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
18 struct 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 * @modes: Supported operating modes by this buffer type
33 *
34 * The purpose of this structure is to make the buffer element
35 * modular as event for a given driver, different usecases may require
36 * different buffer designs (space efficiency vs speed for example).
37 *
38 * It is worth noting that a given buffer implementation may only support a
39 * small proportion of these functions. The core code 'should' cope fine with
40 * any of them not existing.
41 **/
42 struct iio_buffer_access_funcs {
43 int (*store_to)(struct iio_buffer *buffer, const void *data);
44 int (*read_first_n)(struct iio_buffer *buffer,
45 size_t n,
46 char __user *buf);
47 size_t (*data_available)(struct iio_buffer *buffer);
48
49 int (*request_update)(struct iio_buffer *buffer);
50
51 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
52 int (*set_length)(struct iio_buffer *buffer, unsigned int length);
53
54 void (*release)(struct iio_buffer *buffer);
55
56 unsigned int modes;
57 };
58
59 /**
60 * struct iio_buffer - general buffer structure
61 * @length: [DEVICE] number of datums in buffer
62 * @bytes_per_datum: [DEVICE] size of individual datum including timestamp
63 * @scan_el_attrs: [DRIVER] control of scan elements if that scan mode
64 * control method is used
65 * @scan_mask: [INTERN] bitmask used in masking scan mode elements
66 * @scan_timestamp: [INTERN] does the scan mode include a timestamp
67 * @access: [DRIVER] buffer access functions associated with the
68 * implementation.
69 * @scan_el_dev_attr_list:[INTERN] list of scan element related attributes.
70 * @scan_el_group: [DRIVER] attribute group for those attributes not
71 * created from the iio_chan_info array.
72 * @pollq: [INTERN] wait queue to allow for polling on the buffer.
73 * @stufftoread: [INTERN] flag to indicate new data.
74 * @demux_list: [INTERN] list of operations required to demux the scan.
75 * @demux_bounce: [INTERN] buffer for doing gather from incoming scan.
76 * @buffer_list: [INTERN] entry in the devices list of current buffers.
77 * @ref: [INTERN] reference count of the buffer.
78 * @watermark: [INTERN] number of datums to wait for poll/read.
79 */
80 struct iio_buffer {
81 unsigned int length;
82 size_t bytes_per_datum;
83 struct attribute_group *scan_el_attrs;
84 long *scan_mask;
85 bool scan_timestamp;
86 const struct iio_buffer_access_funcs *access;
87 struct list_head scan_el_dev_attr_list;
88 struct attribute_group buffer_group;
89 struct attribute_group scan_el_group;
90 wait_queue_head_t pollq;
91 bool stufftoread;
92 const struct attribute **attrs;
93 struct list_head demux_list;
94 void *demux_bounce;
95 struct list_head buffer_list;
96 struct kref ref;
97 unsigned int watermark;
98 };
99
100 /**
101 * iio_update_buffers() - add or remove buffer from active list
102 * @indio_dev: device to add buffer to
103 * @insert_buffer: buffer to insert
104 * @remove_buffer: buffer_to_remove
105 *
106 * Note this will tear down the all buffering and build it up again
107 */
108 int iio_update_buffers(struct iio_dev *indio_dev,
109 struct iio_buffer *insert_buffer,
110 struct iio_buffer *remove_buffer);
111
112 /**
113 * iio_buffer_init() - Initialize the buffer structure
114 * @buffer: buffer to be initialized
115 **/
116 void iio_buffer_init(struct iio_buffer *buffer);
117
118 int iio_scan_mask_query(struct iio_dev *indio_dev,
119 struct iio_buffer *buffer, int bit);
120
121 /**
122 * iio_push_to_buffers() - push to a registered buffer.
123 * @indio_dev: iio_dev structure for device.
124 * @data: Full scan.
125 */
126 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data);
127
128 /*
129 * iio_push_to_buffers_with_timestamp() - push data and timestamp to buffers
130 * @indio_dev: iio_dev structure for device.
131 * @data: sample data
132 * @timestamp: timestamp for the sample data
133 *
134 * Pushes data to the IIO device's buffers. If timestamps are enabled for the
135 * device the function will store the supplied timestamp as the last element in
136 * the sample data buffer before pushing it to the device buffers. The sample
137 * data buffer needs to be large enough to hold the additional timestamp
138 * (usually the buffer should be indio->scan_bytes bytes large).
139 *
140 * Returns 0 on success, a negative error code otherwise.
141 */
iio_push_to_buffers_with_timestamp(struct iio_dev * indio_dev,void * data,int64_t timestamp)142 static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev,
143 void *data, int64_t timestamp)
144 {
145 if (indio_dev->scan_timestamp) {
146 size_t ts_offset = indio_dev->scan_bytes / sizeof(int64_t) - 1;
147 ((int64_t *)data)[ts_offset] = timestamp;
148 }
149
150 return iio_push_to_buffers(indio_dev, data);
151 }
152
153 int iio_update_demux(struct iio_dev *indio_dev);
154
155 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
156 const unsigned long *mask);
157
158 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
159 void iio_buffer_put(struct iio_buffer *buffer);
160
161 /**
162 * iio_device_attach_buffer - Attach a buffer to a IIO device
163 * @indio_dev: The device the buffer should be attached to
164 * @buffer: The buffer to attach to the device
165 *
166 * This function attaches a buffer to a IIO device. The buffer stays attached to
167 * the device until the device is freed. The function should only be called at
168 * most once per device.
169 */
iio_device_attach_buffer(struct iio_dev * indio_dev,struct iio_buffer * buffer)170 static inline void iio_device_attach_buffer(struct iio_dev *indio_dev,
171 struct iio_buffer *buffer)
172 {
173 indio_dev->buffer = iio_buffer_get(buffer);
174 }
175
176 #else /* CONFIG_IIO_BUFFER */
177
iio_buffer_get(struct iio_buffer * buffer)178 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
iio_buffer_put(struct iio_buffer * buffer)179 static inline void iio_buffer_put(struct iio_buffer *buffer) {}
180
181 #endif /* CONFIG_IIO_BUFFER */
182
183 #endif /* _IIO_BUFFER_GENERIC_H_ */
184