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        /* 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
  58extern 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
  78extern 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 */
  85static __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
 102static 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
 110