1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2020 Western Digital Corporation or its affiliates.
4  */
5 
6 #include <linux/kernel.h>
7 #include <linux/mm.h>
8 #include <linux/sched.h>
9 #include <linux/err.h>
10 #include <linux/irq.h>
11 #include <linux/cpu.h>
12 #include <linux/sched/hotplug.h>
13 #include <asm/irq.h>
14 #include <asm/cpu_ops.h>
15 #include <asm/numa.h>
16 #include <asm/sbi.h>
17 
cpu_has_hotplug(unsigned int cpu)18 bool cpu_has_hotplug(unsigned int cpu)
19 {
20 	if (cpu_ops[cpu]->cpu_stop)
21 		return true;
22 
23 	return false;
24 }
25 
26 /*
27  * __cpu_disable runs on the processor to be shutdown.
28  */
__cpu_disable(void)29 int __cpu_disable(void)
30 {
31 	int ret = 0;
32 	unsigned int cpu = smp_processor_id();
33 
34 	if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_stop)
35 		return -EOPNOTSUPP;
36 
37 	if (cpu_ops[cpu]->cpu_disable)
38 		ret = cpu_ops[cpu]->cpu_disable(cpu);
39 
40 	if (ret)
41 		return ret;
42 
43 	remove_cpu_topology(cpu);
44 	numa_remove_cpu(cpu);
45 	set_cpu_online(cpu, false);
46 	irq_migrate_all_off_this_cpu();
47 
48 	return ret;
49 }
50 
51 /*
52  * Called on the thread which is asking for a CPU to be shutdown.
53  */
__cpu_die(unsigned int cpu)54 void __cpu_die(unsigned int cpu)
55 {
56 	int ret = 0;
57 
58 	if (!cpu_wait_death(cpu, 5)) {
59 		pr_err("CPU %u: didn't die\n", cpu);
60 		return;
61 	}
62 	pr_notice("CPU%u: off\n", cpu);
63 
64 	/* Verify from the firmware if the cpu is really stopped*/
65 	if (cpu_ops[cpu]->cpu_is_stopped)
66 		ret = cpu_ops[cpu]->cpu_is_stopped(cpu);
67 	if (ret)
68 		pr_warn("CPU%d may not have stopped: %d\n", cpu, ret);
69 }
70 
71 /*
72  * Called from the idle thread for the CPU which has been shutdown.
73  */
arch_cpu_idle_dead(void)74 void arch_cpu_idle_dead(void)
75 {
76 	idle_task_exit();
77 
78 	(void)cpu_report_death();
79 
80 	cpu_ops[smp_processor_id()]->cpu_stop();
81 	/* It should never reach here */
82 	BUG();
83 }
84