/*
 * This driver creates fake I2C buses which can contain emulated devices,
 * implemented by a separate emulation driver. The API between this driver and
 * its emulators is defined by struct i2c_emul_driver_api.
 *
 * Copyright 2020 Google LLC
 * Copyright (c) 2020 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#define DT_DRV_COMPAT zephyr_i2c_emul_controller

#define LOG_LEVEL CONFIG_I2C_LOG_LEVEL
#include <logging/log.h>
LOG_MODULE_REGISTER(i2c_emul_ctlr);

#include <device.h>
#include <drivers/emul.h>
#include <drivers/i2c.h>
#include <drivers/i2c_emul.h>

/** Working data for the device */
struct i2c_emul_data {
	/* List of struct i2c_emul associated with the device */
	sys_slist_t emuls;
	/* I2C host configuration */
	uint32_t config;
};

/**
 * Find an emulator by its I2C address
 *
 * @param dev I2C emulation controller device
 * @param addr I2C address of that device
 * @return emulator ro use
 * @return NULL if not found
 */
static struct i2c_emul *i2c_emul_find(const struct device *dev, int addr)
{
	struct i2c_emul_data *data = dev->data;
	sys_snode_t *node;

	SYS_SLIST_FOR_EACH_NODE(&data->emuls, node) {
		struct i2c_emul *emul = NULL;

		emul = CONTAINER_OF(node, struct i2c_emul, node);
		if (emul->addr == addr) {
			return emul;
		}
	}

	return NULL;
}

static int i2c_emul_configure(const struct device *dev, uint32_t dev_config)
{
	struct i2c_emul_data *data = dev->data;

	data->config = dev_config;

	return 0;
}

static int i2c_emul_get_config(const struct device *dev, uint32_t *dev_config)
{
	struct i2c_emul_data *data = dev->data;

	if (data->config == -1) {
		return -EIO;
	}

	*dev_config = data->config;

	return 0;
}

static int i2c_emul_transfer(const struct device *dev, struct i2c_msg *msgs,
			     uint8_t num_msgs, uint16_t addr)
{
	struct i2c_emul *emul;
	const struct i2c_emul_api *api;
	int ret;

	emul = i2c_emul_find(dev, addr);
	if (!emul) {
		return -EIO;
	}

	api = emul->api;
	__ASSERT_NO_MSG(emul->api);
	__ASSERT_NO_MSG(emul->api->transfer);

	ret = api->transfer(emul, msgs, num_msgs, addr);
	if (ret) {
		return ret;
	}

	return 0;
}

/**
 * Set up a new emulator and add it to the list
 *
 * @param dev I2C emulation controller device
 */
static int i2c_emul_init(const struct device *dev)
{
	struct i2c_emul_data *data = dev->data;
	const struct emul_list_for_bus *list = dev->config;
	int rc;

	sys_slist_init(&data->emuls);

	rc = emul_init_for_bus_from_list(dev, list);

	/* Set config to an uninitialized state */
	data->config = -1;

	return rc;
}

int i2c_emul_register(const struct device *dev, const char *name,
		      struct i2c_emul *emul)
{
	struct i2c_emul_data *data = dev->data;

	sys_slist_append(&data->emuls, &emul->node);

	LOG_INF("Register emulator '%s' at I2C addr %02x\n", name, emul->addr);

	return 0;
}

/* Device instantiation */

static struct i2c_driver_api i2c_emul_api = {
	.configure = i2c_emul_configure,
	.get_config = i2c_emul_get_config,
	.transfer = i2c_emul_transfer,
};

#define EMUL_LINK_AND_COMMA(node_id) {		\
	.label = DT_LABEL(node_id),		\
},

#define I2C_EMUL_INIT(n) \
	static const struct emul_link_for_bus emuls_##n[] = { \
		DT_FOREACH_CHILD(DT_DRV_INST(n), EMUL_LINK_AND_COMMA) \
	}; \
	static struct emul_list_for_bus i2c_emul_cfg_##n = { \
		.children = emuls_##n, \
		.num_children = ARRAY_SIZE(emuls_##n), \
	}; \
	static struct i2c_emul_data i2c_emul_data_##n; \
	I2C_DEVICE_DT_INST_DEFINE(n, \
			    i2c_emul_init, \
			    NULL, \
			    &i2c_emul_data_##n, \
			    &i2c_emul_cfg_##n, \
			    POST_KERNEL, \
			    CONFIG_I2C_INIT_PRIORITY, \
			    &i2c_emul_api);

DT_INST_FOREACH_STATUS_OKAY(I2C_EMUL_INIT)