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 #undef DEBUG
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/sched.h>
  20 #include <linux/smp.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/delay.h>
  23 #include <linux/init.h>
  24 #include <linux/spinlock.h>
  25 #include <linux/cache.h>
  26 #include <linux/err.h>
  27 #include <linux/sysdev.h>
  28 #include <linux/cpu.h>
  29
  30 #include <asm/ptrace.h>
  31 #include <asm/atomic.h>
  32 #include <asm/irq.h>
  33 #include <asm/page.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/io.h>
  36 #include <asm/prom.h>
  37 #include <asm/smp.h>
  38 #include <asm/paca.h>
  39 #include <asm/time.h>
  40 #include <asm/machdep.h>
  41 #include "xics.h"
  42 #include <asm/cputable.h>
  43 #include <asm/firmware.h>
  44 #include <asm/system.h>
  45 #include <asm/rtas.h>
  46 #include <asm/pSeries_reconfig.h>
  47 #include <asm/mpic.h>
  48 #include <asm/vdso_datapage.h>
  49 #include <asm/cputhreads.h>
  50
  51 #include "plpar_wrappers.h"
  52 #include "pseries.h"
  53
  54 #ifdef DEBUG
  55 #include <asm/udbg.h>
  56 #define DBG(fmt...) udbg_printf(fmt)
  57 #else
  58 #define DBG(fmt...)
  59 #endif
  60
  61 /*
  62  * The primary thread of each non-boot processor is recorded here before
  63  * smp init.
  64  */
  65 static cpumask_t of_spin_map;
  66
  67 extern void generic_secondary_smp_init(unsigned long);
  68
  69 /**
  70  * smp_startup_cpu() - start the given cpu
  71  *
  72  * At boot time, there is nothing to do for primary threads which were
  73  * started from Open Firmware.  For anything else, call RTAS with the
  74  * appropriate start location.
  75  *
  76  * Returns:
  77  *      0       - failure
  78  *      1       - success
  79  */
  80 static inline int __devinit smp_startup_cpu(unsigned int lcpu)
  81 {
  82         int status;
  83         unsigned long start_here = __pa((u32)*((unsigned long *)
  84                                                generic_secondary_smp_init));
  85         unsigned int pcpu;
  86         int start_cpu;
  87
  88         if (cpu_isset(lcpu, of_spin_map))
  89                 /* Already started by OF and sitting in spin loop */
  90                 return 1;
  91
  92         pcpu = get_hard_smp_processor_id(lcpu);
  93
  94         /* Fixup atomic count: it exited inside IRQ handler. */
  95         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
  96
  97         /*
  98          * If the RTAS start-cpu token does not exist then presume the
  99          * cpu is already spinning.
 100          */
 101         start_cpu = rtas_token("start-cpu");
 102         if (start_cpu == RTAS_UNKNOWN_SERVICE)
 103                 return 1;
 104
 105         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
 106         if (status != 0) {
 107                 printk(KERN_ERR "start-cpu failed: %i\n", status);
 108                 return 0;
 109         }
 110
 111         return 1;
 112 }
 113
 114 #ifdef CONFIG_XICS
 115 static inline void smp_xics_do_message(int cpu, int msg)
 116 {
 117         set_bit(msg, &xics_ipi_message[cpu].value);
 118         mb();
 119         xics_cause_IPI(cpu);
 120 }
 121
 122 static void smp_xics_message_pass(int target, int msg)
 123 {
 124         unsigned int i;
 125
 126         if (target < NR_CPUS) {
 127                 smp_xics_do_message(target, msg);
 128         } else {
 129                 for_each_online_cpu(i) {
 130                         if (target == MSG_ALL_BUT_SELF
 131                             && i == smp_processor_id())
 132                                 continue;
 133                         smp_xics_do_message(i, msg);
 134                 }
 135         }
 136 }
 137
 138 static int __init smp_xics_probe(void)
 139 {
 140         xics_request_IPIs();
 141
 142         return cpus_weight(cpu_possible_map);
 143 }
 144
 145 static void __devinit smp_xics_setup_cpu(int cpu)
 146 {
 147         if (cpu != boot_cpuid)
 148                 xics_setup_cpu();
 149
 150         if (firmware_has_feature(FW_FEATURE_SPLPAR))
 151                 vpa_init(cpu);
 152
 153         cpu_clear(cpu, of_spin_map);
 154
 155 }
 156 #endif /* CONFIG_XICS */
 157
 158 static DEFINE_SPINLOCK(timebase_lock);
 159 static unsigned long timebase = 0;
 160
 161 static void __devinit pSeries_give_timebase(void)
 162 {
 163         spin_lock(&timebase_lock);
 164         rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
 165         timebase = get_tb();
 166         spin_unlock(&timebase_lock);
 167
 168         while (timebase)
 169                 barrier();
 170         rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
 171 }
 172
 173 static void __devinit pSeries_take_timebase(void)
 174 {
 175         while (!timebase)
 176                 barrier();
 177         spin_lock(&timebase_lock);
 178         set_tb(timebase >> 32, timebase & 0xffffffff);
 179         timebase = 0;
 180         spin_unlock(&timebase_lock);
 181 }
 182
 183 static void __devinit smp_pSeries_kick_cpu(int nr)
 184 {
 185         BUG_ON(nr < 0 || nr >= NR_CPUS);
 186
 187         if (!smp_startup_cpu(nr))
 188                 return;
 189
 190         /*
 191          * The processor is currently spinning, waiting for the
 192          * cpu_start field to become non-zero After we set cpu_start,
 193          * the processor will continue on to secondary_start
 194          */
 195         paca[nr].cpu_start = 1;
 196 }
 197
 198 static int smp_pSeries_cpu_bootable(unsigned int nr)
 199 {
 200         /* Special case - we inhibit secondary thread startup
 201          * during boot if the user requests it.  Odd-numbered
 202          * cpus are assumed to be secondary threads.
 203          */
 204         if (system_state < SYSTEM_RUNNING &&
 205             cpu_has_feature(CPU_FTR_SMT) &&
 206             !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
 207                 return 0;
 208
 209         return 1;
 210 }
 211 #ifdef CONFIG_MPIC
 212 static struct smp_ops_t pSeries_mpic_smp_ops = {
 213         .message_pass   = smp_mpic_message_pass,
 214         .probe          = smp_mpic_probe,
 215         .kick_cpu       = smp_pSeries_kick_cpu,
 216         .setup_cpu      = smp_mpic_setup_cpu,
 217 };
 218 #endif
 219 #ifdef CONFIG_XICS
 220 static struct smp_ops_t pSeries_xics_smp_ops = {
 221         .message_pass   = smp_xics_message_pass,
 222         .probe          = smp_xics_probe,
 223         .kick_cpu       = smp_pSeries_kick_cpu,
 224         .setup_cpu      = smp_xics_setup_cpu,
 225         .cpu_bootable   = smp_pSeries_cpu_bootable,
 226 };
 227 #endif
 228
 229 /* This is called very early */
 230 static void __init smp_init_pseries(void)
 231 {
 232         int i;
 233
 234         DBG(" -> smp_init_pSeries()\n");
 235
 236         /* Mark threads which are still spinning in hold loops. */
 237         if (cpu_has_feature(CPU_FTR_SMT)) {
 238                 for_each_present_cpu(i) {
 239                         if (i % 2 == 0)
 240                                 /*
 241                                  * Even-numbered logical cpus correspond to
 242                                  * primary threads.
 243                                  */
 244                                 cpu_set(i, of_spin_map);
 245                 }
 246         } else {
 247                 of_spin_map = cpu_present_map;
 248         }
 249
 250         cpu_clear(boot_cpuid, of_spin_map);
 251
 252         /* Non-lpar has additional take/give timebase */
 253         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 254                 smp_ops->give_timebase = pSeries_give_timebase;
 255                 smp_ops->take_timebase = pSeries_take_timebase;
 256         }
 257
 258         DBG(" <- smp_init_pSeries()\n");
 259 }
 260
 261 #ifdef CONFIG_MPIC
 262 void __init smp_init_pseries_mpic(void)
 263 {
 264         smp_ops = &pSeries_mpic_smp_ops;
 265
 266         smp_init_pseries();
 267 }
 268 #endif
 269
 270 void __init smp_init_pseries_xics(void)
 271 {
 272         smp_ops = &pSeries_xics_smp_ops;
 273
 274         smp_init_pseries();
 275 }