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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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74e9133519
Implement assembler helper macros in asm/pm.h for platform code to use for saving context across low power states - for example suspend to RAM or powered down cpuidle states. Macros are provided for saving and restoring the main CPU context used by C code and doing important configuration which must be done very early during resume. Notably EVA needs segmentation control registers to be restored before the stack or dynamically allocated memory is accessed, so that state is saved in global data. Signed-off-by: James Hogan <james.hogan@imgtec.com> Signed-off-by: Paul Burton <paul.burton@imgtec.com>
100 lines
2.2 KiB
C
100 lines
2.2 KiB
C
/*
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* Copyright (C) 2014 Imagination Technologies Ltd.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* CPU PM notifiers for saving/restoring general CPU state.
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*/
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#include <linux/cpu_pm.h>
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#include <linux/init.h>
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#include <asm/dsp.h>
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#include <asm/fpu.h>
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#include <asm/mmu_context.h>
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#include <asm/pm.h>
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#include <asm/watch.h>
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/* Used by PM helper macros in asm/pm.h */
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struct mips_static_suspend_state mips_static_suspend_state;
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/**
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* mips_cpu_save() - Save general CPU state.
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* Ensures that general CPU context is saved, notably FPU and DSP.
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*/
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static int mips_cpu_save(void)
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{
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/* Save FPU state */
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lose_fpu(1);
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/* Save DSP state */
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save_dsp(current);
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return 0;
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}
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/**
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* mips_cpu_restore() - Restore general CPU state.
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* Restores important CPU context.
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*/
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static void mips_cpu_restore(void)
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{
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unsigned int cpu = smp_processor_id();
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/* Restore ASID */
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if (current->mm)
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write_c0_entryhi(cpu_asid(cpu, current->mm));
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/* Restore DSP state */
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restore_dsp(current);
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/* Restore UserLocal */
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if (cpu_has_userlocal)
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write_c0_userlocal(current_thread_info()->tp_value);
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/* Restore watch registers */
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__restore_watch();
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}
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/**
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* mips_pm_notifier() - Notifier for preserving general CPU context.
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* @self: Notifier block.
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* @cmd: CPU PM event.
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* @v: Private data (unused).
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*
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* This is called when a CPU power management event occurs, and is used to
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* ensure that important CPU context is preserved across a CPU power down.
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*/
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static int mips_pm_notifier(struct notifier_block *self, unsigned long cmd,
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void *v)
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{
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int ret;
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switch (cmd) {
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case CPU_PM_ENTER:
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ret = mips_cpu_save();
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if (ret)
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return NOTIFY_STOP;
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break;
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case CPU_PM_ENTER_FAILED:
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case CPU_PM_EXIT:
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mips_cpu_restore();
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break;
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}
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return NOTIFY_OK;
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}
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static struct notifier_block mips_pm_notifier_block = {
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.notifier_call = mips_pm_notifier,
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};
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static int __init mips_pm_init(void)
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{
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return cpu_pm_register_notifier(&mips_pm_notifier_block);
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}
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arch_initcall(mips_pm_init);
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