arch/microblaze/include/asm/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 <linux/uaccess.h>
  25 #include <asm/fixmap.h>
  26
  27 extern pte_t *kmap_pte;
  28 extern pgprot_t kmap_prot;
  29 extern pte_t *pkmap_page_table;
  30
  31 /*
  32  * Right now we initialize only a single pte table. It can be extended
  33  * easily, subsequent pte tables have to be allocated in one physical
  34  * chunk of RAM.
  35  */
  36 /*
  37  * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
  38  * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
  39  * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
  40  * in case of 16K/64K/256K page sizes.
  41  */
  42
  43 #define PKMAP_ORDER     PTE_SHIFT
  44 #define LAST_PKMAP      (1 << PKMAP_ORDER)
  45
  46 #define PKMAP_BASE      ((FIXADDR_START - PAGE_SIZE * (LAST_PKMAP + 1)) \
  47                                                                 & PMD_MASK)
  48
  49 #define LAST_PKMAP_MASK (LAST_PKMAP - 1)
  50 #define PKMAP_NR(virt)  ((virt - PKMAP_BASE) >> PAGE_SHIFT)
  51 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  52
  53 extern void *kmap_high(struct page *page);
  54 extern void kunmap_high(struct page *page);
  55 extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
  56 extern void __kunmap_atomic(void *kvaddr);
  57
  58 static inline void *kmap(struct page *page)
  59 {
  60         might_sleep();
  61         if (!PageHighMem(page))
  62                 return page_address(page);
  63         return kmap_high(page);
  64 }
  65
  66 static inline void kunmap(struct page *page)
  67 {
  68         BUG_ON(in_interrupt());
  69         if (!PageHighMem(page))
  70                 return;
  71         kunmap_high(page);
  72 }
  73
  74 static inline void *__kmap_atomic(struct page *page)
  75 {
  76         return kmap_atomic_prot(page, kmap_prot);
  77 }
  78
  79 static inline struct page *kmap_atomic_to_page(void *ptr)
  80 {
  81         unsigned long idx, vaddr = (unsigned long) ptr;
  82         pte_t *pte;
  83
  84         if (vaddr < FIXADDR_START)
  85                 return virt_to_page(ptr);
  86
  87         idx = virt_to_fix(vaddr);
  88         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
  89         return pte_page(*pte);
  90 }
  91
  92 #define flush_cache_kmaps()     { flush_icache(); flush_dcache(); }
  93
  94 #endif /* __KERNEL__ */
  95
  96 #endif /* _ASM_HIGHMEM_H */