rp2/machine_i2c_target: Implement I2CTarget class.

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

3 files changed, 312 insertions, 0 deletions

diff --git a/ports/rp2/machine_i2c_target.c b/ports/rp2/machine_i2c_target.c
new file mode 100644
index 000000000..dc3010727
--- /dev/null
+++ b/ports/rp2/machine_i2c_target.c
@@ -0,0 +1,304 @@
+/*
+ * 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.
+ */
+
+// This file is never compiled standalone, it's included directly from
+// extmod/machine_i2c_target.c via MICROPY_PY_MACHINE_I2C_TARGET_INCLUDEFILE.
+
+#include "machine_i2c.h"
+#include "hardware/i2c.h"
+
+typedef struct _machine_i2c_target_obj_t {
+    mp_obj_base_t base;
+    i2c_inst_t *const i2c_inst;
+    mp_hal_pin_obj_t scl;
+    mp_hal_pin_obj_t sda;
+    uint8_t state;
+    bool stop_pending;
+    bool irq_active;
+} machine_i2c_target_obj_t;
+
+static machine_i2c_target_obj_t machine_i2c_target_obj[] = {
+    {{&machine_i2c_target_type}, i2c0, MICROPY_HW_I2C0_SCL, MICROPY_HW_I2C0_SDA},
+    {{&machine_i2c_target_type}, i2c1, MICROPY_HW_I2C1_SCL, MICROPY_HW_I2C1_SDA},
+};
+
+/******************************************************************************/
+// RP2xxx hardware bindings
+
+static void check_stop_pending(machine_i2c_target_obj_t *self) {
+    if (self->irq_active) {
+        return;
+    }
+    if (self->stop_pending && !(self->i2c_inst->hw->status & I2C_IC_STATUS_RFNE_BITS)) {
+        unsigned int i2c_id = self - &machine_i2c_target_obj[0];
+        machine_i2c_target_data_t *data = &machine_i2c_target_data[i2c_id];
+        self->stop_pending = false;
+        self->state = STATE_IDLE;
+        machine_i2c_target_data_restart_or_stop(data);
+    }
+}
+
+static void i2c_target_handler(i2c_inst_t *i2c) {
+    unsigned int i2c_id = i2c == i2c0 ? 0 : 1;
+    machine_i2c_target_obj_t *self = &machine_i2c_target_obj[i2c_id];
+    machine_i2c_target_data_t *data = &machine_i2c_target_data[i2c_id];
+
+    self->irq_active = true;
+
+    // Get the interrupt status.
+    uint32_t intr_stat = i2c->hw->intr_stat;
+
+    if (intr_stat & I2C_IC_INTR_STAT_R_TX_ABRT_BITS) {
+        // Clear the TX_ABRT condition.
+        (void)i2c->hw->clr_tx_abrt;
+    }
+
+    if (intr_stat & I2C_IC_INTR_STAT_R_START_DET_BITS) {
+        // Controller sent a start condition.
+        // Reset all state machines in case something went wrong.
+        (void)i2c->hw->clr_start_det;
+        if (self->state != STATE_IDLE) {
+            machine_i2c_target_data_reset_helper(data);
+            self->state = STATE_IDLE;
+        }
+    }
+
+    if (intr_stat & I2C_IC_INTR_STAT_R_RX_FULL_BITS) {
+        // Data from controller is available for reading.
+        // Mask interrupt until I2C_DATA_CMD is read from.
+        i2c->hw->intr_mask &= ~I2C_IC_INTR_MASK_M_RX_FULL_BITS;
+        if (self->state != STATE_WRITING) {
+            machine_i2c_target_data_addr_match(data, false);
+        }
+        machine_i2c_target_data_write_request(self, data);
+        self->state = STATE_WRITING;
+    }
+
+    if (intr_stat & (I2C_IC_INTR_STAT_R_RD_REQ_BITS | I2C_IC_INTR_STAT_R_RX_DONE_BITS)) {
+        // Controller is requesting data.
+        (void)i2c->hw->clr_rx_done;
+        (void)i2c->hw->clr_rd_req;
+        i2c->hw->intr_mask &= ~I2C_IC_INTR_MASK_M_RD_REQ_BITS;
+        if (self->state != STATE_READING) {
+            machine_i2c_target_data_addr_match(data, true);
+        }
+        machine_i2c_target_data_read_request(self, data);
+        self->state = STATE_READING;
+    }
+
+    if (intr_stat & I2C_IC_INTR_STAT_R_STOP_DET_BITS) {
+        // Controller has generated a stop condition.
+        (void)i2c->hw->clr_stop_det;
+        if (self->state == STATE_IDLE) {
+            machine_i2c_target_data_addr_match(data, false);
+        }
+        if (i2c->hw->status & I2C_IC_STATUS_RFNE_BITS) {
+            self->stop_pending = true;
+        } else {
+            machine_i2c_target_data_restart_or_stop(data);
+            self->state = STATE_IDLE;
+        }
+    }
+
+    self->irq_active = false;
+    check_stop_pending(self);
+}
+
+static void i2c_target_irq_handler(void) {
+    uint i2c_index = __get_current_exception() - VTABLE_FIRST_IRQ - I2C0_IRQ;
+    i2c_inst_t *i2c = i2c_get_instance(i2c_index);
+    i2c_target_handler(i2c);
+}
+
+static void i2c_target_init(i2c_inst_t *i2c, uint16_t addr, bool addr_10bit) {
+    i2c->hw->enable = 0;
+
+    // Configure general settings, target address and FIFO levels.
+    i2c->hw->con =
+        I2C_IC_CON_RX_FIFO_FULL_HLD_CTRL_BITS
+        | I2C_IC_CON_STOP_DET_IFADDRESSED_BITS;
+    if (addr_10bit) {
+        i2c->hw->con |= I2C_IC_CON_IC_10BITADDR_SLAVE_BITS;
+    }
+    i2c->hw->sar = addr;
+    i2c->hw->tx_tl = 1;
+    i2c->hw->rx_tl = 0; // interrupt when at least 1 byte is available
+    (void)i2c->hw->clr_intr;
+
+    // Enable interrupts.
+    i2c->hw->intr_mask =
+        I2C_IC_INTR_MASK_M_START_DET_BITS
+        | I2C_IC_INTR_MASK_M_STOP_DET_BITS
+        | I2C_IC_INTR_MASK_M_RX_DONE_BITS
+        | I2C_IC_INTR_MASK_M_TX_ABRT_BITS
+        | I2C_IC_INTR_MASK_M_RD_REQ_BITS
+        | I2C_IC_INTR_MASK_M_RX_FULL_BITS
+    ;
+
+    i2c->hw->enable = 1;
+
+    // Enable interrupt for current core.
+    uint i2c_index = i2c_hw_index(i2c);
+    uint num = I2C0_IRQ + i2c_index;
+    irq_set_exclusive_handler(num, i2c_target_irq_handler);
+    irq_set_enabled(num, true);
+}
+
+static void i2c_target_deinit(i2c_inst_t *i2c) {
+    uint i2c_index = i2c_hw_index(i2c);
+    uint num = I2C0_IRQ + i2c_index;
+    irq_set_enabled(num, false);
+    irq_remove_handler(num, i2c_target_irq_handler);
+
+    i2c->hw->intr_mask = 0;
+    i2c->hw->enable = 0;
+    i2c->hw->con = I2C_IC_CON_IC_SLAVE_DISABLE_BITS;
+}
+
+/******************************************************************************/
+// I2CTarget port implementation
+
+static inline size_t mp_machine_i2c_target_get_index(machine_i2c_target_obj_t *self) {
+    return self - &machine_i2c_target_obj[0];
+}
+
+static inline void mp_machine_i2c_target_event_callback(machine_i2c_target_irq_obj_t *irq) {
+    mp_irq_handler(&irq->base);
+}
+
+static size_t mp_machine_i2c_target_read_bytes(machine_i2c_target_obj_t *self, size_t len, uint8_t *buf) {
+    i2c_hw_t *i2c_hw = self->i2c_inst->hw;
+
+    // Read from the RX FIFO.
+    size_t i = 0;
+    while (i < len && (i2c_hw->status & I2C_IC_STATUS_RFNE_BITS)) {
+        buf[i++] = i2c_hw->data_cmd;
+    }
+
+    // Re-enable RX_FULL interrupt.
+    i2c_hw->intr_mask |= I2C_IC_INTR_MASK_M_RX_FULL_BITS;
+
+    check_stop_pending(self);
+
+    return i;
+}
+
+static size_t mp_machine_i2c_target_write_bytes(machine_i2c_target_obj_t *self, size_t len, const uint8_t *buf) {
+    i2c_hw_t *i2c_hw = self->i2c_inst->hw;
+
+    // Write to the TX FIFO.
+    size_t i = 0;
+    while (i < len && (i2c_hw->status & I2C_IC_STATUS_TFNF_BITS)) {
+        i2c_hw->data_cmd = buf[i++];
+    }
+
+    // Re-enable RD_REQ interrupt.
+    i2c_hw->intr_mask |= I2C_IC_INTR_MASK_M_RD_REQ_BITS;
+
+    return i;
+}
+
+static inline void mp_machine_i2c_target_irq_config(machine_i2c_target_obj_t *self, unsigned int trigger) {
+    (void)self;
+    (void)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 *all_args) {
+    enum { ARG_id, ARG_addr, ARG_addrsize, ARG_mem, ARG_mem_addrsize, ARG_scl, ARG_sda };
+    static const mp_arg_t allowed_args[] = {
+        #ifdef PICO_DEFAULT_I2C
+        { MP_QSTR_id, MP_ARG_INT, {.u_int = PICO_DEFAULT_I2C} },
+        #else
+        { MP_QSTR_id, MP_ARG_INT | MP_ARG_REQUIRED },
+        #endif
+        { MP_QSTR_addr, MP_ARG_REQUIRED | MP_ARG_INT },
+        { MP_QSTR_addrsize, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 7} },
+        { MP_QSTR_mem, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_mem_addrsize, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 8} },
+        { MP_QSTR_scl, MICROPY_I2C_PINS_ARG_OPTS | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_sda, MICROPY_I2C_PINS_ARG_OPTS | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+    };
+
+    // Parse args.
+    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);
+
+    int i2c_id = args[ARG_id].u_int;
+
+    // Check if the I2C bus is valid
+    if (i2c_id < 0 || i2c_id >= MP_ARRAY_SIZE(machine_i2c_target_obj)) {
+        mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("I2CTarget(%d) doesn't exist"), i2c_id);
+    }
+
+    // Get static peripheral object.
+    machine_i2c_target_obj_t *self = &machine_i2c_target_obj[i2c_id];
+
+    // Set SCL/SDA pins if configured.
+    if (args[ARG_scl].u_obj != mp_const_none) {
+        int scl = mp_hal_get_pin_obj(args[ARG_scl].u_obj);
+        if (!IS_VALID_SCL(i2c_id, scl)) {
+            mp_raise_ValueError(MP_ERROR_TEXT("bad SCL pin"));
+        }
+        self->scl = scl;
+    }
+    if (args[ARG_sda].u_obj != mp_const_none) {
+        int sda = mp_hal_get_pin_obj(args[ARG_sda].u_obj);
+        if (!IS_VALID_SDA(i2c_id, sda)) {
+            mp_raise_ValueError(MP_ERROR_TEXT("bad SDA pin"));
+        }
+        self->sda = sda;
+    }
+
+    // Initialise I2C target state and data.
+    self->state = STATE_IDLE;
+    self->stop_pending = false;
+    self->irq_active = false;
+    MP_STATE_PORT(machine_i2c_target_mem_obj)[i2c_id] = args[ARG_mem].u_obj;
+    machine_i2c_target_data_t *data = &machine_i2c_target_data[i2c_id];
+    machine_i2c_target_data_init(data, args[ARG_mem].u_obj, args[ARG_mem_addrsize].u_int);
+
+    // Initialise I2C target hardware.
+    i2c_target_init(self->i2c_inst, args[ARG_addr].u_int, args[ARG_addrsize].u_int == 10);
+    gpio_set_function(self->scl, GPIO_FUNC_I2C);
+    gpio_set_function(self->sda, GPIO_FUNC_I2C);
+    gpio_set_pulls(self->scl, true, 0);
+    gpio_set_pulls(self->sda, true, 0);
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+static void mp_machine_i2c_target_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_i2c_target_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    i2c_hw_t *i2c_hw = i2c_get_hw(self->i2c_inst);
+    mp_printf(print, "I2CTarget(%u, addr=%u, scl=%u, sda=%u)",
+        self - &machine_i2c_target_obj[0], i2c_hw->sar, self->scl, self->sda);
+}
+
+static void mp_machine_i2c_target_deinit(machine_i2c_target_obj_t *self) {
+    gpio_set_function(self->scl, GPIO_FUNC_SIO);
+    gpio_set_function(self->sda, GPIO_FUNC_SIO);
+    i2c_target_deinit(self->i2c_inst);
+}
diff --git a/ports/rp2/main.c b/ports/rp2/main.c
index 0f10f63c6..1ffcabdfa 100644
--- a/ports/rp2/main.c
+++ b/ports/rp2/main.c
@@ -34,6 +34,7 @@
 #include "py/mperrno.h"
 #include "py/mphal.h"
 #include "extmod/modbluetooth.h"
+#include "extmod/modmachine.h"
 #include "extmod/modnetwork.h"
 #include "shared/readline/readline.h"
 #include "shared/runtime/gchelper.h"
@@ -257,6 +258,9 @@ int main(int argc, char **argv) {
         machine_pwm_deinit_all();
         machine_pin_deinit();
         machine_uart_deinit_all();
+        #if MICROPY_PY_MACHINE_I2C_TARGET
+        mp_machine_i2c_target_deinit_all();
+        #endif
         #if MICROPY_PY_THREAD
         mp_thread_deinit();
         #endif
diff --git a/ports/rp2/mpconfigport.h b/ports/rp2/mpconfigport.h
index 35afea4fa..d35563bd0 100644
--- a/ports/rp2/mpconfigport.h
+++ b/ports/rp2/mpconfigport.h
@@ -171,6 +171,10 @@
 #define MICROPY_PY_MACHINE_PWM                  (1)
 #define MICROPY_PY_MACHINE_PWM_INCLUDEFILE      "ports/rp2/machine_pwm.c"
 #define MICROPY_PY_MACHINE_I2C                  (1)
+#define MICROPY_PY_MACHINE_I2C_TARGET           (1)
+#define MICROPY_PY_MACHINE_I2C_TARGET_INCLUDEFILE "ports/rp2/machine_i2c_target.c"
+#define MICROPY_PY_MACHINE_I2C_TARGET_MAX       (2)
+#define MICROPY_PY_MACHINE_I2C_TARGET_HARD_IRQ  (1)
 #define MICROPY_PY_MACHINE_SOFTI2C              (1)
 #define MICROPY_PY_MACHINE_I2S                  (1)
 #define MICROPY_PY_MACHINE_I2S_INCLUDEFILE      "ports/rp2/machine_i2s.c"