arch/mips/kernel/pm.c

   1 /*
   2  * Copyright (C) 2014 Imagination Technologies Ltd.
   3  *
   4  * This program is free software; you can redistribute  it and/or modify it
   5  * under  the terms of  the GNU General  Public License as published by the
   6  * Free Software Foundation;  either version 2 of the  License, or (at your
   7  * option) any later version.
   8  *
   9  * CPU PM notifiers for saving/restoring general CPU state.
  10  */
  11
  12 #include <linux/cpu_pm.h>
  13 #include <linux/init.h>
  14
  15 #include <asm/dsp.h>
  16 #include <asm/fpu.h>
  17 #include <asm/mmu_context.h>
  18 #include <asm/pm.h>
  19 #include <asm/watch.h>
  20
  21 /* Used by PM helper macros in asm/pm.h */
  22 struct mips_static_suspend_state mips_static_suspend_state;
  23
  24 /**
  25  * mips_cpu_save() - Save general CPU state.
  26  * Ensures that general CPU context is saved, notably FPU and DSP.
  27  */
  28 static int mips_cpu_save(void)
  29 {
  30         /* Save FPU state */
  31         lose_fpu(1);
  32
  33         /* Save DSP state */
  34         save_dsp(current);
  35
  36         return 0;
  37 }
  38
  39 /**
  40  * mips_cpu_restore() - Restore general CPU state.
  41  * Restores important CPU context.
  42  */
  43 static void mips_cpu_restore(void)
  44 {
  45         unsigned int cpu = smp_processor_id();
  46
  47         /* Restore ASID */
  48         if (current->mm)
  49                 write_c0_entryhi(cpu_asid(cpu, current->mm));
  50
  51         /* Restore DSP state */
  52         restore_dsp(current);
  53
  54         /* Restore UserLocal */
  55         if (cpu_has_userlocal)
  56                 write_c0_userlocal(current_thread_info()->tp_value);
  57
  58         /* Restore watch registers */
  59         __restore_watch();
  60 }
  61
  62 /**
  63  * mips_pm_notifier() - Notifier for preserving general CPU context.
  64  * @self:       Notifier block.
  65  * @cmd:        CPU PM event.
  66  * @v:          Private data (unused).
  67  *
  68  * This is called when a CPU power management event occurs, and is used to
  69  * ensure that important CPU context is preserved across a CPU power down.
  70  */
  71 static int mips_pm_notifier(struct notifier_block *self, unsigned long cmd,
  72                             void *v)
  73 {
  74         int ret;
  75
  76         switch (cmd) {
  77         case CPU_PM_ENTER:
  78                 ret = mips_cpu_save();
  79                 if (ret)
  80                         return NOTIFY_STOP;
  81                 break;
  82         case CPU_PM_ENTER_FAILED:
  83         case CPU_PM_EXIT:
  84                 mips_cpu_restore();
  85                 break;
  86         }
  87
  88         return NOTIFY_OK;
  89 }
  90
  91 static struct notifier_block mips_pm_notifier_block = {
  92         .notifier_call = mips_pm_notifier,
  93 };
  94
  95 static int __init mips_pm_init(void)
  96 {
  97         return cpu_pm_register_notifier(&mips_pm_notifier_block);
  98 }
  99 arch_initcall(mips_pm_init);