202 lines
7.2 KiB
C
202 lines
7.2 KiB
C
/* The industrial I/O core - generic buffer interfaces.
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*
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* Copyright (c) 2008 Jonathan Cameron
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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#ifndef _IIO_BUFFER_GENERIC_H_
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#define _IIO_BUFFER_GENERIC_H_
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#include <linux/sysfs.h>
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#include <linux/iio/iio.h>
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#include <linux/kref.h>
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#ifdef CONFIG_IIO_BUFFER
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struct iio_buffer;
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/**
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* INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be
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* configured. It has a fixed value which will be buffer specific.
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*/
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#define INDIO_BUFFER_FLAG_FIXED_WATERMARK BIT(0)
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/**
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* struct iio_buffer_access_funcs - access functions for buffers.
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* @store_to: actually store stuff to the buffer
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* @read_first_n: try to get a specified number of bytes (must exist)
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* @data_available: indicates how much data is available for reading from
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* the buffer.
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* @request_update: if a parameter change has been marked, update underlying
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* storage.
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* @set_bytes_per_datum:set number of bytes per datum
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* @set_length: set number of datums in buffer
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* @enable: called if the buffer is attached to a device and the
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* device starts sampling. Calls are balanced with
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* @disable.
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* @disable: called if the buffer is attached to a device and the
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* device stops sampling. Calles are balanced with @enable.
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* @release: called when the last reference to the buffer is dropped,
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* should free all resources allocated by the buffer.
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* @modes: Supported operating modes by this buffer type
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* @flags: A bitmask combination of INDIO_BUFFER_FLAG_*
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*
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* The purpose of this structure is to make the buffer element
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* modular as event for a given driver, different usecases may require
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* different buffer designs (space efficiency vs speed for example).
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*
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* It is worth noting that a given buffer implementation may only support a
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* small proportion of these functions. The core code 'should' cope fine with
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* any of them not existing.
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**/
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struct iio_buffer_access_funcs {
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int (*store_to)(struct iio_buffer *buffer, const void *data);
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int (*read_first_n)(struct iio_buffer *buffer,
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size_t n,
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char __user *buf);
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size_t (*data_available)(struct iio_buffer *buffer);
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int (*request_update)(struct iio_buffer *buffer);
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int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
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int (*set_length)(struct iio_buffer *buffer, int length);
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int (*enable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
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int (*disable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
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void (*release)(struct iio_buffer *buffer);
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unsigned int modes;
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unsigned int flags;
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};
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/**
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* struct iio_buffer - general buffer structure
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* @length: [DEVICE] number of datums in buffer
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* @bytes_per_datum: [DEVICE] size of individual datum including timestamp
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* @scan_el_attrs: [DRIVER] control of scan elements if that scan mode
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* control method is used
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* @scan_mask: [INTERN] bitmask used in masking scan mode elements
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* @scan_timestamp: [INTERN] does the scan mode include a timestamp
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* @access: [DRIVER] buffer access functions associated with the
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* implementation.
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* @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
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* @buffer_group: [INTERN] attributes of the buffer group
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* @scan_el_group: [DRIVER] attribute group for those attributes not
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* created from the iio_chan_info array.
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* @pollq: [INTERN] wait queue to allow for polling on the buffer.
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* @stufftoread: [INTERN] flag to indicate new data.
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* @attrs: [INTERN] standard attributes of the buffer
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* @demux_list: [INTERN] list of operations required to demux the scan.
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* @demux_bounce: [INTERN] buffer for doing gather from incoming scan.
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* @buffer_list: [INTERN] entry in the devices list of current buffers.
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* @ref: [INTERN] reference count of the buffer.
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* @watermark: [INTERN] number of datums to wait for poll/read.
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*/
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struct iio_buffer {
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int length;
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int bytes_per_datum;
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struct attribute_group *scan_el_attrs;
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long *scan_mask;
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bool scan_timestamp;
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const struct iio_buffer_access_funcs *access;
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struct list_head scan_el_dev_attr_list;
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struct attribute_group buffer_group;
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struct attribute_group scan_el_group;
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wait_queue_head_t pollq;
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bool stufftoread;
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const struct attribute **attrs;
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struct list_head demux_list;
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void *demux_bounce;
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struct list_head buffer_list;
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struct kref ref;
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unsigned int watermark;
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};
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/**
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* iio_update_buffers() - add or remove buffer from active list
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* @indio_dev: device to add buffer to
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* @insert_buffer: buffer to insert
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* @remove_buffer: buffer_to_remove
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*
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* Note this will tear down the all buffering and build it up again
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*/
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int iio_update_buffers(struct iio_dev *indio_dev,
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struct iio_buffer *insert_buffer,
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struct iio_buffer *remove_buffer);
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/**
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* iio_buffer_init() - Initialize the buffer structure
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* @buffer: buffer to be initialized
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**/
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void iio_buffer_init(struct iio_buffer *buffer);
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int iio_scan_mask_query(struct iio_dev *indio_dev,
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struct iio_buffer *buffer, int bit);
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/**
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* iio_push_to_buffers() - push to a registered buffer.
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* @indio_dev: iio_dev structure for device.
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* @data: Full scan.
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*/
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int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data);
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/*
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* iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers
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* @indio_dev: iio_dev structure for device.
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* @data: sample data
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* @timestamp: timestamp for the sample data
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*
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* Pushes data to the IIO device's buffers. If timestamps are enabled for the
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* device the function will store the supplied timestamp as the last element in
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* the sample data buffer before pushing it to the device buffers. The sample
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* data buffer needs to be large enough to hold the additional timestamp
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* (usually the buffer should be indio->scan_bytes bytes large).
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*
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* Returns 0 on success, a negative error code otherwise.
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*/
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static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev,
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void *data, int64_t timestamp)
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{
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if (indio_dev->scan_timestamp) {
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size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1;
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((int64_t *)data)[ts_offset] = timestamp;
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}
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return iio_push_to_buffers(indio_dev, data);
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}
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int iio_update_demux(struct iio_dev *indio_dev);
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bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
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const unsigned long *mask);
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struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
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void iio_buffer_put(struct iio_buffer *buffer);
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/**
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* iio_device_attach_buffer - Attach a buffer to a IIO device
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* @indio_dev: The device the buffer should be attached to
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* @buffer: The buffer to attach to the device
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*
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* This function attaches a buffer to a IIO device. The buffer stays attached to
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* the device until the device is freed. The function should only be called at
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* most once per device.
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*/
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static inline void iio_device_attach_buffer(struct iio_dev *indio_dev,
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struct iio_buffer *buffer)
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{
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indio_dev->buffer = iio_buffer_get(buffer);
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}
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#else /* CONFIG_IIO_BUFFER */
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static inline void iio_buffer_get(struct iio_buffer *buffer) {}
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static inline void iio_buffer_put(struct iio_buffer *buffer) {}
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#endif /* CONFIG_IIO_BUFFER */
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#endif /* _IIO_BUFFER_GENERIC_H_ */
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