LXR linux/arch/riscv/kernel/cpu_ops

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (c) 2020 Western Digital Corporation or its affiliates.
   4 */
   5
   6#include <linux/errno.h>
   7#include <linux/of.h>
   8#include <linux/string.h>
   9#include <asm/cpu_ops.h>
  10#include <asm/sbi.h>
  11#include <asm/smp.h>
  12
  13const struct cpu_operations cpu_ops_spinwait;
  14
  15static int spinwait_cpu_prepare(unsigned int cpuid)
  16{
  17        if (!cpu_ops_spinwait.cpu_start) {
  18                pr_err("cpu start method not defined for CPU [%d]\n", cpuid);
  19                return -ENODEV;
  20        }
  21        return 0;
  22}
  23
  24static int spinwait_cpu_start(unsigned int cpuid, struct task_struct *tidle)
  25{
  26        /*
  27         * In this protocol, all cpus boot on their own accord.  _start
  28         * selects the first cpu to boot the kernel and causes the remainder
  29         * of the cpus to spin in a loop waiting for their stack pointer to be
  30         * setup by that main cpu.  Writing to bootdata
  31         * (i.e __cpu_up_stack_pointer) signals to the spinning cpus that they
  32         * can continue the boot process.
  33         */
  34        cpu_update_secondary_bootdata(cpuid, tidle);
  35
  36        return 0;
  37}
  38
  39const struct cpu_operations cpu_ops_spinwait = {
  40        .name           = "spinwait",
  41        .cpu_prepare    = spinwait_cpu_prepare,
  42        .cpu_start      = spinwait_cpu_start,
  43};
  44