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  *
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  **/
41 struct 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  */
77 struct 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  */
105 int 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  **/
113 void iio_buffer_init(struct iio_buffer *buffer);
114 
115 int 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  */
123 int 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  */
iio_push_to_buffers_with_timestamp(struct iio_dev * indio_dev,void * data,int64_t timestamp)139 static 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 
150 int iio_update_demux(struct iio_dev *indio_dev);
151 
152 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
153 	const unsigned long *mask);
154 
155 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
156 void 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  */
iio_device_attach_buffer(struct iio_dev * indio_dev,struct iio_buffer * buffer)167 static 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 
iio_buffer_get(struct iio_buffer * buffer)175 static inline void iio_buffer_get(struct iio_buffer *buffer) {}
iio_buffer_put(struct iio_buffer * buffer)176 static inline void iio_buffer_put(struct iio_buffer *buffer) {}
177 
178 #endif /* CONFIG_IIO_BUFFER */
179 
180 #endif /* _IIO_BUFFER_GENERIC_H_ */
181