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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);
- sbi_ecall(0x09000003, 0, cpuid_to_hartid_map(cpuid), 0, 0, 0, 0, 0);
- 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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