1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * Copyright 2013-2015 Analog Devices Inc.
4  *  Author: Lars-Peter Clausen <lars@metafoo.de>
5  */
6 
7 #ifndef __INDUSTRIALIO_DMA_BUFFER_H__
8 #define __INDUSTRIALIO_DMA_BUFFER_H__
9 
10 #include <linux/list.h>
11 #include <linux/kref.h>
12 #include <linux/spinlock.h>
13 #include <linux/mutex.h>
14 #include <linux/iio/buffer_impl.h>
15 
16 struct iio_dma_buffer_queue;
17 struct iio_dma_buffer_ops;
18 struct device;
19 
20 /**
21  * enum iio_block_state - State of a struct iio_dma_buffer_block
22  * @IIO_BLOCK_STATE_QUEUED: Block is on the incoming queue
23  * @IIO_BLOCK_STATE_ACTIVE: Block is currently being processed by the DMA
24  * @IIO_BLOCK_STATE_DONE: Block is on the outgoing queue
25  * @IIO_BLOCK_STATE_DEAD: Block has been marked as to be freed
26  */
27 enum iio_block_state {
28 	IIO_BLOCK_STATE_QUEUED,
29 	IIO_BLOCK_STATE_ACTIVE,
30 	IIO_BLOCK_STATE_DONE,
31 	IIO_BLOCK_STATE_DEAD,
32 };
33 
34 /**
35  * struct iio_dma_buffer_block - IIO buffer block
36  * @head: List head
37  * @size: Total size of the block in bytes
38  * @bytes_used: Number of bytes that contain valid data
39  * @vaddr: Virutal address of the blocks memory
40  * @phys_addr: Physical address of the blocks memory
41  * @queue: Parent DMA buffer queue
42  * @kref: kref used to manage the lifetime of block
43  * @state: Current state of the block
44  */
45 struct iio_dma_buffer_block {
46 	/* May only be accessed by the owner of the block */
47 	struct list_head head;
48 	size_t bytes_used;
49 
50 	/*
51 	 * Set during allocation, constant thereafter. May be accessed read-only
52 	 * by anybody holding a reference to the block.
53 	 */
54 	void *vaddr;
55 	dma_addr_t phys_addr;
56 	size_t size;
57 	struct iio_dma_buffer_queue *queue;
58 
59 	/* Must not be accessed outside the core. */
60 	struct kref kref;
61 	/*
62 	 * Must not be accessed outside the core. Access needs to hold
63 	 * queue->list_lock if the block is not owned by the core.
64 	 */
65 	enum iio_block_state state;
66 };
67 
68 /**
69  * struct iio_dma_buffer_queue_fileio - FileIO state for the DMA buffer
70  * @blocks: Buffer blocks used for fileio
71  * @active_block: Block being used in read()
72  * @pos: Read offset in the active block
73  * @block_size: Size of each block
74  * @next_dequeue: index of next block that will be dequeued
75  */
76 struct iio_dma_buffer_queue_fileio {
77 	struct iio_dma_buffer_block *blocks[2];
78 	struct iio_dma_buffer_block *active_block;
79 	size_t pos;
80 	size_t block_size;
81 
82 	unsigned int next_dequeue;
83 };
84 
85 /**
86  * struct iio_dma_buffer_queue - DMA buffer base structure
87  * @buffer: IIO buffer base structure
88  * @dev: Parent device
89  * @ops: DMA buffer callbacks
90  * @lock: Protects the incoming list, active and the fields in the fileio
91  *   substruct
92  * @list_lock: Protects lists that contain blocks which can be modified in
93  *   atomic context as well as blocks on those lists. This is the outgoing queue
94  *   list and typically also a list of active blocks in the part that handles
95  *   the DMA controller
96  * @incoming: List of buffers on the incoming queue
97  * @active: Whether the buffer is currently active
98  * @fileio: FileIO state
99  */
100 struct iio_dma_buffer_queue {
101 	struct iio_buffer buffer;
102 	struct device *dev;
103 	const struct iio_dma_buffer_ops *ops;
104 
105 	struct mutex lock;
106 	spinlock_t list_lock;
107 	struct list_head incoming;
108 
109 	bool active;
110 
111 	struct iio_dma_buffer_queue_fileio fileio;
112 };
113 
114 /**
115  * struct iio_dma_buffer_ops - DMA buffer callback operations
116  * @submit: Called when a block is submitted to the DMA controller
117  * @abort: Should abort all pending transfers
118  */
119 struct iio_dma_buffer_ops {
120 	int (*submit)(struct iio_dma_buffer_queue *queue,
121 		struct iio_dma_buffer_block *block);
122 	void (*abort)(struct iio_dma_buffer_queue *queue);
123 };
124 
125 void iio_dma_buffer_block_done(struct iio_dma_buffer_block *block);
126 void iio_dma_buffer_block_list_abort(struct iio_dma_buffer_queue *queue,
127 	struct list_head *list);
128 
129 int iio_dma_buffer_enable(struct iio_buffer *buffer,
130 	struct iio_dev *indio_dev);
131 int iio_dma_buffer_disable(struct iio_buffer *buffer,
132 	struct iio_dev *indio_dev);
133 int iio_dma_buffer_read(struct iio_buffer *buffer, size_t n,
134 	char __user *user_buffer);
135 size_t iio_dma_buffer_data_available(struct iio_buffer *buffer);
136 int iio_dma_buffer_set_bytes_per_datum(struct iio_buffer *buffer, size_t bpd);
137 int iio_dma_buffer_set_length(struct iio_buffer *buffer, unsigned int length);
138 int iio_dma_buffer_request_update(struct iio_buffer *buffer);
139 
140 int iio_dma_buffer_init(struct iio_dma_buffer_queue *queue,
141 	struct device *dma_dev, const struct iio_dma_buffer_ops *ops);
142 void iio_dma_buffer_exit(struct iio_dma_buffer_queue *queue);
143 void iio_dma_buffer_release(struct iio_dma_buffer_queue *queue);
144 
145 #endif
146