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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2020 Western Digital Corporation or its affiliates.
*/
#include <linux/errno.h>
#include <linux/of.h>
#include <linux/string.h>
#include <asm/cpu_ops.h>
#include <asm/sbi.h>
#include <asm/smp.h>
const struct cpu_operations cpu_ops_spinwait;
static int spinwait_cpu_prepare(unsigned int cpuid)
{
if (!cpu_ops_spinwait.cpu_start) {
pr_err("cpu start method not defined for CPU [%d]\n", cpuid);
return -ENODEV;
}
return 0;
}
static int spinwait_cpu_start(unsigned int cpuid, struct task_struct *tidle)
{
/*
* In this protocol, all cpus boot on their own accord. _start
* selects the first cpu to boot the kernel and causes the remainder
* of the cpus to spin in a loop waiting for their stack pointer to be
* setup by that main cpu. Writing to bootdata
* (i.e __cpu_up_stack_pointer) signals to the spinning cpus that they
* can continue the boot process.
*/
cpu_update_secondary_bootdata(cpuid, tidle);
return 0;
}
const struct cpu_operations cpu_ops_spinwait = {
.name = "spinwait",
.cpu_prepare = spinwait_cpu_prepare,
.cpu_start = spinwait_cpu_start,
};
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