ARM: bL_switcher: ability to enable and disable the switcher via sysfs
The /sys/kernel/bL_switcher/enable file allows to enable or disable the switcher by writing 1 or 0 to it respectively. It is still enabled by default on boot. Signed-off-by: Nicolas Pitre <nico@linaro.org>
This commit is contained in:
Nicolas Pitre
parent
ed96762e32
commit
6b7437aed1
|
|
@ -24,6 +24,7 @@
|
|||
#include <linux/tick.h>
|
||||
#include <linux/mm.h>
|
||||
#include <linux/string.h>
|
||||
#include <linux/sysfs.h>
|
||||
#include <linux/irqchip/arm-gic.h>
|
||||
|
||||
#include <asm/smp_plat.h>
|
||||
|
|
@ -220,6 +221,7 @@ struct bL_thread {
|
|||
struct task_struct *task;
|
||||
wait_queue_head_t wq;
|
||||
int wanted_cluster;
|
||||
struct completion started;
|
||||
};
|
||||
|
||||
static struct bL_thread bL_threads[NR_CPUS];
|
||||
|
|
@ -231,6 +233,7 @@ static int bL_switcher_thread(void *arg)
|
|||
int cluster;
|
||||
|
||||
sched_setscheduler_nocheck(current, SCHED_FIFO, ¶m);
|
||||
complete(&t->started);
|
||||
|
||||
do {
|
||||
if (signal_pending(current))
|
||||
|
|
@ -246,7 +249,7 @@ static int bL_switcher_thread(void *arg)
|
|||
return 0;
|
||||
}
|
||||
|
||||
static struct task_struct * __init bL_switcher_thread_create(int cpu, void *arg)
|
||||
static struct task_struct *bL_switcher_thread_create(int cpu, void *arg)
|
||||
{
|
||||
struct task_struct *task;
|
||||
|
||||
|
|
@ -295,9 +298,11 @@ EXPORT_SYMBOL_GPL(bL_switch_request);
|
|||
* Activation and configuration code.
|
||||
*/
|
||||
|
||||
static unsigned int bL_switcher_active;
|
||||
static unsigned int bL_switcher_cpu_original_cluster[MAX_CPUS_PER_CLUSTER];
|
||||
static cpumask_t bL_switcher_removed_logical_cpus;
|
||||
|
||||
static void __init bL_switcher_restore_cpus(void)
|
||||
static void bL_switcher_restore_cpus(void)
|
||||
{
|
||||
int i;
|
||||
|
||||
|
|
@ -305,7 +310,7 @@ static void __init bL_switcher_restore_cpus(void)
|
|||
cpu_up(i);
|
||||
}
|
||||
|
||||
static int __init bL_switcher_halve_cpus(void)
|
||||
static int bL_switcher_halve_cpus(void)
|
||||
{
|
||||
int cpu, cluster, i, ret;
|
||||
cpumask_t cluster_mask[2], common_mask;
|
||||
|
|
@ -349,8 +354,10 @@ static int __init bL_switcher_halve_cpus(void)
|
|||
* is equal to their physical CPU number. This is
|
||||
* not perfect but good enough for now.
|
||||
*/
|
||||
if (cpu == i)
|
||||
if (cpu == i) {
|
||||
bL_switcher_cpu_original_cluster[cpu] = cluster;
|
||||
continue;
|
||||
}
|
||||
}
|
||||
|
||||
ret = cpu_down(i);
|
||||
|
|
@ -364,18 +371,18 @@ static int __init bL_switcher_halve_cpus(void)
|
|||
return 0;
|
||||
}
|
||||
|
||||
static int __init bL_switcher_init(void)
|
||||
static int bL_switcher_enable(void)
|
||||
{
|
||||
int cpu, ret;
|
||||
|
||||
pr_info("big.LITTLE switcher initializing\n");
|
||||
|
||||
if (MAX_NR_CLUSTERS != 2) {
|
||||
pr_err("%s: only dual cluster systems are supported\n", __func__);
|
||||
return -EINVAL;
|
||||
cpu_hotplug_driver_lock();
|
||||
if (bL_switcher_active) {
|
||||
cpu_hotplug_driver_unlock();
|
||||
return 0;
|
||||
}
|
||||
|
||||
cpu_hotplug_driver_lock();
|
||||
pr_info("big.LITTLE switcher initializing\n");
|
||||
|
||||
ret = bL_switcher_halve_cpus();
|
||||
if (ret) {
|
||||
cpu_hotplug_driver_unlock();
|
||||
|
|
@ -385,13 +392,155 @@ static int __init bL_switcher_init(void)
|
|||
for_each_online_cpu(cpu) {
|
||||
struct bL_thread *t = &bL_threads[cpu];
|
||||
init_waitqueue_head(&t->wq);
|
||||
init_completion(&t->started);
|
||||
t->wanted_cluster = -1;
|
||||
t->task = bL_switcher_thread_create(cpu, t);
|
||||
}
|
||||
|
||||
bL_switcher_active = 1;
|
||||
cpu_hotplug_driver_unlock();
|
||||
|
||||
pr_info("big.LITTLE switcher initialized\n");
|
||||
return 0;
|
||||
}
|
||||
|
||||
#ifdef CONFIG_SYSFS
|
||||
|
||||
static void bL_switcher_disable(void)
|
||||
{
|
||||
unsigned int cpu, cluster, i;
|
||||
struct bL_thread *t;
|
||||
struct task_struct *task;
|
||||
|
||||
cpu_hotplug_driver_lock();
|
||||
if (!bL_switcher_active) {
|
||||
cpu_hotplug_driver_unlock();
|
||||
return;
|
||||
}
|
||||
bL_switcher_active = 0;
|
||||
|
||||
/*
|
||||
* To deactivate the switcher, we must shut down the switcher
|
||||
* threads to prevent any other requests from being accepted.
|
||||
* Then, if the final cluster for given logical CPU is not the
|
||||
* same as the original one, we'll recreate a switcher thread
|
||||
* just for the purpose of switching the CPU back without any
|
||||
* possibility for interference from external requests.
|
||||
*/
|
||||
for_each_online_cpu(cpu) {
|
||||
BUG_ON(cpu != (cpu_logical_map(cpu) & 0xff));
|
||||
t = &bL_threads[cpu];
|
||||
task = t->task;
|
||||
t->task = NULL;
|
||||
if (!task || IS_ERR(task))
|
||||
continue;
|
||||
kthread_stop(task);
|
||||
/* no more switch may happen on this CPU at this point */
|
||||
cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1);
|
||||
if (cluster == bL_switcher_cpu_original_cluster[cpu])
|
||||
continue;
|
||||
init_completion(&t->started);
|
||||
t->wanted_cluster = bL_switcher_cpu_original_cluster[cpu];
|
||||
task = bL_switcher_thread_create(cpu, t);
|
||||
if (!IS_ERR(task)) {
|
||||
wait_for_completion(&t->started);
|
||||
kthread_stop(task);
|
||||
cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1);
|
||||
if (cluster == bL_switcher_cpu_original_cluster[cpu])
|
||||
continue;
|
||||
}
|
||||
/* If execution gets here, we're in trouble. */
|
||||
pr_crit("%s: unable to restore original cluster for CPU %d\n",
|
||||
__func__, cpu);
|
||||
for_each_cpu(i, &bL_switcher_removed_logical_cpus) {
|
||||
if ((cpu_logical_map(i) & 0xff) != cpu)
|
||||
continue;
|
||||
pr_crit("%s: CPU %d can't be restored\n",
|
||||
__func__, i);
|
||||
cpumask_clear_cpu(i, &bL_switcher_removed_logical_cpus);
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
bL_switcher_restore_cpus();
|
||||
cpu_hotplug_driver_unlock();
|
||||
}
|
||||
|
||||
static ssize_t bL_switcher_active_show(struct kobject *kobj,
|
||||
struct kobj_attribute *attr, char *buf)
|
||||
{
|
||||
return sprintf(buf, "%u\n", bL_switcher_active);
|
||||
}
|
||||
|
||||
static ssize_t bL_switcher_active_store(struct kobject *kobj,
|
||||
struct kobj_attribute *attr, const char *buf, size_t count)
|
||||
{
|
||||
int ret;
|
||||
|
||||
switch (buf[0]) {
|
||||
case '0':
|
||||
bL_switcher_disable();
|
||||
ret = 0;
|
||||
break;
|
||||
case '1':
|
||||
ret = bL_switcher_enable();
|
||||
break;
|
||||
default:
|
||||
ret = -EINVAL;
|
||||
}
|
||||
|
||||
return (ret >= 0) ? count : ret;
|
||||
}
|
||||
|
||||
static struct kobj_attribute bL_switcher_active_attr =
|
||||
__ATTR(active, 0644, bL_switcher_active_show, bL_switcher_active_store);
|
||||
|
||||
static struct attribute *bL_switcher_attrs[] = {
|
||||
&bL_switcher_active_attr.attr,
|
||||
NULL,
|
||||
};
|
||||
|
||||
static struct attribute_group bL_switcher_attr_group = {
|
||||
.attrs = bL_switcher_attrs,
|
||||
};
|
||||
|
||||
static struct kobject *bL_switcher_kobj;
|
||||
|
||||
static int __init bL_switcher_sysfs_init(void)
|
||||
{
|
||||
int ret;
|
||||
|
||||
bL_switcher_kobj = kobject_create_and_add("bL_switcher", kernel_kobj);
|
||||
if (!bL_switcher_kobj)
|
||||
return -ENOMEM;
|
||||
ret = sysfs_create_group(bL_switcher_kobj, &bL_switcher_attr_group);
|
||||
if (ret)
|
||||
kobject_put(bL_switcher_kobj);
|
||||
return ret;
|
||||
}
|
||||
|
||||
#endif /* CONFIG_SYSFS */
|
||||
|
||||
static int __init bL_switcher_init(void)
|
||||
{
|
||||
int ret;
|
||||
|
||||
if (MAX_NR_CLUSTERS != 2) {
|
||||
pr_err("%s: only dual cluster systems are supported\n", __func__);
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
ret = bL_switcher_enable();
|
||||
if (ret)
|
||||
return ret;
|
||||
|
||||
#ifdef CONFIG_SYSFS
|
||||
ret = bL_switcher_sysfs_init();
|
||||
if (ret)
|
||||
pr_err("%s: unable to create sysfs entry\n", __func__);
|
||||
#endif
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
late_initcall(bL_switcher_init);
|
||||
|
|
|
|||
Loading…
Reference in a new issue