samples: drivers: ipm: added esp32 sample

code to demonstrate the utilization of assymetric
dual core infrastructure based on soft-IPM implementation.

Signed-off-by: Felipe Neves <felipe.neves@linaro.org>

samples/drivers/ipm/ipm_esp32/CMakeLists.txt

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+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(ipm_esp32)
+
+target_sources(app PRIVATE src/main.c src/esp32_net_firmware.c)

samples/drivers/ipm/ipm_esp32/README.rst

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+.. _ipm_esp32:
+
+ESP32 Soft-IPM example
+######################
+
+Overview
+********
+This simple example can be used with multicore ESP32 Soc, and demonstrates
+the software intercore messaging mechanism to be used in AMP applications.
+
+ESP32 has two CPU named APP and PRO, in this simple example PRO send a
+message to the APP using the IPM driver, and waits for the APP response
+message and prints its contents on console.
+
+ESP32 intercore messaging has up two four channels, the 0 and 1 are
+reserved for BT and WIFI messages, and channels 2 and 3 is free to
+any application, each channel supports up to 64 bytes of data per
+message, so high level protocol is responsible to fragment larger
+messages in chunks of 64bytes.
+
+Building and Running the Zephyr Code
+************************************
+
+The sample requires two build commands to run, for that reason a pre built
+version of esp32_net, the APP cpu side firmware is already provided for quick
+tests just type on the console:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/drivers/ipm/ipm_esp32
+   :board: esp32
+   :goals: build flash
+   :compact:
+
+The other option is building from scratch just involve a single extra build command
+and file moving, first of all you need to build the esp32_net firmware as follows:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/drivers/ipm/ipm_esp32/ipm_esp32_net
+   :board: esp32_net
+   :goals: build
+   :compact:
+
+Copy output file build/zephyr/esp32_net_firmware.c to samples/drivers/ipm/ipm_esp32/src,
+then build the main project and flash as stated earlier, and you would see the following output:
+
+.. code-block:: console
+
+   *** Booting Zephyr OS build zephyr-v3.0.0-1911-g610f489c861e  ***
+   PRO_CPU is sending a fake request, waiting remote response...
+   PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
+   PRO_CPU is sending a fake request, waiting remote response...
+   PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
+   PRO_CPU is sending a fake request, waiting remote response...
+   PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
+   PRO_CPU is sending a fake request, waiting remote response...
+   PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
+   PRO_CPU is sending a fake request, waiting remote response...
+   PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
+   PRO_CPU is sending a fake request, waiting remote response...
+   PRO_CPU received a message from APP_CPU : APP_CPU: This is a response
+   PRO_CPU is sending a fake request, waiting remote response...
+   PRO_CPU received a message from APP_CPU : APP_CPU: This is a response

samples/drivers/ipm/ipm_esp32/ipm_esp32_net/CMakeLists.txt

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+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(ipm_esp32_net)
+
+target_sources(app PRIVATE src/main.c)

samples/drivers/ipm/ipm_esp32/ipm_esp32_net/prj.conf

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+CONFIG_HEAP_MEM_POOL_SIZE=256
+CONFIG_IPM=y
+CONFIG_ESP32_SOFT_IPM=y
+CONFIG_KERNEL_BIN_NAME="esp32_net_firmware"

samples/drivers/ipm/ipm_esp32/ipm_esp32_net/src/main.c

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+/*
+ * Copyright (c) 2022 Espressif Systems (Shanghai) Co., Ltd.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr.h>
+#include <sys/printk.h>
+#include <drivers/ipm.h>
+#include <device.h>
+
+static const struct device *ipm_dev;
+static const char fake_resp[] = {"APP_CPU: This is a response"};
+struct k_sem sync;
+
+static void ipm_receive_callback(const struct device *ipmdev, void *user_data,
+			       uint32_t id, volatile void *data)
+{
+	k_sem_give(&sync);
+}
+
+void main(void)
+{
+	k_sem_init(&sync, 0, 1);
+
+	ipm_dev = DEVICE_DT_GET(DT_NODELABEL(ipm0));
+	if (!ipm_dev) {
+		printk("Failed to get IPM device.\n\r");
+	}
+
+	ipm_register_callback(ipm_dev, ipm_receive_callback, NULL);
+
+	while (1) {
+		k_sem_take(&sync, K_FOREVER);
+		ipm_send(ipm_dev, -1, sizeof(fake_resp), &fake_resp, sizeof(fake_resp));
+	}
+}

samples/drivers/ipm/ipm_esp32/prj.conf

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+CONFIG_ESP32_NETWORK_CORE=y
+CONFIG_IPM=y
+CONFIG_ESP32_SOFT_IPM=y
+CONFIG_LOG=y

samples/drivers/ipm/ipm_esp32/sample.yaml

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+sample:
+  name: ESP32 IPM Sample
+tests:
+  sample.ipm.ipm_esp32:
+    platform_allow: esp32
+    tags: samples ipm

samples/drivers/ipm/ipm_esp32/src/main.c

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+/*
+ * Copyright (c) 2022 Espressif Systems (Shanghai) Co., Ltd.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr.h>
+#include <sys/printk.h>
+#include <drivers/ipm.h>
+#include <device.h>
+#include <string.h>
+
+static const char fake_request[] = {"PRO_CPU: Fake request to APP_CPU"};
+
+static const struct device *ipm_dev;
+static char received_string[64];
+static struct k_sem sync;
+
+static void ipm_receive_callback(const struct device *ipmdev, void *user_data,
+			       uint32_t id, volatile void *data)
+{
+	ARG_UNUSED(ipmdev);
+	ARG_UNUSED(user_data);
+
+	strcpy(received_string, (const char *)data);
+	k_sem_give(&sync);
+}
+
+void main(void)
+{
+	k_sem_init(&sync, 0, 1);
+
+	ipm_dev = DEVICE_DT_GET(DT_NODELABEL(ipm0));
+	if (!ipm_dev) {
+		printk("Failed to get IPM device.\n\r");
+	}
+
+	ipm_register_callback(ipm_dev, ipm_receive_callback, NULL);
+
+	while (1) {
+		printk("PRO_CPU is sending a fake request, waiting remote response...\n\r");
+
+		ipm_send(ipm_dev, -1, sizeof(fake_request), &fake_request, sizeof(fake_request));
+		k_sem_take(&sync, K_FOREVER);
+
+		printk("PRO_CPU received a message from APP_CPU : %s\n\r", received_string);
+
+		k_sleep(K_MSEC(200));
+	}
+}