1 /* The industrial I/O core - generic buffer interfaces.
3 * Copyright (c) 2008 Jonathan Cameron
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 as published by
7 * the Free Software Foundation.
10 #ifndef _IIO_BUFFER_GENERIC_H_
11 #define _IIO_BUFFER_GENERIC_H_
12 #include <linux/sysfs.h>
13 #include <linux/iio/iio.h>
14 #include <linux/kref.h>
16 #ifdef CONFIG_IIO_BUFFER
21 * struct iio_buffer_access_funcs - access functions for buffers.
22 * @store_to: actually store stuff to the buffer
23 * @read_first_n: try to get a specified number of bytes (must exist)
24 * @data_available: indicates how much data is available for reading from
26 * @request_update: if a parameter change has been marked, update underlying
28 * @set_bytes_per_datum:set number of bytes per datum
29 * @set_length: set number of datums in buffer
30 * @release: called when the last reference to the buffer is dropped,
31 * should free all resources allocated by the buffer.
33 * The purpose of this structure is to make the buffer element
34 * modular as event for a given driver, different usecases may require
35 * different buffer designs (space efficiency vs speed for example).
37 * It is worth noting that a given buffer implementation may only support a
38 * small proportion of these functions. The core code 'should' cope fine with
39 * any of them not existing.
41 struct iio_buffer_access_funcs {
42 int (*store_to)(struct iio_buffer *buffer, const void *data);
43 int (*read_first_n)(struct iio_buffer *buffer,
46 size_t (*data_available)(struct iio_buffer *buffer);
48 int (*request_update)(struct iio_buffer *buffer);
50 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
51 int (*set_length)(struct iio_buffer *buffer, int length);
53 void (*release)(struct iio_buffer *buffer);
57 * struct iio_buffer - general buffer structure
58 * @length: [DEVICE] number of datums in buffer
59 * @bytes_per_datum: [DEVICE] size of individual datum including timestamp
60 * @scan_el_attrs: [DRIVER] control of scan elements if that scan mode
61 * control method is used
62 * @scan_mask: [INTERN] bitmask used in masking scan mode elements
63 * @scan_timestamp: [INTERN] does the scan mode include a timestamp
64 * @access: [DRIVER] buffer access functions associated with the
66 * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
67 * @scan_el_group: [DRIVER] attribute group for those attributes not
68 * created from the iio_chan_info array.
69 * @pollq: [INTERN] wait queue to allow for polling on the buffer.
70 * @stufftoread: [INTERN] flag to indicate new data.
71 * @demux_list: [INTERN] list of operations required to demux the scan.
72 * @demux_bounce: [INTERN] buffer for doing gather from incoming scan.
73 * @buffer_list: [INTERN] entry in the devices list of current buffers.
74 * @ref: [INTERN] reference count of the buffer.
75 * @watermark: [INTERN] number of datums to wait for poll/read.
80 struct attribute_group *scan_el_attrs;
83 const struct iio_buffer_access_funcs *access;
84 struct list_head scan_el_dev_attr_list;
85 struct attribute_group buffer_group;
86 struct attribute_group scan_el_group;
87 wait_queue_head_t pollq;
89 const struct attribute **attrs;
90 struct list_head demux_list;
92 struct list_head buffer_list;
94 unsigned int watermark;
98 * iio_update_buffers() - add or remove buffer from active list
99 * @indio_dev: device to add buffer to
100 * @insert_buffer: buffer to insert
101 * @remove_buffer: buffer_to_remove
103 * Note this will tear down the all buffering and build it up again
105 int iio_update_buffers(struct iio_dev *indio_dev,
106 struct iio_buffer *insert_buffer,
107 struct iio_buffer *remove_buffer);
110 * iio_buffer_init() - Initialize the buffer structure
111 * @buffer: buffer to be initialized
113 void iio_buffer_init(struct iio_buffer *buffer);
115 int iio_scan_mask_query(struct iio_dev *indio_dev,
116 struct iio_buffer *buffer, int bit);
119 * iio_push_to_buffers() - push to a registered buffer.
120 * @indio_dev: iio_dev structure for device.
123 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data);
126 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers
127 * @indio_dev: iio_dev structure for device.
129 * @timestamp: timestamp for the sample data
131 * Pushes data to the IIO device's buffers. If timestamps are enabled for the
132 * device the function will store the supplied timestamp as the last element in
133 * the sample data buffer before pushing it to the device buffers. The sample
134 * data buffer needs to be large enough to hold the additional timestamp
135 * (usually the buffer should be indio->scan_bytes bytes large).
137 * Returns 0 on success, a negative error code otherwise.
139 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev,
140 void *data, int64_t timestamp)
142 if (indio_dev->scan_timestamp) {
143 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1;
144 ((int64_t *)data)[ts_offset] = timestamp;
147 return iio_push_to_buffers(indio_dev, data);
150 int iio_update_demux(struct iio_dev *indio_dev);
152 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
153 const unsigned long *mask);
155 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
156 void iio_buffer_put(struct iio_buffer *buffer);
159 * iio_device_attach_buffer - Attach a buffer to a IIO device
160 * @indio_dev: The device the buffer should be attached to
161 * @buffer: The buffer to attach to the device
163 * This function attaches a buffer to a IIO device. The buffer stays attached to
164 * the device until the device is freed. The function should only be called at
165 * most once per device.
167 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev,
168 struct iio_buffer *buffer)
170 indio_dev->buffer = iio_buffer_get(buffer);
173 #else /* CONFIG_IIO_BUFFER */
175 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
176 static inline void iio_buffer_put(struct iio_buffer *buffer) {}
178 #endif /* CONFIG_IIO_BUFFER */
180 #endif /* _IIO_BUFFER_GENERIC_H_ */