LXR linux/arch/sh/include/asm/fixmap.h

   1/* SPDX-License-Identifier: GPL-2.0
   2 *
   3 * fixmap.h: compile-time virtual memory allocation
   4 *
   5 * Copyright (C) 1998 Ingo Molnar
   6 *
   7 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
   8 */
   9
  10#ifndef _ASM_FIXMAP_H
  11#define _ASM_FIXMAP_H
  12
  13#include <linux/kernel.h>
  14#include <linux/threads.h>
  15#include <asm/page.h>
  16#ifdef CONFIG_HIGHMEM
  17#include <asm/kmap_types.h>
  18#endif
  19
  20/*
  21 * Here we define all the compile-time 'special' virtual
  22 * addresses. The point is to have a constant address at
  23 * compile time, but to set the physical address only
  24 * in the boot process. We allocate these special  addresses
  25 * from the end of P3 backwards.
  26 * Also this lets us do fail-safe vmalloc(), we
  27 * can guarantee that these special addresses and
  28 * vmalloc()-ed addresses never overlap.
  29 *
  30 * these 'compile-time allocated' memory buffers are
  31 * fixed-size 4k pages. (or larger if used with an increment
  32 * highger than 1) use fixmap_set(idx,phys) to associate
  33 * physical memory with fixmap indices.
  34 *
  35 * TLB entries of such buffers will not be flushed across
  36 * task switches.
  37 */
  38
  39/*
  40 * on UP currently we will have no trace of the fixmap mechanizm,
  41 * no page table allocations, etc. This might change in the
  42 * future, say framebuffers for the console driver(s) could be
  43 * fix-mapped?
  44 */
  45enum fixed_addresses {
  46        /*
  47         * The FIX_CMAP entries are used by kmap_coherent() to get virtual
  48         * addresses which are of a known color, and so their values are
  49         * important. __fix_to_virt(FIX_CMAP_END - n) must give an address
  50         * which is the same color as a page (n<<PAGE_SHIFT).
  51         */
  52#define FIX_N_COLOURS 8
  53        FIX_CMAP_BEGIN,
  54        FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1,
  55
  56#ifdef CONFIG_HIGHMEM
  57        FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
  58        FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
  59#endif
  60
  61#ifdef CONFIG_IOREMAP_FIXED
  62        /*
  63         * FIX_IOREMAP entries are useful for mapping physical address
  64         * space before ioremap() is useable, e.g. really early in boot
  65         * before kmalloc() is working.
  66         */
  67#define FIX_N_IOREMAPS  32
  68        FIX_IOREMAP_BEGIN,
  69        FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
  70#endif
  71
  72        __end_of_fixed_addresses
  73};
  74
  75extern void __set_fixmap(enum fixed_addresses idx,
  76                         unsigned long phys, pgprot_t flags);
  77extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags);
  78
  79/*
  80 * used by vmalloc.c.
  81 *
  82 * Leave one empty page between vmalloc'ed areas and
  83 * the start of the fixmap, and leave one page empty
  84 * at the top of mem..
  85 */
  86#ifdef CONFIG_SUPERH32
  87#define FIXADDR_TOP     (P4SEG - PAGE_SIZE)
  88#else
  89#define FIXADDR_TOP     ((unsigned long)(-PAGE_SIZE))
  90#endif
  91#define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)
  92#define FIXADDR_START   (FIXADDR_TOP - FIXADDR_SIZE)
  93
  94#define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
  95
  96#include <asm-generic/fixmap.h>
  97
  98#endif
  99