1 /* The industrial I/O core - generic ring buffer interfaces.
3 * Copyright (c) 2008 Jonathan Cameron
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.
10 #ifndef _IIO_RING_GENERIC_H_
11 #define _IIO_RING_GENERIC_H_
15 #ifdef CONFIG_IIO_RING_BUFFER
17 struct iio_ring_buffer;
20 * struct iio_ring_access_funcs - access functions for ring buffers.
21 * @mark_in_use: reference counting, typically to prevent module removal
22 * @unmark_in_use: reduce reference count when no longer using ring buffer
23 * @store_to: actually store stuff to the ring 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 ring that some relevant parameter has changed
27 * Often this means the underlying storage may need to
29 * @request_update: if a parameter change has been marked, update underlying
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 ring
34 * @set_length: set number of datums in ring
35 * @is_enabled: query if ring is currently being used
36 * @enable: enable the ring
38 * The purpose of this structure is to make the ring buffer element
39 * modular as event for a given driver, different usecases may require
40 * different ring designs (space efficiency vs speed for example).
42 * It is worth noting that a given ring implementation may only support a small
43 * proportion of these functions. The core code 'should' cope fine with any of
46 struct iio_ring_access_funcs {
47 void (*mark_in_use)(struct iio_ring_buffer *ring);
48 void (*unmark_in_use)(struct iio_ring_buffer *ring);
50 int (*store_to)(struct iio_ring_buffer *ring, u8 *data, s64 timestamp);
51 int (*read_last)(struct iio_ring_buffer *ring, u8 *data);
52 int (*read_first_n)(struct iio_ring_buffer *ring,
56 int (*mark_param_change)(struct iio_ring_buffer *ring);
57 int (*request_update)(struct iio_ring_buffer *ring);
59 int (*get_bytes_per_datum)(struct iio_ring_buffer *ring);
60 int (*set_bytes_per_datum)(struct iio_ring_buffer *ring, size_t bpd);
61 int (*get_length)(struct iio_ring_buffer *ring);
62 int (*set_length)(struct iio_ring_buffer *ring, int length);
64 int (*is_enabled)(struct iio_ring_buffer *ring);
65 int (*enable)(struct iio_ring_buffer *ring);
69 * struct iio_ring_setup_ops - buffer setup related callbacks
70 * @preenable: [DRIVER] function to run prior to marking ring enabled
71 * @postenable: [DRIVER] function to run after marking ring enabled
72 * @predisable: [DRIVER] function to run prior to marking ring disabled
73 * @postdisable: [DRIVER] function to run after marking ring disabled
75 struct iio_ring_setup_ops {
76 int (*preenable)(struct iio_dev *);
77 int (*postenable)(struct iio_dev *);
78 int (*predisable)(struct iio_dev *);
79 int (*postdisable)(struct iio_dev *);
83 * struct iio_ring_buffer - general ring buffer structure
84 * @dev: ring buffer device struct
85 * @indio_dev: industrial I/O device structure
86 * @owner: module that owns the ring buffer (for ref counting)
87 * @length: [DEVICE] number of datums in ring
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] ring access functions associated with the
97 * @flags: [INTERN] file ops related flags including busy flag.
99 struct iio_ring_buffer {
100 struct iio_dev *indio_dev;
101 struct module *owner;
105 struct attribute_group *scan_el_attrs;
107 unsigned long scan_mask;
109 const struct iio_ring_access_funcs *access;
110 const struct iio_ring_setup_ops *setup_ops;
111 struct list_head scan_el_dev_attr_list;
113 wait_queue_head_t pollq;
116 const struct attribute_group *attrs;
120 * iio_ring_buffer_init() - Initialize the buffer structure
121 * @ring: buffer to be initialized
122 * @dev_info: the iio device the buffer is assocated with
124 void iio_ring_buffer_init(struct iio_ring_buffer *ring,
125 struct iio_dev *dev_info);
128 * __iio_update_ring_buffer() - update common elements of ring buffers
129 * @ring: ring buffer that is the event source
130 * @bytes_per_datum: size of individual datum including timestamp
131 * @length: number of datums in ring
133 static inline void __iio_update_ring_buffer(struct iio_ring_buffer *ring,
134 int bytes_per_datum, int length)
136 ring->bytes_per_datum = bytes_per_datum;
137 ring->length = length;
141 * These are mainly provided to allow for a change of implementation if a device
142 * has a large number of scan elements
144 #define IIO_MAX_SCAN_LENGTH 31
146 /* note 0 used as error indicator as it doesn't make sense. */
147 static inline u32 iio_scan_mask_match(u32 *av_masks, u32 mask)
150 if (!(~*av_masks & mask))
157 static inline int iio_scan_mask_query(struct iio_ring_buffer *ring, int bit)
159 struct iio_dev *dev_info = ring->indio_dev;
162 if (bit > IIO_MAX_SCAN_LENGTH)
165 if (!ring->scan_mask)
168 if (dev_info->available_scan_masks)
169 mask = iio_scan_mask_match(dev_info->available_scan_masks,
172 mask = ring->scan_mask;
177 return !!(mask & (1 << bit));
181 * iio_scan_mask_set() - set particular bit in the scan mask
182 * @ring: the ring buffer whose scan mask we are interested in
183 * @bit: the bit to be set.
185 static inline int iio_scan_mask_set(struct iio_ring_buffer *ring, int bit)
187 struct iio_dev *dev_info = ring->indio_dev;
189 u32 trialmask = ring->scan_mask | (1 << bit);
191 if (bit > IIO_MAX_SCAN_LENGTH)
193 if (dev_info->available_scan_masks) {
194 mask = iio_scan_mask_match(dev_info->available_scan_masks,
199 ring->scan_mask = trialmask;
205 #define to_iio_ring_buffer(d) \
206 container_of(d, struct iio_ring_buffer, dev)
209 * iio_ring_buffer_register() - register the buffer with IIO core
210 * @indio_dev: device with the buffer to be registered
212 int iio_ring_buffer_register(struct iio_dev *indio_dev,
213 const struct iio_chan_spec *channels,
217 * iio_ring_buffer_unregister() - unregister the buffer from IIO core
218 * @indio_dev: the device with the buffer to be unregistered
220 void iio_ring_buffer_unregister(struct iio_dev *indio_dev);
223 * iio_read_ring_length() - attr func to get number of datums in the buffer
225 ssize_t iio_read_ring_length(struct device *dev,
226 struct device_attribute *attr,
229 * iio_write_ring_length() - attr func to set number of datums in the buffer
231 ssize_t iio_write_ring_length(struct device *dev,
232 struct device_attribute *attr,
236 * iio_read_ring_bytes_per_datum() - attr for number of bytes in whole datum
238 ssize_t iio_read_ring_bytes_per_datum(struct device *dev,
239 struct device_attribute *attr,
242 * iio_store_ring_enable() - attr to turn the buffer on
244 ssize_t iio_store_ring_enable(struct device *dev,
245 struct device_attribute *attr,
249 * iio_show_ring_enable() - attr to see if the buffer is on
251 ssize_t iio_show_ring_enable(struct device *dev,
252 struct device_attribute *attr,
254 #define IIO_RING_LENGTH_ATTR DEVICE_ATTR(length, S_IRUGO | S_IWUSR, \
255 iio_read_ring_length, \
256 iio_write_ring_length)
257 #define IIO_RING_BYTES_PER_DATUM_ATTR DEVICE_ATTR(bytes_per_datum, S_IRUGO | S_IWUSR, \
258 iio_read_ring_bytes_per_datum, NULL)
259 #define IIO_RING_ENABLE_ATTR DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, \
260 iio_show_ring_enable, \
261 iio_store_ring_enable)
263 int iio_sw_ring_preenable(struct iio_dev *indio_dev);
265 #else /* CONFIG_IIO_RING_BUFFER */
267 static inline int iio_ring_buffer_register(struct iio_dev *indio_dev,
268 struct iio_chan_spec *channels,
274 static inline void iio_ring_buffer_unregister(struct iio_dev *indio_dev)
277 #endif /* CONFIG_IIO_RING_BUFFER */
279 #endif /* _IIO_RING_GENERIC_H_ */