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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/config.h>
23#include <linux/init.h>
24#include <linux/interrupt.h>
25#include <asm/kmap_types.h>
26
27/* undef for production */
28#define HIGHMEM_DEBUG 1
29
30/* declarations for highmem.c */
31extern unsigned long highstart_pfn, highend_pfn;
32
33extern pte_t *kmap_pte;
34extern pgprot_t kmap_prot;
35extern pte_t *pkmap_page_table;
36
37/*
38 * Right now we initialize only a single pte table. It can be extended
39 * easily, subsequent pte tables have to be allocated in one physical
40 * chunk of RAM.
41 */
42#define PKMAP_BASE (0xfe000000UL)
43#define LAST_PKMAP 1024
44#define LAST_PKMAP_MASK (LAST_PKMAP-1)
45#define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
46#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
47
48extern void * kmap_high(struct page *page);
49extern void kunmap_high(struct page *page);
50
51/*
52 * CONFIG_LIMITED_DMA is for systems with DMA limitations such as Momentum's
53 * Jaguar ATX. This option exploits the highmem code in the kernel so is
54 * always enabled together with CONFIG_HIGHMEM but at this time doesn't
55 * actually add highmem functionality.
56 */
57
58#ifdef CONFIG_LIMITED_DMA
59
60/*
61 * These are the default functions for the no-highmem case from
62 * <linux/highmem.h>
63 */
64static inline void *kmap(struct page *page)
65{
66 might_sleep();
67 return page_address(page);
68}
69
70#define kunmap(page) do { (void) (page); } while (0)
71
72static inline void *kmap_atomic(struct page *page, enum km_type type)
73{
74 return page_address(page);
75}
76
77static inline void kunmap_atomic(void *kvaddr, enum km_type type) { }
78#define kmap_atomic_pfn(pfn, idx) page_address(pfn_to_page(pfn))
79
80#define kmap_atomic_to_page(ptr) virt_to_page(ptr)
81
82#define flush_cache_kmaps() do { } while (0)
83
84#else /* LIMITED_DMA */
85
86extern void *__kmap(struct page *page);
87extern void __kunmap(struct page *page);
88extern void *__kmap_atomic(struct page *page, enum km_type type);
89extern void __kunmap_atomic(void *kvaddr, enum km_type type);
90extern void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
91extern struct page *__kmap_atomic_to_page(void *ptr);
92
93#define kmap __kmap
94#define kunmap __kunmap
95#define kmap_atomic __kmap_atomic
96#define kunmap_atomic __kunmap_atomic
97#define kmap_atomic_to_page __kmap_atomic_to_page
98
99#define flush_cache_kmaps() flush_cache_all()
100
101#endif /* LIMITED_DMA */
102
103#endif /* __KERNEL__ */
104
105#endif /* _ASM_HIGHMEM_H */