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 const struct iio_buffer_access_funcs kfifo_access_funcs = {
142	.store_to = &iio_store_to_kfifo,
143	.read = &iio_read_kfifo,
144	.data_available = iio_kfifo_buf_data_available,
145	.request_update = &iio_request_update_kfifo,
146	.set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
147	.set_length = &iio_set_length_kfifo,
148	.release = &iio_kfifo_buffer_release,
149
150	.modes = INDIO_BUFFER_SOFTWARE | INDIO_BUFFER_TRIGGERED,
151};
152
153struct iio_buffer *iio_kfifo_allocate(void)
154{
155	struct iio_kfifo *kf;
156
157	kf = kzalloc(sizeof(*kf), GFP_KERNEL);
158	if (!kf)
159		return NULL;
160
161	kf->update_needed = true;
162	iio_buffer_init(&kf->buffer);
163	kf->buffer.access = &kfifo_access_funcs;
164	kf->buffer.length = 2;
165	mutex_init(&kf->user_lock);
166
167	return &kf->buffer;
168}
169EXPORT_SYMBOL(iio_kfifo_allocate);
170
171void iio_kfifo_free(struct iio_buffer *r)
172{
173	iio_buffer_put(r);
174}
175EXPORT_SYMBOL(iio_kfifo_free);
176
177static void devm_iio_kfifo_release(struct device *dev, void *res)
178{
179	iio_kfifo_free(*(struct iio_buffer **)res);
180}
181
182/**
183 * devm_iio_fifo_allocate - Resource-managed iio_kfifo_allocate()
184 * @dev:		Device to allocate kfifo buffer for
185 *
186 * RETURNS:
187 * Pointer to allocated iio_buffer on success, NULL on failure.
188 */
189struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
190{
191	struct iio_buffer **ptr, *r;
192
193	ptr = devres_alloc(devm_iio_kfifo_release, sizeof(*ptr), GFP_KERNEL);
194	if (!ptr)
195		return NULL;
196
197	r = iio_kfifo_allocate();
198	if (r) {
199		*ptr = r;
200		devres_add(dev, ptr);
201	} else {
202		devres_free(ptr);
203	}
204
205	return r;
206}
207EXPORT_SYMBOL(devm_iio_kfifo_allocate);
208
209MODULE_LICENSE("GPL");