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Haavard Skinnemoen5f97f7f2006-09-25 23:32:13 -07001/*
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
19/*
20 * The MMU "context" consists of two things:
21 * (a) TLB cache version
22 * (b) ASID (Address Space IDentifier)
23 */
24#define MMU_CONTEXT_ASID_MASK 0x000000ff
25#define MMU_CONTEXT_VERSION_MASK 0xffffff00
26#define MMU_CONTEXT_FIRST_VERSION 0x00000100
27#define NO_CONTEXT 0
28
29#define MMU_NO_ASID 0x100
30
31/* Virtual Page Number mask */
32#define MMU_VPN_MASK 0xfffff000
33
34/* Cache of MMU context last used */
35extern unsigned long mmu_context_cache;
36
37/*
38 * Get MMU context if needed
39 */
40static inline void
41get_mmu_context(struct mm_struct *mm)
42{
43 unsigned long mc = mmu_context_cache;
44
45 if (((mm->context ^ mc) & MMU_CONTEXT_VERSION_MASK) == 0)
46 /* It's up to date, do nothing */
47 return;
48
49 /* It's old, we need to get new context with new version */
50 mc = ++mmu_context_cache;
51 if (!(mc & MMU_CONTEXT_ASID_MASK)) {
52 /*
53 * We have exhausted all ASIDs of this version.
54 * Flush the TLB and start new cycle.
55 */
56 flush_tlb_all();
57 /*
58 * Fix version. Note that we avoid version #0
59 * to distinguish NO_CONTEXT.
60 */
61 if (!mc)
62 mmu_context_cache = mc = MMU_CONTEXT_FIRST_VERSION;
63 }
64 mm->context = mc;
65}
66
67/*
68 * Initialize the context related info for a new mm_struct
69 * instance.
70 */
71static inline int init_new_context(struct task_struct *tsk,
72 struct mm_struct *mm)
73{
74 mm->context = NO_CONTEXT;
75 return 0;
76}
77
78/*
79 * Destroy context related info for an mm_struct that is about
80 * to be put to rest.
81 */
82static inline void destroy_context(struct mm_struct *mm)
83{
84 /* Do nothing */
85}
86
87static inline void set_asid(unsigned long asid)
88{
89 /* XXX: We're destroying TLBEHI[8:31] */
90 sysreg_write(TLBEHI, asid & MMU_CONTEXT_ASID_MASK);
91 cpu_sync_pipeline();
92}
93
94static inline unsigned long get_asid(void)
95{
96 unsigned long asid;
97
98 asid = sysreg_read(TLBEHI);
99 return asid & MMU_CONTEXT_ASID_MASK;
100}
101
102static inline void activate_context(struct mm_struct *mm)
103{
104 get_mmu_context(mm);
105 set_asid(mm->context & MMU_CONTEXT_ASID_MASK);
106}
107
108static inline void switch_mm(struct mm_struct *prev,
109 struct mm_struct *next,
110 struct task_struct *tsk)
111{
112 if (likely(prev != next)) {
113 unsigned long __pgdir = (unsigned long)next->pgd;
114
115 sysreg_write(PTBR, __pgdir);
116 activate_context(next);
117 }
118}
119
120#define deactivate_mm(tsk,mm) do { } while(0)
121
122#define activate_mm(prev, next) switch_mm((prev), (next), NULL)
123
124static inline void
125enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
126{
127}
128
129
130static inline void enable_mmu(void)
131{
132 sysreg_write(MMUCR, (SYSREG_BIT(MMUCR_S)
133 | SYSREG_BIT(E)
134 | SYSREG_BIT(MMUCR_I)));
135 nop(); nop(); nop(); nop(); nop(); nop(); nop(); nop();
136
137 if (mmu_context_cache == NO_CONTEXT)
138 mmu_context_cache = MMU_CONTEXT_FIRST_VERSION;
139
140 set_asid(mmu_context_cache & MMU_CONTEXT_ASID_MASK);
141}
142
143static inline void disable_mmu(void)
144{
145 sysreg_write(MMUCR, SYSREG_BIT(MMUCR_S));
146}
147
148#endif /* __ASM_AVR32_MMU_CONTEXT_H */