extmod/machine_wdt: Factor ports' WDT Python bindings to common code.

There are currently 7 ports that implement machine.WDT and a lot of code is
duplicated across these implementations.  This commit factors the common
parts of all these implementations to a single location in
extmod/machine_wdt.c.  This common code provides the top-level Python
bindings (class and method wrappers), and then each port implements the
back end specific to that port.

With this refactor the ports remain functionally the same except for:

- The esp8266 WDT constructor now takes keyword arguments, and accepts the
  "timeout" argument but raises an exception if it's not the default value
  (this port doesn't support changing the timeout).

- The mimxrt and samd ports now interpret the argument to WDT.timeout_ms()
  as signed and if it's negative truncate it to the minimum timeout (rather
  than it being unsigned and a negative value truncating to the maximum
  timeout).

Signed-off-by: Damien George <damien@micropython.org>

38 files changed, 235 insertions, 304 deletions

diff --git a/extmod/extmod.cmake b/extmod/extmod.cmake
index c8756a682..063df70f5 100644
--- a/extmod/extmod.cmake
+++ b/extmod/extmod.cmake
@@ -14,6 +14,7 @@ set(MICROPY_SOURCE_EXTMOD
     ${MICROPY_EXTMOD_DIR}/machine_pwm.c
     ${MICROPY_EXTMOD_DIR}/machine_signal.c
     ${MICROPY_EXTMOD_DIR}/machine_spi.c
+    ${MICROPY_EXTMOD_DIR}/machine_wdt.c
     ${MICROPY_EXTMOD_DIR}/modbluetooth.c
     ${MICROPY_EXTMOD_DIR}/modframebuf.c
     ${MICROPY_EXTMOD_DIR}/modlwip.c
diff --git a/extmod/extmod.mk b/extmod/extmod.mk
index f776a7f69..a6c782686 100644
--- a/extmod/extmod.mk
+++ b/extmod/extmod.mk
@@ -11,6 +11,7 @@ SRC_EXTMOD_C += \
 	extmod/machine_signal.c \
 	extmod/machine_spi.c \
 	extmod/machine_timer.c \
+	extmod/machine_wdt.c \
 	extmod/modasyncio.c \
 	extmod/modbinascii.c \
 	extmod/modbluetooth.c \
diff --git a/extmod/machine_wdt.c b/extmod/machine_wdt.c
new file mode 100644
index 000000000..a49484ed8
--- /dev/null
+++ b/extmod/machine_wdt.c
@@ -0,0 +1,95 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020-2023 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+
+#if MICROPY_PY_MACHINE_WDT
+
+#include "extmod/modmachine.h"
+
+// The port must provide implementations of these low-level WDT functions.
+STATIC machine_wdt_obj_t *mp_machine_wdt_make_new_instance(mp_int_t id, mp_int_t timeout_ms);
+STATIC void mp_machine_wdt_feed(machine_wdt_obj_t *self);
+#if MICROPY_PY_MACHINE_WDT_TIMEOUT_MS
+STATIC void mp_machine_wdt_timeout_ms_set(machine_wdt_obj_t *self_in, mp_int_t timeout_ms);
+#endif
+
+// The port provides implementations of the above in this file.
+#include MICROPY_PY_MACHINE_WDT_INCLUDEFILE
+
+STATIC mp_obj_t machine_wdt_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
+    enum { ARG_id, ARG_timeout };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_id, MP_ARG_INT, {.u_int = 0} },
+        { MP_QSTR_timeout, MP_ARG_INT, {.u_int = 5000} },
+    };
+
+    // Parse the arguments.
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    // Create WDT instance.
+    machine_wdt_obj_t *self = mp_machine_wdt_make_new_instance(args[ARG_id].u_int, args[ARG_timeout].u_int);
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+// WDT.feed()
+STATIC mp_obj_t machine_wdt_feed(mp_obj_t self_in) {
+    machine_wdt_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_machine_wdt_feed(self);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_wdt_feed_obj, machine_wdt_feed);
+
+#if MICROPY_PY_MACHINE_WDT_TIMEOUT_MS
+// WDT.timeout_ms(timeout)
+STATIC mp_obj_t machine_wdt_timeout_ms(mp_obj_t self_in, mp_obj_t timeout_in) {
+    machine_wdt_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_int_t timeout_ms = mp_obj_get_int(timeout_in);
+    mp_machine_wdt_timeout_ms_set(self, timeout_ms);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(machine_wdt_timeout_ms_obj, machine_wdt_timeout_ms);
+#endif
+
+STATIC const mp_rom_map_elem_t machine_wdt_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_feed), MP_ROM_PTR(&machine_wdt_feed_obj) },
+    #if MICROPY_PY_MACHINE_WDT_TIMEOUT_MS
+    { MP_ROM_QSTR(MP_QSTR_timeout_ms), MP_ROM_PTR(&machine_wdt_timeout_ms_obj) },
+    #endif
+};
+STATIC MP_DEFINE_CONST_DICT(machine_wdt_locals_dict, machine_wdt_locals_dict_table);
+
+MP_DEFINE_CONST_OBJ_TYPE(
+    machine_wdt_type,
+    MP_QSTR_WDT,
+    MP_TYPE_FLAG_NONE,
+    make_new, machine_wdt_make_new,
+    locals_dict, &machine_wdt_locals_dict
+    );
+
+#endif // MICROPY_PY_MACHINE_WDT
diff --git a/ports/stm32/wdt.h b/extmod/modmachine.h
index d60bb7e9e..794c62cde 100644
--- a/ports/stm32/wdt.h
+++ b/extmod/modmachine.h
@@ -3,7 +3,7 @@
  *
  * The MIT License (MIT)
  *
- * Copyright (c) 2016 Damien P. George
+ * Copyright (c) 2023 Damien P. George
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -23,9 +23,21 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
-#ifndef MICROPY_INCLUDED_STM32_WDT_H
-#define MICROPY_INCLUDED_STM32_WDT_H
 
-extern const mp_obj_type_t pyb_wdt_type;
+#ifndef MICROPY_INCLUDED_EXTMOD_MODMACHINE_H
+#define MICROPY_INCLUDED_EXTMOD_MODMACHINE_H
 
-#endif // MICROPY_INCLUDED_STM32_WDT_H
+#include "py/obj.h"
+
+// A port must provide these types, but they are otherwise opaque.
+typedef struct _machine_wdt_obj_t machine_wdt_obj_t;
+
+// These classes correspond to machine.Type entries in the machine module.
+// Their Python bindings are implemented in extmod, and their implementation
+// is provided by a port.
+extern const mp_obj_type_t machine_i2c_type;
+extern const mp_obj_type_t machine_spi_type;
+extern const mp_obj_type_t machine_timer_type;
+extern const mp_obj_type_t machine_wdt_type;
+
+#endif // MICROPY_INCLUDED_EXTMOD_MODMACHINE_H
diff --git a/ports/cc3200/application.mk b/ports/cc3200/application.mk
index f4487d69d..deee201ee 100644
--- a/ports/cc3200/application.mk
+++ b/ports/cc3200/application.mk
@@ -93,7 +93,6 @@ APP_MODS_SRC_C = $(addprefix mods/,\
 	pybspi.c \
 	pybtimer.c \
 	pybuart.c \
-	pybwdt.c \
 	)
 
 APP_CC3100_SRC_C = $(addprefix drivers/cc3100/src/,\
diff --git a/ports/cc3200/mods/pybwdt.c b/ports/cc3200/mods/machine_wdt.c
index 589f53cf1..b20ef7eb9 100644
--- a/ports/cc3200/mods/pybwdt.c
+++ b/ports/cc3200/mods/machine_wdt.c
@@ -24,11 +24,9 @@
  * THE SOFTWARE.
  */
 
-#include <stdint.h>
+// This file is never compiled standalone, it's included directly from
+// extmod/machine_wdt.c via MICROPY_PY_MACHINE_WDT_INCLUDEFILE.
 
-#include "py/mpconfig.h"
-#include "py/obj.h"
-#include "py/runtime.h"
 #include "py/mperrno.h"
 #include "py/mphal.h"
 #include "inc/hw_types.h"
@@ -40,8 +38,6 @@
 #include "prcm.h"
 #include "utils.h"
 #include "pybwdt.h"
-#include "mperror.h"
-
 
 /******************************************************************************
  DECLARE CONSTANTS
@@ -52,18 +48,18 @@
 /******************************************************************************
  DECLARE TYPES
  ******************************************************************************/
-typedef struct {
+typedef struct _machine_wdt_obj_t {
     mp_obj_base_t base;
     bool    servers;
     bool    servers_sleeping;
     bool    simplelink;
     bool    running;
-} pyb_wdt_obj_t;
+} machine_wdt_obj_t;
 
 /******************************************************************************
  DECLARE PRIVATE DATA
  ******************************************************************************/
-STATIC pyb_wdt_obj_t pyb_wdt_obj = {.servers = false, .servers_sleeping = false, .simplelink = false, .running = false};
+STATIC machine_wdt_obj_t machine_wdt_obj = {.servers = false, .servers_sleeping = false, .simplelink = false, .running = false};
 
 /******************************************************************************
  DEFINE PUBLIC FUNCTIONS
@@ -74,39 +70,28 @@ void pybwdt_init0 (void) {
 }
 
 void pybwdt_srv_alive (void) {
-    pyb_wdt_obj.servers = true;
+    machine_wdt_obj.servers = true;
 }
 
 void pybwdt_srv_sleeping (bool state) {
-    pyb_wdt_obj.servers_sleeping = state;
+    machine_wdt_obj.servers_sleeping = state;
 }
 
 void pybwdt_sl_alive (void) {
-    pyb_wdt_obj.simplelink = true;
+    machine_wdt_obj.simplelink = true;
 }
 
 /******************************************************************************/
 // MicroPython bindings
 
-STATIC const mp_arg_t pyb_wdt_init_args[] = {
-    { MP_QSTR_id,                             MP_ARG_OBJ,  {.u_obj = mp_const_none} },
-    { MP_QSTR_timeout,                        MP_ARG_INT,  {.u_int = 5000} },   // 5 s
-};
-STATIC mp_obj_t pyb_wdt_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
-    // check the arguments
-    mp_map_t kw_args;
-    mp_map_init_fixed_table(&kw_args, n_kw, all_args + n_args);
-    mp_arg_val_t args[MP_ARRAY_SIZE(pyb_wdt_init_args)];
-    mp_arg_parse_all(n_args, all_args, &kw_args, MP_ARRAY_SIZE(args), pyb_wdt_init_args, args);
-
-    if (args[0].u_obj != mp_const_none && mp_obj_get_int(args[0].u_obj) > 0) {
+STATIC machine_wdt_obj_t *mp_machine_wdt_make_new_instance(mp_int_t id, mp_int_t timeout_ms) {
+    if (id != 0) {
         mp_raise_OSError(MP_ENODEV);
     }
-    uint timeout_ms = args[1].u_int;
     if (timeout_ms < PYBWDT_MIN_TIMEOUT_MS) {
         mp_raise_ValueError(MP_ERROR_TEXT("invalid argument(s) value"));
     }
-    if (pyb_wdt_obj.running) {
+    if (machine_wdt_obj.running) {
         mp_raise_OSError(MP_EPERM);
     }
 
@@ -116,10 +101,10 @@ STATIC mp_obj_t pyb_wdt_make_new(const mp_obj_type_t *type, size_t n_args, size_
     // Unlock to be able to configure the registers
     MAP_WatchdogUnlock(WDT_BASE);
 
-#ifdef DEBUG
+    #ifdef DEBUG
     // make the WDT stall when the debugger stops on a breakpoint
     MAP_WatchdogStallEnable (WDT_BASE);
-#endif
+    #endif
 
     // set the watchdog timer reload value
     // the WDT trigger a system reset after the second timeout
@@ -128,33 +113,16 @@ STATIC mp_obj_t pyb_wdt_make_new(const mp_obj_type_t *type, size_t n_args, size_
 
     // start the timer. Once it's started, it cannot be disabled.
     MAP_WatchdogEnable(WDT_BASE);
-    pyb_wdt_obj.base.type = &pyb_wdt_type;
-    pyb_wdt_obj.running = true;
+    machine_wdt_obj.base.type = &machine_wdt_type;
+    machine_wdt_obj.running = true;
 
-    return (mp_obj_t)&pyb_wdt_obj;
+    return &machine_wdt_obj;
 }
 
-STATIC mp_obj_t pyb_wdt_feed(mp_obj_t self_in) {
-    pyb_wdt_obj_t *self = self_in;
+STATIC void mp_machine_wdt_feed(machine_wdt_obj_t *self) {
     if ((self->servers || self->servers_sleeping) && self->simplelink && self->running) {
         self->servers = false;
         self->simplelink = false;
         MAP_WatchdogIntClear(WDT_BASE);
     }
-    return mp_const_none;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_wdt_feed_obj, pyb_wdt_feed);
-
-STATIC const mp_rom_map_elem_t pybwdt_locals_dict_table[] = {
-    { MP_ROM_QSTR(MP_QSTR_feed), MP_ROM_PTR(&pyb_wdt_feed_obj) },
-};
-STATIC MP_DEFINE_CONST_DICT(pybwdt_locals_dict, pybwdt_locals_dict_table);
-
-MP_DEFINE_CONST_OBJ_TYPE(
-    pyb_wdt_type,
-    MP_QSTR_WDT,
-    MP_TYPE_FLAG_NONE,
-    make_new, pyb_wdt_make_new,
-    locals_dict, &pybwdt_locals_dict
-    );
-
diff --git a/ports/cc3200/mods/modmachine.c b/ports/cc3200/mods/modmachine.c
index bdf963c31..107efaef1 100644
--- a/ports/cc3200/mods/modmachine.c
+++ b/ports/cc3200/mods/modmachine.c
@@ -30,6 +30,7 @@
 
 #include "py/runtime.h"
 #include "py/mphal.h"
+#include "extmod/modmachine.h"
 #include "inc/hw_types.h"
 #include "inc/hw_gpio.h"
 #include "inc/hw_ints.h"
@@ -51,7 +52,6 @@
 #include "pybadc.h"
 #include "pybi2c.h"
 #include "pybsd.h"
-#include "pybwdt.h"
 #include "pybsleep.h"
 #include "pybspi.h"
 #include "pybtimer.h"
@@ -189,7 +189,7 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_SPI),                 MP_ROM_PTR(&pyb_spi_type) },
     { MP_ROM_QSTR(MP_QSTR_UART),                MP_ROM_PTR(&pyb_uart_type) },
     { MP_ROM_QSTR(MP_QSTR_Timer),               MP_ROM_PTR(&pyb_timer_type) },
-    { MP_ROM_QSTR(MP_QSTR_WDT),                 MP_ROM_PTR(&pyb_wdt_type) },
+    { MP_ROM_QSTR(MP_QSTR_WDT),                 MP_ROM_PTR(&machine_wdt_type) },
     { MP_ROM_QSTR(MP_QSTR_SD),                  MP_ROM_PTR(&pyb_sd_type) },
 
     // class constants
diff --git a/ports/cc3200/mods/pybwdt.h b/ports/cc3200/mods/pybwdt.h
index 275c49435..e106ae30e 100644
--- a/ports/cc3200/mods/pybwdt.h
+++ b/ports/cc3200/mods/pybwdt.h
@@ -26,9 +26,7 @@
 #ifndef MICROPY_INCLUDED_CC3200_MODS_PYBWDT_H
 #define MICROPY_INCLUDED_CC3200_MODS_PYBWDT_H
 
-#include "py/obj.h"
-
-extern const mp_obj_type_t pyb_wdt_type;
+#include <stdbool.h>
 
 void pybwdt_init0 (void);
 void pybwdt_srv_alive (void);
diff --git a/ports/cc3200/mpconfigport.h b/ports/cc3200/mpconfigport.h
index b6b412f17..6b2dc7ca0 100644
--- a/ports/cc3200/mpconfigport.h
+++ b/ports/cc3200/mpconfigport.h
@@ -120,6 +120,8 @@
 #define MICROPY_PY_TIME_GMTIME_LOCALTIME_MKTIME     (1)
 #define MICROPY_PY_TIME_TIME_TIME_NS                (1)
 #define MICROPY_PY_TIME_INCLUDEFILE                 "ports/cc3200/mods/modtime.c"
+#define MICROPY_PY_MACHINE_WDT                      (1)
+#define MICROPY_PY_MACHINE_WDT_INCLUDEFILE          "ports/cc3200/mods/machine_wdt.c"
 
 #define MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF      (1)
 #define MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE        (0)
diff --git a/ports/esp32/esp32_common.cmake b/ports/esp32/esp32_common.cmake
index f5219048f..e1dd546ea 100644
--- a/ports/esp32/esp32_common.cmake
+++ b/ports/esp32/esp32_common.cmake
@@ -86,7 +86,6 @@ list(APPEND MICROPY_SOURCE_PORT
     esp32_ulp.c
     modesp32.c
     machine_hw_spi.c
-    machine_wdt.c
     mpthreadport.c
     machine_rtc.c
     machine_sdcard.c
diff --git a/ports/esp32/machine_wdt.c b/ports/esp32/machine_wdt.c
index bf924c35e..cee761f26 100644
--- a/ports/esp32/machine_wdt.c
+++ b/ports/esp32/machine_wdt.c
@@ -25,16 +25,11 @@
  * THE SOFTWARE.
  */
 
-#include <string.h>
-
-#include "py/nlr.h"
-#include "py/obj.h"
-#include "py/runtime.h"
+// This file is never compiled standalone, it's included directly from
+// extmod/machine_wdt.c via MICROPY_PY_MACHINE_WDT_INCLUDEFILE.
 
 #include "esp_task_wdt.h"
 
-const mp_obj_type_t machine_wdt_type;
-
 typedef struct _machine_wdt_obj_t {
     mp_obj_base_t base;
     esp_task_wdt_user_handle_t twdt_user_handle;
@@ -44,25 +39,17 @@ STATIC machine_wdt_obj_t wdt_default = {
     {&machine_wdt_type}, 0
 };
 
-STATIC mp_obj_t machine_wdt_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
-    enum { ARG_id, ARG_timeout };
-    static const mp_arg_t allowed_args[] = {
-        { MP_QSTR_id, MP_ARG_INT, {.u_int = 0} },
-        { MP_QSTR_timeout, MP_ARG_INT, {.u_int = 5000} }
-    };
-    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
-    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
-
-    if (args[ARG_id].u_int != 0) {
+STATIC machine_wdt_obj_t *mp_machine_wdt_make_new_instance(mp_int_t id, mp_int_t timeout_ms) {
+    if (id != 0) {
         mp_raise_ValueError(NULL);
     }
 
-    if (args[ARG_timeout].u_int <= 0) {
+    if (timeout_ms <= 0) {
         mp_raise_ValueError(MP_ERROR_TEXT("WDT timeout too short"));
     }
 
     esp_task_wdt_config_t config = {
-        .timeout_ms = args[ARG_timeout].u_int,
+        .timeout_ms = timeout_ms,
         .idle_core_mask = 0,
         .trigger_panic = true,
     };
@@ -81,25 +68,10 @@ STATIC mp_obj_t machine_wdt_make_new(const mp_obj_type_t *type_in, size_t n_args
     return &wdt_default;
 }
 
-STATIC mp_obj_t machine_wdt_feed(mp_obj_t self_in) {
-    (void)self_in;
+STATIC void mp_machine_wdt_feed(machine_wdt_obj_t *self) {
+    (void)self;
     mp_int_t rs_code = esp_task_wdt_reset_user(wdt_default.twdt_user_handle);
     if (rs_code != ESP_OK) {
         mp_raise_OSError(rs_code);
     }
-    return mp_const_none;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_wdt_feed_obj, machine_wdt_feed);
-
-STATIC const mp_rom_map_elem_t machine_wdt_locals_dict_table[] = {
-    { MP_ROM_QSTR(MP_QSTR_feed), MP_ROM_PTR(&machine_wdt_feed_obj) },
-};
-STATIC MP_DEFINE_CONST_DICT(machine_wdt_locals_dict, machine_wdt_locals_dict_table);
-
-MP_DEFINE_CONST_OBJ_TYPE(
-    machine_wdt_type,
-    MP_QSTR_WDT,
-    MP_TYPE_FLAG_NONE,
-    make_new, machine_wdt_make_new,
-    locals_dict, &machine_wdt_locals_dict
-    );
diff --git a/ports/esp32/modmachine.c b/ports/esp32/modmachine.c
index 31fa589ae..f8567973b 100644
--- a/ports/esp32/modmachine.c
+++ b/ports/esp32/modmachine.c
@@ -47,6 +47,7 @@
 #include "extmod/machine_pwm.h"
 #include "extmod/machine_i2c.h"
 #include "extmod/machine_spi.h"
+#include "extmod/modmachine.h"
 #include "modmachine.h"
 #include "machine_rtc.h"
 
@@ -297,7 +298,9 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_dht_readinto), MP_ROM_PTR(&dht_readinto_obj) },
 
     { MP_ROM_QSTR(MP_QSTR_Timer), MP_ROM_PTR(&machine_timer_type) },
+    #if MICROPY_PY_MACHINE_WDT
     { MP_ROM_QSTR(MP_QSTR_WDT), MP_ROM_PTR(&machine_wdt_type) },
+    #endif
     #if MICROPY_HW_ENABLE_SDCARD
     { MP_ROM_QSTR(MP_QSTR_SDCard), MP_ROM_PTR(&machine_sdcard_type) },
     #endif
diff --git a/ports/esp32/modmachine.h b/ports/esp32/modmachine.h
index 24417f610..24f27101a 100644
--- a/ports/esp32/modmachine.h
+++ b/ports/esp32/modmachine.h
@@ -10,7 +10,6 @@ typedef enum {
 } wake_type_t;
 
 extern const mp_obj_type_t machine_timer_type;
-extern const mp_obj_type_t machine_wdt_type;
 extern const mp_obj_type_t machine_pin_type;
 extern const mp_obj_type_t machine_touchpad_type;
 extern const mp_obj_type_t machine_adc_type;
diff --git a/ports/esp32/mpconfigport.h b/ports/esp32/mpconfigport.h
index 04a745262..5d39323c5 100644
--- a/ports/esp32/mpconfigport.h
+++ b/ports/esp32/mpconfigport.h
@@ -115,6 +115,8 @@
 #ifndef MICROPY_PY_MACHINE_I2S
 #define MICROPY_PY_MACHINE_I2S              (1)
 #endif
+#define MICROPY_PY_MACHINE_WDT              (1)
+#define MICROPY_PY_MACHINE_WDT_INCLUDEFILE  "ports/esp32/machine_wdt.c"
 #define MICROPY_PY_NETWORK (1)
 #ifndef MICROPY_PY_NETWORK_HOSTNAME_DEFAULT
 #if CONFIG_IDF_TARGET_ESP32
diff --git a/ports/esp8266/Makefile b/ports/esp8266/Makefile
index 75b407633..5982987d7 100644
--- a/ports/esp8266/Makefile
+++ b/ports/esp8266/Makefile
@@ -116,7 +116,6 @@ SRC_C = \
 	machine_rtc.c \
 	machine_adc.c \
 	machine_uart.c \
-	machine_wdt.c \
 	machine_hspi.c \
 	modesp.c \
 	network_wlan.c \
diff --git a/ports/esp8266/machine_wdt.c b/ports/esp8266/machine_wdt.c
index 39a5d5111..074ee5659 100644
--- a/ports/esp8266/machine_wdt.c
+++ b/ports/esp8266/machine_wdt.c
@@ -24,27 +24,22 @@
  * THE SOFTWARE.
  */
 
-#include <string.h>
+// This file is never compiled standalone, it's included directly from
+// extmod/machine_wdt.c via MICROPY_PY_MACHINE_WDT_INCLUDEFILE.
 
-#include "py/runtime.h"
 #include "user_interface.h"
-#include "etshal.h"
 #include "ets_alt_task.h"
 
-const mp_obj_type_t esp_wdt_type;
-
 typedef struct _machine_wdt_obj_t {
     mp_obj_base_t base;
 } machine_wdt_obj_t;
 
-STATIC machine_wdt_obj_t wdt_default = {{&esp_wdt_type}};
-
-STATIC mp_obj_t machine_wdt_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
-    mp_arg_check_num(n_args, n_kw, 0, 1, false);
+STATIC machine_wdt_obj_t wdt_default = {{&machine_wdt_type}};
 
-    mp_int_t id = 0;
-    if (n_args > 0) {
-        id = mp_obj_get_int(args[0]);
+STATIC machine_wdt_obj_t *mp_machine_wdt_make_new_instance(mp_int_t id, mp_int_t timeout_ms) {
+    // The timeout on ESP8266 is fixed, so raise an exception if the argument is not the default.
+    if (timeout_ms != 5000) {
+        mp_raise_ValueError(NULL);
     }
 
     switch (id) {
@@ -57,22 +52,7 @@ STATIC mp_obj_t machine_wdt_make_new(const mp_obj_type_t *type_in, size_t n_args
     }
 }
 
-STATIC mp_obj_t machine_wdt_feed(mp_obj_t self_in) {
-    (void)self_in;
+STATIC void mp_machine_wdt_feed(machine_wdt_obj_t *self) {
+    (void)self;
     system_soft_wdt_feed();
-    return mp_const_none;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_wdt_feed_obj, machine_wdt_feed);
-
-STATIC const mp_rom_map_elem_t machine_wdt_locals_dict_table[] = {
-    { MP_ROM_QSTR(MP_QSTR_feed), MP_ROM_PTR(&machine_wdt_feed_obj) },
-};
-STATIC MP_DEFINE_CONST_DICT(machine_wdt_locals_dict, machine_wdt_locals_dict_table);
-
-MP_DEFINE_CONST_OBJ_TYPE(
-    esp_wdt_type,
-    MP_QSTR_WDT,
-    MP_TYPE_FLAG_NONE,
-    make_new, machine_wdt_make_new,
-    locals_dict, &machine_wdt_locals_dict
-    );
diff --git a/ports/esp8266/modmachine.c b/ports/esp8266/modmachine.c
index 64346b4de..eee5f3c68 100644
--- a/ports/esp8266/modmachine.c
+++ b/ports/esp8266/modmachine.c
@@ -43,6 +43,7 @@
 #include "extmod/machine_pwm.h"
 #include "extmod/machine_i2c.h"
 #include "extmod/machine_spi.h"
+#include "extmod/modmachine.h"
 #include "modmachine.h"
 
 #include "xtirq.h"
@@ -58,8 +59,6 @@
 // #define MACHINE_WAKE_SLEEP (0x02)
 #define MACHINE_WAKE_DEEPSLEEP (0x04)
 
-extern const mp_obj_type_t esp_wdt_type;
-
 STATIC mp_obj_t machine_freq(size_t n_args, const mp_obj_t *args) {
     if (n_args == 0) {
         // get
@@ -423,7 +422,9 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
 
     { MP_ROM_QSTR(MP_QSTR_RTC), MP_ROM_PTR(&pyb_rtc_type) },
     { MP_ROM_QSTR(MP_QSTR_Timer), MP_ROM_PTR(&esp_timer_type) },
-    { MP_ROM_QSTR(MP_QSTR_WDT), MP_ROM_PTR(&esp_wdt_type) },
+    #if MICROPY_PY_MACHINE_WDT
+    { MP_ROM_QSTR(MP_QSTR_WDT), MP_ROM_PTR(&machine_wdt_type) },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_Pin), MP_ROM_PTR(&pyb_pin_type) },
     { MP_ROM_QSTR(MP_QSTR_Signal), MP_ROM_PTR(&machine_signal_type) },
     { MP_ROM_QSTR(MP_QSTR_PWM), MP_ROM_PTR(&machine_pwm_type) },
diff --git a/ports/esp8266/mpconfigport.h b/ports/esp8266/mpconfigport.h
index 18b2e47e2..2a51f8bcb 100644
--- a/ports/esp8266/mpconfigport.h
+++ b/ports/esp8266/mpconfigport.h
@@ -71,6 +71,8 @@
 #define MICROPY_PY_MACHINE_SOFTI2C  (1)
 #define MICROPY_PY_MACHINE_SPI      (1)
 #define MICROPY_PY_MACHINE_SOFTSPI  (1)
+#define MICROPY_PY_MACHINE_WDT      (1)
+#define MICROPY_PY_MACHINE_WDT_INCLUDEFILE "ports/esp8266/machine_wdt.c"
 #define MICROPY_PY_NETWORK (1)
 #ifndef MICROPY_PY_NETWORK_HOSTNAME_DEFAULT
 #define MICROPY_PY_NETWORK_HOSTNAME_DEFAULT "mpy-esp8266"
diff --git a/ports/mimxrt/Makefile b/ports/mimxrt/Makefile
index 3521f9228..d29b38e04 100644
--- a/ports/mimxrt/Makefile
+++ b/ports/mimxrt/Makefile
@@ -205,7 +205,6 @@ SRC_C += \
 	machine_sdcard.c \
 	machine_spi.c \
 	machine_uart.c \
-	machine_wdt.c \
 	main.c \
 	mbedtls/mbedtls_port.c \
 	mimxrt_flash.c \
diff --git a/ports/mimxrt/machine_wdt.c b/ports/mimxrt/machine_wdt.c
index f5f14f9ef..176e114f7 100644
--- a/ports/mimxrt/machine_wdt.c
+++ b/ports/mimxrt/machine_wdt.c
@@ -24,8 +24,8 @@
  * THE SOFTWARE.
  */
 
-#include "py/runtime.h"
-#include "modmachine.h"
+// This file is never compiled standalone, it's included directly from
+// extmod/machine_wdt.c via MICROPY_PY_MACHINE_WDT_INCLUDEFILE.
 
 #include "fsl_wdog.h"
 
@@ -38,19 +38,8 @@ typedef struct _machine_wdt_obj_t {
 
 STATIC const machine_wdt_obj_t machine_wdt = {{&machine_wdt_type}};
 
-STATIC mp_obj_t machine_wdt_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
-    enum { ARG_id, ARG_timeout };
-    static const mp_arg_t allowed_args[] = {
-        { MP_QSTR_id, MP_ARG_INT, {.u_int = 0} },
-        { MP_QSTR_timeout, MP_ARG_INT, {.u_int = 5000} },
-    };
-
-    // Parse the arguments.
-    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
-    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
-
+STATIC machine_wdt_obj_t *mp_machine_wdt_make_new_instance(mp_int_t id, mp_int_t timeout_ms) {
     // Verify the WDT id.
-    mp_int_t id = args[ARG_id].u_int;
     if (id != 0) {
         mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("WDT(%d) doesn't exist"), id);
     }
@@ -58,51 +47,33 @@ STATIC mp_obj_t machine_wdt_make_new(const mp_obj_type_t *type, size_t n_args, s
     // Start the watchdog (timeout is in milliseconds).
     wdog_config_t config;
     WDOG_GetDefaultConfig(&config);
-    uint32_t timeout = args[ARG_timeout].u_int;
     // confine to the valid range
-    if (timeout < MIN_TIMEOUT) {
-        timeout = MIN_TIMEOUT;
-    } else if (timeout > MAX_TIMEOUT) {
-        timeout = MAX_TIMEOUT;
+    if (timeout_ms < MIN_TIMEOUT) {
+        timeout_ms = MIN_TIMEOUT;
+    } else if (timeout_ms > MAX_TIMEOUT) {
+        timeout_ms = MAX_TIMEOUT;
     }
-    config.timeoutValue = (timeout / 500) - 1;
+    config.timeoutValue = (timeout_ms / 500) - 1;
     WDOG_Init(WDOG1, &config);
 
-    return MP_OBJ_FROM_PTR(&machine_wdt);
+    return (machine_wdt_obj_t *)&machine_wdt;
 }
 
-STATIC mp_obj_t machine_wdt_feed(mp_obj_t self_in) {
-    (void)self_in;
+STATIC void mp_machine_wdt_feed(machine_wdt_obj_t *self) {
+    (void)self;
     WDOG_Refresh(WDOG1);
-    return mp_const_none;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_wdt_feed_obj, machine_wdt_feed);
 
-STATIC mp_obj_t machine_wdt_timeout_ms(mp_obj_t self_in, mp_obj_t timout_in) {
-    uint32_t timeout = mp_obj_get_int(timout_in);
+STATIC void mp_machine_wdt_timeout_ms_set(machine_wdt_obj_t *self, mp_int_t timeout_ms) {
+    (void)self;
+
     // confine to the valid range
-    if (timeout < MIN_TIMEOUT) {
-        timeout = MIN_TIMEOUT;
-    } else if (timeout > MAX_TIMEOUT) {
-        timeout = MAX_TIMEOUT;
+    if (timeout_ms < MIN_TIMEOUT) {
+        timeout_ms = MIN_TIMEOUT;
+    } else if (timeout_ms > MAX_TIMEOUT) {
+        timeout_ms = MAX_TIMEOUT;
     }
-    timeout = (timeout / 500) - 1;
+    uint32_t timeout = (timeout_ms / 500) - 1;
     WDOG_SetTimeoutValue(WDOG1, (uint16_t)timeout);
     WDOG_Refresh(WDOG1);
-    return mp_const_none;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_2(machine_wdt_timeout_ms_obj, machine_wdt_timeout_ms);
-
-STATIC const mp_rom_map_elem_t machine_wdt_locals_dict_table[] = {
-    { MP_ROM_QSTR(MP_QSTR_feed), MP_ROM_PTR(&machine_wdt_feed_obj) },
-    { MP_ROM_QSTR(MP_QSTR_timeout_ms), MP_ROM_PTR(&machine_wdt_timeout_ms_obj) },
-};
-STATIC MP_DEFINE_CONST_DICT(machine_wdt_locals_dict, machine_wdt_locals_dict_table);
-
-MP_DEFINE_CONST_OBJ_TYPE(
-    machine_wdt_type,
-    MP_QSTR_WDT,
-    MP_TYPE_FLAG_NONE,
-    make_new, machine_wdt_make_new,
-    locals_dict, &machine_wdt_locals_dict
-    );
diff --git a/ports/mimxrt/modmachine.c b/ports/mimxrt/modmachine.c
index 16eae2202..c2f3559cf 100644
--- a/ports/mimxrt/modmachine.c
+++ b/ports/mimxrt/modmachine.c
@@ -33,6 +33,7 @@
 #include "extmod/machine_pulse.h"
 #include "extmod/machine_signal.h"
 #include "extmod/machine_spi.h"
+#include "extmod/modmachine.h"
 #include "shared/runtime/pyexec.h"
 #include "led.h"
 #include "pin.h"
@@ -204,7 +205,9 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     #endif
     { MP_ROM_QSTR(MP_QSTR_SPI),                 MP_ROM_PTR(&machine_spi_type) },
     { MP_ROM_QSTR(MP_QSTR_UART),                MP_ROM_PTR(&machine_uart_type) },
+    #if MICROPY_PY_MACHINE_WDT
     { MP_ROM_QSTR(MP_QSTR_WDT),                 MP_ROM_PTR(&machine_wdt_type) },
+    #endif
 
     { MP_ROM_QSTR(MP_QSTR_idle),                MP_ROM_PTR(&machine_idle_obj) },
     { MP_ROM_QSTR(MP_QSTR_deepsleep),           MP_ROM_PTR(&machine_deepsleep_obj) },
diff --git a/ports/mimxrt/modmachine.h b/ports/mimxrt/modmachine.h
index 478b1c773..cf40505ea 100644
--- a/ports/mimxrt/modmachine.h
+++ b/ports/mimxrt/modmachine.h
@@ -38,7 +38,6 @@ extern const mp_obj_type_t machine_sdcard_type;
 extern const mp_obj_type_t machine_spi_type;
 extern const mp_obj_type_t machine_timer_type;
 extern const mp_obj_type_t machine_uart_type;
-extern const mp_obj_type_t machine_wdt_type;
 
 void machine_adc_init(void);
 void machine_pin_irq_deinit(void);
diff --git a/ports/mimxrt/mpconfigport.h b/ports/mimxrt/mpconfigport.h
index feb6cb266..1eb3b1711 100644
--- a/ports/mimxrt/mpconfigport.h
+++ b/ports/mimxrt/mpconfigport.h
@@ -94,6 +94,9 @@ uint32_t trng_random_u32(void);
 #define MICROPY_PY_MACHINE_SPI              (1)
 #define MICROPY_PY_MACHINE_SOFTSPI          (1)
 #define MICROPY_PY_MACHINE_TIMER            (1)
+#define MICROPY_PY_MACHINE_WDT              (1)
+#define MICROPY_PY_MACHINE_WDT_INCLUDEFILE  "ports/mimxrt/machine_wdt.c"
+#define MICROPY_PY_MACHINE_WDT_TIMEOUT_MS   (1)
 #define MICROPY_SOFT_TIMER_TICKS_MS         systick_ms
 #define MICROPY_PY_ONEWIRE                  (1)
 
diff --git a/ports/renesas-ra/modmachine.h b/ports/renesas-ra/modmachine.h
index 5dbda6bda..ec494b798 100644
--- a/ports/renesas-ra/modmachine.h
+++ b/ports/renesas-ra/modmachine.h
@@ -30,7 +30,6 @@
 #include "py/obj.h"
 
 extern const mp_obj_type_t machine_timer_type;
-extern const mp_obj_type_t machine_wdt_type;
 extern const mp_obj_type_t machine_pin_type;
 extern const mp_obj_type_t machine_touchpad_type;
 extern const mp_obj_type_t machine_adc_type;
diff --git a/ports/rp2/CMakeLists.txt b/ports/rp2/CMakeLists.txt
index fae4cda75..b8cf4d7be 100644
--- a/ports/rp2/CMakeLists.txt
+++ b/ports/rp2/CMakeLists.txt
@@ -126,7 +126,6 @@ set(MICROPY_SOURCE_PORT
     machine_spi.c
     machine_timer.c
     machine_uart.c
-    machine_wdt.c
     main.c
     modmachine.c
     modrp2.c
diff --git a/ports/rp2/machine_wdt.c b/ports/rp2/machine_wdt.c
index 6574a6180..58c372176 100644
--- a/ports/rp2/machine_wdt.c
+++ b/ports/rp2/machine_wdt.c
@@ -24,8 +24,8 @@
  * THE SOFTWARE.
  */
 
-#include "py/runtime.h"
-#include "modmachine.h"
+// This file is never compiled standalone, it's included directly from
+// extmod/machine_wdt.c via MICROPY_PY_MACHINE_WDT_INCLUDEFILE.
 
 #include "hardware/watchdog.h"
 
@@ -38,49 +38,23 @@ typedef struct _machine_wdt_obj_t {
 
 STATIC const machine_wdt_obj_t machine_wdt = {{&machine_wdt_type}};
 
-STATIC mp_obj_t machine_wdt_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
-    enum { ARG_id, ARG_timeout };
-    static const mp_arg_t allowed_args[] = {
-        { MP_QSTR_id, MP_ARG_INT, {.u_int = 0} },
-        { MP_QSTR_timeout, MP_ARG_INT, {.u_int = 5000} },
-    };
-
-    // Parse the arguments.
-    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
-    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
-
+STATIC machine_wdt_obj_t *mp_machine_wdt_make_new_instance(mp_int_t id, mp_int_t timeout_ms) {
     // Verify the WDT id.
-    mp_int_t id = args[ARG_id].u_int;
     if (id != 0) {
         mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("WDT(%d) doesn't exist"), id);
     }
 
     // Start the watchdog (timeout is in milliseconds).
-    uint32_t timeout = args[ARG_timeout].u_int;
+    uint32_t timeout = timeout_ms;
     if (timeout > WDT_TIMEOUT_MAX) {
         mp_raise_ValueError(MP_ERROR_TEXT("timeout exceeds " MP_STRINGIFY(WDT_TIMEOUT_MAX)));
     }
     watchdog_enable(timeout, false);
 
-    return MP_OBJ_FROM_PTR(&machine_wdt);
+    return (machine_wdt_obj_t *)&machine_wdt;
 }
 
-STATIC mp_obj_t machine_wdt_feed(mp_obj_t self_in) {
-    (void)self_in;
+STATIC void mp_machine_wdt_feed(machine_wdt_obj_t *self) {
+    (void)self;
     watchdog_update();
-    return mp_const_none;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_wdt_feed_obj, machine_wdt_feed);
-
-STATIC const mp_rom_map_elem_t machine_wdt_locals_dict_table[] = {
-    { MP_ROM_QSTR(MP_QSTR_feed), MP_ROM_PTR(&machine_wdt_feed_obj) },
-};
-STATIC MP_DEFINE_CONST_DICT(machine_wdt_locals_dict, machine_wdt_locals_dict_table);
-
-MP_DEFINE_CONST_OBJ_TYPE(
-    machine_wdt_type,
-    MP_QSTR_WDT,
-    MP_TYPE_FLAG_NONE,
-    make_new, machine_wdt_make_new,
-    locals_dict, &machine_wdt_locals_dict
-    );
diff --git a/ports/rp2/modmachine.c b/ports/rp2/modmachine.c
index 35c938b54..eedeca1e3 100644
--- a/ports/rp2/modmachine.c
+++ b/ports/rp2/modmachine.c
@@ -35,6 +35,7 @@
 #include "extmod/machine_pwm.h"
 #include "extmod/machine_signal.h"
 #include "extmod/machine_spi.h"
+#include "extmod/modmachine.h"
 
 #include "modmachine.h"
 #include "uart.h"
@@ -266,7 +267,9 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_SoftSPI),             MP_ROM_PTR(&mp_machine_soft_spi_type) },
     { MP_ROM_QSTR(MP_QSTR_Timer),               MP_ROM_PTR(&machine_timer_type) },
     { MP_ROM_QSTR(MP_QSTR_UART),                MP_ROM_PTR(&machine_uart_type) },
+    #if MICROPY_PY_MACHINE_WDT
     { MP_ROM_QSTR(MP_QSTR_WDT),                 MP_ROM_PTR(&machine_wdt_type) },
+    #endif
 
     { MP_ROM_QSTR(MP_QSTR_PWRON_RESET),         MP_ROM_INT(RP2_RESET_PWRON) },
     { MP_ROM_QSTR(MP_QSTR_WDT_RESET),           MP_ROM_INT(RP2_RESET_WDT) },
diff --git a/ports/rp2/modmachine.h b/ports/rp2/modmachine.h
index 45ccd49e8..559fb3481 100644
--- a/ports/rp2/modmachine.h
+++ b/ports/rp2/modmachine.h
@@ -11,7 +11,6 @@ extern const mp_obj_type_t machine_rtc_type;
 extern const mp_obj_type_t machine_spi_type;
 extern const mp_obj_type_t machine_timer_type;
 extern const mp_obj_type_t machine_uart_type;
-extern const mp_obj_type_t machine_wdt_type;
 
 void machine_pin_init(void);
 void machine_pin_deinit(void);
diff --git a/ports/rp2/mpconfigport.h b/ports/rp2/mpconfigport.h
index 056e2df4f..bf43b5ce7 100644
--- a/ports/rp2/mpconfigport.h
+++ b/ports/rp2/mpconfigport.h
@@ -122,6 +122,8 @@
 #define MICROPY_PY_MACHINE_SPI_MSB              (SPI_MSB_FIRST)
 #define MICROPY_PY_MACHINE_SPI_LSB              (SPI_LSB_FIRST)
 #define MICROPY_PY_MACHINE_SOFTSPI              (1)
+#define MICROPY_PY_MACHINE_WDT                  (1)
+#define MICROPY_PY_MACHINE_WDT_INCLUDEFILE      "ports/rp2/machine_wdt.c"
 #define MICROPY_PY_ONEWIRE                      (1)
 #define MICROPY_VFS                             (1)
 #define MICROPY_VFS_LFS2                        (1)
diff --git a/ports/samd/Makefile b/ports/samd/Makefile
index 6dd71bd93..8e4327073 100644
--- a/ports/samd/Makefile
+++ b/ports/samd/Makefile
@@ -104,7 +104,6 @@ SRC_C += \
 	machine_rtc.c \
 	machine_spi.c \
 	machine_uart.c \
-	machine_wdt.c \
 	main.c \
 	modmachine.c \
 	modsamd.c \
diff --git a/ports/samd/machine_wdt.c b/ports/samd/machine_wdt.c
index d7dcfcf54..d6fadfd12 100644
--- a/ports/samd/machine_wdt.c
+++ b/ports/samd/machine_wdt.c
@@ -24,8 +24,8 @@
  * THE SOFTWARE.
  */
 
-#include "py/runtime.h"
-#include "modmachine.h"
+// This file is never compiled standalone, it's included directly from
+// extmod/machine_wdt.c via MICROPY_PY_MACHINE_WDT_INCLUDEFILE.
 
 #include "sam.h"
 
@@ -76,27 +76,15 @@ STATIC void set_timeout(uint32_t timeout) {
     #endif
 }
 
-STATIC mp_obj_t machine_wdt_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
-    enum { ARG_id, ARG_timeout, ARG_lock };
-    static const mp_arg_t allowed_args[] = {
-        { MP_QSTR_id, MP_ARG_INT, {.u_int = 0} },
-        { MP_QSTR_timeout, MP_ARG_INT, {.u_int = 5000} },
-    };
-
-    // Parse the arguments.
-    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
-    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
-
+STATIC machine_wdt_obj_t *mp_machine_wdt_make_new_instance(mp_int_t id, mp_int_t timeout_ms) {
     #if defined(MCU_SAMD51)
     // Verify the WDT id. SAMD51 only, saving a few bytes for SAMD21
-    mp_int_t id = args[ARG_id].u_int;
     if (id != 0) {
         mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("WDT(%d) doesn't exist"), id);
     }
     #endif
 
     // Start the watchdog (timeout is in milliseconds).
-    uint32_t timeout = args[ARG_timeout].u_int;
     // Configure the WDT
     #if defined(MCU_SAMD21)
 
@@ -112,37 +100,17 @@ STATIC mp_obj_t machine_wdt_make_new(const mp_obj_type_t *type, size_t n_args, s
 
     #endif
 
-    set_timeout(timeout);
+    set_timeout(timeout_ms);
 
-    return MP_OBJ_FROM_PTR(&machine_wdt);
+    return (machine_wdt_obj_t *)&machine_wdt;
 }
 
-STATIC mp_obj_t machine_wdt_feed(mp_obj_t self_in) {
-    (void)self_in;
+STATIC void mp_machine_wdt_feed(machine_wdt_obj_t *self) {
+    (void)self;
     WDT->CLEAR.reg = 0xa5;
-    return mp_const_none;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_wdt_feed_obj, machine_wdt_feed);
-
-STATIC mp_obj_t machine_wdt_timeout_ms(mp_obj_t self_in, mp_obj_t timout_in) {
-    uint32_t timeout = mp_obj_get_int(timout_in);
-
-    set_timeout(timeout);
 
-    return mp_const_none;
+STATIC void mp_machine_wdt_timeout_ms_set(machine_wdt_obj_t *self, mp_int_t timeout_ms) {
+    (void)self;
+    set_timeout(timeout_ms);
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_2(machine_wdt_timeout_ms_obj, machine_wdt_timeout_ms);
-
-STATIC const mp_rom_map_elem_t machine_wdt_locals_dict_table[] = {
-    { MP_ROM_QSTR(MP_QSTR_feed), MP_ROM_PTR(&machine_wdt_feed_obj) },
-    { MP_ROM_QSTR(MP_QSTR_timeout_ms), MP_ROM_PTR(&machine_wdt_timeout_ms_obj) },
-};
-STATIC MP_DEFINE_CONST_DICT(machine_wdt_locals_dict, machine_wdt_locals_dict_table);
-
-MP_DEFINE_CONST_OBJ_TYPE(
-    machine_wdt_type,
-    MP_QSTR_WDT,
-    MP_TYPE_FLAG_NONE,
-    make_new, machine_wdt_make_new,
-    locals_dict, &machine_wdt_locals_dict
-    );
diff --git a/ports/samd/modmachine.c b/ports/samd/modmachine.c
index 9d5b7c2e2..97718401a 100644
--- a/ports/samd/modmachine.c
+++ b/ports/samd/modmachine.c
@@ -31,6 +31,7 @@
 #include "extmod/machine_i2c.h"
 #include "extmod/machine_signal.h"
 #include "extmod/machine_spi.h"
+#include "extmod/modmachine.h"
 #include "drivers/dht/dht.h"
 #include "shared/runtime/pyexec.h"
 #include "modmachine.h"
@@ -261,7 +262,9 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     #if MICROPY_PY_MACHINE_UART
     { MP_ROM_QSTR(MP_QSTR_UART),                MP_ROM_PTR(&machine_uart_type) },
     #endif
+    #if MICROPY_PY_MACHINE_WDT
     { MP_ROM_QSTR(MP_QSTR_WDT),                 MP_ROM_PTR(&machine_wdt_type) },
+    #endif
     #if MICROPY_PY_MACHINE_RTC
     { MP_ROM_QSTR(MP_QSTR_RTC),                 MP_ROM_PTR(&machine_rtc_type) },
     #endif
diff --git a/ports/samd/modmachine.h b/ports/samd/modmachine.h
index b3ba44039..d62b14a0a 100644
--- a/ports/samd/modmachine.h
+++ b/ports/samd/modmachine.h
@@ -49,7 +49,6 @@ extern const mp_obj_type_t machine_timer_type;
 #if MICROPY_PY_MACHINE_UART
 extern const mp_obj_type_t machine_uart_type;
 #endif
-extern const mp_obj_type_t machine_wdt_type;
 #if MICROPY_PY_MACHINE_RTC
 extern const mp_obj_type_t machine_rtc_type;
 #endif
diff --git a/ports/samd/mpconfigport.h b/ports/samd/mpconfigport.h
index 011119fd1..3505d8db1 100644
--- a/ports/samd/mpconfigport.h
+++ b/ports/samd/mpconfigport.h
@@ -127,6 +127,9 @@
 #endif
 #define MICROPY_PY_MACHINE_PIN_MAKE_NEW     mp_pin_make_new
 #define MICROPY_PY_MACHINE_DHT_READINTO     (1)
+#define MICROPY_PY_MACHINE_WDT              (1)
+#define MICROPY_PY_MACHINE_WDT_INCLUDEFILE  "ports/samd/machine_wdt.c"
+#define MICROPY_PY_MACHINE_WDT_TIMEOUT_MS   (1)
 #define MICROPY_PY_ONEWIRE                  (1)
 #define MICROPY_PY_PLATFORM                 (1)
 #define MICROPY_PLATFORM_VERSION            "ASF4"
diff --git a/ports/stm32/Makefile b/ports/stm32/Makefile
index dcfc8dfd5..589ef4cdb 100644
--- a/ports/stm32/Makefile
+++ b/ports/stm32/Makefile
@@ -329,7 +329,6 @@ SRC_C += \
 	fdcan.c \
 	pyb_can.c \
 	usb.c \
-	wdt.c \
 	eth.c \
 	gccollect.c \
 	help.c \
diff --git a/ports/stm32/wdt.c b/ports/stm32/machine_wdt.c
index e541e4d36..e0605751d 100644
--- a/ports/stm32/wdt.c
+++ b/ports/stm32/machine_wdt.c
@@ -3,7 +3,7 @@
  *
  * The MIT License (MIT)
  *
- * Copyright (c) 2016 Damien P. George
+ * Copyright (c) 2016-2023 Damien P. George
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -24,40 +24,28 @@
  * THE SOFTWARE.
  */
 
-#include <stdio.h>
+// This file is never compiled standalone, it's included directly from
+// extmod/machine_wdt.c via MICROPY_PY_MACHINE_WDT_INCLUDEFILE.
 
-#include "py/runtime.h"
-#include "wdt.h"
+#include "py/mphal.h"
 
 #if defined(STM32H7)
 #define IWDG (IWDG1)
 #endif
 
-typedef struct _pyb_wdt_obj_t {
+typedef struct _machine_wdt_obj_t {
     mp_obj_base_t base;
-} pyb_wdt_obj_t;
+} machine_wdt_obj_t;
 
-STATIC const pyb_wdt_obj_t pyb_wdt = {{&pyb_wdt_type}};
+STATIC const machine_wdt_obj_t machine_wdt = {{&machine_wdt_type}};
 
-STATIC mp_obj_t pyb_wdt_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
-    // parse arguments
-    enum { ARG_id, ARG_timeout };
-    static const mp_arg_t allowed_args[] = {
-        { MP_QSTR_id, MP_ARG_INT, {.u_int = 0} },
-        { MP_QSTR_timeout, MP_ARG_INT, {.u_int = 5000} },
-    };
-    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
-    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
-
-    mp_int_t id = args[ARG_id].u_int;
+STATIC machine_wdt_obj_t *mp_machine_wdt_make_new_instance(mp_int_t id, mp_int_t timeout_ms) {
     if (id != 0) {
         mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("WDT(%d) doesn't exist"), id);
     }
 
-    // timeout is in milliseconds
-    mp_int_t timeout = args[ARG_timeout].u_int;
-
     // compute prescaler
+    int32_t timeout = timeout_ms;
     uint32_t prescaler;
     for (prescaler = 0; prescaler < 6 && timeout >= 512; ++prescaler, timeout /= 2) {
     }
@@ -86,26 +74,10 @@ STATIC mp_obj_t pyb_wdt_make_new(const mp_obj_type_t *type, size_t n_args, size_
     // start the watch dog
     IWDG->KR = 0xcccc;
 
-    return MP_OBJ_FROM_PTR(&pyb_wdt);
+    return (machine_wdt_obj_t *)&machine_wdt;
 }
 
-STATIC mp_obj_t pyb_wdt_feed(mp_obj_t self_in) {
-    (void)self_in;
+STATIC void mp_machine_wdt_feed(machine_wdt_obj_t *self) {
+    (void)self;
     IWDG->KR = 0xaaaa;
-    return mp_const_none;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_wdt_feed_obj, pyb_wdt_feed);
-
-STATIC const mp_rom_map_elem_t pyb_wdt_locals_dict_table[] = {
-    { MP_ROM_QSTR(MP_QSTR_feed), MP_ROM_PTR(&pyb_wdt_feed_obj) },
-};
-
-STATIC MP_DEFINE_CONST_DICT(pyb_wdt_locals_dict, pyb_wdt_locals_dict_table);
-
-MP_DEFINE_CONST_OBJ_TYPE(
-    pyb_wdt_type,
-    MP_QSTR_WDT,
-    MP_TYPE_FLAG_NONE,
-    make_new, pyb_wdt_make_new,
-    locals_dict, &pyb_wdt_locals_dict
-    );
diff --git a/ports/stm32/modmachine.c b/ports/stm32/modmachine.c
index 69fe8f4f5..926dc3041 100644
--- a/ports/stm32/modmachine.c
+++ b/ports/stm32/modmachine.c
@@ -38,6 +38,7 @@
 #include "extmod/machine_pulse.h"
 #include "extmod/machine_i2c.h"
 #include "extmod/machine_spi.h"
+#include "extmod/modmachine.h"
 #include "shared/runtime/pyexec.h"
 #include "lib/oofatfs/ff.h"
 #include "extmod/vfs.h"
@@ -56,7 +57,6 @@
 #include "i2c.h"
 #include "spi.h"
 #include "uart.h"
-#include "wdt.h"
 
 #if defined(STM32G0)
 // G0 has BOR and POR combined
@@ -447,7 +447,9 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_I2S),                 MP_ROM_PTR(&machine_i2s_type) },
     #endif
     { MP_ROM_QSTR(MP_QSTR_UART),                MP_ROM_PTR(&pyb_uart_type) },
-    { MP_ROM_QSTR(MP_QSTR_WDT),                 MP_ROM_PTR(&pyb_wdt_type) },
+    #if MICROPY_PY_MACHINE_WDT
+    { MP_ROM_QSTR(MP_QSTR_WDT),                 MP_ROM_PTR(&machine_wdt_type) },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_Timer),               MP_ROM_PTR(&machine_timer_type) },
     #if 0
     { MP_ROM_QSTR(MP_QSTR_HeartBeat),           MP_ROM_PTR(&pyb_heartbeat_type) },
diff --git a/ports/stm32/mpconfigport.h b/ports/stm32/mpconfigport.h
index 2d2d81486..0e9df54ff 100644
--- a/ports/stm32/mpconfigport.h
+++ b/ports/stm32/mpconfigport.h
@@ -122,6 +122,8 @@
 #define MICROPY_PY_MACHINE_SPI_LSB  (SPI_FIRSTBIT_LSB)
 #define MICROPY_PY_MACHINE_SOFTSPI  (1)
 #define MICROPY_PY_MACHINE_TIMER    (1)
+#define MICROPY_PY_MACHINE_WDT      (1)
+#define MICROPY_PY_MACHINE_WDT_INCLUDEFILE "ports/stm32/machine_wdt.c"
 #endif
 #define MICROPY_HW_SOFTSPI_MIN_DELAY (0)
 #define MICROPY_HW_SOFTSPI_MAX_BAUDRATE (HAL_RCC_GetSysClockFreq() / 48)