rtos/mutex.h: add wrappers for Zephyr sys/mutex.h interface

To enable use of Zephyr sys/mutex.h interface in SOF audio pipeline
code, add a rtos/mutex.h wrapper for this. In Zephyr build, the native
Zephyr interface is used and in posix builds (e.g. testbench), a no-op
implementation is provided (similarly that already exists for k_mutex).

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

Author: kv2019i

posix/include/rtos/mutex.h

@@ -40,4 +40,26 @@ static inline int k_mutex_unlock(struct k_mutex *mutex)
 	return 0;
 }
 
+/* provide a no-op implementation for zephyr/sys/mutex.h */
+
+struct sys_mutex {
+};
+
+#define SYS_MUTEX_DEFINE(name) \
+	struct sys_mutex name
+
+static inline void sys_mutex_init(struct sys_mutex *mutex)
+{
+}
+
+static inline int sys_mutex_lock(struct sys_mutex *mutex, k_timeout_t timeout)
+{
+	return 0;
+}
+
+static inline int sys_mutex_unlock(struct sys_mutex *mutex)
+{
+	return 0;
+}
+
 #endif

zephyr/include/rtos/mutex.h

@@ -7,5 +7,6 @@
 #define __ZEPHYR_RTOS_MUTEX_H__
 
 #include <zephyr/kernel.h> /* k_mutex_*() */
+#include <zephyr/sys/mutex.h> /* for sys_mutex */
 
 #endif /* __ZEPHYR_RTOS_MUTEX_H__ */