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If an ARM system has multiple cpus in the same socket and the kernel is booted with maxcpus=1, secondary cpus are possible but not present due to how platform_smp_prepare_cpus() is called. Since most typical ARM processors don't actually support physical hotplug, initialize the present map to be equal to the possible map in generic ARM SMP code. Also, always call platform_smp_prepare_cpus() as long as max_cpus is non-zero (0 means no SMP) to allow platform code to do any SMP setup. After applying this patch it's possible to boot an ARM system with maxcpus=1 on the command line and then hotplug in secondary cpus via sysfs. This is more in line with how x86 does things. Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Kukjin Kim <kgene.kim@samsung.com> Cc: David Brown <davidb@codeaurora.org> Cc: Tony Lindgren <tony@atomide.com> Cc: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com> Cc: Linus Walleij <linus.walleij@stericsson.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
68 lines
1.5 KiB
C
68 lines
1.5 KiB
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 <linux/errno.h>
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#include <linux/delay.h>
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#include <linux/device.h>
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#include <linux/smp.h>
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#include <linux/io.h>
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#include <asm/hardware/gic.h>
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#include <asm/localtimer.h>
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#include <asm/mach-types.h>
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#include <mach/common.h>
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static unsigned int __init shmobile_smp_get_core_count(void)
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{
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if (machine_is_ag5evm())
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return sh73a0_get_core_count();
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return 1;
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}
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static void __init shmobile_smp_prepare_cpus(void)
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{
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if (machine_is_ag5evm())
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sh73a0_smp_prepare_cpus();
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}
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void __cpuinit platform_secondary_init(unsigned int cpu)
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{
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trace_hardirqs_off();
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if (machine_is_ag5evm())
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sh73a0_secondary_init(cpu);
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}
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int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
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{
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if (machine_is_ag5evm())
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return sh73a0_boot_secondary(cpu);
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return -ENOSYS;
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}
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void __init smp_init_cpus(void)
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{
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unsigned int ncores = shmobile_smp_get_core_count();
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unsigned int i;
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for (i = 0; i < ncores; i++)
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set_cpu_possible(i, true);
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set_smp_cross_call(gic_raise_softirq);
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}
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void __init platform_smp_prepare_cpus(unsigned int max_cpus)
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{
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shmobile_smp_prepare_cpus();
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}
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