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 Terrabyte 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
18#ifndef _ASM_HIGHMEM_H
19#define _ASM_HIGHMEM_H
20
21#ifdef __KERNEL__
22
23#include <linux/interrupt.h>
24#include <asm/vaddrs.h>
25#include <asm/kmap_types.h>
26#include <asm/pgtable.h>
27
28/* declarations for highmem.c */
29extern unsigned long highstart_pfn, highend_pfn;
30
31extern pgprot_t kmap_prot;
32extern pte_t *pkmap_page_table;
33
34void kmap_init(void) __init;
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.  Currently the simplest way to do this is to align the
40 * pkmap region on a pagetable boundary (4MB).
41 */
42#define LAST_PKMAP 1024
43#define PKMAP_SIZE (LAST_PKMAP << PAGE_SHIFT)
44#define PKMAP_BASE PMD_ALIGN(SRMMU_NOCACHE_VADDR + (SRMMU_MAX_NOCACHE_PAGES << PAGE_SHIFT))
45
46#define LAST_PKMAP_MASK (LAST_PKMAP - 1)
47#define PKMAP_NR(virt)  ((virt - PKMAP_BASE) >> PAGE_SHIFT)
48#define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
49
50#define PKMAP_END (PKMAP_ADDR(LAST_PKMAP))
51
52void *kmap_high(struct page *page);
53void kunmap_high(struct page *page);
54
55static inline void *kmap(struct page *page)
56{
57	BUG_ON(in_interrupt());
58	if (!PageHighMem(page))
59		return page_address(page);
60	return kmap_high(page);
61}
62
63static inline void kunmap(struct page *page)
64{
65	BUG_ON(in_interrupt());
66	if (!PageHighMem(page))
67		return;
68	kunmap_high(page);
69}
70
71void *kmap_atomic(struct page *page);
72void __kunmap_atomic(void *kvaddr);
73
74#define flush_cache_kmaps()	flush_cache_all()
75
76#endif /* __KERNEL__ */
77
78#endif /* _ASM_HIGHMEM_H */
79