schedule: add scheduler_init_context()

Add an optional method that allow the schedule.h user to get
access to the thread context that will be used for scheduling.
This is critical when the callbacks are run in user-space context
and schedule.h client needs to grant access to objects like locks
to the callback thread.

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Author: kv2019i

src/include/sof/schedule/schedule.h

@@ -158,6 +158,16 @@ struct scheduler_ops {
 	 * This operation is optional.
 	 */
 	int (*scheduler_restore)(void *data);
+
+	/**
+	 * Initializes context
+	 * @param data Private data of selected scheduler.
+	 * @param task task that needs to be scheduled
+	 * @return thread that will be used to run the scheduled task
+	 *
+	 * This operation is optional.
+	 */
+	struct k_thread *(*scheduler_init_context)(void *data, struct task *task);
 };
 
 /** \brief Holds information about scheduler. */
@@ -379,6 +389,24 @@ static inline int schedulers_restore(void)
 	return 0;
 }
 
+/** See scheduler_ops::scheduler_init_context */
+static inline struct k_thread *scheduler_init_context(struct task *task)
+{
+	struct schedulers *schedulers = *arch_schedulers_get();
+	struct schedule_data *sch;
+	struct list_item *slist;
+
+	assert(schedulers);
+
+	list_for_item(slist, &schedulers->list) {
+		sch = container_of(slist, struct schedule_data, list);
+		if (task->type == sch->type && sch->ops->scheduler_init_context)
+			return sch->ops->scheduler_init_context(sch->data, task);
+	}
+
+	return NULL;
+}
+
 /**
  * Initializes scheduling task.
  * @param task Task to be initialized.