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init.c

/*
 * Set up paging and the MMU.
 *
 * Copyright (C) 2000-2003, Axis Communications AB.
 *
 * Authors:   Bjorn Wesen <bjornw@axis.com>
 *            Tobias Anderberg <tobiasa@axis.com>, CRISv32 port.
 */
#include <linux/mmzone.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/mm.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/types.h>
#include <asm/mmu.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/arch/hwregs/asm/mmu_defs_asm.h>
#include <asm/arch/hwregs/supp_reg.h>

extern void tlb_init(void);

/*
 * The kernel is already mapped with linear mapping at kseg_c so there's no
 * need to map it with a page table. However, head.S also temporarily mapped it
 * at kseg_4 thus the ksegs are set up again. Also clear the TLB and do various
 * other paging stuff.
 */
void __init
cris_mmu_init(void)
{
      unsigned long mmu_config;
      unsigned long mmu_kbase_hi;
      unsigned long mmu_kbase_lo;
      unsigned short mmu_page_id;

      /*
       * Make sure the current pgd table points to something sane, even if it
       * is most probably not used until the next switch_mm.
       */
      per_cpu(current_pgd, smp_processor_id()) = init_mm.pgd;

#ifdef CONFIG_SMP
      {
            pgd_t **pgd;
            pgd = (pgd_t**)&per_cpu(current_pgd, smp_processor_id());
            SUPP_BANK_SEL(1);
            SUPP_REG_WR(RW_MM_TLB_PGD, pgd);
            SUPP_BANK_SEL(2);
            SUPP_REG_WR(RW_MM_TLB_PGD, pgd);
      }
#endif

      /* Initialise the TLB. Function found in tlb.c. */
      tlb_init();

      /* Enable exceptions and initialize the kernel segments. */
      mmu_config = ( REG_STATE(mmu, rw_mm_cfg, we, on)        |
                   REG_STATE(mmu, rw_mm_cfg, acc, on)       |
                   REG_STATE(mmu, rw_mm_cfg, ex, on)        |
                   REG_STATE(mmu, rw_mm_cfg, inv, on)       |
                   REG_STATE(mmu, rw_mm_cfg, seg_f, linear) |
                   REG_STATE(mmu, rw_mm_cfg, seg_e, linear) |
                   REG_STATE(mmu, rw_mm_cfg, seg_d, page)   |
                   REG_STATE(mmu, rw_mm_cfg, seg_c, linear) |
                   REG_STATE(mmu, rw_mm_cfg, seg_b, linear) |
#ifndef CONFIG_ETRAX_VCS_SIM
                       REG_STATE(mmu, rw_mm_cfg, seg_a, page)   |
#else
                   REG_STATE(mmu, rw_mm_cfg, seg_a, linear) |
#endif
                   REG_STATE(mmu, rw_mm_cfg, seg_9, page)   |
                   REG_STATE(mmu, rw_mm_cfg, seg_8, page)   |
                   REG_STATE(mmu, rw_mm_cfg, seg_7, page)   |
                   REG_STATE(mmu, rw_mm_cfg, seg_6, page)   |
                   REG_STATE(mmu, rw_mm_cfg, seg_5, page)   |
                   REG_STATE(mmu, rw_mm_cfg, seg_4, page)   |
                   REG_STATE(mmu, rw_mm_cfg, seg_3, page)   |
                   REG_STATE(mmu, rw_mm_cfg, seg_2, page)   |
                   REG_STATE(mmu, rw_mm_cfg, seg_1, page)   |
                   REG_STATE(mmu, rw_mm_cfg, seg_0, page));

      mmu_kbase_hi = ( REG_FIELD(mmu, rw_mm_kbase_hi, base_f, 0x0) |
                   REG_FIELD(mmu, rw_mm_kbase_hi, base_e, 0x8) |
                   REG_FIELD(mmu, rw_mm_kbase_hi, base_d, 0x0) |
                         REG_FIELD(mmu, rw_mm_kbase_hi, base_c, 0x4) |
                   REG_FIELD(mmu, rw_mm_kbase_hi, base_b, 0xb) |
#ifndef CONFIG_ETRAX_VCS_SIM
                   REG_FIELD(mmu, rw_mm_kbase_hi, base_a, 0x0) |
#else
                         REG_FIELD(mmu, rw_mm_kbase_hi, base_a, 0xa) |
#endif
                   REG_FIELD(mmu, rw_mm_kbase_hi, base_9, 0x0) |
                   REG_FIELD(mmu, rw_mm_kbase_hi, base_8, 0x0));

      mmu_kbase_lo = ( REG_FIELD(mmu, rw_mm_kbase_lo, base_7, 0x0) |
                   REG_FIELD(mmu, rw_mm_kbase_lo, base_6, 0x0) |
                   REG_FIELD(mmu, rw_mm_kbase_lo, base_5, 0x0) |
                   REG_FIELD(mmu, rw_mm_kbase_lo, base_4, 0x0) |
                   REG_FIELD(mmu, rw_mm_kbase_lo, base_3, 0x0) |
                   REG_FIELD(mmu, rw_mm_kbase_lo, base_2, 0x0) |
                   REG_FIELD(mmu, rw_mm_kbase_lo, base_1, 0x0) |
                   REG_FIELD(mmu, rw_mm_kbase_lo, base_0, 0x0));

      mmu_page_id = REG_FIELD(mmu, rw_mm_tlb_hi, pid, 0);

      /* Update the instruction MMU. */
      SUPP_BANK_SEL(BANK_IM);
      SUPP_REG_WR(RW_MM_CFG, mmu_config);
      SUPP_REG_WR(RW_MM_KBASE_HI, mmu_kbase_hi);
      SUPP_REG_WR(RW_MM_KBASE_LO, mmu_kbase_lo);
      SUPP_REG_WR(RW_MM_TLB_HI, mmu_page_id);

      /* Update the data MMU. */
      SUPP_BANK_SEL(BANK_DM);
      SUPP_REG_WR(RW_MM_CFG, mmu_config);
      SUPP_REG_WR(RW_MM_KBASE_HI, mmu_kbase_hi);
      SUPP_REG_WR(RW_MM_KBASE_LO, mmu_kbase_lo);
      SUPP_REG_WR(RW_MM_TLB_HI, mmu_page_id);

      SPEC_REG_WR(SPEC_REG_PID, 0);

      /*
       * The MMU has been enabled ever since head.S but just to make it
       * totally obvious enable it here as well.
       */
      SUPP_BANK_SEL(BANK_GC);
      SUPP_REG_WR(RW_GC_CFG, 0xf); /* IMMU, DMMU, ICache, DCache on */
}

void __init
paging_init(void)
{
      int i;
      unsigned long zones_size[MAX_NR_ZONES];

      printk("Setting up paging and the MMU.\n");

      /* Clear out the init_mm.pgd that will contain the kernel's mappings. */
      for(i = 0; i < PTRS_PER_PGD; i++)
            swapper_pg_dir[i] = __pgd(0);

      cris_mmu_init();

      /*
       * Initialize the bad page table and bad page to point to a couple of
       * allocated pages.
       */
      empty_zero_page = (unsigned long) alloc_bootmem_pages(PAGE_SIZE);
      memset((void *) empty_zero_page, 0, PAGE_SIZE);

      /* All pages are DMA'able in Etrax, so put all in the DMA'able zone. */
      zones_size[0] = ((unsigned long) high_memory - PAGE_OFFSET) >> PAGE_SHIFT;

      for (i = 1; i < MAX_NR_ZONES; i++)
            zones_size[i] = 0;

      /*
       * Use free_area_init_node instead of free_area_init, because it is
       * designed for systems where the DRAM starts at an address
       * substantially higher than 0, like us (we start at PAGE_OFFSET). This
       * saves space in the mem_map page array.
       */
      free_area_init_node(0, zones_size, PAGE_OFFSET >> PAGE_SHIFT, 0);

      mem_map = contig_page_data.node_mem_map;
}

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