1/*
2 * include/asm-xtensa/mmu_context.h
3 *
4 * Switch an MMU context.
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License.  See the file "COPYING" in the main directory of this archive
8 * for more details.
9 *
10 * Copyright (C) 2001 - 2005 Tensilica Inc.
11 */
12
13#ifndef _XTENSA_MMU_CONTEXT_H
14#define _XTENSA_MMU_CONTEXT_H
15
16#include <linux/stringify.h>
17#include <linux/sched.h>
18
19#include <asm/pgtable.h>
20#include <asm/cacheflush.h>
21#include <asm/tlbflush.h>
22#include <asm-generic/mm_hooks.h>
23
24#define XCHAL_MMU_ASID_BITS	8
25
26#if (XCHAL_HAVE_TLBS != 1)
27# error "Linux must have an MMU!"
28#endif
29
30extern unsigned long asid_cache;
31
32/*
33 * NO_CONTEXT is the invalid ASID value that we don't ever assign to
34 * any user or kernel context.
35 *
36 * 0 invalid
37 * 1 kernel
38 * 2 reserved
39 * 3 reserved
40 * 4...255 available
41 */
42
43#define NO_CONTEXT	0
44#define ASID_USER_FIRST	4
45#define ASID_MASK	((1 << XCHAL_MMU_ASID_BITS) - 1)
46#define ASID_INSERT(x)	(0x03020001 | (((x) & ASID_MASK) << 8))
47
48static inline void set_rasid_register (unsigned long val)
49{
50	__asm__ __volatile__ (" wsr %0, "__stringify(RASID)"\n\t"
51			      " isync\n" : : "a" (val));
52}
53
54static inline unsigned long get_rasid_register (void)
55{
56	unsigned long tmp;
57	__asm__ __volatile__ (" rsr %0,"__stringify(RASID)"\n\t" : "=a" (tmp));
58	return tmp;
59}
60
61static inline void
62__get_new_mmu_context(struct mm_struct *mm)
63{
64	extern void flush_tlb_all(void);
65	if (! (++asid_cache & ASID_MASK) ) {
66		flush_tlb_all(); /* start new asid cycle */
67		asid_cache += ASID_USER_FIRST;
68	}
69	mm->context = asid_cache;
70}
71
72static inline void
73__load_mmu_context(struct mm_struct *mm)
74{
75	set_rasid_register(ASID_INSERT(mm->context));
76	invalidate_page_directory();
77}
78
79/*
80 * Initialize the context related info for a new mm_struct
81 * instance.
82 */
83
84static inline int
85init_new_context(struct task_struct *tsk, struct mm_struct *mm)
86{
87	mm->context = NO_CONTEXT;
88	return 0;
89}
90
91/*
92 * After we have set current->mm to a new value, this activates
93 * the context for the new mm so we see the new mappings.
94 */
95static inline void
96activate_mm(struct mm_struct *prev, struct mm_struct *next)
97{
98	/* Unconditionally get a new ASID.  */
99
100	__get_new_mmu_context(next);
101	__load_mmu_context(next);
102}
103
104
105static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
106                             struct task_struct *tsk)
107{
108	unsigned long asid = asid_cache;
109
110	/* Check if our ASID is of an older version and thus invalid */
111
112	if (next->context == NO_CONTEXT || ((next->context^asid) & ~ASID_MASK))
113		__get_new_mmu_context(next);
114
115	__load_mmu_context(next);
116}
117
118#define deactivate_mm(tsk, mm)	do { } while(0)
119
120/*
121 * Destroy context related info for an mm_struct that is about
122 * to be put to rest.
123 */
124static inline void destroy_context(struct mm_struct *mm)
125{
126	invalidate_page_directory();
127}
128
129
130static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
131{
132	/* Nothing to do. */
133
134}
135
136#endif /* _XTENSA_MMU_CONTEXT_H */
137