87 lines
2.5 KiB
C
87 lines
2.5 KiB
C
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/* SPDX-License-Identifier: GPL-2.0
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*
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* fixmap.h: compile-time virtual memory allocation
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*
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* Copyright (C) 1998 Ingo Molnar
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*
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* Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
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*/
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#ifndef _ASM_FIXMAP_H
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#define _ASM_FIXMAP_H
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#include <linux/kernel.h>
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#include <linux/threads.h>
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#include <asm/page.h>
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/*
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* Here we define all the compile-time 'special' virtual
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* addresses. The point is to have a constant address at
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* compile time, but to set the physical address only
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* in the boot process. We allocate these special addresses
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* from the end of P3 backwards.
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* Also this lets us do fail-safe vmalloc(), we
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* can guarantee that these special addresses and
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* vmalloc()-ed addresses never overlap.
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*
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* these 'compile-time allocated' memory buffers are
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* fixed-size 4k pages. (or larger if used with an increment
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* highger than 1) use fixmap_set(idx,phys) to associate
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* physical memory with fixmap indices.
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*
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* TLB entries of such buffers will not be flushed across
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* task switches.
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*/
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/*
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* on UP currently we will have no trace of the fixmap mechanizm,
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* no page table allocations, etc. This might change in the
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* future, say framebuffers for the console driver(s) could be
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* fix-mapped?
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*/
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enum fixed_addresses {
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/*
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* The FIX_CMAP entries are used by kmap_coherent() to get virtual
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* addresses which are of a known color, and so their values are
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* important. __fix_to_virt(FIX_CMAP_END - n) must give an address
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* which is the same color as a page (n<<PAGE_SHIFT).
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*/
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#define FIX_N_COLOURS 8
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FIX_CMAP_BEGIN,
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FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1,
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#ifdef CONFIG_IOREMAP_FIXED
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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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#endif
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__end_of_fixed_addresses
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};
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extern void __set_fixmap(enum fixed_addresses idx,
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unsigned long phys, pgprot_t flags);
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extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags);
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/*
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* used by vmalloc.c.
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*
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* Leave one empty page between vmalloc'ed areas and
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* the start of the fixmap, and leave one page empty
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* at the top of mem..
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*/
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#define FIXADDR_TOP (P4SEG - PAGE_SIZE)
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#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
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#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
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#define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
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#include <asm-generic/fixmap.h>
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#endif
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