LXR linux/arch/mn10300/include/asm/highmem.h

   1/* MN10300 Virtual kernel memory mappings for high memory
   2 *
   3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 * - Derived from include/asm-i386/highmem.h
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public Licence
   9 * as published by the Free Software Foundation; either version
  10 * 2 of the Licence, or (at your option) any later version.
  11 */
  12#ifndef _ASM_HIGHMEM_H
  13#define _ASM_HIGHMEM_H
  14
  15#ifdef __KERNEL__
  16
  17#include <linux/init.h>
  18#include <linux/interrupt.h>
  19#include <linux/highmem.h>
  20#include <asm/kmap_types.h>
  21#include <asm/pgtable.h>
  22
  23/* undef for production */
  24#undef HIGHMEM_DEBUG
  25
  26/* declarations for highmem.c */
  27extern unsigned long highstart_pfn, highend_pfn;
  28
  29extern pte_t *kmap_pte;
  30extern pgprot_t kmap_prot;
  31extern pte_t *pkmap_page_table;
  32
  33extern void __init kmap_init(void);
  34
  35/*
  36 * Right now we initialize only a single pte table. It can be extended
  37 * easily, subsequent pte tables have to be allocated in one physical
  38 * chunk of RAM.
  39 */
  40#define PKMAP_BASE      0xfe000000UL
  41#define LAST_PKMAP      1024
  42#define LAST_PKMAP_MASK (LAST_PKMAP - 1)
  43#define PKMAP_NR(virt)  ((virt - PKMAP_BASE) >> PAGE_SHIFT)
  44#define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  45
  46extern unsigned long kmap_high(struct page *page);
  47extern void kunmap_high(struct page *page);
  48
  49static inline unsigned long kmap(struct page *page)
  50{
  51        if (in_interrupt())
  52                BUG();
  53        if (page < highmem_start_page)
  54                return page_address(page);
  55        return kmap_high(page);
  56}
  57
  58static inline void kunmap(struct page *page)
  59{
  60        if (in_interrupt())
  61                BUG();
  62        if (page < highmem_start_page)
  63                return;
  64        kunmap_high(page);
  65}
  66
  67/*
  68 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
  69 * gives a more generic (and caching) interface. But kmap_atomic can
  70 * be used in IRQ contexts, so in some (very limited) cases we need
  71 * it.
  72 */
  73static inline void *kmap_atomic(struct page *page)
  74{
  75        unsigned long vaddr;
  76        int idx, type;
  77
  78        preempt_disable();
  79        pagefault_disable();
  80        if (page < highmem_start_page)
  81                return page_address(page);
  82
  83        type = kmap_atomic_idx_push();
  84        idx = type + KM_TYPE_NR * smp_processor_id();
  85        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  86#if HIGHMEM_DEBUG
  87        if (!pte_none(*(kmap_pte - idx)))
  88                BUG();
  89#endif
  90        set_pte(kmap_pte - idx, mk_pte(page, kmap_prot));
  91        local_flush_tlb_one(vaddr);
  92
  93        return (void *)vaddr;
  94}
  95
  96static inline void __kunmap_atomic(unsigned long vaddr)
  97{
  98        int type;
  99
 100        if (vaddr < FIXADDR_START) { /* FIXME */
 101                pagefault_enable();
 102                preempt_enable();
 103                return;
 104        }
 105
 106        type = kmap_atomic_idx();
 107
 108#if HIGHMEM_DEBUG
 109        {
 110                unsigned int idx;
 111                idx = type + KM_TYPE_NR * smp_processor_id();
 112
 113                if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx))
 114                        BUG();
 115
 116                /*
 117                 * force other mappings to Oops if they'll try to access
 118                 * this pte without first remap it
 119                 */
 120                pte_clear(kmap_pte - idx);
 121                local_flush_tlb_one(vaddr);
 122        }
 123#endif
 124
 125        kmap_atomic_idx_pop();
 126        pagefault_enable();
 127        preempt_enable();
 128}
 129#endif /* __KERNEL__ */
 130
 131#endif /* _ASM_HIGHMEM_H */
 132