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 */
  27 extern unsigned long highstart_pfn, highend_pfn;
  28
  29 extern pte_t *kmap_pte;
  30 extern pgprot_t kmap_prot;
  31 extern pte_t *pkmap_page_table;
  32
  33 extern 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
  46 extern unsigned long kmap_high(struct page *page);
  47 extern void kunmap_high(struct page *page);
  48
  49 static 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
  58 static 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  */
  73 static inline void *kmap_atomic(struct page *page)
  74 {
  75         unsigned long vaddr;
  76         int idx, type;
  77
  78         pagefault_disable();
  79         if (page < highmem_start_page)
  80                 return page_address(page);
  81
  82         type = kmap_atomic_idx_push();
  83         idx = type + KM_TYPE_NR * smp_processor_id();
  84         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  85 #if HIGHMEM_DEBUG
  86         if (!pte_none(*(kmap_pte - idx)))
  87                 BUG();
  88 #endif
  89         set_pte(kmap_pte - idx, mk_pte(page, kmap_prot));
  90         local_flush_tlb_one(vaddr);
  91
  92         return (void *)vaddr;
  93 }
  94
  95 static inline void __kunmap_atomic(unsigned long vaddr)
  96 {
  97         int type;
  98
  99         if (vaddr < FIXADDR_START) { /* FIXME */
 100                 pagefault_enable();
 101                 return;
 102         }
 103
 104         type = kmap_atomic_idx();
 105
 106 #if HIGHMEM_DEBUG
 107         {
 108                 unsigned int idx;
 109                 idx = type + KM_TYPE_NR * smp_processor_id();
 110
 111                 if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx))
 112                         BUG();
 113
 114                 /*
 115                  * force other mappings to Oops if they'll try to access
 116                  * this pte without first remap it
 117                  */
 118                 pte_clear(kmap_pte - idx);
 119                 local_flush_tlb_one(vaddr);
 120         }
 121 #endif
 122
 123         kmap_atomic_idx_pop();
 124         pagefault_enable();
 125 }
 126 #endif /* __KERNEL__ */
 127
 128 #endif /* _ASM_HIGHMEM_H */