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/**
 * @file fxas21002c_i2c.cpp
 *
 * Driver for the NXP FXAS21002C connected via I2C.
 *
 * @author Robert Fu
 */
#include <drivers/device/i2c.h>
#include "FXAS21002C.hpp"

device::Device *FXAS21002C_I2C_interface(int bus, int bus_frequenc, int i2c_addressy);

class FXAS21002C_I2C : public device::I2C
{
public:
	FXAS21002C_I2C(int bus, int bus_frequency, int i2c_address);
	~FXAS21002C_I2C() override = default;

	/**
	 * Read directly from the device.
	 *
	 * The actual size of each unit quantity is device-specific.
	 *
	 * @param reg	The register address at which to start reading
	 * @param data	The buffer into which the read values should be placed.
	 * @param count	The number of items to read.
	 * @return		The number of items read on success, negative errno otherwise.
	 */
	int	read(unsigned reg, void *data, unsigned count) override;

	/**
	 * Write directly to the device.
	 *
	 * The actual size of each unit quantity is device-specific.
	 *
	 * @param reg	The register address at which to start writing.
	 * @param data	The buffer from which values should be read.
	 * @param count	The number of items to write.
	 * @return		The number of items written on success, negative errno otherwise.
	 */
	int	write(unsigned reg, void *data, unsigned count) override;

	/**
	 * Read a register from the device.
	 *
	 * @param		The register to read.
	 * @return		The value that was read.
	 */
	uint8_t read_reg(unsigned reg) override;

	/**
	 * Write a register in the device.
	 *
	 * @param reg		The register to write.
	 * @param value		The new value to write.
	 * @return		OK on success, negative errno otherwise.
	 */
	int write_reg(unsigned reg, uint8_t value) override;

protected:
	int probe() override;
};

device::Device *
FXAS21002C_I2C_interface(int bus, int bus_frequency, int i2c_address)
{
	return new FXAS21002C_I2C(bus, bus_frequency, i2c_address);
}

FXAS21002C_I2C::FXAS21002C_I2C(int bus, int bus_frequency, int i2c_address) :
	I2C(DRV_GYR_DEVTYPE_FXAS2100C, MODULE_NAME, bus, i2c_address, bus_frequency)
{
}

int
FXAS21002C_I2C::probe()
{
	uint8_t whoami = read_reg(FXAS21002C_WHO_AM_I);
	bool success = (whoami == WHO_AM_I);

	return success ? OK : -EIO;
}

/**
 * Read directly from the device.
 *
 * The actual size of each unit quantity is device-specific.
 *
 * @param reg	The register address at which to start reading
 * @param data	The buffer into which the read values should be placed.
 * @param count	The number of items to read.
 * @return		The number of items read on success, negative errno otherwise.
 */
int FXAS21002C_I2C::read(unsigned reg, void *data, unsigned count)
{
	/* Same as in mpu9250_i2c.cpp:
	 * We want to avoid copying the data of RawGyroReport: So if the caller
	 * supplies a buffer not RawGyroReport in size, it is assume to be a reg or
	 * reg 16 read
	 * Since RawGyroReport has a cmd at front, we must return the data
	 * after that. Foe anthing else we must return it
	 */
	uint32_t offset = count < sizeof(RawGyroReport) ? 0 : offsetof(RawGyroReport, status);
	uint8_t cmd = FXAS21002C_REG(reg);

	return transfer(&cmd, 1, &((uint8_t *)data)[offset], count - offset);
}

/**
 * Write directly to the device.
 *
 * The actual size of each unit quantity is device-specific.
 *
 * @param reg	The register address at which to start writing.
 * @param data	The buffer from which values should be read.
 * @param count	The number of items to write.
 * @return		The number of items written on success, negative errno otherwise.
 */
int FXAS21002C_I2C::write(unsigned reg, void *data, unsigned count)
{
	uint8_t cmd[2];

	if (sizeof(cmd) < (count + 1)) {
		// same as in mpu9250_i2c.cpp
		// This condition means only supportting the case of count == 1
		// so this API is the same as write_reg
		return -EIO;
	}

	cmd[0] = FXAS21002C_REG(reg);
	cmd[1] = *(uint8_t *)data;

	return transfer(cmd, sizeof(cmd), nullptr, 0);
}

/**
 * Read a register from the device.
 *
 * @param		The register to read.
 * @return		The value that was read.
 */
uint8_t FXAS21002C_I2C::read_reg(unsigned reg)
{
	uint8_t cmd[1];
	uint8_t data[1];

	cmd[0] = reg & 0x00FF;

	transfer(cmd, 1, data, 1);

	return data[0];
}

/**
 * Write a register in the device.
 *
 * @param reg		The register to write.
 * @param value		The new value to write.
 * @return		OK on success, negative errno otherwise.
 */
int FXAS21002C_I2C::write_reg(unsigned reg, uint8_t value)
{
	uint8_t cmd[2];

	cmd[0] = reg & 0x00FF;
	cmd[1] = value;

	return transfer(cmd, 2, nullptr, 0);
}