/****************************************************************************
*
* Copyright (C) 2012 PX4 Development Team. All rights reserved.
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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
* 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
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*
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/**
* @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
