linux/arch/arm/mach-integrator/platsmp.c
Russell King 7ac5ae4b12 [ARM SMP] Ensure secondary CPUs see their pen release
Since the secondary CPUs will not be operating in symetric mode
while they are held in the pen, we need to ensure that the write
to pen_release is visible to them, by flushing the cache.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-07-29 16:36:48 +01:00

197 lines
4.8 KiB
C

/*
* linux/arch/arm/mach-cintegrator/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/kernel.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/delay.h>
#include <asm/mmu_context.h>
#include <asm/procinfo.h>
#include <asm/ptrace.h>
#include <asm/smp.h>
extern void integrator_secondary_startup(void);
/*
* control for which core is the next to come out of the secondary
* boot "holding pen"
*/
volatile int __cpuinitdata pen_release = -1;
unsigned long __cpuinitdata phys_pen_release = 0;
static DEFINE_SPINLOCK(boot_lock);
void __cpuinit platform_secondary_init(unsigned int cpu)
{
/*
* the primary core may have used a "cross call" soft interrupt
* to get this processor out of WFI in the BootMonitor - make
* sure that we are no longer being sent this soft interrupt
*/
smp_cross_call_done(cpumask_of_cpu(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
*/
secondary_scan_irqs();
/*
* let the primary processor know we're out of the
* pen, then head off into the C entry point
*/
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);
/*
* 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();
/*
* XXX
*
* This is a later addition to the booting protocol: the
* bootMonitor now puts secondary cores into WFI, so
* poke_milo() no longer gets the cores moving; we need
* to send a soft interrupt to wake the secondary core.
* Use smp_cross_call() for this, since there's little
* point duplicating the code here
*/
smp_cross_call(cpumask_of_cpu(cpu));
timeout = jiffies + (1 * HZ);
while (time_before(jiffies, timeout)) {
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;
}
static void __init poke_milo(void)
{
extern void secondary_startup(void);
/* nobody is to be released from the pen yet */
pen_release = -1;
phys_pen_release = virt_to_phys(&pen_release);
/*
* write the address of secondary startup into the system-wide
* flags register, then clear the bottom two bits, which is what
* BootMonitor is waiting for
*/
#if 1
#define CINTEGRATOR_HDR_FLAGSS_OFFSET 0x30
__raw_writel(virt_to_phys(integrator_secondary_startup),
(IO_ADDRESS(INTEGRATOR_HDR_BASE) +
CINTEGRATOR_HDR_FLAGSS_OFFSET));
#define CINTEGRATOR_HDR_FLAGSC_OFFSET 0x34
__raw_writel(3,
(IO_ADDRESS(INTEGRATOR_HDR_BASE) +
CINTEGRATOR_HDR_FLAGSC_OFFSET));
#endif
mb();
}
void __init smp_prepare_cpus(unsigned int max_cpus)
{
unsigned int ncores = get_core_count();
unsigned int cpu = smp_processor_id();
int i;
/* sanity check */
if (ncores == 0) {
printk(KERN_ERR
"Integrator/CP: strange CM count of 0? Default to 1\n");
ncores = 1;
}
if (ncores > NR_CPUS) {
printk(KERN_WARNING
"Integrator/CP: no. of cores (%d) greater than configured "
"maximum of %d - clipping\n",
ncores, NR_CPUS);
ncores = NR_CPUS;
}
/*
* start with some more config for the Boot CPU, now that
* the world is a bit more alive (which was not the case
* when smp_prepare_boot_cpu() was called)
*/
smp_store_cpu_info(cpu);
/*
* are we trying to boot more cores than exist?
*/
if (max_cpus > ncores)
max_cpus = ncores;
/*
* Initialise the possible/present maps.
* cpu_possible_map describes the set of CPUs which may be present
* cpu_present_map describes the set of CPUs populated
*/
for (i = 0; i < max_cpus; i++) {
cpu_set(i, cpu_possible_map);
cpu_set(i, cpu_present_map);
}
/*
* Do we need any more CPUs? If so, then let them know where
* to start. Note that, on modern versions of MILO, the "poke"
* doesn't actually do anything until each individual core is
* sent a soft interrupt to get it out of WFI
*/
if (max_cpus > 1)
poke_milo();
}