xtimer: rework dependecies to ease backend switch

boards/common/microbit/Kconfig

@@ -7,5 +7,5 @@
 config MODULE_MICROBIT
     bool "BBC micro:bit specific LED matrix handling"
     select MODULE_ZTIMER
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC
     select MODULE_MINEPLEX

cpu/lpc23xx/mci/Kconfig

@@ -9,4 +9,4 @@ config MODULE_MCI
     bool "LPC23XX Multimedia Card Interface (MCI) driver"
     depends on CPU_FAM_LPC23XX
     depends on TEST_KCONFIG
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC

cpu/native/Kconfig

@@ -26,6 +26,8 @@ config CPU_ARCH_NATIVE
     # needed modules
     select MODULE_PERIPH if TEST_KCONFIG
     select MODULE_ZTIMER64_XTIMER_COMPAT if MODULE_ZTIMER_XTIMER_COMPAT
+    select MODULE_ZTIMER64_USEC if MODULE_ZTIMER_XTIMER_COMPAT
+    select MODULE_ZTIMER64 if MODULE_ZTIMER_XTIMER_COMPAT
 
 config CPU_CORE_NATIVE
     bool

cpu/qn908x/periph/Kconfig

@@ -21,6 +21,4 @@ config MODULE_PERIPH_GPIO_MUX
 config MODULE_PERIPH_ADC
     bool "ADC peripheral driver"
     depends on HAS_PERIPH_ADC
-    select MODULE_ZTIMER
     select MODULE_ZTIMER_USEC
-    select MODULE_ZTIMER_PERIPH_TIMER

drivers/at30tse75x/Kconfig

@@ -11,7 +11,7 @@ config MODULE_AT30TSE75X
     depends on TEST_KCONFIG
     select MODULE_PERIPH_I2C
     select MODULE_ZTIMER
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC
     help
         AT30TSE75x temperature sensor with serial EEPROM.
 

drivers/ccs811/Kconfig

@@ -14,9 +14,7 @@ menuconfig MODULE_CCS811
     depends on TEST_KCONFIG
     select MODULE_PERIPH_GPIO
     select MODULE_PERIPH_I2C
-    select MODULE_ZTIMER
     select MODULE_ZTIMER_USEC
-    select MODULE_ZTIMER_PERIPH_TIMER
 
 config MODULE_CCS811_FULL
     bool "Full functionalities"

drivers/dsp0401/Kconfig

@@ -13,7 +13,7 @@ config MODULE_DSP0401
     select MODULE_PERIPH_GPIO
     select MODULE_PERIPH_PWM
     select MODULE_ZTIMER
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC
 
 config HAVE_DSP0401
     bool

drivers/ltc4150/Kconfig

@@ -12,7 +12,10 @@ config MODULE_LTC4150
     depends on TEST_KCONFIG
     select MODULE_PERIPH_GPIO
     select MODULE_PERIPH_GPIO_IRQ
-    select ZTIMER64_USEC
+    select MODULE_ZTIMER_USEC
+    select MODULE_ZTIMER
+    select MODULE_ZTIMER64_USEC
+    select MODULE_ZTIMER64
     help
         Driver for the Linear Tech LTC4150 Coulomb Counter (a.k.a. battery
         gauge sensor or power consumption sensor).

drivers/nvram_spi/Kconfig

@@ -11,4 +11,4 @@ config MODULE_NVRAM_SPI
     depends on TEST_KCONFIG
     select MODULE_NVRAM
     select MODULE_PERIPH_SPI
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC

drivers/pir/Kconfig

@@ -12,7 +12,10 @@ config MODULE_PIR
     depends on TEST_KCONFIG
     select MODULE_PERIPH_GPIO
     select MODULE_PERIPH_GPIO_IRQ
-    select ZTIMER64_USEC
+    select MODULE_ZTIMER64_USEC
+    select MODULE_ZTIMER64
+    select MODULE_ZTIMER_USEC
+    select MODULE_ZTIMER
 
 config HAVE_PIR
     bool

drivers/sdcard_spi/Kconfig

@@ -15,7 +15,7 @@ config MODULE_SDCARD_SPI
     select MODULE_PERIPH_SPI_RECONFIGURE if HAS_PERIPH_SPI_RECONFIGURE
     select MODULE_CHECKSUM
     select MODULE_ZTIMER
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC
 
 config HAVE_SDCARD_SPI
     bool

drivers/sgp30/Kconfig

@@ -13,9 +13,7 @@ menuconfig MODULE_SGP30
     depends on TEST_KCONFIG
     select MODULE_CHECKSUM
     select MODULE_PERIPH_I2C
-    select MODULE_ZTIMER
-    select MODULE_ZTIMER_PERIPH_TIMER
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC
 
 config MODULE_SGP30_STRICT
     bool "Strict reading period"

drivers/si1133/Kconfig

@@ -11,7 +11,7 @@ config MODULE_SI1133
     depends on TEST_KCONFIG
     select MODULE_PERIPH_I2C
     select MODULE_ZTIMER
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC
 
 config HAVE_SI1133
     bool

drivers/sm_pwm_01c/Kconfig

@@ -13,9 +13,7 @@ menuconfig MODULE_SM_PWM_01C
     depends on TEST_KCONFIG
     select MODULE_PERIPH_GPIO
     select MODULE_PERIPH_GPIO_IRQ
-    select MODULE_ZTIMER
-    select ZTIMER_USEC
-    select MODULE_ZTIMER_PERIPH_TIMER
+    select MODULE_ZTIMER_USEC
 
 config MODULE_SM_PWM_01C_MA
     bool "Use a moving average for sensor values"

kconfigs/Kconfig.ztimer_only

@@ -7,8 +7,7 @@
 config HAVE_ZTIMER_ONLY
     bool
     default y
-    select MODULE_ZTIMER if MODULE_XTIMER
-    select MODULE_ZTIMER_PERIPH_TIMER if MODULE_XTIMER
+    select MODULE_ZTIMER_USEC if MODULE_XTIMER
     help
         Indicates that the board cannot generate a clock frequency suitable for
         xtimer and requires ztimer for conversion. ztimer is used as backend.

makefiles/boards/ztimer_only.dep.mk

@@ -7,5 +7,6 @@
 ifneq (,$(filter xtimer,$(USEMODULE)))
   ifeq (,$(filter ztimer_xtimer_compat ztimer64_xtimer_compat,$(USEMODULE)))
     USEMODULE += xtimer_on_ztimer
+    USEMODULE += ztimer_usec
   endif
 endif

makefiles/default_modules.deps.mk

@@ -13,3 +13,7 @@ endif
 ifneq (,$(filter auto_init_saul,$(USEMODULE)))
   USEMODULE += saul_init_devs
 endif
+
+ifneq (,$(filter xtimer_on_periph_timer,$(USEMODULE)))
+  USEMODULE += div
+endif

makefiles/pseudomodules.inc.mk

@@ -257,6 +257,9 @@ PSEUDOMODULES += vfs_default
 PSEUDOMODULES += wakaama_objects_%
 PSEUDOMODULES += wifi_enterprise
 PSEUDOMODULES += xtimer_on_ztimer
+PSEUDOMODULES += xtimer_on_periph_timer
+PSEUDOMODULES += ztimer_xtimer_compat
+PSEUDOMODULES += ztimer64_xtimer_compat
 PSEUDOMODULES += zptr
 PSEUDOMODULES += ztimer
 PSEUDOMODULES += ztimer_%

pkg/driver_sx126x/Kconfig

@@ -11,7 +11,7 @@ config PACKAGE_DRIVER_SX126X
     depends on HAS_PERIPH_SPI
     select MODULE_PERIPH_SPI
     select MODULE_ZTIMER
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC
     select MODULE_DRIVER_SX126X_HAL
 
 config MODULE_DRIVER_SX126X_HAL

pkg/u8g2/Kconfig

@@ -10,7 +10,6 @@ config PACKAGE_U8G2
     depends on TEST_KCONFIG
     depends on HAS_PERIPH_GPIO
     select MODULE_PERIPH_GPIO
-    select MODULE_ZTIMER
     select MODULE_ZTIMER_USEC
     select MODULE_U8G2_RIOT
     select MODULE_U8G2_CSRC

pkg/ucglib/Kconfig

@@ -10,7 +10,6 @@ config PACKAGE_UCGLIB
     depends on TEST_KCONFIG
     depends on HAS_PERIPH_GPIO
     select MODULE_PERIPH_GPIO
-    select MODULE_ZTIMER
     select MODULE_ZTIMER_USEC
     select MODULE_UCGLIB_RIOT
     select MODULE_UCGLIB_CSRC

sys/Kconfig

@@ -82,15 +82,17 @@ rsource "seq/Kconfig"
 rsource "shell/Kconfig"
 rsource "test_utils/Kconfig"
 rsource "timex/Kconfig"
+menu "Timers"
+rsource "xtimer/Kconfig"
+rsource "ztimer/Kconfig"
+rsource "ztimer64/Kconfig"
+endmenu # Timers
 rsource "trace/Kconfig"
 rsource "tsrb/Kconfig"
 rsource "uri_parser/Kconfig"
 rsource "usb/Kconfig"
 rsource "usb_board_reset/Kconfig"
 rsource "vfs/Kconfig"
-rsource "xtimer/Kconfig"
-rsource "ztimer/Kconfig"
-rsource "ztimer64/Kconfig"
 
 config MODULE_CPP
     bool "Use CPP compiler"

sys/Kconfig.newlib

@@ -19,6 +19,8 @@ config MODULE_NEWLIB_SYSCALLS_DEFAULT
     depends on !HAVE_CUSTOM_NEWLIB_SYSCALLS
     select MODULE_DIV
     select MODULE_ZTIMER64_XTIMER_COMPAT if MODULE_ZTIMER_XTIMER_COMPAT
+    select MODULE_ZTIMER64_USEC if MODULE_ZTIMER_XTIMER_COMPAT
+    select MODULE_ZTIMER64 if MODULE_ZTIMER_XTIMER_COMPAT
     help
         Default implementation of newlib system calls.
 

sys/Makefile.dep

@@ -857,20 +857,7 @@ endif
 
 # handle xtimer's deps. Needs to be done *after* ztimer
 ifneq (,$(filter xtimer,$(USEMODULE)))
-  ifeq (,$(filter ztimer_xtimer_compat,$(USEMODULE)))
-    # xtimer is used, ztimer xtimer wrapper is not
-    DEFAULT_MODULE += auto_init_xtimer
-    USEMODULE += div
-    ifeq (,$(filter xtimer_on_ztimer,$(USEMODULE)))
-      # ztimer is not used, so use *periph_timer as low-level timer*.
-      FEATURES_REQUIRED += periph_timer
-    else
-      # will use *ztimer_usec as low-level timer*
-    endif
-  else
-    # ztimer_xtimer_compat is used, all of *xtimer's API will be mapped on ztimer
-    # or ztimer64 *
-  endif
+  include $(RIOTBASE)/sys/xtimer/Makefile.dep
 endif
 
 ifneq (,$(filter devfs_hwrng,$(USEMODULE)))

sys/arduino/Kconfig

@@ -25,7 +25,7 @@ menuconfig MODULE_ARDUINO
     select MODULE_FMT
     select MODULE_ZTIMER
     select MODULE_ZTIMER_MSEC
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC
 
 config MODULE_ARDUINO_PWM
     bool "PWM support for Arduino"

sys/benchmark/Kconfig

@@ -8,5 +8,5 @@
 config MODULE_BENCHMARK
     bool "Simple benchmarks support"
     select MODULE_ZTIMER
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC
     depends on TEST_KCONFIG

sys/event/Kconfig

@@ -49,6 +49,6 @@ config MODULE_EVENT_TIMEOUT_ZTIMER
 config MODULE_EVENT_TIMEOUT
     bool "Legacy API, support for triggering events after timeout"
     select MODULE_EVENT_TIMEOUT_ZTIMER
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC
 
 endif # MODULE_EVENT

sys/schedstatistics/Kconfig

@@ -7,6 +7,6 @@
 
 config MODULE_SCHEDSTATISTICS
     bool "Scheduler statistics support"
-    select ZTIMER_USEC
+    select MODULE_ZTIMER_USEC
     depends on TEST_KCONFIG
     select MODULE_SCHED_CB

sys/sema/Kconfig

@@ -13,4 +13,5 @@ config MODULE_SEMA
 config MODULE_SEMA_DEPRECATED
     bool "Semaphore compatible with 64bit timeouts, deprecated"
     select MODULE_SEMA
-    select ZTIMER64_USEC
+    select MODULE_ZTIMER64_USEC
+    select MODULE_ZTIMER64

sys/shell/commands/sc_gnrc_udp.c

@@ -31,9 +31,10 @@
 #include "net/utils.h"
 #include "timex.h"
 #include "utlist.h"
-#if IS_USED(MODULE_ZTIMER)
+#if IS_USED(MODULE_ZTIMER_USEC) || IS_USED(MODULE_ZTIMER_MSEC)
 #include "ztimer.h"
-#else
+#endif
+#if IS_USED(MODULE_XTIMER)
 #include "xtimer.h"
 #endif
 

sys/trace/Kconfig

@@ -8,6 +8,4 @@
 config MODULE_TRACE
     bool "Trace program flows"
     depends on TEST_KCONFIG
-    select MODULE_ZTIMER
     select MODULE_ZTIMER_USEC
-    select MODULE_ZTIMER_PERIPH_TIMER

sys/xtimer/Kconfig

@@ -7,18 +7,48 @@
 
 menuconfig MODULE_XTIMER
     bool "xtimer"
-    depends on HAS_PERIPH_TIMER
     depends on TEST_KCONFIG
-    # use timer peripheral unless ztimer compatibility module is used
-    select MODULE_PERIPH_TIMER if HAS_PERIPH_TIMER && !MODULE_XTIMER_ON_ZTIMER && !MODULE_ZTIMER_XTIMER_COMPAT && !MODULE_ZTIMER64_XTIMER_COMPAT
-
-    select MODULE_DIV if !MODULE_ZTIMER_XTIMER_COMPAT
+    depends on HAS_PERIPH_TIMER
+    select MODULE_PERIPH_TIMER
     help
         Include xtimer module. xtimer requires a low-level timer implementation
-        that can be provided either by a peripheral timer or the ztimer module
-        when MODULE_XTIMER_ON_ZTIMER is enabled.
+        that can be provided either by a peripheral timer or the ztimer module.
+
+if MODULE_XTIMER
+
+config XTIMER_ZTIMER_BACKEND
+    bool "xtimer always implemented by ztimer"
+    select MODULE_ZTIMER_USEC
+
+choice XTIMER_BACKEND
+    bool "xtimer backend"
+
+config MODULE_XTIMER_ON_ZTIMER
+    bool "xtimer api implemented by xtimer, with ztimer_usec backend"
+    depends on MODULE_ZTIMER_PERIPH_TIMER
+    depends on MODULE_ZTIMER
+
+config MODULE_ZTIMER_XTIMER_COMPAT
+    bool "xtimer api implemented by ztimer"
+    depends on MODULE_ZTIMER_USEC
+    select MODULE_DIV
+
+config MODULE_XTIMER_ON_PERIPH_TIMER
+    bool "xtimer api implemented by xtimer, with periph_timer backend"
+    select MODULE_DIV
+endchoice
+
+config MODULE_ZTIMER64_XTIMER_COMPAT
+    bool "xtimer api implemented bt ztimer64"
+    select MODULE_DIV
+    depends on MODULE_ZTIMER64
+    depends on MODULE_ZTIMER64_USEC
+    depends on MODULE_ZTIMER_XTIMER_COMPAT
+    help
+        This is a wrapper of xtimer API on ztimer64_usec.
 
 config MODULE_AUTO_INIT_XTIMER
     bool "Auto-init xtimer"
-    default y if MODULE_AUTO_INIT && !MODULE_ZTIMER_XTIMER_COMPAT
-    depends on MODULE_XTIMER
+    default y if MODULE_AUTO_INIT && (MODULE_XTIMER && !MODULE_ZTIMER_XTIMER_COMPAT)
+
+endif # MODULE_XTIMER

sys/xtimer/Makefile.dep

@@ -0,0 +1,36 @@
+DEFAULT_MODULE += auto_init_xtimer
+# In whatever combination of backends periph_timer will be required
+# - xtimer_on_ztimer -> ztimer_usec -> ztimer_periph_timer -> periph_timer
+# - xtimer_on_periph_timer -> periph_timer
+# - ztimer_xtimer_compat -> ztimer_usec -> ztimer_periph_timer -> periph_timer
+# But requesting it here allows us to select `xtimer_on_periph_timer` only
+# at the end of dependency resolution if `ztimer_periph_timer` was not selected
+# without having an ifeq dependency that would be subject to dependency inclusion
+# order issues, this way xtimer_on_periph_timer can be turned into a DEFAULT_MODULE
+# that can be disabled if ztimer_periph_timer
+FEATURES_REQUIRED += periph_timer
+DEFAULT_MODULE += xtimer_on_periph_timer
+
+# To avoid inclusion order changing dependencies this dependency is commented out
+# but it models xtimer_on_periph_timer dependency explicitly, see comment above
+# for more details
+# ifneq (,$(filter xtimer_on_periph_timer,$(USEMODULE)))
+  # USEMODULE += div
+  # FEATURES_REQUIRED += periph_timer
+# endif
+
+ifneq (,$(filter ztimer_periph_timer,$(USEMODULE)))
+  DISABLE_MODULE += xtimer_on_periph_timer
+  ifeq (,$(filter ztimer_xtimer_compat,$(USEMODULE)))
+    USEMODULE += xtimer_on_ztimer
+  endif
+endif
+
+ifneq (,$(filter ztimer_xtimer_compat,$(USEMODULE)))
+  DISABLE_MODULE += auto_init_xtimer
+endif
+
+# make xtimer use ztimer_usec as low level timer
+ifneq (,$(filter xtimer_on_ztimer,$(USEMODULE)))
+  USEMODULE += ztimer_periph_timer
+endif