arch/mips/kernel/pm.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2014 Imagination Technologies Ltd.
   4  *
   5  * CPU PM notifiers for saving/restoring general CPU state.
   6  */
   7
   8 #include <linux/cpu_pm.h>
   9 #include <linux/init.h>
  10
  11 #include <asm/dsp.h>
  12 #include <asm/fpu.h>
  13 #include <asm/mmu_context.h>
  14 #include <asm/pm.h>
  15 #include <asm/watch.h>
  16
  17 /* Used by PM helper macros in asm/pm.h */
  18 struct mips_static_suspend_state mips_static_suspend_state;
  19
  20 /**
  21  * mips_cpu_save() - Save general CPU state.
  22  * Ensures that general CPU context is saved, notably FPU and DSP.
  23  */
  24 static int mips_cpu_save(void)
  25 {
  26         /* Save FPU state */
  27         lose_fpu(1);
  28
  29         /* Save DSP state */
  30         save_dsp(current);
  31
  32         return 0;
  33 }
  34
  35 /**
  36  * mips_cpu_restore() - Restore general CPU state.
  37  * Restores important CPU context.
  38  */
  39 static void mips_cpu_restore(void)
  40 {
  41         unsigned int cpu = smp_processor_id();
  42
  43         /* Restore ASID */
  44         if (current->mm)
  45                 write_c0_entryhi(cpu_asid(cpu, current->mm));
  46
  47         /* Restore DSP state */
  48         restore_dsp(current);
  49
  50         /* Restore UserLocal */
  51         if (cpu_has_userlocal)
  52                 write_c0_userlocal(current_thread_info()->tp_value);
  53
  54         /* Restore watch registers */
  55         __restore_watch(current);
  56 }
  57
  58 /**
  59  * mips_pm_notifier() - Notifier for preserving general CPU context.
  60  * @self:       Notifier block.
  61  * @cmd:        CPU PM event.
  62  * @v:          Private data (unused).
  63  *
  64  * This is called when a CPU power management event occurs, and is used to
  65  * ensure that important CPU context is preserved across a CPU power down.
  66  */
  67 static int mips_pm_notifier(struct notifier_block *self, unsigned long cmd,
  68                             void *v)
  69 {
  70         int ret;
  71
  72         switch (cmd) {
  73         case CPU_PM_ENTER:
  74                 ret = mips_cpu_save();
  75                 if (ret)
  76                         return NOTIFY_STOP;
  77                 break;
  78         case CPU_PM_ENTER_FAILED:
  79         case CPU_PM_EXIT:
  80                 mips_cpu_restore();
  81                 break;
  82         }
  83
  84         return NOTIFY_OK;
  85 }
  86
  87 static struct notifier_block mips_pm_notifier_block = {
  88         .notifier_call = mips_pm_notifier,
  89 };
  90
  91 static int __init mips_pm_init(void)
  92 {
  93         return cpu_pm_register_notifier(&mips_pm_notifier_block);
  94 }
  95 arch_initcall(mips_pm_init);