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_first_n_kfifo(struct iio_buffer *r,
102			   size_t n, char __user *buf)
103{
104	int ret, copied;
105	struct iio_kfifo *kf = iio_to_kfifo(r);
106
107	if (mutex_lock_interruptible(&kf->user_lock))
108		return -ERESTARTSYS;
109
110	if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
111		ret = -EINVAL;
112	else
113		ret = kfifo_to_user(&kf->kf, buf, n, &copied);
114	mutex_unlock(&kf->user_lock);
115	if (ret < 0)
116		return ret;
117
118	return copied;
119}
120
121static size_t iio_kfifo_buf_data_available(struct iio_buffer *r)
122{
123	struct iio_kfifo *kf = iio_to_kfifo(r);
124	size_t samples;
125
126	mutex_lock(&kf->user_lock);
127	samples = kfifo_len(&kf->kf);
128	mutex_unlock(&kf->user_lock);
129
130	return samples;
131}
132
133static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
134{
135	struct iio_kfifo *kf = iio_to_kfifo(buffer);
136
137	mutex_destroy(&kf->user_lock);
138	kfifo_free(&kf->kf);
139	kfree(kf);
140}
141
142static const struct iio_buffer_access_funcs kfifo_access_funcs = {
143	.store_to = &iio_store_to_kfifo,
144	.read_first_n = &iio_read_first_n_kfifo,
145	.data_available = iio_kfifo_buf_data_available,
146	.request_update = &iio_request_update_kfifo,
147	.set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
148	.set_length = &iio_set_length_kfifo,
149	.release = &iio_kfifo_buffer_release,
150
151	.modes = INDIO_BUFFER_SOFTWARE | INDIO_BUFFER_TRIGGERED,
152};
153
154struct iio_buffer *iio_kfifo_allocate(void)
155{
156	struct iio_kfifo *kf;
157
158	kf = kzalloc(sizeof(*kf), GFP_KERNEL);
159	if (!kf)
160		return NULL;
161
162	kf->update_needed = true;
163	iio_buffer_init(&kf->buffer);
164	kf->buffer.access = &kfifo_access_funcs;
165	kf->buffer.length = 2;
166	mutex_init(&kf->user_lock);
167
168	return &kf->buffer;
169}
170EXPORT_SYMBOL(iio_kfifo_allocate);
171
172void iio_kfifo_free(struct iio_buffer *r)
173{
174	iio_buffer_put(r);
175}
176EXPORT_SYMBOL(iio_kfifo_free);
177
178static void devm_iio_kfifo_release(struct device *dev, void *res)
179{
180	iio_kfifo_free(*(struct iio_buffer **)res);
181}
182
183static int devm_iio_kfifo_match(struct device *dev, void *res, void *data)
184{
185	struct iio_buffer **r = res;
186
187	if (WARN_ON(!r || !*r))
188		return 0;
189
190	return *r == data;
191}
192
193/**
194 * devm_iio_fifo_allocate - Resource-managed iio_kfifo_allocate()
195 * @dev:		Device to allocate kfifo buffer for
196 *
197 * RETURNS:
198 * Pointer to allocated iio_buffer on success, NULL on failure.
199 */
200struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
201{
202	struct iio_buffer **ptr, *r;
203
204	ptr = devres_alloc(devm_iio_kfifo_release, sizeof(*ptr), GFP_KERNEL);
205	if (!ptr)
206		return NULL;
207
208	r = iio_kfifo_allocate();
209	if (r) {
210		*ptr = r;
211		devres_add(dev, ptr);
212	} else {
213		devres_free(ptr);
214	}
215
216	return r;
217}
218EXPORT_SYMBOL(devm_iio_kfifo_allocate);
219
220/**
221 * devm_iio_fifo_free - Resource-managed iio_kfifo_free()
222 * @dev:		Device the buffer belongs to
223 * @r:			The buffer associated with the device
224 */
225void devm_iio_kfifo_free(struct device *dev, struct iio_buffer *r)
226{
227	WARN_ON(devres_release(dev, devm_iio_kfifo_release,
228			       devm_iio_kfifo_match, r));
229}
230EXPORT_SYMBOL(devm_iio_kfifo_free);
231
232MODULE_LICENSE("GPL");