1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0-or-later */
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * OpenRISC Linux
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Linux architectural port borrowing liberally from similar works of
6*4882a593Smuzhiyun * others. All original copyrights apply as per the original source
7*4882a593Smuzhiyun * declaration.
8*4882a593Smuzhiyun *
9*4882a593Smuzhiyun * OpenRISC implementation:
10*4882a593Smuzhiyun * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
11*4882a593Smuzhiyun * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
12*4882a593Smuzhiyun * et al.
13*4882a593Smuzhiyun */
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun #ifndef __ASM_OPENRISC_FIXMAP_H
16*4882a593Smuzhiyun #define __ASM_OPENRISC_FIXMAP_H
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun /* Why exactly do we need 2 empty pages between the top of the fixed
19*4882a593Smuzhiyun * addresses and the top of virtual memory? Something is using that
20*4882a593Smuzhiyun * memory space but not sure what right now... If you find it, leave
21*4882a593Smuzhiyun * a comment here.
22*4882a593Smuzhiyun */
23*4882a593Smuzhiyun #define FIXADDR_TOP ((unsigned long) (-2*PAGE_SIZE))
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun #include <linux/kernel.h>
26*4882a593Smuzhiyun #include <linux/bug.h>
27*4882a593Smuzhiyun #include <asm/page.h>
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun /*
30*4882a593Smuzhiyun * On OpenRISC we use these special fixed_addresses for doing ioremap
31*4882a593Smuzhiyun * early in the boot process before memory initialization is complete.
32*4882a593Smuzhiyun * This is used, in particular, by the early serial console code.
33*4882a593Smuzhiyun *
34*4882a593Smuzhiyun * It's not really 'fixmap', per se, but fits loosely into the same
35*4882a593Smuzhiyun * paradigm.
36*4882a593Smuzhiyun */
37*4882a593Smuzhiyun enum fixed_addresses {
38*4882a593Smuzhiyun /*
39*4882a593Smuzhiyun * FIX_IOREMAP entries are useful for mapping physical address
40*4882a593Smuzhiyun * space before ioremap() is useable, e.g. really early in boot
41*4882a593Smuzhiyun * before kmalloc() is working.
42*4882a593Smuzhiyun */
43*4882a593Smuzhiyun #define FIX_N_IOREMAPS 32
44*4882a593Smuzhiyun FIX_IOREMAP_BEGIN,
45*4882a593Smuzhiyun FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
46*4882a593Smuzhiyun __end_of_fixed_addresses
47*4882a593Smuzhiyun };
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
50*4882a593Smuzhiyun /* FIXADDR_BOTTOM might be a better name here... */
51*4882a593Smuzhiyun #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
52*4882a593Smuzhiyun
53*4882a593Smuzhiyun #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
54*4882a593Smuzhiyun #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
55*4882a593Smuzhiyun
56*4882a593Smuzhiyun /*
57*4882a593Smuzhiyun * 'index to address' translation. If anyone tries to use the idx
58*4882a593Smuzhiyun * directly without tranlation, we catch the bug with a NULL-deference
59*4882a593Smuzhiyun * kernel oops. Illegal ranges of incoming indices are caught too.
60*4882a593Smuzhiyun */
fix_to_virt(const unsigned int idx)61*4882a593Smuzhiyun static __always_inline unsigned long fix_to_virt(const unsigned int idx)
62*4882a593Smuzhiyun {
63*4882a593Smuzhiyun /*
64*4882a593Smuzhiyun * this branch gets completely eliminated after inlining,
65*4882a593Smuzhiyun * except when someone tries to use fixaddr indices in an
66*4882a593Smuzhiyun * illegal way. (such as mixing up address types or using
67*4882a593Smuzhiyun * out-of-range indices).
68*4882a593Smuzhiyun *
69*4882a593Smuzhiyun * If it doesn't get removed, the linker will complain
70*4882a593Smuzhiyun * loudly with a reasonably clear error message..
71*4882a593Smuzhiyun */
72*4882a593Smuzhiyun if (idx >= __end_of_fixed_addresses)
73*4882a593Smuzhiyun BUG();
74*4882a593Smuzhiyun
75*4882a593Smuzhiyun return __fix_to_virt(idx);
76*4882a593Smuzhiyun }
77*4882a593Smuzhiyun
virt_to_fix(const unsigned long vaddr)78*4882a593Smuzhiyun static inline unsigned long virt_to_fix(const unsigned long vaddr)
79*4882a593Smuzhiyun {
80*4882a593Smuzhiyun BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
81*4882a593Smuzhiyun return __virt_to_fix(vaddr);
82*4882a593Smuzhiyun }
83*4882a593Smuzhiyun
84*4882a593Smuzhiyun #endif
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