diff options
Diffstat (limited to 'arch/arm/common')
| -rw-r--r-- | arch/arm/common/bL_switcher.c | 53 |
1 files changed, 48 insertions, 5 deletions
diff --git a/arch/arm/common/bL_switcher.c b/arch/arm/common/bL_switcher.c index 016488730cb..34316be404d 100644 --- a/arch/arm/common/bL_switcher.c +++ b/arch/arm/common/bL_switcher.c @@ -9,6 +9,7 @@ * published by the Free Software Foundation. */ +#include <linux/atomic.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> @@ -25,6 +26,7 @@ #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> @@ -224,10 +226,13 @@ static int bL_switch_to(unsigned int new_cluster_id) } 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]; @@ -237,6 +242,8 @@ static int bL_switcher_thread(void *arg) 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); @@ -247,9 +254,21 @@ static int bL_switcher_thread(void *arg) 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; @@ -270,16 +289,30 @@ static struct task_struct *bL_switcher_thread_create(int cpu, void *arg) } /* - * 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; @@ -289,16 +322,25 @@ int bL_switch_request(unsigned int cpu, unsigned int new_cluster_id) } 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. @@ -460,6 +502,7 @@ static int bL_switcher_enable(void) 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; |