sysfs.c

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#include <linux/device.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/export.h>
#include <linux/nodemask.h>
#include <linux/cpumask.h>
#include <linux/notifier.h>

#include <asm/current.h>
#include <asm/processor.h>
#include <asm/cputable.h>
#include <asm/hvcall.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/smp.h>
#include <asm/pmc.h>

#include "cacheinfo.h"

#ifdef CONFIG_PPC64
#include <asm/paca.h>
#include <asm/lppaca.h>
#endif

static DEFINE_PER_CPU(struct cpu, cpu_devices);

/*
 * SMT snooze delay stuff, 64-bit only for now
 */

#ifdef CONFIG_PPC64

/* Time in microseconds we delay before sleeping in the idle loop */
DEFINE_PER_CPU(long, smt_snooze_delay) = { 100 };

static ssize_t store_smt_snooze_delay(struct device *dev,
                      struct device_attribute *attr,
                      const char *buf,
                      size_t count)
{
    struct cpu *cpu = container_of(dev, struct cpu, dev);
    ssize_t ret;
    long snooze;

    ret = sscanf(buf, "%ld", &snooze);
    if (ret != 1)
        return -EINVAL;

    per_cpu(smt_snooze_delay, cpu->dev.id) = snooze;
    update_smt_snooze_delay(cpu->dev.id, snooze);

    return count;
}

static ssize_t show_smt_snooze_delay(struct device *dev,
                     struct device_attribute *attr,
                     char *buf)
{
    struct cpu *cpu = container_of(dev, struct cpu, dev);

    return sprintf(buf, "%ld\n", per_cpu(smt_snooze_delay, cpu->dev.id));
}

static DEVICE_ATTR(smt_snooze_delay, 0644, show_smt_snooze_delay,
           store_smt_snooze_delay);

static int __init setup_smt_snooze_delay(char *str)
{
    unsigned int cpu;
    long snooze;

    if (!cpu_has_feature(CPU_FTR_SMT))
        return 1;

    snooze = simple_strtol(str, NULL, 10);
    for_each_possible_cpu(cpu)
        per_cpu(smt_snooze_delay, cpu) = snooze;

    return 1;
}
__setup("smt-snooze-delay=", setup_smt_snooze_delay);

#endif /* CONFIG_PPC64 */

/*
 * Enabling PMCs will slow partition context switch times so we only do
 * it the first time we write to the PMCs.
 */

static DEFINE_PER_CPU(char, pmcs_enabled);

void ppc_enable_pmcs(void)
{
    ppc_set_pmu_inuse(1);

    /* Only need to enable them once */
    if (__get_cpu_var(pmcs_enabled))
        return;

    __get_cpu_var(pmcs_enabled) = 1;

    if (ppc_md.enable_pmcs)
        ppc_md.enable_pmcs();
}
EXPORT_SYMBOL(ppc_enable_pmcs);

#define SYSFS_PMCSETUP(NAME, ADDRESS) \
static void read_##NAME(void *val) \
{ \
    *(unsigned long *)val = mfspr(ADDRESS); \
} \
static void write_##NAME(void *val) \
{ \
    ppc_enable_pmcs(); \
    mtspr(ADDRESS, *(unsigned long *)val);  \
} \
static ssize_t show_##NAME(struct device *dev, \
            struct device_attribute *attr, \
            char *buf) \
{ \
    struct cpu *cpu = container_of(dev, struct cpu, dev); \
    unsigned long val; \
    smp_call_function_single(cpu->dev.id, read_##NAME, &val, 1);    \
    return sprintf(buf, "%lx\n", val); \
} \
static ssize_t __used \
    store_##NAME(struct device *dev, struct device_attribute *attr, \
            const char *buf, size_t count) \
{ \
    struct cpu *cpu = container_of(dev, struct cpu, dev); \
    unsigned long val; \
    int ret = sscanf(buf, "%lx", &val); \
    if (ret != 1) \
        return -EINVAL; \
    smp_call_function_single(cpu->dev.id, write_##NAME, &val, 1); \
    return count; \
}


/* Let's define all possible registers, we'll only hook up the ones
 * that are implemented on the current processor
 */

#if defined(CONFIG_PPC64)
#define HAS_PPC_PMC_CLASSIC 1
#define HAS_PPC_PMC_IBM     1
#define HAS_PPC_PMC_PA6T    1
#elif defined(CONFIG_6xx)
#define HAS_PPC_PMC_CLASSIC 1
#define HAS_PPC_PMC_IBM     1
#define HAS_PPC_PMC_G4      1
#endif


#ifdef HAS_PPC_PMC_CLASSIC
SYSFS_PMCSETUP(mmcr0, SPRN_MMCR0);
SYSFS_PMCSETUP(mmcr1, SPRN_MMCR1);
SYSFS_PMCSETUP(pmc1, SPRN_PMC1);
SYSFS_PMCSETUP(pmc2, SPRN_PMC2);
SYSFS_PMCSETUP(pmc3, SPRN_PMC3);
SYSFS_PMCSETUP(pmc4, SPRN_PMC4);
SYSFS_PMCSETUP(pmc5, SPRN_PMC5);
SYSFS_PMCSETUP(pmc6, SPRN_PMC6);

#ifdef HAS_PPC_PMC_G4
SYSFS_PMCSETUP(mmcr2, SPRN_MMCR2);
#endif

#ifdef CONFIG_PPC64
SYSFS_PMCSETUP(pmc7, SPRN_PMC7);
SYSFS_PMCSETUP(pmc8, SPRN_PMC8);

SYSFS_PMCSETUP(mmcra, SPRN_MMCRA);
SYSFS_PMCSETUP(purr, SPRN_PURR);
SYSFS_PMCSETUP(spurr, SPRN_SPURR);
SYSFS_PMCSETUP(dscr, SPRN_DSCR);
SYSFS_PMCSETUP(pir, SPRN_PIR);

static DEVICE_ATTR(mmcra, 0600, show_mmcra, store_mmcra);
static DEVICE_ATTR(spurr, 0600, show_spurr, NULL);
static DEVICE_ATTR(dscr, 0600, show_dscr, store_dscr);
static DEVICE_ATTR(purr, 0600, show_purr, store_purr);
static DEVICE_ATTR(pir, 0400, show_pir, NULL);

unsigned long dscr_default = 0;
EXPORT_SYMBOL(dscr_default);

static ssize_t show_dscr_default(struct device *dev,
        struct device_attribute *attr, char *buf)
{
    return sprintf(buf, "%lx\n", dscr_default);
}

static void update_dscr(void *dummy)
{
    if (!current->thread.dscr_inherit) {
        current->thread.dscr = dscr_default;
        mtspr(SPRN_DSCR, dscr_default);
    }
}

static ssize_t __used store_dscr_default(struct device *dev,
        struct device_attribute *attr, const char *buf,
        size_t count)
{
    unsigned long val;
    int ret = 0;
    
    ret = sscanf(buf, "%lx", &val);
    if (ret != 1)
        return -EINVAL;
    dscr_default = val;

    on_each_cpu(update_dscr, NULL, 1);

    return count;
}

static DEVICE_ATTR(dscr_default, 0600,
        show_dscr_default, store_dscr_default);

static void sysfs_create_dscr_default(void)
{
    int err = 0;
    if (cpu_has_feature(CPU_FTR_DSCR))
        err = device_create_file(cpu_subsys.dev_root, &dev_attr_dscr_default);
}
#endif /* CONFIG_PPC64 */

#ifdef HAS_PPC_PMC_PA6T
SYSFS_PMCSETUP(pa6t_pmc0, SPRN_PA6T_PMC0);
SYSFS_PMCSETUP(pa6t_pmc1, SPRN_PA6T_PMC1);
SYSFS_PMCSETUP(pa6t_pmc2, SPRN_PA6T_PMC2);
SYSFS_PMCSETUP(pa6t_pmc3, SPRN_PA6T_PMC3);
SYSFS_PMCSETUP(pa6t_pmc4, SPRN_PA6T_PMC4);
SYSFS_PMCSETUP(pa6t_pmc5, SPRN_PA6T_PMC5);
#ifdef CONFIG_DEBUG_KERNEL
SYSFS_PMCSETUP(hid0, SPRN_HID0);
SYSFS_PMCSETUP(hid1, SPRN_HID1);
SYSFS_PMCSETUP(hid4, SPRN_HID4);
SYSFS_PMCSETUP(hid5, SPRN_HID5);
SYSFS_PMCSETUP(ima0, SPRN_PA6T_IMA0);
SYSFS_PMCSETUP(ima1, SPRN_PA6T_IMA1);
SYSFS_PMCSETUP(ima2, SPRN_PA6T_IMA2);
SYSFS_PMCSETUP(ima3, SPRN_PA6T_IMA3);
SYSFS_PMCSETUP(ima4, SPRN_PA6T_IMA4);
SYSFS_PMCSETUP(ima5, SPRN_PA6T_IMA5);
SYSFS_PMCSETUP(ima6, SPRN_PA6T_IMA6);
SYSFS_PMCSETUP(ima7, SPRN_PA6T_IMA7);
SYSFS_PMCSETUP(ima8, SPRN_PA6T_IMA8);
SYSFS_PMCSETUP(ima9, SPRN_PA6T_IMA9);
SYSFS_PMCSETUP(imaat, SPRN_PA6T_IMAAT);
SYSFS_PMCSETUP(btcr, SPRN_PA6T_BTCR);
SYSFS_PMCSETUP(pccr, SPRN_PA6T_PCCR);
SYSFS_PMCSETUP(rpccr, SPRN_PA6T_RPCCR);
SYSFS_PMCSETUP(der, SPRN_PA6T_DER);
SYSFS_PMCSETUP(mer, SPRN_PA6T_MER);
SYSFS_PMCSETUP(ber, SPRN_PA6T_BER);
SYSFS_PMCSETUP(ier, SPRN_PA6T_IER);
SYSFS_PMCSETUP(sier, SPRN_PA6T_SIER);
SYSFS_PMCSETUP(siar, SPRN_PA6T_SIAR);
SYSFS_PMCSETUP(tsr0, SPRN_PA6T_TSR0);
SYSFS_PMCSETUP(tsr1, SPRN_PA6T_TSR1);
SYSFS_PMCSETUP(tsr2, SPRN_PA6T_TSR2);
SYSFS_PMCSETUP(tsr3, SPRN_PA6T_TSR3);
#endif /* CONFIG_DEBUG_KERNEL */
#endif /* HAS_PPC_PMC_PA6T */

#ifdef HAS_PPC_PMC_IBM
static struct device_attribute ibm_common_attrs[] = {
    __ATTR(mmcr0, 0600, show_mmcr0, store_mmcr0),
    __ATTR(mmcr1, 0600, show_mmcr1, store_mmcr1),
};
#endif /* HAS_PPC_PMC_G4 */

#ifdef HAS_PPC_PMC_G4
static struct device_attribute g4_common_attrs[] = {
    __ATTR(mmcr0, 0600, show_mmcr0, store_mmcr0),
    __ATTR(mmcr1, 0600, show_mmcr1, store_mmcr1),
    __ATTR(mmcr2, 0600, show_mmcr2, store_mmcr2),
};
#endif /* HAS_PPC_PMC_G4 */

static struct device_attribute classic_pmc_attrs[] = {
    __ATTR(pmc1, 0600, show_pmc1, store_pmc1),
    __ATTR(pmc2, 0600, show_pmc2, store_pmc2),
    __ATTR(pmc3, 0600, show_pmc3, store_pmc3),
    __ATTR(pmc4, 0600, show_pmc4, store_pmc4),
    __ATTR(pmc5, 0600, show_pmc5, store_pmc5),
    __ATTR(pmc6, 0600, show_pmc6, store_pmc6),
#ifdef CONFIG_PPC64
    __ATTR(pmc7, 0600, show_pmc7, store_pmc7),
    __ATTR(pmc8, 0600, show_pmc8, store_pmc8),
#endif
};

#ifdef HAS_PPC_PMC_PA6T
static struct device_attribute pa6t_attrs[] = {
    __ATTR(mmcr0, 0600, show_mmcr0, store_mmcr0),
    __ATTR(mmcr1, 0600, show_mmcr1, store_mmcr1),
    __ATTR(pmc0, 0600, show_pa6t_pmc0, store_pa6t_pmc0),
    __ATTR(pmc1, 0600, show_pa6t_pmc1, store_pa6t_pmc1),
    __ATTR(pmc2, 0600, show_pa6t_pmc2, store_pa6t_pmc2),
    __ATTR(pmc3, 0600, show_pa6t_pmc3, store_pa6t_pmc3),
    __ATTR(pmc4, 0600, show_pa6t_pmc4, store_pa6t_pmc4),
    __ATTR(pmc5, 0600, show_pa6t_pmc5, store_pa6t_pmc5),
#ifdef CONFIG_DEBUG_KERNEL
    __ATTR(hid0, 0600, show_hid0, store_hid0),
    __ATTR(hid1, 0600, show_hid1, store_hid1),
    __ATTR(hid4, 0600, show_hid4, store_hid4),
    __ATTR(hid5, 0600, show_hid5, store_hid5),
    __ATTR(ima0, 0600, show_ima0, store_ima0),
    __ATTR(ima1, 0600, show_ima1, store_ima1),
    __ATTR(ima2, 0600, show_ima2, store_ima2),
    __ATTR(ima3, 0600, show_ima3, store_ima3),
    __ATTR(ima4, 0600, show_ima4, store_ima4),
    __ATTR(ima5, 0600, show_ima5, store_ima5),
    __ATTR(ima6, 0600, show_ima6, store_ima6),
    __ATTR(ima7, 0600, show_ima7, store_ima7),
    __ATTR(ima8, 0600, show_ima8, store_ima8),
    __ATTR(ima9, 0600, show_ima9, store_ima9),
    __ATTR(imaat, 0600, show_imaat, store_imaat),
    __ATTR(btcr, 0600, show_btcr, store_btcr),
    __ATTR(pccr, 0600, show_pccr, store_pccr),
    __ATTR(rpccr, 0600, show_rpccr, store_rpccr),
    __ATTR(der, 0600, show_der, store_der),
    __ATTR(mer, 0600, show_mer, store_mer),
    __ATTR(ber, 0600, show_ber, store_ber),
    __ATTR(ier, 0600, show_ier, store_ier),
    __ATTR(sier, 0600, show_sier, store_sier),
    __ATTR(siar, 0600, show_siar, store_siar),
    __ATTR(tsr0, 0600, show_tsr0, store_tsr0),
    __ATTR(tsr1, 0600, show_tsr1, store_tsr1),
    __ATTR(tsr2, 0600, show_tsr2, store_tsr2),
    __ATTR(tsr3, 0600, show_tsr3, store_tsr3),
#endif /* CONFIG_DEBUG_KERNEL */
};
#endif /* HAS_PPC_PMC_PA6T */
#endif /* HAS_PPC_PMC_CLASSIC */

static void __cpuinit register_cpu_online(unsigned int cpu)
{
    struct cpu *c = &per_cpu(cpu_devices, cpu);
    struct device *s = &c->dev;
    struct device_attribute *attrs, *pmc_attrs;
    int i, nattrs;

#ifdef CONFIG_PPC64
    if (cpu_has_feature(CPU_FTR_SMT))
        device_create_file(s, &dev_attr_smt_snooze_delay);
#endif

    /* PMC stuff */
    switch (cur_cpu_spec->pmc_type) {
#ifdef HAS_PPC_PMC_IBM
    case PPC_PMC_IBM:
        attrs = ibm_common_attrs;
        nattrs = sizeof(ibm_common_attrs) / sizeof(struct device_attribute);
        pmc_attrs = classic_pmc_attrs;
        break;
#endif /* HAS_PPC_PMC_IBM */
#ifdef HAS_PPC_PMC_G4
    case PPC_PMC_G4:
        attrs = g4_common_attrs;
        nattrs = sizeof(g4_common_attrs) / sizeof(struct device_attribute);
        pmc_attrs = classic_pmc_attrs;
        break;
#endif /* HAS_PPC_PMC_G4 */
#ifdef HAS_PPC_PMC_PA6T
    case PPC_PMC_PA6T:
        /* PA Semi starts counting at PMC0 */
        attrs = pa6t_attrs;
        nattrs = sizeof(pa6t_attrs) / sizeof(struct device_attribute);
        pmc_attrs = NULL;
        break;
#endif /* HAS_PPC_PMC_PA6T */
    default:
        attrs = NULL;
        nattrs = 0;
        pmc_attrs = NULL;
    }

    for (i = 0; i < nattrs; i++)
        device_create_file(s, &attrs[i]);

    if (pmc_attrs)
        for (i = 0; i < cur_cpu_spec->num_pmcs; i++)
            device_create_file(s, &pmc_attrs[i]);

#ifdef CONFIG_PPC64
    if (cpu_has_feature(CPU_FTR_MMCRA))
        device_create_file(s, &dev_attr_mmcra);

    if (cpu_has_feature(CPU_FTR_PURR))
        device_create_file(s, &dev_attr_purr);

    if (cpu_has_feature(CPU_FTR_SPURR))
        device_create_file(s, &dev_attr_spurr);

    if (cpu_has_feature(CPU_FTR_DSCR))
        device_create_file(s, &dev_attr_dscr);

    if (cpu_has_feature(CPU_FTR_PPCAS_ARCH_V2))
        device_create_file(s, &dev_attr_pir);
#endif /* CONFIG_PPC64 */

    cacheinfo_cpu_online(cpu);
}

#ifdef CONFIG_HOTPLUG_CPU
static void unregister_cpu_online(unsigned int cpu)
{
    struct cpu *c = &per_cpu(cpu_devices, cpu);
    struct device *s = &c->dev;
    struct device_attribute *attrs, *pmc_attrs;
    int i, nattrs;

    BUG_ON(!c->hotpluggable);

#ifdef CONFIG_PPC64
    if (cpu_has_feature(CPU_FTR_SMT))
        device_remove_file(s, &dev_attr_smt_snooze_delay);
#endif

    /* PMC stuff */
    switch (cur_cpu_spec->pmc_type) {
#ifdef HAS_PPC_PMC_IBM
    case PPC_PMC_IBM:
        attrs = ibm_common_attrs;
        nattrs = sizeof(ibm_common_attrs) / sizeof(struct device_attribute);
        pmc_attrs = classic_pmc_attrs;
        break;
#endif /* HAS_PPC_PMC_IBM */
#ifdef HAS_PPC_PMC_G4
    case PPC_PMC_G4:
        attrs = g4_common_attrs;
        nattrs = sizeof(g4_common_attrs) / sizeof(struct device_attribute);
        pmc_attrs = classic_pmc_attrs;
        break;
#endif /* HAS_PPC_PMC_G4 */
#ifdef HAS_PPC_PMC_PA6T
    case PPC_PMC_PA6T:
        /* PA Semi starts counting at PMC0 */
        attrs = pa6t_attrs;
        nattrs = sizeof(pa6t_attrs) / sizeof(struct device_attribute);
        pmc_attrs = NULL;
        break;
#endif /* HAS_PPC_PMC_PA6T */
    default:
        attrs = NULL;
        nattrs = 0;
        pmc_attrs = NULL;
    }

    for (i = 0; i < nattrs; i++)
        device_remove_file(s, &attrs[i]);

    if (pmc_attrs)
        for (i = 0; i < cur_cpu_spec->num_pmcs; i++)
            device_remove_file(s, &pmc_attrs[i]);

#ifdef CONFIG_PPC64
    if (cpu_has_feature(CPU_FTR_MMCRA))
        device_remove_file(s, &dev_attr_mmcra);

    if (cpu_has_feature(CPU_FTR_PURR))
        device_remove_file(s, &dev_attr_purr);

    if (cpu_has_feature(CPU_FTR_SPURR))
        device_remove_file(s, &dev_attr_spurr);

    if (cpu_has_feature(CPU_FTR_DSCR))
        device_remove_file(s, &dev_attr_dscr);

    if (cpu_has_feature(CPU_FTR_PPCAS_ARCH_V2))
        device_remove_file(s, &dev_attr_pir);
#endif /* CONFIG_PPC64 */

    cacheinfo_cpu_offline(cpu);
}

#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
ssize_t arch_cpu_probe(const char *buf, size_t count)
{
    if (ppc_md.cpu_probe)
        return ppc_md.cpu_probe(buf, count);

    return -EINVAL;
}

ssize_t arch_cpu_release(const char *buf, size_t count)
{
    if (ppc_md.cpu_release)
        return ppc_md.cpu_release(buf, count);

    return -EINVAL;
}
#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */

#endif /* CONFIG_HOTPLUG_CPU */

static int __cpuinit sysfs_cpu_notify(struct notifier_block *self,
                      unsigned long action, void *hcpu)
{
    unsigned int cpu = (unsigned int)(long)hcpu;

    switch (action) {
    case CPU_ONLINE:
    case CPU_ONLINE_FROZEN:
        register_cpu_online(cpu);
        break;
#ifdef CONFIG_HOTPLUG_CPU
    case CPU_DEAD:
    case CPU_DEAD_FROZEN:
        unregister_cpu_online(cpu);
        break;
#endif
    }
    return NOTIFY_OK;
}

static struct notifier_block __cpuinitdata sysfs_cpu_nb = {
    .notifier_call  = sysfs_cpu_notify,
};

static DEFINE_MUTEX(cpu_mutex);

int cpu_add_dev_attr(struct device_attribute *attr)
{
    int cpu;

    mutex_lock(&cpu_mutex);

    for_each_possible_cpu(cpu) {
        device_create_file(get_cpu_device(cpu), attr);
    }

    mutex_unlock(&cpu_mutex);
    return 0;
}
EXPORT_SYMBOL_GPL(cpu_add_dev_attr);

int cpu_add_dev_attr_group(struct attribute_group *attrs)
{
    int cpu;
    struct device *dev;
    int ret;

    mutex_lock(&cpu_mutex);

    for_each_possible_cpu(cpu) {
        dev = get_cpu_device(cpu);
        ret = sysfs_create_group(&dev->kobj, attrs);
        WARN_ON(ret != 0);
    }

    mutex_unlock(&cpu_mutex);
    return 0;
}
EXPORT_SYMBOL_GPL(cpu_add_dev_attr_group);


void cpu_remove_dev_attr(struct device_attribute *attr)
{
    int cpu;

    mutex_lock(&cpu_mutex);

    for_each_possible_cpu(cpu) {
        device_remove_file(get_cpu_device(cpu), attr);
    }

    mutex_unlock(&cpu_mutex);
}
EXPORT_SYMBOL_GPL(cpu_remove_dev_attr);

void cpu_remove_dev_attr_group(struct attribute_group *attrs)
{
    int cpu;
    struct device *dev;

    mutex_lock(&cpu_mutex);

    for_each_possible_cpu(cpu) {
        dev = get_cpu_device(cpu);
        sysfs_remove_group(&dev->kobj, attrs);
    }

    mutex_unlock(&cpu_mutex);
}
EXPORT_SYMBOL_GPL(cpu_remove_dev_attr_group);


/* NUMA stuff */

#ifdef CONFIG_NUMA
static void register_nodes(void)
{
    int i;

    for (i = 0; i < MAX_NUMNODES; i++)
        register_one_node(i);
}

int sysfs_add_device_to_node(struct device *dev, int nid)
{
    struct node *node = &node_devices[nid];
    return sysfs_create_link(&node->dev.kobj, &dev->kobj,
            kobject_name(&dev->kobj));
}
EXPORT_SYMBOL_GPL(sysfs_add_device_to_node);

void sysfs_remove_device_from_node(struct device *dev, int nid)
{
    struct node *node = &node_devices[nid];
    sysfs_remove_link(&node->dev.kobj, kobject_name(&dev->kobj));
}
EXPORT_SYMBOL_GPL(sysfs_remove_device_from_node);

#else
static void register_nodes(void)
{
    return;
}

#endif

/* Only valid if CPU is present. */
static ssize_t show_physical_id(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    struct cpu *cpu = container_of(dev, struct cpu, dev);

    return sprintf(buf, "%d\n", get_hard_smp_processor_id(cpu->dev.id));
}
static DEVICE_ATTR(physical_id, 0444, show_physical_id, NULL);

static int __init topology_init(void)
{
    int cpu;

    register_nodes();
    register_cpu_notifier(&sysfs_cpu_nb);

    for_each_possible_cpu(cpu) {
        struct cpu *c = &per_cpu(cpu_devices, cpu);

        /*
         * For now, we just see if the system supports making
         * the RTAS calls for CPU hotplug.  But, there may be a
         * more comprehensive way to do this for an individual
         * CPU.  For instance, the boot cpu might never be valid
         * for hotplugging.
         */
        if (ppc_md.cpu_die)
            c->hotpluggable = 1;

        if (cpu_online(cpu) || c->hotpluggable) {
            register_cpu(c, cpu);

            device_create_file(&c->dev, &dev_attr_physical_id);
        }

        if (cpu_online(cpu))
            register_cpu_online(cpu);
    }
#ifdef CONFIG_PPC64
    sysfs_create_dscr_default();
#endif /* CONFIG_PPC64 */

    return 0;
}
subsys_initcall(topology_init);