arch/arm/kernel/suspend.c

   1 #include <linux/init.h>
   2
   3 #include <asm/pgalloc.h>
   4 #include <asm/pgtable.h>
   5 #include <asm/memory.h>
   6 #include <asm/suspend.h>
   7 #include <asm/tlbflush.h>
   8
   9 static pgd_t *suspend_pgd;
  10
  11 extern int __cpu_suspend(unsigned long, int (*)(unsigned long));
  12 extern void cpu_resume_mmu(void);
  13
  14 /*
  15  * This is called by __cpu_suspend() to save the state, and do whatever
  16  * flushing is required to ensure that when the CPU goes to sleep we have
  17  * the necessary data available when the caches are not searched.
  18  */
  19 void __cpu_suspend_save(u32 *ptr, u32 ptrsz, u32 sp, u32 *save_ptr)
  20 {
  21         *save_ptr = virt_to_phys(ptr);
  22
  23         /* This must correspond to the LDM in cpu_resume() assembly */
  24         *ptr++ = virt_to_phys(suspend_pgd);
  25         *ptr++ = sp;
  26         *ptr++ = virt_to_phys(cpu_do_resume);
  27
  28         cpu_do_suspend(ptr);
  29
  30         flush_cache_all();
  31         outer_clean_range(*save_ptr, *save_ptr + ptrsz);
  32         outer_clean_range(virt_to_phys(save_ptr),
  33                           virt_to_phys(save_ptr) + sizeof(*save_ptr));
  34 }
  35
  36 /*
  37  * Hide the first two arguments to __cpu_suspend - these are an implementation
  38  * detail which platform code shouldn't have to know about.
  39  */
  40 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
  41 {
  42         struct mm_struct *mm = current->active_mm;
  43         int ret;
  44
  45         if (!suspend_pgd)
  46                 return -EINVAL;
  47
  48         /*
  49          * Provide a temporary page table with an identity mapping for
  50          * the MMU-enable code, required for resuming.  On successful
  51          * resume (indicated by a zero return code), we need to switch
  52          * back to the correct page tables.
  53          */
  54         ret = __cpu_suspend(arg, fn);
  55         if (ret == 0) {
  56                 cpu_switch_mm(mm->pgd, mm);
  57                 local_flush_tlb_all();
  58         }
  59
  60         return ret;
  61 }
  62
  63 static int __init cpu_suspend_init(void)
  64 {
  65         suspend_pgd = pgd_alloc(&init_mm);
  66         if (suspend_pgd) {
  67                 unsigned long addr = virt_to_phys(cpu_resume_mmu);
  68                 identity_mapping_add(suspend_pgd, addr, addr + SECTION_SIZE);
  69         }
  70         return suspend_pgd ? 0 : -ENOMEM;
  71 }
  72 core_initcall(cpu_suspend_init);