/*
* SMP initialisation and IPI support
* Based on arch/arm/kernel/smp.c
*
* Copyright (C) 2012 ARM Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/cache.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/seq_file.h>
#include <linux/irq.h>
#include <linux/percpu.h>
#include <linux/clockchips.h>
#include <linux/completion.h>
#include <linux/of.h>
#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/cputype.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/smp_plat.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>
/*
* as from 2.5, kernels no longer have an init_tasks structure
* so we need some other way of telling a new secondary core
* where to place its SVC stack
*/
struct secondary_data secondary_data;
volatile unsigned long secondary_holding_pen_release = INVALID_HWID;
enum ipi_msg_type {
IPI_RESCHEDULE,
IPI_CALL_FUNC,
IPI_CALL_FUNC_SINGLE,
IPI_CPU_STOP,
};
static DEFINE_RAW_SPINLOCK(boot_lock);
/*
* Write secondary_holding_pen_release in a way that is guaranteed to be
* visible to all observers, irrespective of whether they're taking part
* in coherency or not. This is necessary for the hotplug code to work
* reliably.
*/
static void __cpuinit write_pen_release(u64 val)
{
void *start = (void *)&secondary_holding_pen_release;
unsigned long size = sizeof(secondary_holding_pen_release);
secondary_holding_pen_release = val;
__flush_dcache_area(start, size);
}
/*
* Boot a secondary CPU, and assign it the specified idle task.
* This also gives us the initial stack to use for this CPU.
*/
static int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
{
unsigned long timeout;
/*
* Set synchronisation state between this boot processor
* and the secondary one
*/
raw_spin_lock(&boot_lock);
/*
* Update the pen release flag.
*/
write_pen_release(cpu_logical_map(cpu));
/*
* Send an event, causing the secondaries to read pen_release.
*/
sev();
timeout = jiffies + (1 * HZ);
while (time_before(jiffies, timeout)) {
if (secondary_holding_pen_release == INVALID_HWID)
break;
udelay(10);
}
/*
* Now the secondary core is starting up let it run its
* calibrations, then wait for it to finish
*/
raw_spin_unlock(&boot_lock);
return secondary_holding_pen_release != INVALID_HWID ? -ENOSYS : 0;
}
static DECLARE_COMPLETION(cpu_running);
int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle)
{
int ret;
/*
* We need to tell the secondary core where to find its stack and the
* page tables.
*/
secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
__flush_dcache_area(&secondary_data, sizeof(secondary_data));
/*
* Now bring the CPU into our world.
*/
ret = boot_secondary(cpu, idle);
if (ret == 0) {
/*
* CPU was successfully started, wait for it to come online or
* time out.
*/
wait_for_completion_timeout(&cpu_running,
msecs_to_jiffies(1000));
if (!cpu_online(cpu)) {
pr_crit("CPU%u: failed to come online\n", cpu);
ret = -EIO;
}
} else {
pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
}
secondary_data.stack = NULL;
return ret;
}
/*
* This is the secondary CPU boot entry. We're using this CPUs
* idle thread stack, but a set of temporary page tables.
*/
asmlinkage void __cpuinit secondary_start_kernel(void)
{
struct mm_struct *mm = &init_mm;
unsigned int cpu = smp_processor_id();
printk("CPU%u: Booted secondary processor\n", cpu);
/*
* All kernel threads share the same mm context; grab a
* reference and switch to it.
*/
atomic_inc(&mm->mm_count);
current->active_mm = mm;
cpumask_set_cpu(cpu, mm_cpumask(mm));
/*
* TTBR0 is only used for the identity mapping at this stage. Make it
* point to zero page to avoid speculatively fetching new entries.
*/
cpu_set_reserved_ttbr0();
flush_tlb_all();
preempt_disable();
trace_hardirqs_off();
/*
* Let the primary processor know we're out of the
* pen, then head off into the C entry point
*/
write_pen_release(INVALID_HWID);
/*
* Synchronise with the boot thread.
*/
raw_spin_lock(&boot_lock);
raw_spin_unlock(&boot_lock);
/*
* Enable local interrupts.
*/
notify_cpu_starting(cpu);
local_irq_enable();
local_fiq_enable();
/*
* OK, now it's safe to let the boot CPU continue. Wait for
* the CPU migration code to notice that the CPU is online
* before we continue.
*/
set_cpu_online(cpu, true);
complete(&cpu_running);
/*
* OK, it's off to the idle thread for us
*/
cpu_startup_entry(CPUHP_ONLINE);
}
void __init smp_cpus_done(unsigned int max_cpus)
{
unsigned long bogosum = loops_per_jiffy * num_online_cpus();
pr_info("SMP: Total of %d processors activated (%lu.%02lu BogoMIPS).\n",
num_online_cpus(), bogosum / (500000/HZ),
(bogosum / (5000/HZ)) % 100);
}
void __init smp_prepare_boot_cpu(void)
{
}
static void (*smp_cross_call)(const struct cpumask *, unsigned int);
static const struct smp_enable_ops *enable_ops[] __initconst = {
&smp_spin_table_ops,
&smp_psci_ops,
NULL,
};
static const struct smp_enable_ops *smp_enable_ops[NR_CPUS];
static const struct smp_enable_ops * __init smp_get_enable_ops(const char *name)
{
const struct smp_enable_ops **ops = enable_ops;
while (*ops) {
if (!strcmp(name, (*ops)->name))
return *ops;
ops++;
}
return NULL;
}
/*
* Enumerate the possible CPU set from the device tree and build the
* cpu logical map array containing MPIDR values related to logical
* cpus. Assumes that cpu_logical_map(0) has already been initialized.
*/
void __init smp_init_cpus(void)
{
const char *enable_method;
struct device_node *dn = NULL;
int i, cpu = 1;
bool bootcpu_valid = false;
while ((dn = of_find_node_by_type(dn, "cpu"))) {
const u32 *cell;
u64 hwid;
/*
* A cpu node with missing "reg" property is
* considered invalid to build a cpu_logical_map
* entry.
*/
cell = of_get_property(dn, "reg", NULL);
if (!cell) {
pr_err("%s: missing reg property\n", dn->full_name);
goto next;
}
hwid = of_read_number(cell, of_n_addr_cells(dn));
/*
* Non affinity bits must be set to 0 in the DT
*/
if (hwid & ~MPIDR_HWID_BITMASK) {
pr_err("%s: invalid reg property\n", dn->full_name);
goto next;
}
/*
* Duplicate MPIDRs are a recipe for disaster. Scan
* all initialized entries and check for
* duplicates. If any is found just ignore the cpu.
* cpu_logical_map was initialized to INVALID_HWID to
* avoid matching valid MPIDR values.
*/
for (i = 1; (i < cpu) && (i < NR_CPUS); i++) {
if (cpu_logical_map(i) == hwid) {
pr_err("%s: duplicate cpu reg properties in the DT\n",
dn->full_name);
goto next;
}
}
/*
* The numbering scheme requires that the boot CPU
* must be assigned logical id 0. Record it so that
* the logical map built from DT is validated and can
* be used.
*/
if (hwid == cpu_logical_map(0)) {
if (bootcpu_valid) {
pr_err("%s: duplicate boot cpu reg property in DT\n",
dn->full_name);
goto next;
}
bootcpu_valid = true;
/*
* cpu_logical_map has already been
* initialized and the boot cpu doesn't need
* the enable-method so continue without
* incrementing cpu.
*/
continue;
}
if (cpu >= NR_CPUS)
goto next;
/*
* We currently support only the "spin-table" enable-method.
*/
enable_method = of_get_property(dn, "enable-method", NULL);
if (!enable_method) {
pr_err("%s: missing enable-method property\n",
dn->full_name);
goto next;
}
smp_enable_ops[cpu] = smp_get_enable_ops(enable_method);
if (!smp_enable_ops[cpu]) {
pr_err("%s: invalid enable-method property: %s\n",
dn->full_name, enable_method);
goto next;
}
if (smp_enable_ops[cpu]->init_cpu(dn, cpu))
goto next;
pr_debug("cpu logical map 0x%llx\n", hwid);
cpu_logical_map(cpu) = hwid;
next:
cpu++;
}
/* sanity check */
if (cpu > NR_CPUS)
pr_warning("no. of cores (%d) greater than configured maximum of %d - clipping\n",
cpu, NR_CPUS);
if (!bootcpu_valid) {
pr_err("DT missing boot CPU MPIDR, not enabling secondaries\n");
return;
}
/*
* All the cpus that made it to the cpu_logical_map have been
* validated so set them as possible cpus.
*/
for (i = 0; i < NR_CPUS; i++)
if (cpu_logical_map(i) != INVALID_HWID)
set_cpu_possible(i, true);
}
void __init smp_prepare_cpus(unsigned int max_cpus)
{
int cpu, err;
unsigned int ncores = num_possible_cpus();
/*
* are we trying to boot more cores than exist?
*/
if (max_cpus > ncores)
max_cpus = ncores;
/* Don't bother if we're effectively UP */
if (max_cpus <= 1)
return;
/*
* Initialise the present map (which describes the set of CPUs
* actually populated at the present time) and release the
* secondaries from the bootloader.
*
* Make sure we online at most (max_cpus - 1) additional CPUs.
*/
max_cpus--;
for_each_possible_cpu(cpu) {
if (max_cpus == 0)
break;
if (cpu == smp_processor_id())
continue;
if (!smp_enable_ops[cpu])
continue;
err = smp_enable_ops[cpu]->prepare_cpu(cpu);
if (err)
continue;
set_cpu_present(cpu, true);
max_cpus--;
}
}
void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
{
smp_cross_call = fn;
}
void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
smp_cross_call(mask, IPI_CALL_FUNC);
}
void arch_send_call_function_single_ipi(int cpu)
{
smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
}
static const char *ipi_types[NR_IPI] = {
#define S(x,s) [x - IPI_RESCHEDULE] = s
S(IPI_RESCHEDULE, "Rescheduling interrupts"),
S(IPI_CALL_FUNC, "Function call interrupts"),
S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
S(IPI_CPU_STOP, "CPU stop interrupts"),
};
void show_ipi_list(struct seq_file *p, int prec)
{
unsigned int cpu, i;
for (i = 0; i < NR_IPI; i++) {
seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i + IPI_RESCHEDULE,
prec >= 4 ? " " : "");
for_each_present_cpu(cpu)
seq_printf(p, "%10u ",
__get_irq_stat(cpu, ipi_irqs[i]));
seq_printf(p, " %s\n", ipi_types[i]);
}
}
u64 smp_irq_stat_cpu(unsigned int cpu)
{
u64 sum = 0;
int i;
for (i = 0; i < NR_IPI; i++)
sum += __get_irq_stat(cpu, ipi_irqs[i]);
return sum;
}
static DEFINE_RAW_SPINLOCK(stop_lock);
/*
* ipi_cpu_stop - handle IPI from smp_send_stop()
*/
static void ipi_cpu_stop(unsigned int cpu)
{
if (system_state == SYSTEM_BOOTING ||
system_state == SYSTEM_RUNNING) {
raw_spin_lock(&stop_lock);
pr_crit("CPU%u: stopping\n", cpu);
dump_stack();
raw_spin_unlock(&stop_lock);
}
set_cpu_online(cpu, false);
local_fiq_disable();
local_irq_disable();
while (1)
cpu_relax();
}
/*
* Main handler for inter-processor interrupts
*/
void handle_IPI(int ipinr, struct pt_regs *regs)
{
unsigned int cpu = smp_processor_id();
struct pt_regs *old_regs = set_irq_regs(regs);
if (ipinr >= IPI_RESCHEDULE && ipinr < IPI_RESCHEDULE + NR_IPI)
__inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_RESCHEDULE]);
switch (ipinr) {
case IPI_RESCHEDULE:
scheduler_ipi();
break;
case IPI_CALL_FUNC:
irq_enter();
generic_smp_call_function_interrupt();
irq_exit();
break;
case IPI_CALL_FUNC_SINGLE:
irq_enter();
generic_smp_call_function_single_interrupt();
irq_exit();
break;
case IPI_CPU_STOP:
irq_enter();
ipi_cpu_stop(cpu);
irq_exit();
break;
default:
pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
break;
}
set_irq_regs(old_regs);
}
void smp_send_reschedule(int cpu)
{
smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
}
void smp_send_stop(void)
{
unsigned long timeout;
if (num_online_cpus() > 1) {
cpumask_t mask;
cpumask_copy(&mask, cpu_online_mask);
cpu_clear(smp_processor_id(), mask);
smp_cross_call(&mask, IPI_CPU_STOP);
}
/* Wait up to one second for other CPUs to stop */
timeout = USEC_PER_SEC;
while (num_online_cpus() > 1 && timeout--)
udelay(1);
if (num_online_cpus() > 1)
pr_warning("SMP: failed to stop secondary CPUs\n");
}
/*
* not supported here
*/
int setup_profiling_timer(unsigned int multiplier)
{
return -EINVAL;
}
