// 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, };