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Diffstat (limited to 'src/drivers/device/spi.cpp')
| -rw-r--r-- | src/drivers/device/spi.cpp | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/src/drivers/device/spi.cpp b/src/drivers/device/spi.cpp new file mode 100644 index 000000000..8fffd60cb --- /dev/null +++ b/src/drivers/device/spi.cpp @@ -0,0 +1,160 @@ +/**************************************************************************** + * + * 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 + // 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) +{ + + if ((send == nullptr) && (recv == nullptr)) + return -EINVAL; + + /* do common setup */ + if (!up_interrupt_context()) + SPI_LOCK(_dev, true); + + 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()) + SPI_LOCK(_dev, false); + + return OK; +} + +} // namespace device |