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