1/*
2 * OpenRISC Linux
3 *
4 * Linux architectural port borrowing liberally from similar works of
5 * others.  All original copyrights apply as per the original source
6 * declaration.
7 *
8 * OpenRISC implementation:
9 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
11 * et al.
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
17 */
18
19#ifndef __ASM_OPENRISC_FIXMAP_H
20#define __ASM_OPENRISC_FIXMAP_H
21
22/* Why exactly do we need 2 empty pages between the top of the fixed
23 * addresses and the top of virtual memory?  Something is using that
24 * memory space but not sure what right now... If you find it, leave
25 * a comment here.
26 */
27#define FIXADDR_TOP	((unsigned long) (-2*PAGE_SIZE))
28
29#include <linux/kernel.h>
30#include <asm/page.h>
31
32/*
33 * On OpenRISC we use these special fixed_addresses for doing ioremap
34 * early in the boot process before memory initialization is complete.
35 * This is used, in particular, by the early serial console code.
36 *
37 * It's not really 'fixmap', per se, but fits loosely into the same
38 * paradigm.
39 */
40enum fixed_addresses {
41	/*
42	 * FIX_IOREMAP entries are useful for mapping physical address
43	 * space before ioremap() is useable, e.g. really early in boot
44	 * before kmalloc() is working.
45	 */
46#define FIX_N_IOREMAPS  32
47	FIX_IOREMAP_BEGIN,
48	FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
49	__end_of_fixed_addresses
50};
51
52#define FIXADDR_SIZE		(__end_of_fixed_addresses << PAGE_SHIFT)
53/* FIXADDR_BOTTOM might be a better name here... */
54#define FIXADDR_START		(FIXADDR_TOP - FIXADDR_SIZE)
55
56#define __fix_to_virt(x)	(FIXADDR_TOP - ((x) << PAGE_SHIFT))
57#define __virt_to_fix(x)	((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
58
59/*
60 * 'index to address' translation. If anyone tries to use the idx
61 * directly without tranlation, we catch the bug with a NULL-deference
62 * kernel oops. Illegal ranges of incoming indices are caught too.
63 */
64static __always_inline unsigned long fix_to_virt(const unsigned int idx)
65{
66	/*
67	 * this branch gets completely eliminated after inlining,
68	 * except when someone tries to use fixaddr indices in an
69	 * illegal way. (such as mixing up address types or using
70	 * out-of-range indices).
71	 *
72	 * If it doesn't get removed, the linker will complain
73	 * loudly with a reasonably clear error message..
74	 */
75	if (idx >= __end_of_fixed_addresses)
76		BUG();
77
78	return __fix_to_virt(idx);
79}
80
81static inline unsigned long virt_to_fix(const unsigned long vaddr)
82{
83	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
84	return __virt_to_fix(vaddr);
85}
86
87#endif
88