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/*
* arch/arm/mach-spear13xx/platsmp.c
*
* based upon linux/arch/arm/mach-realview/platsmp.c
*
* Copyright (C) 2012 ST Microelectronics Ltd.
* Shiraz Hashim <shiraz.hashim@st.com>
*
* 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/delay.h>
#include <linux/jiffies.h>
#include <linux/io.h>
#include <linux/smp.h>
#include <asm/cacheflush.h>
#include <asm/hardware/gic.h>
#include <asm/smp_scu.h>
#include <mach/spear.h>
/*
* control for which core is the next to come out of the secondary
* boot "holding pen"
*/
volatile int __cpuinitdata pen_release = -1;
static DEFINE_SPINLOCK(boot_lock);
static void __iomem *scu_base = IOMEM(VA_SCU_BASE);
extern void spear13xx_secondary_startup(void);
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
*/
pen_release = -1;
smp_wmb();
/*
* 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);
/*
* The secondary processor is waiting to be released from
* the holding pen - release it, then wait for it to flag
* that it has been released by resetting pen_release.
*
* Note that "pen_release" is the hardware CPU ID, whereas
* "cpu" is Linux's internal ID.
*/
pen_release = cpu;
flush_cache_all();
outer_flush_all();
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;
}
/*
* Initialise the CPU possible map early - this describes the CPUs
* which may be present or become present in the system.
*/
void __init smp_init_cpus(void)
{
unsigned int i, ncores = scu_get_core_count(scu_base);
if (ncores > nr_cpu_ids) {
pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
ncores, nr_cpu_ids);
ncores = nr_cpu_ids;
}
for (i = 0; i < ncores; i++)
set_cpu_possible(i, true);
set_smp_cross_call(gic_raise_softirq);
}
void __init platform_smp_prepare_cpus(unsigned int max_cpus)
{
scu_enable(scu_base);
/*
* Write the address of secondary startup into the system-wide location
* (presently it is in SRAM). The BootMonitor waits until it receives a
* soft interrupt, and then the secondary CPU branches to this address.
*/
__raw_writel(virt_to_phys(spear13xx_secondary_startup), SYS_LOCATION);
}
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