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/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 <asm/cputable.h>
  42 #include <asm/firmware.h>
  43 #include <asm/system.h>
  44 #include <asm/rtas.h>
  45 #include <asm/cputhreads.h>
  46
  47 #include "interrupt.h"
  48 #include <asm/udbg.h>
  49
  50 #ifdef DEBUG
  51 #define DBG(fmt...) udbg_printf(fmt)
  52 #else
  53 #define DBG(fmt...)
  54 #endif
  55
  56 /*
  57  * The primary thread of each non-boot processor is recorded here before
  58  * smp init.
  59  */
  60 static cpumask_t of_spin_map;
  61
  62 extern void generic_secondary_smp_init(unsigned long);
  63
  64 /**
  65  * smp_startup_cpu() - start the given cpu
  66  *
  67  * At boot time, there is nothing to do for primary threads which were
  68  * started from Open Firmware.  For anything else, call RTAS with the
  69  * appropriate start location.
  70  *
  71  * Returns:
  72  *      0       - failure
  73  *      1       - success
  74  */
  75 static inline int __devinit smp_startup_cpu(unsigned int lcpu)
  76 {
  77         int status;
  78         unsigned long start_here = __pa((u32)*((unsigned long *)
  79                                                generic_secondary_smp_init));
  80         unsigned int pcpu;
  81         int start_cpu;
  82
  83         if (cpu_isset(lcpu, of_spin_map))
  84                 /* Already started by OF and sitting in spin loop */
  85                 return 1;
  86
  87         pcpu = get_hard_smp_processor_id(lcpu);
  88
  89         /* Fixup atomic count: it exited inside IRQ handler. */
  90         task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
  91
  92         /*
  93          * If the RTAS start-cpu token does not exist then presume the
  94          * cpu is already spinning.
  95          */
  96         start_cpu = rtas_token("start-cpu");
  97         if (start_cpu == RTAS_UNKNOWN_SERVICE)
  98                 return 1;
  99
 100         status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu);
 101         if (status != 0) {
 102                 printk(KERN_ERR "start-cpu failed: %i\n", status);
 103                 return 0;
 104         }
 105
 106         return 1;
 107 }
 108
 109 static void smp_iic_message_pass(int target, int msg)
 110 {
 111         unsigned int i;
 112
 113         if (target < NR_CPUS) {
 114                 iic_cause_IPI(target, msg);
 115         } else {
 116                 for_each_online_cpu(i) {
 117                         if (target == MSG_ALL_BUT_SELF
 118                             && i == smp_processor_id())
 119                                 continue;
 120                         iic_cause_IPI(i, msg);
 121                 }
 122         }
 123 }
 124
 125 static int __init smp_iic_probe(void)
 126 {
 127         iic_request_IPIs();
 128
 129         return cpus_weight(cpu_possible_map);
 130 }
 131
 132 static void __devinit smp_iic_setup_cpu(int cpu)
 133 {
 134         if (cpu != boot_cpuid)
 135                 iic_setup_cpu();
 136 }
 137
 138 static DEFINE_SPINLOCK(timebase_lock);
 139 static unsigned long timebase = 0;
 140
 141 static void __devinit cell_give_timebase(void)
 142 {
 143         spin_lock(&timebase_lock);
 144         rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
 145         timebase = get_tb();
 146         spin_unlock(&timebase_lock);
 147
 148         while (timebase)
 149                 barrier();
 150         rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
 151 }
 152
 153 static void __devinit cell_take_timebase(void)
 154 {
 155         while (!timebase)
 156                 barrier();
 157         spin_lock(&timebase_lock);
 158         set_tb(timebase >> 32, timebase & 0xffffffff);
 159         timebase = 0;
 160         spin_unlock(&timebase_lock);
 161 }
 162
 163 static void __devinit smp_cell_kick_cpu(int nr)
 164 {
 165         BUG_ON(nr < 0 || nr >= NR_CPUS);
 166
 167         if (!smp_startup_cpu(nr))
 168                 return;
 169
 170         /*
 171          * The processor is currently spinning, waiting for the
 172          * cpu_start field to become non-zero After we set cpu_start,
 173          * the processor will continue on to secondary_start
 174          */
 175         paca[nr].cpu_start = 1;
 176 }
 177
 178 static int smp_cell_cpu_bootable(unsigned int nr)
 179 {
 180         /* Special case - we inhibit secondary thread startup
 181          * during boot if the user requests it.  Odd-numbered
 182          * cpus are assumed to be secondary threads.
 183          */
 184         if (system_state < SYSTEM_RUNNING &&
 185             cpu_has_feature(CPU_FTR_SMT) &&
 186             !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
 187                 return 0;
 188
 189         return 1;
 190 }
 191 static struct smp_ops_t bpa_iic_smp_ops = {
 192         .message_pass   = smp_iic_message_pass,
 193         .probe          = smp_iic_probe,
 194         .kick_cpu       = smp_cell_kick_cpu,
 195         .setup_cpu      = smp_iic_setup_cpu,
 196         .cpu_bootable   = smp_cell_cpu_bootable,
 197 };
 198
 199 /* This is called very early */
 200 void __init smp_init_cell(void)
 201 {
 202         int i;
 203
 204         DBG(" -> smp_init_cell()\n");
 205
 206         smp_ops = &bpa_iic_smp_ops;
 207
 208         /* Mark threads which are still spinning in hold loops. */
 209         if (cpu_has_feature(CPU_FTR_SMT)) {
 210                 for_each_present_cpu(i) {
 211                         if (i % 2 == 0)
 212                                 /*
 213                                  * Even-numbered logical cpus correspond to
 214                                  * primary threads.
 215                                  */
 216                                 cpu_set(i, of_spin_map);
 217                 }
 218         } else {
 219                 of_spin_map = cpu_present_map;
 220         }
 221
 222         cpu_clear(boot_cpuid, of_spin_map);
 223
 224         /* Non-lpar has additional take/give timebase */
 225         if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 226                 smp_ops->give_timebase = cell_give_timebase;
 227                 smp_ops->take_timebase = cell_take_timebase;
 228         }
 229
 230         DBG(" <- smp_init_cell()\n");
 231 }