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/*

 * fixmap.h: compile-time virtual memory allocation

 *

 * This file is subject to the terms and conditions of the GNU General Public

 * License.  See the file "COPYING" in the main directory of this archive

 * for more details.

 *

 * Copyright (C) 1998 Ingo Molnar

 *

 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999

 */

#ifndef _ASM_FIXMAP_H

#define _ASM_FIXMAP_H

#include <linux/config.h>

#include <linux/kernel.h>

#include <asm/page.h>

#ifdef CONFIG_HIGHMEM

#include <linux/threads.h>

#include <asm/kmap_types.h>

#endif

/*

 * Here we define all the compile-time 'special' virtual

 * addresses. The point is to have a constant address at

 * compile time, but to set the physical address only

 * in the boot process. We allocate these special  addresses

 * from the end of virtual memory (0xfffff000) backwards.

 * Also this lets us do fail-safe vmalloc(), we

 * can guarantee that these special addresses and

 * vmalloc()-ed addresses never overlap.

 *

 * these 'compile-time allocated' memory buffers are

 * fixed-size 4k pages. (or larger if used with an increment

 * highger than 1) use fixmap_set(idx,phys) to associate

 * physical memory with fixmap indices.

 *

 * TLB entries of such buffers will not be flushed across

 * task switches.

 */

/*

 * on UP currently we will have no trace of the fixmap mechanizm,

 * no page table allocations, etc. This might change in the

 * future, say framebuffers for the console driver(s) could be

 * fix-mapped?

 */

enum fixed_addresses {

#ifdef CONFIG_HIGHMEM

        FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */

        FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,

#endif

        __end_of_fixed_addresses

};

extern void __set_fixmap (enum fixed_addresses idx,

                                        unsigned long phys, pgprot_t flags);

#define set_fixmap(idx, phys) \

                __set_fixmap(idx, phys, PAGE_KERNEL)

/*

 * Some hardware wants to get fixmapped without caching.

 */

#define set_fixmap_nocache(idx, phys) \

                __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)

/*

 * used by vmalloc.c.

 *

 * Leave one empty page between vmalloc'ed areas and

 * the start of the fixmap, and leave one page empty

 * at the top of mem..

 */

#define FIXADDR_TOP     (0xffffe000UL)

#define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)

#define FIXADDR_START   (FIXADDR_TOP - FIXADDR_SIZE)

#define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))

extern void __this_fixmap_does_not_exist(void);

/*

 * 'index to address' translation. If anyone tries to use the idx

 * directly without tranlation, we catch the bug with a NULL-deference

 * kernel oops. Illegal ranges of incoming indices are caught too.

 */

static inline unsigned long fix_to_virt(const unsigned int idx)

{

        /*

         * this branch gets completely eliminated after inlining,

         * except when someone tries to use fixaddr indices in an

         * illegal way. (such as mixing up address types or using

         * out-of-range indices).

         *

         * If it doesn't get removed, the linker will complain

         * loudly with a reasonably clear error message..

         */

        if (idx >= __end_of_fixed_addresses)

                __this_fixmap_does_not_exist();

        return __fix_to_virt(idx);

}

#endif