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