arch/tile/include/asm/fixmap.h

   1 /*
   2  * Copyright (C) 1998 Ingo Molnar
   3  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   4  *
   5  *   This program is free software; you can redistribute it and/or
   6  *   modify it under the terms of the GNU General Public License
   7  *   as published by the Free Software Foundation, version 2.
   8  *
   9  *   This program is distributed in the hope that it will be useful, but
  10  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  12  *   NON INFRINGEMENT.  See the GNU General Public License for
  13  *   more details.
  14  */
  15
  16 #ifndef _ASM_TILE_FIXMAP_H
  17 #define _ASM_TILE_FIXMAP_H
  18
  19 #include <asm/page.h>
  20
  21 #ifndef __ASSEMBLY__
  22 #include <linux/kernel.h>
  23 #ifdef CONFIG_HIGHMEM
  24 #include <linux/threads.h>
  25 #include <asm/kmap_types.h>
  26 #endif
  27
  28 #define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))
  29 #define __virt_to_fix(x)        ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
  30
  31 /*
  32  * Here we define all the compile-time 'special' virtual
  33  * addresses. The point is to have a constant address at
  34  * compile time, but to set the physical address only
  35  * in the boot process. We allocate these special addresses
  36  * from the end of supervisor virtual memory backwards.
  37  * Also this lets us do fail-safe vmalloc(), we
  38  * can guarantee that these special addresses and
  39  * vmalloc()-ed addresses never overlap.
  40  *
  41  * these 'compile-time allocated' memory buffers are
  42  * fixed-size 4k pages. (or larger if used with an increment
  43  * higher than 1) use fixmap_set(idx,phys) to associate
  44  * physical memory with fixmap indices.
  45  *
  46  * TLB entries of such buffers will not be flushed across
  47  * task switches.
  48  */
  49 enum fixed_addresses {
  50 #ifdef __tilegx__
  51         /*
  52          * TILEPro has unmapped memory above so the hole isn't needed,
  53          * and in any case the hole pushes us over a single 16MB pmd.
  54          */
  55         FIX_HOLE,
  56 #endif
  57 #ifdef CONFIG_HIGHMEM
  58         FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
  59         FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
  60 #endif
  61 #ifdef __tilegx__  /* see homecache.c */
  62         FIX_HOMECACHE_BEGIN,
  63         FIX_HOMECACHE_END = FIX_HOMECACHE_BEGIN+(NR_CPUS)-1,
  64 #endif
  65         __end_of_permanent_fixed_addresses,
  66
  67         /*
  68          * Temporary boot-time mappings, used before ioremap() is functional.
  69          * Not currently needed by the Tile architecture.
  70          */
  71 #define NR_FIX_BTMAPS   0
  72 #if NR_FIX_BTMAPS
  73         FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
  74         FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS - 1,
  75         __end_of_fixed_addresses
  76 #else
  77         __end_of_fixed_addresses = __end_of_permanent_fixed_addresses
  78 #endif
  79 };
  80
  81 #define __FIXADDR_SIZE  (__end_of_permanent_fixed_addresses << PAGE_SHIFT)
  82 #define __FIXADDR_BOOT_SIZE     (__end_of_fixed_addresses << PAGE_SHIFT)
  83 #define FIXADDR_START           (FIXADDR_TOP + PAGE_SIZE - __FIXADDR_SIZE)
  84 #define FIXADDR_BOOT_START      (FIXADDR_TOP + PAGE_SIZE - __FIXADDR_BOOT_SIZE)
  85
  86 extern void __this_fixmap_does_not_exist(void);
  87
  88 /*
  89  * 'index to address' translation. If anyone tries to use the idx
  90  * directly without tranlation, we catch the bug with a NULL-deference
  91  * kernel oops. Illegal ranges of incoming indices are caught too.
  92  */
  93 static __always_inline unsigned long fix_to_virt(const unsigned int idx)
  94 {
  95         /*
  96          * this branch gets completely eliminated after inlining,
  97          * except when someone tries to use fixaddr indices in an
  98          * illegal way. (such as mixing up address types or using
  99          * out-of-range indices).
 100          *
 101          * If it doesn't get removed, the linker will complain
 102          * loudly with a reasonably clear error message..
 103          */
 104         if (idx >= __end_of_fixed_addresses)
 105                 __this_fixmap_does_not_exist();
 106
 107         return __fix_to_virt(idx);
 108 }
 109
 110 static inline unsigned long virt_to_fix(const unsigned long vaddr)
 111 {
 112         BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
 113         return __virt_to_fix(vaddr);
 114 }
 115
 116 #endif /* !__ASSEMBLY__ */
 117
 118 #endif /* _ASM_TILE_FIXMAP_H */