1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _IIO_BUFFER_GENERIC_IMPL_H_
3 #define _IIO_BUFFER_GENERIC_IMPL_H_
4 #include <linux/sysfs.h>
5 #include <linux/kref.h>
6
7 #ifdef CONFIG_IIO_BUFFER
8
9 struct iio_dev;
10 struct iio_buffer;
11
12 /**
13 * INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be
14 * configured. It has a fixed value which will be buffer specific.
15 */
16 #define INDIO_BUFFER_FLAG_FIXED_WATERMARK BIT(0)
17
18 /**
19 * struct iio_buffer_access_funcs - access functions for buffers.
20 * @store_to: actually store stuff to the buffer
21 * @read_first_n: try to get a specified number of bytes (must exist)
22 * @data_available: indicates how much data is available for reading from
23 * the buffer.
24 * @request_update: if a parameter change has been marked, update underlying
25 * storage.
26 * @set_bytes_per_datum:set number of bytes per datum
27 * @set_length: set number of datums in buffer
28 * @enable: called if the buffer is attached to a device and the
29 * device starts sampling. Calls are balanced with
30 * @disable.
31 * @disable: called if the buffer is attached to a device and the
32 * device stops sampling. Calles are balanced with @enable.
33 * @release: called when the last reference to the buffer is dropped,
34 * should free all resources allocated by the buffer.
35 * @modes: Supported operating modes by this buffer type
36 * @flags: A bitmask combination of INDIO_BUFFER_FLAG_*
37 *
38 * The purpose of this structure is to make the buffer element
39 * modular as event for a given driver, different usecases may require
40 * different buffer designs (space efficiency vs speed for example).
41 *
42 * It is worth noting that a given buffer implementation may only support a
43 * small proportion of these functions. The core code 'should' cope fine with
44 * any of them not existing.
45 **/
46 struct iio_buffer_access_funcs {
47 int (*store_to)(struct iio_buffer *buffer, const void *data);
48 int (*read_first_n)(struct iio_buffer *buffer,
49 size_t n,
50 char __user *buf);
51 size_t (*data_available)(struct iio_buffer *buffer);
52
53 int (*request_update)(struct iio_buffer *buffer);
54
55 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
56 int (*set_length)(struct iio_buffer *buffer, unsigned int length);
57
58 int (*enable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
59 int (*disable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
60
61 void (*release)(struct iio_buffer *buffer);
62
63 unsigned int modes;
64 unsigned int flags;
65 };
66
67 /**
68 * struct iio_buffer - general buffer structure
69 *
70 * Note that the internals of this structure should only be of interest to
71 * those writing new buffer implementations.
72 */
73 struct iio_buffer {
74 /** @length: Number of datums in buffer. */
75 unsigned int length;
76
77 /** @bytes_per_datum: Size of individual datum including timestamp. */
78 size_t bytes_per_datum;
79
80 /**
81 * @access: Buffer access functions associated with the
82 * implementation.
83 */
84 const struct iio_buffer_access_funcs *access;
85
86 /** @scan_mask: Bitmask used in masking scan mode elements. */
87 long *scan_mask;
88
89 /** @demux_list: List of operations required to demux the scan. */
90 struct list_head demux_list;
91
92 /** @pollq: Wait queue to allow for polling on the buffer. */
93 wait_queue_head_t pollq;
94
95 /** @watermark: Number of datums to wait for poll/read. */
96 unsigned int watermark;
97
98 /* private: */
99 /*
100 * @scan_el_attrs: Control of scan elements if that scan mode
101 * control method is used.
102 */
103 struct attribute_group *scan_el_attrs;
104
105 /* @scan_timestamp: Does the scan mode include a timestamp. */
106 bool scan_timestamp;
107
108 /* @scan_el_dev_attr_list: List of scan element related attributes. */
109 struct list_head scan_el_dev_attr_list;
110
111 /* @buffer_group: Attributes of the buffer group. */
112 struct attribute_group buffer_group;
113
114 /*
115 * @scan_el_group: Attribute group for those attributes not
116 * created from the iio_chan_info array.
117 */
118 struct attribute_group scan_el_group;
119
120 /* @stufftoread: Flag to indicate new data. */
121 bool stufftoread;
122
123 /* @attrs: Standard attributes of the buffer. */
124 const struct attribute **attrs;
125
126 /* @demux_bounce: Buffer for doing gather from incoming scan. */
127 void *demux_bounce;
128
129 /* @buffer_list: Entry in the devices list of current buffers. */
130 struct list_head buffer_list;
131
132 /* @ref: Reference count of the buffer. */
133 struct kref ref;
134 };
135
136 /**
137 * iio_update_buffers() - add or remove buffer from active list
138 * @indio_dev: device to add buffer to
139 * @insert_buffer: buffer to insert
140 * @remove_buffer: buffer_to_remove
141 *
142 * Note this will tear down the all buffering and build it up again
143 */
144 int iio_update_buffers(struct iio_dev *indio_dev,
145 struct iio_buffer *insert_buffer,
146 struct iio_buffer *remove_buffer);
147
148 /**
149 * iio_buffer_init() - Initialize the buffer structure
150 * @buffer: buffer to be initialized
151 **/
152 void iio_buffer_init(struct iio_buffer *buffer);
153
154 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
155 void iio_buffer_put(struct iio_buffer *buffer);
156
157 #else /* CONFIG_IIO_BUFFER */
158
159 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
160 static inline void iio_buffer_put(struct iio_buffer *buffer) {}
161
162 #endif /* CONFIG_IIO_BUFFER */
163 #endif /* _IIO_BUFFER_GENERIC_IMPL_H_ */