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