179 lines
8.2 KiB
C
179 lines
8.2 KiB
C
/****************************************************************************
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* include/nuttx/sensors/cluster_driver.h
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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#ifndef __INCLUDE_NUTTX_SENSORS_CLUSTER_DRIVER_H
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#define __INCLUDE_NUTTX_SENSORS_CLUSTER_DRIVER_H
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/* Definitions for the cluster driver interface:
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*
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* The sensor cluster driver interface is created to permit high performance
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* collection and processing of sensor data. Normally when high performance
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* sensor data collection is required, data is needed from multiple sensors
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* and the collection/processing task needs to run as a "higher than user
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* priority" priority level. This mechanism is commonly supported by writing
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* the collection/processing task as a kernel driver worker thread that can
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* access multiple sensors.
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*
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* A clean way to implement this is to implement this collection/processing
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* mechanism is as a driver that has efficient kernel-to-kernel access to
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* other sensor leaf-drivers that support the cluster driver interface.
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* (This documentation describes the "cluster driver interface" from the
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* perspective of a "cluster driver interface" enabled leaf driver.)
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*
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* The file_operations interface typically deals with the caller's parameters
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* and buffers being in user space, while the driver's code, variables, and
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* buffers are in kernel space. There is also a layer of kernel code between
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* the caller and driver that deals with security and assists helps with the
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* driver's access of user space memory. So the file_operations interface
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* is not appropriate for driver-to-driver communication.
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*
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* Since the driver registration function is not part of the file_operations
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* interface and is permitted to be called from a kernel task, this function
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* is reused. But rather than being called by the board initialization
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* function, the cluster drivers registration function is called from the
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* board initialization function; and the cluster drivers registration
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* function calls the leaf driver's registration function.
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*
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* To be "cluster driver interface" enabled the leaf driver's registration
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* function must communicate the leaf driver's instance back to the cluster
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* driver's registration function. This is done by storing the leaf
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* driver's instance handle into the caller provided config structure.
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* This handle is provided as a parameter in cluster driver interface calls.
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*
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* dvr_open(): Reserve this sensor.
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*
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* dvr_close(): Places the sensor into low power standby mode, frees driver
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* resources associated with the sensor, and release the reservation
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* . of the sensor.
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*
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* To perform I/O to a sensor, the cluster driver needs...
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*
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* > A pointer to the spi instance (struct spi_dev_s *). The cluster driver
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* has this pointer, because it provides it to the leaf driver as an input
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* parameter to the leaf driver's registration function.
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* > The chip select gpio pin identifier for the sensor device. The cluster
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* driver knows this identifier,because it provides it to the leaf driver
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* as an input parameter to the leaf driver's registration function.
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* > A pointer to the leaf driver instance. The leaf driver communicates this
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* pointer to the cluster driver by storing it into the config struct
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* leaf_handle (struct spi_dev_s *) field that is also passed as an in/out
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* parameter in the leaf driver's registration function.
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*
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* With the above information, the sensor cluster driver may efficiently
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* access multiple sensors and aggregate their data.
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*
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****************************************************************************/
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/****************************************************************************
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* Public Types
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****************************************************************************/
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/* Cluster driver operations interface */
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struct sensor_cluster_operations_s
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{
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CODE int (*driver_open)(FAR void *instance_handle, int32_t arg);
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CODE int (*driver_close)(FAR void *instance_handle, int32_t arg);
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CODE ssize_t (*driver_read)(FAR void *instance_handle, FAR char *buffer,
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size_t buflen);
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CODE ssize_t (*driver_write)(FAR void *instance_handle,
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FAR const char *buffer, size_t buflen);
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CODE off_t (*driver_seek)(FAR void *instance_handle, off_t offset,
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int whence);
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CODE int (*driver_ioctl)(FAR void *instance_handle, int cmd,
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unsigned long arg);
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CODE int (*driver_suspend)(FAR void *instance_handle, int32_t arg);
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CODE int (*driver_resume)(FAR void *instance_handle, int32_t arg);
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};
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/****************************************************************************
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* Public Function Prototypes
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****************************************************************************/
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#ifdef __cplusplus
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#define EXTERN extern "C"
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extern "C"
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{
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#else
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#define EXTERN extern
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#endif
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/****************************************************************************
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* Name: xxxxxx_register <-- for a leaf driver.
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*
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* Description:
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* Example of a driver register function for a "sensor leaf driver" that
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* can be controlled by a "sensor cluster driver". The specific format of
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* the registration function will vary based on the characteristics of the
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* driver. The below is an example, which describes common aspects of the
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* function and and its parameters.
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*
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* Normally, sensor driver register functions are called by the board
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* initialization code. In the case of a "sensor cluster driver", the board
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* initialization code calls the register function of the "sensor cluster
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* driver"; and the "sensor cluster driver" calls the register function of
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* each of the sensor (leaf) drivers that it will be controlling.
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*
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* Input Parameters:
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* devpath - The full path to the leaf driver to register. E.g.,
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* "/dev/acl0"
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* spi - An instance of the SPI interface to use to communicate with
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* the leaf driver. Or, it could be the I2C driver instance if
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* the sensor is on an I2C bus.
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* config - configuration struct for the sensor leaf driver.
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* This struct is defined in the leaf driver's xxxxxx.h file.
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*
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* For a SPI sensor, this structure must contain:
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*
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* int spi_devid; The spi device id, which is used by NuttX to
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* select/deselect the device. This is usually some
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* type of reference to the chip_select gpio pin.
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* FAR void *leaf_handle; The handle to the leaf driver instance.
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* This is an opaque handle that provided by the
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* leaf driver's register function.
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* It is passed as a parameter to the leaf driver's
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* driver_open() and driver_close() functions.
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*
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* For an I2C sensor, this struct must contain:
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*
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* int i2c_devid; The i2c device id, which is used by NuttX to
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* address the sensor device on an I2C bus..
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* FAR void *leaf_handle; The handle to the leaf driver instance.
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* This is an opaque handle that provided by the
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* leaf driver's register function.
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* It is passed as a parameter to the leaf driver's
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* driver_open() and driver_close() functions.
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*
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* Returned Value:
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* Zero (OK) on success; a negated errno value on failure.
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*
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* int xxxxxx_register(FAR const char *devpath,
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* FAR struct spi_dev_s *spi,
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* FAR struct xxxxxx_config_s *config);
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*
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****************************************************************************/
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#undef EXTERN
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#ifdef __cplusplus
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}
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#endif
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#endif /* __INCLUDE_NUTTX_SENSORS_CLUSTER_DRIVER_H */
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