arch/powerpc/platforms/powernv/smp.c

   1 /*
   2  * SMP support for PowerNV machines.
   3  *
   4  * Copyright 2011 IBM Corp.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/sched.h>
  15 #include <linux/smp.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/delay.h>
  18 #include <linux/init.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/cpu.h>
  21
  22 #include <asm/irq.h>
  23 #include <asm/smp.h>
  24 #include <asm/paca.h>
  25 #include <asm/machdep.h>
  26 #include <asm/cputable.h>
  27 #include <asm/firmware.h>
  28 #include <asm/system.h>
  29 #include <asm/rtas.h>
  30 #include <asm/vdso_datapage.h>
  31 #include <asm/cputhreads.h>
  32 #include <asm/xics.h>
  33 #include <asm/opal.h>
  34
  35 #include "powernv.h"
  36
  37 #ifdef DEBUG
  38 #include <asm/udbg.h>
  39 #define DBG(fmt...) udbg_printf(fmt)
  40 #else
  41 #define DBG(fmt...)
  42 #endif
  43
  44 static void __cpuinit pnv_smp_setup_cpu(int cpu)
  45 {
  46         if (cpu != boot_cpuid)
  47                 xics_setup_cpu();
  48 }
  49
  50 static int pnv_smp_cpu_bootable(unsigned int nr)
  51 {
  52         /* Special case - we inhibit secondary thread startup
  53          * during boot if the user requests it.
  54          */
  55         if (system_state < SYSTEM_RUNNING && cpu_has_feature(CPU_FTR_SMT)) {
  56                 if (!smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
  57                         return 0;
  58                 if (smt_enabled_at_boot
  59                     && cpu_thread_in_core(nr) >= smt_enabled_at_boot)
  60                         return 0;
  61         }
  62
  63         return 1;
  64 }
  65
  66 int __devinit pnv_smp_kick_cpu(int nr)
  67 {
  68         unsigned int pcpu = get_hard_smp_processor_id(nr);
  69         unsigned long start_here = __pa(*((unsigned long *)
  70                                           generic_secondary_smp_init));
  71         long rc;
  72
  73         BUG_ON(nr < 0 || nr >= NR_CPUS);
  74
  75         /* On OPAL v2 the CPU are still spinning inside OPAL itself,
  76          * get them back now
  77          */
  78         if (!paca[nr].cpu_start && firmware_has_feature(FW_FEATURE_OPALv2)) {
  79                 pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n", nr, pcpu);
  80                 rc = opal_start_cpu(pcpu, start_here);
  81                 if (rc != OPAL_SUCCESS)
  82                         pr_warn("OPAL Error %ld starting CPU %d\n",
  83                                 rc, nr);
  84         }
  85         return smp_generic_kick_cpu(nr);
  86 }
  87
  88 #ifdef CONFIG_HOTPLUG_CPU
  89
  90 static int pnv_smp_cpu_disable(void)
  91 {
  92         int cpu = smp_processor_id();
  93
  94         /* This is identical to pSeries... might consolidate by
  95          * moving migrate_irqs_away to a ppc_md with default to
  96          * the generic fixup_irqs. --BenH.
  97          */
  98         set_cpu_online(cpu, false);
  99         vdso_data->processorCount--;
 100         if (cpu == boot_cpuid)
 101                 boot_cpuid = cpumask_any(cpu_online_mask);
 102         xics_migrate_irqs_away();
 103         return 0;
 104 }
 105
 106 static void pnv_smp_cpu_kill_self(void)
 107 {
 108         unsigned int cpu;
 109
 110         /* If powersave_nap is enabled, use NAP mode, else just
 111          * spin aimlessly
 112          */
 113         if (!powersave_nap) {
 114                 generic_mach_cpu_die();
 115                 return;
 116         }
 117
 118         /* Standard hot unplug procedure */
 119         local_irq_disable();
 120         idle_task_exit();
 121         current->active_mm = NULL; /* for sanity */
 122         cpu = smp_processor_id();
 123         DBG("CPU%d offline\n", cpu);
 124         generic_set_cpu_dead(cpu);
 125         smp_wmb();
 126
 127         /* We don't want to take decrementer interrupts while we are offline,
 128          * so clear LPCR:PECE1. We keep PECE2 enabled.
 129          */
 130         mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
 131         while (!generic_check_cpu_restart(cpu)) {
 132                 power7_idle();
 133                 if (!generic_check_cpu_restart(cpu)) {
 134                         DBG("CPU%d Unexpected exit while offline !\n", cpu);
 135                         /* We may be getting an IPI, so we re-enable
 136                          * interrupts to process it, it will be ignored
 137                          * since we aren't online (hopefully)
 138                          */
 139                         local_irq_enable();
 140                         local_irq_disable();
 141                 }
 142         }
 143         mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
 144         DBG("CPU%d coming online...\n", cpu);
 145 }
 146
 147 #endif /* CONFIG_HOTPLUG_CPU */
 148
 149 static struct smp_ops_t pnv_smp_ops = {
 150         .message_pass   = smp_muxed_ipi_message_pass,
 151         .cause_ipi      = NULL, /* Filled at runtime by xics_smp_probe() */
 152         .probe          = xics_smp_probe,
 153         .kick_cpu       = pnv_smp_kick_cpu,
 154         .setup_cpu      = pnv_smp_setup_cpu,
 155         .cpu_bootable   = pnv_smp_cpu_bootable,
 156 #ifdef CONFIG_HOTPLUG_CPU
 157         .cpu_disable    = pnv_smp_cpu_disable,
 158         .cpu_die        = generic_cpu_die,
 159 #endif /* CONFIG_HOTPLUG_CPU */
 160 };
 161
 162 /* This is called very early during platform setup_arch */
 163 void __init pnv_smp_init(void)
 164 {
 165         smp_ops = &pnv_smp_ops;
 166
 167         /* XXX We don't yet have a proper entry point from HAL, for
 168          * now we rely on kexec-style entry from BML
 169          */
 170
 171 #ifdef CONFIG_PPC_RTAS
 172         /* Non-lpar has additional take/give timebase */
 173         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 174                 smp_ops->give_timebase = rtas_give_timebase;
 175                 smp_ops->take_timebase = rtas_take_timebase;
 176         }
 177 #endif /* CONFIG_PPC_RTAS */
 178
 179 #ifdef CONFIG_HOTPLUG_CPU
 180         ppc_md.cpu_die  = pnv_smp_cpu_kill_self;
 181 #endif
 182 }