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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
{
unsigned int I2C::_bus_clocks[3] = { 100000, 100000, 100000 };
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)
{
// fill in _device_id fields for a I2C device
_device_id.devid_s.bus_type = DeviceBusType_I2C;
_device_id.devid_s.bus = bus;
_device_id.devid_s.address = address;
// devtype needs to be filled in by the driver
_device_id.devid_s.devtype = 0;
}
I2C::~I2C()
{
if (_dev) {
up_i2cuninitialize(_dev);
_dev = nullptr;
}
}
int
I2C::set_bus_clock(unsigned bus, unsigned clock_hz)
{
int index = bus - 1;
if (index < 0 || index >= static_cast<int>(sizeof(_bus_clocks) / sizeof(_bus_clocks[0]))) {
return -EINVAL;
}
if (_bus_clocks[index] > 0) {
// debug("overriding clock of %u with %u Hz\n", _bus_clocks[index], clock_hz);
}
_bus_clocks[index] = clock_hz;
return OK;
}
int
I2C::init()
{
int ret = OK;
unsigned bus_index;
// attach to the i2c bus
_dev = up_i2cinitialize(_bus);
if (_dev == nullptr) {
debug("failed to init I2C");
ret = -ENOENT;
goto out;
}
// the above call fails for a non-existing bus index,
// so the index math here is safe.
bus_index = _bus - 1;
// abort if the max frequency we allow (the frequency we ask)
// is smaller than the bus frequency
if (_bus_clocks[bus_index] > _frequency) {
(void)up_i2cuninitialize(_dev);
_dev = nullptr;
log("FAIL: too slow for bus #%u: %u KHz, device max: %u KHz)",
_bus, _bus_clocks[bus_index] / 1000, _frequency / 1000);
ret = -EINVAL;
goto out;
}
// set the bus frequency on the first access if it has
// not been set yet
if (_bus_clocks[bus_index] == 0) {
_bus_clocks[bus_index] = _frequency;
}
// set frequency for this instance once to the bus speed
// the bus speed is the maximum supported by all devices on the bus,
// as we have to prioritize performance over compatibility.
// If a new device requires a lower clock speed, this has to be
// manually set via "fmu i2c <bus> <clock>" before starting any
// drivers.
// This is necessary as automatically lowering the bus speed
// for maximum compatibility could induce timing issues on
// critical sensors the adopter might be unaware of.
I2C_SETFREQUENCY(_dev, _bus_clocks[bus_index]);
// 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: %u KHz, max: %u KHz)",
_bus, _address, _bus_clocks[bus_index] / 1000, _frequency / 1000);
out:
if ((ret != OK) && (_dev != nullptr)) {
up_i2cuninitialize(_dev);
_dev = nullptr;
}
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;
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 {
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
