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motorola.c

/*
 * linux/arch/m68k/mm/motorola.c
 *
 * Routines specific to the Motorola MMU, originally from:
 * linux/arch/m68k/init.c
 * which are Copyright (C) 1995 Hamish Macdonald
 *
 * Moved 8/20/1999 Sam Creasey
 */

#include <linux/module.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/bootmem.h>

#include <asm/setup.h>
#include <asm/uaccess.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/system.h>
#include <asm/machdep.h>
#include <asm/io.h>
#include <asm/dma.h>
#ifdef CONFIG_ATARI
#include <asm/atari_stram.h>
#endif
#include <asm/sections.h>

#undef DEBUG

#ifndef mm_cachebits
/*
 * Bits to add to page descriptors for "normal" caching mode.
 * For 68020/030 this is 0.
 * For 68040, this is _PAGE_CACHE040 (cachable, copyback)
 */
unsigned long mm_cachebits;
EXPORT_SYMBOL(mm_cachebits);
#endif

/* size of memory already mapped in head.S */
#define INIT_MAPPED_SIZE      (4UL<<20)

extern unsigned long availmem;

static pte_t * __init kernel_page_table(void)
{
      pte_t *ptablep;

      ptablep = (pte_t *)alloc_bootmem_low_pages(PAGE_SIZE);

      clear_page(ptablep);
      __flush_page_to_ram(ptablep);
      flush_tlb_kernel_page(ptablep);
      nocache_page(ptablep);

      return ptablep;
}

static pmd_t *last_pgtable __initdata = NULL;
pmd_t *zero_pgtable __initdata = NULL;

static pmd_t * __init kernel_ptr_table(void)
{
      if (!last_pgtable) {
            unsigned long pmd, last;
            int i;

            /* Find the last ptr table that was used in head.S and
             * reuse the remaining space in that page for further
             * ptr tables.
             */
            last = (unsigned long)kernel_pg_dir;
            for (i = 0; i < PTRS_PER_PGD; i++) {
                  if (!pgd_present(kernel_pg_dir[i]))
                        continue;
                  pmd = __pgd_page(kernel_pg_dir[i]);
                  if (pmd > last)
                        last = pmd;
            }

            last_pgtable = (pmd_t *)last;
#ifdef DEBUG
            printk("kernel_ptr_init: %p\n", last_pgtable);
#endif
      }

      last_pgtable += PTRS_PER_PMD;
      if (((unsigned long)last_pgtable & ~PAGE_MASK) == 0) {
            last_pgtable = (pmd_t *)alloc_bootmem_low_pages(PAGE_SIZE);

            clear_page(last_pgtable);
            __flush_page_to_ram(last_pgtable);
            flush_tlb_kernel_page(last_pgtable);
            nocache_page(last_pgtable);
      }

      return last_pgtable;
}

static void __init map_node(int node)
{
#define PTRTREESIZE (256*1024)
#define ROOTTREESIZE (32*1024*1024)
      unsigned long physaddr, virtaddr, size;
      pgd_t *pgd_dir;
      pmd_t *pmd_dir;
      pte_t *pte_dir;

      size = m68k_memory[node].size;
      physaddr = m68k_memory[node].addr;
      virtaddr = (unsigned long)phys_to_virt(physaddr);
      physaddr |= m68k_supervisor_cachemode |
                _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_DIRTY;
      if (CPU_IS_040_OR_060)
            physaddr |= _PAGE_GLOBAL040;

      while (size > 0) {
#ifdef DEBUG
            if (!(virtaddr & (PTRTREESIZE-1)))
                  printk ("\npa=%#lx va=%#lx ", physaddr & PAGE_MASK,
                        virtaddr);
#endif
            pgd_dir = pgd_offset_k(virtaddr);
            if (virtaddr && CPU_IS_020_OR_030) {
                  if (!(virtaddr & (ROOTTREESIZE-1)) &&
                      size >= ROOTTREESIZE) {
#ifdef DEBUG
                        printk ("[very early term]");
#endif
                        pgd_val(*pgd_dir) = physaddr;
                        size -= ROOTTREESIZE;
                        virtaddr += ROOTTREESIZE;
                        physaddr += ROOTTREESIZE;
                        continue;
                  }
            }
            if (!pgd_present(*pgd_dir)) {
                  pmd_dir = kernel_ptr_table();
#ifdef DEBUG
                  printk ("[new pointer %p]", pmd_dir);
#endif
                  pgd_set(pgd_dir, pmd_dir);
            } else
                  pmd_dir = pmd_offset(pgd_dir, virtaddr);

            if (CPU_IS_020_OR_030) {
                  if (virtaddr) {
#ifdef DEBUG
                        printk ("[early term]");
#endif
                        pmd_dir->pmd[(virtaddr/PTRTREESIZE) & 15] = physaddr;
                        physaddr += PTRTREESIZE;
                  } else {
                        int i;
#ifdef DEBUG
                        printk ("[zero map]");
#endif
                        zero_pgtable = kernel_ptr_table();
                        pte_dir = (pte_t *)zero_pgtable;
                        pmd_dir->pmd[0] = virt_to_phys(pte_dir) |
                              _PAGE_TABLE | _PAGE_ACCESSED;
                        pte_val(*pte_dir++) = 0;
                        physaddr += PAGE_SIZE;
                        for (i = 1; i < 64; physaddr += PAGE_SIZE, i++)
                              pte_val(*pte_dir++) = physaddr;
                  }
                  size -= PTRTREESIZE;
                  virtaddr += PTRTREESIZE;
            } else {
                  if (!pmd_present(*pmd_dir)) {
#ifdef DEBUG
                        printk ("[new table]");
#endif
                        pte_dir = kernel_page_table();
                        pmd_set(pmd_dir, pte_dir);
                  }
                  pte_dir = pte_offset_kernel(pmd_dir, virtaddr);

                  if (virtaddr) {
                        if (!pte_present(*pte_dir))
                              pte_val(*pte_dir) = physaddr;
                  } else
                        pte_val(*pte_dir) = 0;
                  size -= PAGE_SIZE;
                  virtaddr += PAGE_SIZE;
                  physaddr += PAGE_SIZE;
            }

      }
#ifdef DEBUG
      printk("\n");
#endif
}

/*
 * paging_init() continues the virtual memory environment setup which
 * was begun by the code in arch/head.S.
 */
void __init paging_init(void)
{
      unsigned long zones_size[MAX_NR_ZONES] = { 0, };
      unsigned long min_addr, max_addr;
      unsigned long addr, size, end;
      int i;

#ifdef DEBUG
      printk ("start of paging_init (%p, %lx)\n", kernel_pg_dir, availmem);
#endif

      /* Fix the cache mode in the page descriptors for the 680[46]0.  */
      if (CPU_IS_040_OR_060) {
            int i;
#ifndef mm_cachebits
            mm_cachebits = _PAGE_CACHE040;
#endif
            for (i = 0; i < 16; i++)
                  pgprot_val(protection_map[i]) |= _PAGE_CACHE040;
      }

      min_addr = m68k_memory[0].addr;
      max_addr = min_addr + m68k_memory[0].size;
      for (i = 1; i < m68k_num_memory;) {
            if (m68k_memory[i].addr < min_addr) {
                  printk("Ignoring memory chunk at 0x%lx:0x%lx before the first chunk\n",
                        m68k_memory[i].addr, m68k_memory[i].size);
                  printk("Fix your bootloader or use a memfile to make use of this area!\n");
                  m68k_num_memory--;
                  memmove(m68k_memory + i, m68k_memory + i + 1,
                        (m68k_num_memory - i) * sizeof(struct mem_info));
                  continue;
            }
            addr = m68k_memory[i].addr + m68k_memory[i].size;
            if (addr > max_addr)
                  max_addr = addr;
            i++;
      }
      m68k_memoffset = min_addr - PAGE_OFFSET;
      m68k_virt_to_node_shift = fls(max_addr - min_addr - 1) - 6;

      module_fixup(NULL, __start_fixup, __stop_fixup);
      flush_icache();

      high_memory = phys_to_virt(max_addr);

      min_low_pfn = availmem >> PAGE_SHIFT;
      max_low_pfn = max_addr >> PAGE_SHIFT;

      for (i = 0; i < m68k_num_memory; i++) {
            addr = m68k_memory[i].addr;
            end = addr + m68k_memory[i].size;
            m68k_setup_node(i);
            availmem = PAGE_ALIGN(availmem);
            availmem += init_bootmem_node(NODE_DATA(i),
                                    availmem >> PAGE_SHIFT,
                                    addr >> PAGE_SHIFT,
                                    end >> PAGE_SHIFT);
      }

      /*
       * Map the physical memory available into the kernel virtual
       * address space. First initialize the bootmem allocator with
       * the memory we already mapped, so map_node() has something
       * to allocate.
       */
      addr = m68k_memory[0].addr;
      size = m68k_memory[0].size;
      free_bootmem_node(NODE_DATA(0), availmem, min(INIT_MAPPED_SIZE, size) - (availmem - addr));
      map_node(0);
      if (size > INIT_MAPPED_SIZE)
            free_bootmem_node(NODE_DATA(0), addr + INIT_MAPPED_SIZE, size - INIT_MAPPED_SIZE);

      for (i = 1; i < m68k_num_memory; i++)
            map_node(i);

      flush_tlb_all();

      /*
       * initialize the bad page table and bad page to point
       * to a couple of allocated pages
       */
      empty_zero_page = alloc_bootmem_pages(PAGE_SIZE);

      /*
       * Set up SFC/DFC registers
       */
      set_fs(KERNEL_DS);

#ifdef DEBUG
      printk ("before free_area_init\n");
#endif
      for (i = 0; i < m68k_num_memory; i++) {
            zones_size[ZONE_DMA] = m68k_memory[i].size >> PAGE_SHIFT;
            free_area_init_node(i, zones_size,
                            m68k_memory[i].addr >> PAGE_SHIFT, NULL);
      }
}

void free_initmem(void)
{
      unsigned long addr;

      addr = (unsigned long)__init_begin;
      for (; addr < (unsigned long)__init_end; addr += PAGE_SIZE) {
            virt_to_page(addr)->flags &= ~(1 << PG_reserved);
            init_page_count(virt_to_page(addr));
            free_page(addr);
            totalram_pages++;
      }
}



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