// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2014 Imagination Technologies Ltd.
 *
 * CPU PM notifiers for saving/restoring general CPU state.
 */

#include <linux/cpu_pm.h>
#include <linux/init.h>

#include <asm/dsp.h>
#include <asm/fpu.h>
#include <asm/mmu_context.h>
#include <asm/pm.h>
#include <asm/watch.h>

/* Used by PM helper macros in asm/pm.h */
struct mips_static_suspend_state mips_static_suspend_state;

/**
 * mips_cpu_save() - Save general CPU state.
 * Ensures that general CPU context is saved, notably FPU and DSP.
 */
static int mips_cpu_save(void)
{
        /* Save FPU state */
        lose_fpu(1);

        /* Save DSP state */
        save_dsp(current);

        return 0;
}

/**
 * mips_cpu_restore() - Restore general CPU state.
 * Restores important CPU context.
 */
static void mips_cpu_restore(void)
{
        unsigned int cpu = smp_processor_id();

        /* Restore ASID */
        if (current->mm)
                write_c0_entryhi(cpu_asid(cpu, current->mm));

        /* Restore DSP state */
        restore_dsp(current);

        /* Restore UserLocal */
        if (cpu_has_userlocal)
                write_c0_userlocal(current_thread_info()->tp_value);

        /* Restore watch registers */
        __restore_watch(current);
}

/**
 * mips_pm_notifier() - Notifier for preserving general CPU context.
 * @self:       Notifier block.
 * @cmd:        CPU PM event.
 * @v:          Private data (unused).
 *
 * This is called when a CPU power management event occurs, and is used to
 * ensure that important CPU context is preserved across a CPU power down.
 */
static int mips_pm_notifier(struct notifier_block *self, unsigned long cmd,
                            void *v)
{
        int ret;

        switch (cmd) {
        case CPU_PM_ENTER:
                ret = mips_cpu_save();
                if (ret)
                        return NOTIFY_STOP;
                break;
        case CPU_PM_ENTER_FAILED:
        case CPU_PM_EXIT:
                mips_cpu_restore();
                break;
        }

        return NOTIFY_OK;
}

static struct notifier_block mips_pm_notifier_block = {
        .notifier_call = mips_pm_notifier,
};

static int __init mips_pm_init(void)
{
        return cpu_pm_register_notifier(&mips_pm_notifier_block);
}
arch_initcall(mips_pm_init);