fixmap.h

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/*
 * Copyright (C) 1998 Ingo Molnar
 * Copyright 2010 Tilera Corporation. All Rights Reserved.
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation, version 2.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 */

#ifndef _ASM_TILE_FIXMAP_H
#define _ASM_TILE_FIXMAP_H

#include <asm/page.h>

#ifndef __ASSEMBLY__
#include <linux/kernel.h>
#ifdef CONFIG_HIGHMEM
#include <linux/threads.h>
#include <asm/kmap_types.h>
#endif

#define __fix_to_virt(x)    (FIXADDR_TOP - ((x) << PAGE_SHIFT))
#define __virt_to_fix(x)    ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)

/*
 * 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 supervisor virtual memory 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
 * higher 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.
 */
enum fixed_addresses {
#ifdef __tilegx__
    /*
     * TILEPro has unmapped memory above so the hole isn't needed,
     * and in any case the hole pushes us over a single 16MB pmd.
     */
    FIX_HOLE,
#endif
#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
#ifdef __tilegx__  /* see homecache.c */
    FIX_HOMECACHE_BEGIN,
    FIX_HOMECACHE_END = FIX_HOMECACHE_BEGIN+(NR_CPUS)-1,
#endif
    __end_of_permanent_fixed_addresses,

    /*
     * Temporary boot-time mappings, used before ioremap() is functional.
     * Not currently needed by the Tile architecture.
     */
#define NR_FIX_BTMAPS   0
#if NR_FIX_BTMAPS
    FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
    FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS - 1,
    __end_of_fixed_addresses
#else
    __end_of_fixed_addresses = __end_of_permanent_fixed_addresses
#endif
};

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)
#define clear_fixmap(idx) \
        __set_fixmap(idx, 0, __pgprot(0))

#define __FIXADDR_SIZE  (__end_of_permanent_fixed_addresses << PAGE_SHIFT)
#define __FIXADDR_BOOT_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
#define FIXADDR_START       (FIXADDR_TOP + PAGE_SIZE - __FIXADDR_SIZE)
#define FIXADDR_BOOT_START  (FIXADDR_TOP + PAGE_SIZE - __FIXADDR_BOOT_SIZE)

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 __always_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);
}

static inline unsigned long virt_to_fix(const unsigned long vaddr)
{
    BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
    return __virt_to_fix(vaddr);
}

#endif /* !__ASSEMBLY__ */

#endif /* _ASM_TILE_FIXMAP_H */