linux驱动由浅入深系列：高通sensor架构实例分析之二(驱动代码结构)

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上一篇文章中我们了解了高通sensor的整体架构及对AP侧的代码进行了分析，这篇文章我们详细分析一下aDSP侧的代码结构。

sensor数据流关键代码概览

下图是sensor数据流程中的关键代码部分:

实现sensor驱动最重要的一个结构体

结合上一篇的测试代码，可以清楚的看到高通sensor的数据处理流程。图中7位置指示了每个基于ADSP架构的传感器需要实现的接口如下：

typedef struct
{
/**
* @brief Initializes the driver and sets up devices.
*
* Allocates a handle to a driver instance, opens a communication port to
* associated devices, configures the driver and devices, and places
* the devices in the default power state. Returns the instance handle along
* with a list of supported sensors. This function will be called at init
* time.
*
* @param[out] dd_handle_ptr Pointer that this function must malloc and
* populate. This is a handle to the driver
* instance that will be passed in to all other
* functions. NB: Do not use @a memhandler to
* allocate this memory.
* @param[in] smgr_handle Handle used to identify this driver when it
* calls into Sensors Manager functions.
* @param[in] nv_params NV parameters retrieved for the driver.
* @param[in] device_info Access info for physical devices controlled by
* this driver. Used to configure the bus
* and talk to the devices.
* @param[in] num_devices Number of elements in @a device_info.
* @param[in] memhandler Memory handler used to dynamically allocate
* output parameters, if applicable. NB: Do not
* use memhandler to allocate memory for
* @a dd_handle_ptr.
* @param[in/out] sensors List of supported sensors, allocated,
* populated, and returned by this function.
* @param[in/out] num_sensors Number of elements in @a sensors.
*
* @return Success if @a dd_handle_ptr was allocated and the driver was
* configured properly. Otherwise a specific error code is returned.
*/
sns_ddf_status_e (*init)(
sns_ddf_handle_t* dd_handle_ptr,
sns_ddf_handle_t smgr_handle,
sns_ddf_nv_params_s* nv_params,
sns_ddf_device_access_s device_info[],
uint32_t num_devices,
sns_ddf_memhandler_s* memhandler,
sns_ddf_sensor_e** sensors,
uint32_t* num_sensors);
/**
* @brief Retrieves a single set of sensor data.
*
* Requests a single sample of sensor data from each of the specified
* sensors. Data is returned in one of two ways: (1) immediately after being
* read from the sensor, in which case data is populated in the same order
* it was requested, or (2) in cases where the sensor requires several steps
* to be read, this function will return with the status SNS_DDF_PENDING,
* and provide the data asynchronously via @a sns_ddf_smgr_data_notify()
* when it is ready. Note that @a sns_ddf_smgr_data_notify() must be called
* even in the event of an error in order to report a failed status. An
* asynchronous notification is also expected in the case of mixed data
* (i.e. synchronous and asynchronous).
*
* @note In the case where multiple sensors are requested, the driver must
* attempt to collect data from all requested sensors, meaning that
* the time it takes to execute this function will be determined by
* the number of sensors sampled, and their various delays. Drivers
* must never return partial responses. If a sensor has failed or
* isn't available, @a sns_ddf_sensor_data_s.status must be used to
* reflect this status.
*
* @param[in] dd_handle Handle to a driver instance.
* @param[in] sensors List of sensors for which data is requested.
* @param[in] num_sensors Number of elements in @a sensors.
* @param[in] memhandler Memory handler used to dynamically allocate
* output parameters, if applicable.
* @param[out] data Sampled sensor data. The number of elements must
* match @a num_sensors.
*
* @return SNS_DDF_SUCCESS if data was populated successfully. If any of the
* sensors queried are to be read asynchronously SNS_DDF_PENDING is
* returned and data is via @a sns_ddf_smgr_data_notify() when
* available. Otherwise a specific error code is returned.
*
* @see sns_ddf_data_notify()
*/
sns_ddf_status_e (*get_data)(
sns_ddf_handle_t dd_handle,
sns_ddf_sensor_e sensors[],
uint32_t num_sensors,
sns_ddf_memhandler_s* memhandler,
sns_ddf_sensor_data_s** data);
/**
* @brief Sets a sensor attribute to a specific value.
*
* @param[in] dd_handle Handle to a driver instance.
* @param[in] sensor Sensor for which this attribute is to be set. When
* addressing an attribute that refers to the driver
* this value is set to SNS_DDF_SENSOR__ALL.
* @param[in] attrib Attribute to be set.
* @param[in] value Value to set this attribute.
*
* @return Success if the value of the attribute was set properly. Otherwise
* a specific error code is returned.
*/
sns_ddf_status_e (*set_attrib)(
sns_ddf_handle_t dd_handle,
sns_ddf_sensor_e sensor,
sns_ddf_attribute_e attrib,
void* value);
/**
* @brief Retrieves the value of an attribute for a sensor.
*
* @param[in] dd_handle Handle to a driver instance.
* @param[in] sensor Sensor whose attribute is to be retrieved. When
* addressing an attribute that refers to the driver
* this value is set to SNS_DDF_SENSOR__ALL.
* @param[in] attrib Attribute to be retrieved.
* @param[in] memhandler Memory handler used to dynamically allocate
* output parameters, if applicable.
* @param[out] value Pointer that this function will allocate or set
* to the attribute's value.
* @param[out] num_elems Number of elements in @a value.
*
* @return Success if the attribute was retrieved and the buffer was
* populated. Otherwise a specific error code is returned.
*/
sns_ddf_status_e (*get_attrib)(
sns_ddf_handle_t dd_handle,
sns_ddf_sensor_e sensor,
sns_ddf_attribute_e attrib,
sns_ddf_memhandler_s* memhandler,
void** value,
uint32_t* num_elems);
/**
* @brief Called when the timer set by this driver has expired. This must be
* the callback function submitted when initializing a timer.
*
* @note This will be called within the context of the Sensors Manager task.
*
* @param[in] dd_handle Handle to a driver instance.
* @param[in] arg The argument submitted when the timer was set.
*
* @see sns_ddf_set_timer()
*/
void (*handle_timer)(sns_ddf_handle_t dd_handle, void* arg);
/**
* @brief Called in response to an interrupt for this driver.
*
* @note This function will be called within the context of the SMGR task,
* *not* the ISR.
*
* @param[in] dd_handle Handle to a driver instance.
* @param[in] gpio_num GPIO number that triggered this interrupt.
* @param[in] timestamp Time at which interrupt happened.
*/
void (*handle_irq)(
sns_ddf_handle_t dd_handle,
uint32_t gpio_num,
sns_ddf_time_t timestamp);
/**
* @brief Resets the driver and device so they return to the state they were
* in after init() was called.
*
* @param[in] dd_handle Handle to a driver instance.
*
* @return Success if the driver was able to reset its state and the device.
* Otherwise a specific error code is returned.
*/
sns_ddf_status_e (*reset)(sns_ddf_handle_t dd_handle);
/**
* @brief Runs a factory test case.
*
* Tests may include embedded hardware tests in cases where the sensor
* supports it, as well as driver based sensor tests. This is generally run
* in a factory setting and must not be called while a device is streaming
* data.
*
* @param[in] dd_handle Handle to a driver instance.
* @param[in] sensor Sensor on which to run the test.
* @param[in] test Test case to run.
* @param[out] err Optional driver-specific error code.
*
* @return One of the following error codes:
* SNS_DDF_SUCCESS - Test passed.
* SNS_DDF_PENDING - Test result will be sent as an event.
* SNS_DDF_EDEVICE_BUSY - Device is busy streaming, cannot run test.
* SNS_DDF_EINVALID_TEST - Test is not defined for this sensor.
* SNS_DDF_EINVALID_PARAM - One of the parameters is invalid.
* SNS_DDF_EFAIL - Unknown error occurred.
*/
sns_ddf_status_e (*run_test)(
sns_ddf_handle_t dd_handle,
sns_ddf_sensor_e sensor,
sns_ddf_test_e test,
uint32_t* err);
/**
* @brief Begins device-scheduled sampling and enables notification via Data
* Ready Interrupts (DRI).
*
* The driver commands the device to begin sampling at the configured
* ODR (@a SNS_DDF_ATTRIB_ODR) and enables DRI. When data is ready, the
* driver's handle_irq() function is called and the driver notifies
* SMGR of the event via @a sns_ddf_smgr_notify_event() and @a
* SNS_DDF_EVENT_DATAREADY.
*
* @param[in] handle Handle to the driver's instance.
* @param[in] sensor Sensor to be sampled.
* @param[in] enable True to enable or false to disable data stream.
*
* @return SNS_DDF_SUCCESS if sensor was successfully configured and
* internal sampling has commenced or ceased. Otherwise an
* appropriate error code.
*/
sns_ddf_status_e (*enable_sched_data)(
sns_ddf_handle_t handle,
sns_ddf_sensor_e sensor,
bool enable);
/**
* @brief Probes for the device with a given configuration.
*
* This commands the driver to look for the device with the specified
* configuration (ie, I2C address/bus defined in the sns_ddf_device_access_s
* struct.
*
* @param[in] dev_info Access info for physical devices controlled by
* this driver. Used to determine if the device is
* physically present.
* @param[in] memhandler Memory handler used to dynamically allocate
* output parameters, if applicable.
* @param[out] num_sensors Number of sensors supported. 0 if none.
* @param[out] sensor_type Array of sensor types supported, with num_sensor
* elements. Allocated by this function.
*
* @return SNS_DDF_SUCCESS if the part was probed function completed, even
* if no device was found (in which case num_sensors will be set to
* 0).
*/
sns_ddf_status_e(*probe)(
sns_ddf_device_access_s* device_info,
sns_ddf_memhandler_s* memhandler,
uint32_t* num_sensors,
sns_ddf_sensor_e** sensors );
/**
* @brief Retrieves a set of sensor data. Asynchronous API
*
* Requests sample of sensor data from the specified sensor.
*
* @note If a sensor has failed or
* isn't available, @a sns_ddf_sensor_data_s.status must be used to
* reflect this status.
*
* @param[in] dd_handle Handle to a driver instance.
* @param[in] sensor sensor for which data is requested.
*
* @param[in] num_samples number of samples to retrieve as available. Drain the FIFO if value is set to Zero.
* @param[in] trigger now trigger notify fifo data now or
* later when trigger_now is set to true.
*
*
* @return SNS_DDF_SUCCESS if data was populated successfully.
* via sns_ddf_smgr_data_notify() or if trigger_now is
* set to false; Otherwise a specific error code is
* returned.
*
* @see sns_ddf_data_notify_data() as this will be used to report the data.
*/
sns_ddf_status_e (*trigger_fifo_data)(
sns_ddf_handle_t dd_handle,
sns_ddf_sensor_e sensor,
uint16_t num_samples,
bool trigger_now);
/**
* @brief Delivers a Driver Access Framework message to the driver.
* Asynchronous/Synchronous API.
*
* @detail
*
* @param[in] dd_handle Handle to a driver instance.
* @param[in] req_id Request identifier.
* @param[in] req_msg Request message in the opaque payload. If no
* payload is supplied, then this pointer will be
* null.
* @param[in] req_size Number of bytes in @req_msg. If req_msg is empty,
* this value must be 0.
* @param[in] memhandler Memory handler used to dynamically allocate
* output parameters, if applicable.
* @param[out] resp_msg Pointer to the output message pointer. The output
* message must be allocated first using @memhandler.
* @param[out] resp_size Pointer to number of bytes in @resp_msg. If there
* is no DAF response message for the request, then
* this must be 0 to show that the DAF response is
* not present. Response messages are limited in
* size to @SNS_SMGR_MAX_DAF_MESSAGE_SIZE_V01 bytes.
* Any response message larger than
* @SNS_SMGR_MAX_DAF_MESSAGE_SIZE_V01 bytes will be
* truncated.
* @param[in] trans_id_ptr Pointer to the optional transaction identifier.
This will be null if a transaction ID was not
provided.
* @param[in] conn_handle The connection handle for the request message.
* This value must be saved if the particular request
* is expected to generate indications. Upon
* notifying the SMGR of an indication, this value
* must be provided to the SMGR.
*
* @return Success if the message was retrieved and the buffer was correctly
* populated. Otherwise a specific error code is returned.
*/
sns_ddf_status_e (*process_daf_req)(
sns_ddf_handle_t dd_handle,
uint32_t req_id,
const void* req_msg,
uint32_t req_size,
sns_ddf_memhandler_s* memhandler,
void** resp_msg,
uint32_t* resp_size,
const uint8_t* trans_id_ptr,
void* conn_handle);
/**
* @brief Cancels all of the driver's current Driver Access Framework
* asynchronous transactions for the provided connection handle.
*
* @note This does not have to cancel a response message in the process of
* being created.
* This function does not have to be implemented for drivers that do
* not support or implement any asynchronous messages (these messages
* require the usage of sns_ddf_smgr_notify_daf_ind).
*
* @param[in] dd_handle Handle to a driver instance.
* @param[in] conn_handle The connection handle for the client that is
* cancelling the Driver Access Framework
* transaction.
*/
void (*cancel_daf_trans)(
sns_ddf_handle_t dd_handle,
void* conn_handle);
} sns_ddf_driver_if_s;

aDSP初始化流程

aDSP的初始化工作从[Sns_init_dsps.c]文件中的 sns_init()函数开始，其中调用 -> sns_init_once(); -> SNS_INIT_FUNCTIONS存在一个各个模块的初始化函数指针列表，依次调用各个模块的初始化函数init_ptrs[i]() -> 其中我们关注传感器相关的[sns_smgr_main_uimg.c]sns_smgr_init() -> 创建了 [sns_smgr_main.c]sns_smgr_task() 进程 ->sns_smgr_hw_init(); ->sns_smgr_process_msg(); ->sns_smgr_process_reg_resp_msg(); ->sns_smgr_process_reg_data() ->sns_smgr_process_reg_devinfo() ->sns_smgr_parse_reg_devinfo_resp() -> 通过drv_fn_ptr->probe()指针，调用相应传感器实现的probe函数。如果某传感器没有实现probe函数，则调用sns_smgr_populate_cfg_from_devinfo()。

aDSP上报传感器数据

Sensor上报数据的三种方式：

1， （Polling）0x00调用一次get_data后启动timer，等到timer到时间后调用sns_ddf_driver_if_s中指定的handle_timer()函数上报一组传感器数据

2， （DRI）0x80调用enable_sched_data()启用DRI（Data ReadyInterrupt，数据完成中断），按照set_cycle_time指定的ODR（Output Data Rate，数据输出速率）进行数据采集，采集完成后调用sns_ddf_driver_if_s中指定的handle_irq()函数上报传感器数据。

3， （FIFO）0xD0调用trigger_fifo_data()函数启动FIFO模式，当数据量到达指定的阈值，触发sns_ddf_smgr_data_notify()函数上报一批数据。