service: Introduce software service instanciation macros

SERVICE_INSTANCE_INIT_ONCE is a direct replacement for SYS_INIT_NAMED,
removing the priority parameter as it is now provided by
gen_init_priorities.py script.

No alias will be created for SYS_INIT as we seek to limit the usage of
SERVICE_INSTANCE_INIT_ONCE, on the contrary to SYS_INIT which got widely
abused in the past.

Signed-off-by: Tomasz Bursztyka <[email protected]>

Author: tbursztyka

include/zephyr/service.h

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2024 Tomasz Bursztyka
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_SERVICE_H_
+#define ZEPHYR_INCLUDE_SERVICE_H_
+
+#include <zephyr/init.h>
+
+#include <zephyr/sys/util_init.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @defgroup service Service instanciation
+ * @ingroup os_services
+ *
+ * Zephyr offers an infrastructure to instanciate software services, that
+ * can be initialized at boot time, following the levels described in init.h
+ *
+ * @{
+ */
+
+/**
+ * @brief Register a software service to be initialized only once
+ *
+ * @param name A unique name identifying the service (can reuse init_fn)
+ * @param init_func Service initialization function.
+ * @param level Default service initialization level. Allowed tokens: `EARLY`,
+ *`PRE_KERNEL_1`, `PRE_KERNEL_2`, `POST_KERNEL`, `APPLICATION` and `SMP` if
+ * @kconfig{CONFIG_SMP} is enabled. Which default level can be superceded by a computed
+ * one (see scripts/gen_init_priorities.py)
+ */
+#define SERVICE_INSTANCE_INIT_ONCE(name, init_func, level)                        \
+	Z_SERVICE_INSTANCE_INIT_ONCE(name, init_func,                             \
+				     ZINIT_GET_LEVEL(name, level),                \
+				     ZINIT_GET_PRIORITY(name, name))
+
+/** @cond INTERNAL_HIDDEN */
+
+#define Z_SERVICE_INSTANCE_INIT_ONCE(name, init_func, level, prio)                \
+	static const Z_DECL_ALIGN(struct init_entry) __used __noasan              \
+		Z_INIT_ENTRY_SECTION(level, prio)                                 \
+		Z_INIT_ENTRY_NAME(name) = {.init_fn = {.sys = (init_func)},       \
+			Z_INIT_SYS_INIT_DEV_NULL}
+
+/** @endcond */
+
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_INCLUDE_SERVICE_H_ */