drivers: mbox: add IVSHMEM based mbox driver

Add initial support of the mailbox driver based
on the inter VM shared memory mechanism similar
as the existing IPM driver.

Signed-off-by: Felipe Neves <ryukokki.felipe@gmail.com>

drivers/mbox/CMakeLists.txt

@@ -18,3 +18,4 @@ zephyr_library_sources_ifdef(CONFIG_MBOX_NRF_VEVIF_EVENT_TX mbox_nrf_vevif_event
 zephyr_library_sources_ifdef(CONFIG_MBOX_NRF_BELLBOARD_RX mbox_nrf_bellboard_rx.c)
 zephyr_library_sources_ifdef(CONFIG_MBOX_NRF_BELLBOARD_TX mbox_nrf_bellboard_tx.c)
 zephyr_library_sources_ifdef(CONFIG_MBOX_STM32_HSEM   mbox_stm32_hsem.c)
+zephyr_library_sources_ifdef(CONFIG_MBOX_IVSHMEM mbox_ivshmem.c)

drivers/mbox/Kconfig

@@ -22,7 +22,7 @@ source "drivers/mbox/Kconfig.nrf_vevif_event"
 source "drivers/mbox/Kconfig.nrf_bellboard"
 source "drivers/mbox/Kconfig.stm32_hsem"
 source "drivers/mbox/Kconfig.esp32"
-
+source "drivers/mbox/Kconfig.ivshmem"
 
 config MBOX_INIT_PRIORITY
 	int "MBOX init priority"

drivers/mbox/Kconfig.ivshmem

@@ -0,0 +1,27 @@
+# Copyright (c) 2024, Felipe Neves
+# SPDX-License-Identifier: Apache-2.0
+
+config MBOX_IVSHMEM
+	bool "MBOX driver based on IVSHMEM-Doorbell"
+	default y
+	depends on DT_HAS_LINARO_IVSHMEM_MBOX_ENABLED
+	depends on IVSHMEM
+	depends on IVSHMEM_DOORBELL
+	help
+	  Mailbox driver using IVSHMEM Doorbell mechanism.
+
+if MBOX_IVSHMEM
+
+config MBOX_IVSHMEM_EVENT_LOOP_STACK_SIZE
+	int "Stack size in bytes of IVSHMEM MBOX Event loop task"
+	default 8192
+	help
+	  Adjust the stack size, in bytes of the ivshmem event loop task.
+
+config MBOX_IVSHMEM_EVENT_LOOP_PRIO
+	int "Priority of IVSHMEM MBOX Event loop task"
+	default 2
+	help
+	  Adjust the priority of the ivshmem event loop task.
+
+endif

drivers/mbox/mbox_ivshmem.c

@@ -0,0 +1,155 @@
+/*
+ * Copyright (c) 2024 Felipe Neves.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT linaro_ivshmem_mbox
+
+#include <stdint.h>
+#include <string.h>
+#include <zephyr/device.h>
+#include <zephyr/drivers/mbox.h>
+#include <zephyr/drivers/virtualization/ivshmem.h>
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(mbox_ivshmem, CONFIG_MBOX_LOG_LEVEL);
+
+K_THREAD_STACK_DEFINE(ivshmem_ev_loop_stack, CONFIG_MBOX_IVSHMEM_EVENT_LOOP_STACK_SIZE);
+static struct k_thread ivshmem_ev_loop_thread;
+
+struct ivshmem_mbox_data {
+	mbox_callback_t cb;
+	void *user_data;
+};
+
+struct ivshmem_mbox_config {
+	const struct device *ivshmem_dev;
+	int peer_id;
+};
+
+static void ivshmem_mbox_event_loop_thread(void *arg, void *p2, void *p3)
+{
+	ARG_UNUSED(p2);
+	ARG_UNUSED(p3);
+
+	unsigned int poll_signaled;
+	int ivshmem_vector_rx;
+	struct k_poll_signal sig;
+	struct k_poll_event events[] = {
+		K_POLL_EVENT_INITIALIZER(K_POLL_TYPE_SIGNAL, K_POLL_MODE_NOTIFY_ONLY, &sig),
+	};
+
+	const struct device *dev = (const struct device *)arg;
+	struct ivshmem_mbox_data *dev_data = (struct ivshmem_mbox_data *)dev->data;
+	struct ivshmem_mbox_config *dev_cfg = (struct ivshmem_mbox_config *)dev->config;
+
+	k_poll_signal_init(&sig);
+	int ret = ivshmem_register_handler(dev_cfg->ivshmem_dev, &sig, 0);
+
+	if (ret < 0) {
+		LOG_ERR("registering handlers must be supported: %d\n", ret);
+		k_panic();
+	}
+
+	while (1) {
+		LOG_DBG("%s: waiting interrupt from client...\n", __func__);
+		ret = k_poll(events, ARRAY_SIZE(events), K_FOREVER);
+
+		k_poll_signal_check(&sig, &poll_signaled, &ivshmem_vector_rx);
+		/* get ready for next signal */
+		k_poll_signal_reset(&sig);
+
+		if (dev_data->cb) {
+			dev_data->cb(dev, 0, dev_data->user_data, NULL);
+		}
+	}
+}
+
+static int ivshmem_mbox_send(const struct device *dev, mbox_channel_id_t channel,
+			     const struct mbox_msg *msg)
+{
+	ARG_UNUSED(msg);
+	ARG_UNUSED(channel);
+
+	struct ivshmem_mbox_config *dev_cfg = (struct ivshmem_mbox_config *)dev->config;
+
+	LOG_DBG("sending notification to the peer id 0x%x\n", (int)channel);
+	return ivshmem_int_peer(dev_cfg->ivshmem_dev, (int)channel, 0);
+}
+
+static int ivshmem_mbox_register_callback(const struct device *dev, mbox_channel_id_t channel,
+					  mbox_callback_t cb, void *user_data)
+{
+	ARG_UNUSED(channel);
+
+	struct ivshmem_mbox_data *dev_data = (struct ivshmem_mbox_data *)dev->data;
+
+	if (!cb) {
+		LOG_ERR("Must provide a callback");
+		return -EINVAL;
+	}
+
+	dev_data->cb = cb;
+	dev_data->user_data = user_data;
+
+	return 0;
+}
+
+/* some subsystems needs those functions to be at least implemented,
+ * returning some valid values instead of errors, just provide them.
+ */
+
+static int ivshmem_mbox_mtu_get(const struct device *dev)
+{
+	ARG_UNUSED(dev);
+
+	return 0;
+}
+
+static uint32_t ivshmem_mbox_max_channels_get(const struct device *dev)
+{
+	ARG_UNUSED(dev);
+
+	return UINT16_MAX;
+}
+
+static int ivshmem_mbox_set_enabled(const struct device *dev, mbox_channel_id_t channel,
+				    bool enable)
+{
+	ARG_UNUSED(dev);
+	ARG_UNUSED(channel);
+	ARG_UNUSED(enable);
+
+	return 0;
+}
+
+static int ivshmem_mbox_init(const struct device *dev)
+{
+	k_thread_create(&ivshmem_ev_loop_thread, ivshmem_ev_loop_stack,
+			CONFIG_MBOX_IVSHMEM_EVENT_LOOP_STACK_SIZE, ivshmem_mbox_event_loop_thread,
+			(void *)dev, NULL, NULL, CONFIG_MBOX_IVSHMEM_EVENT_LOOP_PRIO, 0, K_NO_WAIT);
+
+	return 0;
+}
+
+static const struct mbox_driver_api ivshmem_mbox_driver_api = {
+	.send = ivshmem_mbox_send,
+	.register_callback = ivshmem_mbox_register_callback,
+	.mtu_get = ivshmem_mbox_mtu_get,
+	.max_channels_get = ivshmem_mbox_max_channels_get,
+	.set_enabled = ivshmem_mbox_set_enabled,
+};
+
+#define MBOX_IVSHMEM_INIT(inst)                                                            \
+	static const struct ivshmem_mbox_config ivshmem_mbox_cfg_##inst = {                \
+		.ivshmem_dev = DEVICE_DT_GET(DT_INST_PHANDLE(inst, ivshmem)),              \
+	};                                                                                 \
+	static struct ivshmem_mbox_data ivshmem_mbox_data_##inst = {                       \
+		.cb = NULL,                                                                \
+		.user_data = NULL,                                                         \
+	};                                                                                 \
+	DEVICE_DT_INST_DEFINE(inst, ivshmem_mbox_init, NULL, &ivshmem_mbox_data_##inst,    \
+			      &ivshmem_mbox_cfg_##inst, POST_KERNEL,                       \
+			      CONFIG_APPLICATION_INIT_PRIORITY, &ivshmem_mbox_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(MBOX_IVSHMEM_INIT);

dts/bindings/mbox/linaro,ivshmem-mbox.yaml

@@ -0,0 +1,15 @@
+# Copyright (c) 2024 Felipe Neves
+# SPDX-License-Identifier: Apache-2.0
+
+description: Inter VM shared memory based mailbox binding
+
+compatible: "linaro,ivshmem-mbox"
+
+include: base.yaml
+
+properties:
+
+  ivshmem:
+    type: phandle
+    required: true
+    description: ivshmem device node