cobalt/sched: dovetail: add placeholders for context switching

Signed-off-by: Philippe Gerum <rpm@xenomai.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

include/cobalt/kernel/dovetail/pipeline/sched.h

+/*
+ * SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2020 Philippe Gerum  <rpm@xenomai.org>
+ */
+
+#ifndef _COBALT_KERNEL_DOVETAIL_SCHED_H
+#define _COBALT_KERNEL_DOVETAIL_SCHED_H
+
+struct xnthread;
+struct xnsched;
+struct task_struct;
+
+void pipeline_init_shadow_tcb(struct xnthread *thread);
+
+void pipeline_init_root_tcb(struct xnthread *thread);
+
+int ___xnsched_run(struct xnsched *sched);
+
+static inline int pipeline_schedule(struct xnsched *sched)
+{
+	return run_oob_call((int (*)(void *))___xnsched_run, sched);
+}
+
+static inline void pipeline_prep_switch_oob(struct xnthread *root)
+{
+	/* N/A */
+}
+
+bool pipeline_switch_to(struct xnthread *prev,
+			struct xnthread *next,
+			bool leaving_inband);
+
+int pipeline_leave_inband(void);
+
+int pipeline_leave_oob_prepare(void);
+
+void pipeline_leave_oob_finish(void);
+
+static inline
+void pipeline_finalize_thread(struct xnthread *thread)
+{
+	/* N/A */
+}
+
+void pipeline_raise_mayday(struct task_struct *tsk);
+
+void pipeline_clear_mayday(void);
+
+#endif /* !_COBALT_KERNEL_DOVETAIL_SCHED_H */

kernel/cobalt/dovetail/Makefile

@@ -2,4 +2,4 @@ ccflags-y += -I$(srctree)/kernel
 
 obj-y +=	pipeline.o
 
-pipeline-y :=	init.o kevents.o
+pipeline-y :=	init.o kevents.o sched.o

kernel/cobalt/dovetail/sched.c

+/*
+ * SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2001-2020 Philippe Gerum <rpm@xenomai.org>.
+ */
+
+#include <linux/cpuidle.h>
+#include <cobalt/kernel/thread.h>
+#include <cobalt/kernel/sched.h>
+#include <pipeline/sched.h>
+#include <trace/events/cobalt-core.h>
+
+/* in-band stage, hard_irqs_disabled() */
+bool irq_cpuidle_control(struct cpuidle_device *dev,
+			struct cpuidle_state *state)
+{
+	/*
+	 * Deny entering sleep state if this entails stopping the
+	 * timer (i.e. C3STOP misfeature).
+	 */
+	if (state && (state->flags & CPUIDLE_FLAG_TIMER_STOP))
+		return false;
+
+	return true;
+}
+
+bool pipeline_switch_to(struct xnthread *prev, struct xnthread *next,
+			bool leaving_inband)
+{
+	return dovetail_context_switch(&xnthread_archtcb(prev)->altsched,
+			&xnthread_archtcb(next)->altsched, leaving_inband);
+}
+
+void pipeline_init_shadow_tcb(struct xnthread *thread)
+{
+	/*
+	 * Initialize the alternate scheduling control block.
+	 */
+	TODO();
+
+	trace_cobalt_shadow_map(thread);
+}
+
+void pipeline_init_root_tcb(struct xnthread *thread)
+{
+	/*
+	 * Initialize the alternate scheduling control block.
+	 */
+	TODO();
+}
+
+int pipeline_leave_inband(void)
+{
+	return dovetail_leave_inband();
+}
+
+int pipeline_leave_oob_prepare(void)
+{
+	dovetail_leave_oob();
+
+	return XNRELAX;
+}
+
+void pipeline_leave_oob_finish(void)
+{
+	dovetail_resume_inband();
+}
+
+void pipeline_raise_mayday(struct task_struct *tsk)
+{
+	dovetail_send_mayday(tsk);
+}
+
+void pipeline_clear_mayday(void) /* May solely affect current. */
+{
+	clear_thread_flag(TIF_MAYDAY);
+}