1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright 2014-2015 Analog Devices Inc.
4 *  Author: Lars-Peter Clausen <lars@metafoo.de>
5 */
6
7#include <linux/slab.h>
8#include <linux/kernel.h>
9#include <linux/dmaengine.h>
10#include <linux/dma-mapping.h>
11#include <linux/spinlock.h>
12#include <linux/err.h>
13#include <linux/module.h>
14
15#include <linux/iio/iio.h>
16#include <linux/iio/sysfs.h>
17#include <linux/iio/buffer.h>
18#include <linux/iio/buffer_impl.h>
19#include <linux/iio/buffer-dma.h>
20#include <linux/iio/buffer-dmaengine.h>
21
22/*
23 * The IIO DMAengine buffer combines the generic IIO DMA buffer infrastructure
24 * with the DMAengine framework. The generic IIO DMA buffer infrastructure is
25 * used to manage the buffer memory and implement the IIO buffer operations
26 * while the DMAengine framework is used to perform the DMA transfers. Combined
27 * this results in a device independent fully functional DMA buffer
28 * implementation that can be used by device drivers for peripherals which are
29 * connected to a DMA controller which has a DMAengine driver implementation.
30 */
31
32struct dmaengine_buffer {
33	struct iio_dma_buffer_queue queue;
34
35	struct dma_chan *chan;
36	struct list_head active;
37
38	size_t align;
39	size_t max_size;
40};
41
42static struct dmaengine_buffer *iio_buffer_to_dmaengine_buffer(
43		struct iio_buffer *buffer)
44{
45	return container_of(buffer, struct dmaengine_buffer, queue.buffer);
46}
47
48static void iio_dmaengine_buffer_block_done(void *data,
49		const struct dmaengine_result *result)
50{
51	struct iio_dma_buffer_block *block = data;
52	unsigned long flags;
53
54	spin_lock_irqsave(&block->queue->list_lock, flags);
55	list_del(&block->head);
56	spin_unlock_irqrestore(&block->queue->list_lock, flags);
57	block->bytes_used -= result->residue;
58	iio_dma_buffer_block_done(block);
59}
60
61static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue,
62	struct iio_dma_buffer_block *block)
63{
64	struct dmaengine_buffer *dmaengine_buffer =
65		iio_buffer_to_dmaengine_buffer(&queue->buffer);
66	struct dma_async_tx_descriptor *desc;
67	dma_cookie_t cookie;
68
69	block->bytes_used = min(block->size, dmaengine_buffer->max_size);
70	block->bytes_used = rounddown(block->bytes_used,
71			dmaengine_buffer->align);
72
73	desc = dmaengine_prep_slave_single(dmaengine_buffer->chan,
74		block->phys_addr, block->bytes_used, DMA_DEV_TO_MEM,
75		DMA_PREP_INTERRUPT);
76	if (!desc)
77		return -ENOMEM;
78
79	desc->callback_result = iio_dmaengine_buffer_block_done;
80	desc->callback_param = block;
81
82	cookie = dmaengine_submit(desc);
83	if (dma_submit_error(cookie))
84		return dma_submit_error(cookie);
85
86	spin_lock_irq(&dmaengine_buffer->queue.list_lock);
87	list_add_tail(&block->head, &dmaengine_buffer->active);
88	spin_unlock_irq(&dmaengine_buffer->queue.list_lock);
89
90	dma_async_issue_pending(dmaengine_buffer->chan);
91
92	return 0;
93}
94
95static void iio_dmaengine_buffer_abort(struct iio_dma_buffer_queue *queue)
96{
97	struct dmaengine_buffer *dmaengine_buffer =
98		iio_buffer_to_dmaengine_buffer(&queue->buffer);
99
100	dmaengine_terminate_sync(dmaengine_buffer->chan);
101	iio_dma_buffer_block_list_abort(queue, &dmaengine_buffer->active);
102}
103
104static void iio_dmaengine_buffer_release(struct iio_buffer *buf)
105{
106	struct dmaengine_buffer *dmaengine_buffer =
107		iio_buffer_to_dmaengine_buffer(buf);
108
109	iio_dma_buffer_release(&dmaengine_buffer->queue);
110	kfree(dmaengine_buffer);
111}
112
113static const struct iio_buffer_access_funcs iio_dmaengine_buffer_ops = {
114	.read = iio_dma_buffer_read,
115	.set_bytes_per_datum = iio_dma_buffer_set_bytes_per_datum,
116	.set_length = iio_dma_buffer_set_length,
117	.request_update = iio_dma_buffer_request_update,
118	.enable = iio_dma_buffer_enable,
119	.disable = iio_dma_buffer_disable,
120	.data_available = iio_dma_buffer_data_available,
121	.release = iio_dmaengine_buffer_release,
122
123	.modes = INDIO_BUFFER_HARDWARE,
124	.flags = INDIO_BUFFER_FLAG_FIXED_WATERMARK,
125};
126
127static const struct iio_dma_buffer_ops iio_dmaengine_default_ops = {
128	.submit = iio_dmaengine_buffer_submit_block,
129	.abort = iio_dmaengine_buffer_abort,
130};
131
132static ssize_t iio_dmaengine_buffer_get_length_align(struct device *dev,
133	struct device_attribute *attr, char *buf)
134{
135	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
136	struct dmaengine_buffer *dmaengine_buffer =
137		iio_buffer_to_dmaengine_buffer(indio_dev->buffer);
138
139	return sprintf(buf, "%zu\n", dmaengine_buffer->align);
140}
141
142static IIO_DEVICE_ATTR(length_align_bytes, 0444,
143		       iio_dmaengine_buffer_get_length_align, NULL, 0);
144
145static const struct attribute *iio_dmaengine_buffer_attrs[] = {
146	&iio_dev_attr_length_align_bytes.dev_attr.attr,
147	NULL,
148};
149
150/**
151 * iio_dmaengine_buffer_alloc() - Allocate new buffer which uses DMAengine
152 * @dev: Parent device for the buffer
153 * @channel: DMA channel name, typically "rx".
154 *
155 * This allocates a new IIO buffer which internally uses the DMAengine framework
156 * to perform its transfers. The parent device will be used to request the DMA
157 * channel.
158 *
159 * Once done using the buffer iio_dmaengine_buffer_free() should be used to
160 * release it.
161 */
162static struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
163	const char *channel)
164{
165	struct dmaengine_buffer *dmaengine_buffer;
166	unsigned int width, src_width, dest_width;
167	struct dma_slave_caps caps;
168	struct dma_chan *chan;
169	int ret;
170
171	dmaengine_buffer = kzalloc(sizeof(*dmaengine_buffer), GFP_KERNEL);
172	if (!dmaengine_buffer)
173		return ERR_PTR(-ENOMEM);
174
175	chan = dma_request_chan(dev, channel);
176	if (IS_ERR(chan)) {
177		ret = PTR_ERR(chan);
178		goto err_free;
179	}
180
181	ret = dma_get_slave_caps(chan, &caps);
182	if (ret < 0)
183		goto err_free;
184
185	/* Needs to be aligned to the maximum of the minimums */
186	if (caps.src_addr_widths)
187		src_width = __ffs(caps.src_addr_widths);
188	else
189		src_width = 1;
190	if (caps.dst_addr_widths)
191		dest_width = __ffs(caps.dst_addr_widths);
192	else
193		dest_width = 1;
194	width = max(src_width, dest_width);
195
196	INIT_LIST_HEAD(&dmaengine_buffer->active);
197	dmaengine_buffer->chan = chan;
198	dmaengine_buffer->align = width;
199	dmaengine_buffer->max_size = dma_get_max_seg_size(chan->device->dev);
200
201	iio_dma_buffer_init(&dmaengine_buffer->queue, chan->device->dev,
202		&iio_dmaengine_default_ops);
203	iio_buffer_set_attrs(&dmaengine_buffer->queue.buffer,
204		iio_dmaengine_buffer_attrs);
205
206	dmaengine_buffer->queue.buffer.access = &iio_dmaengine_buffer_ops;
207
208	return &dmaengine_buffer->queue.buffer;
209
210err_free:
211	kfree(dmaengine_buffer);
212	return ERR_PTR(ret);
213}
214
215/**
216 * iio_dmaengine_buffer_free() - Free dmaengine buffer
217 * @buffer: Buffer to free
218 *
219 * Frees a buffer previously allocated with iio_dmaengine_buffer_alloc().
220 */
221static void iio_dmaengine_buffer_free(struct iio_buffer *buffer)
222{
223	struct dmaengine_buffer *dmaengine_buffer =
224		iio_buffer_to_dmaengine_buffer(buffer);
225
226	iio_dma_buffer_exit(&dmaengine_buffer->queue);
227	dma_release_channel(dmaengine_buffer->chan);
228
229	iio_buffer_put(buffer);
230}
231
232static void __devm_iio_dmaengine_buffer_free(struct device *dev, void *res)
233{
234	iio_dmaengine_buffer_free(*(struct iio_buffer **)res);
235}
236
237/**
238 * devm_iio_dmaengine_buffer_alloc() - Resource-managed iio_dmaengine_buffer_alloc()
239 * @dev: Parent device for the buffer
240 * @channel: DMA channel name, typically "rx".
241 *
242 * This allocates a new IIO buffer which internally uses the DMAengine framework
243 * to perform its transfers. The parent device will be used to request the DMA
244 * channel.
245 *
246 * The buffer will be automatically de-allocated once the device gets destroyed.
247 */
248struct iio_buffer *devm_iio_dmaengine_buffer_alloc(struct device *dev,
249	const char *channel)
250{
251	struct iio_buffer **bufferp, *buffer;
252
253	bufferp = devres_alloc(__devm_iio_dmaengine_buffer_free,
254			       sizeof(*bufferp), GFP_KERNEL);
255	if (!bufferp)
256		return ERR_PTR(-ENOMEM);
257
258	buffer = iio_dmaengine_buffer_alloc(dev, channel);
259	if (IS_ERR(buffer)) {
260		devres_free(bufferp);
261		return buffer;
262	}
263
264	*bufferp = buffer;
265	devres_add(dev, bufferp);
266
267	return buffer;
268}
269EXPORT_SYMBOL_GPL(devm_iio_dmaengine_buffer_alloc);
270
271MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
272MODULE_DESCRIPTION("DMA buffer for the IIO framework");
273MODULE_LICENSE("GPL");
274