samples: pmci: mctp: Add i2c+gpio endpoint sample

cmake_minimum_required(VERSION 3.20.0)

find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})

project(mctp_i2c_gpio_bus_endpoint)

target_sources(app PRIVATE src/main.c)

.. zephyr:code-sample:: mctp_i2c_bus_endpoint

   :name: MCTP I2C GPIO Endpoint Node Sample

   Create an MCTP endpoint node controlling I2C with GPIO signaling.

Overview

********

Sets up an MCTP endpoint node that may talk to a top node and peer to other MCTP endpoints.

Requirements

************

Board with an I2C and a GPIO used for signaling the top node to read the target device.

Wiring

******

A common I2C bus SDA/SCL pair connected to any number of boards (setup in devicetree)

along with a GPIO for signaling endpoint write requests.

Building and Running

********************

.. zephyr-app-commands::

   :zephyr-app: samples/modules/pmci/mctp/i2c_gpio_bus_endpoint

   :host-os: unix

   :board: frdm_mcxn947_mcxn947_cpu0

   :goals: run

   :compact:

References

**********

`MCTP Base Specification 2019 <https://www.dmtf.org/sites/default/files/standards/documents/DSP0236_1.3.1.pdf>`_

#include <zephyr/dt-bindings/gpio/gpio.h>

/* Sets up I2C and a GPIO on JP8 to use as our i2c bus for MCTP */

&nxp_lcd_8080_connector {

	status = "disabled";

};

&flexio0 {

	status = "disabled";

};

&gpio0 {

	status = "okay";

};

&flexcomm2 {

	status = "okay";

};

&flexcomm2_lpi2c2 {

	status = "okay";

	clock-frequency = <I2C_BITRATE_STANDARD>;

};

/ {

	mctp_i2c: mctp_i2c {

		compatible = "zephyr,mctp-i2c-gpio-target";

		i2c = <&flexcomm2_lpi2c2>;

		i2c-addr = <70>;

		endpoint-id = <11>;

		endpoint-gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>;

	};

};

CONFIG_I2C=y

CONFIG_I2C_TARGET=y

CONFIG_MCTP=y

CONFIG_MCTP_I2C_GPIO_TARGET=y

CONFIG_MCTP_LOG_LEVEL_DBG=y

CONFIG_LOG=y

#CONFIG_LOG_MODE_IMMEDIATE=y

CONFIG_LOG_BUFFER_SIZE=4096

/*

 * Copyright (c) 2025 Intel Corporation

 *

 * SPDX-License-Identifier: Apache-2.0

 */

#include <stdlib.h>

#include <stdio.h>

#include <assert.h>

#include <unistd.h>

#include <zephyr/types.h>

#include <zephyr/kernel.h>

#include <libmctp.h>

#include <zephyr/pmci/mctp/mctp_i2c_gpio_target.h>

#include <zephyr/logging/log.h>

LOG_MODULE_REGISTER(mctp_i2c_gpio_bus_endpoint);

MCTP_I2C_GPIO_TARGET_DT_DEFINE(mctp_i2c_ctrl, DT_NODELABEL(mctp_i2c));

static void rx_message(uint8_t eid, bool tag_owner, uint8_t msg_tag, void *data, void *msg,

		       size_t len)

{

	LOG_INF("received message \"%s\" from endpoint %d, msg_tag %d, len %zu", (char *)msg, eid,

		msg_tag, len);

}

#define BUS_OWNER_ID 20

int main(void)

{

	int rc;

	struct mctp *mctp_ctx;

	LOG_INF("MCTP Host EID:%d on %s\n", mctp_i2c_ctrl.endpoint_id, CONFIG_BOARD_TARGET);

	mctp_ctx = mctp_init();

	__ASSERT_NO_MSG(mctp_ctx != NULL);

	mctp_register_bus(mctp_ctx, &mctp_i2c_ctrl.binding, mctp_i2c_ctrl.endpoint_id);

	mctp_set_rx_all(mctp_ctx, rx_message, NULL);

	/*

	 * 1. MCTP poll loop, send "ping" to each endpoint and get "pong" back

	 * 2. Then send a broadcast "hello" to each endpoint and get a "from endoint %d" back

	 */

	while (true) {

		rc = mctp_message_tx(mctp_ctx, BUS_OWNER_ID, false,

				0, "ping", sizeof("ping"));

		if (rc != 0) {

			LOG_WRN("Failed to send message \"ping\", errno %d\n", rc);

		}

		k_msleep(500);

	}

	return 0;

}