LXR linux/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 */
  22struct 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 */
  28static 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 */
  43static 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(current);
  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 */
  71static 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
  91static struct notifier_block mips_pm_notifier_block = {
  92        .notifier_call = mips_pm_notifier,
  93};
  94
  95static int __init mips_pm_init(void)
  96{
  97        return cpu_pm_register_notifier(&mips_pm_notifier_block);
  98}
  99arch_initcall(mips_pm_init);
 100