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smp.c

/*
** SMP Support
**
** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
** Copyright (C) 2001,2004 Grant Grundler <grundler@parisc-linux.org>
** 
** Lots of stuff stolen from arch/alpha/kernel/smp.c
** ...and then parisc stole from arch/ia64/kernel/smp.c. Thanks David! :^)
**
** Thanks to John Curry and Ullas Ponnadi. I learned a lot from their work.
** -grant (1/12/2001)
**
**    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/types.h>
#include <linux/spinlock.h>
#include <linux/slab.h>

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/bitops.h>

#include <asm/system.h>
#include <asm/atomic.h>
#include <asm/current.h>
#include <asm/delay.h>
#include <asm/tlbflush.h>

#include <asm/io.h>
#include <asm/irq.h>          /* for CPU_IRQ_REGION and friends */
#include <asm/mmu_context.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/unistd.h>
#include <asm/cacheflush.h>

#undef DEBUG_SMP
#ifdef DEBUG_SMP
static int smp_debug_lvl = 0;
#define smp_debug(lvl, printargs...)            \
            if (lvl >= smp_debug_lvl)     \
                  printk(printargs);
#else
#define smp_debug(lvl, ...)
#endif /* DEBUG_SMP */

DEFINE_SPINLOCK(smp_lock);

volatile struct task_struct *smp_init_current_idle_task;

static volatile int cpu_now_booting __read_mostly = 0;      /* track which CPU is booting */

static int parisc_max_cpus __read_mostly = 1;

/* online cpus are ones that we've managed to bring up completely
 * possible cpus are all valid cpu 
 * present cpus are all detected cpu
 *
 * On startup we bring up the "possible" cpus. Since we discover
 * CPUs later, we add them as hotplug, so the possible cpu mask is
 * empty in the beginning.
 */

cpumask_t cpu_online_map   __read_mostly = CPU_MASK_NONE;   /* Bitmap of online CPUs */
cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;    /* Bitmap of Present CPUs */

EXPORT_SYMBOL(cpu_online_map);
EXPORT_SYMBOL(cpu_possible_map);

DEFINE_PER_CPU(spinlock_t, ipi_lock) = SPIN_LOCK_UNLOCKED;

enum ipi_message_type {
      IPI_NOP=0,
      IPI_RESCHEDULE=1,
      IPI_CALL_FUNC,
      IPI_CALL_FUNC_SINGLE,
      IPI_CPU_START,
      IPI_CPU_STOP,
      IPI_CPU_TEST
};


/********** SMP inter processor interrupt and communication routines */

#undef PER_CPU_IRQ_REGION
#ifdef PER_CPU_IRQ_REGION
/* XXX REVISIT Ignore for now.
**    *May* need this "hook" to register IPI handler
**    once we have perCPU ExtIntr switch tables.
*/
static void
ipi_init(int cpuid)
{
#error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region

      if(cpu_online(cpuid) )
      {
            switch_to_idle_task(current);
      }

      return;
}
#endif


/*
** Yoink this CPU from the runnable list... 
**
*/
static void
halt_processor(void) 
{
      /* REVISIT : redirect I/O Interrupts to another CPU? */
      /* REVISIT : does PM *know* this CPU isn't available? */
      cpu_clear(smp_processor_id(), cpu_online_map);
      local_irq_disable();
      for (;;)
            ;
}


irqreturn_t
ipi_interrupt(int irq, void *dev_id) 
{
      int this_cpu = smp_processor_id();
      struct cpuinfo_parisc *p = &cpu_data[this_cpu];
      unsigned long ops;
      unsigned long flags;

      /* Count this now; we may make a call that never returns. */
      p->ipi_count++;

      mb(); /* Order interrupt and bit testing. */

      for (;;) {
            spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
            spin_lock_irqsave(lock, flags);
            ops = p->pending_ipi;
            p->pending_ipi = 0;
            spin_unlock_irqrestore(lock, flags);

            mb(); /* Order bit clearing and data access. */

            if (!ops)
                break;

            while (ops) {
                  unsigned long which = ffz(~ops);

                  ops &= ~(1 << which);

                  switch (which) {
                  case IPI_NOP:
                        smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
                        break;
                        
                  case IPI_RESCHEDULE:
                        smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
                        /*
                         * Reschedule callback.  Everything to be
                         * done is done by the interrupt return path.
                         */
                        break;

                  case IPI_CALL_FUNC:
                        smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
                        generic_smp_call_function_interrupt();
                        break;

                  case IPI_CALL_FUNC_SINGLE:
                        smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC_SINGLE\n", this_cpu);
                        generic_smp_call_function_single_interrupt();
                        break;

                  case IPI_CPU_START:
                        smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
                        break;

                  case IPI_CPU_STOP:
                        smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
                        halt_processor();
                        break;

                  case IPI_CPU_TEST:
                        smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
                        break;

                  default:
                        printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
                              this_cpu, which);
                        return IRQ_NONE;
                  } /* Switch */
            /* let in any pending interrupts */
            local_irq_enable();
            local_irq_disable();
            } /* while (ops) */
      }
      return IRQ_HANDLED;
}


static inline void
ipi_send(int cpu, enum ipi_message_type op)
{
      struct cpuinfo_parisc *p = &cpu_data[cpu];
      spinlock_t *lock = &per_cpu(ipi_lock, cpu);
      unsigned long flags;

      spin_lock_irqsave(lock, flags);
      p->pending_ipi |= 1 << op;
      gsc_writel(IPI_IRQ - CPU_IRQ_BASE, cpu_data[cpu].hpa);
      spin_unlock_irqrestore(lock, flags);
}

static void
send_IPI_mask(cpumask_t mask, enum ipi_message_type op)
{
      int cpu;

      for_each_cpu_mask(cpu, mask)
            ipi_send(cpu, op);
}

static inline void
send_IPI_single(int dest_cpu, enum ipi_message_type op)
{
      if (dest_cpu == NO_PROC_ID) {
            BUG();
            return;
      }

      ipi_send(dest_cpu, op);
}

static inline void
send_IPI_allbutself(enum ipi_message_type op)
{
      int i;
      
      for_each_online_cpu(i) {
            if (i != smp_processor_id())
                  send_IPI_single(i, op);
      }
}


inline void 
smp_send_stop(void)     { send_IPI_allbutself(IPI_CPU_STOP); }

static inline void
smp_send_start(void)    { send_IPI_allbutself(IPI_CPU_START); }

void 
smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }

void
smp_send_all_nop(void)
{
      send_IPI_allbutself(IPI_NOP);
}

void arch_send_call_function_ipi(cpumask_t mask)
{
      send_IPI_mask(mask, IPI_CALL_FUNC);
}

void arch_send_call_function_single_ipi(int cpu)
{
      send_IPI_single(cpu, IPI_CALL_FUNC_SINGLE);
}

/*
 * Flush all other CPU's tlb and then mine.  Do this with on_each_cpu()
 * as we want to ensure all TLB's flushed before proceeding.
 */

void
smp_flush_tlb_all(void)
{
      on_each_cpu(flush_tlb_all_local, NULL, 1);
}

/*
 * Called by secondaries to update state and initialize CPU registers.
 */
static void __init
smp_cpu_init(int cpunum)
{
      extern int init_per_cpu(int);  /* arch/parisc/kernel/processor.c */
      extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */
      extern void start_cpu_itimer(void); /* arch/parisc/kernel/time.c */

      /* Set modes and Enable floating point coprocessor */
      (void) init_per_cpu(cpunum);

      disable_sr_hashing();

      mb();

      /* Well, support 2.4 linux scheme as well. */
      if (cpu_test_and_set(cpunum, cpu_online_map))
      {
            extern void machine_halt(void); /* arch/parisc.../process.c */

            printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
            machine_halt();
      }  

      /* Initialise the idle task for this CPU */
      atomic_inc(&init_mm.mm_count);
      current->active_mm = &init_mm;
      if(current->mm)
            BUG();
      enter_lazy_tlb(&init_mm, current);

      init_IRQ();   /* make sure no IRQs are enabled or pending */
      start_cpu_itimer();
}


/*
 * Slaves start using C here. Indirectly called from smp_slave_stext.
 * Do what start_kernel() and main() do for boot strap processor (aka monarch)
 */
void __init smp_callin(void)
{
      int slave_id = cpu_now_booting;

      smp_cpu_init(slave_id);
      preempt_disable();

      flush_cache_all_local(); /* start with known state */
      flush_tlb_all_local(NULL);

      local_irq_enable();  /* Interrupts have been off until now */

      cpu_idle();      /* Wait for timer to schedule some work */

      /* NOTREACHED */
      panic("smp_callin() AAAAaaaaahhhh....\n");
}

/*
 * Bring one cpu online.
 */
int __cpuinit smp_boot_one_cpu(int cpuid)
{
      struct task_struct *idle;
      long timeout;

      /* 
       * Create an idle task for this CPU.  Note the address wed* give 
       * to kernel_thread is irrelevant -- it's going to start
       * where OS_BOOT_RENDEVZ vector in SAL says to start.  But
       * this gets all the other task-y sort of data structures set
       * up like we wish.   We need to pull the just created idle task 
       * off the run queue and stuff it into the init_tasks[] array.  
       * Sheesh . . .
       */

      idle = fork_idle(cpuid);
      if (IS_ERR(idle))
            panic("SMP: fork failed for CPU:%d", cpuid);

      task_thread_info(idle)->cpu = cpuid;

      /* Let _start know what logical CPU we're booting
      ** (offset into init_tasks[],cpu_data[])
      */
      cpu_now_booting = cpuid;

      /* 
      ** boot strap code needs to know the task address since
      ** it also contains the process stack.
      */
      smp_init_current_idle_task = idle ;
      mb();

      printk("Releasing cpu %d now, hpa=%lx\n", cpuid, cpu_data[cpuid].hpa);

      /*
      ** This gets PDC to release the CPU from a very tight loop.
      **
      ** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
      ** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which 
      ** is executed after receiving the rendezvous signal (an interrupt to 
      ** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the 
      ** contents of memory are valid."
      */
      gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, cpu_data[cpuid].hpa);
      mb();

      /* 
       * OK, wait a bit for that CPU to finish staggering about. 
       * Slave will set a bit when it reaches smp_cpu_init().
       * Once the "monarch CPU" sees the bit change, it can move on.
       */
      for (timeout = 0; timeout < 10000; timeout++) {
            if(cpu_online(cpuid)) {
                  /* Which implies Slave has started up */
                  cpu_now_booting = 0;
                  smp_init_current_idle_task = NULL;
                  goto alive ;
            }
            udelay(100);
            barrier();
      }

      put_task_struct(idle);
      idle = NULL;

      printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
      return -1;

alive:
      /* Remember the Slave data */
      smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
            cpuid, timeout * 100);
      return 0;
}

void __devinit smp_prepare_boot_cpu(void)
{
      int bootstrap_processor=cpu_data[0].cpuid;      /* CPU ID of BSP */

      /* Setup BSP mappings */
      printk("SMP: bootstrap CPU ID is %d\n",bootstrap_processor);

      cpu_set(bootstrap_processor, cpu_online_map);
      cpu_set(bootstrap_processor, cpu_present_map);
}



/*
** inventory.c:do_inventory() hasn't yet been run and thus we
** don't 'discover' the additional CPUs until later.
*/
void __init smp_prepare_cpus(unsigned int max_cpus)
{
      cpus_clear(cpu_present_map);
      cpu_set(0, cpu_present_map);

      parisc_max_cpus = max_cpus;
      if (!max_cpus)
            printk(KERN_INFO "SMP mode deactivated.\n");
}


void smp_cpus_done(unsigned int cpu_max)
{
      return;
}


int __cpuinit __cpu_up(unsigned int cpu)
{
      if (cpu != 0 && cpu < parisc_max_cpus)
            smp_boot_one_cpu(cpu);

      return cpu_online(cpu) ? 0 : -ENOSYS;
}

#ifdef CONFIG_PROC_FS
int __init
setup_profiling_timer(unsigned int multiplier)
{
      return -EINVAL;
}
#endif

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