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/*
* SMP support for PowerNV machines.
*
* Copyright 2011 IBM Corp.
*
* 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/module.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/cpu.h>
#include <asm/irq.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/vdso_datapage.h>
#include <asm/cputhreads.h>
#include <asm/xics.h>
#include <asm/opal.h>
#include "powernv.h"
#ifdef DEBUG
#include <asm/udbg.h>
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif
static void pnv_smp_setup_cpu(int cpu)
{
if (cpu != boot_cpuid)
xics_setup_cpu();
}
static int pnv_smp_cpu_bootable(unsigned int nr)
{
/* Special case - we inhibit secondary thread startup
* during boot if the user requests it.
*/
if (system_state == SYSTEM_BOOTING && 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;
}
int pnv_smp_kick_cpu(int nr)
{
unsigned int pcpu = get_hard_smp_processor_id(nr);
unsigned long start_here = __pa(*((unsigned long *)
generic_secondary_smp_init));
long rc;
BUG_ON(nr < 0 || nr >= NR_CPUS);
/*
* If we already started or OPALv2 is not supported, we just
* kick the CPU via the PACA
*/
if (paca[nr].cpu_start || !firmware_has_feature(FW_FEATURE_OPALv2))
goto kick;
/*
* At this point, the CPU can either be spinning on the way in
* from kexec or be inside OPAL waiting to be started for the
* first time. OPAL v3 allows us to query OPAL to know if it
* has the CPUs, so we do that
*/
if (firmware_has_feature(FW_FEATURE_OPALv3)) {
uint8_t status;
rc = opal_query_cpu_status(pcpu, &status);
if (rc != OPAL_SUCCESS) {
pr_warn("OPAL Error %ld querying CPU %d state\n",
rc, nr);
return -ENODEV;
}
/*
* Already started, just kick it, probably coming from
* kexec and spinning
*/
if (status == OPAL_THREAD_STARTED)
goto kick;
/*
* Available/inactive, let's kick it
*/
if (status == OPAL_THREAD_INACTIVE) {
pr_devel("OPAL: Starting CPU %d (HW 0x%x)...\n",
nr, pcpu);
rc = opal_start_cpu(pcpu, start_here);
if (rc != OPAL_SUCCESS) {
pr_warn("OPAL Error %ld starting CPU %d\n",
rc, nr);
return -ENODEV;
}
} else {
/*
* An unavailable CPU (or any other unknown status)
* shouldn't be started. It should also
* not be in the possible map but currently it can
* happen
*/
pr_devel("OPAL: CPU %d (HW 0x%x) is unavailable"
" (status %d)...\n", nr, pcpu, status);
return -ENODEV;
}
} else {
/*
* On OPAL v2, we just kick it and hope for the best,
* we must not test the error from opal_start_cpu() or
* we would fail to get CPUs from kexec.
*/
opal_start_cpu(pcpu, start_here);
}
kick:
return smp_generic_kick_cpu(nr);
}
#ifdef CONFIG_HOTPLUG_CPU
static int pnv_smp_cpu_disable(void)
{
int cpu = smp_processor_id();
/* This is identical to pSeries... might consolidate by
* moving migrate_irqs_away to a ppc_md with default to
* the generic fixup_irqs. --BenH.
*/
set_cpu_online(cpu, false);
vdso_data->processorCount--;
if (cpu == boot_cpuid)
boot_cpuid = cpumask_any(cpu_online_mask);
xics_migrate_irqs_away();
return 0;
}
static void pnv_smp_cpu_kill_self(void)
{
unsigned int cpu;
/* Standard hot unplug procedure */
local_irq_disable();
idle_task_exit();
current->active_mm = NULL; /* for sanity */
cpu = smp_processor_id();
DBG("CPU%d offline\n", cpu);
generic_set_cpu_dead(cpu);
smp_wmb();
/* We don't want to take decrementer interrupts while we are offline,
* so clear LPCR:PECE1. We keep PECE2 enabled.
*/
mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
while (!generic_check_cpu_restart(cpu)) {
power7_nap();
if (!generic_check_cpu_restart(cpu)) {
DBG("CPU%d Unexpected exit while offline !\n", cpu);
/* We may be getting an IPI, so we re-enable
* interrupts to process it, it will be ignored
* since we aren't online (hopefully)
*/
local_irq_enable();
local_irq_disable();
}
}
mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
DBG("CPU%d coming online...\n", cpu);
}
#endif /* CONFIG_HOTPLUG_CPU */
static struct smp_ops_t pnv_smp_ops = {
.message_pass = smp_muxed_ipi_message_pass,
.cause_ipi = NULL, /* Filled at runtime by xics_smp_probe() */
.probe = xics_smp_probe,
.kick_cpu = pnv_smp_kick_cpu,
.setup_cpu = pnv_smp_setup_cpu,
.cpu_bootable = pnv_smp_cpu_bootable,
#ifdef CONFIG_HOTPLUG_CPU
.cpu_disable = pnv_smp_cpu_disable,
.cpu_die = generic_cpu_die,
#endif /* CONFIG_HOTPLUG_CPU */
};
/* This is called very early during platform setup_arch */
void __init pnv_smp_init(void)
{
smp_ops = &pnv_smp_ops;
/* XXX We don't yet have a proper entry point from HAL, for
* now we rely on kexec-style entry from BML
*/
#ifdef CONFIG_PPC_RTAS
/* 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;
}
#endif /* CONFIG_PPC_RTAS */
#ifdef CONFIG_HOTPLUG_CPU
ppc_md.cpu_die = pnv_smp_cpu_kill_self;
#endif
}
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