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>
66 lines
1.8 KiB
C
66 lines
1.8 KiB
C
/*
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* SMP support for r8a7791
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*
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* Copyright (C) 2013 Renesas Solutions Corp.
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* Copyright (C) 2013 Magnus Damm
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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 as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/io.h>
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#include <asm/smp_plat.h>
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#include "common.h"
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#include "platsmp-apmu.h"
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#include "r8a7791.h"
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#include "rcar-gen2.h"
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static struct rcar_apmu_config r8a7791_apmu_config[] = {
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{
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.iomem = DEFINE_RES_MEM(0xe6152000, 0x188),
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.cpus = { 0, 1 },
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}
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};
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static void __init r8a7791_smp_prepare_cpus(unsigned int max_cpus)
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{
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/* let APMU code install data related to shmobile_boot_vector */
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shmobile_smp_apmu_prepare_cpus(max_cpus,
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r8a7791_apmu_config,
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ARRAY_SIZE(r8a7791_apmu_config));
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rcar_gen2_pm_init();
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}
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static int r8a7791_smp_boot_secondary(unsigned int cpu,
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struct task_struct *idle)
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{
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/* Error out when hardware debug mode is enabled */
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if (rcar_gen2_read_mode_pins() & BIT(21)) {
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pr_warn("Unable to boot CPU%u when MD21 is set\n", cpu);
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return -ENOTSUPP;
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}
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return shmobile_smp_apmu_boot_secondary(cpu, idle);
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}
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struct smp_operations r8a7791_smp_ops __initdata = {
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.smp_prepare_cpus = r8a7791_smp_prepare_cpus,
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.smp_boot_secondary = r8a7791_smp_boot_secondary,
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#ifdef CONFIG_HOTPLUG_CPU
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.cpu_can_disable = shmobile_smp_cpu_can_disable,
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.cpu_die = shmobile_smp_apmu_cpu_die,
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.cpu_kill = shmobile_smp_apmu_cpu_kill,
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#endif
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};
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