blob: 869c22e5756145613d98a532425cc78538843bca [file] [log] [blame]
* Copyright 2010 Tilera Corporation. All Rights Reserved.
* 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, version 2.
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
#include <linux/sched/task.h>
#include <linux/kernel_stat.h>
#include <linux/bootmem.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/percpu.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/irq.h>
#include <asm/mmu_context.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
/* State of each CPU. */
static DEFINE_PER_CPU(int, cpu_state) = { 0 };
/* The messaging code jumps to this pointer during boot-up */
unsigned long start_cpu_function_addr;
/* Called very early during startup to mark boot cpu as online */
void __init smp_prepare_boot_cpu(void)
int cpu = smp_processor_id();
set_cpu_online(cpu, 1);
set_cpu_present(cpu, 1);
__this_cpu_write(cpu_state, CPU_ONLINE);
static void start_secondary(void);
* Called at the top of init() to launch all the other CPUs.
* They run free to complete their initialization and then wait
* until they get an IPI from the boot cpu to come online.
void __init smp_prepare_cpus(unsigned int max_cpus)
long rc;
int cpu, cpu_count;
int boot_cpu = smp_processor_id();
current_thread_info()->cpu = boot_cpu;
* Pin this task to the boot CPU while we bring up the others,
* just to make sure we don't uselessly migrate as they come up.
rc = sched_setaffinity(current->pid, cpumask_of(boot_cpu));
if (rc != 0)
pr_err("Couldn't set init affinity to boot cpu (%ld)\n", rc);
/* Print information about disabled and dataplane cpus. */
* Tell the messaging subsystem how to respond to the
* startup message. We use a level of indirection to avoid
* confusing the linker with the fact that the messaging
* subsystem is calling __init code.
start_cpu_function_addr = (unsigned long) &online_secondary;
/* Set up thread context for all new processors. */
cpu_count = 1;
for (cpu = 0; cpu < NR_CPUS; ++cpu) {
struct task_struct *idle;
if (cpu == boot_cpu)
if (!cpu_possible(cpu)) {
* Make this processor do nothing on boot.
* Note that we don't give the boot_pc function
* a stack, so it has to be assembly code.
per_cpu(boot_sp, cpu) = 0;
per_cpu(boot_pc, cpu) = (unsigned long) smp_nap;
/* Create a new idle thread to run start_secondary() */
idle = fork_idle(cpu);
if (IS_ERR(idle))
panic("failed fork for CPU %d", cpu);
idle->thread.pc = (unsigned long) start_secondary;
/* Make this thread the boot thread for this processor */
per_cpu(boot_sp, cpu) = task_ksp0(idle);
per_cpu(boot_pc, cpu) = idle->thread.pc;
BUG_ON(cpu_count > (max_cpus ? max_cpus : 1));
/* Fire up the other tiles, if any */
if (cpumask_weight(cpu_present_mask) > 1) {
mb(); /* make sure all data is visible to new processors */
static __initdata struct cpumask init_affinity;
static __init int reset_init_affinity(void)
long rc = sched_setaffinity(current->pid, &init_affinity);
if (rc != 0)
pr_warn("couldn't reset init affinity (%ld)\n", rc);
return 0;
static struct cpumask cpu_started;
* Activate a secondary processor. Very minimal; don't add anything
* to this path without knowing what you're doing, since SMP booting
* is pretty fragile.
static void start_secondary(void)
int cpuid;
cpuid = smp_processor_id();
/* Set our thread pointer appropriately. */
* In large machines even this will slow us down, since we
* will be contending for for the printk spinlock.
/* printk(KERN_DEBUG "Initializing CPU#%d\n", cpuid); */
/* Initialize the current asid for our first page table. */
__this_cpu_write(current_asid, min_asid);
/* Set up this thread as another owner of the init_mm */
current->active_mm = &init_mm;
if (current->mm)
enter_lazy_tlb(&init_mm, current);
/* Allow hypervisor messages to be received */
/* Indicate that we're ready to come up. */
/* Must not do this before we're ready to receive messages */
if (cpumask_test_and_set_cpu(cpuid, &cpu_started)) {
pr_warn("CPU#%d already started!\n", cpuid);
for (;;)
* Bring a secondary processor online.
void online_secondary(void)
* low-memory mappings have been cleared, flush them from
* the local TLBs too.
/* This must be done before setting cpu_online_mask */
set_cpu_online(smp_processor_id(), 1);
__this_cpu_write(cpu_state, CPU_ONLINE);
/* Set up tile-specific state for this cpu. */
/* Set up tile-timer clock-event device on this cpu */
int __cpu_up(unsigned int cpu, struct task_struct *tidle)
/* Wait 5s total for all CPUs for them to come online */
static int timeout;
for (; !cpumask_test_cpu(cpu, &cpu_started); timeout++) {
if (timeout >= 50000) {
pr_info("skipping unresponsive cpu%d\n", cpu);
return -EIO;
per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
/* Unleash the CPU! */
send_IPI_single(cpu, MSG_TAG_START_CPU);
while (!cpumask_test_cpu(cpu, cpu_online_mask))
return 0;
static void panic_start_cpu(void)
panic("Received a MSG_START_CPU IPI after boot finished.");
void __init smp_cpus_done(unsigned int max_cpus)
int cpu, next, rc;
/* Reset the response to a (now illegal) MSG_START_CPU IPI. */
start_cpu_function_addr = (unsigned long) &panic_start_cpu;
cpumask_copy(&init_affinity, cpu_online_mask);
* Pin ourselves to a single cpu in the initial affinity set
* so that kernel mappings for the rootfs are not in the dataplane,
* if set, and to avoid unnecessary migrating during bringup.
* Use the last cpu just in case the whole chip has been
* isolated from the scheduler, to keep init away from likely
* more useful user code. This also ensures that work scheduled
* via schedule_delayed_work() in the init routines will land
* on this cpu.
for (cpu = cpumask_first(&init_affinity);
(next = cpumask_next(cpu, &init_affinity)) < nr_cpu_ids;
cpu = next)
rc = sched_setaffinity(current->pid, cpumask_of(cpu));
if (rc != 0)
pr_err("Couldn't set init affinity to cpu %d (%d)\n", cpu, rc);