PX4模块设计之四十一：I2C/SPI Bus Instance基础知识

Posted lida2003

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PX4模块设计之四十一：I2C/SPI Bus Instance基础知识

1. 基础知识

  1. ListNode类
  2. List类
  3. BusCLIArguments类
  4. BusInstanceIterator类
  5. I2CSPIInstance类
  6. I2CSPIDriverBase类
  7. I2CSPIDriver类
  8. I2C/SPI总线选项

2. 基础类和定义

2.1 ListNode类

主要功能描述:

  1. 采用类模板扩展ListNode应用范围
  2. 通过 setSibling 设置成员变量_list_node_sibling
  3. 通过 getSibling 获取成员变量_list_node_sibling

注：这个类类似于C语言单向链表的一个节点结构声明。

class ListNode

template<class T>
class ListNode

public:

	void setSibling(T sibling)  _list_node_sibling = sibling; 
	const T getSibling() const  return _list_node_sibling; 

protected:

	T _list_node_siblingnullptr;

;

2.2 List类

主要功能描述：

  1. 基于ListNode类实现了单链表功能
  2. 支持新增一个ListNode操作: void add(T newNode)
  3. 支持删除一个ListNode操作: bool remove(T removeNode)/void deleteNode(T node)
  4. 支持列表是否为空判断: bool empty()
  5. 支持列表清空操作: void clear()
  6. 支持列表元素数量获取: size_t size()
  7. 支持列表头元素获取: const T getHead()
  8. 支持Iterator操作: Iterator begin()/Iterator end()

class List

template<class T>
class List

public:

	void add(T newNode)
	
		if (_head == nullptr) 
			// list is empty, add as head
			_head = newNode;
			return;

		 else 
			// find last node and add to end
			T node = _head;

			while (node != nullptr) 
				if (node->getSibling() == nullptr) 
					// found last node, now add newNode
					node->setSibling(newNode);
					return;
				

				node = node->getSibling();
			
		
	

	bool remove(T removeNode)
	
		if (removeNode == nullptr) 
			return false;
		

		// base case
		if (removeNode == _head) 
			if (_head != nullptr) 
				_head = _head->getSibling();
			

			removeNode->setSibling(nullptr);

			return true;
		

		for (T node = getHead(); node != nullptr; node = node->getSibling()) 
			// is sibling the node to remove?
			if (node->getSibling() == removeNode) 
				// replace sibling
				if (node->getSibling() != nullptr) 
					node->setSibling(node->getSibling()->getSibling());

				 else 
					node->setSibling(nullptr);
				

				removeNode->setSibling(nullptr);

				return true;
			
		

		return false;
	

	struct Iterator 
		T node;
		explicit Iterator(T v) : node(v) 

		operator T() const  return node; 
		operator T &()  return node; 
		const T &operator* () const  return node; 
		Iterator &operator++ ()
		
			if (node) 
				node = node->getSibling();
			

			return *this;
		
	;

	Iterator begin()  return Iterator(getHead()); 
	Iterator end()  return Iterator(nullptr); 

	const T getHead() const  return _head; 

	bool empty() const  return getHead() == nullptr; 

	size_t size() const
	
		size_t sz = 0;

		for (auto node = getHead(); node != nullptr; node = node->getSibling()) 
			sz++;
		

		return sz;
	

	void deleteNode(T node)
	
		if (remove(node)) 
			// only delete if node was successfully removed
			delete node;
		
	

	void clear()
	
		auto node = getHead();

		while (node != nullptr) 
			auto next = node->getSibling();
			delete node;
			node = next;
		

		_head = nullptr;
	

protected:

	T _headnullptr;
;

2.3 BusCLIArguments类

命令行参数配置总线设备。

主要功能描述：

  1. 支持总线参数命令行解析: parseDefaultArguments
  2. 支持总线参数检查: validateConfiguration
  3. 总线参数类型：I2C(_i2c_support) or SPI(_spi_support)
  4. 支持总线选项: I2C/SPI 内部/外部(bus_option)
  5. 内部总线号(requested_bus)
  6. 支持总线工作频率设置(bus_frequency)
  7. 支持静默启动功能(quiet_start) //do not print a message when startup fails
  8. 【代码中未见相关功能】支持总线PNP动态功能???(keep_running) //eep driver running even if no device is detected on startup
  9. 支持是否需要keep_running功能(support_keep_running) //true if keep_running (see above) is supported
  10. 支持硬件mount方向修正(rotation) //sensor rotation (MAV_SENSOR_ROTATION_* or distance_sensor_s::ROTATION_*)
  11. 支持设备相关自定义参数(custom1/custom2/custom_data) //driver-specific custom argument
  12. I2C 总线
    I2C Slave地址(i2c_address)
    I2C默认频率(default_i2c_frequency)
  13. SPI 总线
    SPI芯片选择(chipselect)
    SPI工作模式(spi_mode)
    SPI默认频率(default_spi_frequency)

class BusCLIArguments

class BusCLIArguments

public:
	BusCLIArguments(bool i2c_support, bool spi_support)
#if defined(CONFIG_I2C) || defined(CONFIG_SPI)
		:
#endif // CONFIG_I2C || CONFIG_SPI
#if defined(CONFIG_I2C)
		_i2c_support(i2c_support)
#endif // CONFIG_I2C
#if defined(CONFIG_I2C) && defined(CONFIG_SPI)
		,
#endif // CONFIG_I2C && CONFIG_SPI
#if defined(CONFIG_SPI)
		_spi_support(spi_support)
#endif // CONFIG_SPI
	

	/**
	 * Parse CLI arguments (for drivers that don't need any custom arguments, otherwise getopt() should be used)
	 * @return command (e.g. "start") or nullptr on error or unknown argument
	 */
	const char *parseDefaultArguments(int argc, char *argv[]);

	/**
	 * Like px4_getopt(), but adds and handles i2c/spi driver-specific arguments
	 */
	int getOpt(int argc, char *argv[], const char *options);

	/**
	 * returns the current optional argument (for options like 'T:'), or the command (e.g. "start")
	 * @return nullptr or argument/command
	 */
	const char *optArg() const  return _optarg; 


	I2CSPIBusOption bus_optionI2CSPIBusOption::All;
	int requested_bus-1;
	int bus_frequency0;
#if defined(CONFIG_SPI)
	int chipselect -1;
	spi_mode_e spi_modeSPIDEV_MODE3;
#endif // CONFIG_SPI
#if defined(CONFIG_I2C)
	uint8_t i2c_address 0; ///< I2C address (a driver must set the default address)
#endif // CONFIG_I2C
	bool quiet_start false; ///< do not print a message when startup fails
	bool keep_runningfalse; ///< keep driver running even if no device is detected on startup

	Rotation rotationROTATION_NONE; ///< sensor rotation (MAV_SENSOR_ROTATION_* or distance_sensor_s::ROTATION_*)

	int custom10; ///< driver-specific custom argument
	int custom20; ///< driver-specific custom argument
	void *custom_datanullptr; ///< driver-specific custom argument

	// driver defaults, if not specified via CLI
#if defined(CONFIG_SPI)
	int default_spi_frequency -1; ///< default spi bus frequency (driver needs to set this) [Hz]
#endif // CONFIG_SPI
#if defined(CONFIG_I2C)
	int default_i2c_frequency -1; ///< default i2c bus frequency (driver needs to set this) [Hz]
#endif // CONFIG_I2C

	bool support_keep_runningfalse; ///< true if keep_running (see above) is supported

private:
	bool validateConfiguration();

	char _options[32] ;
	int _optind1;
	const char *_optargnullptr;
#if defined(CONFIG_I2C)
	const bool _i2c_support;
#endif // CONFIG_I2C
#if defined(CONFIG_SPI)
	const bool _spi_support;
#endif // CONFIG_SPI
;

2.4 BusInstanceIterator类

使用给定的过滤器选项迭代运行实例和/或配置的I2C/SPI总线。

主要功能描述：

  1. 支持I2C/SPI总线配置
  2. 支持I2C/SPI总线设备添加
  3. 支持I2C/SPI总线设备移除
  4. 支持I2C/SPI总线设备相关属性的获取

class BusInstanceIterator

class BusInstanceIterator

public:
	BusInstanceIterator(const char *module_name, const BusCLIArguments &cli_arguments, uint16_t devid_driver_index);
	~BusInstanceIterator();

	I2CSPIBusOption configuredBusOption() const  return _bus_option; 

	int runningInstancesCount() const;

	bool next();

	I2CSPIInstance *instance() const;
	void removeInstance();
	board_bus_types busType() const;
	int bus() const;
	uint32_t devid() const;

#if defined(CONFIG_SPI)
	spi_drdy_gpio_t DRDYGPIO() const;
#endif // CONFIG_SPI

	bool external() const;
	int externalBusIndex() const;
	int busDeviceIndex() const;

	void addInstance(I2CSPIInstance *instance);

#if defined(CONFIG_I2C)
	static I2CBusIterator::FilterType i2cFilter(I2CSPIBusOption bus_option);
#endif // CONFIG_I2C
#if defined(CONFIG_SPI)
	static SPIBusIterator::FilterType spiFilter(I2CSPIBusOption bus_option);
#endif // CONFIG_SPI

	const char *moduleName() const  return _module_name; 
	uint16_t devidDriverIndex() const  return _devid_driver_index; 

private:
	const char *_module_name;
	const I2CSPIBusOption _bus_option;
	const uint16_t _devid_driver_index;
#if defined(CONFIG_I2C)
	const uint8_t _i2c_address;
#endif // CONFIG_I2C
#if defined(CONFIG_SPI)
	SPIBusIterator _spi_bus_iterator;
#endif // CONFIG_SPI
#if defined(CONFIG_I2C)
	I2CBusIterator _i2c_bus_iterator;
#endif // CONFIG_I2C
	List<I2CSPIInstance *>::Iterator _current_instance;
;

2.5 I2CSPIInstance类

I2CSPI实例类对象定义。

主要功能描述：

  1. 支持I2C/SPI总线实例对象类声明
  2. 支持I2C/SPI总线类对象BusInstanceIterator/I2CSPIDriverBase友元类

class I2CSPIInstance

class I2CSPIInstance : public ListNode<I2CSPIInstance *>

public:
	virtual ~I2CSPIInstance() = default;
#if defined(CONFIG_I2C)
	virtual int8_t  get_i2c_address() return _i2c_address;
#endif // CONFIG_I2C
private:
	I2CSPIInstance(const I2CSPIDriverConfig &config)
		: _module_name(config.module_name), _bus_option(config.bus_option), _bus(config.bus),
		  _devid_driver_index(config.devid_driver_index), _bus_device_index(config.bus_device_index)
#if defined(CONFIG_I2C)
		, _i2c_address(config.i2c_address)
#endif // CONFIG_I2C
	


	friend class BusInstanceIterator;
	friend class I2CSPIDriverBase;

	const char *_module_name;
	const I2CSPIBusOption _bus_option;
	const int _bus;
	const uint16_t _devid_driver_index;
	const int8_t _bus_device_index;
#if defined(CONFIG_I2C)
	const int8_t _i2c_address; ///< I2C address (optional)
#endif // CONFIG_I2C
;

2.6 I2CSPIDriverBase类

I2CSPI驱动基础功能类对象定义。

主要功能描述：

  1. 支持I2C/SPI驱动基础功能模块启动
  2. 支持I2C/SPI驱动基础功能模块停止
  3. 支持I2C/SPI驱动基础功能模块状态查询

class I2CSPIDriverBase

class I2CSPIDriverBase : public px4::ScheduledWorkItem, public I2CSPIInstance

public:
	I2CSPIDriverBase(const I2CSPIDriverConfig &config)
		: ScheduledWorkItem(config.module_name, config.wq_config),
		  I2CSPIInstance(config) 

	static int module_stop(BusInstanceIterator &iterator);
	static int module_status(BusInstanceIterator &iterator);
	static int module_custom_method(const BusCLIArguments &cli, BusInstanceIterator &iterator,
					bool run_on_work_queue = true);

	using instantiate_method = I2CSPIDriverBase * (*)(const I2CSPIDriverConfig &config, int runtime_instance);
protected:
	virtual ~I2CSPIDriverBase() = default;

	virtual void print_status();

	virtual void custom_method(const BusCLIArguments &cli) 

	/**
	 * Exiting the module. A driver can override this, for example to unregister interrupt callbacks.
	 * This will be called from the work queue.
	 * A module overriding this, needs to call I2CSPIDriverBase::exit_and_cleanup() as the very last statement.
	 */
	virtual void exit_and_cleanup()  ScheduleClear(); _task_exited.store(true); 

	bool should_exit() const  return _task_should_exit.load(); 

	static int module_start(const BusCLIArguments &cli, BusInstanceIterator &iterator, void(*print_usage)(),
				instantiate_method instantiate);

private:
	static void custom_method_trampoline(void *argument);

	void request_stop_and_wait();

	px4::atomic_bool _task_should_exitfalse;
	px4::atomic_bool _task_exitedfalse;
;

2.7 I2CSPIDriver类

I2CSPI驱动类对象定义。

主要功能描述：

  1. 支持驱动定制启动
  2. 支持驱动定义业务运行逻辑

class I2CSPIDriver

template<class T>
class I2CSPIDriver : public I2CSPIDriverBase

public:
	static int module_start(const BusCLIArguments &cli, BusInstanceIterator &iterator)
	
		return I2CSPIDriverBase::module_start(cli, iterator, &T::print_usage, InstantiateHelper<T>::m);
	

protected:
	I2CSPIDriver(const I2CSPIDriverConfig &config)
		: I2CSPIDriverBase(config) 

	virtual ~I2CSPIDriver() = default;

	// *INDENT-OFF* remove once there's astyle >3.1 in CI
	void Run() final
	
		static_cast<T *>(this)->RunImpl();

		if (should_exit()) 
			exit_and_cleanup();
		
	
	// *INDENT-ON*
private:

	// SFINAE to use R::instantiate if it exists, and R::instantiate_default otherwise
	template <typename R>
	class InstantiateHelper
	
		template <typename C>
		static constexpr I2CSPIDriverBase::instantiate_method get(decltype(&C::instantiate))  return &C::instantiate; 
		template <typename C>
		static constexpr I2CSPIDriverBase::instantiate_method get(...)  return &C::instantiate_default; 
	public:
		static constexpr I2CSPIDriverBase::instantiate_method m = get<R>(0);
	;

	static I2CSPIDriverBase *instantiate_default(const I2CSPIDriverConfig &config, int runtime_instance)
	
		T *instance = new T(config);

		if (!instance) 
			PX4_ERR("alloc failed");
			return nullptr;
		

		if (OK != instance->init()) 
			delete instance;
			return nullptr;
		

		return instance;
	
;

2.8 I2C/SPI总线选项

PX4系统的I2C/SPI总线分为I2C内部和外部，以及SPI内部和外部四大类。

enum class I2CSPIBusOption : uint8_t 
	All = 0, ///< select all runnning instances
#if defined(CONFIG_I2C)
	I2CInternal,
	I2CExternal,
#endif // CONFIG_I2C
#if defined(CONFIG_SPI)
	SPIInternal,
	SPIExternal,
#endif // CONFIG_SPI
;

3. 总结

注：暂时先整理这些内容，后续随着代码阅读的增加，再补充完善。

4. 参考资料

【1】PX4开源软件框架简明简介
【2】PX4模块设计之十二：High Resolution Timer设计
【3】PX4模块设计之十三：WorkQueue设计

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