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 * INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be
22 * configured. It has a fixed value which will be buffer specific.
24 #define INDIO_BUFFER_FLAG_FIXED_WATERMARK BIT(0)
27 * struct iio_buffer_access_funcs - access functions for buffers.
28 * @store_to: actually store stuff to the buffer
29 * @read_first_n: try to get a specified number of bytes (must exist)
30 * @data_available: indicates how much data is available for reading from
32 * @request_update: if a parameter change has been marked, update underlying
34 * @set_bytes_per_datum:set number of bytes per datum
35 * @set_length: set number of datums in buffer
36 * @enable: called if the buffer is attached to a device and the
37 * device starts sampling. Calls are balanced with
39 * @disable: called if the buffer is attached to a device and the
40 * device stops sampling. Calles are balanced with @enable.
41 * @release: called when the last reference to the buffer is dropped,
42 * should free all resources allocated by the buffer.
43 * @modes: Supported operating modes by this buffer type
44 * @flags: A bitmask combination of INDIO_BUFFER_FLAG_*
46 * The purpose of this structure is to make the buffer element
47 * modular as event for a given driver, different usecases may require
48 * different buffer designs (space efficiency vs speed for example).
50 * It is worth noting that a given buffer implementation may only support a
51 * small proportion of these functions. The core code 'should' cope fine with
52 * any of them not existing.
54 struct iio_buffer_access_funcs {
55 int (*store_to)(struct iio_buffer *buffer, const void *data);
56 int (*read_first_n)(struct iio_buffer *buffer,
59 size_t (*data_available)(struct iio_buffer *buffer);
61 int (*request_update)(struct iio_buffer *buffer);
63 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
64 int (*set_length)(struct iio_buffer *buffer, int length);
66 int (*enable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
67 int (*disable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
69 void (*release)(struct iio_buffer *buffer);
76 * struct iio_buffer - general buffer structure
77 * @length: [DEVICE] number of datums in buffer
78 * @bytes_per_datum: [DEVICE] size of individual datum including timestamp
79 * @scan_el_attrs: [DRIVER] control of scan elements if that scan mode
80 * control method is used
81 * @scan_mask: [INTERN] bitmask used in masking scan mode elements
82 * @scan_timestamp: [INTERN] does the scan mode include a timestamp
83 * @access: [DRIVER] buffer access functions associated with the
85 * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
86 * @scan_el_group: [DRIVER] attribute group for those attributes not
87 * created from the iio_chan_info array.
88 * @pollq: [INTERN] wait queue to allow for polling on the buffer.
89 * @stufftoread: [INTERN] flag to indicate new data.
90 * @demux_list: [INTERN] list of operations required to demux the scan.
91 * @demux_bounce: [INTERN] buffer for doing gather from incoming scan.
92 * @buffer_list: [INTERN] entry in the devices list of current buffers.
93 * @ref: [INTERN] reference count of the buffer.
94 * @watermark: [INTERN] number of datums to wait for poll/read.
99 struct attribute_group *scan_el_attrs;
102 const struct iio_buffer_access_funcs *access;
103 struct list_head scan_el_dev_attr_list;
104 struct attribute_group buffer_group;
105 struct attribute_group scan_el_group;
106 wait_queue_head_t pollq;
108 const struct attribute **attrs;
109 struct list_head demux_list;
111 struct list_head buffer_list;
113 unsigned int watermark;
117 * iio_update_buffers() - add or remove buffer from active list
118 * @indio_dev: device to add buffer to
119 * @insert_buffer: buffer to insert
120 * @remove_buffer: buffer_to_remove
122 * Note this will tear down the all buffering and build it up again
124 int iio_update_buffers(struct iio_dev *indio_dev,
125 struct iio_buffer *insert_buffer,
126 struct iio_buffer *remove_buffer);
129 * iio_buffer_init() - Initialize the buffer structure
130 * @buffer: buffer to be initialized
132 void iio_buffer_init(struct iio_buffer *buffer);
134 int iio_scan_mask_query(struct iio_dev *indio_dev,
135 struct iio_buffer *buffer, int bit);
138 * iio_push_to_buffers() - push to a registered buffer.
139 * @indio_dev: iio_dev structure for device.
142 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data);
145 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers
146 * @indio_dev: iio_dev structure for device.
148 * @timestamp: timestamp for the sample data
150 * Pushes data to the IIO device's buffers. If timestamps are enabled for the
151 * device the function will store the supplied timestamp as the last element in
152 * the sample data buffer before pushing it to the device buffers. The sample
153 * data buffer needs to be large enough to hold the additional timestamp
154 * (usually the buffer should be indio->scan_bytes bytes large).
156 * Returns 0 on success, a negative error code otherwise.
158 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev,
159 void *data, int64_t timestamp)
161 if (indio_dev->scan_timestamp) {
162 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1;
163 ((int64_t *)data)[ts_offset] = timestamp;
166 return iio_push_to_buffers(indio_dev, data);
169 int iio_update_demux(struct iio_dev *indio_dev);
171 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
172 const unsigned long *mask);
174 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
175 void iio_buffer_put(struct iio_buffer *buffer);
178 * iio_device_attach_buffer - Attach a buffer to a IIO device
179 * @indio_dev: The device the buffer should be attached to
180 * @buffer: The buffer to attach to the device
182 * This function attaches a buffer to a IIO device. The buffer stays attached to
183 * the device until the device is freed. The function should only be called at
184 * most once per device.
186 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev,
187 struct iio_buffer *buffer)
189 indio_dev->buffer = iio_buffer_get(buffer);
192 #else /* CONFIG_IIO_BUFFER */
194 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
195 static inline void iio_buffer_put(struct iio_buffer *buffer) {}
197 #endif /* CONFIG_IIO_BUFFER */
199 #endif /* _IIO_BUFFER_GENERIC_H_ */