1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Copyright (C) 1999 Niibe Yutaka
4 * Copyright (C) 2003 - 2007 Paul Mundt
5 *
6 * ASID handling idea taken from MIPS implementation.
7 */
8#ifndef __ASM_SH_MMU_CONTEXT_H
9#define __ASM_SH_MMU_CONTEXT_H
10
11#include <cpu/mmu_context.h>
12#include <asm/tlbflush.h>
13#include <linux/uaccess.h>
14#include <linux/mm_types.h>
15
16#include <asm/io.h>
17#include <asm-generic/mm_hooks.h>
18
19/*
20 * The MMU "context" consists of two things:
21 *    (a) TLB cache version (or round, cycle whatever expression you like)
22 *    (b) ASID (Address Space IDentifier)
23 */
24#ifdef CONFIG_CPU_HAS_PTEAEX
25#define MMU_CONTEXT_ASID_MASK		0x0000ffff
26#else
27#define MMU_CONTEXT_ASID_MASK		0x000000ff
28#endif
29
30#define MMU_CONTEXT_VERSION_MASK	(~0UL & ~MMU_CONTEXT_ASID_MASK)
31#define MMU_CONTEXT_FIRST_VERSION	(MMU_CONTEXT_ASID_MASK + 1)
32
33/* Impossible ASID value, to differentiate from NO_CONTEXT. */
34#define MMU_NO_ASID			MMU_CONTEXT_FIRST_VERSION
35#define NO_CONTEXT			0UL
36
37#define asid_cache(cpu)		(cpu_data[cpu].asid_cache)
38
39#ifdef CONFIG_MMU
40#define cpu_context(cpu, mm)	((mm)->context.id[cpu])
41
42#define cpu_asid(cpu, mm)	\
43	(cpu_context((cpu), (mm)) & MMU_CONTEXT_ASID_MASK)
44
45/*
46 * Virtual Page Number mask
47 */
48#define MMU_VPN_MASK	0xfffff000
49
50#include <asm/mmu_context_32.h>
51
52/*
53 * Get MMU context if needed.
54 */
55static inline void get_mmu_context(struct mm_struct *mm, unsigned int cpu)
56{
57	unsigned long asid = asid_cache(cpu);
58
59	/* Check if we have old version of context. */
60	if (((cpu_context(cpu, mm) ^ asid) & MMU_CONTEXT_VERSION_MASK) == 0)
61		/* It's up to date, do nothing */
62		return;
63
64	/* It's old, we need to get new context with new version. */
65	if (!(++asid & MMU_CONTEXT_ASID_MASK)) {
66		/*
67		 * We exhaust ASID of this version.
68		 * Flush all TLB and start new cycle.
69		 */
70		local_flush_tlb_all();
71
72		/*
73		 * Fix version; Note that we avoid version #0
74		 * to distinguish NO_CONTEXT.
75		 */
76		if (!asid)
77			asid = MMU_CONTEXT_FIRST_VERSION;
78	}
79
80	cpu_context(cpu, mm) = asid_cache(cpu) = asid;
81}
82
83/*
84 * Initialize the context related info for a new mm_struct
85 * instance.
86 */
87#define init_new_context init_new_context
88static inline int init_new_context(struct task_struct *tsk,
89				   struct mm_struct *mm)
90{
91	int i;
92
93	for_each_online_cpu(i)
94		cpu_context(i, mm) = NO_CONTEXT;
95
96	return 0;
97}
98
99/*
100 * After we have set current->mm to a new value, this activates
101 * the context for the new mm so we see the new mappings.
102 */
103static inline void activate_context(struct mm_struct *mm, unsigned int cpu)
104{
105	get_mmu_context(mm, cpu);
106	set_asid(cpu_asid(cpu, mm));
107}
108
109static inline void switch_mm(struct mm_struct *prev,
110			     struct mm_struct *next,
111			     struct task_struct *tsk)
112{
113	unsigned int cpu = smp_processor_id();
114
115	if (likely(prev != next)) {
116		cpumask_set_cpu(cpu, mm_cpumask(next));
117		set_TTB(next->pgd);
118		activate_context(next, cpu);
119	} else
120		if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)))
121			activate_context(next, cpu);
122}
123
124#include <asm-generic/mmu_context.h>
125
126#else
127
128#define set_asid(asid)			do { } while (0)
129#define get_asid()			(0)
130#define cpu_asid(cpu, mm)		({ (void)cpu; NO_CONTEXT; })
131#define switch_and_save_asid(asid)	(0)
132#define set_TTB(pgd)			do { } while (0)
133#define get_TTB()			(0)
134
135#include <asm-generic/nommu_context.h>
136
137#endif /* CONFIG_MMU */
138
139#if defined(CONFIG_CPU_SH3) || defined(CONFIG_CPU_SH4)
140/*
141 * If this processor has an MMU, we need methods to turn it off/on ..
142 * paging_init() will also have to be updated for the processor in
143 * question.
144 */
145static inline void enable_mmu(void)
146{
147	unsigned int cpu = smp_processor_id();
148
149	/* Enable MMU */
150	__raw_writel(MMU_CONTROL_INIT, MMUCR);
151	ctrl_barrier();
152
153	if (asid_cache(cpu) == NO_CONTEXT)
154		asid_cache(cpu) = MMU_CONTEXT_FIRST_VERSION;
155
156	set_asid(asid_cache(cpu) & MMU_CONTEXT_ASID_MASK);
157}
158
159static inline void disable_mmu(void)
160{
161	unsigned long cr;
162
163	cr = __raw_readl(MMUCR);
164	cr &= ~MMU_CONTROL_INIT;
165	__raw_writel(cr, MMUCR);
166
167	ctrl_barrier();
168}
169#else
170/*
171 * MMU control handlers for processors lacking memory
172 * management hardware.
173 */
174#define enable_mmu()	do { } while (0)
175#define disable_mmu()	do { } while (0)
176#endif
177
178#endif /* __ASM_SH_MMU_CONTEXT_H */
179