84 lines
2.0 KiB
C
84 lines
2.0 KiB
C
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/*
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* This file contains the routines for initializing the MMU
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* on the 8xx series of chips.
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* -- christophe
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*
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* Derived from arch/powerpc/mm/40x_mmu.c:
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <linux/memblock.h>
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#include "mmu_decl.h"
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extern int __map_without_ltlbs;
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/*
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* MMU_init_hw does the chip-specific initialization of the MMU hardware.
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*/
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void __init MMU_init_hw(void)
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{
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/* Nothing to do for the time being but keep it similar to other PPC */
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}
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#define LARGE_PAGE_SIZE_4M (1<<22)
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#define LARGE_PAGE_SIZE_8M (1<<23)
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#define LARGE_PAGE_SIZE_64M (1<<26)
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unsigned long __init mmu_mapin_ram(unsigned long top)
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{
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unsigned long v, s, mapped;
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phys_addr_t p;
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v = KERNELBASE;
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p = 0;
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s = top;
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if (__map_without_ltlbs)
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return 0;
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#ifdef CONFIG_PPC_4K_PAGES
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while (s >= LARGE_PAGE_SIZE_8M) {
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pmd_t *pmdp;
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unsigned long val = p | MD_PS8MEG;
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pmdp = pmd_offset(pud_offset(pgd_offset_k(v), v), v);
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*pmdp++ = __pmd(val);
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*pmdp++ = __pmd(val + LARGE_PAGE_SIZE_4M);
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v += LARGE_PAGE_SIZE_8M;
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p += LARGE_PAGE_SIZE_8M;
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s -= LARGE_PAGE_SIZE_8M;
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}
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#else /* CONFIG_PPC_16K_PAGES */
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while (s >= LARGE_PAGE_SIZE_64M) {
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pmd_t *pmdp;
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unsigned long val = p | MD_PS8MEG;
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pmdp = pmd_offset(pud_offset(pgd_offset_k(v), v), v);
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*pmdp++ = __pmd(val);
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v += LARGE_PAGE_SIZE_64M;
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p += LARGE_PAGE_SIZE_64M;
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s -= LARGE_PAGE_SIZE_64M;
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}
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#endif
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mapped = top - s;
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/* If the size of RAM is not an exact power of two, we may not
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* have covered RAM in its entirety with 8 MiB
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* pages. Consequently, restrict the top end of RAM currently
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* allocable so that calls to the MEMBLOCK to allocate PTEs for "tail"
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* coverage with normal-sized pages (or other reasons) do not
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* attempt to allocate outside the allowed range.
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*/
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memblock_set_current_limit(mapped);
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return mapped;
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}
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