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smp.c

/*
 * SMP support for pSeries machines.
 *
 * Dave Engebretsen, Peter Bergner, and
 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
 *
 * Plus various changes from other IBM teams...
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */


#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/cache.h>
#include <linux/err.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>

#include <asm/ptrace.h>
#include <asm/atomic.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/paca.h>
#include <asm/time.h>
#include <asm/machdep.h>
#include <asm/cputable.h>
#include <asm/firmware.h>
#include <asm/system.h>
#include <asm/rtas.h>
#include <asm/pSeries_reconfig.h>
#include <asm/mpic.h>
#include <asm/vdso_datapage.h>
#include <asm/cputhreads.h>

#include "plpar_wrappers.h"
#include "pseries.h"
#include "xics.h"


/*
 * The Primary thread of each non-boot processor was started from the OF client
 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
 */
static cpumask_t of_spin_map;

extern void generic_secondary_smp_init(unsigned long);

/**
 * smp_startup_cpu() - start the given cpu
 *
 * At boot time, there is nothing to do for primary threads which were
 * started from Open Firmware.  For anything else, call RTAS with the
 * appropriate start location.
 *
 * Returns:
 *    0     - failure
 *    1     - success
 */
static inline int __devinit smp_startup_cpu(unsigned int lcpu)
{
      int status;
      unsigned long start_here = __pa((u32)*((unsigned long *)
                                     generic_secondary_smp_init));
      unsigned int pcpu;
      int start_cpu;

      if (cpu_isset(lcpu, of_spin_map))
            /* Already started by OF and sitting in spin loop */
            return 1;

      pcpu = get_hard_smp_processor_id(lcpu);

      /* Fixup atomic count: it exited inside IRQ handler. */
      task_thread_info(paca[lcpu].__current)->preempt_count = 0;

      /* 
       * If the RTAS start-cpu token does not exist then presume the
       * cpu is already spinning.
       */
      start_cpu = rtas_token("start-cpu");
      if (start_cpu == RTAS_UNKNOWN_SERVICE)
            return 1;

      status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
      if (status != 0) {
            printk(KERN_ERR "start-cpu failed: %i\n", status);
            return 0;
      }

      return 1;
}

#ifdef CONFIG_XICS
static void __devinit smp_xics_setup_cpu(int cpu)
{
      if (cpu != boot_cpuid)
            xics_setup_cpu();

      if (firmware_has_feature(FW_FEATURE_SPLPAR))
            vpa_init(cpu);

      cpu_clear(cpu, of_spin_map);

}
#endif /* CONFIG_XICS */

static DEFINE_SPINLOCK(timebase_lock);
static unsigned long timebase = 0;

static void __devinit pSeries_give_timebase(void)
{
      spin_lock(&timebase_lock);
      rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
      timebase = get_tb();
      spin_unlock(&timebase_lock);

      while (timebase)
            barrier();
      rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
}

static void __devinit pSeries_take_timebase(void)
{
      while (!timebase)
            barrier();
      spin_lock(&timebase_lock);
      set_tb(timebase >> 32, timebase & 0xffffffff);
      timebase = 0;
      spin_unlock(&timebase_lock);
}

static void __devinit smp_pSeries_kick_cpu(int nr)
{
      BUG_ON(nr < 0 || nr >= NR_CPUS);

      if (!smp_startup_cpu(nr))
            return;

      /*
       * The processor is currently spinning, waiting for the
       * cpu_start field to become non-zero After we set cpu_start,
       * the processor will continue on to secondary_start
       */
      paca[nr].cpu_start = 1;
}

static int smp_pSeries_cpu_bootable(unsigned int nr)
{
      /* Special case - we inhibit secondary thread startup
       * during boot if the user requests it.
       */
      if (system_state < SYSTEM_RUNNING &&
          cpu_has_feature(CPU_FTR_SMT) &&
          !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
            return 0;

      return 1;
}
#ifdef CONFIG_MPIC
static struct smp_ops_t pSeries_mpic_smp_ops = {
      .message_pass     = smp_mpic_message_pass,
      .probe            = smp_mpic_probe,
      .kick_cpu   = smp_pSeries_kick_cpu,
      .setup_cpu  = smp_mpic_setup_cpu,
};
#endif
#ifdef CONFIG_XICS
static struct smp_ops_t pSeries_xics_smp_ops = {
      .message_pass     = smp_xics_message_pass,
      .probe            = smp_xics_probe,
      .kick_cpu   = smp_pSeries_kick_cpu,
      .setup_cpu  = smp_xics_setup_cpu,
      .cpu_bootable     = smp_pSeries_cpu_bootable,
};
#endif

/* This is called very early */
static void __init smp_init_pseries(void)
{
      int i;

      pr_debug(" -> smp_init_pSeries()\n");

      /* Mark threads which are still spinning in hold loops. */
      if (cpu_has_feature(CPU_FTR_SMT)) {
            for_each_present_cpu(i) { 
                  if (cpu_thread_in_core(i) == 0)
                        cpu_set(i, of_spin_map);
            }
      } else {
            of_spin_map = cpu_present_map;
      }

      cpu_clear(boot_cpuid, of_spin_map);

      /* Non-lpar has additional take/give timebase */
      if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
            smp_ops->give_timebase = pSeries_give_timebase;
            smp_ops->take_timebase = pSeries_take_timebase;
      }

      pr_debug(" <- smp_init_pSeries()\n");
}

#ifdef CONFIG_MPIC
void __init smp_init_pseries_mpic(void)
{
      smp_ops = &pSeries_mpic_smp_ops;

      smp_init_pseries();
}
#endif

void __init smp_init_pseries_xics(void)
{
      smp_ops = &pSeries_xics_smp_ops;

      smp_init_pseries();
}

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