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/****************************************************************************
*
* 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
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @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
_device(device),
_mode(mode),
_frequency(frequency),
_dev(nullptr),
_bus(bus)
{
// fill in _device_id fields for a SPI device
_device_id.devid_s.bus_type = DeviceBusType_SPI;
_device_id.devid_s.bus = bus;
_device_id.devid_s.address = (uint8_t)device;
// devtype needs to be filled in by the driver
_device_id.devid_s.devtype = 0;
}
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)
{
int result;
if ((send == nullptr) && (recv == nullptr))
return -EINVAL;
LockMode mode = up_interrupt_context() ? LOCK_NONE : locking_mode;
/* lock the bus as required */
switch (mode) {
default:
case LOCK_PREEMPTION:
{
irqstate_t state = irqsave();
result = _transfer(send, recv, len);
irqrestore(state);
}
break;
case LOCK_THREADS:
SPI_LOCK(_dev, true);
result = _transfer(send, recv, len);
SPI_LOCK(_dev, false);
break;
case LOCK_NONE:
result = _transfer(send, recv, len);
break;
}
return result;
}
void
SPI::set_frequency(uint32_t frequency)
{
_frequency = frequency;
}
int
SPI::_transfer(uint8_t *send, uint8_t *recv, unsigned len)
{
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);
return OK;
}
} // namespace device
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