linux/arch/arm/mach-ux500/platsmp.c

/*
 * Copyright (C) 2002 ARM Ltd.
 * Copyright (C) 2008 STMicroelctronics.
 * Copyright (C) 2009 ST-Ericsson.
 * Author: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
 *
 * This file is based on arm realview platform
 *
 * 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/smp.h>
#include <linux/io.h>

#include <asm/cacheflush.h>
#include <asm/smp_scu.h>
#include <mach/hardware.h>

/*
 * control for which core is the next to come out of the secondary
 * boot "holding pen"
 */
volatile int 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 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);

	/*
	 * 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.
	 */
	write_pen_release(cpu);

	smp_cross_call(cpumask_of(cpu), 1);

	timeout = jiffies + (1 * HZ);
	while (time_before(jiffies, timeout)) {
		if (pen_release == -1)
			break;
	}

	/*
	 * 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 wakeup_secondary(void)
{
	/*
	 * write the address of secondary startup into the backup ram register
	 * at offset 0x1FF4, then write the magic number 0xA1FEED01 to the
	 * backup ram register at offset 0x1FF0, which is what boot rom code
	 * is waiting for. This would wake up the secondary core from WFE
	 */
#define U8500_CPU1_JUMPADDR_OFFSET 0x1FF4
	__raw_writel(virt_to_phys(u8500_secondary_startup),
		__io_address(UX500_BACKUPRAM0_BASE) +
		U8500_CPU1_JUMPADDR_OFFSET);

#define U8500_CPU1_WAKEMAGIC_OFFSET 0x1FF0
	__raw_writel(0xA1FEED01,
		__io_address(UX500_BACKUPRAM0_BASE) +
		U8500_CPU1_WAKEMAGIC_OFFSET);

	/* make sure write buffer is drained */
	mb();
}

/*
 * 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;

	ncores = scu_get_core_count(__io_address(UX500_SCU_BASE));

	/* sanity check */
	if (ncores > NR_CPUS) {
		printk(KERN_WARNING
		       "U8500: no. of cores (%d) greater than configured "
		       "maximum of %d - clipping\n",
		       ncores, NR_CPUS);
		ncores = NR_CPUS;
	}

	for (i = 0; i < ncores; i++)
		set_cpu_possible(i, true);
}

void __init platform_smp_prepare_cpus(unsigned int max_cpus)
{
	int i;

	/*
	 * Initialise the present map, which describes the set of CPUs
	 * actually populated at the present time.
	 */
	for (i = 0; i < max_cpus; i++)
		set_cpu_present(i, true);

	scu_enable(__io_address(UX500_SCU_BASE));
	wakeup_secondary();
}