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 * modification, are permitted provided that the following conditions
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 *
 * 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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 *    used to endorse or promote products derived from this software
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 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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/**
 * @file SPI.hpp
 *
 * Base class for devices connected via SPI.
 */

#pragma once

#include "../CDev.hpp"

#include "dev_fs_lib_spi.h"

enum spi_mode_e {
	SPIDEV_MODE0 = 0, /* CPOL=0 CHPHA=0 */
	SPIDEV_MODE1 = 1, /* CPOL=0 CHPHA=1 */
	SPIDEV_MODE2 = 2, /* CPOL=1 CHPHA=0 */
	SPIDEV_MODE3 = 3  /* CPOL=1 CHPHA=1 */
};

namespace device __EXPORT
{

/**
 * Abstract class for character device on SPI
 */
class __EXPORT SPI : public CDev
{
protected:
	/**
	 * Constructor
	 *
	 * @param device_type	The device type (see drv_sensor.h)
	 * @param name		Driver 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
	 */
	SPI(uint8_t device_type, const char *name, int bus, uint32_t device, enum spi_mode_e mode, uint32_t frequency);
	virtual ~SPI();

	/**
	 * 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 */
	};

	virtual int	init();

	/**
	 * Check for the presence of the device on the bus.
	 */
	virtual int	probe() { return PX4_OK; }

	/**
	 * 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);

	/**
	 * Perform a SPI 16 bit 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		Words to send to the device, or nullptr if
	 *			no data is to be sent.
	 * @param recv		Words for receiving bytes from the device,
	 *			or nullptr if no bytes are to be received.
	 * @param len		Number of words to transfer.
	 * @return		OK if the exchange was successful, -errno
	 *			otherwise.
	 */
	int		transferhword(uint16_t *send, uint16_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) { _frequency = frequency; }
	uint32_t	get_frequency() { return _frequency; }

	/**
	 * Set the SPI bus locking mode
	 *
	 * This set the SPI locking mode. For devices competing with NuttX SPI
	 * drivers on a bus the right lock mode is LOCK_THREADS.
	 *
	 * @param mode	Locking mode
	 */
	void		set_lockmode(enum LockMode mode) {}

private:
	int 			_fd{-1};

	uint32_t		_device;
	enum spi_mode_e		_mode;
	uint32_t		_frequency;

protected:

	bool	external() { return px4_spi_bus_external(get_device_bus()); }

};

} // namespace device