arch/powerpc/include/asm/fixmap.h

   1 /*
   2  * fixmap.h: compile-time virtual memory allocation
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (C) 1998 Ingo Molnar
   9  *
  10  * Copyright 2008 Freescale Semiconductor Inc.
  11  *   Port to powerpc added by Kumar Gala
  12  */
  13
  14 #ifndef _ASM_FIXMAP_H
  15 #define _ASM_FIXMAP_H
  16
  17 #ifndef __ASSEMBLY__
  18 #include <linux/kernel.h>
  19 #include <asm/page.h>
  20 #ifdef CONFIG_HIGHMEM
  21 #include <linux/threads.h>
  22 #include <asm/kmap_types.h>
  23 #endif
  24
  25 #define FIXADDR_TOP     ((unsigned long)(-PAGE_SIZE))
  26
  27 /*
  28  * Here we define all the compile-time 'special' virtual
  29  * addresses. The point is to have a constant address at
  30  * compile time, but to set the physical address only
  31  * in the boot process. We allocate these special addresses
  32  * from the end of virtual memory (0xfffff000) backwards.
  33  * Also this lets us do fail-safe vmalloc(), we
  34  * can guarantee that these special addresses and
  35  * vmalloc()-ed addresses never overlap.
  36  *
  37  * these 'compile-time allocated' memory buffers are
  38  * fixed-size 4k pages. (or larger if used with an increment
  39  * highger than 1) use fixmap_set(idx,phys) to associate
  40  * physical memory with fixmap indices.
  41  *
  42  * TLB entries of such buffers will not be flushed across
  43  * task switches.
  44  */
  45 enum fixed_addresses {
  46         FIX_HOLE,
  47         /* reserve the top 128K for early debugging purposes */
  48         FIX_EARLY_DEBUG_TOP = FIX_HOLE,
  49         FIX_EARLY_DEBUG_BASE = FIX_EARLY_DEBUG_TOP+((128*1024)/PAGE_SIZE)-1,
  50 #ifdef CONFIG_HIGHMEM
  51         FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
  52         FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
  53 #endif
  54         /* FIX_PCIE_MCFG, */
  55         __end_of_fixed_addresses
  56 };
  57
  58 extern void __set_fixmap (enum fixed_addresses idx,
  59                                         phys_addr_t phys, pgprot_t flags);
  60
  61 #define set_fixmap(idx, phys) \
  62                 __set_fixmap(idx, phys, PAGE_KERNEL)
  63 /*
  64  * Some hardware wants to get fixmapped without caching.
  65  */
  66 #define set_fixmap_nocache(idx, phys) \
  67                 __set_fixmap(idx, phys, PAGE_KERNEL_NCG)
  68
  69 #define clear_fixmap(idx) \
  70                 __set_fixmap(idx, 0, __pgprot(0))
  71
  72 #define __FIXADDR_SIZE  (__end_of_fixed_addresses << PAGE_SHIFT)
  73 #define FIXADDR_START           (FIXADDR_TOP - __FIXADDR_SIZE)
  74
  75 #define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))
  76 #define __virt_to_fix(x)        ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
  77
  78 extern void __this_fixmap_does_not_exist(void);
  79
  80 /*
  81  * 'index to address' translation. If anyone tries to use the idx
  82  * directly without tranlation, we catch the bug with a NULL-deference
  83  * kernel oops. Illegal ranges of incoming indices are caught too.
  84  */
  85 static __always_inline unsigned long fix_to_virt(const unsigned int idx)
  86 {
  87         /*
  88          * this branch gets completely eliminated after inlining,
  89          * except when someone tries to use fixaddr indices in an
  90          * illegal way. (such as mixing up address types or using
  91          * out-of-range indices).
  92          *
  93          * If it doesn't get removed, the linker will complain
  94          * loudly with a reasonably clear error message..
  95          */
  96         if (idx >= __end_of_fixed_addresses)
  97                 __this_fixmap_does_not_exist();
  98
  99         return __fix_to_virt(idx);
 100 }
 101
 102 static inline unsigned long virt_to_fix(const unsigned long vaddr)
 103 {
 104         BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
 105         return __virt_to_fix(vaddr);
 106 }
 107
 108 #endif /* !__ASSEMBLY__ */
 109 #endif