* published by the Free Software Foundation.
*/
+#include <linux/atomic.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/clockchips.h>
#include <linux/hrtimer.h>
#include <linux/tick.h>
+#include <linux/notifier.h>
#include <linux/mm.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/irqchip/arm-gic.h>
}
struct bL_thread {
+ spinlock_t lock;
struct task_struct *task;
wait_queue_head_t wq;
int wanted_cluster;
struct completion started;
+ bL_switch_completion_handler completer;
+ void *completer_cookie;
};
static struct bL_thread bL_threads[NR_CPUS];
struct bL_thread *t = arg;
struct sched_param param = { .sched_priority = 1 };
int cluster;
+ bL_switch_completion_handler completer;
+ void *completer_cookie;
sched_setscheduler_nocheck(current, SCHED_FIFO, ¶m);
complete(&t->started);
wait_event_interruptible(t->wq,
t->wanted_cluster != -1 ||
kthread_should_stop());
- cluster = xchg(&t->wanted_cluster, -1);
- if (cluster != -1)
+
+ spin_lock(&t->lock);
+ cluster = t->wanted_cluster;
+ completer = t->completer;
+ completer_cookie = t->completer_cookie;
+ t->wanted_cluster = -1;
+ t->completer = NULL;
+ spin_unlock(&t->lock);
+
+ if (cluster != -1) {
bL_switch_to(cluster);
+
+ if (completer)
+ completer(completer_cookie);
+ }
} while (!kthread_should_stop());
return 0;
}
/*
- * bL_switch_request - Switch to a specific cluster for the given CPU
+ * bL_switch_request_cb - Switch to a specific cluster for the given CPU,
+ * with completion notification via a callback
*
* @cpu: the CPU to switch
* @new_cluster_id: the ID of the cluster to switch to.
+ * @completer: switch completion callback. if non-NULL,
+ * @completer(@completer_cookie) will be called on completion of
+ * the switch, in non-atomic context.
+ * @completer_cookie: opaque context argument for @completer.
*
* This function causes a cluster switch on the given CPU by waking up
* the appropriate switcher thread. This function may or may not return
* before the switch has occurred.
+ *
+ * If a @completer callback function is supplied, it will be called when
+ * the switch is complete. This can be used to determine asynchronously
+ * when the switch is complete, regardless of when bL_switch_request()
+ * returns. When @completer is supplied, no new switch request is permitted
+ * for the affected CPU until after the switch is complete, and @completer
+ * has returned.
*/
-int bL_switch_request(unsigned int cpu, unsigned int new_cluster_id)
+int bL_switch_request_cb(unsigned int cpu, unsigned int new_cluster_id,
+ bL_switch_completion_handler completer,
+ void *completer_cookie)
{
struct bL_thread *t;
}
t = &bL_threads[cpu];
+
if (IS_ERR(t->task))
return PTR_ERR(t->task);
if (!t->task)
return -ESRCH;
+ spin_lock(&t->lock);
+ if (t->completer) {
+ spin_unlock(&t->lock);
+ return -EBUSY;
+ }
+ t->completer = completer;
+ t->completer_cookie = completer_cookie;
t->wanted_cluster = new_cluster_id;
+ spin_unlock(&t->lock);
wake_up(&t->wq);
return 0;
}
-EXPORT_SYMBOL_GPL(bL_switch_request);
+EXPORT_SYMBOL_GPL(bL_switch_request_cb);
/*
* Activation and configuration code.
*/
+static DEFINE_MUTEX(bL_switcher_activation_lock);
+static BLOCKING_NOTIFIER_HEAD(bL_activation_notifier);
static unsigned int bL_switcher_active;
static unsigned int bL_switcher_cpu_original_cluster[NR_CPUS];
static cpumask_t bL_switcher_removed_logical_cpus;
+int bL_switcher_register_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_register(&bL_activation_notifier, nb);
+}
+EXPORT_SYMBOL_GPL(bL_switcher_register_notifier);
+
+int bL_switcher_unregister_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_unregister(&bL_activation_notifier, nb);
+}
+EXPORT_SYMBOL_GPL(bL_switcher_unregister_notifier);
+
+static int bL_activation_notify(unsigned long val)
+{
+ int ret;
+
+ ret = blocking_notifier_call_chain(&bL_activation_notifier, val, NULL);
+ if (ret & NOTIFY_STOP_MASK)
+ pr_err("%s: notifier chain failed with status 0x%x\n",
+ __func__, ret);
+ return notifier_to_errno(ret);
+}
+
static void bL_switcher_restore_cpus(void)
{
int i;
{
int cpu, ret;
+ mutex_lock(&bL_switcher_activation_lock);
cpu_hotplug_driver_lock();
if (bL_switcher_active) {
cpu_hotplug_driver_unlock();
+ mutex_unlock(&bL_switcher_activation_lock);
return 0;
}
pr_info("big.LITTLE switcher initializing\n");
+ ret = bL_activation_notify(BL_NOTIFY_PRE_ENABLE);
+ if (ret)
+ goto error;
+
ret = bL_switcher_halve_cpus();
- if (ret) {
- cpu_hotplug_driver_unlock();
- return ret;
- }
+ if (ret)
+ goto error;
for_each_online_cpu(cpu) {
struct bL_thread *t = &bL_threads[cpu];
+ spin_lock_init(&t->lock);
init_waitqueue_head(&t->wq);
init_completion(&t->started);
t->wanted_cluster = -1;
}
bL_switcher_active = 1;
- cpu_hotplug_driver_unlock();
-
+ bL_activation_notify(BL_NOTIFY_POST_ENABLE);
pr_info("big.LITTLE switcher initialized\n");
- return 0;
+ goto out;
+
+error:
+ pr_warn("big.LITTLE switcher initialization failed\n");
+ bL_activation_notify(BL_NOTIFY_POST_DISABLE);
+
+out:
+ cpu_hotplug_driver_unlock();
+ mutex_unlock(&bL_switcher_activation_lock);
+ return ret;
}
#ifdef CONFIG_SYSFS
struct bL_thread *t;
struct task_struct *task;
+ mutex_lock(&bL_switcher_activation_lock);
cpu_hotplug_driver_lock();
- if (!bL_switcher_active) {
- cpu_hotplug_driver_unlock();
- return;
+
+ if (!bL_switcher_active)
+ goto out;
+
+ if (bL_activation_notify(BL_NOTIFY_PRE_DISABLE) != 0) {
+ bL_activation_notify(BL_NOTIFY_POST_ENABLE);
+ goto out;
}
+
bL_switcher_active = 0;
/*
}
bL_switcher_restore_cpus();
+ bL_activation_notify(BL_NOTIFY_POST_DISABLE);
+
+out:
cpu_hotplug_driver_unlock();
+ mutex_unlock(&bL_switcher_activation_lock);
}
static ssize_t bL_switcher_active_show(struct kobject *kobj,
#endif /* CONFIG_SYSFS */
+bool bL_switcher_get_enabled(void)
+{
+ mutex_lock(&bL_switcher_activation_lock);
+
+ return bL_switcher_active;
+}
+EXPORT_SYMBOL_GPL(bL_switcher_get_enabled);
+
+void bL_switcher_put_enabled(void)
+{
+ mutex_unlock(&bL_switcher_activation_lock);
+}
+EXPORT_SYMBOL_GPL(bL_switcher_put_enabled);
+
/*
* Veto any CPU hotplug operation on those CPUs we've removed
* while the switcher is active.
projects / karo-tx-linux.git / blobdiff