/****************************************************************************
 *
 *   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
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 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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 ****************************************************************************/

/**
 * @file spi.cpp
 *
 * Base class for devices connected via SPI.
 *
 * @todo Work out if caching the mode/frequency would save any time.
 *
 * @todo A separate bus/device abstraction would allow for mixed interrupt-mode
 * and non-interrupt-mode clients to arbitrate for the bus.  As things stand,
 * a bus shared between clients of both kinds is vulnerable to races between
 * the two, where an interrupt-mode client will ignore the lock held by the
 * non-interrupt-mode client.
 */

#include <nuttx/arch.h>

#include "spi.h"

#ifndef CONFIG_SPI_EXCHANGE
# error This driver requires CONFIG_SPI_EXCHANGE
#endif

namespace device
{

SPI::SPI(const char *name,
	 const char *devname,
	 int bus,
	 enum spi_dev_e device,
	 enum spi_mode_e mode,
	 uint32_t frequency,
	 int irq) :
	// base class
	CDev(name, devname, irq),
	// public
	// protected
	locking_mode(LOCK_PREEMPTION),
	// private
	_bus(bus),
	_device(device),
	_mode(mode),
	_frequency(frequency),
	_dev(nullptr)
{
}

SPI::~SPI()
{
	// XXX no way to let go of the bus...
}

int
SPI::init()
{
	int ret = OK;

	/* attach to the spi bus */
	if (_dev == nullptr)
		_dev = up_spiinitialize(_bus);

	if (_dev == nullptr) {
		debug("failed to init SPI");
		ret = -ENOENT;
		goto out;
	}

	/* deselect device to ensure high to low transition of pin select */
	SPI_SELECT(_dev, _device, false);

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

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

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

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

	/* tell the workd where we are */
	log("on SPI bus %d at %d", _bus, _device);

out:
	return ret;
}

int
SPI::probe()
{
	// assume the device is too stupid to be discoverable
	return OK;
}

int
SPI::transfer(uint8_t *send, uint8_t *recv, unsigned len)
{
	irqstate_t	state;

	if ((send == nullptr) && (recv == nullptr))
		return -EINVAL;

	/* lock the bus as required */
	if (!up_interrupt_context()) {
		switch (locking_mode) {
		default:
		case LOCK_PREEMPTION:
			state = irqsave();
			break;
		case LOCK_THREADS:
			SPI_LOCK(_dev, true);
			break;
		case LOCK_NONE:
			break;
		}
	}

	SPI_SETFREQUENCY(_dev, _frequency);
	SPI_SETMODE(_dev, _mode);
	SPI_SETBITS(_dev, 8);
	SPI_SELECT(_dev, _device, true);

	/* do the transfer */
	SPI_EXCHANGE(_dev, send, recv, len);

	/* and clean up */
	SPI_SELECT(_dev, _device, false);

	if (!up_interrupt_context()) {
		switch (locking_mode) {
		default:
		case LOCK_PREEMPTION:
			irqrestore(state);
			break;
		case LOCK_THREADS:
			SPI_LOCK(_dev, false);
			break;
		case LOCK_NONE:
			break;
		}
	}

	return OK;
}

} // namespace device