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platsmp.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();
}

/*
 * 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 = get_core_count();

      for (i = 0; i < ncores; i++)
            cpu_set(i, cpu_possible_map);
}

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

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