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smp.c

/*
 * Smp support for ppc.
 *
 * Written by Cort Dougan (cort@cs.nmt.edu) borrowing a great
 * deal of code from the sparc and intel versions.
 *
 * Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/cache.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/residual.h>
#include <asm/time.h>
#include <asm/thread_info.h>
#include <asm/tlbflush.h>
#include <asm/xmon.h>
#include <asm/machdep.h>

volatile int smp_commenced;
int smp_tb_synchronized;
struct cpuinfo_PPC cpu_data[NR_CPUS];
atomic_t ipi_recv;
atomic_t ipi_sent;
cpumask_t cpu_online_map;
cpumask_t cpu_possible_map;
int smp_hw_index[NR_CPUS];
struct thread_info *secondary_ti;
static struct task_struct *idle_tasks[NR_CPUS];

EXPORT_SYMBOL(cpu_online_map);
EXPORT_SYMBOL(cpu_possible_map);

/* SMP operations for this machine */
struct smp_ops_t *smp_ops;

/* all cpu mappings are 1-1 -- Cort */
volatile unsigned long cpu_callin_map[NR_CPUS];

int start_secondary(void *);
void smp_call_function_interrupt(void);
static int __smp_call_function(void (*func) (void *info), void *info,
                         int wait, int target);

/* Low level assembly function used to backup CPU 0 state */
extern void __save_cpu_setup(void);

/* Since OpenPIC has only 4 IPIs, we use slightly different message numbers.
 *
 * Make sure this matches openpic_request_IPIs in open_pic.c, or what shows up
 * in /proc/interrupts will be wrong!!! --Troy */
#define PPC_MSG_CALL_FUNCTION 0
#define PPC_MSG_RESCHEDULE    1
#define PPC_MSG_INVALIDATE_TLB      2
#define PPC_MSG_XMON_BREAK    3

static inline void
smp_message_pass(int target, int msg)
{
      if (smp_ops) {
            atomic_inc(&ipi_sent);
            smp_ops->message_pass(target, msg);
      }
}

/*
 * Common functions
 */
void smp_message_recv(int msg)
{
      atomic_inc(&ipi_recv);

      switch( msg ) {
      case PPC_MSG_CALL_FUNCTION:
            smp_call_function_interrupt();
            break;
      case PPC_MSG_RESCHEDULE:
            set_need_resched();
            break;
      case PPC_MSG_INVALIDATE_TLB:
            _tlbia();
            break;
#ifdef CONFIG_XMON
      case PPC_MSG_XMON_BREAK:
            xmon(get_irq_regs());
            break;
#endif /* CONFIG_XMON */
      default:
            printk("SMP %d: smp_message_recv(): unknown msg %d\n",
                   smp_processor_id(), msg);
            break;
      }
}

/*
 * 750's don't broadcast tlb invalidates so
 * we have to emulate that behavior.
 *   -- Cort
 */
void smp_send_tlb_invalidate(int cpu)
{
      if ( PVR_VER(mfspr(SPRN_PVR)) == 8 )
            smp_message_pass(MSG_ALL_BUT_SELF, PPC_MSG_INVALIDATE_TLB);
}

void smp_send_reschedule(int cpu)
{
      /*
       * This is only used if `cpu' is running an idle task,
       * so it will reschedule itself anyway...
       *
       * This isn't the case anymore since the other CPU could be
       * sleeping and won't reschedule until the next interrupt (such
       * as the timer).
       *  -- Cort
       */
      /* This is only used if `cpu' is running an idle task,
         so it will reschedule itself anyway... */
      smp_message_pass(cpu, PPC_MSG_RESCHEDULE);
}

#ifdef CONFIG_XMON
void smp_send_xmon_break(int cpu)
{
      smp_message_pass(cpu, PPC_MSG_XMON_BREAK);
}
#endif /* CONFIG_XMON */

static void stop_this_cpu(void *dummy)
{
      local_irq_disable();
      while (1)
            ;
}

void smp_send_stop(void)
{
      smp_call_function(stop_this_cpu, NULL, 1, 0);
}

/*
 * Structure and data for smp_call_function(). This is designed to minimise
 * static memory requirements. It also looks cleaner.
 * Stolen from the i386 version.
 */
static DEFINE_SPINLOCK(call_lock);

static struct call_data_struct {
      void (*func) (void *info);
      void *info;
      atomic_t started;
      atomic_t finished;
      int wait;
} *call_data;

/*
 * this function sends a 'generic call function' IPI to all other CPUs
 * in the system.
 */

int smp_call_function(void (*func) (void *info), void *info, int nonatomic,
                  int wait)
/*
 * [SUMMARY] Run a function on all other CPUs.
 * <func> The function to run. This must be fast and non-blocking.
 * <info> An arbitrary pointer to pass to the function.
 * <nonatomic> currently unused.
 * <wait> If true, wait (atomically) until function has completed on other CPUs.
 * [RETURNS] 0 on success, else a negative status code. Does not return until
 * remote CPUs are nearly ready to execute <<func>> or are or have executed.
 *
 * You must not call this function with disabled interrupts or from a
 * hardware interrupt handler or from a bottom half handler.
 */
{
      /* FIXME: get cpu lock with hotplug cpus, or change this to
           bitmask. --RR */
      if (num_online_cpus() <= 1)
            return 0;
      /* Can deadlock when called with interrupts disabled */
      WARN_ON(irqs_disabled());
      return __smp_call_function(func, info, wait, MSG_ALL_BUT_SELF);
}

static int __smp_call_function(void (*func) (void *info), void *info,
                         int wait, int target)
{
      struct call_data_struct data;
      int ret = -1;
      int timeout;
      int ncpus = 1;

      if (target == MSG_ALL_BUT_SELF)
            ncpus = num_online_cpus() - 1;
      else if (target == MSG_ALL)
            ncpus = num_online_cpus();

      data.func = func;
      data.info = info;
      atomic_set(&data.started, 0);
      data.wait = wait;
      if (wait)
            atomic_set(&data.finished, 0);

      spin_lock(&call_lock);
      call_data = &data;
      /* Send a message to all other CPUs and wait for them to respond */
      smp_message_pass(target, PPC_MSG_CALL_FUNCTION);

      /* Wait for response */
      timeout = 1000000;
      while (atomic_read(&data.started) != ncpus) {
            if (--timeout == 0) {
                  printk("smp_call_function on cpu %d: other cpus not responding (%d)\n",
                         smp_processor_id(), atomic_read(&data.started));
                  goto out;
            }
            barrier();
            udelay(1);
      }

      if (wait) {
            timeout = 1000000;
            while (atomic_read(&data.finished) != ncpus) {
                  if (--timeout == 0) {
                        printk("smp_call_function on cpu %d: other cpus not finishing (%d/%d)\n",
                               smp_processor_id(), atomic_read(&data.finished), atomic_read(&data.started));
                        goto out;
                  }
                  barrier();
                  udelay(1);
            }
      }
      ret = 0;

 out:
      spin_unlock(&call_lock);
      return ret;
}

void smp_call_function_interrupt(void)
{
      void (*func) (void *info) = call_data->func;
      void *info = call_data->info;
      int wait = call_data->wait;

      /*
       * Notify initiating CPU that I've grabbed the data and am
       * about to execute the function
       */
      atomic_inc(&call_data->started);
      /*
       * At this point the info structure may be out of scope unless wait==1
       */
      (*func)(info);
      if (wait)
            atomic_inc(&call_data->finished);
}

static void __devinit smp_store_cpu_info(int id)
{
        struct cpuinfo_PPC *c = &cpu_data[id];

      /* assume bogomips are same for everything */
        c->loops_per_jiffy = loops_per_jiffy;
        c->pvr = mfspr(SPRN_PVR);
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
      int num_cpus, i, cpu;
      struct task_struct *p;

      /* Fixup boot cpu */
        smp_store_cpu_info(smp_processor_id());
      cpu_callin_map[smp_processor_id()] = 1;

      if (smp_ops == NULL) {
            printk("SMP not supported on this machine.\n");
            return;
      }

      /* Probe platform for CPUs: always linear. */
      num_cpus = smp_ops->probe();
      
      if (num_cpus < 2)
            smp_tb_synchronized = 1;
      
      for (i = 0; i < num_cpus; ++i)
            cpu_set(i, cpu_possible_map);

      /* Backup CPU 0 state */
      __save_cpu_setup();

      for_each_possible_cpu(cpu) {
            if (cpu == smp_processor_id())
                  continue;
            /* create a process for the processor */
            p = fork_idle(cpu);
            if (IS_ERR(p))
                  panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
            task_thread_info(p)->cpu = cpu;
            idle_tasks[cpu] = p;
      }
}

void __devinit smp_prepare_boot_cpu(void)
{
      cpu_set(smp_processor_id(), cpu_online_map);
      cpu_set(smp_processor_id(), cpu_possible_map);
}

int __init setup_profiling_timer(unsigned int multiplier)
{
      return 0;
}

/* Processor coming up starts here */
int __devinit start_secondary(void *unused)
{
      int cpu;

      atomic_inc(&init_mm.mm_count);
      current->active_mm = &init_mm;

      cpu = smp_processor_id();
        smp_store_cpu_info(cpu);
      set_dec(tb_ticks_per_jiffy);
      preempt_disable();
      cpu_callin_map[cpu] = 1;

      printk("CPU %d done callin...\n", cpu);
      smp_ops->setup_cpu(cpu);
      printk("CPU %d done setup...\n", cpu);
      smp_ops->take_timebase();
      printk("CPU %d done timebase take...\n", cpu);

      spin_lock(&call_lock);
      cpu_set(cpu, cpu_online_map);
      spin_unlock(&call_lock);

      local_irq_enable();

      cpu_idle();
      return 0;
}

int __cpu_up(unsigned int cpu)
{
      char buf[32];
      int c;

      secondary_ti = task_thread_info(idle_tasks[cpu]);
      mb();

      /*
       * There was a cache flush loop here to flush the cache
       * to memory for the first 8MB of RAM.  The cache flush
       * has been pushed into the kick_cpu function for those
       * platforms that need it.
       */

      /* wake up cpu */
      smp_ops->kick_cpu(cpu);
      
      /*
       * wait to see if the cpu made a callin (is actually up).
       * use this value that I found through experimentation.
       * -- Cort
       */
      for (c = 1000; c && !cpu_callin_map[cpu]; c--)
            udelay(100);

      if (!cpu_callin_map[cpu]) {
            sprintf(buf, "didn't find cpu %u", cpu);
            if (ppc_md.progress) ppc_md.progress(buf, 0x360+cpu);
            printk("Processor %u is stuck.\n", cpu);
            return -ENOENT;
      }

      sprintf(buf, "found cpu %u", cpu);
      if (ppc_md.progress) ppc_md.progress(buf, 0x350+cpu);
      printk("Processor %d found.\n", cpu);

      smp_ops->give_timebase();

      /* Wait until cpu puts itself in the online map */
      while (!cpu_online(cpu))
            cpu_relax();

      return 0;
}

void smp_cpus_done(unsigned int max_cpus)
{
      smp_ops->setup_cpu(0);
}

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