1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * highmem.h: virtual kernel memory mappings for high memory
4 *
5 * PowerPC version, stolen from the i386 version.
6 *
7 * Used in CONFIG_HIGHMEM systems for memory pages which
8 * are not addressable by direct kernel virtual addresses.
9 *
10 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
11 *		      Gerhard.Wichert@pdb.siemens.de
12 *
13 *
14 * Redesigned the x86 32-bit VM architecture to deal with
15 * up to 16 Terrabyte physical memory. With current x86 CPUs
16 * we now support up to 64 Gigabytes physical RAM.
17 *
18 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
19 */
20
21#ifndef _ASM_HIGHMEM_H
22#define _ASM_HIGHMEM_H
23
24#ifdef __KERNEL__
25
26#include <linux/interrupt.h>
27#include <asm/kmap_types.h>
28#include <asm/cacheflush.h>
29#include <asm/page.h>
30#include <asm/fixmap.h>
31
32extern pte_t *kmap_pte;
33extern pte_t *pkmap_page_table;
34
35/*
36 * Right now we initialize only a single pte table. It can be extended
37 * easily, subsequent pte tables have to be allocated in one physical
38 * chunk of RAM.
39 */
40/*
41 * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
42 * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
43 * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
44 * in case of 16K/64K/256K page sizes.
45 */
46#ifdef CONFIG_PPC_4K_PAGES
47#define PKMAP_ORDER	PTE_SHIFT
48#else
49#define PKMAP_ORDER	9
50#endif
51#define LAST_PKMAP	(1 << PKMAP_ORDER)
52#ifndef CONFIG_PPC_4K_PAGES
53#define PKMAP_BASE	(FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1))
54#else
55#define PKMAP_BASE	((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
56#endif
57#define LAST_PKMAP_MASK	(LAST_PKMAP-1)
58#define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
59#define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
60
61#define flush_cache_kmaps()	flush_cache_all()
62
63#endif /* __KERNEL__ */
64
65#endif /* _ASM_HIGHMEM_H */
66