/*
   * Copyright (C) 2006 Hollis Blanchard <hollisb@us.ibm.com>, IBM Corporation
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
   */
  
  #include <linux/mm.h>
  
  static unsigned long kernel_virtual_offset;

  static int is_xencomm_initialized;
  
  /* for xen early printk. It uses console io hypercall which uses xencomm.
   * However early printk may use it before xencomm initialization.
   */
  int
  xencomm_is_initialized(void)
  {
  	return is_xencomm_initialized;
  }

  
  void
  xencomm_initialize(void)
  {
  	kernel_virtual_offset = KERNEL_START - ia64_tpa(KERNEL_START);

  	is_xencomm_initialized = 1;

  }
  
  /* Translate virtual address to physical address.  */
  unsigned long
  xencomm_vtop(unsigned long vaddr)
  {
  	struct page *page;
  	struct vm_area_struct *vma;
  
  	if (vaddr == 0)
  		return 0UL;
  
  	if (REGION_NUMBER(vaddr) == 5) {
  		pgd_t *pgd;
  		pud_t *pud;
  		pmd_t *pmd;
  		pte_t *ptep;
  
  		/* On ia64, TASK_SIZE refers to current.  It is not initialized
  		   during boot.
  		   Furthermore the kernel is relocatable and __pa() doesn't
  		   work on  addresses.  */
  		if (vaddr >= KERNEL_START
  		    && vaddr < (KERNEL_START + KERNEL_TR_PAGE_SIZE))
  			return vaddr - kernel_virtual_offset;
  
  		/* In kernel area -- virtually mapped.  */
  		pgd = pgd_offset_k(vaddr);
  		if (pgd_none(*pgd) || pgd_bad(*pgd))
  			return ~0UL;
  
  		pud = pud_offset(pgd, vaddr);
  		if (pud_none(*pud) || pud_bad(*pud))
  			return ~0UL;
  
  		pmd = pmd_offset(pud, vaddr);
  		if (pmd_none(*pmd) || pmd_bad(*pmd))
  			return ~0UL;
  
  		ptep = pte_offset_kernel(pmd, vaddr);
  		if (!ptep)
  			return ~0UL;
  
  		return (pte_val(*ptep) & _PFN_MASK) | (vaddr & ~PAGE_MASK);
  	}
  
  	if (vaddr > TASK_SIZE) {
  		/* percpu variables */
  		if (REGION_NUMBER(vaddr) == 7 &&
  		    REGION_OFFSET(vaddr) >= (1ULL << IA64_MAX_PHYS_BITS))
  			ia64_tpa(vaddr);
  
  		/* kernel address */
  		return __pa(vaddr);
  	}
  
  	/* XXX double-check (lack of) locking */
  	vma = find_extend_vma(current->mm, vaddr);
  	if (!vma)
  		return ~0UL;
  
  	/* We assume the page is modified.  */
  	page = follow_page(vma, vaddr, FOLL_WRITE | FOLL_TOUCH);
  	if (!page)
  		return ~0UL;
  
  	return (page_to_pfn(page) << PAGE_SHIFT) | (vaddr & ~PAGE_MASK);
  }