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

   1/*
   2 * Fixmap support for Hexagon - enough to support highmem features
   3 *
   4 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 and
   8 * only version 2 as published by the Free Software Foundation.
   9 *
  10 * This program is distributed in the hope that it will be useful,
  11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 * GNU General Public License for more details.
  14 *
  15 * You should have received a copy of the GNU General Public License
  16 * along with this program; if not, write to the Free Software
  17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18 * 02110-1301, USA.
  19 */
  20
  21#ifndef _ASM_FIXMAP_H
  22#define _ASM_FIXMAP_H
  23
  24/*
  25 * A lot of the fixmap info is already in mem-layout.h
  26 */
  27#include <asm/mem-layout.h>
  28
  29/*
  30 * Full fixmap support involves set_fixmap() functions, but
  31 * these may not be needed if all we're after is an area for
  32 * highmem kernel mappings.
  33 */
  34#define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))
  35#define __virt_to_fix(x)        ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
  36
  37extern void __this_fixmap_does_not_exist(void);
  38
  39/**
  40 * fix_to_virt -- "index to address" translation.
  41 *
  42 * If anyone tries to use the idx directly without translation,
  43 * we catch the bug with a NULL-deference kernel oops. Illegal
  44 * ranges of incoming indices are caught too.
  45 */
  46static inline unsigned long fix_to_virt(const unsigned int idx)
  47{
  48        /*
  49         * This branch gets completely eliminated after inlining,
  50         * except when someone tries to use fixaddr indices in an
  51         * illegal way. (such as mixing up address types or using
  52         * out-of-range indices).
  53         *
  54         * If it doesn't get removed, the linker will complain
  55         * loudly with a reasonably clear error message..
  56         */
  57        if (idx >= __end_of_fixed_addresses)
  58                __this_fixmap_does_not_exist();
  59
  60        return __fix_to_virt(idx);
  61}
  62
  63static inline unsigned long virt_to_fix(const unsigned long vaddr)
  64{
  65        BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
  66        return __virt_to_fix(vaddr);
  67}
  68
  69#define kmap_get_fixmap_pte(vaddr) \
  70        pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), \
  71                                (vaddr)), (vaddr)), (vaddr))
  72
  73#endif
  74