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Commit 831ccf79 authored by Mark Rutland's avatar Mark Rutland Committed by Catalin Marinas
Browse files

arm64: add PSCI CPU_OFF-based hotplug support 



This patch adds support for using PSCI CPU_OFF calls for CPU hotplug.
With this code it is possible to hot unplug CPUs with "psci" as their
boot-method, as long as there's an appropriate cpu_off function id
specified in the psci node.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 9327e2c6

arch/arm64/kernel/psci.c

+30 −0
Original line number Diff line number Diff line
@@ -256,11 +256,41 @@ static int cpu_psci_cpu_boot(unsigned int cpu) 
	return err;

}



#ifdef CONFIG_HOTPLUG_CPU

static int cpu_psci_cpu_disable(unsigned int cpu)

{

	/* Fail early if we don't have CPU_OFF support */

	if (!psci_ops.cpu_off)

		return -EOPNOTSUPP;

	return 0;

}



static void cpu_psci_cpu_die(unsigned int cpu)

{

	int ret;

	/*

	 * There are no known implementations of PSCI actually using the

	 * power state field, pass a sensible default for now.

	 */

	struct psci_power_state state = {

		.type = PSCI_POWER_STATE_TYPE_POWER_DOWN,

	};



	ret = psci_ops.cpu_off(state);



	pr_crit("psci: unable to power off CPU%u (%d)\n", cpu, ret);

}

#endif



const struct cpu_operations cpu_psci_ops = {

	.name		= "psci",

	.cpu_init	= cpu_psci_cpu_init,

	.cpu_prepare	= cpu_psci_cpu_prepare,

	.cpu_boot	= cpu_psci_cpu_boot,

#ifdef CONFIG_HOTPLUG_CPU

	.cpu_disable	= cpu_psci_cpu_disable,

	.cpu_die	= cpu_psci_cpu_die,

#endif

};



#endif