text: /*
   * linux/arch/m68k/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/config.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>
  #ifdef CONFIG_BLK_DEV_RAM
  #include <linux/blk.h>
  #endif
  
  #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
  
  #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 = 0;
  #endif
  
  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((unsigned long) ptablep);
  	flush_tlb_kernel_page((unsigned long) ptablep);
  	nocache_page ((unsigned long)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
  	}
  
  	if (((unsigned long)(last_pgtable + PTRS_PER_PMD) & ~PAGE_MASK) == 0) {
  		last_pgtable = (pmd_t *)alloc_bootmem_low_pages(PAGE_SIZE);
  
  		clear_page(last_pgtable);
  		__flush_page_to_ram((unsigned long)last_pgtable);
  		flush_tlb_kernel_page((unsigned long)last_pgtable);
  		nocache_page((unsigned long)last_pgtable);
  	} else
  		last_pgtable += PTRS_PER_PMD;
  
  	return last_pgtable;
  }
  
  static unsigned long __init 
  map_chunk (unsigned long addr, long size)
  {
  #define PTRTREESIZE (256*1024)
  #define ROOTTREESIZE (32*1024*1024)
  	static unsigned long virtaddr = PAGE_OFFSET;
  	unsigned long physaddr;
  	pgd_t *pgd_dir;
  	pmd_t *pmd_dir;
  	pte_t *pte_dir;
  
  	physaddr = (addr | 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(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
  
  	return virtaddr;
  }
  
  extern unsigned long empty_bad_page_table;
  extern unsigned long empty_bad_page;
  
  /*
   * paging_init() continues the virtual memory environment setup which
   * was begun by the code in arch/head.S.
   */
  void __init paging_init(void)
  {
  	int chunk;
  	unsigned long mem_avail = 0;
  	unsigned long zones_size[3] = { 0, };
  
  #ifdef DEBUG
  	{
  		extern unsigned long availmem;
  		printk ("start of paging_init (%p, %lx, %lx, %lx)\n",
  			kernel_pg_dir, availmem, start_mem, end_mem);
  	}
  #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;
  	}
  
  	/*
  	 * Map the physical memory available into the kernel virtual
  	 * address space.  It may allocate some memory for page
  	 * tables and thus modify availmem.
  	 */
  
  	for (chunk = 0; chunk < m68k_num_memory; chunk++) {
  		mem_avail = map_chunk (m68k_memory[chunk].addr,
  				       m68k_memory[chunk].size);
  
  	}
  
  	flush_tlb_all();
  #ifdef DEBUG
  	printk ("memory available is %ldKB\n", mem_avail >> 10);
  	printk ("start_mem is %#lx\nvirtual_end is %#lx\n",
  		start_mem, end_mem);
  #endif
  
  	/*
  	 * initialize the bad page table and bad page to point
  	 * to a couple of allocated pages
  	 */
  	empty_bad_page_table = (unsigned long)alloc_bootmem_pages(PAGE_SIZE);
  	empty_bad_page = (unsigned long)alloc_bootmem_pages(PAGE_SIZE);
  	empty_zero_page = (unsigned long)alloc_bootmem_pages(PAGE_SIZE);
  	memset((void *)empty_zero_page, 0, PAGE_SIZE);
  
  	/*
  	 * Set up SFC/DFC registers (user data space)
  	 */
  	set_fs (USER_DS);
  
  #ifdef DEBUG
  	printk ("before free_area_init\n");
  #endif
  	zones_size[0] = (mach_max_dma_address < (unsigned long)high_memory ?
  			 (mach_max_dma_address+1) : (unsigned long)high_memory);
  	zones_size[1] = (unsigned long)high_memory - zones_size[0];
  
  	zones_size[0] = (zones_size[0] - PAGE_OFFSET) >> PAGE_SHIFT;
  	zones_size[1] >>= PAGE_SHIFT;
  
  	free_area_init(zones_size);
  }
  
  extern char __init_begin, __init_end;
  extern unsigned long totalram_pages;
  
  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);
  		set_page_count(virt_to_page(addr), 1);
  		free_page(addr);
  		totalram_pages++;
  	}
  }
  
  
  