/*
* highmem.h: virtual kernel memory mappings for high memory
*
* Used in CONFIG_HIGHMEM systems for memory pages which
* are not addressable by direct kernel virtual addresses.
*
* Copyright (C) 1999 Gerhard Wichert, Siemens AG
* [email protected]
*
*
* Redesigned the x86 32-bit VM architecture to deal with
* up to 16 Terrabyte physical memory. With current x86 CPUs
* we now support up to 64 Gigabytes physical RAM.
*
* Copyright (C) 1999 Ingo Molnar <[email protected]>
*/

#ifndef _ASM_HIGHMEM_H
#define _ASM_HIGHMEM_H

#ifdef __KERNEL__

#include <linux/interrupt.h>
#include <asm/vaddrs.h>
#include <asm/kmap_types.h>
#include <asm/pgtable.h>

/* declarations for highmem.c */
extern unsigned long highstart_pfn, highend_pfn;

extern pgprot_t kmap_prot;
extern pte_t *pkmap_page_table;

extern void kmap_init(void) __init;

/*
* Right now we initialize only a single pte table. It can be extended
* easily, subsequent pte tables have to be allocated in one physical
* chunk of RAM. Currently the simplest way to do this is to align the
* pkmap region on a pagetable boundary (4MB).
*/
#define LAST_PKMAP 1024
#define PKMAP_SIZE (LAST_PKMAP << PAGE_SHIFT)
#define PKMAP_BASE PMD_ALIGN(SRMMU_NOCACHE_VADDR + (SRMMU_MAX_NOCACHE_PAGES << PAGE_SHIFT))

#define LAST_PKMAP_MASK (LAST_PKMAP - 1)
#define PKMAP_NR(virt) ((virt - PKMAP_BASE) >> PAGE_SHIFT)
#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))

#define PKMAP_END (PKMAP_ADDR(LAST_PKMAP))

extern void *kmap_high(struct page *page);
extern void kunmap_high(struct page *page);

static inline void *kmap(struct page *page)
{
BUG_ON(in_interrupt());
if (!PageHighMem(page))
return page_address(page);
return kmap_high(page);
}

static inline void kunmap(struct page *page)
{
BUG_ON(in_interrupt());
if (!PageHighMem(page))
return;
kunmap_high(page);
}

extern void *kmap_atomic(struct page *page);
extern void __kunmap_atomic(void *kvaddr);

#define flush_cache_kmaps() flush_cache_all()

#endif /* __KERNEL__ */

#endif /* _ASM_HIGHMEM_H */