Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 344eb010 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt
Browse files

powerpc/powernv: Add CPU hotplug support 



Unplugged CPU go into NAP mode in a loop until woken up

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 78b782cb

arch/powerpc/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -323,7 +323,7 @@ config SWIOTLB 


config HOTPLUG_CPU

	bool "Support for enabling/disabling CPUs"

	depends on SMP && HOTPLUG && EXPERIMENTAL && (PPC_PSERIES || PPC_PMAC)

	depends on SMP && HOTPLUG && EXPERIMENTAL && (PPC_PSERIES || PPC_PMAC || PPC_POWERNV)

	---help---

	  Say Y here to be able to disable and re-enable individual

	  CPUs at runtime on SMP machines.

arch/powerpc/platforms/powernv/smp.c

+77 −1
Original line number Diff line number Diff line
@@ -33,7 +33,14 @@ 


#include "powernv.h"



static void __devinit pnv_smp_setup_cpu(int cpu)

#ifdef DEBUG

#include <asm/udbg.h>

#define DBG(fmt...) udbg_printf(fmt)

#else

#define DBG(fmt...)

#endif



static void __cpuinit pnv_smp_setup_cpu(int cpu)

{

	if (cpu != boot_cpuid)

		xics_setup_cpu();
@@ -55,6 +62,67 @@ static int pnv_smp_cpu_bootable(unsigned int nr) 
	return 1;

}



#ifdef CONFIG_HOTPLUG_CPU



static int pnv_smp_cpu_disable(void)

{

	int cpu = smp_processor_id();



	/* This is identical to pSeries... might consolidate by

	 * moving migrate_irqs_away to a ppc_md with default to

	 * the generic fixup_irqs. --BenH.

	 */

	set_cpu_online(cpu, false);

	vdso_data->processorCount--;

	if (cpu == boot_cpuid)

		boot_cpuid = cpumask_any(cpu_online_mask);

	xics_migrate_irqs_away();

	return 0;

}



static void pnv_smp_cpu_kill_self(void)

{

	unsigned int cpu;



	/* If powersave_nap is enabled, use NAP mode, else just

	 * spin aimlessly

	 */

	if (!powersave_nap) {

		generic_mach_cpu_die();

		return;

	}



	/* Standard hot unplug procedure */

	local_irq_disable();

	idle_task_exit();

	current->active_mm = NULL; /* for sanity */

	cpu = smp_processor_id();

	DBG("CPU%d offline\n", cpu);

	generic_set_cpu_dead(cpu);

	smp_wmb();



	/* We don't want to take decrementer interrupts while we are offline,

	 * so clear LPCR:PECE1. We keep PECE2 enabled.

	 */

	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);

	while (!generic_check_cpu_restart(cpu)) {

		power7_idle();

		if (!generic_check_cpu_restart(cpu)) {

			DBG("CPU%d Unexpected exit while offline !\n", cpu);

			/* We may be getting an IPI, so we re-enable

			 * interrupts to process it, it will be ignored

			 * since we aren't online (hopefully)

			 */

			local_irq_enable();

			local_irq_disable();

		}

	}

	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);

	DBG("CPU%d coming online...\n", cpu);

}



#endif /* CONFIG_HOTPLUG_CPU */



static struct smp_ops_t pnv_smp_ops = {

	.message_pass	= smp_muxed_ipi_message_pass,

	.cause_ipi	= NULL,	/* Filled at runtime by xics_smp_probe() */
@@ -62,6 +130,10 @@ static struct smp_ops_t pnv_smp_ops = { 
	.kick_cpu	= smp_generic_kick_cpu,

	.setup_cpu	= pnv_smp_setup_cpu,

	.cpu_bootable	= pnv_smp_cpu_bootable,

#ifdef CONFIG_HOTPLUG_CPU

	.cpu_disable	= pnv_smp_cpu_disable,

	.cpu_die	= generic_cpu_die,

#endif /* CONFIG_HOTPLUG_CPU */

};



/* This is called very early during platform setup_arch */
@@ -80,4 +152,8 @@ void __init pnv_smp_init(void) 
		smp_ops->take_timebase = rtas_take_timebase;

	}

#endif /* CONFIG_PPC_RTAS */



#ifdef CONFIG_HOTPLUG_CPU

	ppc_md.cpu_die	= pnv_smp_cpu_kill_self;

#endif

}