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