linux/arch/powerpc/platforms/pseries/smp.c
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   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/sched.h>
  18#include <linux/smp.h>
  19#include <linux/interrupt.h>
  20#include <linux/delay.h>
  21#include <linux/init.h>
  22#include <linux/spinlock.h>
  23#include <linux/cache.h>
  24#include <linux/err.h>
  25#include <linux/device.h>
  26#include <linux/cpu.h>
  27
  28#include <asm/ptrace.h>
  29#include <linux/atomic.h>
  30#include <asm/irq.h>
  31#include <asm/page.h>
  32#include <asm/pgtable.h>
  33#include <asm/io.h>
  34#include <asm/prom.h>
  35#include <asm/smp.h>
  36#include <asm/paca.h>
  37#include <asm/machdep.h>
  38#include <asm/cputable.h>
  39#include <asm/firmware.h>
  40#include <asm/system.h>
  41#include <asm/rtas.h>
  42#include <asm/pSeries_reconfig.h>
  43#include <asm/mpic.h>
  44#include <asm/vdso_datapage.h>
  45#include <asm/cputhreads.h>
  46#include <asm/xics.h>
  47
  48#include "plpar_wrappers.h"
  49#include "pseries.h"
  50#include "offline_states.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 */
  57static cpumask_var_t of_spin_mask;
  58
  59/* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
  60int smp_query_cpu_stopped(unsigned int pcpu)
  61{
  62        int cpu_status, status;
  63        int qcss_tok = rtas_token("query-cpu-stopped-state");
  64
  65        if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
  66                printk_once(KERN_INFO
  67                        "Firmware doesn't support query-cpu-stopped-state\n");
  68                return QCSS_HARDWARE_ERROR;
  69        }
  70
  71        status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
  72        if (status != 0) {
  73                printk(KERN_ERR
  74                       "RTAS query-cpu-stopped-state failed: %i\n", status);
  75                return status;
  76        }
  77
  78        return cpu_status;
  79}
  80
  81/**
  82 * smp_startup_cpu() - start the given cpu
  83 *
  84 * At boot time, there is nothing to do for primary threads which were
  85 * started from Open Firmware.  For anything else, call RTAS with the
  86 * appropriate start location.
  87 *
  88 * Returns:
  89 *      0       - failure
  90 *      1       - success
  91 */
  92static inline int __devinit smp_startup_cpu(unsigned int lcpu)
  93{
  94        int status;
  95        unsigned long start_here = __pa((u32)*((unsigned long *)
  96                                               generic_secondary_smp_init));
  97        unsigned int pcpu;
  98        int start_cpu;
  99
 100        if (cpumask_test_cpu(lcpu, of_spin_mask))
 101                /* Already started by OF and sitting in spin loop */
 102                return 1;
 103
 104        pcpu = get_hard_smp_processor_id(lcpu);
 105
 106        /* Check to see if the CPU out of FW already for kexec */
 107        if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
 108                cpumask_set_cpu(lcpu, of_spin_mask);
 109                return 1;
 110        }
 111
 112        /* Fixup atomic count: it exited inside IRQ handler. */
 113        task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
 114#ifdef CONFIG_HOTPLUG_CPU
 115        if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
 116                goto out;
 117#endif
 118        /* 
 119         * If the RTAS start-cpu token does not exist then presume the
 120         * cpu is already spinning.
 121         */
 122        start_cpu = rtas_token("start-cpu");
 123        if (start_cpu == RTAS_UNKNOWN_SERVICE)
 124                return 1;
 125
 126        status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
 127        if (status != 0) {
 128                printk(KERN_ERR "start-cpu failed: %i\n", status);
 129                return 0;
 130        }
 131
 132#ifdef CONFIG_HOTPLUG_CPU
 133out:
 134#endif
 135        return 1;
 136}
 137
 138static void __devinit smp_xics_setup_cpu(int cpu)
 139{
 140        if (cpu != boot_cpuid)
 141                xics_setup_cpu();
 142
 143        if (firmware_has_feature(FW_FEATURE_SPLPAR))
 144                vpa_init(cpu);
 145
 146        cpumask_clear_cpu(cpu, of_spin_mask);
 147#ifdef CONFIG_HOTPLUG_CPU
 148        set_cpu_current_state(cpu, CPU_STATE_ONLINE);
 149        set_default_offline_state(cpu);
 150#endif
 151        pseries_notify_cpuidle_add_cpu(cpu);
 152}
 153
 154static int __devinit smp_pSeries_kick_cpu(int nr)
 155{
 156        BUG_ON(nr < 0 || nr >= NR_CPUS);
 157
 158        if (!smp_startup_cpu(nr))
 159                return -ENOENT;
 160
 161        /*
 162         * The processor is currently spinning, waiting for the
 163         * cpu_start field to become non-zero After we set cpu_start,
 164         * the processor will continue on to secondary_start
 165         */
 166        paca[nr].cpu_start = 1;
 167#ifdef CONFIG_HOTPLUG_CPU
 168        set_preferred_offline_state(nr, CPU_STATE_ONLINE);
 169
 170        if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
 171                long rc;
 172                unsigned long hcpuid;
 173
 174                hcpuid = get_hard_smp_processor_id(nr);
 175                rc = plpar_hcall_norets(H_PROD, hcpuid);
 176                if (rc != H_SUCCESS)
 177                        printk(KERN_ERR "Error: Prod to wake up processor %d "
 178                                                "Ret= %ld\n", nr, rc);
 179        }
 180#endif
 181
 182        return 0;
 183}
 184
 185static int smp_pSeries_cpu_bootable(unsigned int nr)
 186{
 187        /* Special case - we inhibit secondary thread startup
 188         * during boot if the user requests it.
 189         */
 190        if (system_state < SYSTEM_RUNNING && cpu_has_feature(CPU_FTR_SMT)) {
 191                if (!smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
 192                        return 0;
 193                if (smt_enabled_at_boot
 194                    && cpu_thread_in_core(nr) >= smt_enabled_at_boot)
 195                        return 0;
 196        }
 197
 198        return 1;
 199}
 200
 201static struct smp_ops_t pSeries_mpic_smp_ops = {
 202        .message_pass   = smp_mpic_message_pass,
 203        .probe          = smp_mpic_probe,
 204        .kick_cpu       = smp_pSeries_kick_cpu,
 205        .setup_cpu      = smp_mpic_setup_cpu,
 206};
 207
 208static struct smp_ops_t pSeries_xics_smp_ops = {
 209        .message_pass   = NULL, /* Use smp_muxed_ipi_message_pass */
 210        .cause_ipi      = NULL, /* Filled at runtime by xics_smp_probe() */
 211        .probe          = xics_smp_probe,
 212        .kick_cpu       = smp_pSeries_kick_cpu,
 213        .setup_cpu      = smp_xics_setup_cpu,
 214        .cpu_bootable   = smp_pSeries_cpu_bootable,
 215};
 216
 217/* This is called very early */
 218static void __init smp_init_pseries(void)
 219{
 220        int i;
 221
 222        pr_debug(" -> smp_init_pSeries()\n");
 223
 224        alloc_bootmem_cpumask_var(&of_spin_mask);
 225
 226        /* Mark threads which are still spinning in hold loops. */
 227        if (cpu_has_feature(CPU_FTR_SMT)) {
 228                for_each_present_cpu(i) { 
 229                        if (cpu_thread_in_core(i) == 0)
 230                                cpumask_set_cpu(i, of_spin_mask);
 231                }
 232        } else {
 233                cpumask_copy(of_spin_mask, cpu_present_mask);
 234        }
 235
 236        cpumask_clear_cpu(boot_cpuid, of_spin_mask);
 237
 238        /* Non-lpar has additional take/give timebase */
 239        if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
 240                smp_ops->give_timebase = rtas_give_timebase;
 241                smp_ops->take_timebase = rtas_take_timebase;
 242        }
 243
 244        pr_debug(" <- smp_init_pSeries()\n");
 245}
 246
 247void __init smp_init_pseries_mpic(void)
 248{
 249        smp_ops = &pSeries_mpic_smp_ops;
 250
 251        smp_init_pseries();
 252}
 253
 254void __init smp_init_pseries_xics(void)
 255{
 256        smp_ops = &pSeries_xics_smp_ops;
 257
 258        smp_init_pseries();
 259}
 260