1/* The industrial I/O core - generic buffer interfaces.
2 *
3 * Copyright (c) 2008 Jonathan Cameron
4 *
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.
8 */
9
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>
15
16#ifdef CONFIG_IIO_BUFFER
17
18struct iio_buffer;
19
20/**
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 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 * @release:		called when the last reference to the buffer is dropped,
31 *			should free all resources allocated by the buffer.
32 *
33 * The purpose of this structure is to make the buffer element
34 * modular as event for a given driver, different usecases may require
35 * different buffer designs (space efficiency vs speed for example).
36 *
37 * It is worth noting that a given buffer implementation may only support a
38 * small proportion of these functions.  The core code 'should' cope fine with
39 * any of them not existing.
40 **/
41struct iio_buffer_access_funcs {
42	int (*store_to)(struct iio_buffer *buffer, const void *data);
43	int (*read_first_n)(struct iio_buffer *buffer,
44			    size_t n,
45			    char __user *buf);
46	size_t (*data_available)(struct iio_buffer *buffer);
47
48	int (*request_update)(struct iio_buffer *buffer);
49
50	int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
51	int (*set_length)(struct iio_buffer *buffer, int length);
52
53	void (*release)(struct iio_buffer *buffer);
54};
55
56/**
57 * struct iio_buffer - general buffer structure
58 * @length:		[DEVICE] number of datums in buffer
59 * @bytes_per_datum:	[DEVICE] size of individual datum including timestamp
60 * @scan_el_attrs:	[DRIVER] control of scan elements if that scan mode
61 *			control method is used
62 * @scan_mask:		[INTERN] bitmask used in masking scan mode elements
63 * @scan_timestamp:	[INTERN] does the scan mode include a timestamp
64 * @access:		[DRIVER] buffer access functions associated with the
65 *			implementation.
66 * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
67 * @scan_el_group:	[DRIVER] attribute group for those attributes not
68 *			created from the iio_chan_info array.
69 * @pollq:		[INTERN] wait queue to allow for polling on the buffer.
70 * @stufftoread:	[INTERN] flag to indicate new data.
71 * @demux_list:		[INTERN] list of operations required to demux the scan.
72 * @demux_bounce:	[INTERN] buffer for doing gather from incoming scan.
73 * @buffer_list:	[INTERN] entry in the devices list of current buffers.
74 * @ref:		[INTERN] reference count of the buffer.
75 * @watermark:		[INTERN] number of datums to wait for poll/read.
76 */
77struct iio_buffer {
78	int					length;
79	int					bytes_per_datum;
80	struct attribute_group			*scan_el_attrs;
81	long					*scan_mask;
82	bool					scan_timestamp;
83	const struct iio_buffer_access_funcs	*access;
84	struct list_head			scan_el_dev_attr_list;
85	struct attribute_group			buffer_group;
86	struct attribute_group			scan_el_group;
87	wait_queue_head_t			pollq;
88	bool					stufftoread;
89	const struct attribute			**attrs;
90	struct list_head			demux_list;
91	void					*demux_bounce;
92	struct list_head			buffer_list;
93	struct kref				ref;
94	unsigned int				watermark;
95};
96
97/**
98 * iio_update_buffers() - add or remove buffer from active list
99 * @indio_dev:		device to add buffer to
100 * @insert_buffer:	buffer to insert
101 * @remove_buffer:	buffer_to_remove
102 *
103 * Note this will tear down the all buffering and build it up again
104 */
105int iio_update_buffers(struct iio_dev *indio_dev,
106		       struct iio_buffer *insert_buffer,
107		       struct iio_buffer *remove_buffer);
108
109/**
110 * iio_buffer_init() - Initialize the buffer structure
111 * @buffer:		buffer to be initialized
112 **/
113void iio_buffer_init(struct iio_buffer *buffer);
114
115int iio_scan_mask_query(struct iio_dev *indio_dev,
116			struct iio_buffer *buffer, int bit);
117
118/**
119 * iio_push_to_buffers() - push to a registered buffer.
120 * @indio_dev:		iio_dev structure for device.
121 * @data:		Full scan.
122 */
123int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data);
124
125/*
126 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers
127 * @indio_dev:		iio_dev structure for device.
128 * @data:		sample data
129 * @timestamp:		timestamp for the sample data
130 *
131 * Pushes data to the IIO device's buffers. If timestamps are enabled for the
132 * device the function will store the supplied timestamp as the last element in
133 * the sample data buffer before pushing it to the device buffers. The sample
134 * data buffer needs to be large enough to hold the additional timestamp
135 * (usually the buffer should be indio->scan_bytes bytes large).
136 *
137 * Returns 0 on success, a negative error code otherwise.
138 */
139static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev,
140	void *data, int64_t timestamp)
141{
142	if (indio_dev->scan_timestamp) {
143		size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1;
144		((int64_t *)data)[ts_offset] = timestamp;
145	}
146
147	return iio_push_to_buffers(indio_dev, data);
148}
149
150int iio_update_demux(struct iio_dev *indio_dev);
151
152bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
153	const unsigned long *mask);
154
155struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
156void iio_buffer_put(struct iio_buffer *buffer);
157
158/**
159 * iio_device_attach_buffer - Attach a buffer to a IIO device
160 * @indio_dev: The device the buffer should be attached to
161 * @buffer: The buffer to attach to the device
162 *
163 * This function attaches a buffer to a IIO device. The buffer stays attached to
164 * the device until the device is freed. The function should only be called at
165 * most once per device.
166 */
167static inline void iio_device_attach_buffer(struct iio_dev *indio_dev,
168	struct iio_buffer *buffer)
169{
170	indio_dev->buffer = iio_buffer_get(buffer);
171}
172
173#else /* CONFIG_IIO_BUFFER */
174
175static inline void iio_buffer_get(struct iio_buffer *buffer) {}
176static inline void iio_buffer_put(struct iio_buffer *buffer) {}
177
178#endif /* CONFIG_IIO_BUFFER */
179
180#endif /* _IIO_BUFFER_GENERIC_H_ */
181