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  */
  48 enum 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
  78 extern void __set_fixmap(enum fixed_addresses idx,
  79                          unsigned long phys, pgprot_t flags);
  80 extern 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