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#include "IST8308.hpp"

using namespace time_literals;

static constexpr int16_t combine(uint8_t msb, uint8_t lsb)
{
	return (msb << 8u) | lsb;
}

IST8308::IST8308(I2CSPIBusOption bus_option, int bus, int bus_frequency, enum Rotation rotation) :
	I2C(DRV_MAG_DEVTYPE_IST8308, MODULE_NAME, bus, I2C_ADDRESS_DEFAULT, bus_frequency),
	I2CSPIDriver(MODULE_NAME, px4::device_bus_to_wq(get_device_id()), bus_option, bus),
	_px4_mag(get_device_id(), rotation)
{
	_px4_mag.set_external(external());
}

IST8308::~IST8308()
{
	perf_free(_reset_perf);
	perf_free(_bad_register_perf);
	perf_free(_bad_transfer_perf);
}

int IST8308::init()
{
	int ret = I2C::init();

	if (ret != PX4_OK) {
		DEVICE_DEBUG("I2C::init failed (%i)", ret);
		return ret;
	}

	return Reset() ? 0 : -1;
}

bool IST8308::Reset()
{
	_state = STATE::RESET;
	ScheduleClear();
	ScheduleNow();
	return true;
}

void IST8308::print_status()
{
	I2CSPIDriverBase::print_status();

	perf_print_counter(_reset_perf);
	perf_print_counter(_bad_register_perf);
	perf_print_counter(_bad_transfer_perf);
}

int IST8308::probe()
{
	_retries = 2;

	for (int retry = 0; retry < 3; retry++) {
		const uint8_t WAI = RegisterRead(Register::WAI);

		if (WAI == Device_ID) {
			return PX4_OK;

		} else {
			DEVICE_DEBUG("unexpected WAI 0x%02x", WAI);
		}
	}

	return PX4_ERROR;
}

void IST8308::RunImpl()
{
	const hrt_abstime now = hrt_absolute_time();

	switch (_state) {
	case STATE::RESET:
		// CNTL3: Software Reset
		RegisterWrite(Register::CNTL3, CNTL3_BIT::SRST);
		_reset_timestamp = now;
		_failure_count = 0;
		_state = STATE::WAIT_FOR_RESET;
		perf_count(_reset_perf);
		ScheduleDelayed(50_ms); // Power On Reset: max 50ms
		break;

	case STATE::WAIT_FOR_RESET:

		// Register::CNTL3 SRST: This bit is automatically reset to zero after POR routine
		if ((RegisterRead(Register::WAI) == Device_ID)
		    && ((RegisterRead(Register::CNTL3) & CNTL3_BIT::SRST) == 0)) {

			// if reset succeeded then configure
			_state = STATE::CONFIGURE;
			ScheduleDelayed(10_ms);

		} else {
			// RESET not complete
			if (hrt_elapsed_time(&_reset_timestamp) > 1000_ms) {
				PX4_DEBUG("Reset failed, retrying");
				_state = STATE::RESET;
				ScheduleDelayed(100_ms);

			} else {
				PX4_DEBUG("Reset not complete, check again in 10 ms");
				ScheduleDelayed(10_ms);
			}
		}

		break;

	case STATE::CONFIGURE:
		if (Configure()) {
			// if configure succeeded then start reading every 20 ms (50 Hz)
			_state = STATE::READ;
			ScheduleOnInterval(20_ms, 20_ms);

		} else {
			// CONFIGURE not complete
			if (hrt_elapsed_time(&_reset_timestamp) > 1000_ms) {
				PX4_DEBUG("Configure failed, resetting");
				_state = STATE::RESET;

			} else {
				PX4_DEBUG("Configure failed, retrying");
			}

			ScheduleDelayed(100_ms);
		}

		break;

	case STATE::READ: {
			struct TransferBuffer {
				uint8_t STAT;
				uint8_t DATAXL;
				uint8_t DATAXH;
				uint8_t DATAYL;
				uint8_t DATAYH;
				uint8_t DATAZL;
				uint8_t DATAZH;
			} buffer{};

			bool success = false;
			uint8_t cmd = static_cast<uint8_t>(Register::STAT);

			if (transfer(&cmd, 1, (uint8_t *)&buffer, sizeof(buffer)) == PX4_OK) {

				if (buffer.STAT & STAT_BIT::DRDY) {
					int16_t x = combine(buffer.DATAXH, buffer.DATAXL);
					int16_t y = combine(buffer.DATAYH, buffer.DATAYL);
					int16_t z = combine(buffer.DATAZH, buffer.DATAZL);

					// sensor's frame is +x forward, +y right, +z up
					z = (z == INT16_MIN) ? INT16_MAX : -z; // flip z

					_px4_mag.set_error_count(perf_event_count(_bad_register_perf) + perf_event_count(_bad_transfer_perf));
					_px4_mag.update(now, x, y, z);

					success = true;

					if (_failure_count > 0) {
						_failure_count--;
					}
				}

			} else {
				perf_count(_bad_transfer_perf);
			}

			if (!success) {
				_failure_count++;

				// full reset if things are failing consistently
				if (_failure_count > 10) {
					Reset();
					return;
				}
			}

			if (!success || hrt_elapsed_time(&_last_config_check_timestamp) > 100_ms) {
				// check configuration registers periodically or immediately following any failure
				if (RegisterCheck(_register_cfg[_checked_register])) {
					_last_config_check_timestamp = now;
					_checked_register = (_checked_register + 1) % size_register_cfg;

				} else {
					// register check failed, force reset
					perf_count(_bad_register_perf);
					Reset();
				}
			}
		}

		break;
	}
}

bool IST8308::Configure()
{
	// first set and clear all configured register bits
	for (const auto &reg_cfg : _register_cfg) {
		RegisterSetAndClearBits(reg_cfg.reg, reg_cfg.set_bits, reg_cfg.clear_bits);
	}

	// now check that all are configured
	bool success = true;

	for (const auto &reg_cfg : _register_cfg) {
		if (!RegisterCheck(reg_cfg)) {
			success = false;
		}
	}

	// 1 Microtesla = 0.01 Gauss
	_px4_mag.set_scale(1.f / 13.2f * 0.01f); // 13.2 LSB/uT

	return success;
}

bool IST8308::RegisterCheck(const register_config_t &reg_cfg)
{
	bool success = true;

	const uint8_t reg_value = RegisterRead(reg_cfg.reg);

	if (reg_cfg.set_bits && ((reg_value & reg_cfg.set_bits) != reg_cfg.set_bits)) {
		PX4_DEBUG("0x%02hhX: 0x%02hhX (0x%02hhX not set)", (uint8_t)reg_cfg.reg, reg_value, reg_cfg.set_bits);
		success = false;
	}

	if (reg_cfg.clear_bits && ((reg_value & reg_cfg.clear_bits) != 0)) {
		PX4_DEBUG("0x%02hhX: 0x%02hhX (0x%02hhX not cleared)", (uint8_t)reg_cfg.reg, reg_value, reg_cfg.clear_bits);
		success = false;
	}

	return success;
}

uint8_t IST8308::RegisterRead(Register reg)
{
	const uint8_t cmd = static_cast<uint8_t>(reg);
	uint8_t buffer{};
	transfer(&cmd, 1, &buffer, 1);
	return buffer;
}

void IST8308::RegisterWrite(Register reg, uint8_t value)
{
	uint8_t buffer[2] { (uint8_t)reg, value };
	transfer(buffer, sizeof(buffer), nullptr, 0);
}

void IST8308::RegisterSetAndClearBits(Register reg, uint8_t setbits, uint8_t clearbits)
{
	const uint8_t orig_val = RegisterRead(reg);
	uint8_t val = (orig_val & ~clearbits) | setbits;

	if (orig_val != val) {
		RegisterWrite(reg, val);
	}
}