arch/sh/kernel/smp.c

   1 /*
   2  * arch/sh/kernel/smp.c
   3  *
   4  * SMP support for the SuperH processors.
   5  *
   6  * Copyright (C) 2002, 2003 Paul Mundt
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License as published by the
  10  * Free Software Foundation; either version 2 of the License, or (at your
  11  * option) any later version.
  12  */
  13
  14 #include <linux/err.h>
  15 #include <linux/cache.h>
  16 #include <linux/cpumask.h>
  17 #include <linux/delay.h>
  18 #include <linux/init.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/threads.h>
  22 #include <linux/module.h>
  23 #include <linux/time.h>
  24 #include <linux/timex.h>
  25 #include <linux/sched.h>
  26 #include <linux/module.h>
  27
  28 #include <asm/atomic.h>
  29 #include <asm/processor.h>
  30 #include <asm/system.h>
  31 #include <asm/mmu_context.h>
  32 #include <asm/smp.h>
  33
  34 /*
  35  * This was written with the Sega Saturn (SMP SH-2 7604) in mind,
  36  * but is designed to be usable regardless if there's an MMU
  37  * present or not.
  38  */
  39 struct sh_cpuinfo cpu_data[NR_CPUS];
  40
  41 extern void per_cpu_trap_init(void);
  42
  43 cpumask_t cpu_possible_map;
  44 EXPORT_SYMBOL(cpu_possible_map);
  45
  46 cpumask_t cpu_online_map;
  47 EXPORT_SYMBOL(cpu_online_map);
  48 static atomic_t cpus_booted = ATOMIC_INIT(0);
  49
  50 /* These are defined by the board-specific code. */
  51
  52 /*
  53  * Cause the function described by call_data to be executed on the passed
  54  * cpu.  When the function has finished, increment the finished field of
  55  * call_data.
  56  */
  57 void __smp_send_ipi(unsigned int cpu, unsigned int action);
  58
  59 /*
  60  * Find the number of available processors
  61  */
  62 unsigned int __smp_probe_cpus(void);
  63
  64 /*
  65  * Start a particular processor
  66  */
  67 void __smp_slave_init(unsigned int cpu);
  68
  69 /*
  70  * Run specified function on a particular processor.
  71  */
  72 void __smp_call_function(unsigned int cpu);
  73
  74 static inline void __init smp_store_cpu_info(unsigned int cpu)
  75 {
  76         cpu_data[cpu].loops_per_jiffy = loops_per_jiffy;
  77 }
  78
  79 void __init smp_prepare_cpus(unsigned int max_cpus)
  80 {
  81         unsigned int cpu = smp_processor_id();
  82         int i;
  83
  84         atomic_set(&cpus_booted, 1);
  85         smp_store_cpu_info(cpu);
  86
  87         for (i = 0; i < __smp_probe_cpus(); i++)
  88                 cpu_set(i, cpu_possible_map);
  89 }
  90
  91 void __devinit smp_prepare_boot_cpu(void)
  92 {
  93         unsigned int cpu = smp_processor_id();
  94
  95         cpu_set(cpu, cpu_online_map);
  96         cpu_set(cpu, cpu_possible_map);
  97 }
  98
  99 int __cpu_up(unsigned int cpu)
 100 {
 101         struct task_struct *tsk;
 102
 103         tsk = fork_idle(cpu);
 104
 105         if (IS_ERR(tsk))
 106                 panic("Failed forking idle task for cpu %d\n", cpu);
 107
 108         task_thread_info(tsk)->cpu = cpu;
 109
 110         cpu_set(cpu, cpu_online_map);
 111
 112         return 0;
 113 }
 114
 115 int start_secondary(void *unused)
 116 {
 117         unsigned int cpu;
 118
 119         cpu = smp_processor_id();
 120
 121         atomic_inc(&init_mm.mm_count);
 122         current->active_mm = &init_mm;
 123
 124         smp_store_cpu_info(cpu);
 125
 126         __smp_slave_init(cpu);
 127         preempt_disable();
 128         per_cpu_trap_init();
 129
 130         atomic_inc(&cpus_booted);
 131
 132         cpu_idle();
 133         return 0;
 134 }
 135
 136 void __init smp_cpus_done(unsigned int max_cpus)
 137 {
 138         smp_mb();
 139 }
 140
 141 void smp_send_reschedule(int cpu)
 142 {
 143         __smp_send_ipi(cpu, SMP_MSG_RESCHEDULE);
 144 }
 145
 146 static void stop_this_cpu(void *unused)
 147 {
 148         cpu_clear(smp_processor_id(), cpu_online_map);
 149         local_irq_disable();
 150
 151         for (;;)
 152                 cpu_relax();
 153 }
 154
 155 void smp_send_stop(void)
 156 {
 157         smp_call_function(stop_this_cpu, 0, 1, 0);
 158 }
 159
 160
 161 struct smp_fn_call_struct smp_fn_call = {
 162         .lock           = SPIN_LOCK_UNLOCKED,
 163         .finished       = ATOMIC_INIT(0),
 164 };
 165
 166 /*
 167  * The caller of this wants the passed function to run on every cpu.  If wait
 168  * is set, wait until all cpus have finished the function before returning.
 169  * The lock is here to protect the call structure.
 170  * You must not call this function with disabled interrupts or from a
 171  * hardware interrupt handler or from a bottom half handler.
 172  */
 173 int smp_call_function(void (*func)(void *info), void *info, int retry, int wait)
 174 {
 175         unsigned int nr_cpus = atomic_read(&cpus_booted);
 176         int i;
 177
 178         if (nr_cpus < 2)
 179                 return 0;
 180
 181         /* Can deadlock when called with interrupts disabled */
 182         WARN_ON(irqs_disabled());
 183
 184         spin_lock(&smp_fn_call.lock);
 185
 186         atomic_set(&smp_fn_call.finished, 0);
 187         smp_fn_call.fn = func;
 188         smp_fn_call.data = info;
 189
 190         for (i = 0; i < nr_cpus; i++)
 191                 if (i != smp_processor_id())
 192                         __smp_call_function(i);
 193
 194         if (wait)
 195                 while (atomic_read(&smp_fn_call.finished) != (nr_cpus - 1));
 196
 197         spin_unlock(&smp_fn_call.lock);
 198
 199         return 0;
 200 }
 201
 202 /* Not really SMP stuff ... */
 203 int setup_profiling_timer(unsigned int multiplier)
 204 {
 205         return 0;
 206 }
 207