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