cpu-hotplug.c
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2020 Western Digital Corporation or its affiliates.
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/err.h>
#include <linux/irq.h>
#include <linux/cpu.h>
#include <linux/sched/hotplug.h>
#include <asm/irq.h>
#include <asm/cpu_ops.h>
#include <asm/numa.h>
#include <asm/sbi.h>
void cpu_stop(void);
void arch_cpu_idle_dead(void)
{
cpu_stop();
}
bool cpu_has_hotplug(unsigned int cpu)
{
if (cpu_ops[cpu]->cpu_stop)
return true;
return false;
}
/*
* __cpu_disable runs on the processor to be shutdown.
*/
int __cpu_disable(void)
{
int ret = 0;
unsigned int cpu = smp_processor_id();
if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_stop)
return -EOPNOTSUPP;
if (cpu_ops[cpu]->cpu_disable)
ret = cpu_ops[cpu]->cpu_disable(cpu);
if (ret)
return ret;
remove_cpu_topology(cpu);
numa_remove_cpu(cpu);
set_cpu_online(cpu, false);
irq_migrate_all_off_this_cpu();
return ret;
}
/*
* Called on the thread which is asking for a CPU to be shutdown.
*/
void __cpu_die(unsigned int cpu)
{
int ret = 0;
if (!cpu_wait_death(cpu, 5)) {
pr_err("CPU %u: didn't die\n", cpu);
return;
}
pr_notice("CPU%u: off\n", cpu);
/* Verify from the firmware if the cpu is really stopped*/
if (cpu_ops[cpu]->cpu_is_stopped)
ret = cpu_ops[cpu]->cpu_is_stopped(cpu);
if (ret)
pr_warn("CPU%d may not have stopped: %d\n", cpu, ret);
}
/*
* Called from the idle thread for the CPU which has been shutdown.
*/
void cpu_stop(void)
{
idle_task_exit();
(void)cpu_report_death();
cpu_ops[smp_processor_id()]->cpu_stop();
/* It should never reach here */
BUG();
}