LXR linux/arch/metag/mm/mmu-meta1.c

   1/*
   2 *  Copyright (C) 2005,2006,2007,2008,2009 Imagination Technologies
   3 *
   4 * Meta 1 MMU handling code.
   5 *
   6 */
   7
   8#include <linux/sched.h>
   9#include <linux/mm.h>
  10#include <linux/io.h>
  11
  12#include <asm/mmu.h>
  13
  14#define DM3_BASE (LINSYSDIRECT_BASE + (MMCU_DIRECTMAPn_ADDR_SCALE * 3))
  15
  16/*
  17 * This contains the physical address of the top level 2k pgd table.
  18 */
  19static unsigned long mmu_base_phys;
  20
  21/*
  22 * Given a physical address, return a mapped virtual address that can be used
  23 * to access that location.
  24 * In practice, we use the DirectMap region to make this happen.
  25 */
  26static unsigned long map_addr(unsigned long phys)
  27{
  28        static unsigned long dm_base = 0xFFFFFFFF;
  29        int offset;
  30
  31        offset = phys - dm_base;
  32
  33        /* Are we in the current map range ? */
  34        if ((offset < 0) || (offset >= MMCU_DIRECTMAPn_ADDR_SCALE)) {
  35                /* Calculate new DM area */
  36                dm_base = phys & ~(MMCU_DIRECTMAPn_ADDR_SCALE - 1);
  37
  38                /* Actually map it in! */
  39                metag_out32(dm_base, MMCU_DIRECTMAP3_ADDR);
  40
  41                /* And calculate how far into that area our reference is */
  42                offset = phys - dm_base;
  43        }
  44
  45        return DM3_BASE + offset;
  46}
  47
  48/*
  49 * Return the physical address of the base of our pgd table.
  50 */
  51static inline unsigned long __get_mmu_base(void)
  52{
  53        unsigned long base_phys;
  54        unsigned int stride;
  55
  56        if (is_global_space(PAGE_OFFSET))
  57                stride = 4;
  58        else
  59                stride = hard_processor_id();   /* [0..3] */
  60
  61        base_phys = metag_in32(MMCU_TABLE_PHYS_ADDR);
  62        base_phys += (0x800 * stride);
  63
  64        return base_phys;
  65}
  66
  67/* Given a virtual address, return the virtual address of the relevant pgd */
  68static unsigned long pgd_entry_addr(unsigned long virt)
  69{
  70        unsigned long pgd_phys;
  71        unsigned long pgd_virt;
  72
  73        if (!mmu_base_phys)
  74                mmu_base_phys = __get_mmu_base();
  75
  76        /*
  77         * Are we trying to map a global address.  If so, then index
  78         * the global pgd table instead of our local one.
  79         */
  80        if (is_global_space(virt)) {
  81                /* Scale into 2gig map */
  82                virt &= ~0x80000000;
  83        }
  84
  85        /* Base of the pgd table plus our 4Meg entry, 4bytes each */
  86        pgd_phys = mmu_base_phys + ((virt >> PGDIR_SHIFT) * 4);
  87
  88        pgd_virt = map_addr(pgd_phys);
  89
  90        return pgd_virt;
  91}
  92
  93/* Given a virtual address, return the virtual address of the relevant pte */
  94static unsigned long pgtable_entry_addr(unsigned long virt)
  95{
  96        unsigned long pgtable_phys;
  97        unsigned long pgtable_virt, pte_virt;
  98
  99        /* Find the physical address of the 4MB page table*/
 100        pgtable_phys = metag_in32(pgd_entry_addr(virt)) & MMCU_ENTRY_ADDR_BITS;
 101
 102        /* Map it to a virtual address */
 103        pgtable_virt = map_addr(pgtable_phys);
 104
 105        /* And index into it for our pte */
 106        pte_virt = pgtable_virt + ((virt >> PAGE_SHIFT) & 0x3FF) * 4;
 107
 108        return pte_virt;
 109}
 110
 111unsigned long mmu_read_first_level_page(unsigned long vaddr)
 112{
 113        return metag_in32(pgd_entry_addr(vaddr));
 114}
 115
 116unsigned long mmu_read_second_level_page(unsigned long vaddr)
 117{
 118        return metag_in32(pgtable_entry_addr(vaddr));
 119}
 120
 121unsigned long mmu_get_base(void)
 122{
 123        static unsigned long __base;
 124
 125        /* Find the base of our MMU pgd table */
 126        if (!__base)
 127                __base = pgd_entry_addr(0);
 128
 129        return __base;
 130}
 131
 132void __init mmu_init(unsigned long mem_end)
 133{
 134        unsigned long entry, addr;
 135        pgd_t *p_swapper_pg_dir;
 136
 137        /*
 138         * Now copy over any MMU pgd entries already in the mmu page tables
 139         * over to our root init process (swapper_pg_dir) map.  This map is
 140         * then inherited by all other processes, which means all processes
 141         * inherit a map of the kernel space.
 142         */
 143        addr = PAGE_OFFSET;
 144        entry = pgd_index(PAGE_OFFSET);
 145        p_swapper_pg_dir = pgd_offset_k(0) + entry;
 146
 147        while (addr <= META_MEMORY_LIMIT) {
 148                unsigned long pgd_entry;
 149                /* copy over the current MMU value */
 150                pgd_entry = mmu_read_first_level_page(addr);
 151                pgd_val(*p_swapper_pg_dir) = pgd_entry;
 152
 153                p_swapper_pg_dir++;
 154                addr += PGDIR_SIZE;
 155                entry++;
 156        }
 157}
 158