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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _IIO_BUFFER_GENERIC_IMPL_H_
3#define _IIO_BUFFER_GENERIC_IMPL_H_
4#include <linux/sysfs.h>
5#include <linux/kref.h>
6
7#ifdef CONFIG_IIO_BUFFER
8
9#include <uapi/linux/iio/buffer.h>
10#include <linux/iio/buffer.h>
11
12struct dma_buf_attachment;
13struct dma_fence;
14struct iio_dev;
15struct iio_dma_buffer_block;
16struct iio_buffer;
17struct sg_table;
18
19/**
20 * INDIO_BUFFER_FLAG_FIXED_WATERMARK - Watermark level of the buffer can not be
21 * configured. It has a fixed value which will be buffer specific.
22 */
23#define INDIO_BUFFER_FLAG_FIXED_WATERMARK BIT(0)
24
25/**
26 * struct iio_buffer_access_funcs - access functions for buffers.
27 * @store_to: actually store stuff to the buffer
28 * @read: try to get a specified number of bytes (must exist)
29 * @data_available: indicates how much data is available for reading from
30 * the buffer.
31 * @remove_from: remove scan from buffer. Drivers should calls this to
32 * remove a scan from a buffer.
33 * @write: try to write a number of bytes
34 * @space_available: returns the amount of bytes available in a buffer
35 * @request_update: if a parameter change has been marked, update underlying
36 * storage.
37 * @set_bytes_per_datum:set number of bytes per datum
38 * @set_length: set number of datums in buffer
39 * @enable: called if the buffer is attached to a device and the
40 * device starts sampling. Calls are balanced with
41 * @disable.
42 * @disable: called if the buffer is attached to a device and the
43 * device stops sampling. Calles are balanced with @enable.
44 * @release: called when the last reference to the buffer is dropped,
45 * should free all resources allocated by the buffer.
46 * @attach_dmabuf: called from userspace via ioctl to attach one external
47 * DMABUF.
48 * @detach_dmabuf: called from userspace via ioctl to detach one previously
49 * attached DMABUF.
50 * @enqueue_dmabuf: called from userspace via ioctl to queue this DMABUF
51 * object to this buffer. Requires a valid DMABUF fd, that
52 * was previouly attached to this buffer.
53 * @get_dma_dev: called to get the DMA channel associated with this buffer.
54 * @lock_queue: called when the core needs to lock the buffer queue;
55 * it is used when enqueueing DMABUF objects.
56 * @unlock_queue: used to unlock a previously locked buffer queue
57 * @modes: Supported operating modes by this buffer type
58 * @flags: A bitmask combination of INDIO_BUFFER_FLAG_*
59 *
60 * The purpose of this structure is to make the buffer element
61 * modular as event for a given driver, different usecases may require
62 * different buffer designs (space efficiency vs speed for example).
63 *
64 * It is worth noting that a given buffer implementation may only support a
65 * small proportion of these functions. The core code 'should' cope fine with
66 * any of them not existing.
67 **/
68struct iio_buffer_access_funcs {
69 int (*store_to)(struct iio_buffer *buffer, const void *data);
70 int (*read)(struct iio_buffer *buffer, size_t n, char __user *buf);
71 size_t (*data_available)(struct iio_buffer *buffer);
72 int (*remove_from)(struct iio_buffer *buffer, void *data);
73 int (*write)(struct iio_buffer *buffer, size_t n, const char __user *buf);
74 size_t (*space_available)(struct iio_buffer *buffer);
75
76 int (*request_update)(struct iio_buffer *buffer);
77
78 int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
79 int (*set_length)(struct iio_buffer *buffer, unsigned int length);
80
81 int (*enable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
82 int (*disable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
83
84 void (*release)(struct iio_buffer *buffer);
85
86 struct iio_dma_buffer_block * (*attach_dmabuf)(struct iio_buffer *buffer,
87 struct dma_buf_attachment *attach);
88 void (*detach_dmabuf)(struct iio_buffer *buffer,
89 struct iio_dma_buffer_block *block);
90 int (*enqueue_dmabuf)(struct iio_buffer *buffer,
91 struct iio_dma_buffer_block *block,
92 struct dma_fence *fence, struct sg_table *sgt,
93 size_t size, bool cyclic);
94 struct device * (*get_dma_dev)(struct iio_buffer *buffer);
95 void (*lock_queue)(struct iio_buffer *buffer);
96 void (*unlock_queue)(struct iio_buffer *buffer);
97
98 unsigned int modes;
99 unsigned int flags;
100};
101
102/**
103 * struct iio_buffer - general buffer structure
104 *
105 * Note that the internals of this structure should only be of interest to
106 * those writing new buffer implementations.
107 */
108struct iio_buffer {
109 /** @length: Number of datums in buffer. */
110 unsigned int length;
111
112 /** @flags: File ops flags including busy flag. */
113 unsigned long flags;
114
115 /** @bytes_per_datum: Size of individual datum including timestamp. */
116 size_t bytes_per_datum;
117
118 /* @direction: Direction of the data stream (in/out). */
119 enum iio_buffer_direction direction;
120
121 /**
122 * @access: Buffer access functions associated with the
123 * implementation.
124 */
125 const struct iio_buffer_access_funcs *access;
126
127 /** @scan_mask: Bitmask used in masking scan mode elements. */
128 long *scan_mask;
129
130 /** @demux_list: List of operations required to demux the scan. */
131 struct list_head demux_list;
132
133 /** @pollq: Wait queue to allow for polling on the buffer. */
134 wait_queue_head_t pollq;
135
136 /** @watermark: Number of datums to wait for poll/read. */
137 unsigned int watermark;
138
139 /* private: */
140 /* @scan_timestamp: Does the scan mode include a timestamp. */
141 bool scan_timestamp;
142
143 /* @buffer_attr_list: List of buffer attributes. */
144 struct list_head buffer_attr_list;
145
146 /*
147 * @buffer_group: Attributes of the new buffer group.
148 * Includes scan elements attributes.
149 */
150 struct attribute_group buffer_group;
151
152 /* @attrs: Standard attributes of the buffer. */
153 const struct iio_dev_attr **attrs;
154
155 /* @demux_bounce: Buffer for doing gather from incoming scan. */
156 void *demux_bounce;
157
158 /* @attached_entry: Entry in the devices list of buffers attached by the driver. */
159 struct list_head attached_entry;
160
161 /* @buffer_list: Entry in the devices list of current buffers. */
162 struct list_head buffer_list;
163
164 /* @ref: Reference count of the buffer. */
165 struct kref ref;
166
167 /* @dmabufs: List of DMABUF attachments */
168 struct list_head dmabufs; /* P: dmabufs_mutex */
169
170 /* @dmabufs_mutex: Protects dmabufs */
171 struct mutex dmabufs_mutex;
172};
173
174/**
175 * iio_update_buffers() - add or remove buffer from active list
176 * @indio_dev: device to add buffer to
177 * @insert_buffer: buffer to insert
178 * @remove_buffer: buffer_to_remove
179 *
180 * Note this will tear down the all buffering and build it up again
181 */
182int iio_update_buffers(struct iio_dev *indio_dev,
183 struct iio_buffer *insert_buffer,
184 struct iio_buffer *remove_buffer);
185
186/**
187 * iio_buffer_init() - Initialize the buffer structure
188 * @buffer: buffer to be initialized
189 **/
190void iio_buffer_init(struct iio_buffer *buffer);
191
192struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer);
193void iio_buffer_put(struct iio_buffer *buffer);
194
195void iio_buffer_signal_dmabuf_done(struct dma_fence *fence, int ret);
196
197#else /* CONFIG_IIO_BUFFER */
198
199static inline void iio_buffer_get(struct iio_buffer *buffer) {}
200static inline void iio_buffer_put(struct iio_buffer *buffer) {}
201
202#endif /* CONFIG_IIO_BUFFER */
203#endif /* _IIO_BUFFER_GENERIC_IMPL_H_ */