/****************************************************************************
 *
 *   Copyright (C) 2012 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/**
 * @file spi.h
 *
 * Base class for devices connected via SPI.
 */

#ifndef _DEVICE_SPI_H
#define _DEVICE_SPI_H

#include "device.h"

#include <nuttx/spi.h>

namespace device __EXPORT
{

/**
 * Abstract class for character device on SPI
 */
class __EXPORT SPI : public CDev
{
protected:
	/**
	 * Constructor
	 *
	 * @param name		Driver name
	 * @param devname	Device node name
	 * @param bus		SPI bus on which the device lives
	 * @param device	Device handle (used by SPI_SELECT)
	 * @param mode		SPI clock/data mode
	 * @param frequency	SPI clock frequency
	 * @param irq		Interrupt assigned to the device (or zero if none)
	 */
	SPI(const char *name,
	    const char *devname,
	    int bus,
	    enum spi_dev_e device,
	    enum spi_mode_e mode,
	    uint32_t frequency,
	    int irq = 0);
	virtual ~SPI();

	virtual int	init();

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

	/**
	 * Perform a SPI transfer.
	 *
	 * If called from interrupt context, this interface does not lock
	 * the bus and may interfere with non-interrupt-context callers.
	 *
	 * Clients in a mixed interrupt/non-interrupt configuration must
	 * ensure appropriate interlocking.
	 *
	 * At least one of send or recv must be non-null.
	 *
	 * @param send		Bytes to send to the device, or nullptr if
	 *			no data is to be sent.
	 * @param recv		Buffer for receiving bytes from the device,
	 *			or nullptr if no bytes are to be received.
	 * @param len		Number of bytes to transfer.
	 * @return		OK if the exchange was successful, -errno
	 *			otherwise.
	 */
	int		transfer(uint8_t *send, uint8_t *recv, unsigned len);

	/**
	 * Set the SPI bus frequency
	 * This is used to change frequency on the fly. Some sensors
	 * (such as the MPU6000) need a lower frequency for setup
	 * registers and can handle higher frequency for sensor 
	 * value registers
	 *
	 * @param frequency	Frequency to set (Hz)
	 */
        void		set_frequency(uint32_t frequency);

	/**
	 * Locking modes supported by the driver.
	 */
	enum LockMode {
		LOCK_PREEMPTION,	/**< the default; lock against all forms of preemption. */
		LOCK_THREADS,		/**< lock only against other threads, using SPI_LOCK */
		LOCK_NONE		/**< perform no locking, only safe if the bus is entirely private */
	};

	LockMode	locking_mode;	/**< selected locking mode */

private:
	enum spi_dev_e		_device;
	enum spi_mode_e		_mode;
	uint32_t		_frequency;
	struct spi_dev_s	*_dev;

	/* this class does not allow copying */
	SPI(const SPI&);
	SPI operator=(const SPI&);

protected:
	int			_bus;

	int	_transfer(uint8_t *send, uint8_t *recv, unsigned len);

};

} // namespace device

#endif /* _DEVICE_SPI_H */