PX4-Autopilot/src/lib/drivers/device/Device.hpp

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/**
 * @file Device.hpp
 *
 * Definitions for the generic base classes in the device framework.
 */

#ifndef _DEVICE_DEVICE_HPP
#define _DEVICE_DEVICE_HPP

/*
 * Includes here should only cover the needs of the framework definitions.
 */
#include <px4_platform_common/px4_config.h>
#include <px4_platform_common/posix.h>

#include <drivers/drv_sensor.h>

#define DEVICE_LOG(FMT, ...) PX4_LOG_NAMED(_name, FMT, ##__VA_ARGS__)
#define DEVICE_DEBUG(FMT, ...) PX4_LOG_NAMED_COND(_name, _debug_enabled, FMT, ##__VA_ARGS__)

/**
 * Namespace encapsulating all device framework classes, functions and data.
 */
namespace device
{

/**
 * Fundamental base class for all physical drivers (I2C, SPI).
 *
 * This class provides the basic driver template for I2C and SPI devices
 */
class __EXPORT Device
{
public:

	// no copy, assignment, move, move assignment
	Device(const Device &) = delete;
	Device &operator=(const Device &) = delete;
	Device(Device &&) = delete;
	Device &operator=(Device &&) = delete;

	/**
	 * Destructor.
	 *
	 * Public so that anonymous devices can be destroyed.
	 */
	virtual ~Device() = default;

	/*
	 * Direct access methods.
	 */

	/**
	 * Initialise the driver and make it ready for use.
	 *
	 * @return	OK if the driver initialized OK, negative errno otherwise;
	 */
	virtual int	init() { return PX4_OK; }

	/**
	 * Read directly from the device.
	 *
	 * The actual size of each unit quantity is device-specific.
	 *
	 * @param offset	The device 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.
	 */
	virtual int	read(unsigned address, void *data, unsigned count) { return -ENODEV; }

	/**
	 * Write directly to the device.
	 *
	 * The actual size of each unit quantity is device-specific.
	 *
	 * @param address	The device 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.
	 */
	virtual int	write(unsigned address, void *data, unsigned count) { return -ENODEV; }

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

	/**
	 * 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.
	 */
	virtual int write_reg(unsigned reg, uint8_t value) { return -ENODEV; }

	/**
	 * Perform a device-specific operation.
	 *
	 * @param operation	The operation to perform.
	 * @param arg		An argument to the operation.
	 * @return		Negative errno on error, OK or positive value on success.
	 */
	virtual int	ioctl(unsigned operation, unsigned &arg) { return -ENODEV; }

	/** Device bus types for DEVID */
	enum DeviceBusType {
		DeviceBusType_UNKNOWN = 0,
		DeviceBusType_I2C     = 1,
		DeviceBusType_SPI     = 2,
		DeviceBusType_UAVCAN  = 3,
		DeviceBusType_SIMULATION = 4,
		DeviceBusType_SERIAL = 5,
		DeviceBusType_MAVLINK = 6,
	};

	/*
	  broken out device elements. The bitfields are used to keep
	  the overall value small enough to fit in a float accurately,
	  which makes it possible to transport over the MAVLink
	  parameter protocol without loss of information.
	 */
	struct DeviceStructure {
		DeviceBusType bus_type : 3;
		uint8_t bus: 5;    // which instance of the bus type
		uint8_t address;   // address on the bus (eg. I2C address)
		uint8_t devtype;   // device class specific device type
	};

	union DeviceId {
		struct DeviceStructure devid_s;
		uint32_t devid;
	};

	uint32_t get_device_id() const { return _device_id.devid; }

	/**
	 * Return the bus type the device is connected to.
	 *
	 * @return The bus type
	 */
	DeviceBusType get_device_bus_type() const { return _device_id.devid_s.bus_type; }
	void          set_device_bus_type(DeviceBusType bus_type) { _device_id.devid_s.bus_type = bus_type; }

	static const char *get_device_bus_string(DeviceBusType bus)
	{
		switch (bus) {
		case DeviceBusType_I2C:
			return "I2C";

		case DeviceBusType_SPI:
			return "SPI";

		case DeviceBusType_UAVCAN:
			return "UAVCAN";

		case DeviceBusType_SIMULATION:
			return "SIMULATION";

		case DeviceBusType_SERIAL:
			return "SERIAL";

		case DeviceBusType_MAVLINK:
			return "MAVLINK";

		case DeviceBusType_UNKNOWN:
		default:
			return "UNKNOWN";
		}
	}

	/**
	 * Return the bus ID the device is connected to.
	 *
	 * @return The bus ID
	 */
	uint8_t get_device_bus() const { return _device_id.devid_s.bus; }
	void    set_device_bus(uint8_t bus) { _device_id.devid_s.bus = bus; }

	/**
	 * Return the bus address of the device.
	 *
	 * @return The bus address
	 */
	uint8_t	get_device_address() const { return _device_id.devid_s.address; }
	void	set_device_address(int address) { _device_id.devid_s.address = address; }

	/**
	 * Return the device type
	 *
	 * @return The device type
	 */
	uint8_t	get_device_type() const { return _device_id.devid_s.devtype; }
	void	set_device_type(uint8_t devtype) { _device_id.devid_s.devtype = devtype; }

	/**
	 * Print decoded device id string to a buffer.
	 *
	 * @param buffer                        buffer to write to
	 * @param length                        buffer length
	 * @param id	                        The device id.
	 * @param return                        number of bytes written
	 */
	static int device_id_print_buffer(char *buffer, int length, uint32_t id)
	{
		DeviceId dev_id{};
		dev_id.devid = id;

		int num_written = snprintf(buffer, length, "Type: 0x%02X, %s:%d (0x%02X)", dev_id.devid_s.devtype,
					   get_device_bus_string(dev_id.devid_s.bus_type), dev_id.devid_s.bus, dev_id.devid_s.address);

		buffer[length - 1] = 0; // ensure 0-termination

		return num_written;
	}

	virtual bool external() const { return false; }

protected:
	union DeviceId	_device_id {};            	/**< device identifier information */

	const char	*_name{nullptr};		/**< driver name */
	bool		_debug_enabled{false};		/**< if true, debug messages are printed */

	Device() = delete;
	explicit Device(const char *name) : _name(name) {}

	Device(uint8_t devtype, const char *name, DeviceBusType bus_type, uint8_t bus, uint8_t address) : _name(name)
	{
		set_device_type(devtype);
		_device_id.devid_s.bus_type = bus_type;
		_device_id.devid_s.bus = bus;
		set_device_address(address);
	}

};

} // namespace device

#endif /* _DEVICE_DEVICE_HPP */