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 */
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 */
149