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Diffstat (limited to 'src/drivers/device/i2c.cpp')
| -rw-r--r-- | src/drivers/device/i2c.cpp | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/src/drivers/device/i2c.cpp b/src/drivers/device/i2c.cpp new file mode 100644 index 000000000..a416801eb --- /dev/null +++ b/src/drivers/device/i2c.cpp @@ -0,0 +1,204 @@ +/**************************************************************************** + * + * 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 i2c.cpp + * + * Base class for devices attached via the I2C bus. + * + * @todo Bus frequency changes; currently we do nothing with the value + * that is supplied. Should we just depend on the bus knowing? + */ + +#include "i2c.h" + +namespace device +{ + +I2C::I2C(const char *name, + const char *devname, + int bus, + uint16_t address, + uint32_t frequency, + int irq) : + // base class + CDev(name, devname, irq), + // public + // protected + _retries(0), + // private + _bus(bus), + _address(address), + _frequency(frequency), + _dev(nullptr) +{ +} + +I2C::~I2C() +{ + if (_dev) + up_i2cuninitialize(_dev); +} + +int +I2C::init() +{ + int ret = OK; + + /* attach to the i2c bus */ + _dev = up_i2cinitialize(_bus); + + if (_dev == nullptr) { + debug("failed to init I2C"); + ret = -ENOENT; + goto out; + } + + // 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 device node, etc + ret = CDev::init(); + + if (ret != OK) { + debug("cdev init failed"); + goto out; + } + + // tell the world where we are + log("on I2C bus %d at 0x%02x", _bus, _address); + +out: + return ret; +} + +int +I2C::probe() +{ + // Assume the device is too stupid to be discoverable. + return OK; +} + +int +I2C::transfer(const uint8_t *send, unsigned send_len, uint8_t *recv, unsigned recv_len) +{ + struct i2c_msg_s msgv[2]; + unsigned msgs; + int ret; + unsigned retry_count = 0; + + do { + // debug("transfer out %p/%u in %p/%u", send, send_len, recv, recv_len); + + msgs = 0; + + if (send_len > 0) { + msgv[msgs].addr = _address; + msgv[msgs].flags = 0; + msgv[msgs].buffer = const_cast<uint8_t *>(send); + msgv[msgs].length = send_len; + msgs++; + } + + if (recv_len > 0) { + msgv[msgs].addr = _address; + msgv[msgs].flags = I2C_M_READ; + msgv[msgs].buffer = recv; + msgv[msgs].length = recv_len; + msgs++; + } + + if (msgs == 0) + return -EINVAL; + + /* + * I2C architecture means there is an unavoidable race here + * if there are any devices on the bus with a different frequency + * preference. Really, this is pointless. + */ + I2C_SETFREQUENCY(_dev, _frequency); + ret = I2C_TRANSFER(_dev, &msgv[0], msgs); + + /* success */ + if (ret == OK) + break; + + /* if we have already retried once, or we are going to give up, then reset the bus */ + if ((retry_count >= 1) || (retry_count >= _retries)) + up_i2creset(_dev); + + } while (retry_count++ < _retries); + + return ret; + +} + +int +I2C::transfer(i2c_msg_s *msgv, unsigned msgs) +{ + int ret; + unsigned retry_count = 0; + + /* force the device address into the message vector */ + for (unsigned i = 0; i < msgs; i++) + msgv[i].addr = _address; + + + do { + /* + * I2C architecture means there is an unavoidable race here + * if there are any devices on the bus with a different frequency + * preference. Really, this is pointless. + */ + I2C_SETFREQUENCY(_dev, _frequency); + ret = I2C_TRANSFER(_dev, msgv, msgs); + + /* success */ + if (ret == OK) + break; + + /* if we have already retried once, or we are going to give up, then reset the bus */ + if ((retry_count >= 1) || (retry_count >= _retries)) + up_i2creset(_dev); + + } while (retry_count++ < _retries); + + return ret; +} + +} // namespace device
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