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/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/sysfs.h>
#include <linux/kref.h>
#include <uapi/linux/iio/buffer.h>
#include <linux/iio/buffer.h>
struct iio_dev;
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: try to get a specified number of bytes (must exist)
* @data_available: indicates how much data is available for reading from
* the buffer.
* @remove_from: remove scan from buffer. Drivers should calls this to
* remove a scan from a buffer.
* @write: try to write a number of bytes
* @space_available: returns the amount of bytes available in a 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)(struct iio_buffer *buffer, size_t n, char __user *buf);
size_t (*data_available)(struct iio_buffer *buffer);
int (*remove_from)(struct iio_buffer *buffer, void *data);
int (*write)(struct iio_buffer *buffer, size_t n, const char __user *buf);
size_t (*space_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, unsigned 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
* Note that the internals of this structure should only be of interest to
* those writing new buffer implementations.
struct iio_buffer {
/** @length: Number of datums in buffer. */
unsigned int length;
/** @flags: File ops flags including busy flag. */
unsigned long flags;
/** @bytes_per_datum: Size of individual datum including timestamp. */
size_t bytes_per_datum;
/* @direction: Direction of the data stream (in/out). */
enum iio_buffer_direction direction;
* @access: Buffer access functions associated with the
* implementation.
const struct iio_buffer_access_funcs *access;
/** @scan_mask: Bitmask used in masking scan mode elements. */
long *scan_mask;
/** @demux_list: List of operations required to demux the scan. */
struct list_head demux_list;
/** @pollq: Wait queue to allow for polling on the buffer. */
wait_queue_head_t pollq;
/** @watermark: Number of datums to wait for poll/read. */
unsigned int watermark;
/* private: */
/* @scan_timestamp: Does the scan mode include a timestamp. */
bool scan_timestamp;
/* @buffer_attr_list: List of buffer attributes. */
struct list_head buffer_attr_list;
* @buffer_group: Attributes of the new buffer group.
* Includes scan elements attributes.
struct attribute_group buffer_group;
/* @attrs: Standard attributes of the buffer. */
const struct attribute **attrs;
/* @demux_bounce: Buffer for doing gather from incoming scan. */
void *demux_bounce;
/* @attached_entry: Entry in the devices list of buffers attached by the driver. */
struct list_head attached_entry;
/* @buffer_list: Entry in the devices list of current buffers. */
struct list_head buffer_list;
/* @ref: Reference count of the buffer. */
struct kref ref;
* 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);
struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
void iio_buffer_put(struct iio_buffer *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 */