include/asm-mn10300/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 <asm/kmap_types.h>
  20 #include <asm/pgtable.h>
  21
  22 /* undef for production */
  23 #undef HIGHMEM_DEBUG
  24
  25 /* declarations for highmem.c */
  26 extern unsigned long highstart_pfn, highend_pfn;
  27
  28 extern pte_t *kmap_pte;
  29 extern pgprot_t kmap_prot;
  30 extern pte_t *pkmap_page_table;
  31
  32 extern void __init kmap_init(void);
  33
  34 /*
  35  * Right now we initialize only a single pte table. It can be extended
  36  * easily, subsequent pte tables have to be allocated in one physical
  37  * chunk of RAM.
  38  */
  39 #define PKMAP_BASE      0xfe000000UL
  40 #define LAST_PKMAP      1024
  41 #define LAST_PKMAP_MASK (LAST_PKMAP - 1)
  42 #define PKMAP_NR(virt)  ((virt - PKMAP_BASE) >> PAGE_SHIFT)
  43 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  44
  45 extern unsigned long kmap_high(struct page *page);
  46 extern void kunmap_high(struct page *page);
  47
  48 static inline unsigned long kmap(struct page *page)
  49 {
  50         if (in_interrupt())
  51                 BUG();
  52         if (page < highmem_start_page)
  53                 return page_address(page);
  54         return kmap_high(page);
  55 }
  56
  57 static inline void kunmap(struct page *page)
  58 {
  59         if (in_interrupt())
  60                 BUG();
  61         if (page < highmem_start_page)
  62                 return;
  63         kunmap_high(page);
  64 }
  65
  66 /*
  67  * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
  68  * gives a more generic (and caching) interface. But kmap_atomic can
  69  * be used in IRQ contexts, so in some (very limited) cases we need
  70  * it.
  71  */
  72 static inline unsigned long kmap_atomic(struct page *page, enum km_type type)
  73 {
  74         enum fixed_addresses idx;
  75         unsigned long vaddr;
  76
  77         if (page < highmem_start_page)
  78                 return page_address(page);
  79
  80         idx = type + KM_TYPE_NR * smp_processor_id();
  81         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  82 #if HIGHMEM_DEBUG
  83         if (!pte_none(*(kmap_pte - idx)))
  84                 BUG();
  85 #endif
  86         set_pte(kmap_pte - idx, mk_pte(page, kmap_prot));
  87         __flush_tlb_one(vaddr);
  88
  89         return vaddr;
  90 }
  91
  92 static inline void kunmap_atomic(unsigned long vaddr, enum km_type type)
  93 {
  94 #if HIGHMEM_DEBUG
  95         enum fixed_addresses idx = type + KM_TYPE_NR * smp_processor_id();
  96
  97         if (vaddr < FIXADDR_START) /* FIXME */
  98                 return;
  99
 100         if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx))
 101                 BUG();
 102
 103         /*
 104          * force other mappings to Oops if they'll try to access
 105          * this pte without first remap it
 106          */
 107         pte_clear(kmap_pte - idx);
 108         __flush_tlb_one(vaddr);
 109 #endif
 110 }
 111
 112 #endif /* __KERNEL__ */
 113
 114 #endif /* _ASM_HIGHMEM_H */