? r->name : "<BAD>");
  90         return 0;
  91 }
  92
  93 static const struct seq_operations resource_op = {
  94         .start  = r_start,
  95         .next   = r_next,
  96         .stop   = r_stop,
  97         .show   = r_show,
  98 };
  99
 100 static int ioports_open(struct inode *inode, struct file *file)
 101 {
 102         int res = seq_open(file, &resource_op);
 103         if (!res) {
 104                 struct seq_file *m = file->private_data;
 105                 m->private = &ioport_resource;
 106         }
 107         return res;
 108 }
 109
 110 static int iomem_open(struct inode *inode, struct file *file)
 111 {
 112         int res = seq_open(file, &resource_op);
 113         if (!res) {
 114                 struct seq_file *m = file->private_data;
 115                 m->private = &iomem_resource;
 116         }
 117         return res;
 118 }
 119
 120 static const struct file_operations proc_ioports_operations = {
 121         .open           = ioports_open,
 122         .read           = seq_read,
 123         .llseek         = seq_lseek,
 124         .release        = seq_release,
 125 };
 126
 127 static const struct file_operations proc_iomem_operations = {
 128         .open           = iomem_open,
 129         .read           = seq_read,
 130         .llseek         = seq_lseek,
 131         .release        = seq_release,
 132 };
 133
 134 static int __init ioresources_init(void)
 135 {
 136         proc_create("ioports", 0, NULL, &proc_ioports_operations);
 137         proc_create("iomem", 0, NULL, &proc_iomem_operations);
 138         return 0;
 139 }
 140 __initcall(ioresources_init);
 141
 142 #endif /* CONFIG_PROC_FS */
 143
 144 /* Return the conflict entry if you can't request it */
 145 static struct resource * __request_resource(struct resource *root, struct resource *new)
 146 {
 147         resource_size_t start = new->start;
 148         resource_size_t end = new->end;
 149         struct resource *tmp, **p;
 150
 151         if (end < start)
 152                 return root;
 153         if (start < root->start)
 154                 return root;
 155         if (end > root->end)
 156                 return root;
 157         p = &root->child;
 158         for (;;) {
 159                 tmp = *p;
 160                 if (!tmp || tmp->start > end) {
 161                         new->sibling = tmp;
 162                         *p = new;
 163                         new->parent = root;
 164                         return NULL;
 165                 }
 166                 p = &tmp->sibling;
 167                 if (tmp->end < start)
 168                         continue;
 169                 return tmp;
 170         }
 171 }
 172
 173 static int __release_resource(struct resource *old)
 174 {
 175         struct resource *tmp, **p;
 176
 177         p = &old->parent->child;
 178         for (;;) {
 179                 tmp = *p;
 180                 if (!tmp)
 181                         break;
 182                 if (tmp == old) {
 183                         *p = tmp->sibling;
 184                         old->parent = NULL;
 185                         return 0;
 186                 }
 187                 p = &tmp->sibling;
 188         }
 189         return -EINVAL;
 190 }
 191
 192 static void __release_child_resources(struct resource *r)
 193 {
 194         struct resource *tmp, *p;
 195         resource_size_t size;
 196
 197         p = r->child;
 198         r->child = NULL;
 199         while (p) {
 200                 tmp = p;
 201                 p = p->sibling;
 202
 203                 tmp->parent = NULL;
 204                 tmp->sibling = NULL;
 205                 __release_child_resources(tmp);
 206
 207                 printk(KERN_DEBUG "release child resource %pR\n", tmp);
 208                 /* need to restore size, and keep flags */
 209                 size = resource_size(tmp);
 210                 tmp->start = 0;
 211                 tmp->end = size - 1;
 212         }
 213 }
 214
 215 void release_child_resources(struct resource *r)
 216 {
 217         write_lock(&resource_lock);
 218         __release_child_resources(r);
 219         write_unlock(&resource_lock);
 220 }
 221
 222 /**
 223  * request_resource_conflict - request and reserve an I/O or memory resource
 224  * @root: root resource descriptor
 225  * @new: resource descriptor desired by caller
 226  *
 227  * Returns 0 for success, conflict resource on error.
 228  */
 229 struct resource *request_resource_conflict(struct resource *root, struct resource *new)
 230 {
 231         struct resource *conflict;
 232
 233         write_lock(&resource_lock);
 234         conflict = __request_resource(root, new);
 235         write_unlock(&resource_lock);
 236         return conflict;
 237 }
 238
 239 /**
 240  * request_resource - request and reserve an I/O or memory resource
 241  * @root: root resource descriptor
 242  * @new: resource descriptor desired by caller
 243  *
 244  * Returns 0 for success, negative error code on error.
 245  */
 246 int request_resource(struct resource *root, struct resource *new)
 247 {
 248         struct resource *conflict;
 249
 250         conflict = request_resource_conflict(root, new);
 251         return conflict ? -EBUSY : 0;
 252 }
 253
 254 EXPORT_SYMBOL(request_resource);
 255
 256 /**
 257  * release_resource - release a previously reserved resource
 258  * @old: resource pointer
 259  */
 260 int release_resource(struct resource *old)
 261 {
 262         int retval;
 263
 264         write_lock(&resource_lock);
 265         retval = __release_resource(old);
 266         write_unlock(&resource_lock);
 267         return retval;
 268 }
 269
 270 EXPORT_SYMBOL(release_resource);
 271
 272 #if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
 273 /*
 274  * Finds the lowest memory reosurce exists within [res->start.res->end)
 275  * the caller must specify res->start, res->end, res->flags and "name".
 276  * If found, returns 0, res is overwritten, if not found, returns -1.
 277  */
 278 static int find_next_system_ram(struct resource *res, char *name)
 279 {
 280         resource_size_t start, end;
 281         struct resource *p;
 282
 283         BUG_ON(!res);
 284
 285         start = res->start;
 286         end = res->end;
 287         BUG_ON(start >= end);
 288
 289         read_lock(&resource_lock);
 290         for (p = iomem_resource.child; p ; p = p->sibling) {
 291                 /* system ram is just marked as IORESOURCE_MEM */
 292                 if (p->flags != res->flags)
 293                         continue;
 294                 if (name && strcmp(p->name, name))
 295                         continue;
 296                 if (p->start > end) {
 297                         p = NULL;
 298                         break;
 299                 }
 300                 if ((p->end >= start) && (p->start < end))
 301                         break;
 302         }
 303         read_unlock(&resource_lock);
 304         if (!p)
 305                 return -1;
 306         /* copy data */
 307         if (res->start < p->start)
 308                 res->start = p->start;
 309         if (res->end > p->end)
 310                 res->end = p->end;
 311         return 0;
 312 }
 313
 314 /*
 315  * This function calls callback against all memory range of "System RAM"
 316  * which are marked as IORESOURCE_MEM and IORESOUCE_BUSY.
 317  * Now, this function is only for "System RAM".
 318  */
 319 int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 320                 void *arg, int (*func)(unsigned long, unsigned long, void *))
 321 {
 322         struct resource res;
 323         unsigned long pfn, end_pfn;
 324         u64 orig_end;
 325         int ret = -1;
 326
 327         res.start = (u64) start_pfn << PAGE_SHIFT;
 328         res.end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1;
 329         res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 330         orig_end = res.end;
 331         while ((res.start < res.end) &&
 332                 (find_next_system_ram(&res, "System RAM") >= 0)) {
 333                 pfn = (res.start + PAGE_SIZE - 1) >> PAGE_SHIFT;
 334                 end_pfn = (res.end + 1) >> PAGE_SHIFT;
 335                 if (end_pfn > pfn)
 336                         ret = (*func)(pfn, end_pfn - pfn, arg);
 337                 if (ret)
 338                         break;
 339                 res.start = res.end + 1;
 340                 res.end = orig_end;
 341         }
 342         return ret;
 343 }
 344
 345 #endif
 346
 347 static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
 348 {
 349         return 1;
 350 }
 351 /*
 352  * This generic page_is_ram() returns true if specified address is
 353  * registered as "System RAM" in iomem_resource list.
 354  */
 355 int __weak page_is_ram(unsigned long pfn)
 356 {
 357         return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;
 358 }
 359
 360 static resource_size_t simple_align_resource(void *data,
 361                                              const struct resource *avail,
 362                                              resource_size_t size,
 363                                              resource_size_t align)
 364 {
 365         return avail->start;
 366 }
 367
 368 static void resource_clip(struct resource *res, resource_size_t min,
 369                           resource_size_t max)
 370 {
 371         if (res->start < min)
 372                 res->start = min;
 373         if (res->end > max)
 374                 res->end = max;
 375 }
 376
 377 static bool resource_contains(struct resource *res1, struct resource *res2)
 378 {
 379         return res1->start <= res2->start && res1->end >= res2->end;
 380 }
 381
 382 /*
 383  * Find empty slot in the resource tree given range and alignment.
 384  */
 385 static int find_resource(struct resource *root, struct resource *new,
 386                          resource_size_t size, resource_size_t min,
 387                          resource_size_t max, resource_size_t align,
 388                          resource_size_t (*alignf)(void *,
 389                                                    const struct resource *,
 390                                                    resource_size_t,
 391                                                    resource_size_t),
 392                          void *alignf_data)
 393 {
 394         struct resource *this = root->child;
 395         struct resource tmp = *new, avail, alloc;
 396
 397         tmp.start = root->start;
 398         /*
 399          * Skip past an allocated resource that starts at 0, since the assignment
 400          * of this->start - 1 to tmp->end below would cause an underflow.
 401          */
 402         if (this && this->start == 0) {
 403                 tmp.start = this->end + 1;
 404                 this = this->sibling;
 405         }
 406         for(;;) {
 407                 if (this)
 408                         tmp.end = this->start - 1;
 409                 else
 410                         tmp.end = root->end;
 411
 412                 resource_clip(&tmp, min, max);
 413
 414                 /* Check for overflow after ALIGN() */
 415                 avail = *new;
 416                 avail.start = ALIGN(tmp.start, align);
 417                 avail.end = tmp.end;
 418                 if (avail.start >= tmp.start) {
 419                         alloc.start = alignf(alignf_data, &avail, size, align);
 420                         alloc.end = alloc.start + size - 1;
 421                         if (resource_contains(&avail, &alloc)) {
 422                                 new->start = alloc.start;
 423                                 new->end = alloc.end;
 424                                 return 0;
 425                         }
 426                 }
 427                 if (!this)
 428                         break;
 429                 tmp.start = this->end + 1;
 430                 this = this->sibling;
 431         }
 432         return -EBUSY;
 433 }
 434
 435 /**
 436  * allocate_resource - allocate empty slot in the resource tree given range & alignment
 437  * @root: root resource descriptor
 438  * @new: resource descriptor desired by caller
 439  * @size: requested resource region size
 440  * @min: minimum size to allocate
 441  * @max: maximum size to allocate
 442  * @align: alignment requested, in bytes
 443  * @alignf: alignment function, optional, called if not NULL
 444  * @alignf_data: arbitrary data to pass to the @alignf function
 445  */
 446 int allocate_resource(struct resource *root, struct resource *new,
 447                       resource_size_t size, resource_size_t min,
 448                       resource_size_t max, resource_size_t align,
 449                       resource_size_t (*alignf)(void *,
 450                                                 const struct resource *,
 451                                                 resource_size_t,
 452                                                 resource_size_t),
 453                       void *alignf_data)
 454 {
 455         int err;
 456
 457         if (!alignf)
 458                 alignf = simple_align_resource;
 459
 460         write_lock(&resource_lock);
 461         err = find_resource(root, new, size, min, max, align, alignf, alignf_data);
 462         if (err >= 0 && __request_resource(root, new))
 463                 err = -EBUSY;
 464         write_unlock(&resource_lock);
 465         return err;
 466 }
 467
 468 EXPORT_SYMBOL(allocate_resource);
 469
 470 /*
 471  * Insert a resource into the resource tree. If successful, return NULL,
 472  * otherwise return the conflicting resource (compare to __request_resource())
 473  */
 474 static struct resource * __insert_resource(struct resource *parent, struct resource *new)
 475 {
 476         struct resource *first, *next;
 477
 478         for (;; parent = first) {
 479                 first = __request_resource(parent, new);
 480                 if (!first)
 481                         return first;
 482
 483                 if (first == parent)
 484                         return first;
 485
 486                 if ((first->start > new->start) || (first->end < new->end))
 487                         break;
 488                 if ((first->start == new->start) && (first->end == new->end))
 489                         break;
 490         }
 491
 492         for (next = first; ; next = next->sibling) {
 493                 /* Partial overlap? Bad, and unfixable */
 494                 if (next->start < new->start || next->end > new->end)
 495                         return next;
 496                 if (!next->sibling)
 497                         break;
 498                 if (next->sibling->start > new->end)
 499                         break;
 500         }
 501
 502         new->parent = parent;
 503         new->sibling = next->sibling;
 504         new->child = first;
 505
 506         next->sibling = NULL;
 507         for (next = first; next; next = next->sibling)
 508                 next->parent = new;
 509
 510         if (parent->child == first) {
 511                 parent->child = new;
 512         } else {
 513                 next = parent->child;
 514                 while (next->sibling != first)
 515                         next = next->sibling;
 516                 next->sibling = new;
 517         }
 518         return NULL;
 519 }
 520
 521 /**
 522  * insert_resource_conflict - Inserts resource in the resource tree
 523  * @parent: parent of the new resource
 524  * @new: new resource to insert
 525  *
 526  * Returns 0 on success, conflict resource if the resource can't be inserted.
 527  *
 528  * This function is equivalent to request_resource_conflict when no conflict
 529  * happens. If a conflict happens, and the conflicting resources
 530  * entirely fit within the range of the new resource, then the new
 531  * resource is inserted and the conflicting resources become children of
 532  * the new resource.
 533  */
 534 struct resource *insert_resource_conflict(struct resource *parent, struct resource *new)
 535 {
 536         struct resource *conflict;
 537
 538         write_lock(&resource_lock);
 539         conflict = __insert_resource(parent, new);
 540         write_unlock(&resource_lock);
 541         return conflict;
 542 }
 543
 544 /**
 545  * insert_resource - Inserts a resource in the resource tree
 546  * @parent: parent of the new resource
 547  * @new: new resource to insert
 548  *
 549  * Returns 0 on success, -EBUSY if the resource can't be inserted.
 550  */
 551 int insert_resource(struct resource *parent, struct resource *new)
 552 {
 553         struct resource *conflict;
 554
 555         conflict = insert_resource_conflict(parent, new);
 556         return conflict ? -EBUSY : 0;
 557 }
 558
 559 /**
 560  * insert_resource_expand_to_fit - Insert a resource into the resource tree
 561  * @root: root resource descriptor
 562  * @new: new resource to insert
 563  *
 564  * Insert a resource into the resource tree, possibly expanding it in order
 565  * to make it encompass any conflicting resources.
 566  */
 567 void insert_resource_expand_to_fit(struct resource *root, struct resource *new)
 568 {
 569         if (new->parent)
 570                 return;
 571
 572         write_lock(&resource_lock);
 573         for (;;) {
 574                 struct resource *conflict;
 575
 576                 conflict = __insert_resource(root, new);
 577                 if (!conflict)
 578                         break;
 579                 if (conflict == root)
 580                         break;
 581
 582                 /* Ok, expand resource to cover the conflict, then try again .. */
 583                 if (conflict->start < new->start)
 584                         new->start = conflict->start;
 585                 if (conflict->end > new->end)
 586                         new->end = conflict->end;
 587
 588                 printk("Expanded resource %s due to conflict with %s\n", new->name, conflict->name);
 589         }
 590         write_unlock(&resource_lock);
 591 }
 592
 593 /**
 594  * adjust_resource - modify a resource's start and size
 595  * @res: resource to modify
 596  * @start: new start value
 597  * @size: new size
 598  *
 599  * Given an existing resource, change its start and size to match the
 600  * arguments.  Returns 0 on success, -EBUSY if it can't fit.
 601  * Existing children of the resource are assumed to be immutable.
 602  */
 603 int adjust_resource(struct resource *res, resource_size_t start, resource_size_t size)
 604 {
 605         struct resource *tmp, *parent = res->parent;
 606         resource_size_t end = start + size - 1;
 607         int result = -EBUSY;
 608
 609         write_lock(&resource_lock);
 610
 611         if ((start < parent->start) || (end > parent->end))
 612                 goto out;
 613
 614         for (tmp = res->child; tmp; tmp = tmp->sibling) {
 615                 if ((tmp->start < start) || (tmp->end > end))
 616                         goto out;
 617         }
 618
 619         if (res->sibling && (res->sibling->start <= end))
 620                 goto out;
 621
 622         tmp = parent->child;
 623         if (tmp != res) {
 624                 while (tmp->sibling != res)
 625                         tmp = tmp->sibling;
 626                 if (start <= tmp->end)
 627                         goto out;
 628         }
 629
 630         res->start = start;
 631         res->end = end;
 632         result = 0;
 633
 634  out:
 635         write_unlock(&resource_lock);
 636         return result;
 637 }
 638
 639 static void __init __reserve_region_with_split(struct resource *root,
 640                 resource_size_t start, resource_size_t end,
 641                 const char *name)
 642 {
 643         struct resource *parent = root;
 644         struct resource *conflict;
 645         struct resource *res = kzalloc(sizeof(*res), GFP_ATOMIC);
 646
 647         if (!res)
 648                 return;
 649
 650         res->name = name;
 651         res->start = start;
 652         res->end = end;
 653         res->flags = IORESOURCE_BUSY;
 654
 655         conflict = __request_resource(parent, res);
 656         if (!conflict)
 657                 return;
 658
 659         /* failed, split and try again */
 660         kfree(res);
 661
 662         /* conflict covered whole area */
 663         if (conflict->start <= start && conflict->end >= end)
 664                 return;
 665
 666         if (conflict->start > start)
 667                 __reserve_region_with_split(root, start, conflict->start-1, name);
 668         if (conflict->end < end)
 669                 __reserve_region_with_split(root, conflict->end+1, end, name);
 670 }
 671
 672 void __init reserve_region_with_split(struct resource *root,
 673                 resource_size_t start, resource_size_t end,
 674                 const char *name)
 675 {
 676         write_lock(&resource_lock);
 677         __reserve_region_with_split(root, start, end, name);
 678         write_unlock(&resource_lock);
 679 }
 680
 681 EXPORT_SYMBOL(adjust_resource);
 682
 683 /**
 684  * resource_alignment - calculate resource's alignment
 685  * @res: resource pointer
 686  *
 687  * Returns alignment on success, 0 (invalid alignment) on failure.
 688  */
 689 resource_size_t resource_alignment(struct resource *res)
 690 {
 691         switch (res->flags & (IORESOURCE_SIZEALIGN | IORESOURCE_STARTALIGN)) {
 692         case IORESOURCE_SIZEALIGN:
 693                 return resource_size(res);
 694         case IORESOURCE_STARTALIGN:
 695                 return res->start;
 696         default:
 697                 return 0;
 698         }
 699 }
 700
 701 /*
 702  * This is compatibility stuff for IO resources.
 703  *
 704  * Note how this, unlike the above, knows about
 705  * the IO flag meanings (busy etc).
 706  *
 707  * request_region creates a new busy region.
 708  *
 709  * check_region returns non-zero if the area is already busy.
 710  *
 711  * release_region releases a matching busy region.
 712  */
 713
 714 static DECLARE_WAIT_QUEUE_HEAD(muxed_resource_wait);
 715
 716 /**
 717  * __request_region - create a new busy resource region
 718  * @parent: parent resource descriptor
 719  * @start: resource start address
 720  * @n: resource region size
 721  * @name: reserving caller's ID string
 722  * @flags: IO resource flags
 723  */
 724 struct resource * __request_region(struct resource *parent,
 725                                    resource_size_t start, resource_size_t n,
 726                                    const char *name, int flags)
 727 {
 728         DECLARE_WAITQUEUE(wait, current);
 729         struct resource *res = kzalloc(sizeof(*res), GFP_KERNEL);
 730
 731         if (!res)
 732                 return NULL;
 733
 734         res->name = name;
 735         res->start = start;
 736         res->end = start + n - 1;
 737         res->flags = IORESOURCE_BUSY;
 738         res->flags |= flags;
 739
 740         write_lock(&resource_lock);
 741
 742         for (;;) {
 743                 struct resource *conflict;
 744
 745                 conflict = __request_resource(parent, res);
 746                 if (!conflict)
 747                         break;
 748                 if (conflict != parent) {
 749                         parent = conflict;
 750                         if (!(conflict->flags & IORESOURCE_BUSY))
 751                                 continue;
 752                 }
 753                 if (conflict->flags & flags & IORESOURCE_MUXED) {
 754                         add_wait_queue(&muxed_resource_wait, &wait);
 755                         write_unlock(&resource_lock);
 756                         set_current_state(TASK_UNINTERRUPTIBLE);
 757                         schedule();
 758                         remove_wait_queue(&muxed_resource_wait, &wait);
 759                         write_lock(&resource_lock);
 760                         continue;
 761                 }
 762                 /* Uhhuh, that didn't work out.. */
 763                 kfree(res);
 764                 res = NULL;
 765                 break;
 766         }
 767         write_unlock(&resource_lock);
 768         return res;
 769 }
 770 EXPORT_SYMBOL(__request_region);
 771
 772 /**
 773  * __check_region - check if a resource region is busy or free
 774  * @parent: parent resource descriptor
 775  * @start: resource start address
 776  * @n: resource region size
 777  *
 778  * Returns 0 if the region is free at the moment it is checked,
 779  * returns %-EBUSY if the region is busy.
 780  *
 781  * NOTE:
 782  * This function is deprecated because its use is racy.
 783  * Even if it returns 0, a subsequent call to request_region()
 784  * may fail because another driver etc. just allocated the region.
 785  * Do NOT use it.  It will be removed from the kernel.
 786  */
 787 int __check_region(struct resource *parent, resource_size_t start,
 788                         resource_size_t n)
 789 {
 790         struct resource * res;
 791
 792         res = __request_region(parent, start, n, "check-region", 0);
 793         if (!res)
 794                 return -EBUSY;
 795
 796         release_resource(res);
 797         kfree(res);
 798         return 0;
 799 }
 800 EXPORT_SYMBOL(__check_region);
 801
 802 /**
 803  * __release_region - release a previously reserved resource region
 804  * @parent: parent resource descriptor
 805  * @start: resource start address
 806  * @n: resource region size
 807  *
 808  * The described resource region must match a currently busy region.
 809  */
 810 void __release_region(struct resource *parent, resource_size_t start,
 811                         resource_size_t n)
 812 {
 813         struct resource **p;
 814         resource_size_t end;
 815
 816         p = &parent->child;
 817         end = start + n - 1;
 818
 819         write_lock(&resource_lock);
 820
 821         for (;;) {
 822                 struct resource *res = *p;
 823
 824                 if (!res)
 825                         break;
 826                 if (res->start <= start && res->end >= end) {
 827                         if (!(res->flags & IORESOURCE_BUSY)) {
 828                                 p = &res->child;
 829                                 continue;
 830                         }
 831                         if (res->start != start || res->end != end)
 832                                 break;
 833                         *p = res->sibling;
 834                         write_unlock(&resource_lock);
 835                         if (res->flags & IORESOURCE_MUXED)
 836                                 wake_up(&muxed_resource_wait);
 837                         kfree(res);
 838                         return;
 839                 }
 840                 p = &res->sibling;
 841         }
 842
 843         write_unlock(&resource_lock);
 844
 845         printk(KERN_WARNING "Trying to free nonexistent resource "
 846                 "<%016llx-%016llx>\n", (unsigned long long)start,
 847                 (unsigned long long)end);
 848 }
 849 EXPORT_SYMBOL(__release_region);
 850
 851 /*
 852  * Managed region resource
 853  */
 854 struct region_devres {
 855         struct resource *parent;
 856         resource_size_t start;
 857         resource_size_t n;
 858 };
 859
 860 static void devm_region_release(struct device *dev, void *res)
 861 {
 862         struct region_devres *this = res;
 863
 864         __release_region(this->parent, this->start, this->n);
 865 }
 866
 867 static int devm_region_match(struct device *dev, void *res, void *match_data)
 868 {
 869         struct region_devres *this = res, *match = match_data;
 870
 871         return this->parent == match->parent &&
 872                 this->start == match->start && this->n == match->n;
 873 }
 874
 875 struct resource * __devm_request_region(struct device *dev,
 876                                 struct resource *parent, resource_size_t start,
 877                                 resource_size_t n, const char *name)
 878 {
 879         struct region_devres *dr = NULL;
 880         struct resource *res;
 881
 882         dr = devres_alloc(devm_region_release, sizeof(struct region_devres),
 883                           GFP_KERNEL);
 884         if (!dr)
 885                 return NULL;
 886
 887         dr->parent = parent;
 888         dr->start = start;
 889         dr->n = n;
 890
 891         res = __request_region(parent, start, n, name, 0);
 892         if (res)
 893                 devres_add(dev, dr);
 894         else
 895                 devres_free(dr);
 896
 897         return res;
 898 }
 899 EXPORT_SYMBOL(__devm_request_region);
 900
 901 void __devm_release_region(struct device *dev, struct resource *parent,
 902                            resource_size_t start, resource_size_t n)
 903 {
 904         struct region_devres match_data = { parent, start, n };
 905
 906         __release_region(parent, start, n);
 907         WARN_ON(devres_destroy(dev, devm_region_release, devm_region_match,
 908                                &match_data));
 909 }
 910 EXPORT_SYMBOL(__devm_release_region);
 911
 912 /*
 913  * Called from init/main.c to reserve IO ports.
 914  */
 915 #define MAXRESERVE 4
 916 static int __init reserve_setup(char *str)
 917 {
 918         static int reserved;
 919         static struct resource reserve[MAXRESERVE];
 920
 921         for (;;) {
 922                 unsigned int io_start, io_num;
 923                 int x = reserved;
 924
 925                 if (get_option (&str, &io_start) != 2)
 926                         break;
 927                 if (get_option (&str, &io_num)   == 0)
 928                         break;
 929                 if (x < MAXRESERVE) {
 930                         struct resource *res = reserve + x;
 931                         res->name = "reserved";
 932                         res->start = io_start;
 933                         res->end = io_start + io_num - 1;
 934                         res->flags = IORESOURCE_BUSY;
 935                         res->child = NULL;
 936                         if (request_resource(res->start >= 0x10000 ? &iomem_resource : &ioport_resource, res) == 0)
 937                                 reserved = x+1;
 938                 }
 939         }
 940         return 1;
 941 }
 942
 943 __setup("reserve=", reserve_setup);
 944
 945 /*
 946  * Check if the requested addr and size spans more than any slot in the
 947  * iomem resource tree.
 948  */
 949 int iomem_map_sanity_check(resource_size_t addr, unsigned long size)
 950 {
 951         struct resource *p = &iomem_resource;
 952         int err = 0;
 953         loff_t l;
 954
 955         read_lock(&resource_lock);
 956         for (p = p->child; p ; p = r_next(NULL, p, &l)) {
 957                 /*
 958                  * We can probably skip the resources without
 959                  * IORESOURCE_IO attribute?
 960                  */
 961                 if (p->start >= addr + size)
 962                         continue;
 963                 if (p->end < addr)
 964                         continue;
 965                 if (PFN_DOWN(p->start) <= PFN_DOWN(addr) &&
 966                     PFN_DOWN(p->end) >= PFN_DOWN(addr + size - 1))
 967                         continue;
 968                 /*
 969                  * if a resource is "BUSY", it's not a hardware resource
 970                  * but a driver mapping of such a resource; we don't want
 971                  * to warn for those; some drivers legitimately map only
 972                  * partial hardware resources. (example: vesafb)
 973                  */
 974                 if (p->flags & IORESOURCE_BUSY)
 975                         continue;
 976
 977                 printk(KERN_WARNING "resource map sanity check conflict: "
 978                        "0x%llx 0x%llx 0x%llx 0x%llx %s\n",
 979                        (unsigned long long)addr,
 980                        (unsigned long long)(addr + size - 1),
 981                        (unsigned long long)p->start,
 982                        (unsigned long long)p->end,
 983                        p->name);
 984                 err = -1;
 985                 break;
 986         }
 987         read_unlock(&resource_lock);
 988
 989         return err;
 990 }
 991
 992 #ifdef CONFIG_STRICT_DEVMEM
 993 static int strict_iomem_checks = 1;
 994 #else
 995 static int strict_iomem_checks;
 996 #endif
 997
 998 /*
 999  * check if an address is reserved in the iomem resource tree
1000  * returns 1 if reserved, 0 if not reserved.
1001  */
1002 int iomem_is_exclusive(u64 addr)
1003 {
1004         struct resource *p = &iomem_resource;
1005         int err = 0;
1006         loff_t l;
1007         int size = PAGE_SIZE;
1008
1009         if (!strict_iomem_checks)
1010                 return 0;
1011
1012         addr = addr & PAGE_MASK;
1013
1014         read_lock(&resource_lock);
1015         for (p = p->child; p ; p = r_next(NULL, p, &l)) {
1016                 /*
1017                  * We can probably skip the resources without
1018                  * IORESOURCE_IO attribute?
1019                  */
1020                 if (p->start >= addr + size)
1021                         break;
1022                 if (p->end < addr)
1023                         continue;
1024                 if (p->flags & IORESOURCE_BUSY &&
1025                      p->flags & IORESOURCE_EXCLUSIVE) {
1026                         err = 1;
1027                         break;
1028                 }
1029         }
1030         read_unlock(&resource_lock);
1031
1032         return err;
1033 }
1034
1035 static int __init strict_iomem(char *str)
1036 {
1037         if (strstr(str, "relaxed"))
1038                 strict_iomem_checks = 0;
1039         if (strstr(str, "strict"))
1040                 strict_iomem_checks = 1;
1041         return 1;
1042 }
1043
1044 __setup("iomem=", strict_iomem);