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 whether data for reading from the buffer is
26 * @request_update: if a parameter change has been marked, update underlying
28 * @get_bytes_per_datum:get current bytes per datum
29 * @set_bytes_per_datum:set number of bytes per datum
30 * @get_length: get number of datums in buffer
31 * @set_length: set number of datums in buffer
32 * @release: called when the last reference to the buffer is dropped,
33 * should free all resources allocated by the buffer.
35 * The purpose of this structure is to make the buffer element
36 * modular as event for a given driver, different usecases may require
37 * different buffer designs (space efficiency vs speed for example).
39 * It is worth noting that a given buffer implementation may only support a
40 * small proportion of these functions. The core code 'should' cope fine with
41 * any of them not existing.
43 struct iio_buffer_access_funcs {
44 int (*store_to)(struct iio_buffer *buffer, const void *data);
45 int (*read_first_n)(struct iio_buffer *buffer,
48 bool (*data_available)(struct iio_buffer *buffer);
50 int (*request_update)(struct iio_buffer *buffer);
52 int (*get_bytes_per_datum)(struct iio_buffer *buffer);
53 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
54 int (*get_length)(struct iio_buffer *buffer);
55 int (*set_length)(struct iio_buffer *buffer, int length);
57 void (*release)(struct iio_buffer *buffer);
61 * struct iio_buffer - general buffer structure
62 * @length: [DEVICE] number of datums in buffer
63 * @bytes_per_datum: [DEVICE] size of individual datum including timestamp
64 * @scan_el_attrs: [DRIVER] control of scan elements if that scan mode
65 * control method is used
66 * @scan_mask: [INTERN] bitmask used in masking scan mode elements
67 * @scan_timestamp: [INTERN] does the scan mode include a timestamp
68 * @access: [DRIVER] buffer access functions associated with the
70 * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
71 * @scan_el_group: [DRIVER] attribute group for those attributes not
72 * created from the iio_chan_info array.
73 * @pollq: [INTERN] wait queue to allow for polling on the buffer.
74 * @stufftoread: [INTERN] flag to indicate new data.
75 * @demux_list: [INTERN] list of operations required to demux the scan.
76 * @demux_bounce: [INTERN] buffer for doing gather from incoming scan.
77 * @buffer_list: [INTERN] entry in the devices list of current buffers.
78 * @ref: [INTERN] reference count of the buffer.
83 struct attribute_group *scan_el_attrs;
86 const struct iio_buffer_access_funcs *access;
87 struct list_head scan_el_dev_attr_list;
88 struct attribute_group scan_el_group;
89 wait_queue_head_t pollq;
91 const struct attribute_group *attrs;
92 struct list_head demux_list;
94 struct list_head buffer_list;
99 * iio_update_buffers() - add or remove buffer from active list
100 * @indio_dev: device to add buffer to
101 * @insert_buffer: buffer to insert
102 * @remove_buffer: buffer_to_remove
104 * Note this will tear down the all buffering and build it up again
106 int iio_update_buffers(struct iio_dev *indio_dev,
107 struct iio_buffer *insert_buffer,
108 struct iio_buffer *remove_buffer);
111 * iio_buffer_init() - Initialize the buffer structure
112 * @buffer: buffer to be initialized
114 void iio_buffer_init(struct iio_buffer *buffer);
116 int iio_scan_mask_query(struct iio_dev *indio_dev,
117 struct iio_buffer *buffer, int bit);
120 * iio_push_to_buffers() - push to a registered buffer.
121 * @indio_dev: iio_dev structure for device.
124 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data);
127 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers
128 * @indio_dev: iio_dev structure for device.
130 * @timestamp: timestamp for the sample data
132 * Pushes data to the IIO device's buffers. If timestamps are enabled for the
133 * device the function will store the supplied timestamp as the last element in
134 * the sample data buffer before pushing it to the device buffers. The sample
135 * data buffer needs to be large enough to hold the additional timestamp
136 * (usually the buffer should be indio->scan_bytes bytes large).
138 * Returns 0 on success, a negative error code otherwise.
140 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev,
141 void *data, int64_t timestamp)
143 if (indio_dev->scan_timestamp) {
144 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1;
145 ((int64_t *)data)[ts_offset] = timestamp;
148 return iio_push_to_buffers(indio_dev, data);
151 int iio_update_demux(struct iio_dev *indio_dev);
154 * iio_buffer_register() - register the buffer with IIO core
155 * @indio_dev: device with the buffer to be registered
156 * @channels: the channel descriptions used to construct buffer
157 * @num_channels: the number of channels
159 int iio_buffer_register(struct iio_dev *indio_dev,
160 const struct iio_chan_spec *channels,
164 * iio_buffer_unregister() - unregister the buffer from IIO core
165 * @indio_dev: the device with the buffer to be unregistered
167 void iio_buffer_unregister(struct iio_dev *indio_dev);
170 * iio_buffer_read_length() - attr func to get number of datums in the buffer
172 ssize_t iio_buffer_read_length(struct device *dev,
173 struct device_attribute *attr,
176 * iio_buffer_write_length() - attr func to set number of datums in the buffer
178 ssize_t iio_buffer_write_length(struct device *dev,
179 struct device_attribute *attr,
183 * iio_buffer_store_enable() - attr to turn the buffer on
185 ssize_t iio_buffer_store_enable(struct device *dev,
186 struct device_attribute *attr,
190 * iio_buffer_show_enable() - attr to see if the buffer is on
192 ssize_t iio_buffer_show_enable(struct device *dev,
193 struct device_attribute *attr,
195 #define IIO_BUFFER_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR, \
196 iio_buffer_read_length, \
197 iio_buffer_write_length)
199 #define IIO_BUFFER_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, \
200 iio_buffer_show_enable, \
201 iio_buffer_store_enable)
203 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
204 const unsigned long *mask);
206 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
207 void iio_buffer_put(struct iio_buffer *buffer);
210 * iio_device_attach_buffer - Attach a buffer to a IIO device
211 * @indio_dev: The device the buffer should be attached to
212 * @buffer: The buffer to attach to the device
214 * This function attaches a buffer to a IIO device. The buffer stays attached to
215 * the device until the device is freed. The function should only be called at
216 * most once per device.
218 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev,
219 struct iio_buffer *buffer)
221 indio_dev->buffer = iio_buffer_get(buffer);
224 #else /* CONFIG_IIO_BUFFER */
226 static inline int iio_buffer_register(struct iio_dev *indio_dev,
227 const struct iio_chan_spec *channels,
233 static inline void iio_buffer_unregister(struct iio_dev *indio_dev)
236 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
237 static inline void iio_buffer_put(struct iio_buffer *buffer) {}
239 #endif /* CONFIG_IIO_BUFFER */
241 #endif /* _IIO_BUFFER_GENERIC_H_ */