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