arch/metag/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 <asm/pgtable.h>
  17 #ifdef CONFIG_HIGHMEM
  18 #include <linux/threads.h>
  19 #include <asm/kmap_types.h>
  20 #endif
  21
  22 /*
  23  * Here we define all the compile-time 'special' virtual
  24  * addresses. The point is to have a constant address at
  25  * compile time, but to set the physical address only
  26  * in the boot process. We allocate these special  addresses
  27  * from the end of the consistent memory region backwards.
  28  * Also this lets us do fail-safe vmalloc(), we
  29  * can guarantee that these special addresses and
  30  * vmalloc()-ed addresses never overlap.
  31  *
  32  * these 'compile-time allocated' memory buffers are
  33  * fixed-size 4k pages. (or larger if used with an increment
  34  * higher than 1) use fixmap_set(idx,phys) to associate
  35  * physical memory with fixmap indices.
  36  *
  37  * TLB entries of such buffers will not be flushed across
  38  * task switches.
  39  */
  40 enum fixed_addresses {
  41 #define FIX_N_COLOURS 8
  42 #ifdef CONFIG_HIGHMEM
  43         /* reserved pte's for temporary kernel mappings */
  44         FIX_KMAP_BEGIN,
  45         FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
  46 #endif
  47         __end_of_fixed_addresses
  48 };
  49
  50 #define FIXADDR_TOP     (CONSISTENT_START - PAGE_SIZE)
  51 #define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)
  52 #define FIXADDR_START   ((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK)
  53
  54 #define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))
  55 #define __virt_to_fix(x)        ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
  56
  57 extern void __this_fixmap_does_not_exist(void);
  58 /*
  59  * 'index to address' translation. If anyone tries to use the idx
  60  * directly without tranlation, we catch the bug with a NULL-deference
  61  * kernel oops. Illegal ranges of incoming indices are caught too.
  62  */
  63 static inline unsigned long fix_to_virt(const unsigned int idx)
  64 {
  65         /*
  66          * this branch gets completely eliminated after inlining,
  67          * except when someone tries to use fixaddr indices in an
  68          * illegal way. (such as mixing up address types or using
  69          * out-of-range indices).
  70          *
  71          * If it doesn't get removed, the linker will complain
  72          * loudly with a reasonably clear error message..
  73          */
  74         if (idx >= __end_of_fixed_addresses)
  75                 __this_fixmap_does_not_exist();
  76
  77         return __fix_to_virt(idx);
  78 }
  79
  80 static inline unsigned long virt_to_fix(const unsigned long vaddr)
  81 {
  82         BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
  83         return __virt_to_fix(vaddr);
  84 }
  85
  86 #define kmap_get_fixmap_pte(vaddr) \
  87         pte_offset_kernel( \
  88                 pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \
  89                 (vaddr) \
  90         )
  91
  92 /*
  93  * Called from pgtable_init()
  94  */
  95 extern void fixrange_init(unsigned long start, unsigned long end,
  96         pgd_t *pgd_base);
  97
  98
  99 #endif