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/sbi.h> 16 17 void cpu_stop(void); 18 void arch_cpu_idle_dead(void) 19 { 20 cpu_stop(); 21 } 22 23 bool cpu_has_hotplug(unsigned int cpu) 24 { 25 if (cpu_ops[cpu]->cpu_stop) 26 return true; 27 28 return false; 29 } 30 31 /* 32 * __cpu_disable runs on the processor to be shutdown. 33 */ 34 int __cpu_disable(void) 35 { 36 int ret = 0; 37 unsigned int cpu = smp_processor_id(); 38 39 if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_stop) 40 return -EOPNOTSUPP; 41 42 if (cpu_ops[cpu]->cpu_disable) 43 ret = cpu_ops[cpu]->cpu_disable(cpu); 44 45 if (ret) 46 return ret; 47 48 remove_cpu_topology(cpu); 49 set_cpu_online(cpu, false); 50 irq_migrate_all_off_this_cpu(); 51 52 return ret; 53 } 54 55 /* 56 * Called on the thread which is asking for a CPU to be shutdown. 57 */ 58 void __cpu_die(unsigned int cpu) 59 { 60 int ret = 0; 61 62 if (!cpu_wait_death(cpu, 5)) { 63 pr_err("CPU %u: didn't die\n", cpu); 64 return; 65 } 66 pr_notice("CPU%u: off\n", cpu); 67 68 /* Verify from the firmware if the cpu is really stopped*/ 69 if (cpu_ops[cpu]->cpu_is_stopped) 70 ret = cpu_ops[cpu]->cpu_is_stopped(cpu); 71 if (ret) 72 pr_warn("CPU%d may not have stopped: %d\n", cpu, ret); 73 } 74 75 /* 76 * Called from the idle thread for the CPU which has been shutdown. 77 */ 78 void cpu_stop(void) 79 { 80 idle_task_exit(); 81 82 (void)cpu_report_death(); 83 84 cpu_ops[smp_processor_id()]->cpu_stop(); 85 /* It should never reach here */ 86 BUG(); 87 } 88