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/machdep.h>
  39 #include <asm/cputable.h>
  40 #include <asm/firmware.h>
  41 #include <asm/system.h>
  42 #include <asm/rtas.h>
  43 #include <asm/pSeries_reconfig.h>
  44 #include <asm/mpic.h>
  45 #include <asm/vdso_datapage.h>
  46 #include <asm/cputhreads.h>
  47
  48 #include "plpar_wrappers.h"
  49 #include "pseries.h"
  50 #include "xics.h"
  51
  52
  53 /*
  54  * The Primary thread of each non-boot processor was started from the OF client
  55  * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
  56  */
  57 static cpumask_t of_spin_map;
  58
  59 /**
  60  * smp_startup_cpu() - start the given cpu
  61  *
  62  * At boot time, there is nothing to do for primary threads which were
  63  * started from Open Firmware.  For anything else, call RTAS with the
  64  * appropriate start location.
  65  *
  66  * Returns:
  67  *      0       - failure
  68  *      1       - success
  69  */
  70 static inline int __devinit smp_startup_cpu(unsigned int lcpu)
  71 {
  72         int status;
  73         unsigned long start_here = __pa((u32)*((unsigned long *)
  74                                                generic_secondary_smp_init));
  75         unsigned int pcpu;
  76         int start_cpu;
  77
  78         if (cpu_isset(lcpu, of_spin_map))
  79                 /* Already started by OF and sitting in spin loop */
  80                 return 1;
  81
  82         pcpu = get_hard_smp_processor_id(lcpu);
  83
  84         /* Fixup atomic count: it exited inside IRQ handler. */
  85         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
  86
  87         /*
  88          * If the RTAS start-cpu token does not exist then presume the
  89          * cpu is already spinning.
  90          */
  91         start_cpu = rtas_token("start-cpu");
  92         if (start_cpu == RTAS_UNKNOWN_SERVICE)
  93                 return 1;
  94
  95         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
  96         if (status != 0) {
  97                 printk(KERN_ERR "start-cpu failed: %i\n", status);
  98                 return 0;
  99         }
 100
 101         return 1;
 102 }
 103
 104 #ifdef CONFIG_XICS
 105 static void __devinit smp_xics_setup_cpu(int cpu)
 106 {
 107         if (cpu != boot_cpuid)
 108                 xics_setup_cpu();
 109
 110         if (firmware_has_feature(FW_FEATURE_SPLPAR))
 111                 vpa_init(cpu);
 112
 113         cpu_clear(cpu, of_spin_map);
 114
 115 }
 116 #endif /* CONFIG_XICS */
 117
 118 static void __devinit smp_pSeries_kick_cpu(int nr)
 119 {
 120         BUG_ON(nr < 0 || nr >= NR_CPUS);
 121
 122         if (!smp_startup_cpu(nr))
 123                 return;
 124
 125         /*
 126          * The processor is currently spinning, waiting for the
 127          * cpu_start field to become non-zero After we set cpu_start,
 128          * the processor will continue on to secondary_start
 129          */
 130         paca[nr].cpu_start = 1;
 131 }
 132
 133 static int smp_pSeries_cpu_bootable(unsigned int nr)
 134 {
 135         /* Special case - we inhibit secondary thread startup
 136          * during boot if the user requests it.
 137          */
 138         if (system_state < SYSTEM_RUNNING &&
 139             cpu_has_feature(CPU_FTR_SMT) &&
 140             !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
 141                 return 0;
 142
 143         return 1;
 144 }
 145 #ifdef CONFIG_MPIC
 146 static struct smp_ops_t pSeries_mpic_smp_ops = {
 147         .message_pass   = smp_mpic_message_pass,
 148         .probe          = smp_mpic_probe,
 149         .kick_cpu       = smp_pSeries_kick_cpu,
 150         .setup_cpu      = smp_mpic_setup_cpu,
 151 };
 152 #endif
 153 #ifdef CONFIG_XICS
 154 static struct smp_ops_t pSeries_xics_smp_ops = {
 155         .message_pass   = smp_xics_message_pass,
 156         .probe          = smp_xics_probe,
 157         .kick_cpu       = smp_pSeries_kick_cpu,
 158         .setup_cpu      = smp_xics_setup_cpu,
 159         .cpu_bootable   = smp_pSeries_cpu_bootable,
 160 };
 161 #endif
 162
 163 /* This is called very early */
 164 static void __init smp_init_pseries(void)
 165 {
 166         int i;
 167
 168         pr_debug(" -> smp_init_pSeries()\n");
 169
 170         /* Mark threads which are still spinning in hold loops. */
 171         if (cpu_has_feature(CPU_FTR_SMT)) {
 172                 for_each_present_cpu(i) {
 173                         if (cpu_thread_in_core(i) == 0)
 174                                 cpu_set(i, of_spin_map);
 175                 }
 176         } else {
 177                 of_spin_map = cpu_present_map;
 178         }
 179
 180         cpu_clear(boot_cpuid, of_spin_map);
 181
 182         /* Non-lpar has additional take/give timebase */
 183         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 184                 smp_ops->give_timebase = rtas_give_timebase;
 185                 smp_ops->take_timebase = rtas_take_timebase;
 186         }
 187
 188         pr_debug(" <- smp_init_pSeries()\n");
 189 }
 190
 191 #ifdef CONFIG_MPIC
 192 void __init smp_init_pseries_mpic(void)
 193 {
 194         smp_ops = &pSeries_mpic_smp_ops;
 195
 196         smp_init_pseries();
 197 }
 198 #endif
 199
 200 void __init smp_init_pseries_xics(void)
 201 {
 202         smp_ops = &pSeries_xics_smp_ops;
 203
 204         smp_init_pseries();
 205 }