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/fixmap.h>
25#include <asm/vaddrs.h>
26#include <asm/kmap_types.h>
27#include <asm/pgtable.h>
28
29/* declarations for highmem.c */
30extern unsigned long highstart_pfn, highend_pfn;
31
32extern pte_t *kmap_pte;
33extern pgprot_t kmap_prot;
34extern pte_t *pkmap_page_table;
35
36extern void kmap_init(void) __init;
37
38/*
39 * Right now we initialize only a single pte table. It can be extended
40 * easily, subsequent pte tables have to be allocated in one physical
41 * chunk of RAM.  Currently the simplest way to do this is to align the
42 * pkmap region on a pagetable boundary (4MB).
43 */
44#define LAST_PKMAP 1024
45#define PKMAP_SIZE (LAST_PKMAP << PAGE_SHIFT)
46#define PKMAP_BASE PMD_ALIGN(SRMMU_NOCACHE_VADDR + (SRMMU_MAX_NOCACHE_PAGES << PAGE_SHIFT))
47
48#define LAST_PKMAP_MASK (LAST_PKMAP - 1)
49#define PKMAP_NR(virt)  ((virt - PKMAP_BASE) >> PAGE_SHIFT)
50#define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
51
52#define PKMAP_END (PKMAP_ADDR(LAST_PKMAP))
53
54extern void *kmap_high(struct page *page);
55extern void kunmap_high(struct page *page);
56
57static inline void *kmap(struct page *page)
58{
59	BUG_ON(in_interrupt());
60	if (!PageHighMem(page))
61		return page_address(page);
62	return kmap_high(page);
63}
64
65static inline void kunmap(struct page *page)
66{
67	BUG_ON(in_interrupt());
68	if (!PageHighMem(page))
69		return;
70	kunmap_high(page);
71}
72
73extern void *kmap_atomic(struct page *page, enum km_type type);
74extern void kunmap_atomic(void *kvaddr, enum km_type type);
75extern struct page *kmap_atomic_to_page(void *vaddr);
76
77#define flush_cache_kmaps()	flush_cache_all()
78
79#endif /* __KERNEL__ */
80
81#endif /* _ASM_HIGHMEM_H */
82