LXR linux/arch/sh/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 <linux/kernel.h>
  17#include <linux/threads.h>
  18#include <asm/page.h>
  19#ifdef CONFIG_HIGHMEM
  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 P3 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        /*
  50         * The FIX_CMAP entries are used by kmap_coherent() to get virtual
  51         * addresses which are of a known color, and so their values are
  52         * important. __fix_to_virt(FIX_CMAP_END - n) must give an address
  53         * which is the same color as a page (n<<PAGE_SHIFT).
  54         */
  55#define FIX_N_COLOURS 8
  56        FIX_CMAP_BEGIN,
  57        FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1,
  58
  59#ifdef CONFIG_HIGHMEM
  60        FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
  61        FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
  62#endif
  63
  64#ifdef CONFIG_IOREMAP_FIXED
  65        /*
  66         * FIX_IOREMAP entries are useful for mapping physical address
  67         * space before ioremap() is useable, e.g. really early in boot
  68         * before kmalloc() is working.
  69         */
  70#define FIX_N_IOREMAPS  32
  71        FIX_IOREMAP_BEGIN,
  72        FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
  73#endif
  74
  75        __end_of_fixed_addresses
  76};
  77
  78extern void __set_fixmap(enum fixed_addresses idx,
  79                         unsigned long phys, pgprot_t flags);
  80extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags);
  81
  82/*
  83 * used by vmalloc.c.
  84 *
  85 * Leave one empty page between vmalloc'ed areas and
  86 * the start of the fixmap, and leave one page empty
  87 * at the top of mem..
  88 */
  89#ifdef CONFIG_SUPERH32
  90#define FIXADDR_TOP     (P4SEG - PAGE_SIZE)
  91#else
  92#define FIXADDR_TOP     ((unsigned long)(-PAGE_SIZE))
  93#endif
  94#define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)
  95#define FIXADDR_START   (FIXADDR_TOP - FIXADDR_SIZE)
  96
  97#define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
  98
  99#include <asm-generic/fixmap.h>
 100
 101#endif
 102