| 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 */ |