buffer.h revision beb80600b017ff4c407e9e72eb7f9a884fed4210 
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 "iio.h"
14
15#ifdef CONFIG_IIO_BUFFER
16
17struct iio_buffer;
18
19/**
20 * struct iio_buffer_access_funcs - access functions for buffers.
21 * @mark_in_use:	reference counting, typically to prevent module removal
22 * @unmark_in_use:	reduce reference count when no longer using buffer
23 * @store_to:		actually store stuff to the buffer
24 * @read_last:		get the last element stored
25 * @read_first_n:	try to get a specified number of elements (must exist)
26 * @mark_param_change:	notify buffer that some relevant parameter has changed
27 *			Often this means the underlying storage may need to
28 *			change.
29 * @request_update:	if a parameter change has been marked, update underlying
30 *			storage.
31 * @get_bytes_per_datum:get current bytes per datum
32 * @set_bytes_per_datum:set number of bytes per datum
33 * @get_length:		get number of datums in buffer
34 * @set_length:		set number of datums in buffer
35 * @is_enabled:		query if buffer is currently being used
36 * @enable:		enable the buffer
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 **/
46struct iio_buffer_access_funcs {
47	void (*mark_in_use)(struct iio_buffer *buffer);
48	void (*unmark_in_use)(struct iio_buffer *buffer);
49
50	int (*store_to)(struct iio_buffer *buffer, u8 *data, s64 timestamp);
51	int (*read_last)(struct iio_buffer *buffer, u8 *data);
52	int (*read_first_n)(struct iio_buffer *buffer,
53			    size_t n,
54			    char __user *buf);
55
56	int (*mark_param_change)(struct iio_buffer *buffer);
57	int (*request_update)(struct iio_buffer *buffer);
58
59	int (*get_bytes_per_datum)(struct iio_buffer *buffer);
60	int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
61	int (*get_length)(struct iio_buffer *buffer);
62	int (*set_length)(struct iio_buffer *buffer, int length);
63
64	int (*is_enabled)(struct iio_buffer *buffer);
65	int (*enable)(struct iio_buffer *buffer);
66};
67
68/**
69 * struct iio_buffer_setup_ops - buffer setup related callbacks
70 * @preenable:		[DRIVER] function to run prior to marking buffer enabled
71 * @postenable:		[DRIVER] function to run after marking buffer enabled
72 * @predisable:		[DRIVER] function to run prior to marking buffer
73 *			disabled
74 * @postdisable:	[DRIVER] function to run after marking buffer disabled
75 */
76struct iio_buffer_setup_ops {
77	int				(*preenable)(struct iio_dev *);
78	int				(*postenable)(struct iio_dev *);
79	int				(*predisable)(struct iio_dev *);
80	int				(*postdisable)(struct iio_dev *);
81};
82
83/**
84 * struct iio_buffer - general buffer structure
85 * @indio_dev:		industrial I/O device structure
86 * @owner:		module that owns the buffer (for ref counting)
87 * @length:		[DEVICE] number of datums in buffer
88 * @bytes_per_datum:	[DEVICE] size of individual datum including timestamp
89 * @bpe:		[DEVICE] size of individual channel value
90 * @scan_el_attrs:	[DRIVER] control of scan elements if that scan mode
91 *			control method is used
92 * @scan_count:	[INTERN] the number of elements in the current scan mode
93 * @scan_mask:		[INTERN] bitmask used in masking scan mode elements
94 * @scan_timestamp:	[INTERN] does the scan mode include a timestamp
95 * @access:		[DRIVER] buffer access functions associated with the
96 *			implementation.
97 * @flags:		[INTERN] file ops related flags including busy flag.
98 **/
99struct iio_buffer {
100	struct iio_dev				*indio_dev;
101	struct module				*owner;
102	int					length;
103	int					bytes_per_datum;
104	int					bpe;
105	struct attribute_group			*scan_el_attrs;
106	int					scan_count;
107	long					*scan_mask;
108	bool					scan_timestamp;
109	unsigned				scan_index_timestamp;
110	const struct iio_buffer_access_funcs	*access;
111	const struct iio_buffer_setup_ops		*setup_ops;
112	struct list_head			scan_el_dev_attr_list;
113	struct attribute_group			scan_el_group;
114	wait_queue_head_t			pollq;
115	bool					stufftoread;
116	unsigned long				flags;
117	const struct attribute_group *attrs;
118};
119
120/**
121 * iio_buffer_init() - Initialize the buffer structure
122 * @buffer: buffer to be initialized
123 * @indio_dev: the iio device the buffer is assocated with
124 **/
125void iio_buffer_init(struct iio_buffer *buffer,
126			  struct iio_dev *indio_dev);
127
128void iio_buffer_deinit(struct iio_buffer *buffer);
129
130/**
131 * __iio_update_buffer() - update common elements of buffers
132 * @buffer:		buffer that is the event source
133 * @bytes_per_datum:	size of individual datum including timestamp
134 * @length:		number of datums in buffer
135 **/
136static inline void __iio_update_buffer(struct iio_buffer *buffer,
137				       int bytes_per_datum, int length)
138{
139	buffer->bytes_per_datum = bytes_per_datum;
140	buffer->length = length;
141}
142
143int iio_scan_mask_query(struct iio_buffer *buffer, int bit);
144
145/**
146 * iio_scan_mask_set() - set particular bit in the scan mask
147 * @buffer: the buffer whose scan mask we are interested in
148 * @bit: the bit to be set.
149 **/
150int iio_scan_mask_set(struct iio_buffer *buffer, int bit);
151
152#define to_iio_buffer(d)				\
153	container_of(d, struct iio_buffer, dev)
154
155/**
156 * iio_buffer_register() - register the buffer with IIO core
157 * @indio_dev: device with the buffer to be registered
158 **/
159int iio_buffer_register(struct iio_dev *indio_dev,
160			const struct iio_chan_spec *channels,
161			int num_channels);
162
163/**
164 * iio_buffer_unregister() - unregister the buffer from IIO core
165 * @indio_dev: the device with the buffer to be unregistered
166 **/
167void iio_buffer_unregister(struct iio_dev *indio_dev);
168
169/**
170 * iio_buffer_read_length() - attr func to get number of datums in the buffer
171 **/
172ssize_t iio_buffer_read_length(struct device *dev,
173			       struct device_attribute *attr,
174			       char *buf);
175/**
176 * iio_buffer_write_length() - attr func to set number of datums in the buffer
177 **/
178ssize_t iio_buffer_write_length(struct device *dev,
179			      struct device_attribute *attr,
180			      const char *buf,
181			      size_t len);
182/**
183 * iio_buffer_read_bytes_per_datum() - attr for number of bytes in whole datum
184 **/
185ssize_t iio_buffer_read_bytes_per_datum(struct device *dev,
186					struct device_attribute *attr,
187					char *buf);
188/**
189 * iio_buffer_store_enable() - attr to turn the buffer on
190 **/
191ssize_t iio_buffer_store_enable(struct device *dev,
192				struct device_attribute *attr,
193				const char *buf,
194				size_t len);
195/**
196 * iio_buffer_show_enable() - attr to see if the buffer is on
197 **/
198ssize_t iio_buffer_show_enable(struct device *dev,
199			       struct device_attribute *attr,
200			       char *buf);
201#define IIO_BUFFER_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR,	\
202					   iio_buffer_read_length,	\
203					   iio_buffer_write_length)
204#define IIO_BUFFER_BYTES_PER_DATUM_ATTR					\
205	DEVICE_ATTR(bytes_per_datum, S_IRUGO | S_IWUSR,			\
206		    iio_buffer_read_bytes_per_datum, NULL)
207
208#define IIO_BUFFER_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,	\
209					   iio_buffer_show_enable,	\
210					   iio_buffer_store_enable)
211
212int iio_sw_buffer_preenable(struct iio_dev *indio_dev);
213
214#else /* CONFIG_IIO_BUFFER */
215
216static inline int iio_buffer_register(struct iio_dev *indio_dev,
217					   struct iio_chan_spec *channels,
218					   int num_channels)
219{
220	return 0;
221}
222
223static inline void iio_buffer_unregister(struct iio_dev *indio_dev)
224{};
225
226#endif /* CONFIG_IIO_BUFFER */
227
228#endif /* _IIO_BUFFER_GENERIC_H_ */
229