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
18#ifndef _ASM_HIGHMEM_H
19#define _ASM_HIGHMEM_H
20
21#ifdef __KERNEL__
22
23#include <linux/init.h>
24#include <linux/interrupt.h>
25#include <asm/kmap_types.h>
26#include <asm/pgtable.h>
27
28/* undef for production */
29#define HIGHMEM_DEBUG 1
30
31/* declarations for highmem.c */
32extern unsigned long highstart_pfn, highend_pfn;
33
34extern pte_t *kmap_pte;
35extern pgprot_t kmap_prot;
36extern pte_t *pkmap_page_table;
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.
42 */
43#define PKMAP_BASE (0xfe000000UL)
44#define LAST_PKMAP 1024
45#define LAST_PKMAP_MASK (LAST_PKMAP-1)
46#define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
47#define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
48
49extern void * kmap_high(struct page *page);
50extern void kunmap_high(struct page *page);
51
52static inline void *kmap(struct page *page)
53{
54	if (in_interrupt())
55		out_of_line_bug();
56	if (page < highmem_start_page)
57		return page_address(page);
58	return kmap_high(page);
59}
60
61static inline void kunmap(struct page *page)
62{
63	if (in_interrupt())
64		out_of_line_bug();
65	if (page < highmem_start_page)
66		return;
67	kunmap_high(page);
68}
69
70/*
71 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
72 * gives a more generic (and caching) interface. But kmap_atomic can
73 * be used in IRQ contexts, so in some (very limited) cases we need
74 * it.
75 */
76static inline void *kmap_atomic(struct page *page, enum km_type type)
77{
78	enum fixed_addresses idx;
79	unsigned long vaddr;
80
81	if (page < highmem_start_page)
82		return page_address(page);
83
84	idx = type + KM_TYPE_NR*smp_processor_id();
85	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
86	set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
87	//local_flush_tlb_page(NULL, vaddr);
88	local_flush_tlb_all();
89
90	return (void*) vaddr;
91}
92
93static inline void kunmap_atomic(void *kvaddr, enum km_type type)
94{
95}
96
97#endif /* __KERNEL__ */
98
99#endif /* _ASM_HIGHMEM_H */
100