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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * highmem.h: virtual kernel memory mappings for high memory
4 *
5 * Used in CONFIG_HIGHMEM systems for memory pages which
6 * are not addressable by direct kernel virtual addresses.
7 *
8 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
9 * Gerhard.Wichert@pdb.siemens.de
10 *
11 *
12 * Redesigned the x86 32-bit VM architecture to deal with
13 * up to 16 Terrabyte physical memory. With current x86 CPUs
14 * we now support up to 64 Gigabytes physical RAM.
15 *
16 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
17 */
18
19#ifndef _ASM_HIGHMEM_H
20#define _ASM_HIGHMEM_H
21
22#ifdef __KERNEL__
23
24#include <linux/interrupt.h>
25#include <linux/pgtable.h>
26#include <asm/vaddrs.h>
27#include <asm/kmap_types.h>
28#include <asm/pgtsrmmu.h>
29
30/* declarations for highmem.c */
31extern unsigned long highstart_pfn, highend_pfn;
32
33#define kmap_prot __pgprot(SRMMU_ET_PTE | SRMMU_PRIV | SRMMU_CACHE)
34extern pte_t *pkmap_page_table;
35
36void 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
54#define flush_cache_kmaps() flush_cache_all()
55
56#endif /* __KERNEL__ */
57
58#endif /* _ASM_HIGHMEM_H */