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 
iio_buffer_get(struct iio_buffer * buffer)159 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
iio_buffer_put(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_ */
164