85 lines
2.5 KiB
C
85 lines
2.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* OpenRISC Linux
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*
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* Linux architectural port borrowing liberally from similar works of
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* others. All original copyrights apply as per the original source
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* declaration.
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*
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* OpenRISC implementation:
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* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
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* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
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* et al.
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*/
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#ifndef __ASM_OPENRISC_FIXMAP_H
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#define __ASM_OPENRISC_FIXMAP_H
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/* Why exactly do we need 2 empty pages between the top of the fixed
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* addresses and the top of virtual memory? Something is using that
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* memory space but not sure what right now... If you find it, leave
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* a comment here.
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*/
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#define FIXADDR_TOP ((unsigned long) (-2*PAGE_SIZE))
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#include <linux/kernel.h>
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#include <linux/bug.h>
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#include <asm/page.h>
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/*
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* On OpenRISC we use these special fixed_addresses for doing ioremap
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* early in the boot process before memory initialization is complete.
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* This is used, in particular, by the early serial console code.
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*
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* It's not really 'fixmap', per se, but fits loosely into the same
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* paradigm.
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*/
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enum fixed_addresses {
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/*
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* FIX_IOREMAP entries are useful for mapping physical address
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* space before ioremap() is useable, e.g. really early in boot
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* before kmalloc() is working.
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*/
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#define FIX_N_IOREMAPS 32
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FIX_IOREMAP_BEGIN,
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FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
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__end_of_fixed_addresses
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};
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#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
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/* FIXADDR_BOTTOM might be a better name here... */
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#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
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#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
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#define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
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/*
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* 'index to address' translation. If anyone tries to use the idx
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* directly without tranlation, we catch the bug with a NULL-deference
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* kernel oops. Illegal ranges of incoming indices are caught too.
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*/
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static __always_inline unsigned long fix_to_virt(const unsigned int idx)
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{
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/*
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* this branch gets completely eliminated after inlining,
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* except when someone tries to use fixaddr indices in an
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* illegal way. (such as mixing up address types or using
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* out-of-range indices).
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*
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* If it doesn't get removed, the linker will complain
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* loudly with a reasonably clear error message..
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*/
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if (idx >= __end_of_fixed_addresses)
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BUG();
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return __fix_to_virt(idx);
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}
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static inline unsigned long virt_to_fix(const unsigned long vaddr)
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{
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BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
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return __virt_to_fix(vaddr);
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}
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#endif
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