px4_autopilot/apps/drivers/device/i2c.h

/****************************************************************************
 *
 *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
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 * 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
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 *    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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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/**
 * @file i2c.h
 *
 * Base class for devices connected via I2C.
 */

#ifndef _DEVICE_I2C_H
#define _DEVICE_I2C_H

#include "device.h"

#include <nuttx/i2c.h>

namespace device __EXPORT
{

/**
 * Abstract class for character device on I2C
 */
class __EXPORT I2C : public CDev
{

protected:
	/**
	 * The number of times a read or write operation will be retried on
	 * error.
	 */
	unsigned		_retries;

	/**
	 * @ Constructor
	 *
	 * @param name		Driver name
	 * @param devname	Device node name
	 * @param bus		I2C bus on which the device lives
	 * @param address	I2C bus address, or zero if set_address will be used
	 * @param frequency	I2C bus frequency for the device (currently not used)
	 * @param irq		Interrupt assigned to the device (or zero if none)
	 */
	I2C(const char *name,
	    const char *devname,
	    int bus,
	    uint16_t address,
	    uint32_t frequency,
	    int irq = 0);
	~I2C();

	virtual int	init();

	/**
	 * Check for the presence of the device on the bus.
	 */
	virtual int	probe();

	/**
	 * Perform an I2C transaction to the device.
	 *
	 * At least one of send_len and recv_len must be non-zero.
	 *
	 * @param send		Pointer to bytes to send.
	 * @param send_len	Number of bytes to send.
	 * @param recv		Pointer to buffer for bytes received.
	 * @param recv_len	Number of bytes to receive.
	 * @return		OK if the transfer was successful, -errno
	 *			otherwise.
	 */
	int		transfer(const uint8_t *send, unsigned send_len,
				 uint8_t *recv, unsigned recv_len);

	/**
	 * Perform a multi-part I2C transaction to the device.
	 *
	 * @param msgv		An I2C message vector.
	 * @param msgs		The number of entries in the message vector.
	 * @return		OK if the transfer was successful, -errno
	 *			otherwise.
	 */
	int		transfer(i2c_msg_s *msgv, unsigned msgs);

	/**
	 * Change the bus address.
	 *
	 * Most often useful during probe() when the driver is testing
	 * several possible bus addresses.
	 *
	 * @param address	The new bus address to set.
	 */
	void		set_address(uint16_t address) {
		_address = address;
	}

private:
	int			_bus;
	uint16_t		_address;
	uint32_t		_frequency;
	struct i2c_dev_s	*_dev;
};

} // namespace device

#endif /* _DEVICE_I2C_H */