#include <linux/init.h>
  
  #include <asm/pgalloc.h>
  #include <asm/pgtable.h>
  #include <asm/memory.h>
  #include <asm/suspend.h>
  #include <asm/tlbflush.h>
  
  static pgd_t *suspend_pgd;

  extern int __cpu_suspend(unsigned long, int (*)(unsigned long));

  extern void cpu_resume_mmu(void);

  
  /*

   * This is called by __cpu_suspend() to save the state, and do whatever
   * flushing is required to ensure that when the CPU goes to sleep we have
   * the necessary data available when the caches are not searched.
   */
  void __cpu_suspend_save(u32 *ptr, u32 ptrsz, u32 sp, u32 *save_ptr)
  {
  	*save_ptr = virt_to_phys(ptr);
  
  	/* This must correspond to the LDM in cpu_resume() assembly */
  	*ptr++ = virt_to_phys(suspend_pgd);
  	*ptr++ = sp;
  	*ptr++ = virt_to_phys(cpu_do_resume);
  
  	cpu_do_suspend(ptr);
  
  	flush_cache_all();

  	outer_clean_range(*save_ptr, *save_ptr + ptrsz);
  	outer_clean_range(virt_to_phys(save_ptr),
  			  virt_to_phys(save_ptr) + sizeof(*save_ptr));

  }
  
  /*

   * Hide the first two arguments to __cpu_suspend - these are an implementation
   * detail which platform code shouldn't have to know about.
   */
  int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
  {
  	struct mm_struct *mm = current->active_mm;
  	int ret;
  
  	if (!suspend_pgd)
  		return -EINVAL;
  
  	/*

  	 * Provide a temporary page table with an identity mapping for
  	 * the MMU-enable code, required for resuming.  On successful
  	 * resume (indicated by a zero return code), we need to switch
  	 * back to the correct page tables.

  	 */

  	ret = __cpu_suspend(arg, fn);

  	if (ret == 0) {
  		cpu_switch_mm(mm->pgd, mm);
  		local_flush_tlb_all();
  	}

  
  	return ret;
  }
  
  static int __init cpu_suspend_init(void)
  {
  	suspend_pgd = pgd_alloc(&init_mm);
  	if (suspend_pgd) {

  		unsigned long addr = virt_to_phys(cpu_resume_mmu);

  		identity_mapping_add(suspend_pgd, addr, addr + SECTION_SIZE);
  	}
  	return suspend_pgd ? 0 : -ENOMEM;
  }
  core_initcall(cpu_suspend_init);