arch/powerpc/platforms/cell/smp.c

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