arch/powerpc/include/asm/highmem.h

   1 /*
   2  * highmem.h: virtual kernel memory mappings for high memory
   3  *
   4  * PowerPC version, stolen from the i386 version.
   5  *
   6  * Used in CONFIG_HIGHMEM systems for memory pages which
   7  * are not addressable by direct kernel virtual addresses.
   8  *
   9  * Copyright (C) 1999 Gerhard Wichert, Siemens AG
  10  *                    Gerhard.Wichert@pdb.siemens.de
  11  *
  12  *
  13  * Redesigned the x86 32-bit VM architecture to deal with
  14  * up to 16 Terrabyte physical memory. With current x86 CPUs
  15  * we now support up to 64 Gigabytes physical RAM.
  16  *
  17  * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
  18  */
  19
  20 #ifndef _ASM_HIGHMEM_H
  21 #define _ASM_HIGHMEM_H
  22
  23 #ifdef __KERNEL__
  24
  25 #include <linux/interrupt.h>
  26 #include <asm/kmap_types.h>
  27 #include <asm/tlbflush.h>
  28 #include <asm/page.h>
  29 #include <asm/fixmap.h>
  30
  31 extern pte_t *kmap_pte;
  32 extern pgprot_t kmap_prot;
  33 extern pte_t *pkmap_page_table;
  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 /*
  41  * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
  42  * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
  43  * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
  44  * in case of 16K/64K/256K page sizes.
  45  */
  46 #ifdef CONFIG_PPC_4K_PAGES
  47 #define PKMAP_ORDER     PTE_SHIFT
  48 #else
  49 #define PKMAP_ORDER     9
  50 #endif
  51 #define LAST_PKMAP      (1 << PKMAP_ORDER)
  52 #ifndef CONFIG_PPC_4K_PAGES
  53 #define PKMAP_BASE      (FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1))
  54 #else
  55 #define PKMAP_BASE      ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
  56 #endif
  57 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
  58 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
  59 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  60
  61 extern void *kmap_high(struct page *page);
  62 extern void kunmap_high(struct page *page);
  63 extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
  64 extern void __kunmap_atomic(void *kvaddr);
  65
  66 static inline void *kmap(struct page *page)
  67 {
  68         might_sleep();
  69         if (!PageHighMem(page))
  70                 return page_address(page);
  71         return kmap_high(page);
  72 }
  73
  74 static inline void kunmap(struct page *page)
  75 {
  76         BUG_ON(in_interrupt());
  77         if (!PageHighMem(page))
  78                 return;
  79         kunmap_high(page);
  80 }
  81
  82 static inline void *kmap_atomic(struct page *page)
  83 {
  84         return kmap_atomic_prot(page, kmap_prot);
  85 }
  86
  87 static inline struct page *kmap_atomic_to_page(void *ptr)
  88 {
  89         unsigned long idx, vaddr = (unsigned long) ptr;
  90         pte_t *pte;
  91
  92         if (vaddr < FIXADDR_START)
  93                 return virt_to_page(ptr);
  94
  95         idx = virt_to_fix(vaddr);
  96         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
  97         return pte_page(*pte);
  98 }
  99
 100
 101 #define flush_cache_kmaps()     flush_cache_all()
 102
 103 #endif /* __KERNEL__ */
 104
 105 #endif /* _ASM_HIGHMEM_H */