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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 "iio.h"
struct iio_buffer;
* 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)
* @request_update: if a parameter change has been marked, update underlying
* storage.
* @get_bytes_per_datum:get current bytes per datum
* @set_bytes_per_datum:set number of bytes per datum
* @get_length: get number of datums in buffer
* @set_length: set number of datums in buffer
* 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, u8 *data, s64 timestamp);
int (*read_first_n)(struct iio_buffer *buffer,
size_t n,
char __user *buf);
int (*request_update)(struct iio_buffer *buffer);
int (*get_bytes_per_datum)(struct iio_buffer *buffer);
int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
int (*get_length)(struct iio_buffer *buffer);
int (*set_length)(struct iio_buffer *buffer, int length);
* 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_index_timestamp:[INTERN] cache of the index to the timestamp
* @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.
* @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.
* @demux_list: [INTERN] list of operations required to demux the scan.
* @demux_bounce: [INTERN] buffer for doing gather from incoming scan.
struct iio_buffer {
int length;
int bytes_per_datum;
struct attribute_group *scan_el_attrs;
long *scan_mask;
bool scan_timestamp;
unsigned scan_index_timestamp;
const struct iio_buffer_access_funcs *access;
struct list_head scan_el_dev_attr_list;
struct attribute_group scan_el_group;
wait_queue_head_t pollq;
bool stufftoread;
const struct attribute_group *attrs;
struct list_head demux_list;
unsigned char *demux_bounce;
* iio_buffer_init() - Initialize the buffer structure
* @buffer: buffer to be initialized
void iio_buffer_init(struct iio_buffer *buffer);
void iio_buffer_deinit(struct iio_buffer *buffer);
* __iio_update_buffer() - update common elements of buffers
* @buffer: buffer that is the event source
* @bytes_per_datum: size of individual datum including timestamp
* @length: number of datums in buffer
static inline void __iio_update_buffer(struct iio_buffer *buffer,
int bytes_per_datum, int length)
buffer->bytes_per_datum = bytes_per_datum;
buffer->length = length;
int iio_scan_mask_query(struct iio_dev *indio_dev,
struct iio_buffer *buffer, int bit);
* iio_scan_mask_set() - set particular bit in the scan mask
* @buffer: the buffer whose scan mask we are interested in
* @bit: the bit to be set.
int iio_scan_mask_set(struct iio_dev *indio_dev,
struct iio_buffer *buffer, int bit);
* iio_push_to_buffer() - push to a registered buffer.
* @buffer: IIO buffer structure for device
* @scan: Full scan.
* @timestamp:
int iio_push_to_buffer(struct iio_buffer *buffer, unsigned char *data,
s64 timestamp);
int iio_update_demux(struct iio_dev *indio_dev);
* iio_buffer_register() - register the buffer with IIO core
* @indio_dev: device with the buffer to be registered
int iio_buffer_register(struct iio_dev *indio_dev,
const struct iio_chan_spec *channels,
int num_channels);
* iio_buffer_unregister() - unregister the buffer from IIO core
* @indio_dev: the device with the buffer to be unregistered
void iio_buffer_unregister(struct iio_dev *indio_dev);
* iio_buffer_read_length() - attr func to get number of datums in the buffer
ssize_t iio_buffer_read_length(struct device *dev,
struct device_attribute *attr,
char *buf);
* iio_buffer_write_length() - attr func to set number of datums in the buffer
ssize_t iio_buffer_write_length(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t len);
* iio_buffer_store_enable() - attr to turn the buffer on
ssize_t iio_buffer_store_enable(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t len);
* iio_buffer_show_enable() - attr to see if the buffer is on
ssize_t iio_buffer_show_enable(struct device *dev,
struct device_attribute *attr,
char *buf);
iio_buffer_read_length, \
iio_buffer_show_enable, \
int iio_sw_buffer_preenable(struct iio_dev *indio_dev);
static inline int iio_buffer_register(struct iio_dev *indio_dev,
struct iio_chan_spec *channels,
int num_channels)
return 0;
static inline void iio_buffer_unregister(struct iio_dev *indio_dev)
#endif /* CONFIG_IIO_BUFFER */
#endif /* _IIO_BUFFER_GENERIC_H_ */