arch/powerpc/platforms/pseries/smp.c

   1 /*
   2  * SMP support for pSeries machines.
   3  *
   4  * Dave Engebretsen, Peter Bergner, and
   5  * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
   6  *
   7  * Plus various changes from other IBM teams...
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  */
  14
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/sched.h>
  19 #include <linux/smp.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/delay.h>
  22 #include <linux/init.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/cache.h>
  25 #include <linux/err.h>
  26 #include <linux/sysdev.h>
  27 #include <linux/cpu.h>
  28
  29 #include <asm/ptrace.h>
  30 #include <asm/atomic.h>
  31 #include <asm/irq.h>
  32 #include <asm/page.h>
  33 #include <asm/pgtable.h>
  34 #include <asm/io.h>
  35 #include <asm/prom.h>
  36 #include <asm/smp.h>
  37 #include <asm/paca.h>
  38 #include <asm/time.h>
  39 #include <asm/machdep.h>
  40 #include <asm/cputable.h>
  41 #include <asm/firmware.h>
  42 #include <asm/system.h>
  43 #include <asm/rtas.h>
  44 #include <asm/pSeries_reconfig.h>
  45 #include <asm/mpic.h>
  46 #include <asm/vdso_datapage.h>
  47 #include <asm/cputhreads.h>
  48
  49 #include "plpar_wrappers.h"
  50 #include "pseries.h"
  51 #include "xics.h"
  52
  53
  54 /*
  55  * The primary thread of each non-boot processor is recorded here before
  56  * smp init.
  57  */
  58 static cpumask_t of_spin_map;
  59
  60 extern void generic_secondary_smp_init(unsigned long);
  61
  62 /**
  63  * smp_startup_cpu() - start the given cpu
  64  *
  65  * At boot time, there is nothing to do for primary threads which were
  66  * started from Open Firmware.  For anything else, call RTAS with the
  67  * appropriate start location.
  68  *
  69  * Returns:
  70  *      0       - failure
  71  *      1       - success
  72  */
  73 static inline int __devinit smp_startup_cpu(unsigned int lcpu)
  74 {
  75         int status;
  76         unsigned long start_here = __pa((u32)*((unsigned long *)
  77                                                generic_secondary_smp_init));
  78         unsigned int pcpu;
  79         int start_cpu;
  80
  81         if (cpu_isset(lcpu, of_spin_map))
  82                 /* Already started by OF and sitting in spin loop */
  83                 return 1;
  84
  85         pcpu = get_hard_smp_processor_id(lcpu);
  86
  87         /* Fixup atomic count: it exited inside IRQ handler. */
  88         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
  89
  90         /*
  91          * If the RTAS start-cpu token does not exist then presume the
  92          * cpu is already spinning.
  93          */
  94         start_cpu = rtas_token("start-cpu");
  95         if (start_cpu == RTAS_UNKNOWN_SERVICE)
  96                 return 1;
  97
  98         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
  99         if (status != 0) {
 100                 printk(KERN_ERR "start-cpu failed: %i\n", status);
 101                 return 0;
 102         }
 103
 104         return 1;
 105 }
 106
 107 #ifdef CONFIG_XICS
 108 static void __devinit smp_xics_setup_cpu(int cpu)
 109 {
 110         if (cpu != boot_cpuid)
 111                 xics_setup_cpu();
 112
 113         if (firmware_has_feature(FW_FEATURE_SPLPAR))
 114                 vpa_init(cpu);
 115
 116         cpu_clear(cpu, of_spin_map);
 117
 118 }
 119 #endif /* CONFIG_XICS */
 120
 121 static DEFINE_SPINLOCK(timebase_lock);
 122 static unsigned long timebase = 0;
 123
 124 static void __devinit pSeries_give_timebase(void)
 125 {
 126         spin_lock(&timebase_lock);
 127         rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
 128         timebase = get_tb();
 129         spin_unlock(&timebase_lock);
 130
 131         while (timebase)
 132                 barrier();
 133         rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
 134 }
 135
 136 static void __devinit pSeries_take_timebase(void)
 137 {
 138         while (!timebase)
 139                 barrier();
 140         spin_lock(&timebase_lock);
 141         set_tb(timebase >> 32, timebase & 0xffffffff);
 142         timebase = 0;
 143         spin_unlock(&timebase_lock);
 144 }
 145
 146 static void __devinit smp_pSeries_kick_cpu(int nr)
 147 {
 148         BUG_ON(nr < 0 || nr >= NR_CPUS);
 149
 150         if (!smp_startup_cpu(nr))
 151                 return;
 152
 153         /*
 154          * The processor is currently spinning, waiting for the
 155          * cpu_start field to become non-zero After we set cpu_start,
 156          * the processor will continue on to secondary_start
 157          */
 158         paca[nr].cpu_start = 1;
 159 }
 160
 161 static int smp_pSeries_cpu_bootable(unsigned int nr)
 162 {
 163         /* Special case - we inhibit secondary thread startup
 164          * during boot if the user requests it.  Odd-numbered
 165          * cpus are assumed to be secondary threads.
 166          */
 167         if (system_state < SYSTEM_RUNNING &&
 168             cpu_has_feature(CPU_FTR_SMT) &&
 169             !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
 170                 return 0;
 171
 172         return 1;
 173 }
 174 #ifdef CONFIG_MPIC
 175 static struct smp_ops_t pSeries_mpic_smp_ops = {
 176         .message_pass   = smp_mpic_message_pass,
 177         .probe          = smp_mpic_probe,
 178         .kick_cpu       = smp_pSeries_kick_cpu,
 179         .setup_cpu      = smp_mpic_setup_cpu,
 180 };
 181 #endif
 182 #ifdef CONFIG_XICS
 183 static struct smp_ops_t pSeries_xics_smp_ops = {
 184         .message_pass   = smp_xics_message_pass,
 185         .probe          = smp_xics_probe,
 186         .kick_cpu       = smp_pSeries_kick_cpu,
 187         .setup_cpu      = smp_xics_setup_cpu,
 188         .cpu_bootable   = smp_pSeries_cpu_bootable,
 189 };
 190 #endif
 191
 192 /* This is called very early */
 193 static void __init smp_init_pseries(void)
 194 {
 195         int i;
 196
 197         pr_debug(" -> smp_init_pSeries()\n");
 198
 199         /* Mark threads which are still spinning in hold loops. */
 200         if (cpu_has_feature(CPU_FTR_SMT)) {
 201                 for_each_present_cpu(i) {
 202                         if (i % 2 == 0)
 203                                 /*
 204                                  * Even-numbered logical cpus correspond to
 205                                  * primary threads.
 206                                  */
 207                                 cpu_set(i, of_spin_map);
 208                 }
 209         } else {
 210                 of_spin_map = cpu_present_map;
 211         }
 212
 213         cpu_clear(boot_cpuid, of_spin_map);
 214
 215         /* Non-lpar has additional take/give timebase */
 216         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 217                 smp_ops->give_timebase = pSeries_give_timebase;
 218                 smp_ops->take_timebase = pSeries_take_timebase;
 219         }
 220
 221         pr_debug(" <- smp_init_pSeries()\n");
 222 }
 223
 224 #ifdef CONFIG_MPIC
 225 void __init smp_init_pseries_mpic(void)
 226 {
 227         smp_ops = &pSeries_mpic_smp_ops;
 228
 229         smp_init_pseries();
 230 }
 231 #endif
 232
 233 void __init smp_init_pseries_xics(void)
 234 {
 235         smp_ops = &pSeries_xics_smp_ops;
 236
 237         smp_init_pseries();
 238 }