LXR linux/arch/mips/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 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
  11 */
  12
  13#ifndef _ASM_FIXMAP_H
  14#define _ASM_FIXMAP_H
  15
  16#include <asm/page.h>
  17#include <spaces.h>
  18#ifdef CONFIG_HIGHMEM
  19#include <linux/threads.h>
  20#include <asm/kmap_types.h>
  21#endif
  22
  23/*
  24 * Here we define all the compile-time 'special' virtual
  25 * addresses. The point is to have a constant address at
  26 * compile time, but to set the physical address only
  27 * in the boot process. We allocate these special  addresses
  28 * from the end of virtual memory (0xfffff000) backwards.
  29 * Also this lets us do fail-safe vmalloc(), we
  30 * can guarantee that these special addresses and
  31 * vmalloc()-ed addresses never overlap.
  32 *
  33 * these 'compile-time allocated' memory buffers are
  34 * fixed-size 4k pages. (or larger if used with an increment
  35 * highger than 1) use fixmap_set(idx,phys) to associate
  36 * physical memory with fixmap indices.
  37 *
  38 * TLB entries of such buffers will not be flushed across
  39 * task switches.
  40 */
  41
  42/*
  43 * on UP currently we will have no trace of the fixmap mechanizm,
  44 * no page table allocations, etc. This might change in the
  45 * future, say framebuffers for the console driver(s) could be
  46 * fix-mapped?
  47 */
  48enum fixed_addresses {
  49#define FIX_N_COLOURS 8
  50        FIX_CMAP_BEGIN,
  51        FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * 2),
  52#ifdef CONFIG_HIGHMEM
  53        /* reserved pte's for temporary kernel mappings */
  54        FIX_KMAP_BEGIN = FIX_CMAP_END + 1,
  55        FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
  56#endif
  57        __end_of_fixed_addresses
  58};
  59
  60/*
  61 * used by vmalloc.c.
  62 *
  63 * Leave one empty page between vmalloc'ed areas and
  64 * the start of the fixmap, and leave one page empty
  65 * at the top of mem..
  66 */
  67#define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)
  68#define FIXADDR_START   (FIXADDR_TOP - FIXADDR_SIZE)
  69
  70#include <asm-generic/fixmap.h>
  71
  72#define kmap_get_fixmap_pte(vaddr)                                      \
  73        pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), (vaddr))
  74
  75/*
  76 * Called from pgtable_init()
  77 */
  78extern void fixrange_init(unsigned long start, unsigned long end,
  79        pgd_t *pgd_base);
  80
  81
  82#endif
  83