summaryrefslogtreecommitdiffstats
path: root/kernel/arch/avr32/include/asm/mmu_context.h
blob: 27ff234071009b19e9f5f5dbeeadc52cefbcf0e1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
/*
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * ASID handling taken from SH implementation.
 *   Copyright (C) 1999 Niibe Yutaka
 *   Copyright (C) 2003 Paul Mundt
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#ifndef __ASM_AVR32_MMU_CONTEXT_H
#define __ASM_AVR32_MMU_CONTEXT_H

#include <asm/tlbflush.h>
#include <asm/sysreg.h>
#include <asm-generic/mm_hooks.h>

/*
 * The MMU "context" consists of two things:
 *    (a) TLB cache version
 *    (b) ASID (Address Space IDentifier)
 */
#define MMU_CONTEXT_ASID_MASK		0x000000ff
#define MMU_CONTEXT_VERSION_MASK	0xffffff00
#define MMU_CONTEXT_FIRST_VERSION       0x00000100
#define NO_CONTEXT			0

#define MMU_NO_ASID			0x100

/* Virtual Page Number mask */
#define MMU_VPN_MASK	0xfffff000

/* Cache of MMU context last used */
extern unsigned long mmu_context_cache;

/*
 * Get MMU context if needed
 */
static inline void
get_mmu_context(struct mm_struct *mm)
{
	unsigned long mc = mmu_context_cache;

	if (((mm->context ^ mc) & MMU_CONTEXT_VERSION_MASK) == 0)
		/* It's up to date, do nothing */
		return;

	/* It's old, we need to get new context with new version */
	mc = ++mmu_context_cache;
	if (!(mc & MMU_CONTEXT_ASID_MASK)) {
		/*
		 * We have exhausted all ASIDs of this version.
		 * Flush the TLB and start new cycle.
		 */
		flush_tlb_all();
		/*
		 * Fix version. Note that we avoid version #0
		 * to distinguish NO_CONTEXT.
		 */
		if (!mc)
			mmu_context_cache = mc = MMU_CONTEXT_FIRST_VERSION;
	}
	mm->context = mc;
}

/*
 * Initialize the context related info for a new mm_struct
 * instance.
 */
static inline int init_new_context(struct task_struct *tsk,
				       struct mm_struct *mm)
{
	mm->context = NO_CONTEXT;
	return 0;
}

/*
 * Destroy context related info for an mm_struct that is about
 * to be put to rest.
 */
static inline void destroy_context(struct mm_struct *mm)
{
	/* Do nothing */
}

static inline void set_asid(unsigned long asid)
{
	/* XXX: We're destroying TLBEHI[8:31] */
	sysreg_write(TLBEHI, asid & MMU_CONTEXT_ASID_MASK);
	cpu_sync_pipeline();
}

static inline unsigned long get_asid(void)
{
	unsigned long asid;

	asid = sysreg_read(TLBEHI);
	return asid & MMU_CONTEXT_ASID_MASK;
}

static inline void activate_context(struct mm_struct *mm)
{
	get_mmu_context(mm);
	set_asid(mm->context & MMU_CONTEXT_ASID_MASK);
}

static inline void switch_mm(struct mm_struct *prev,
				 struct mm_struct *next,
				 struct task_struct *tsk)
{
	if (likely(prev != next)) {
		unsigned long __pgdir = (unsigned long)next->pgd;

		sysreg_write(PTBR, __pgdir);
		activate_context(next);
	}
}

#define deactivate_mm(tsk,mm) do { } while(0)

#define activate_mm(prev, next) switch_mm((prev), (next), NULL)

static inline void
enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
}


static inline void enable_mmu(void)
{
	sysreg_write(MMUCR, (SYSREG_BIT(MMUCR_S)
			     | SYSREG_BIT(E)
			     | SYSREG_BIT(MMUCR_I)));
	nop(); nop(); nop(); nop(); nop(); nop(); nop(); nop();

	if (mmu_context_cache == NO_CONTEXT)
		mmu_context_cache = MMU_CONTEXT_FIRST_VERSION;

	set_asid(mmu_context_cache & MMU_CONTEXT_ASID_MASK);
}

static inline void disable_mmu(void)
{
	sysreg_write(MMUCR, SYSREG_BIT(MMUCR_S));
}

#endif /* __ASM_AVR32_MMU_CONTEXT_H */