include/asm-avr32/mmu_context.h

   1 /*
   2  * Copyright (C) 2004-2006 Atmel Corporation
   3  *
   4  * ASID handling taken from SH implementation.
   5  *   Copyright (C) 1999 Niibe Yutaka
   6  *   Copyright (C) 2003 Paul Mundt
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #ifndef __ASM_AVR32_MMU_CONTEXT_H
  13 #define __ASM_AVR32_MMU_CONTEXT_H
  14
  15 #include <asm/tlbflush.h>
  16 #include <asm/pgalloc.h>
  17 #include <asm/sysreg.h>
  18 #include <asm-generic/mm_hooks.h>
  19
  20 /*
  21  * The MMU "context" consists of two things:
  22  *    (a) TLB cache version
  23  *    (b) ASID (Address Space IDentifier)
  24  */
  25 #define MMU_CONTEXT_ASID_MASK           0x000000ff
  26 #define MMU_CONTEXT_VERSION_MASK        0xffffff00
  27 #define MMU_CONTEXT_FIRST_VERSION       0x00000100
  28 #define NO_CONTEXT                      0
  29
  30 #define MMU_NO_ASID                     0x100
  31
  32 /* Virtual Page Number mask */
  33 #define MMU_VPN_MASK    0xfffff000
  34
  35 /* Cache of MMU context last used */
  36 extern unsigned long mmu_context_cache;
  37
  38 /*
  39  * Get MMU context if needed
  40  */
  41 static inline void
  42 get_mmu_context(struct mm_struct *mm)
  43 {
  44         unsigned long mc = mmu_context_cache;
  45
  46         if (((mm->context ^ mc) & MMU_CONTEXT_VERSION_MASK) == 0)
  47                 /* It's up to date, do nothing */
  48                 return;
  49
  50         /* It's old, we need to get new context with new version */
  51         mc = ++mmu_context_cache;
  52         if (!(mc & MMU_CONTEXT_ASID_MASK)) {
  53                 /*
  54                  * We have exhausted all ASIDs of this version.
  55                  * Flush the TLB and start new cycle.
  56                  */
  57                 flush_tlb_all();
  58                 /*
  59                  * Fix version. Note that we avoid version #0
  60                  * to distinguish NO_CONTEXT.
  61                  */
  62                 if (!mc)
  63                         mmu_context_cache = mc = MMU_CONTEXT_FIRST_VERSION;
  64         }
  65         mm->context = mc;
  66 }
  67
  68 /*
  69  * Initialize the context related info for a new mm_struct
  70  * instance.
  71  */
  72 static inline int init_new_context(struct task_struct *tsk,
  73                                        struct mm_struct *mm)
  74 {
  75         mm->context = NO_CONTEXT;
  76         return 0;
  77 }
  78
  79 /*
  80  * Destroy context related info for an mm_struct that is about
  81  * to be put to rest.
  82  */
  83 static inline void destroy_context(struct mm_struct *mm)
  84 {
  85         /* Do nothing */
  86 }
  87
  88 static inline void set_asid(unsigned long asid)
  89 {
  90         /* XXX: We're destroying TLBEHI[8:31] */
  91         sysreg_write(TLBEHI, asid & MMU_CONTEXT_ASID_MASK);
  92         cpu_sync_pipeline();
  93 }
  94
  95 static inline unsigned long get_asid(void)
  96 {
  97         unsigned long asid;
  98
  99         asid = sysreg_read(TLBEHI);
 100         return asid & MMU_CONTEXT_ASID_MASK;
 101 }
 102
 103 static inline void activate_context(struct mm_struct *mm)
 104 {
 105         get_mmu_context(mm);
 106         set_asid(mm->context & MMU_CONTEXT_ASID_MASK);
 107 }
 108
 109 static inline void switch_mm(struct mm_struct *prev,
 110                                  struct mm_struct *next,
 111                                  struct task_struct *tsk)
 112 {
 113         if (likely(prev != next)) {
 114                 unsigned long __pgdir = (unsigned long)next->pgd;
 115
 116                 sysreg_write(PTBR, __pgdir);
 117                 activate_context(next);
 118         }
 119 }
 120
 121 #define deactivate_mm(tsk,mm) do { } while(0)
 122
 123 #define activate_mm(prev, next) switch_mm((prev), (next), NULL)
 124
 125 static inline void
 126 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 127 {
 128 }
 129
 130
 131 static inline void enable_mmu(void)
 132 {
 133         sysreg_write(MMUCR, (SYSREG_BIT(MMUCR_S)
 134                              | SYSREG_BIT(E)
 135                              | SYSREG_BIT(MMUCR_I)));
 136         nop(); nop(); nop(); nop(); nop(); nop(); nop(); nop();
 137
 138         if (mmu_context_cache == NO_CONTEXT)
 139                 mmu_context_cache = MMU_CONTEXT_FIRST_VERSION;
 140
 141         set_asid(mmu_context_cache & MMU_CONTEXT_ASID_MASK);
 142 }
 143
 144 static inline void disable_mmu(void)
 145 {
 146         sysreg_write(MMUCR, SYSREG_BIT(MMUCR_S));
 147 }
 148
 149 #endif /* __ASM_AVR32_MMU_CONTEXT_H */