extmod/machine_i2c_target: Add new machine.I2CTarget class.

This commit implements a generic I2C target/peripheral/"slave" device,
called `machine.I2CTarget`.  It can work in two separate modes:

- A general device with interrupts/events/callbacks for low-level I2C
  operations like address match, read request and stop.

- A memory device that allows reading/writing a specific region of memory
  (or "registers") on the target I2C device.

To make a memory device is very simple:

    from machine import I2CTarget

    mem = bytearray(8)
    i2c = I2CTarget(addr=67, mem=mem)

That's all that's needed to start the I2C target.  From then on it will
respond to any I2C controller on the bus, allowing reads and writes to the
mem bytearray.

It's also possible to register to receive events.  For example to be
notified when the memory is read/written:

    from machine import I2CTarget

    def irq_handler(i2c_target):
        flags = i2c_target.irq().flags()
        if flags & I2CTarget.IRQ_END_READ:
            print("controller read target at addr", i2c_target.memaddr)
        if flags & I2CTarget.IRQ_END_WRITE:
            print("controller wrote target at addr", i2c_target.memaddr)

    mem = bytearray(8)
    i2c = I2CTarget(addr=67, mem=mem)
    i2c.irq(irq_handler)

Instead of a memory device, an arbitrary I2C device can be implemented
using all the events (see docs).

This is based on the discussion in #3935.

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

5 files changed, 435 insertions, 0 deletions

diff --git a/extmod/extmod.cmake b/extmod/extmod.cmake
index 7cacd0a43..9ca869582 100644
--- a/extmod/extmod.cmake
+++ b/extmod/extmod.cmake
@@ -11,6 +11,7 @@ set(MICROPY_SOURCE_EXTMOD
     ${MICROPY_EXTMOD_DIR}/machine_adc_block.c
     ${MICROPY_EXTMOD_DIR}/machine_bitstream.c
     ${MICROPY_EXTMOD_DIR}/machine_i2c.c
+    ${MICROPY_EXTMOD_DIR}/machine_i2c_target.c
     ${MICROPY_EXTMOD_DIR}/machine_i2s.c
     ${MICROPY_EXTMOD_DIR}/machine_mem.c
     ${MICROPY_EXTMOD_DIR}/machine_pulse.c
diff --git a/extmod/extmod.mk b/extmod/extmod.mk
index 997dd3ba9..37151ad12 100644
--- a/extmod/extmod.mk
+++ b/extmod/extmod.mk
@@ -6,6 +6,7 @@ SRC_EXTMOD_C += \
 	extmod/machine_adc_block.c \
 	extmod/machine_bitstream.c \
 	extmod/machine_i2c.c \
+	extmod/machine_i2c_target.c \
 	extmod/machine_i2s.c \
 	extmod/machine_mem.c \
 	extmod/machine_pinbase.c \
diff --git a/extmod/machine_i2c_target.c b/extmod/machine_i2c_target.c
new file mode 100644
index 000000000..f63be183c
--- /dev/null
+++ b/extmod/machine_i2c_target.c
@@ -0,0 +1,424 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2025 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_I2C_TARGET
+
+#include "extmod/modmachine.h"
+#include "shared/runtime/mpirq.h"
+
+enum {
+    // Events exposed to Python.
+    I2C_TARGET_IRQ_ADDR_MATCH_READ = 1 << 0,
+    I2C_TARGET_IRQ_ADDR_MATCH_WRITE = 1 << 1,
+    I2C_TARGET_IRQ_READ_REQ = 1 << 2,
+    I2C_TARGET_IRQ_WRITE_REQ = 1 << 3,
+    I2C_TARGET_IRQ_END_READ = 1 << 4,
+    I2C_TARGET_IRQ_END_WRITE = 1 << 5,
+
+    // Internal event, not exposed to Python.
+    I2C_TARGET_IRQ_MEM_ADDR_MATCH = 1 << 6,
+};
+
+// Define the IRQs that require a hard interrupt.
+#define I2C_TARGET_IRQ_ALL_HARD ( \
+    I2C_TARGET_IRQ_ADDR_MATCH_READ \
+    | I2C_TARGET_IRQ_ADDR_MATCH_WRITE \
+    | I2C_TARGET_IRQ_READ_REQ \
+    | I2C_TARGET_IRQ_WRITE_REQ \
+    )
+
+enum {
+    STATE_INACTIVE,
+    STATE_IDLE,
+    STATE_ADDR_MATCH_READ,
+    STATE_ADDR_MATCH_WRITE,
+    STATE_MEM_ADDR_SELECT,
+    STATE_READING,
+    STATE_WRITING,
+};
+
+typedef struct _machine_i2c_target_data_t {
+    uint8_t state;
+    uint8_t mem_addr_count;
+    uint8_t mem_addrsize;
+    uint32_t mem_addr_last;
+    uint32_t mem_addr;
+    uint32_t mem_len;
+    uint8_t *mem_buf;
+} machine_i2c_target_data_t;
+
+typedef struct _machine_i2c_target_irq_obj_t {
+    mp_irq_obj_t base;
+    uint32_t flags;
+    uint32_t trigger;
+} machine_i2c_target_irq_obj_t;
+
+// The port must provide implementations of these low-level I2C target functions.
+
+static void mp_machine_i2c_target_event_callback(machine_i2c_target_irq_obj_t *irq);
+
+// Read up to N bytes, and return the number of bytes read.
+static size_t mp_machine_i2c_target_read_bytes(machine_i2c_target_obj_t *self, size_t len, uint8_t *buf);
+
+// Write (or buffer) N bytes, and return the number of bytes written/buffered.
+static size_t mp_machine_i2c_target_write_bytes(machine_i2c_target_obj_t *self, size_t len, const uint8_t *buf);
+
+// Configure the given events to trigger an interrupt.
+static void mp_machine_i2c_target_irq_config(machine_i2c_target_obj_t *self, unsigned int trigger);
+
+static mp_obj_t mp_machine_i2c_target_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args);
+static void mp_machine_i2c_target_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind);
+static void mp_machine_i2c_target_deinit(machine_i2c_target_obj_t *self);
+
+static const mp_irq_methods_t machine_i2c_target_irq_methods;
+
+static machine_i2c_target_data_t machine_i2c_target_data[MICROPY_PY_MACHINE_I2C_TARGET_MAX];
+
+// Needed to retain a root pointer to the memory object.
+MP_REGISTER_ROOT_POINTER(mp_obj_t machine_i2c_target_mem_obj[MICROPY_PY_MACHINE_I2C_TARGET_MAX]);
+
+// Needed to retain a root pointer to the IRQ object.
+MP_REGISTER_ROOT_POINTER(void *machine_i2c_target_irq_obj[MICROPY_PY_MACHINE_I2C_TARGET_MAX]);
+
+static bool handle_event(machine_i2c_target_data_t *data, unsigned int trigger) {
+    unsigned int id = data - &machine_i2c_target_data[0];
+    if (trigger & I2C_TARGET_IRQ_MEM_ADDR_MATCH) {
+        data->mem_addr_last = data->mem_addr;
+    }
+    machine_i2c_target_irq_obj_t *irq = MP_STATE_PORT(machine_i2c_target_irq_obj[id]);
+    if (irq != NULL && (trigger & irq->trigger)) {
+        irq->flags = trigger & irq->trigger;
+        mp_machine_i2c_target_event_callback(irq);
+        return true; // irq handled
+    }
+    return false; // irq not handled
+}
+
+static void machine_i2c_target_data_init(machine_i2c_target_data_t *data, mp_obj_t mem_obj, mp_int_t mem_addrsize) {
+    data->state = STATE_IDLE;
+    data->mem_addr_count = 0;
+    data->mem_addrsize = 0;
+    data->mem_addr_last = 0;
+    data->mem_addr = 0;
+    data->mem_len = 0;
+    data->mem_buf = NULL;
+    if (mem_obj != mp_const_none) {
+        mp_buffer_info_t bufinfo;
+        mp_get_buffer_raise(mem_obj, &bufinfo, MP_BUFFER_RW);
+        if (mem_addrsize < 0 || mem_addrsize > 32 || mem_addrsize % 8 != 0) {
+            mp_raise_ValueError(MP_ERROR_TEXT("mem_addrsize must be 0, 8, 16, 24 or 32"));
+        }
+        data->mem_addrsize = mem_addrsize / 8;
+        data->mem_len = bufinfo.len;
+        data->mem_buf = bufinfo.buf;
+    }
+}
+
+static void machine_i2c_target_data_reset_helper(machine_i2c_target_data_t *data) {
+    if (data->state == STATE_READING) {
+        handle_event(data, I2C_TARGET_IRQ_END_READ);
+    } else if (data->state == STATE_ADDR_MATCH_WRITE || data->state == STATE_WRITING) {
+        handle_event(data, I2C_TARGET_IRQ_END_WRITE);
+    }
+    data->state = STATE_IDLE;
+}
+
+static void machine_i2c_target_data_addr_match(machine_i2c_target_data_t *data, bool read) {
+    machine_i2c_target_data_reset_helper(data);
+    if (read) {
+        handle_event(data, I2C_TARGET_IRQ_ADDR_MATCH_READ);
+        data->state = STATE_ADDR_MATCH_READ;
+    } else {
+        handle_event(data, I2C_TARGET_IRQ_ADDR_MATCH_WRITE);
+        data->state = STATE_ADDR_MATCH_WRITE;
+    }
+}
+
+static void machine_i2c_target_data_read_request(machine_i2c_target_obj_t *self, machine_i2c_target_data_t *data) {
+    // Let the user handle the read request.
+    bool event_handled = handle_event(data, I2C_TARGET_IRQ_READ_REQ);
+    if (data->mem_buf == NULL) {
+        data->state = STATE_READING;
+        if (!event_handled) {
+            // No data source, just write out a zero.
+            uint8_t val = 0;
+            mp_machine_i2c_target_write_bytes(self, 1, &val);
+        }
+    } else {
+        // Have a buffer.
+        if (data->state == STATE_MEM_ADDR_SELECT) {
+            // Got a short memory address.
+            data->mem_addr %= data->mem_len;
+            handle_event(data, I2C_TARGET_IRQ_MEM_ADDR_MATCH);
+        }
+        if (data->state != STATE_READING) {
+            data->state = STATE_READING;
+        }
+        uint8_t val = data->mem_buf[data->mem_addr++];
+        if (data->mem_addr >= data->mem_len) {
+            data->mem_addr = 0;
+        }
+        mp_machine_i2c_target_write_bytes(self, 1, &val);
+    }
+}
+
+static void machine_i2c_target_data_write_request(machine_i2c_target_obj_t *self, machine_i2c_target_data_t *data) {
+    // Let the user handle the write request.
+    bool event_handled = handle_event(data, I2C_TARGET_IRQ_WRITE_REQ);
+    if (data->mem_buf == NULL) {
+        data->state = STATE_WRITING;
+        if (!event_handled) {
+            // No data sink, just read and discard the incoming byte.
+            uint8_t buf = 0;
+            mp_machine_i2c_target_read_bytes(self, 1, &buf);
+        }
+    } else {
+        // Have a buffer.
+        uint8_t buf[4] = {0};
+        size_t n = mp_machine_i2c_target_read_bytes(self, sizeof(buf), &buf[0]);
+        for (size_t i = 0; i < n; ++i) {
+            uint8_t val = buf[i];
+            if (data->state == STATE_ADDR_MATCH_WRITE) {
+                data->state = STATE_MEM_ADDR_SELECT;
+                data->mem_addr = 0;
+                data->mem_addr_count = data->mem_addrsize;
+            }
+            if (data->state == STATE_MEM_ADDR_SELECT && data->mem_addr_count > 0) {
+                data->mem_addr = data->mem_addr << 8 | val;
+                --data->mem_addr_count;
+                if (data->mem_addr_count == 0) {
+                    data->mem_addr %= data->mem_len;
+                    handle_event(data, I2C_TARGET_IRQ_MEM_ADDR_MATCH);
+                }
+            } else {
+                if (data->state == STATE_MEM_ADDR_SELECT) {
+                    data->state = STATE_WRITING;
+                }
+                data->mem_buf[data->mem_addr++] = val;
+                if (data->mem_addr >= data->mem_len) {
+                    data->mem_addr = 0;
+                }
+            }
+        }
+    }
+}
+
+static inline void machine_i2c_target_data_restart_or_stop(machine_i2c_target_data_t *data) {
+    machine_i2c_target_data_reset_helper(data);
+}
+
+static inline void machine_i2c_target_data_stop(machine_i2c_target_data_t *data) {
+    machine_i2c_target_data_reset_helper(data);
+}
+
+// The port provides implementations of its bindings in this file.
+#include MICROPY_PY_MACHINE_I2C_TARGET_INCLUDEFILE
+
+static void machine_i2c_target_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
+    machine_i2c_target_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    size_t index = mp_machine_i2c_target_get_index(self);
+    machine_i2c_target_data_t *data = &machine_i2c_target_data[index];
+    if (dest[0] == MP_OBJ_NULL) {
+        // Load attribute.
+        if (attr == MP_QSTR_memaddr) {
+            dest[0] = mp_obj_new_int(data->mem_addr_last);
+        } else {
+            // Continue lookup in locals_dict.
+            dest[1] = MP_OBJ_SENTINEL;
+        }
+    }
+}
+
+// I2CTarget.deinit()
+static mp_obj_t machine_i2c_target_deinit(mp_obj_t self_in) {
+    machine_i2c_target_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    size_t index = mp_machine_i2c_target_get_index(self);
+    if (machine_i2c_target_data[index].state != STATE_INACTIVE) {
+        machine_i2c_target_data[index].state = STATE_INACTIVE;
+        mp_machine_i2c_target_deinit(self);
+        MP_STATE_PORT(machine_i2c_target_mem_obj[index]) = MP_OBJ_NULL;
+        MP_STATE_PORT(machine_i2c_target_irq_obj[index]) = NULL;
+    }
+    return mp_const_none;
+}
+static MP_DEFINE_CONST_FUN_OBJ_1(machine_i2c_target_deinit_obj, machine_i2c_target_deinit);
+
+// I2CTarget.readinto(buf)
+static mp_obj_t machine_i2c_target_readinto(mp_obj_t self_in, mp_obj_t buf_in) {
+    machine_i2c_target_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(buf_in, &bufinfo, MP_BUFFER_READ);
+    return MP_OBJ_NEW_SMALL_INT(mp_machine_i2c_target_read_bytes(self, bufinfo.len, bufinfo.buf));
+}
+static MP_DEFINE_CONST_FUN_OBJ_2(machine_i2c_target_readinto_obj, machine_i2c_target_readinto);
+
+// I2CTarget.write(data)
+static mp_obj_t machine_i2c_target_write(mp_obj_t self_in, mp_obj_t data_in) {
+    machine_i2c_target_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(data_in, &bufinfo, MP_BUFFER_READ);
+    return MP_OBJ_NEW_SMALL_INT(mp_machine_i2c_target_write_bytes(self, bufinfo.len, bufinfo.buf));
+}
+static MP_DEFINE_CONST_FUN_OBJ_2(machine_i2c_target_write_obj, machine_i2c_target_write);
+
+static machine_i2c_target_irq_obj_t *machine_i2c_target_get_irq(machine_i2c_target_obj_t *self) {
+    // Get the IRQ object.
+    size_t index = mp_machine_i2c_target_get_index(self);
+    machine_i2c_target_irq_obj_t *irq = MP_STATE_PORT(machine_i2c_target_irq_obj[index]);
+
+    // Allocate the IRQ object if it doesn't already exist.
+    if (irq == NULL) {
+        irq = m_new_obj(machine_i2c_target_irq_obj_t);
+        irq->base.base.type = &mp_irq_type;
+        irq->base.methods = (mp_irq_methods_t *)&machine_i2c_target_irq_methods;
+        irq->base.parent = MP_OBJ_FROM_PTR(self);
+        irq->base.handler = mp_const_none;
+        irq->base.ishard = false;
+        MP_STATE_PORT(machine_i2c_target_irq_obj[index]) = irq;
+    }
+    return irq;
+}
+
+// I2CTarget.irq(handler=None, trigger=IRQ_END_READ|IRQ_END_WRITE, hard=False)
+static mp_obj_t machine_i2c_target_irq(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum { ARG_handler, ARG_trigger, ARG_hard };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_handler, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_trigger, MP_ARG_INT, {.u_int = I2C_TARGET_IRQ_END_READ | I2C_TARGET_IRQ_END_WRITE} },
+        { MP_QSTR_hard, MP_ARG_BOOL, {.u_bool = false} },
+    };
+    machine_i2c_target_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
+
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    machine_i2c_target_irq_obj_t *irq = machine_i2c_target_get_irq(self);
+
+    if (n_args > 1 || kw_args->used != 0) {
+        // Update IRQ data.
+        mp_obj_t handler = args[ARG_handler].u_obj;
+        mp_uint_t trigger = args[ARG_trigger].u_int;
+        bool hard = args[ARG_hard].u_bool;
+
+        #if MICROPY_PY_MACHINE_I2C_TARGET_HARD_IRQ
+        if ((trigger & I2C_TARGET_IRQ_ALL_HARD) && !hard) {
+            mp_raise_ValueError(MP_ERROR_TEXT("hard IRQ required"));
+        }
+        #else
+        if (hard) {
+            mp_raise_ValueError(MP_ERROR_TEXT("hard IRQ unsupported"));
+        }
+        #endif
+
+        // Disable all IRQs while data is updated.
+        mp_machine_i2c_target_irq_config(self, 0);
+
+        // Update IRQ data.
+        irq->base.handler = handler;
+        irq->base.ishard = hard;
+        irq->flags = 0;
+        irq->trigger = trigger;
+
+        // Enable IRQ if a handler is given.
+        if (handler != mp_const_none && trigger != 0) {
+            mp_machine_i2c_target_irq_config(self, trigger);
+        }
+    }
+    return MP_OBJ_FROM_PTR(irq);
+}
+static MP_DEFINE_CONST_FUN_OBJ_KW(machine_i2c_target_irq_obj, 1, machine_i2c_target_irq);
+
+static const mp_rom_map_elem_t machine_i2c_target_locals_dict_table[] = {
+    #if MICROPY_PY_MACHINE_I2C_TARGET_FINALISER
+    { MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&machine_i2c_target_deinit_obj) },
+    #endif
+    { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&machine_i2c_target_deinit_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&machine_i2c_target_readinto_obj) },
+    { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&machine_i2c_target_write_obj) },
+    { MP_ROM_QSTR(MP_QSTR_irq), MP_ROM_PTR(&machine_i2c_target_irq_obj) },
+
+    #if MICROPY_PY_MACHINE_I2C_TARGET_HARD_IRQ
+    { MP_ROM_QSTR(MP_QSTR_IRQ_ADDR_MATCH_READ), MP_ROM_INT(I2C_TARGET_IRQ_ADDR_MATCH_READ) },
+    { MP_ROM_QSTR(MP_QSTR_IRQ_ADDR_MATCH_WRITE), MP_ROM_INT(I2C_TARGET_IRQ_ADDR_MATCH_WRITE) },
+    { MP_ROM_QSTR(MP_QSTR_IRQ_READ_REQ), MP_ROM_INT(I2C_TARGET_IRQ_READ_REQ) },
+    { MP_ROM_QSTR(MP_QSTR_IRQ_WRITE_REQ), MP_ROM_INT(I2C_TARGET_IRQ_WRITE_REQ) },
+    #endif
+    { MP_ROM_QSTR(MP_QSTR_IRQ_END_READ), MP_ROM_INT(I2C_TARGET_IRQ_END_READ) },
+    { MP_ROM_QSTR(MP_QSTR_IRQ_END_WRITE), MP_ROM_INT(I2C_TARGET_IRQ_END_WRITE) },
+};
+static MP_DEFINE_CONST_DICT(machine_i2c_target_locals_dict, machine_i2c_target_locals_dict_table);
+
+MP_DEFINE_CONST_OBJ_TYPE(
+    machine_i2c_target_type,
+    MP_QSTR_I2CTarget,
+    MP_TYPE_FLAG_NONE,
+    make_new, mp_machine_i2c_target_make_new,
+    print, mp_machine_i2c_target_print,
+    attr, &machine_i2c_target_attr,
+    locals_dict, &machine_i2c_target_locals_dict
+    );
+
+static mp_uint_t machine_i2c_target_irq_trigger(mp_obj_t self_in, mp_uint_t new_trigger) {
+    machine_i2c_target_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    size_t index = mp_machine_i2c_target_get_index(self);
+    machine_i2c_target_irq_obj_t *irq = MP_STATE_PORT(machine_i2c_target_irq_obj[index]);
+    mp_machine_i2c_target_irq_config(self, 0);
+    irq->flags = 0;
+    irq->trigger = new_trigger;
+    mp_machine_i2c_target_irq_config(self, new_trigger);
+    return 0;
+}
+
+static mp_uint_t machine_i2c_target_irq_info(mp_obj_t self_in, mp_uint_t info_type) {
+    machine_i2c_target_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    size_t index = mp_machine_i2c_target_get_index(self);
+    machine_i2c_target_irq_obj_t *irq = MP_STATE_PORT(machine_i2c_target_irq_obj[index]);
+    if (info_type == MP_IRQ_INFO_FLAGS) {
+        return irq->flags;
+    } else if (info_type == MP_IRQ_INFO_TRIGGERS) {
+        return irq->trigger;
+    }
+    return 0;
+}
+
+static const mp_irq_methods_t machine_i2c_target_irq_methods = {
+    .trigger = machine_i2c_target_irq_trigger,
+    .info = machine_i2c_target_irq_info,
+};
+
+#if !MICROPY_PY_MACHINE_I2C_TARGET_FINALISER
+void mp_machine_i2c_target_deinit_all(void) {
+    for (size_t i = 0; i < MICROPY_PY_MACHINE_I2C_TARGET_MAX; ++i) {
+        if (machine_i2c_target_data[i].state != STATE_INACTIVE) {
+            machine_i2c_target_deinit(MP_OBJ_FROM_PTR(&machine_i2c_target_obj[i]));
+        }
+    }
+}
+#endif
+
+#endif // MICROPY_PY_MACHINE_I2C_TARGET
diff --git a/extmod/modmachine.c b/extmod/modmachine.c
index f2570123e..28b60683b 100644
--- a/extmod/modmachine.c
+++ b/extmod/modmachine.c
@@ -219,6 +219,9 @@ static const mp_rom_map_elem_t machine_module_globals_table[] = {
     #if MICROPY_PY_MACHINE_I2C
     { MP_ROM_QSTR(MP_QSTR_I2C), MP_ROM_PTR(&machine_i2c_type) },
     #endif
+    #if MICROPY_PY_MACHINE_I2C_TARGET
+    { MP_ROM_QSTR(MP_QSTR_I2CTarget), MP_ROM_PTR(&machine_i2c_target_type) },
+    #endif
     #if MICROPY_PY_MACHINE_I2S
     { MP_ROM_QSTR(MP_QSTR_I2S), MP_ROM_PTR(&machine_i2s_type) },
     #endif
diff --git a/extmod/modmachine.h b/extmod/modmachine.h
index 26010be8e..ef507aca7 100644
--- a/extmod/modmachine.h
+++ b/extmod/modmachine.h
@@ -129,6 +129,7 @@
 // A port must provide these types, but they are otherwise opaque.
 typedef struct _machine_adc_obj_t machine_adc_obj_t;
 typedef struct _machine_adc_block_obj_t machine_adc_block_obj_t;
+typedef struct _machine_i2c_target_obj_t machine_i2c_target_obj_t;
 typedef struct _machine_i2s_obj_t machine_i2s_obj_t;
 typedef struct _machine_pwm_obj_t machine_pwm_obj_t;
 typedef struct _machine_uart_obj_t machine_uart_obj_t;
@@ -203,6 +204,7 @@ extern const machine_mem_obj_t machine_mem32_obj;
 extern const mp_obj_type_t machine_adc_type;
 extern const mp_obj_type_t machine_adc_block_type;
 extern const mp_obj_type_t machine_i2c_type;
+extern const mp_obj_type_t machine_i2c_target_type;
 extern const mp_obj_type_t machine_i2s_type;
 extern const mp_obj_type_t machine_mem_type;
 extern const mp_obj_type_t machine_pin_type;
@@ -261,6 +263,10 @@ int mp_machine_i2c_transfer_adaptor(mp_obj_base_t *self, uint16_t addr, size_t n
 int mp_machine_soft_i2c_transfer(mp_obj_base_t *self, uint16_t addr, size_t n, mp_machine_i2c_buf_t *bufs, unsigned int flags);
 #endif
 
+#if MICROPY_PY_MACHINE_I2C_TARGET
+void mp_machine_i2c_target_deinit_all(void);
+#endif
+
 #if MICROPY_PY_MACHINE_SPI
 mp_obj_t mp_machine_spi_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args);
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_machine_spi_read_obj);