7fa22bd546
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>
83 lines
2.1 KiB
C
83 lines
2.1 KiB
C
/*
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* linux/arch/arm/mach-realview/platsmp.c
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*
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* Copyright (C) 2002 ARM Ltd.
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* 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/smp.h>
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#include <linux/io.h>
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#include <mach/hardware.h>
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#include <asm/hardware/gic.h>
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#include <asm/mach-types.h>
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#include <asm/smp_scu.h>
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#include <asm/unified.h>
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#include <mach/board-eb.h>
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#include <mach/board-pb11mp.h>
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#include <mach/board-pbx.h>
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#include "core.h"
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extern void versatile_secondary_startup(void);
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static void __iomem *scu_base_addr(void)
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{
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if (machine_is_realview_eb_mp())
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return __io_address(REALVIEW_EB11MP_SCU_BASE);
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else if (machine_is_realview_pb11mp())
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return __io_address(REALVIEW_TC11MP_SCU_BASE);
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else if (machine_is_realview_pbx() &&
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(core_tile_pbx11mp() || core_tile_pbxa9mp()))
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return __io_address(REALVIEW_PBX_TILE_SCU_BASE);
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else
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return (void __iomem *)0;
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}
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/*
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* Initialise the CPU possible map early - this describes the CPUs
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* which may be present or become present in the system.
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*/
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void __init smp_init_cpus(void)
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{
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void __iomem *scu_base = scu_base_addr();
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unsigned int i, ncores;
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ncores = scu_base ? scu_get_core_count(scu_base) : 1;
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/* sanity check */
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if (ncores > NR_CPUS) {
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printk(KERN_WARNING
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"Realview: no. of cores (%d) greater than configured "
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"maximum of %d - clipping\n",
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ncores, NR_CPUS);
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ncores = NR_CPUS;
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}
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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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scu_enable(scu_base_addr());
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/*
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* Write the address of secondary startup into the
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* system-wide flags register. The BootMonitor waits
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* until it receives a soft interrupt, and then the
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* secondary CPU branches to this address.
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*/
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__raw_writel(BSYM(virt_to_phys(versatile_secondary_startup)),
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__io_address(REALVIEW_SYS_FLAGSSET));
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}
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