1/*
  2 * highmem.h: virtual kernel memory mappings for high memory
  3 *
  4 * PowerPC version, stolen from the i386 version.
  5 *
  6 * Used in CONFIG_HIGHMEM systems for memory pages which
  7 * are not addressable by direct kernel virtual addresses.
  8 *
  9 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
 10 *		      Gerhard.Wichert@pdb.siemens.de
 11 *
 12 *
 13 * Redesigned the x86 32-bit VM architecture to deal with
 14 * up to 16 Terrabyte physical memory. With current x86 CPUs
 15 * we now support up to 64 Gigabytes physical RAM.
 16 *
 17 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
 18 */
 19
 20#ifndef _ASM_HIGHMEM_H
 21#define _ASM_HIGHMEM_H
 22
 23#ifdef __KERNEL__
 24
 25#include <linux/interrupt.h>
 26#include <asm/kmap_types.h>
 27#include <asm/tlbflush.h>
 28#include <asm/page.h>
 29#include <asm/fixmap.h>
 30
 31extern pte_t *kmap_pte;
 32extern pgprot_t kmap_prot;
 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
 61extern void *kmap_high(struct page *page);
 62extern void kunmap_high(struct page *page);
 63extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
 64extern void __kunmap_atomic(void *kvaddr);
 65
 66static inline void *kmap(struct page *page)
 67{
 68	might_sleep();
 69	if (!PageHighMem(page))
 70		return page_address(page);
 71	return kmap_high(page);
 72}
 73
 74static inline void kunmap(struct page *page)
 75{
 76	BUG_ON(in_interrupt());
 77	if (!PageHighMem(page))
 78		return;
 79	kunmap_high(page);
 80}
 81
 82static inline void *kmap_atomic(struct page *page)
 83{
 84	return kmap_atomic_prot(page, kmap_prot);
 85}
 86
 87static inline struct page *kmap_atomic_to_page(void *ptr)
 88{
 89	unsigned long idx, vaddr = (unsigned long) ptr;
 90	pte_t *pte;
 91
 92	if (vaddr < FIXADDR_START)
 93		return virt_to_page(ptr);
 94
 95	idx = virt_to_fix(vaddr);
 96	pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 97	return pte_page(*pte);
 98}
 99
100
101#define flush_cache_kmaps()	flush_cache_all()
102
103#endif /* __KERNEL__ */
104
105#endif /* _ASM_HIGHMEM_H */