arch/riscv/kernel/cpu-hotplug.c

   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/cpuhotplug.h>
  12 #include <linux/cpu.h>
  13 #include <linux/sched/hotplug.h>
  14 #include <asm/irq.h>
  15 #include <asm/cpu_ops.h>
  16 #include <asm/numa.h>
  17 #include <asm/smp.h>
  18
  19 bool cpu_has_hotplug(unsigned int cpu)
  20 {
  21         if (cpu_ops->cpu_stop)
  22                 return true;
  23
  24         return false;
  25 }
  26
  27 /*
  28  * __cpu_disable runs on the processor to be shutdown.
  29  */
  30 int __cpu_disable(void)
  31 {
  32         unsigned int cpu = smp_processor_id();
  33
  34         if (!cpu_ops->cpu_stop)
  35                 return -EOPNOTSUPP;
  36
  37         remove_cpu_topology(cpu);
  38         numa_remove_cpu(cpu);
  39         set_cpu_online(cpu, false);
  40         riscv_ipi_disable();
  41         irq_migrate_all_off_this_cpu();
  42
  43         return 0;
  44 }
  45
  46 #ifdef CONFIG_HOTPLUG_CPU
  47 /*
  48  * Called on the thread which is asking for a CPU to be shutdown, if the
  49  * CPU reported dead to the hotplug core.
  50  */
  51 void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
  52 {
  53         int ret = 0;
  54
  55         pr_notice("CPU%u: off\n", cpu);
  56
  57         /* Verify from the firmware if the cpu is really stopped*/
  58         if (cpu_ops->cpu_is_stopped)
  59                 ret = cpu_ops->cpu_is_stopped(cpu);
  60         if (ret)
  61                 pr_warn("CPU%d may not have stopped: %d\n", cpu, ret);
  62 }
  63
  64 /*
  65  * Called from the idle thread for the CPU which has been shutdown.
  66  */
  67 void __noreturn arch_cpu_idle_dead(void)
  68 {
  69         idle_task_exit();
  70
  71         cpuhp_ap_report_dead();
  72
  73         cpu_ops->cpu_stop();
  74         /* It should never reach here */
  75         BUG();
  76 }
  77 #endif