xref: /openbmc/linux/include/linux/iio/buffer_impl.h (revision 0a33755c)
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 #include <linux/iio/buffer.h>
11 
12 struct iio_dev;
13 struct iio_buffer;
14 
15 /**
16  * INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be
17  *   configured. It has a fixed value which will be buffer specific.
18  */
19 #define INDIO_BUFFER_FLAG_FIXED_WATERMARK BIT(0)
20 
21 /**
22  * struct iio_buffer_access_funcs - access functions for buffers.
23  * @store_to:		actually store stuff to the buffer
24  * @read:		try to get a specified number of bytes (must exist)
25  * @data_available:	indicates how much data is available for reading from
26  *			the buffer.
27  * @remove_from:	remove scan from buffer. Drivers should calls this to
28  *			remove a scan from a buffer.
29  * @write:		try to write a number of bytes
30  * @space_available:	returns the amount of bytes available in a buffer
31  * @request_update:	if a parameter change has been marked, update underlying
32  *			storage.
33  * @set_bytes_per_datum:set number of bytes per datum
34  * @set_length:		set number of datums in buffer
35  * @enable:             called if the buffer is attached to a device and the
36  *                      device starts sampling. Calls are balanced with
37  *                      @disable.
38  * @disable:            called if the buffer is attached to a device and the
39  *                      device stops sampling. Calles are balanced with @enable.
40  * @release:		called when the last reference to the buffer is dropped,
41  *			should free all resources allocated by the buffer.
42  * @modes:		Supported operating modes by this buffer type
43  * @flags:		A bitmask combination of INDIO_BUFFER_FLAG_*
44  *
45  * The purpose of this structure is to make the buffer element
46  * modular as event for a given driver, different usecases may require
47  * different buffer designs (space efficiency vs speed for example).
48  *
49  * It is worth noting that a given buffer implementation may only support a
50  * small proportion of these functions.  The core code 'should' cope fine with
51  * any of them not existing.
52  **/
53 struct iio_buffer_access_funcs {
54 	int (*store_to)(struct iio_buffer *buffer, const void *data);
55 	int (*read)(struct iio_buffer *buffer, size_t n, char __user *buf);
56 	size_t (*data_available)(struct iio_buffer *buffer);
57 	int (*remove_from)(struct iio_buffer *buffer, void *data);
58 	int (*write)(struct iio_buffer *buffer, size_t n, const char __user *buf);
59 	size_t (*space_available)(struct iio_buffer *buffer);
60 
61 	int (*request_update)(struct iio_buffer *buffer);
62 
63 	int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
64 	int (*set_length)(struct iio_buffer *buffer, unsigned int length);
65 
66 	int (*enable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
67 	int (*disable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
68 
69 	void (*release)(struct iio_buffer *buffer);
70 
71 	unsigned int modes;
72 	unsigned int flags;
73 };
74 
75 /**
76  * struct iio_buffer - general buffer structure
77  *
78  * Note that the internals of this structure should only be of interest to
79  * those writing new buffer implementations.
80  */
81 struct iio_buffer {
82 	/** @length: Number of datums in buffer. */
83 	unsigned int length;
84 
85 	/** @flags: File ops flags including busy flag. */
86 	unsigned long flags;
87 
88 	/**  @bytes_per_datum: Size of individual datum including timestamp. */
89 	size_t bytes_per_datum;
90 
91 	/* @direction: Direction of the data stream (in/out). */
92 	enum iio_buffer_direction direction;
93 
94 	/**
95 	 * @access: Buffer access functions associated with the
96 	 * implementation.
97 	 */
98 	const struct iio_buffer_access_funcs *access;
99 
100 	/** @scan_mask: Bitmask used in masking scan mode elements. */
101 	long *scan_mask;
102 
103 	/** @demux_list: List of operations required to demux the scan. */
104 	struct list_head demux_list;
105 
106 	/** @pollq: Wait queue to allow for polling on the buffer. */
107 	wait_queue_head_t pollq;
108 
109 	/** @watermark: Number of datums to wait for poll/read. */
110 	unsigned int watermark;
111 
112 	/* private: */
113 	/* @scan_timestamp: Does the scan mode include a timestamp. */
114 	bool scan_timestamp;
115 
116 	/* @buffer_attr_list: List of buffer attributes. */
117 	struct list_head buffer_attr_list;
118 
119 	/*
120 	 * @buffer_group: Attributes of the new buffer group.
121 	 * Includes scan elements attributes.
122 	 */
123 	struct attribute_group buffer_group;
124 
125 	/* @attrs: Standard attributes of the buffer. */
126 	const struct iio_dev_attr **attrs;
127 
128 	/* @demux_bounce: Buffer for doing gather from incoming scan. */
129 	void *demux_bounce;
130 
131 	/* @attached_entry: Entry in the devices list of buffers attached by the driver. */
132 	struct list_head attached_entry;
133 
134 	/* @buffer_list: Entry in the devices list of current buffers. */
135 	struct list_head buffer_list;
136 
137 	/* @ref: Reference count of the buffer. */
138 	struct kref ref;
139 };
140 
141 /**
142  * iio_update_buffers() - add or remove buffer from active list
143  * @indio_dev:		device to add buffer to
144  * @insert_buffer:	buffer to insert
145  * @remove_buffer:	buffer_to_remove
146  *
147  * Note this will tear down the all buffering and build it up again
148  */
149 int iio_update_buffers(struct iio_dev *indio_dev,
150 		       struct iio_buffer *insert_buffer,
151 		       struct iio_buffer *remove_buffer);
152 
153 /**
154  * iio_buffer_init() - Initialize the buffer structure
155  * @buffer:		buffer to be initialized
156  **/
157 void iio_buffer_init(struct iio_buffer *buffer);
158 
159 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
160 void iio_buffer_put(struct iio_buffer *buffer);
161 
162 #else /* CONFIG_IIO_BUFFER */
163 
iio_buffer_get(struct iio_buffer * buffer)164 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
iio_buffer_put(struct iio_buffer * buffer)165 static inline void iio_buffer_put(struct iio_buffer *buffer) {}
166 
167 #endif /* CONFIG_IIO_BUFFER */
168 #endif /* _IIO_BUFFER_GENERIC_IMPL_H_ */
169