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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>
Jeremy Fitzhardinged6dd61c2007-05-02 19:27:14 +020018#include <asm-generic/mm_hooks.h>
Haavard Skinnemoen5f97f7f2006-09-25 23:32:13 -070019
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 */
36extern unsigned long mmu_context_cache;
37
38/*
39 * Get MMU context if needed
40 */
41static inline void
42get_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 */
72static 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 */
83static inline void destroy_context(struct mm_struct *mm)
84{
85 /* Do nothing */
86}
87
88static 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
95static 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
103static 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
109static 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
125static inline void
126enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
127{
128}
129
130
131static 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
144static inline void disable_mmu(void)
145{
146 sysreg_write(MMUCR, SYSREG_BIT(MMUCR_S));
147}
148
149#endif /* __ASM_AVR32_MMU_CONTEXT_H */