arch/avr32/include/asm/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 <linux/mm_types.h>
  16
  17 #include <asm/tlbflush.h>
  18 #include <asm/sysreg.h>
  19 #include <asm-generic/mm_hooks.h>
  20
  21 /*
  22  * The MMU "context" consists of two things:
  23  *    (a) TLB cache version
  24  *    (b) ASID (Address Space IDentifier)
  25  */
  26 #define MMU_CONTEXT_ASID_MASK           0x000000ff
  27 #define MMU_CONTEXT_VERSION_MASK        0xffffff00
  28 #define MMU_CONTEXT_FIRST_VERSION       0x00000100
  29 #define NO_CONTEXT                      0
  30
  31 #define MMU_NO_ASID                     0x100
  32
  33 /* Virtual Page Number mask */
  34 #define MMU_VPN_MASK    0xfffff000
  35
  36 /* Cache of MMU context last used */
  37 extern unsigned long mmu_context_cache;
  38
  39 /*
  40  * Get MMU context if needed
  41  */
  42 static inline void
  43 get_mmu_context(struct mm_struct *mm)
  44 {
  45         unsigned long mc = mmu_context_cache;
  46
  47         if (((mm->context ^ mc) & MMU_CONTEXT_VERSION_MASK) == 0)
  48                 /* It's up to date, do nothing */
  49                 return;
  50
  51         /* It's old, we need to get new context with new version */
  52         mc = ++mmu_context_cache;
  53         if (!(mc & MMU_CONTEXT_ASID_MASK)) {
  54                 /*
  55                  * We have exhausted all ASIDs of this version.
  56                  * Flush the TLB and start new cycle.
  57                  */
  58                 flush_tlb_all();
  59                 /*
  60                  * Fix version. Note that we avoid version #0
  61                  * to distinguish NO_CONTEXT.
  62                  */
  63                 if (!mc)
  64                         mmu_context_cache = mc = MMU_CONTEXT_FIRST_VERSION;
  65         }
  66         mm->context = mc;
  67 }
  68
  69 /*
  70  * Initialize the context related info for a new mm_struct
  71  * instance.
  72  */
  73 static inline int init_new_context(struct task_struct *tsk,
  74                                        struct mm_struct *mm)
  75 {
  76         mm->context = NO_CONTEXT;
  77         return 0;
  78 }
  79
  80 /*
  81  * Destroy context related info for an mm_struct that is about
  82  * to be put to rest.
  83  */
  84 static inline void destroy_context(struct mm_struct *mm)
  85 {
  86         /* Do nothing */
  87 }
  88
  89 static inline void set_asid(unsigned long asid)
  90 {
  91         /* XXX: We're destroying TLBEHI[8:31] */
  92         sysreg_write(TLBEHI, asid & MMU_CONTEXT_ASID_MASK);
  93         cpu_sync_pipeline();
  94 }
  95
  96 static inline unsigned long get_asid(void)
  97 {
  98         unsigned long asid;
  99
 100         asid = sysreg_read(TLBEHI);
 101         return asid & MMU_CONTEXT_ASID_MASK;
 102 }
 103
 104 static inline void activate_context(struct mm_struct *mm)
 105 {
 106         get_mmu_context(mm);
 107         set_asid(mm->context & MMU_CONTEXT_ASID_MASK);
 108 }
 109
 110 static inline void switch_mm(struct mm_struct *prev,
 111                                  struct mm_struct *next,
 112                                  struct task_struct *tsk)
 113 {
 114         if (likely(prev != next)) {
 115                 unsigned long __pgdir = (unsigned long)next->pgd;
 116
 117                 sysreg_write(PTBR, __pgdir);
 118                 activate_context(next);
 119         }
 120 }
 121
 122 #define deactivate_mm(tsk,mm) do { } while(0)
 123
 124 #define activate_mm(prev, next) switch_mm((prev), (next), NULL)
 125
 126 static inline void
 127 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 128 {
 129 }
 130
 131
 132 static inline void enable_mmu(void)
 133 {
 134         sysreg_write(MMUCR, (SYSREG_BIT(MMUCR_S)
 135                              | SYSREG_BIT(E)
 136                              | SYSREG_BIT(MMUCR_I)));
 137         nop(); nop(); nop(); nop(); nop(); nop(); nop(); nop();
 138
 139         if (mmu_context_cache == NO_CONTEXT)
 140                 mmu_context_cache = MMU_CONTEXT_FIRST_VERSION;
 141
 142         set_asid(mmu_context_cache & MMU_CONTEXT_ASID_MASK);
 143 }
 144
 145 static inline void disable_mmu(void)
 146 {
 147         sysreg_write(MMUCR, SYSREG_BIT(MMUCR_S));
 148 }
 149
 150 #endif /* __ASM_AVR32_MMU_CONTEXT_H */