include/asm-mips/highmem.h

   1 /*
   2  * highmem.h: virtual kernel memory mappings for high memory
   3  *
   4  * Used in CONFIG_HIGHMEM systems for memory pages which
   5  * are not addressable by direct kernel virtual addresses.
   6  *
   7  * Copyright (C) 1999 Gerhard Wichert, Siemens AG
   8  *                    Gerhard.Wichert@pdb.siemens.de
   9  *
  10  *
  11  * Redesigned the x86 32-bit VM architecture to deal with
  12  * up to 16 Terabyte physical memory. With current x86 CPUs
  13  * we now support up to 64 Gigabytes physical RAM.
  14  *
  15  * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
  16  */
  17 #ifndef _ASM_HIGHMEM_H
  18 #define _ASM_HIGHMEM_H
  19
  20 #ifdef __KERNEL__
  21
  22 #include <linux/init.h>
  23 #include <linux/interrupt.h>
  24 #include <asm/kmap_types.h>
  25
  26 /* undef for production */
  27 #define HIGHMEM_DEBUG 1
  28
  29 /* declarations for highmem.c */
  30 extern unsigned long highstart_pfn, highend_pfn;
  31
  32 extern pte_t *kmap_pte;
  33 extern pgprot_t kmap_prot;
  34 extern pte_t *pkmap_page_table;
  35
  36 /*
  37  * Right now we initialize only a single pte table. It can be extended
  38  * easily, subsequent pte tables have to be allocated in one physical
  39  * chunk of RAM.
  40  */
  41 #define PKMAP_BASE (0xfe000000UL)
  42 #define LAST_PKMAP 1024
  43 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
  44 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
  45 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  46
  47 extern void * kmap_high(struct page *page);
  48 extern void kunmap_high(struct page *page);
  49
  50 /*
  51  * CONFIG_LIMITED_DMA is for systems with DMA limitations such as Momentum's
  52  * Jaguar ATX.  This option exploits the highmem code in the kernel so is
  53  * always enabled together with CONFIG_HIGHMEM but at this time doesn't
  54  * actually add highmem functionality.
  55  */
  56
  57 #ifdef CONFIG_LIMITED_DMA
  58
  59 /*
  60  * These are the default functions for the no-highmem case from
  61  * <linux/highmem.h>
  62  */
  63 static inline void *kmap(struct page *page)
  64 {
  65         might_sleep();
  66         return page_address(page);
  67 }
  68
  69 #define kunmap(page) do { (void) (page); } while (0)
  70
  71 static inline void *kmap_atomic(struct page *page, enum km_type type)
  72 {
  73         return page_address(page);
  74 }
  75
  76 static inline void kunmap_atomic(void *kvaddr, enum km_type type) { }
  77 #define kmap_atomic_pfn(pfn, idx)       page_address(pfn_to_page(pfn))
  78
  79 #define kmap_atomic_to_page(ptr) virt_to_page(ptr)
  80
  81 #define flush_cache_kmaps()     do { } while (0)
  82
  83 #else /* LIMITED_DMA */
  84
  85 extern void *__kmap(struct page *page);
  86 extern void __kunmap(struct page *page);
  87 extern void *__kmap_atomic(struct page *page, enum km_type type);
  88 extern void __kunmap_atomic(void *kvaddr, enum km_type type);
  89 extern void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
  90 extern struct page *__kmap_atomic_to_page(void *ptr);
  91
  92 #define kmap                    __kmap
  93 #define kunmap                  __kunmap
  94 #define kmap_atomic             __kmap_atomic
  95 #define kunmap_atomic           __kunmap_atomic
  96 #define kmap_atomic_to_page     __kmap_atomic_to_page
  97
  98 #define flush_cache_kmaps()     flush_cache_all()
  99
 100 #endif /* LIMITED_DMA */
 101
 102 #endif /* __KERNEL__ */
 103
 104 #endif /* _ASM_HIGHMEM_H */