buffer_impl.h

  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_ */