| 1 | |
| 2 | *
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| 3 | * fixmap.h: compile-time virtual memory allocation
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| 4 | *
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| 5 | * Copyright (C) 1998 Ingo Molnar
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| 6 | *
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| 7 | * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
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| 8 |
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| 9 |
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| 10 | #ifndef _ASM_FIXMAP_H
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| 11 | #define _ASM_FIXMAP_H
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| 12 |
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| 13 | #include <linux/kernel.h>
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| 14 | #include <linux/threads.h>
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| 15 | #include <asm/page.h>
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| 16 |
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| 17 | |
| 18 | * Here we define all the compile-time 'special' virtual
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| 19 | * addresses. The point is to have a constant address at
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| 20 | * compile time, but to set the physical address only
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| 21 | * in the boot process. We allocate these special addresses
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| 22 | * from the end of P3 backwards.
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| 23 | * Also this lets us do fail-safe vmalloc(), we
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| 24 | * can guarantee that these special addresses and
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| 25 | * vmalloc()-ed addresses never overlap.
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| 26 | *
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| 27 | * these 'compile-time allocated' memory buffers are
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| 28 | * fixed-size 4k pages. (or larger if used with an increment
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| 29 | * highger than 1) use fixmap_set(idx,phys) to associate
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| 30 | * physical memory with fixmap indices.
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| 31 | *
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| 32 | * TLB entries of such buffers will not be flushed across
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| 33 | * task switches.
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| 34 |
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| 35 |
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| 36 | |
| 37 | * on UP currently we will have no trace of the fixmap mechanizm,
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| 38 | * no page table allocations, etc. This might change in the
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| 39 | * future, say framebuffers for the console driver(s) could be
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| 40 | * fix-mapped?
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| 41 |
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| 42 | enum fixed_addresses {
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| 43 | |
| 44 | * The FIX_CMAP entries are used by kmap_coherent() to get virtual
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| 45 | * addresses which are of a known color, and so their values are
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| 46 | * important. __fix_to_virt(FIX_CMAP_END - n) must give an address
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| 47 | * which is the same color as a page (n<<PAGE_SHIFT).
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| 48 |
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| 49 | #define FIX_N_COLOURS 8
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| 50 | FIX_CMAP_BEGIN,
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| 51 | FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1,
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| 52 |
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| 53 | #ifdef CONFIG_IOREMAP_FIXED
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| 54 | |
| 55 | * FIX_IOREMAP entries are useful for mapping physical address
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| 56 | * space before ioremap() is useable, e.g. really early in boot
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| 57 | * before kmalloc() is working.
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| 58 |
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| 59 | #define FIX_N_IOREMAPS 32
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| 60 | FIX_IOREMAP_BEGIN,
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| 61 | FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
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| 62 | #endif
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| 63 |
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| 64 | __end_of_fixed_addresses
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| 65 | };
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| 66 |
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| 67 | extern void __set_fixmap(enum fixed_addresses idx,
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| 68 | unsigned long phys, pgprot_t flags);
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| 69 | extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags);
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| 70 |
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| 71 | |
| 72 | * used by vmalloc.c.
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| 73 | *
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| 74 | * Leave one empty page between vmalloc'ed areas and
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| 75 | * the start of the fixmap, and leave one page empty
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| 76 | * at the top of mem..
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| 77 |
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| 78 | #define FIXADDR_TOP (P4SEG - PAGE_SIZE)
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| 79 | #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
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| 80 | #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
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| 81 |
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| 82 | #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
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| 83 |
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| 84 | #include <asm-generic/fixmap.h>
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| 85 |
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| 86 | #endif
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