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/sysreg.h>
17 #include <asm-generic/mm_hooks.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 */
35 extern unsigned long mmu_context_cache;
36
37 /*
38 * Get MMU context if needed
39 */
40 static inline void
get_mmu_context(struct mm_struct * mm)41 get_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 */
init_new_context(struct task_struct * tsk,struct mm_struct * mm)71 static 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 */
destroy_context(struct mm_struct * mm)82 static inline void destroy_context(struct mm_struct *mm)
83 {
84 /* Do nothing */
85 }
86
set_asid(unsigned long asid)87 static 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
get_asid(void)94 static 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
activate_context(struct mm_struct * mm)102 static 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
switch_mm(struct mm_struct * prev,struct mm_struct * next,struct task_struct * tsk)108 static 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
124 static inline void
enter_lazy_tlb(struct mm_struct * mm,struct task_struct * tsk)125 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
126 {
127 }
128
129
enable_mmu(void)130 static 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
disable_mmu(void)143 static inline void disable_mmu(void)
144 {
145 sysreg_write(MMUCR, SYSREG_BIT(MMUCR_S));
146 }
147
148 #endif /* __ASM_AVR32_MMU_CONTEXT_H */
149