smp.c

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/*
 * SMP support for pSeries machines.
 *
 * Dave Engebretsen, Peter Bergner, and
 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
 *
 * Plus various changes from other IBM teams...
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */


#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/cache.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/cpu.h>

#include <asm/ptrace.h>
#include <linux/atomic.h>
#include <asm/irq.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/paca.h>
#include <asm/machdep.h>
#include <asm/cputable.h>
#include <asm/firmware.h>
#include <asm/rtas.h>
#include <asm/pSeries_reconfig.h>
#include <asm/mpic.h>
#include <asm/vdso_datapage.h>
#include <asm/cputhreads.h>
#include <asm/xics.h>

#include "plpar_wrappers.h"
#include "pseries.h"
#include "offline_states.h"


/*
 * The Primary thread of each non-boot processor was started from the OF client
 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
 */
static cpumask_var_t of_spin_mask;

/* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
int smp_query_cpu_stopped(unsigned int pcpu)
{
    int cpu_status, status;
    int qcss_tok = rtas_token("query-cpu-stopped-state");

    if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
        printk_once(KERN_INFO
            "Firmware doesn't support query-cpu-stopped-state\n");
        return QCSS_HARDWARE_ERROR;
    }

    status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
    if (status != 0) {
        printk(KERN_ERR
               "RTAS query-cpu-stopped-state failed: %i\n", status);
        return status;
    }

    return cpu_status;
}

static inline int __devinit smp_startup_cpu(unsigned int lcpu)
{
    int status;
    unsigned long start_here = __pa((u32)*((unsigned long *)
                           generic_secondary_smp_init));
    unsigned int pcpu;
    int start_cpu;

    if (cpumask_test_cpu(lcpu, of_spin_mask))
        /* Already started by OF and sitting in spin loop */
        return 1;

    pcpu = get_hard_smp_processor_id(lcpu);

    /* Check to see if the CPU out of FW already for kexec */
    if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
        cpumask_set_cpu(lcpu, of_spin_mask);
        return 1;
    }

    /* Fixup atomic count: it exited inside IRQ handler. */
    task_thread_info(paca[lcpu].__current)->preempt_count   = 0;
#ifdef CONFIG_HOTPLUG_CPU
    if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
        goto out;
#endif
    /* 
     * If the RTAS start-cpu token does not exist then presume the
     * cpu is already spinning.
     */
    start_cpu = rtas_token("start-cpu");
    if (start_cpu == RTAS_UNKNOWN_SERVICE)
        return 1;

    status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
    if (status != 0) {
        printk(KERN_ERR "start-cpu failed: %i\n", status);
        return 0;
    }

#ifdef CONFIG_HOTPLUG_CPU
out:
#endif
    return 1;
}

static void __devinit smp_xics_setup_cpu(int cpu)
{
    if (cpu != boot_cpuid)
        xics_setup_cpu();

    if (firmware_has_feature(FW_FEATURE_SPLPAR))
        vpa_init(cpu);

    cpumask_clear_cpu(cpu, of_spin_mask);
#ifdef CONFIG_HOTPLUG_CPU
    set_cpu_current_state(cpu, CPU_STATE_ONLINE);
    set_default_offline_state(cpu);
#endif
}

static int __devinit smp_pSeries_kick_cpu(int nr)
{
    BUG_ON(nr < 0 || nr >= NR_CPUS);

    if (!smp_startup_cpu(nr))
        return -ENOENT;

    /*
     * The processor is currently spinning, waiting for the
     * cpu_start field to become non-zero After we set cpu_start,
     * the processor will continue on to secondary_start
     */
    paca[nr].cpu_start = 1;
#ifdef CONFIG_HOTPLUG_CPU
    set_preferred_offline_state(nr, CPU_STATE_ONLINE);

    if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
        long rc;
        unsigned long hcpuid;

        hcpuid = get_hard_smp_processor_id(nr);
        rc = plpar_hcall_norets(H_PROD, hcpuid);
        if (rc != H_SUCCESS)
            printk(KERN_ERR "Error: Prod to wake up processor %d "
                        "Ret= %ld\n", nr, rc);
    }
#endif

    return 0;
}

static int smp_pSeries_cpu_bootable(unsigned int nr)
{
    /* Special case - we inhibit secondary thread startup
     * during boot if the user requests it.
     */
    if (system_state < SYSTEM_RUNNING && cpu_has_feature(CPU_FTR_SMT)) {
        if (!smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
            return 0;
        if (smt_enabled_at_boot
            && cpu_thread_in_core(nr) >= smt_enabled_at_boot)
            return 0;
    }

    return 1;
}

static struct smp_ops_t pSeries_mpic_smp_ops = {
    .message_pass   = smp_mpic_message_pass,
    .probe      = smp_mpic_probe,
    .kick_cpu   = smp_pSeries_kick_cpu,
    .setup_cpu  = smp_mpic_setup_cpu,
};

static struct smp_ops_t pSeries_xics_smp_ops = {
    .message_pass   = NULL, /* Use smp_muxed_ipi_message_pass */
    .cause_ipi  = NULL, /* Filled at runtime by xics_smp_probe() */
    .probe      = xics_smp_probe,
    .kick_cpu   = smp_pSeries_kick_cpu,
    .setup_cpu  = smp_xics_setup_cpu,
    .cpu_bootable   = smp_pSeries_cpu_bootable,
};

/* This is called very early */
static void __init smp_init_pseries(void)
{
    int i;

    pr_debug(" -> smp_init_pSeries()\n");

    alloc_bootmem_cpumask_var(&of_spin_mask);

    /* Mark threads which are still spinning in hold loops. */
    if (cpu_has_feature(CPU_FTR_SMT)) {
        for_each_present_cpu(i) { 
            if (cpu_thread_in_core(i) == 0)
                cpumask_set_cpu(i, of_spin_mask);
        }
    } else {
        cpumask_copy(of_spin_mask, cpu_present_mask);
    }

    cpumask_clear_cpu(boot_cpuid, of_spin_mask);

    /* Non-lpar has additional take/give timebase */
    if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
        smp_ops->give_timebase = rtas_give_timebase;
        smp_ops->take_timebase = rtas_take_timebase;
    }

    pr_debug(" <- smp_init_pSeries()\n");
}

void __init smp_init_pseries_mpic(void)
{
    smp_ops = &pSeries_mpic_smp_ops;

    smp_init_pseries();
}

void __init smp_init_pseries_xics(void)
{
    smp_ops = &pSeries_xics_smp_ops;

    smp_init_pseries();
}