787047eea2
Writes to /sys/.../cpuX/online fail if we determine the platform doesn't support hotplug for that CPU. Furthermore, if the cpu_die op isn't specified the system hangs when we try to offline a CPU and it comes right back online unexpectedly. Let's figure this stuff out before we make the sysfs nodes so that the online file doesn't even exist if it isn't (at least sometimes) possible to hotplug the CPU. Add a new 'cpu_can_disable' op and repoint all 'cpu_disable' implementations at it because all implementers use the op to indicate if a CPU can be hotplugged or not in a static fashion. With PSCI we may need to add a 'cpu_disable' op so that the secure OS can be migrated off the CPU we're trying to hotplug. In this case, the 'cpu_can_disable' op will indicate that all CPUs are hotpluggable by returning true, but the 'cpu_disable' op will make a PSCI migration call and occasionally fail, denying the hotplug of a CPU. This shouldn't be any worse than x86 where we may indicate that all CPUs are hotpluggable but occasionally we can't offline a CPU due to check_irq_vectors_for_cpu_disable() failing to find a CPU to move vectors to. Cc: Mark Rutland <mark.rutland@arm.com> Cc: Nicolas Pitre <nico@linaro.org> Cc: Dave Martin <Dave.Martin@arm.com> Acked-by: Simon Horman <horms@verge.net.au> [shmobile portion] Tested-by: Simon Horman <horms@verge.net.au> Cc: Magnus Damm <magnus.damm@gmail.com> Cc: <linux-sh@vger.kernel.org> Tested-by: Tyler Baker <tyler.baker@linaro.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
39 lines
1,005 B
C
39 lines
1,005 B
C
/*
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* SMP support for R-Mobile / SH-Mobile
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*
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* Copyright (C) 2010 Magnus Damm
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* Copyright (C) 2011 Paul Mundt
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*
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* Based on vexpress, Copyright (C) 2002 ARM Ltd, All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/init.h>
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#include <asm/cacheflush.h>
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#include <asm/smp_plat.h>
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#include "common.h"
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extern unsigned long shmobile_smp_fn[];
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extern unsigned long shmobile_smp_arg[];
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extern unsigned long shmobile_smp_mpidr[];
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void shmobile_smp_hook(unsigned int cpu, unsigned long fn, unsigned long arg)
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{
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shmobile_smp_fn[cpu] = 0;
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flush_cache_all();
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shmobile_smp_mpidr[cpu] = cpu_logical_map(cpu);
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shmobile_smp_fn[cpu] = fn;
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shmobile_smp_arg[cpu] = arg;
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flush_cache_all();
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}
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#ifdef CONFIG_HOTPLUG_CPU
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bool shmobile_smp_cpu_can_disable(unsigned int cpu)
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{
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return true; /* Hotplug of any CPU is supported */
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}
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#endif
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