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[linux-3.10.git] / arch / x86 / mm / ioremap.c
1 /*
2  * Re-map IO memory to kernel address space so that we can access it.
3  * This is needed for high PCI addresses that aren't mapped in the
4  * 640k-1MB IO memory area on PC's
5  *
6  * (C) Copyright 1995 1996 Linus Torvalds
7  */
8
9 #include <linux/bootmem.h>
10 #include <linux/init.h>
11 #include <linux/io.h>
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/vmalloc.h>
15 #include <linux/mmiotrace.h>
16
17 #include <asm/cacheflush.h>
18 #include <asm/e820.h>
19 #include <asm/fixmap.h>
20 #include <asm/pgtable.h>
21 #include <asm/tlbflush.h>
22 #include <asm/pgalloc.h>
23 #include <asm/pat.h>
24
25 static inline int phys_addr_valid(resource_size_t addr)
26 {
27 #ifdef CONFIG_PHYS_ADDR_T_64BIT
28         return !(addr >> boot_cpu_data.x86_phys_bits);
29 #else
30         return 1;
31 #endif
32 }
33
34 #ifdef CONFIG_X86_64
35
36 unsigned long __phys_addr(unsigned long x)
37 {
38         if (x >= __START_KERNEL_map) {
39                 x -= __START_KERNEL_map;
40                 VIRTUAL_BUG_ON(x >= KERNEL_IMAGE_SIZE);
41                 x += phys_base;
42         } else {
43                 VIRTUAL_BUG_ON(x < PAGE_OFFSET);
44                 x -= PAGE_OFFSET;
45                 VIRTUAL_BUG_ON(!phys_addr_valid(x));
46         }
47         return x;
48 }
49 EXPORT_SYMBOL(__phys_addr);
50
51 bool __virt_addr_valid(unsigned long x)
52 {
53         if (x >= __START_KERNEL_map) {
54                 x -= __START_KERNEL_map;
55                 if (x >= KERNEL_IMAGE_SIZE)
56                         return false;
57                 x += phys_base;
58         } else {
59                 if (x < PAGE_OFFSET)
60                         return false;
61                 x -= PAGE_OFFSET;
62                 if (!phys_addr_valid(x))
63                         return false;
64         }
65
66         return pfn_valid(x >> PAGE_SHIFT);
67 }
68 EXPORT_SYMBOL(__virt_addr_valid);
69
70 #else
71
72 #ifdef CONFIG_DEBUG_VIRTUAL
73 unsigned long __phys_addr(unsigned long x)
74 {
75         /* VMALLOC_* aren't constants  */
76         VIRTUAL_BUG_ON(x < PAGE_OFFSET);
77         VIRTUAL_BUG_ON(__vmalloc_start_set && is_vmalloc_addr((void *) x));
78         return x - PAGE_OFFSET;
79 }
80 EXPORT_SYMBOL(__phys_addr);
81 #endif
82
83 bool __virt_addr_valid(unsigned long x)
84 {
85         if (x < PAGE_OFFSET)
86                 return false;
87         if (__vmalloc_start_set && is_vmalloc_addr((void *) x))
88                 return false;
89         if (x >= FIXADDR_START)
90                 return false;
91         return pfn_valid((x - PAGE_OFFSET) >> PAGE_SHIFT);
92 }
93 EXPORT_SYMBOL(__virt_addr_valid);
94
95 #endif
96
97 int page_is_ram(unsigned long pagenr)
98 {
99         resource_size_t addr, end;
100         int i;
101
102         /*
103          * A special case is the first 4Kb of memory;
104          * This is a BIOS owned area, not kernel ram, but generally
105          * not listed as such in the E820 table.
106          */
107         if (pagenr == 0)
108                 return 0;
109
110         /*
111          * Second special case: Some BIOSen report the PC BIOS
112          * area (640->1Mb) as ram even though it is not.
113          */
114         if (pagenr >= (BIOS_BEGIN >> PAGE_SHIFT) &&
115                     pagenr < (BIOS_END >> PAGE_SHIFT))
116                 return 0;
117
118         for (i = 0; i < e820.nr_map; i++) {
119                 /*
120                  * Not usable memory:
121                  */
122                 if (e820.map[i].type != E820_RAM)
123                         continue;
124                 addr = (e820.map[i].addr + PAGE_SIZE-1) >> PAGE_SHIFT;
125                 end = (e820.map[i].addr + e820.map[i].size) >> PAGE_SHIFT;
126
127
128                 if ((pagenr >= addr) && (pagenr < end))
129                         return 1;
130         }
131         return 0;
132 }
133
134 /*
135  * Fix up the linear direct mapping of the kernel to avoid cache attribute
136  * conflicts.
137  */
138 int ioremap_change_attr(unsigned long vaddr, unsigned long size,
139                                unsigned long prot_val)
140 {
141         unsigned long nrpages = size >> PAGE_SHIFT;
142         int err;
143
144         switch (prot_val) {
145         case _PAGE_CACHE_UC:
146         default:
147                 err = _set_memory_uc(vaddr, nrpages);
148                 break;
149         case _PAGE_CACHE_WC:
150                 err = _set_memory_wc(vaddr, nrpages);
151                 break;
152         case _PAGE_CACHE_WB:
153                 err = _set_memory_wb(vaddr, nrpages);
154                 break;
155         }
156
157         return err;
158 }
159
160 /*
161  * Remap an arbitrary physical address space into the kernel virtual
162  * address space. Needed when the kernel wants to access high addresses
163  * directly.
164  *
165  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
166  * have to convert them into an offset in a page-aligned mapping, but the
167  * caller shouldn't need to know that small detail.
168  */
169 static void __iomem *__ioremap_caller(resource_size_t phys_addr,
170                 unsigned long size, unsigned long prot_val, void *caller)
171 {
172         unsigned long pfn, offset, vaddr;
173         resource_size_t last_addr;
174         const resource_size_t unaligned_phys_addr = phys_addr;
175         const unsigned long unaligned_size = size;
176         struct vm_struct *area;
177         unsigned long new_prot_val;
178         pgprot_t prot;
179         int retval;
180         void __iomem *ret_addr;
181
182         /* Don't allow wraparound or zero size */
183         last_addr = phys_addr + size - 1;
184         if (!size || last_addr < phys_addr)
185                 return NULL;
186
187         if (!phys_addr_valid(phys_addr)) {
188                 printk(KERN_WARNING "ioremap: invalid physical address %llx\n",
189                        (unsigned long long)phys_addr);
190                 WARN_ON_ONCE(1);
191                 return NULL;
192         }
193
194         /*
195          * Don't remap the low PCI/ISA area, it's always mapped..
196          */
197         if (is_ISA_range(phys_addr, last_addr))
198                 return (__force void __iomem *)phys_to_virt(phys_addr);
199
200         /*
201          * Check if the request spans more than any BAR in the iomem resource
202          * tree.
203          */
204         WARN_ONCE(iomem_map_sanity_check(phys_addr, size),
205                   KERN_INFO "Info: mapping multiple BARs. Your kernel is fine.");
206
207         /*
208          * Don't allow anybody to remap normal RAM that we're using..
209          */
210         for (pfn = phys_addr >> PAGE_SHIFT;
211                                 (pfn << PAGE_SHIFT) < (last_addr & PAGE_MASK);
212                                 pfn++) {
213
214                 int is_ram = page_is_ram(pfn);
215
216                 if (is_ram && pfn_valid(pfn) && !PageReserved(pfn_to_page(pfn)))
217                         return NULL;
218                 WARN_ON_ONCE(is_ram);
219         }
220
221         /*
222          * Mappings have to be page-aligned
223          */
224         offset = phys_addr & ~PAGE_MASK;
225         phys_addr &= PAGE_MASK;
226         size = PAGE_ALIGN(last_addr+1) - phys_addr;
227
228         retval = reserve_memtype(phys_addr, (u64)phys_addr + size,
229                                                 prot_val, &new_prot_val);
230         if (retval) {
231                 pr_debug("Warning: reserve_memtype returned %d\n", retval);
232                 return NULL;
233         }
234
235         if (prot_val != new_prot_val) {
236                 /*
237                  * Do not fallback to certain memory types with certain
238                  * requested type:
239                  * - request is uc-, return cannot be write-back
240                  * - request is uc-, return cannot be write-combine
241                  * - request is write-combine, return cannot be write-back
242                  */
243                 if ((prot_val == _PAGE_CACHE_UC_MINUS &&
244                      (new_prot_val == _PAGE_CACHE_WB ||
245                       new_prot_val == _PAGE_CACHE_WC)) ||
246                     (prot_val == _PAGE_CACHE_WC &&
247                      new_prot_val == _PAGE_CACHE_WB)) {
248                         pr_debug(
249                 "ioremap error for 0x%llx-0x%llx, requested 0x%lx, got 0x%lx\n",
250                                 (unsigned long long)phys_addr,
251                                 (unsigned long long)(phys_addr + size),
252                                 prot_val, new_prot_val);
253                         free_memtype(phys_addr, phys_addr + size);
254                         return NULL;
255                 }
256                 prot_val = new_prot_val;
257         }
258
259         switch (prot_val) {
260         case _PAGE_CACHE_UC:
261         default:
262                 prot = PAGE_KERNEL_IO_NOCACHE;
263                 break;
264         case _PAGE_CACHE_UC_MINUS:
265                 prot = PAGE_KERNEL_IO_UC_MINUS;
266                 break;
267         case _PAGE_CACHE_WC:
268                 prot = PAGE_KERNEL_IO_WC;
269                 break;
270         case _PAGE_CACHE_WB:
271                 prot = PAGE_KERNEL_IO;
272                 break;
273         }
274
275         /*
276          * Ok, go for it..
277          */
278         area = get_vm_area_caller(size, VM_IOREMAP, caller);
279         if (!area)
280                 return NULL;
281         area->phys_addr = phys_addr;
282         vaddr = (unsigned long) area->addr;
283
284         if (kernel_map_sync_memtype(phys_addr, size, prot_val)) {
285                 free_memtype(phys_addr, phys_addr + size);
286                 free_vm_area(area);
287                 return NULL;
288         }
289
290         if (ioremap_page_range(vaddr, vaddr + size, phys_addr, prot)) {
291                 free_memtype(phys_addr, phys_addr + size);
292                 free_vm_area(area);
293                 return NULL;
294         }
295
296         ret_addr = (void __iomem *) (vaddr + offset);
297         mmiotrace_ioremap(unaligned_phys_addr, unaligned_size, ret_addr);
298
299         return ret_addr;
300 }
301
302 /**
303  * ioremap_nocache     -   map bus memory into CPU space
304  * @offset:    bus address of the memory
305  * @size:      size of the resource to map
306  *
307  * ioremap_nocache performs a platform specific sequence of operations to
308  * make bus memory CPU accessible via the readb/readw/readl/writeb/
309  * writew/writel functions and the other mmio helpers. The returned
310  * address is not guaranteed to be usable directly as a virtual
311  * address.
312  *
313  * This version of ioremap ensures that the memory is marked uncachable
314  * on the CPU as well as honouring existing caching rules from things like
315  * the PCI bus. Note that there are other caches and buffers on many
316  * busses. In particular driver authors should read up on PCI writes
317  *
318  * It's useful if some control registers are in such an area and
319  * write combining or read caching is not desirable:
320  *
321  * Must be freed with iounmap.
322  */
323 void __iomem *ioremap_nocache(resource_size_t phys_addr, unsigned long size)
324 {
325         /*
326          * Ideally, this should be:
327          *      pat_enabled ? _PAGE_CACHE_UC : _PAGE_CACHE_UC_MINUS;
328          *
329          * Till we fix all X drivers to use ioremap_wc(), we will use
330          * UC MINUS.
331          */
332         unsigned long val = _PAGE_CACHE_UC_MINUS;
333
334         return __ioremap_caller(phys_addr, size, val,
335                                 __builtin_return_address(0));
336 }
337 EXPORT_SYMBOL(ioremap_nocache);
338
339 /**
340  * ioremap_wc   -       map memory into CPU space write combined
341  * @offset:     bus address of the memory
342  * @size:       size of the resource to map
343  *
344  * This version of ioremap ensures that the memory is marked write combining.
345  * Write combining allows faster writes to some hardware devices.
346  *
347  * Must be freed with iounmap.
348  */
349 void __iomem *ioremap_wc(resource_size_t phys_addr, unsigned long size)
350 {
351         if (pat_enabled)
352                 return __ioremap_caller(phys_addr, size, _PAGE_CACHE_WC,
353                                         __builtin_return_address(0));
354         else
355                 return ioremap_nocache(phys_addr, size);
356 }
357 EXPORT_SYMBOL(ioremap_wc);
358
359 void __iomem *ioremap_cache(resource_size_t phys_addr, unsigned long size)
360 {
361         return __ioremap_caller(phys_addr, size, _PAGE_CACHE_WB,
362                                 __builtin_return_address(0));
363 }
364 EXPORT_SYMBOL(ioremap_cache);
365
366 static void __iomem *ioremap_default(resource_size_t phys_addr,
367                                         unsigned long size)
368 {
369         unsigned long flags;
370         void __iomem *ret;
371         int err;
372
373         /*
374          * - WB for WB-able memory and no other conflicting mappings
375          * - UC_MINUS for non-WB-able memory with no other conflicting mappings
376          * - Inherit from confliting mappings otherwise
377          */
378         err = reserve_memtype(phys_addr, phys_addr + size,
379                                 _PAGE_CACHE_WB, &flags);
380         if (err < 0)
381                 return NULL;
382
383         ret = __ioremap_caller(phys_addr, size, flags,
384                                __builtin_return_address(0));
385
386         free_memtype(phys_addr, phys_addr + size);
387         return ret;
388 }
389
390 void __iomem *ioremap_prot(resource_size_t phys_addr, unsigned long size,
391                                 unsigned long prot_val)
392 {
393         return __ioremap_caller(phys_addr, size, (prot_val & _PAGE_CACHE_MASK),
394                                 __builtin_return_address(0));
395 }
396 EXPORT_SYMBOL(ioremap_prot);
397
398 /**
399  * iounmap - Free a IO remapping
400  * @addr: virtual address from ioremap_*
401  *
402  * Caller must ensure there is only one unmapping for the same pointer.
403  */
404 void iounmap(volatile void __iomem *addr)
405 {
406         struct vm_struct *p, *o;
407
408         if ((void __force *)addr <= high_memory)
409                 return;
410
411         /*
412          * __ioremap special-cases the PCI/ISA range by not instantiating a
413          * vm_area and by simply returning an address into the kernel mapping
414          * of ISA space.   So handle that here.
415          */
416         if ((void __force *)addr >= phys_to_virt(ISA_START_ADDRESS) &&
417             (void __force *)addr < phys_to_virt(ISA_END_ADDRESS))
418                 return;
419
420         addr = (volatile void __iomem *)
421                 (PAGE_MASK & (unsigned long __force)addr);
422
423         mmiotrace_iounmap(addr);
424
425         /* Use the vm area unlocked, assuming the caller
426            ensures there isn't another iounmap for the same address
427            in parallel. Reuse of the virtual address is prevented by
428            leaving it in the global lists until we're done with it.
429            cpa takes care of the direct mappings. */
430         read_lock(&vmlist_lock);
431         for (p = vmlist; p; p = p->next) {
432                 if (p->addr == (void __force *)addr)
433                         break;
434         }
435         read_unlock(&vmlist_lock);
436
437         if (!p) {
438                 printk(KERN_ERR "iounmap: bad address %p\n", addr);
439                 dump_stack();
440                 return;
441         }
442
443         free_memtype(p->phys_addr, p->phys_addr + get_vm_area_size(p));
444
445         /* Finally remove it */
446         o = remove_vm_area((void __force *)addr);
447         BUG_ON(p != o || o == NULL);
448         kfree(p);
449 }
450 EXPORT_SYMBOL(iounmap);
451
452 /*
453  * Convert a physical pointer to a virtual kernel pointer for /dev/mem
454  * access
455  */
456 void *xlate_dev_mem_ptr(unsigned long phys)
457 {
458         void *addr;
459         unsigned long start = phys & PAGE_MASK;
460
461         /* If page is RAM, we can use __va. Otherwise ioremap and unmap. */
462         if (page_is_ram(start >> PAGE_SHIFT))
463                 return __va(phys);
464
465         addr = (void __force *)ioremap_default(start, PAGE_SIZE);
466         if (addr)
467                 addr = (void *)((unsigned long)addr | (phys & ~PAGE_MASK));
468
469         return addr;
470 }
471
472 void unxlate_dev_mem_ptr(unsigned long phys, void *addr)
473 {
474         if (page_is_ram(phys >> PAGE_SHIFT))
475                 return;
476
477         iounmap((void __iomem *)((unsigned long)addr & PAGE_MASK));
478         return;
479 }
480
481 static int __initdata early_ioremap_debug;
482
483 static int __init early_ioremap_debug_setup(char *str)
484 {
485         early_ioremap_debug = 1;
486
487         return 0;
488 }
489 early_param("early_ioremap_debug", early_ioremap_debug_setup);
490
491 static __initdata int after_paging_init;
492 static pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)] __page_aligned_bss;
493
494 static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
495 {
496         /* Don't assume we're using swapper_pg_dir at this point */
497         pgd_t *base = __va(read_cr3());
498         pgd_t *pgd = &base[pgd_index(addr)];
499         pud_t *pud = pud_offset(pgd, addr);
500         pmd_t *pmd = pmd_offset(pud, addr);
501
502         return pmd;
503 }
504
505 static inline pte_t * __init early_ioremap_pte(unsigned long addr)
506 {
507         return &bm_pte[pte_index(addr)];
508 }
509
510 static unsigned long slot_virt[FIX_BTMAPS_SLOTS] __initdata;
511
512 void __init early_ioremap_init(void)
513 {
514         pmd_t *pmd;
515         int i;
516
517         if (early_ioremap_debug)
518                 printk(KERN_INFO "early_ioremap_init()\n");
519
520         for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
521                 slot_virt[i] = __fix_to_virt(FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*i);
522
523         pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
524         memset(bm_pte, 0, sizeof(bm_pte));
525         pmd_populate_kernel(&init_mm, pmd, bm_pte);
526
527         /*
528          * The boot-ioremap range spans multiple pmds, for which
529          * we are not prepared:
530          */
531         if (pmd != early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END))) {
532                 WARN_ON(1);
533                 printk(KERN_WARNING "pmd %p != %p\n",
534                        pmd, early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END)));
535                 printk(KERN_WARNING "fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
536                         fix_to_virt(FIX_BTMAP_BEGIN));
537                 printk(KERN_WARNING "fix_to_virt(FIX_BTMAP_END):   %08lx\n",
538                         fix_to_virt(FIX_BTMAP_END));
539
540                 printk(KERN_WARNING "FIX_BTMAP_END:       %d\n", FIX_BTMAP_END);
541                 printk(KERN_WARNING "FIX_BTMAP_BEGIN:     %d\n",
542                        FIX_BTMAP_BEGIN);
543         }
544 }
545
546 void __init early_ioremap_reset(void)
547 {
548         after_paging_init = 1;
549 }
550
551 static void __init __early_set_fixmap(enum fixed_addresses idx,
552                                    unsigned long phys, pgprot_t flags)
553 {
554         unsigned long addr = __fix_to_virt(idx);
555         pte_t *pte;
556
557         if (idx >= __end_of_fixed_addresses) {
558                 BUG();
559                 return;
560         }
561         pte = early_ioremap_pte(addr);
562
563         if (pgprot_val(flags))
564                 set_pte(pte, pfn_pte(phys >> PAGE_SHIFT, flags));
565         else
566                 pte_clear(&init_mm, addr, pte);
567         __flush_tlb_one(addr);
568 }
569
570 static inline void __init early_set_fixmap(enum fixed_addresses idx,
571                                            unsigned long phys, pgprot_t prot)
572 {
573         if (after_paging_init)
574                 __set_fixmap(idx, phys, prot);
575         else
576                 __early_set_fixmap(idx, phys, prot);
577 }
578
579 static inline void __init early_clear_fixmap(enum fixed_addresses idx)
580 {
581         if (after_paging_init)
582                 clear_fixmap(idx);
583         else
584                 __early_set_fixmap(idx, 0, __pgprot(0));
585 }
586
587 static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
588 static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
589
590 static int __init check_early_ioremap_leak(void)
591 {
592         int count = 0;
593         int i;
594
595         for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
596                 if (prev_map[i])
597                         count++;
598
599         if (!count)
600                 return 0;
601         WARN(1, KERN_WARNING
602                "Debug warning: early ioremap leak of %d areas detected.\n",
603                 count);
604         printk(KERN_WARNING
605                 "please boot with early_ioremap_debug and report the dmesg.\n");
606
607         return 1;
608 }
609 late_initcall(check_early_ioremap_leak);
610
611 static void __init __iomem *
612 __early_ioremap(unsigned long phys_addr, unsigned long size, pgprot_t prot)
613 {
614         unsigned long offset, last_addr;
615         unsigned int nrpages;
616         enum fixed_addresses idx0, idx;
617         int i, slot;
618
619         WARN_ON(system_state != SYSTEM_BOOTING);
620
621         slot = -1;
622         for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
623                 if (!prev_map[i]) {
624                         slot = i;
625                         break;
626                 }
627         }
628
629         if (slot < 0) {
630                 printk(KERN_INFO "early_iomap(%08lx, %08lx) not found slot\n",
631                          phys_addr, size);
632                 WARN_ON(1);
633                 return NULL;
634         }
635
636         if (early_ioremap_debug) {
637                 printk(KERN_INFO "early_ioremap(%08lx, %08lx) [%d] => ",
638                        phys_addr, size, slot);
639                 dump_stack();
640         }
641
642         /* Don't allow wraparound or zero size */
643         last_addr = phys_addr + size - 1;
644         if (!size || last_addr < phys_addr) {
645                 WARN_ON(1);
646                 return NULL;
647         }
648
649         prev_size[slot] = size;
650         /*
651          * Mappings have to be page-aligned
652          */
653         offset = phys_addr & ~PAGE_MASK;
654         phys_addr &= PAGE_MASK;
655         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
656
657         /*
658          * Mappings have to fit in the FIX_BTMAP area.
659          */
660         nrpages = size >> PAGE_SHIFT;
661         if (nrpages > NR_FIX_BTMAPS) {
662                 WARN_ON(1);
663                 return NULL;
664         }
665
666         /*
667          * Ok, go for it..
668          */
669         idx0 = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
670         idx = idx0;
671         while (nrpages > 0) {
672                 early_set_fixmap(idx, phys_addr, prot);
673                 phys_addr += PAGE_SIZE;
674                 --idx;
675                 --nrpages;
676         }
677         if (early_ioremap_debug)
678                 printk(KERN_CONT "%08lx + %08lx\n", offset, slot_virt[slot]);
679
680         prev_map[slot] = (void __iomem *)(offset + slot_virt[slot]);
681         return prev_map[slot];
682 }
683
684 /* Remap an IO device */
685 void __init __iomem *early_ioremap(unsigned long phys_addr, unsigned long size)
686 {
687         return __early_ioremap(phys_addr, size, PAGE_KERNEL_IO);
688 }
689
690 /* Remap memory */
691 void __init __iomem *early_memremap(unsigned long phys_addr, unsigned long size)
692 {
693         return __early_ioremap(phys_addr, size, PAGE_KERNEL);
694 }
695
696 void __init early_iounmap(void __iomem *addr, unsigned long size)
697 {
698         unsigned long virt_addr;
699         unsigned long offset;
700         unsigned int nrpages;
701         enum fixed_addresses idx;
702         int i, slot;
703
704         slot = -1;
705         for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
706                 if (prev_map[i] == addr) {
707                         slot = i;
708                         break;
709                 }
710         }
711
712         if (slot < 0) {
713                 printk(KERN_INFO "early_iounmap(%p, %08lx) not found slot\n",
714                          addr, size);
715                 WARN_ON(1);
716                 return;
717         }
718
719         if (prev_size[slot] != size) {
720                 printk(KERN_INFO "early_iounmap(%p, %08lx) [%d] size not consistent %08lx\n",
721                          addr, size, slot, prev_size[slot]);
722                 WARN_ON(1);
723                 return;
724         }
725
726         if (early_ioremap_debug) {
727                 printk(KERN_INFO "early_iounmap(%p, %08lx) [%d]\n", addr,
728                        size, slot);
729                 dump_stack();
730         }
731
732         virt_addr = (unsigned long)addr;
733         if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN)) {
734                 WARN_ON(1);
735                 return;
736         }
737         offset = virt_addr & ~PAGE_MASK;
738         nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;
739
740         idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
741         while (nrpages > 0) {
742                 early_clear_fixmap(idx);
743                 --idx;
744                 --nrpages;
745         }
746         prev_map[slot] = NULL;
747 }