text: /*
   *  This file contains the routines setting up the linux page tables.
   *
   * Copyright (C) 2008 Michal Simek
   * Copyright (C) 2008 PetaLogix
   *
   *    Copyright (C) 2007 Xilinx, Inc.  All rights reserved.
   *
   *  Derived from arch/ppc/mm/pgtable.c:
   *    -- paulus
   *
   *  Derived from arch/ppc/mm/init.c:
   *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   *
   *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
   *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
   *    Copyright (C) 1996 Paul Mackerras
   *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
   *
   *  Derived from "arch/i386/mm/init.c"
   *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   *
   *  This file is subject to the terms and conditions of the GNU General
   *  Public License.  See the file COPYING in the main directory of this
   *  archive for more details.
   *
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/vmalloc.h>
  #include <linux/init.h>
  
  #include <asm/pgtable.h>
  #include <asm/pgalloc.h>
  #include <linux/io.h>
  #include <asm/mmu.h>
  #include <asm/sections.h>
  #include <asm/fixmap.h>
  
  #define flush_HPTE(X, va, pg)	_tlbie(va)
  
  unsigned long ioremap_base;
  unsigned long ioremap_bot;
  EXPORT_SYMBOL(ioremap_bot);
  
  #ifndef CONFIG_SMP
  struct pgtable_cache_struct quicklists;
  #endif
  
  static void __iomem *__ioremap(phys_addr_t addr, unsigned long size,
  		unsigned long flags)
  {
  	unsigned long v, i;
  	phys_addr_t p;
  	int err;
  
  	/*
  	 * Choose an address to map it to.
  	 * Once the vmalloc system is running, we use it.
  	 * Before then, we use space going down from ioremap_base
  	 * (ioremap_bot records where we're up to).
  	 */
  	p = addr & PAGE_MASK;
  	size = PAGE_ALIGN(addr + size) - p;
  
  	/*
  	 * Don't allow anybody to remap normal RAM that we're using.
  	 * mem_init() sets high_memory so only do the check after that.
  	 *
  	 * However, allow remap of rootfs: TBD
  	 */
  	if (mem_init_done &&
  		p >= memory_start && p < virt_to_phys(high_memory) &&
  		!(p >= virt_to_phys((unsigned long)&__bss_stop) &&
  		p < virt_to_phys((unsigned long)__bss_stop))) {
  		printk(KERN_WARNING "__ioremap(): phys addr "PTE_FMT
  			" is RAM lr %pf\n", (unsigned long)p,
  			__builtin_return_address(0));
  		return NULL;
  	}
  
  	if (size == 0)
  		return NULL;
  
  	/*
  	 * Is it already mapped? If the whole area is mapped then we're
  	 * done, otherwise remap it since we want to keep the virt addrs for
  	 * each request contiguous.
  	 *
  	 * We make the assumption here that if the bottom and top
  	 * of the range we want are mapped then it's mapped to the
  	 * same virt address (and this is contiguous).
  	 *  -- Cort
  	 */
  
  	if (mem_init_done) {
  		struct vm_struct *area;
  		area = get_vm_area(size, VM_IOREMAP);
  		if (area == NULL)
  			return NULL;
  		v = (unsigned long) area->addr;
  	} else {
  		v = (ioremap_bot -= size);
  	}
  
  	if ((flags & _PAGE_PRESENT) == 0)
  		flags |= _PAGE_KERNEL;
  	if (flags & _PAGE_NO_CACHE)
  		flags |= _PAGE_GUARDED;
  
  	err = 0;
  	for (i = 0; i < size && err == 0; i += PAGE_SIZE)
  		err = map_page(v + i, p + i, flags);
  	if (err) {
  		if (mem_init_done)
  			vfree((void *)v);
  		return NULL;
  	}
  
  	return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
  }
  
  void __iomem *ioremap(phys_addr_t addr, unsigned long size)
  {
  	return __ioremap(addr, size, _PAGE_NO_CACHE);
  }
  EXPORT_SYMBOL(ioremap);
  
  void iounmap(void *addr)
  {
  	if (addr > high_memory && (unsigned long) addr < ioremap_bot)
  		vfree((void *) (PAGE_MASK & (unsigned long) addr));
  }
  EXPORT_SYMBOL(iounmap);
  
  
  int map_page(unsigned long va, phys_addr_t pa, int flags)
  {
  	pmd_t *pd;
  	pte_t *pg;
  	int err = -ENOMEM;
  	/* Use upper 10 bits of VA to index the first level map */
  	pd = pmd_offset(pgd_offset_k(va), va);
  	/* Use middle 10 bits of VA to index the second-level map */
  	pg = pte_alloc_kernel(pd, va); /* from powerpc - pgtable.c */
  	/* pg = pte_alloc_kernel(&init_mm, pd, va); */
  
  	if (pg != NULL) {
  		err = 0;
  		set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT,
  				__pgprot(flags)));
  		if (unlikely(mem_init_done))
  			flush_HPTE(0, va, pmd_val(*pd));
  			/* flush_HPTE(0, va, pg); */
  	}
  	return err;
  }
  
  /*
   * Map in all of physical memory starting at CONFIG_KERNEL_START.
   */
  void __init mapin_ram(void)
  {
  	unsigned long v, p, s, f;
  
  	v = CONFIG_KERNEL_START;
  	p = memory_start;
  	for (s = 0; s < lowmem_size; s += PAGE_SIZE) {
  		f = _PAGE_PRESENT | _PAGE_ACCESSED |
  				_PAGE_SHARED | _PAGE_HWEXEC;
  		if ((char *) v < _stext || (char *) v >= _etext)
  			f |= _PAGE_WRENABLE;
  		else
  			/* On the MicroBlaze, no user access
  			   forces R/W kernel access */
  			f |= _PAGE_USER;
  		map_page(v, p, f);
  		v += PAGE_SIZE;
  		p += PAGE_SIZE;
  	}
  }
  
  /* is x a power of 2? */
  #define is_power_of_2(x)	((x) != 0 && (((x) & ((x) - 1)) == 0))
  
  /* Scan the real Linux page tables and return a PTE pointer for
   * a virtual address in a context.
   * Returns true (1) if PTE was found, zero otherwise.  The pointer to
   * the PTE pointer is unmodified if PTE is not found.
   */
  static int get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep)
  {
  	pgd_t	*pgd;
  	pmd_t	*pmd;
  	pte_t	*pte;
  	int     retval = 0;
  
  	pgd = pgd_offset(mm, addr & PAGE_MASK);
  	if (pgd) {
  		pmd = pmd_offset(pgd, addr & PAGE_MASK);
  		if (pmd_present(*pmd)) {
  			pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
  			if (pte) {
  				retval = 1;
  				*ptep = pte;
  			}
  		}
  	}
  	return retval;
  }
  
  /* Find physical address for this virtual address.  Normally used by
   * I/O functions, but anyone can call it.
   */
  unsigned long iopa(unsigned long addr)
  {
  	unsigned long pa;
  
  	pte_t *pte;
  	struct mm_struct *mm;
  
  	/* Allow mapping of user addresses (within the thread)
  	 * for DMA if necessary.
  	 */
  	if (addr < TASK_SIZE)
  		mm = current->mm;
  	else
  		mm = &init_mm;
  
  	pa = 0;
  	if (get_pteptr(mm, addr, &pte))
  		pa = (pte_val(*pte) & PAGE_MASK) | (addr & ~PAGE_MASK);
  
  	return pa;
  }
  
  __init_refok pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
  		unsigned long address)
  {
  	pte_t *pte;
  	if (mem_init_done) {
  		pte = (pte_t *)__get_free_page(GFP_KERNEL |
  					__GFP_REPEAT | __GFP_ZERO);
  	} else {
  		pte = (pte_t *)early_get_page();
  		if (pte)
  			clear_page(pte);
  	}
  	return pte;
  }
  
  void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t flags)
  {
  	unsigned long address = __fix_to_virt(idx);
  
  	if (idx >= __end_of_fixed_addresses)
  		BUG();
  
  	map_page(address, phys, pgprot_val(flags));
  }
  