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 *
 *   Copyright (c) 2016-2020 PX4 Development Team. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name PX4 nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
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/**
 * @file I2C.cpp
 *
 * Base class for devices attached via the I2C bus.
 *
 * @todo Bus frequency changes; currently we do nothing with the value
 *       that is supplied.  Should we just depend on the bus knowing?
 */

#include "I2C.hpp"

#ifdef __PX4_LINUX

#include <linux/i2c.h>
#include <linux/i2c-dev.h>

namespace device
{

I2C::I2C(uint8_t device_type, const char *name, const int bus, const uint16_t address, const uint32_t frequency) :
	CDev(name, nullptr)
{
	// fill in _device_id fields for a I2C device
	_device_id.devid_s.devtype = device_type;
	_device_id.devid_s.bus_type = DeviceBusType_I2C;
	_device_id.devid_s.bus = bus;
	_device_id.devid_s.address = address;
}

I2C::~I2C()
{
	if (_fd >= 0) {
		::close(_fd);
		_fd = -1;
	}
}

int
I2C::init()
{
	int ret = PX4_ERROR;

	// Open the actual I2C device
	char dev_path[16] {};
	snprintf(dev_path, sizeof(dev_path), "/dev/i2c-%i", get_device_bus());
	_fd = ::open(dev_path, O_RDWR);

	if (_fd < 0) {
		DEVICE_DEBUG("failed to init I2C");
		ret = -ENOENT;
		goto out;
	}

	// call the probe function to check whether the device is present
	ret = probe();

	if (ret != OK) {
		DEVICE_DEBUG("probe failed");
		goto out;
	}

	// do base class init, which will create device node, etc
	ret = CDev::init();

	if (ret != OK) {
		DEVICE_DEBUG("cdev init failed");
		goto out;
	}

	// tell the world where we are
	DEVICE_DEBUG("on I2C bus %d at 0x%02x", get_device_bus(), get_device_address());

out:

	if ((ret != OK) && !(_fd < 0)) {
		::close(_fd);
		_fd = -1;
	}

	return ret;
}

int
I2C::transfer(const uint8_t *send, const unsigned send_len, uint8_t *recv, const unsigned recv_len)
{
	int ret = PX4_ERROR;
	unsigned retry_count = 0;

	if (_fd < 0) {
		PX4_ERR("I2C device not opened");
		return PX4_ERROR;
	}

	do {
		DEVICE_DEBUG("transfer out %p/%u  in %p/%u", send, send_len, recv, recv_len);

		unsigned msgs = 0;
		struct i2c_msg msgv[2] {};

		if (send_len > 0) {
			msgv[msgs].addr = get_device_address();
			msgv[msgs].flags = 0;
			msgv[msgs].buf = const_cast<uint8_t *>(send);
			msgv[msgs].len = send_len;
			msgs++;
		}

		if (recv_len > 0) {
			msgv[msgs].addr = get_device_address();
			msgv[msgs].flags = I2C_M_RD;
			msgv[msgs].buf = recv;
			msgv[msgs].len = recv_len;
			msgs++;
		}

		if (msgs == 0) {
			return -EINVAL;
		}

		i2c_rdwr_ioctl_data packets{};
		packets.msgs  = msgv;
		packets.nmsgs = msgs;

		int ret_ioctl = ::ioctl(_fd, I2C_RDWR, (unsigned long)&packets);

		if (ret_ioctl == -1) {
			DEVICE_DEBUG("I2C transfer failed");
			ret = PX4_ERROR;

		} else {
			// success
			ret = PX4_OK;
			break;
		}

	} while (retry_count++ < _retries);

	return ret;
}

} // namespace device

#endif // __PX4_LINUX
