mirror of https://gitee.com/openkylin/linux.git
106 lines
2.5 KiB
C
106 lines
2.5 KiB
C
/*
|
|
* linux/arch/arm/plat-versatile/platsmp.c
|
|
*
|
|
* Copyright (C) 2002 ARM Ltd.
|
|
* All Rights Reserved
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
#include <linux/init.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/device.h>
|
|
#include <linux/jiffies.h>
|
|
#include <linux/smp.h>
|
|
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/hardware/gic.h>
|
|
|
|
/*
|
|
* control for which core is the next to come out of the secondary
|
|
* boot "holding pen"
|
|
*/
|
|
volatile int __cpuinitdata pen_release = -1;
|
|
|
|
/*
|
|
* Write pen_release in a way that is guaranteed to be visible to all
|
|
* observers, irrespective of whether they're taking part in coherency
|
|
* or not. This is necessary for the hotplug code to work reliably.
|
|
*/
|
|
static void __cpuinit write_pen_release(int val)
|
|
{
|
|
pen_release = val;
|
|
smp_wmb();
|
|
__cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
|
|
outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1));
|
|
}
|
|
|
|
static DEFINE_SPINLOCK(boot_lock);
|
|
|
|
void __cpuinit platform_secondary_init(unsigned int cpu)
|
|
{
|
|
/*
|
|
* if any interrupts are already enabled for the primary
|
|
* core (e.g. timer irq), then they will not have been enabled
|
|
* for us: do so
|
|
*/
|
|
gic_secondary_init(0);
|
|
|
|
/*
|
|
* let the primary processor know we're out of the
|
|
* pen, then head off into the C entry point
|
|
*/
|
|
write_pen_release(-1);
|
|
|
|
/*
|
|
* Synchronise with the boot thread.
|
|
*/
|
|
spin_lock(&boot_lock);
|
|
spin_unlock(&boot_lock);
|
|
}
|
|
|
|
int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
|
|
{
|
|
unsigned long timeout;
|
|
|
|
/*
|
|
* Set synchronisation state between this boot processor
|
|
* and the secondary one
|
|
*/
|
|
spin_lock(&boot_lock);
|
|
|
|
/*
|
|
* This is really belt and braces; we hold unintended secondary
|
|
* CPUs in the holding pen until we're ready for them. However,
|
|
* since we haven't sent them a soft interrupt, they shouldn't
|
|
* be there.
|
|
*/
|
|
write_pen_release(cpu_logical_map(cpu));
|
|
|
|
/*
|
|
* Send the secondary CPU a soft interrupt, thereby causing
|
|
* the boot monitor to read the system wide flags register,
|
|
* and branch to the address found there.
|
|
*/
|
|
gic_raise_softirq(cpumask_of(cpu), 1);
|
|
|
|
timeout = jiffies + (1 * HZ);
|
|
while (time_before(jiffies, timeout)) {
|
|
smp_rmb();
|
|
if (pen_release == -1)
|
|
break;
|
|
|
|
udelay(10);
|
|
}
|
|
|
|
/*
|
|
* now the secondary core is starting up let it run its
|
|
* calibrations, then wait for it to finish
|
|
*/
|
|
spin_unlock(&boot_lock);
|
|
|
|
return pen_release != -1 ? -ENOSYS : 0;
|
|
}
|