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
  37 extern 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  */
  46 static 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
  63 static 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