1// SPDX-License-Identifier: GPL-2.0-only
  2#include <linux/slab.h>
  3#include <linux/kernel.h>
  4#include <linux/module.h>
  5#include <linux/device.h>
  6#include <linux/workqueue.h>
  7#include <linux/kfifo.h>
  8#include <linux/mutex.h>
  9#include <linux/iio/iio.h>
 10#include <linux/iio/buffer.h>
 11#include <linux/iio/kfifo_buf.h>
 12#include <linux/iio/buffer_impl.h>
 13#include <linux/sched.h>
 14#include <linux/poll.h>
 15
 16struct iio_kfifo {
 17	struct iio_buffer buffer;
 18	struct kfifo kf;
 19	struct mutex user_lock;
 20	int update_needed;
 21};
 22
 23#define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
 24
 25static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
 26			size_t bytes_per_datum, unsigned int length)
 27{
 28	if ((length == 0) || (bytes_per_datum == 0))
 29		return -EINVAL;
 30
 31	/*
 32	 * Make sure we don't overflow an unsigned int after kfifo rounds up to
 33	 * the next power of 2.
 34	 */
 35	if (roundup_pow_of_two(length) > UINT_MAX / bytes_per_datum)
 36		return -EINVAL;
 37
 38	return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
 39			     bytes_per_datum, GFP_KERNEL);
 40}
 41
 42static int iio_request_update_kfifo(struct iio_buffer *r)
 43{
 44	int ret = 0;
 45	struct iio_kfifo *buf = iio_to_kfifo(r);
 46
 47	mutex_lock(&buf->user_lock);
 48	if (buf->update_needed) {
 49		kfifo_free(&buf->kf);
 50		ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
 51				   buf->buffer.length);
 52		if (ret >= 0)
 53			buf->update_needed = false;
 54	} else {
 55		kfifo_reset_out(&buf->kf);
 56	}
 57	mutex_unlock(&buf->user_lock);
 58
 59	return ret;
 60}
 61
 62static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
 63{
 64	struct iio_kfifo *kf = iio_to_kfifo(r);
 65	kf->update_needed = true;
 66	return 0;
 67}
 68
 69static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
 70{
 71	if (r->bytes_per_datum != bpd) {
 72		r->bytes_per_datum = bpd;
 73		iio_mark_update_needed_kfifo(r);
 74	}
 75	return 0;
 76}
 77
 78static int iio_set_length_kfifo(struct iio_buffer *r, unsigned int length)
 79{
 80	/* Avoid an invalid state */
 81	if (length < 2)
 82		length = 2;
 83	if (r->length != length) {
 84		r->length = length;
 85		iio_mark_update_needed_kfifo(r);
 86	}
 87	return 0;
 88}
 89
 90static int iio_store_to_kfifo(struct iio_buffer *r,
 91			      const void *data)
 92{
 93	int ret;
 94	struct iio_kfifo *kf = iio_to_kfifo(r);
 95	ret = kfifo_in(&kf->kf, data, 1);
 96	if (ret != 1)
 97		return -EBUSY;
 98	return 0;
 99}
100
101static int iio_read_kfifo(struct iio_buffer *r, size_t n, char __user *buf)
102{
103	int ret, copied;
104	struct iio_kfifo *kf = iio_to_kfifo(r);
105
106	if (mutex_lock_interruptible(&kf->user_lock))
107		return -ERESTARTSYS;
108
109	if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
110		ret = -EINVAL;
111	else
112		ret = kfifo_to_user(&kf->kf, buf, n, &copied);
113	mutex_unlock(&kf->user_lock);
114	if (ret < 0)
115		return ret;
116
117	return copied;
118}
119
120static size_t iio_kfifo_buf_data_available(struct iio_buffer *r)
121{
122	struct iio_kfifo *kf = iio_to_kfifo(r);
123	size_t samples;
124
125	mutex_lock(&kf->user_lock);
126	samples = kfifo_len(&kf->kf);
127	mutex_unlock(&kf->user_lock);
128
129	return samples;
130}
131
132static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
133{
134	struct iio_kfifo *kf = iio_to_kfifo(buffer);
135
136	mutex_destroy(&kf->user_lock);
137	kfifo_free(&kf->kf);
138	kfree(kf);
139}
140
141static size_t iio_kfifo_buf_space_available(struct iio_buffer *r)
142{
143	struct iio_kfifo *kf = iio_to_kfifo(r);
144	size_t avail;
145
146	mutex_lock(&kf->user_lock);
147	avail = kfifo_avail(&kf->kf);
148	mutex_unlock(&kf->user_lock);
149
150	return avail;
151}
152
153static int iio_kfifo_remove_from(struct iio_buffer *r, void *data)
154{
155	int ret;
156	struct iio_kfifo *kf = iio_to_kfifo(r);
157
158	if (kfifo_size(&kf->kf) < 1)
159		return -EBUSY;
160
161	ret = kfifo_out(&kf->kf, data, 1);
162	if (ret != 1)
163		return -EBUSY;
164
165	wake_up_interruptible_poll(&r->pollq, EPOLLOUT | EPOLLWRNORM);
166
167	return 0;
168}
169
170static int iio_kfifo_write(struct iio_buffer *r, size_t n,
171	const char __user *buf)
172{
173	struct iio_kfifo *kf = iio_to_kfifo(r);
174	int ret, copied;
175
176	mutex_lock(&kf->user_lock);
177	if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
178		ret = -EINVAL;
179	else
180		ret = kfifo_from_user(&kf->kf, buf, n, &copied);
181	mutex_unlock(&kf->user_lock);
182	if (ret)
183		return ret;
184
185	return copied;
186}
187
188static const struct iio_buffer_access_funcs kfifo_access_funcs = {
189	.store_to = &iio_store_to_kfifo,
190	.read = &iio_read_kfifo,
191	.data_available = iio_kfifo_buf_data_available,
192	.remove_from = &iio_kfifo_remove_from,
193	.write = &iio_kfifo_write,
194	.space_available = &iio_kfifo_buf_space_available,
195	.request_update = &iio_request_update_kfifo,
196	.set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
197	.set_length = &iio_set_length_kfifo,
198	.release = &iio_kfifo_buffer_release,
199
200	.modes = INDIO_BUFFER_SOFTWARE | INDIO_BUFFER_TRIGGERED,
201};
202
203struct iio_buffer *iio_kfifo_allocate(void)
204{
205	struct iio_kfifo *kf;
206
207	kf = kzalloc(sizeof(*kf), GFP_KERNEL);
208	if (!kf)
209		return NULL;
210
211	kf->update_needed = true;
212	iio_buffer_init(&kf->buffer);
213	kf->buffer.access = &kfifo_access_funcs;
214	kf->buffer.length = 2;
215	mutex_init(&kf->user_lock);
216
217	return &kf->buffer;
218}
219EXPORT_SYMBOL(iio_kfifo_allocate);
220
221void iio_kfifo_free(struct iio_buffer *r)
222{
223	iio_buffer_put(r);
224}
225EXPORT_SYMBOL(iio_kfifo_free);
226
227static void devm_iio_kfifo_release(struct device *dev, void *res)
228{
229	iio_kfifo_free(*(struct iio_buffer **)res);
230}
231
232/**
233 * devm_iio_kfifo_allocate - Resource-managed iio_kfifo_allocate()
234 * @dev:		Device to allocate kfifo buffer for
235 *
236 * RETURNS:
237 * Pointer to allocated iio_buffer on success, NULL on failure.
238 */
239static struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
240{
241	struct iio_buffer **ptr, *r;
242
243	ptr = devres_alloc(devm_iio_kfifo_release, sizeof(*ptr), GFP_KERNEL);
244	if (!ptr)
245		return NULL;
246
247	r = iio_kfifo_allocate();
248	if (r) {
249		*ptr = r;
250		devres_add(dev, ptr);
251	} else {
252		devres_free(ptr);
253	}
254
255	return r;
256}
257
258/**
259 * devm_iio_kfifo_buffer_setup_ext - Allocate a kfifo buffer & attach it to an IIO device
260 * @dev: Device object to which to attach the life-time of this kfifo buffer
261 * @indio_dev: The device the buffer should be attached to
262 * @setup_ops: The setup_ops required to configure the HW part of the buffer (optional)
263 * @buffer_attrs: Extra sysfs buffer attributes for this IIO buffer
264 *
265 * This function allocates a kfifo buffer via devm_iio_kfifo_allocate() and
266 * attaches it to the IIO device via iio_device_attach_buffer().
267 * This is meant to be a bit of a short-hand/helper function as there are a few
268 * drivers that seem to do this.
269 */
270int devm_iio_kfifo_buffer_setup_ext(struct device *dev,
271				    struct iio_dev *indio_dev,
272				    const struct iio_buffer_setup_ops *setup_ops,
273				    const struct iio_dev_attr **buffer_attrs)
274{
275	struct iio_buffer *buffer;
276
277	buffer = devm_iio_kfifo_allocate(dev);
278	if (!buffer)
279		return -ENOMEM;
280
281	indio_dev->modes |= INDIO_BUFFER_SOFTWARE;
282	indio_dev->setup_ops = setup_ops;
283
284	buffer->attrs = buffer_attrs;
285
286	return iio_device_attach_buffer(indio_dev, buffer);
287}
288EXPORT_SYMBOL_GPL(devm_iio_kfifo_buffer_setup_ext);
289
290MODULE_DESCRIPTION("Industrial I/O buffering based on kfifo");
291MODULE_LICENSE("GPL");