1/*
  2 * Copyright (C) 1998 Ingo Molnar
  3 * Copyright 2010 Tilera Corporation. All Rights Reserved.
  4 *
  5 *   This program is free software; you can redistribute it and/or
  6 *   modify it under the terms of the GNU General Public License
  7 *   as published by the Free Software Foundation, version 2.
  8 *
  9 *   This program is distributed in the hope that it will be useful, but
 10 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 11 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 12 *   NON INFRINGEMENT.  See the GNU General Public License for
 13 *   more details.
 14 */
 15
 16#ifndef _ASM_TILE_FIXMAP_H
 17#define _ASM_TILE_FIXMAP_H
 18
 19#include <asm/page.h>
 20
 21#ifndef __ASSEMBLY__
 22#include <linux/kernel.h>
 23#ifdef CONFIG_HIGHMEM
 24#include <linux/threads.h>
 25#include <asm/kmap_types.h>
 26#endif
 27
 28#define __fix_to_virt(x)	(FIXADDR_TOP - ((x) << PAGE_SHIFT))
 29#define __virt_to_fix(x)	((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
 30
 31/*
 32 * Here we define all the compile-time 'special' virtual
 33 * addresses. The point is to have a constant address at
 34 * compile time, but to set the physical address only
 35 * in the boot process. We allocate these special addresses
 36 * from the end of supervisor virtual memory backwards.
 37 * Also this lets us do fail-safe vmalloc(), we
 38 * can guarantee that these special addresses and
 39 * vmalloc()-ed addresses never overlap.
 40 *
 41 * these 'compile-time allocated' memory buffers are
 42 * fixed-size 4k pages. (or larger if used with an increment
 43 * higher than 1) use fixmap_set(idx,phys) to associate
 44 * physical memory with fixmap indices.
 45 *
 46 * TLB entries of such buffers will not be flushed across
 47 * task switches.
 48 *
 49 * We don't bother with a FIX_HOLE since above the fixmaps
 50 * is unmapped memory in any case.
 51 */
 52enum fixed_addresses {
 53#ifdef CONFIG_HIGHMEM
 54	FIX_KMAP_BEGIN,	/* reserved pte's for temporary kernel mappings */
 55	FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
 56#endif
 57	__end_of_permanent_fixed_addresses,
 58
 59	/*
 60	 * Temporary boot-time mappings, used before ioremap() is functional.
 61	 * Not currently needed by the Tile architecture.
 62	 */
 63#define NR_FIX_BTMAPS	0
 64#if NR_FIX_BTMAPS
 65	FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
 66	FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS - 1,
 67	__end_of_fixed_addresses
 68#else
 69	__end_of_fixed_addresses = __end_of_permanent_fixed_addresses
 70#endif
 71};
 72
 73extern void __set_fixmap(enum fixed_addresses idx,
 74			 unsigned long phys, pgprot_t flags);
 75
 76#define set_fixmap(idx, phys) \
 77		__set_fixmap(idx, phys, PAGE_KERNEL)
 78#define clear_fixmap(idx) \
 79		__set_fixmap(idx, 0, __pgprot(0))
 80
 81#define __FIXADDR_SIZE	(__end_of_permanent_fixed_addresses << PAGE_SHIFT)
 82#define __FIXADDR_BOOT_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
 83#define FIXADDR_START		(FIXADDR_TOP + PAGE_SIZE - __FIXADDR_SIZE)
 84#define FIXADDR_BOOT_START	(FIXADDR_TOP + PAGE_SIZE - __FIXADDR_BOOT_SIZE)
 85
 86extern void __this_fixmap_does_not_exist(void);
 87
 88/*
 89 * 'index to address' translation. If anyone tries to use the idx
 90 * directly without tranlation, we catch the bug with a NULL-deference
 91 * kernel oops. Illegal ranges of incoming indices are caught too.
 92 */
 93static __always_inline unsigned long fix_to_virt(const unsigned int idx)
 94{
 95	/*
 96	 * this branch gets completely eliminated after inlining,
 97	 * except when someone tries to use fixaddr indices in an
 98	 * illegal way. (such as mixing up address types or using
 99	 * out-of-range indices).
100	 *
101	 * If it doesn't get removed, the linker will complain
102	 * loudly with a reasonably clear error message..
103	 */
104	if (idx >= __end_of_fixed_addresses)
105		__this_fixmap_does_not_exist();
106
107	return __fix_to_virt(idx);
108}
109
110static inline unsigned long virt_to_fix(const unsigned long vaddr)
111{
112	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
113	return __virt_to_fix(vaddr);
114}
115
116#endif /* !__ASSEMBLY__ */
117
118#endif /* _ASM_TILE_FIXMAP_H */