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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/riscv/kernel/cpu_ops_sbi.c
26442 views
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// SPDX-License-Identifier: GPL-2.0-only

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/*

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 * HSM extension and cpu_ops implementation.

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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/init.h>

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#include <linux/mm.h>

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#include <linux/sched/task_stack.h>

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#include <asm/cpu_ops.h>

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#include <asm/cpu_ops_sbi.h>

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#include <asm/sbi.h>

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#include <asm/smp.h>

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extern char secondary_start_sbi[];

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const struct cpu_operations cpu_ops_sbi;

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/*

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 * Ordered booting via HSM brings one cpu at a time. However, cpu hotplug can

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 * be invoked from multiple threads in parallel. Define an array of boot data

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 * to handle that.

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 */

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static struct sbi_hart_boot_data boot_data[NR_CPUS];

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static int sbi_hsm_hart_start(unsigned long hartid, unsigned long saddr,

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			      unsigned long priv)

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{

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	struct sbiret ret;

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	ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_START,

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			hartid, saddr, priv, 0, 0, 0);

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	if (ret.error)

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		return sbi_err_map_linux_errno(ret.error);

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	else

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		return 0;

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}

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#ifdef CONFIG_HOTPLUG_CPU

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static int sbi_hsm_hart_stop(void)

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{

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	struct sbiret ret;

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	ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STOP, 0, 0, 0, 0, 0, 0);

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	if (ret.error)

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		return sbi_err_map_linux_errno(ret.error);

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	else

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		return 0;

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}

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static int sbi_hsm_hart_get_status(unsigned long hartid)

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{

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	struct sbiret ret;

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	ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STATUS,

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			hartid, 0, 0, 0, 0, 0);

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	if (ret.error)

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		return sbi_err_map_linux_errno(ret.error);

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	else

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		return ret.value;

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}

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#endif

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static int sbi_cpu_start(unsigned int cpuid, struct task_struct *tidle)

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{

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	unsigned long boot_addr = __pa_symbol(secondary_start_sbi);

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	unsigned long hartid = cpuid_to_hartid_map(cpuid);

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	unsigned long hsm_data;

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	struct sbi_hart_boot_data *bdata = &boot_data[cpuid];

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	/* Make sure tidle is updated */

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	smp_mb();

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	bdata->task_ptr = tidle;

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	bdata->stack_ptr = task_pt_regs(tidle);

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	/* Make sure boot data is updated */

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	smp_mb();

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	hsm_data = __pa(bdata);

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	return sbi_hsm_hart_start(hartid, boot_addr, hsm_data);

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}

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#ifdef CONFIG_HOTPLUG_CPU

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static void sbi_cpu_stop(void)

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{

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	int ret;

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	ret = sbi_hsm_hart_stop();

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	pr_crit("Unable to stop the cpu %u (%d)\n", smp_processor_id(), ret);

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}

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static int sbi_cpu_is_stopped(unsigned int cpuid)

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{

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	int rc;

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	unsigned long hartid = cpuid_to_hartid_map(cpuid);

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	rc = sbi_hsm_hart_get_status(hartid);

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	if (rc == SBI_HSM_STATE_STOPPED)

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		return 0;

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	return rc;

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}

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#endif

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const struct cpu_operations cpu_ops_sbi = {

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	.cpu_start	= sbi_cpu_start,

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#ifdef CONFIG_HOTPLUG_CPU

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	.cpu_stop	= sbi_cpu_stop,

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	.cpu_is_stopped	= sbi_cpu_is_stopped,

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#endif

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};

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