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   1 /*
   2  * Set up paging and the MMU.
   3  *
   4  * Copyright (C) 2000-2003, Axis Communications AB.
   5  *
   6  * Authors:   Bjorn Wesen <bjornw@axis.com>
   7  *            Tobias Anderberg <tobiasa@axis.com>, CRISv32 port.
   8  */
   9 #include <linux/mmzone.h>
  10 #include <linux/init.h>
  11 #include <linux/bootmem.h>
  12 #include <linux/mm.h>
  13 #include <asm/pgtable.h>
  14 #include <asm/page.h>
  15 #include <asm/types.h>
  16 #include <asm/mmu.h>
  17 #include <asm/io.h>
  18 #include <asm/mmu_context.h>
  19 #include <asm/arch/hwregs/asm/mmu_defs_asm.h>
  20 #include <asm/arch/hwregs/supp_reg.h>
  21
  22 extern void tlb_init(void);
  23
  24 /*
  25  * The kernel is already mapped with linear mapping at kseg_c so there's no
  26  * need to map it with a page table. However, head.S also temporarily mapped it
  27  * at kseg_4 thus the ksegs are set up again. Also clear the TLB and do various
  28  * other paging stuff.
  29  */
  30 void __init
  31 cris_mmu_init(void)
  32 {
  33         unsigned long mmu_config;
  34         unsigned long mmu_kbase_hi;
  35         unsigned long mmu_kbase_lo;
  36         unsigned short mmu_page_id;
  37
  38         /*
  39          * Make sure the current pgd table points to something sane, even if it
  40          * is most probably not used until the next switch_mm.
  41          */
  42         per_cpu(current_pgd, smp_processor_id()) = init_mm.pgd;
  43
  44 #ifdef CONFIG_SMP
  45         {
  46                 pgd_t **pgd;
  47                 pgd = (pgd_t**)&per_cpu(current_pgd, smp_processor_id());
  48                 SUPP_BANK_SEL(1);
  49                 SUPP_REG_WR(RW_MM_TLB_PGD, pgd);
  50                 SUPP_BANK_SEL(2);
  51                 SUPP_REG_WR(RW_MM_TLB_PGD, pgd);
  52         }
  53 #endif
  54
  55         /* Initialise the TLB. Function found in tlb.c. */
  56         tlb_init();
  57
  58         /* Enable exceptions and initialize the kernel segments. */
  59         mmu_config = ( REG_STATE(mmu, rw_mm_cfg, we, on)        |
  60                        REG_STATE(mmu, rw_mm_cfg, acc, on)       |
  61                        REG_STATE(mmu, rw_mm_cfg, ex, on)        |
  62                        REG_STATE(mmu, rw_mm_cfg, inv, on)       |
  63                        REG_STATE(mmu, rw_mm_cfg, seg_f, linear) |
  64                        REG_STATE(mmu, rw_mm_cfg, seg_e, linear) |
  65                        REG_STATE(mmu, rw_mm_cfg, seg_d, page)   |
  66                        REG_STATE(mmu, rw_mm_cfg, seg_c, linear) |
  67                        REG_STATE(mmu, rw_mm_cfg, seg_b, linear) |
  68 #ifndef CONFIG_ETRAXFS_SIM
  69                        REG_STATE(mmu, rw_mm_cfg, seg_a, page)   |
  70 #else
  71                        REG_STATE(mmu, rw_mm_cfg, seg_a, linear) |
  72 #endif
  73                        REG_STATE(mmu, rw_mm_cfg, seg_9, page)   |
  74                        REG_STATE(mmu, rw_mm_cfg, seg_8, page)   |
  75                        REG_STATE(mmu, rw_mm_cfg, seg_7, page)   |
  76                        REG_STATE(mmu, rw_mm_cfg, seg_6, page)   |
  77                        REG_STATE(mmu, rw_mm_cfg, seg_5, page)   |
  78                        REG_STATE(mmu, rw_mm_cfg, seg_4, page)   |
  79                        REG_STATE(mmu, rw_mm_cfg, seg_3, page)   |
  80                        REG_STATE(mmu, rw_mm_cfg, seg_2, page)   |
  81                        REG_STATE(mmu, rw_mm_cfg, seg_1, page)   |
  82                        REG_STATE(mmu, rw_mm_cfg, seg_0, page));
  83
  84         mmu_kbase_hi = ( REG_FIELD(mmu, rw_mm_kbase_hi, base_f, 0x0) |
  85                          REG_FIELD(mmu, rw_mm_kbase_hi, base_e, 0x8) |
  86                          REG_FIELD(mmu, rw_mm_kbase_hi, base_d, 0x0) |
  87 #ifndef CONFIG_ETRAXFS_SIM
  88                          REG_FIELD(mmu, rw_mm_kbase_hi, base_c, 0x4) |
  89 #else
  90                          REG_FIELD(mmu, rw_mm_kbase_hi, base_c, 0x0) |
  91 #endif
  92                          REG_FIELD(mmu, rw_mm_kbase_hi, base_b, 0xb) |
  93 #ifndef CONFIG_ETRAXFS_SIM
  94                          REG_FIELD(mmu, rw_mm_kbase_hi, base_a, 0x0) |
  95 #else
  96                          REG_FIELD(mmu, rw_mm_kbase_hi, base_a, 0xa) |
  97 #endif
  98                          REG_FIELD(mmu, rw_mm_kbase_hi, base_9, 0x0) |
  99                          REG_FIELD(mmu, rw_mm_kbase_hi, base_8, 0x0));
 100
 101         mmu_kbase_lo = ( REG_FIELD(mmu, rw_mm_kbase_lo, base_7, 0x0) |
 102                          REG_FIELD(mmu, rw_mm_kbase_lo, base_6, 0x0) |
 103                          REG_FIELD(mmu, rw_mm_kbase_lo, base_5, 0x0) |
 104                          REG_FIELD(mmu, rw_mm_kbase_lo, base_4, 0x0) |
 105                          REG_FIELD(mmu, rw_mm_kbase_lo, base_3, 0x0) |
 106                          REG_FIELD(mmu, rw_mm_kbase_lo, base_2, 0x0) |
 107                          REG_FIELD(mmu, rw_mm_kbase_lo, base_1, 0x0) |
 108                          REG_FIELD(mmu, rw_mm_kbase_lo, base_0, 0x0));
 109
 110         mmu_page_id = REG_FIELD(mmu, rw_mm_tlb_hi, pid, 0);
 111
 112         /* Update the instruction MMU. */
 113         SUPP_BANK_SEL(BANK_IM);
 114         SUPP_REG_WR(RW_MM_CFG, mmu_config);
 115         SUPP_REG_WR(RW_MM_KBASE_HI, mmu_kbase_hi);
 116         SUPP_REG_WR(RW_MM_KBASE_LO, mmu_kbase_lo);
 117         SUPP_REG_WR(RW_MM_TLB_HI, mmu_page_id);
 118
 119         /* Update the data MMU. */
 120         SUPP_BANK_SEL(BANK_DM);
 121         SUPP_REG_WR(RW_MM_CFG, mmu_config);
 122         SUPP_REG_WR(RW_MM_KBASE_HI, mmu_kbase_hi);
 123         SUPP_REG_WR(RW_MM_KBASE_LO, mmu_kbase_lo);
 124         SUPP_REG_WR(RW_MM_TLB_HI, mmu_page_id);
 125
 126         SPEC_REG_WR(SPEC_REG_PID, 0);
 127
 128         /*
 129          * The MMU has been enabled ever since head.S but just to make it
 130          * totally obvious enable it here as well.
 131          */
 132         SUPP_BANK_SEL(BANK_GC);
 133         SUPP_REG_WR(RW_GC_CFG, 0xf); /* IMMU, DMMU, ICache, DCache on */
 134 }
 135
 136 void __init
 137 paging_init(void)
 138 {
 139         int i;
 140         unsigned long zones_size[MAX_NR_ZONES];
 141
 142         printk("Setting up paging and the MMU.\n");
 143
 144         /* Clear out the init_mm.pgd that will contain the kernel's mappings. */
 145         for(i = 0; i < PTRS_PER_PGD; i++)
 146                 swapper_pg_dir[i] = __pgd(0);
 147
 148         cris_mmu_init();
 149
 150         /*
 151          * Initialize the bad page table and bad page to point to a couple of
 152          * allocated pages.
 153          */
 154         empty_zero_page = (unsigned long) alloc_bootmem_pages(PAGE_SIZE);
 155         memset((void *) empty_zero_page, 0, PAGE_SIZE);
 156
 157         /* All pages are DMA'able in Etrax, so put all in the DMA'able zone. */
 158         zones_size[0] = ((unsigned long) high_memory - PAGE_OFFSET) >> PAGE_SHIFT;
 159
 160         for (i = 1; i < MAX_NR_ZONES; i++)
 161                 zones_size[i] = 0;
 162
 163         /*
 164          * Use free_area_init_node instead of free_area_init, because it is
 165          * designed for systems where the DRAM starts at an address
 166          * substantially higher than 0, like us (we start at PAGE_OFFSET). This
 167          * saves space in the mem_map page array.
 168          */
 169         free_area_init_node(0, &contig_page_data, zones_size, PAGE_OFFSET >> PAGE_SHIFT, 0);
 170
 171         mem_map = contig_page_data.node_mem_map;
 172 }