LXR linux/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 */
  45enum fixed_addresses {
  46        FIX_HOLE,
  47#ifdef CONFIG_HIGHMEM
  48        FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
  49        FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
  50#endif
  51        /* FIX_PCIE_MCFG, */
  52        __end_of_fixed_addresses
  53};
  54
  55extern void __set_fixmap (enum fixed_addresses idx,
  56                                        phys_addr_t phys, pgprot_t flags);
  57
  58#define set_fixmap(idx, phys) \
  59                __set_fixmap(idx, phys, PAGE_KERNEL)
  60/*
  61 * Some hardware wants to get fixmapped without caching.
  62 */
  63#define set_fixmap_nocache(idx, phys) \
  64                __set_fixmap(idx, phys, PAGE_KERNEL_NCG)
  65
  66#define clear_fixmap(idx) \
  67                __set_fixmap(idx, 0, __pgprot(0))
  68
  69#define __FIXADDR_SIZE  (__end_of_fixed_addresses << PAGE_SHIFT)
  70#define FIXADDR_START           (FIXADDR_TOP - __FIXADDR_SIZE)
  71
  72#define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))
  73#define __virt_to_fix(x)        ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
  74
  75extern void __this_fixmap_does_not_exist(void);
  76
  77/*
  78 * 'index to address' translation. If anyone tries to use the idx
  79 * directly without tranlation, we catch the bug with a NULL-deference
  80 * kernel oops. Illegal ranges of incoming indices are caught too.
  81 */
  82static __always_inline unsigned long fix_to_virt(const unsigned int idx)
  83{
  84        /*
  85         * this branch gets completely eliminated after inlining,
  86         * except when someone tries to use fixaddr indices in an
  87         * illegal way. (such as mixing up address types or using
  88         * out-of-range indices).
  89         *
  90         * If it doesn't get removed, the linker will complain
  91         * loudly with a reasonably clear error message..
  92         */
  93        if (idx >= __end_of_fixed_addresses)
  94                __this_fixmap_does_not_exist();
  95
  96        return __fix_to_virt(idx);
  97}
  98
  99static inline unsigned long virt_to_fix(const unsigned long vaddr)
 100{
 101        BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
 102        return __virt_to_fix(vaddr);
 103}
 104
 105#endif /* !__ASSEMBLY__ */
 106#endif
 107