sys/event/timeout: split xtimer, ztimer backends, don't force usec

This PR makes `event_timeout` and `event_timeout_ztimer` two distinct
pseudomodules, where the only api difference is in the init function.

If only `event_timeout_ztimer` is selected then no default ZTIMER
backend is selected and the old init function is not implemented.

If only `event_timeout` is selected then `xtimer` is used unless
`ztimer_usec` is included. In which case the `xtimer` wrapper on top
of `ztimer` is used and `xtimer` is not directly selected. This
allows for the legacy api to be supported with `ztimer_usec` as
a drop-in replacement.

If `event_timeout` and `event_timeut_ztimer` are selected then
`event_timeout` SRC file is excluded from compilation.

makefiles/pseudomodules.inc.mk

@@ -25,6 +25,7 @@ PSEUDOMODULES += dhcpv6_relay
 PSEUDOMODULES += dns_msg
 PSEUDOMODULES += ecc_%
 PSEUDOMODULES += event_%
+PSEUDOMODULES += event_timeout
 PSEUDOMODULES += event_timeout_ztimer
 PSEUDOMODULES += evtimer_mbox
 PSEUDOMODULES += evtimer_on_ztimer

sys/Makefile.dep

@@ -512,22 +512,24 @@ ifneq (,$(filter event_thread_%,$(USEMODULE)))
 endif
 
 ifneq (,$(filter event_timeout_ztimer,$(USEMODULE)))
-  USEMODULE += event_timeout
+  USEMODULE += ztimer
-endif
-
-ifneq (,$(filter event_periodic_timeout,$(USEMODULE)))
-  USEMODULE += event_timeout
-  USEMODULE += ztimer_periodic
 endif
 
 ifneq (,$(filter event_timeout,$(USEMODULE)))
   ifneq (,$(filter event_timeout_ztimer,$(USEMODULE)))
     USEMODULE += ztimer_usec
   else
-    USEMODULE += xtimer
+    ifeq (,$(filter ztimer_usec,$(USEMODULE)))
+      USEMODULE += xtimer
+    endif
   endif
 endif
 
+ifneq (,$(filter event_periodic_timeout,$(USEMODULE)))
+  USEMODULE += event_timeout
+  USEMODULE += ztimer_periodic
+endif
+
 ifneq (,$(filter event,$(USEMODULE)))
   USEMODULE += core_thread_flags
 endif

sys/event/Kconfig

@@ -39,8 +39,30 @@ config MODULE_EVENT_THREAD_HIGHEST
 
 endif # MODULE_EVENT_THREAD
 
+config MODULE_EVENT_TIMEOUT_ZTIMER
+    bool "Support for triggering events after timeout, ztimer backend"
+    select MODULE_ZTIMER
+
 config MODULE_EVENT_TIMEOUT
-    bool "Support for triggering events after timeout"
+    bool "Legacy API, support for triggering events after timeout"
-    select MODULE_XTIMER
+
+if MODULE_EVENT_TIMEOUT
+
+choice EVENT_TIMEOUT_IMPLEMENTATION
+    bool "Event Timeout Implementation"
+    default EVENT_TIMEOUT_ON_XTIMER
+
+config EVENT_TIMEOUT_ON_ZTIMER
+    bool "Use ztimer as backend"
+    select MODULE_EVENT_TIMEOUT_ZTIMER
+    select MODULE_ZTIMER_USEC
+
+config EVENT_TIMEOUT_ON_XTIMER
+    bool "Use xtimer as backend"
+    select MODULE_XTIMER if !ZTIMER_USEC
+
+endchoice # EVENT_TIMEOUT_IMPLEMENTATION
+
+endif # MODULE_EVENT_TIMEOUT
 
 endif # MODULE_EVENT

sys/event/Makefile

@@ -2,4 +2,10 @@ SRC := event.c
 
 SUBMODULES := 1
 
+ifneq (,$(filter event_timeout_ztimer,$(USEMODULE)))
+  ifneq (,$(filter ztimer_usec,$(USEMODULE)))
+    SUBMODULES_NO_SRC += timeout.c
+  endif
+endif
+
 include $(RIOTBASE)/Makefile.base

sys/event/timeout.c

@@ -9,20 +9,21 @@
  */
 
 #include "kernel_defines.h"
-#if IS_USED(MODULE_EVENT_TIMEOUT_ZTIMER)
+#include "event/timeout.h"
-#include "ztimer.h"
+#if IS_USED(MODULE_ZTIMER_USEC)
+#include "ztimer/xtimer_compat.h"
 #else
 #include "xtimer.h"
 #endif
-#include "event/timeout.h"
 
 static void _event_timeout_callback(void *arg)
 {
     event_timeout_t *event_timeout = (event_timeout_t *)arg;
+
     event_post(event_timeout->queue, event_timeout->event);
 }
 
-static void _event_timeout_init(event_timeout_t *event_timeout, event_queue_t *queue, event_t *event)
+void event_timeout_init(event_timeout_t *event_timeout, event_queue_t *queue, event_t *event)
 {
     event_timeout->timer.callback = _event_timeout_callback;
     event_timeout->timer.arg = event_timeout;
@@ -30,40 +31,12 @@ static void _event_timeout_init(event_timeout_t *event_timeout, event_queue_t *q
     event_timeout->event = event;
 }
 
-void event_timeout_init(event_timeout_t *event_timeout, event_queue_t *queue, event_t *event)
-{
-#if IS_USED(MODULE_EVENT_TIMEOUT_ZTIMER)
-    event_timeout_ztimer_init(event_timeout, ZTIMER_USEC, queue, event);
-#else
-    _event_timeout_init(event_timeout, queue, event);
-#endif
-}
-
-#if IS_USED(MODULE_EVENT_TIMEOUT_ZTIMER)
-void event_timeout_ztimer_init(event_timeout_t *event_timeout, ztimer_clock_t* clock,
-                               event_queue_t *queue, event_t *event)
-{
-    event_timeout->clock = clock;
-    _event_timeout_init(event_timeout, queue, event);
-}
-#endif
-
 void event_timeout_set(event_timeout_t *event_timeout, uint32_t timeout)
 {
-#if IS_USED(MODULE_EVENT_TIMEOUT_ZTIMER)
-    ztimer_set(event_timeout->clock, &event_timeout->timer, timeout);
-#else
     xtimer_set(&event_timeout->timer, timeout);
-#endif
 }
 
 void event_timeout_clear(event_timeout_t *event_timeout)
 {
-#if IS_USED(MODULE_EVENT_TIMEOUT_ZTIMER)
-    if (event_timeout->clock) {
-        ztimer_remove(event_timeout->clock, &event_timeout->timer);
-    }
-#else
     xtimer_remove(&event_timeout->timer);
-#endif
 }

sys/event/timeout_ztimer.c

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2017 Inria
+ *               2017 Freie Universität Berlin
+ *               2017 Kaspar Schleiser <kaspar@schleiser.de>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+#include "kernel_defines.h"
+#include "event/timeout.h"
+#include "ztimer.h"
+
+static void _event_timeout_callback(void *arg)
+{
+    event_timeout_t *event_timeout = (event_timeout_t *)arg;
+
+    event_post(event_timeout->queue, event_timeout->event);
+}
+
+#if IS_USED(MODULE_EVENT_TIMEOUT)
+void event_timeout_init(event_timeout_t *event_timeout, event_queue_t *queue, event_t *event)
+{
+    event_timeout_ztimer_init(event_timeout, ZTIMER_USEC, queue, event);
+}
+#endif
+
+void event_timeout_ztimer_init(event_timeout_t *event_timeout, ztimer_clock_t *clock,
+                               event_queue_t *queue, event_t *event)
+{
+    event_timeout->clock = clock;
+    event_timeout->timer.callback = _event_timeout_callback;
+    event_timeout->timer.arg = event_timeout;
+    event_timeout->queue = queue;
+    event_timeout->event = event;
+}
+
+void event_timeout_set(event_timeout_t *event_timeout, uint32_t timeout)
+{
+    ztimer_set(event_timeout->clock, &event_timeout->timer, timeout);
+}
+
+void event_timeout_clear(event_timeout_t *event_timeout)
+{
+    if (event_timeout->clock) {
+        ztimer_remove(event_timeout->clock, &event_timeout->timer);
+    }
+}

sys/include/event/timeout.h

@@ -38,7 +38,7 @@
 #define EVENT_TIMEOUT_H
 
 #include "event.h"
-#if IS_USED(MODULE_EVENT_TIMEOUT_ZTIMER)
+#if IS_USED(MODULE_EVENT_TIMEOUT_ZTIMER) || IS_USED(MODULE_ZTIMER_USEC)
 #include "ztimer.h"
 #else
 #include "xtimer.h"
@@ -53,8 +53,10 @@ extern "C" {
  */
 typedef struct {
 #if IS_USED(MODULE_EVENT_TIMEOUT_ZTIMER)
-    ztimer_t timer;         /**< ztimer object used for timeout */
     ztimer_clock_t *clock;  /**< ztimer clock to use */
+#endif
+#if IS_USED(MODULE_EVENT_TIMEOUT_ZTIMER) || IS_USED(MODULE_ZTIMER_USEC)
+    ztimer_t timer;         /**< ztimer object used for timeout */
 #else
     xtimer_t timer;         /**< ztimer object used for timeout */
 #endif
@@ -75,6 +77,7 @@ void event_timeout_ztimer_init(event_timeout_t *event_timeout, ztimer_clock_t *c
                                event_queue_t *queue, event_t *event);
 #endif
 
+#if IS_USED(MODULE_EVENT_TIMEOUT) || DOXYGEN
 /**
  * @brief   Initialize timeout event object
  *
@@ -86,6 +89,7 @@ void event_timeout_ztimer_init(event_timeout_t *event_timeout, ztimer_clock_t *c
  */
 void event_timeout_init(event_timeout_t *event_timeout, event_queue_t *queue,
                         event_t *event);
+#endif
 
 /**
  * @brief   Set a timeout