linux/arch/riscv/kernel/cpu_ops.c
Atish Patra 2ffc48fc70
RISC-V: Move spinwait booting method to its own config
The spinwait booting method should only be used for platforms with older
firmware without SBI HSM extension or M-mode firmware because spinwait
method can't support cpu hotplug, kexec or sparse hartid. It is better
to move the entire spinwait implementation to its own config which can
be disabled if required. It is enabled by default to maintain backward
compatibility and M-mode Linux.

Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-01-20 09:27:16 -08:00

39 lines
888 B
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2020 Western Digital Corporation or its affiliates.
*/
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/of.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <asm/cpu_ops.h>
#include <asm/sbi.h>
#include <asm/smp.h>
const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
extern const struct cpu_operations cpu_ops_sbi;
#ifdef CONFIG_RISCV_BOOT_SPINWAIT
extern const struct cpu_operations cpu_ops_spinwait;
#else
const struct cpu_operations cpu_ops_spinwait = {
.name = "",
.cpu_prepare = NULL,
.cpu_start = NULL,
};
#endif
void __init cpu_set_ops(int cpuid)
{
#if IS_ENABLED(CONFIG_RISCV_SBI)
if (sbi_probe_extension(SBI_EXT_HSM) > 0) {
if (!cpuid)
pr_info("SBI HSM extension detected\n");
cpu_ops[cpuid] = &cpu_ops_sbi;
} else
#endif
cpu_ops[cpuid] = &cpu_ops_spinwait;
}