mmu_context.h
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/*
* 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 */