1#include <linux/slab.h>
  2#include <linux/kernel.h>
  3#include <linux/module.h>
  4#include <linux/device.h>
  5#include <linux/workqueue.h>
  6#include <linux/kfifo.h>
  7#include <linux/mutex.h>
  8#include <linux/iio/iio.h>
  9#include <linux/iio/buffer.h>
 10#include <linux/iio/kfifo_buf.h>
 11#include <linux/iio/buffer_impl.h>
 12#include <linux/sched.h>
 13#include <linux/poll.h>
 14
 15struct iio_kfifo {
 16	struct iio_buffer buffer;
 17	struct kfifo kf;
 18	struct mutex user_lock;
 19	int update_needed;
 20};
 21
 22#define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
 23
 24static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
 25			size_t bytes_per_datum, unsigned int length)
 26{
 27	if ((length == 0) || (bytes_per_datum == 0))
 28		return -EINVAL;
 29
 30	/*
 31	 * Make sure we don't overflow an unsigned int after kfifo rounds up to
 32	 * the next power of 2.
 33	 */
 34	if (roundup_pow_of_two(length) > UINT_MAX / bytes_per_datum)
 35		return -EINVAL;
 36
 37	return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
 38			     bytes_per_datum, GFP_KERNEL);
 39}
 40
 41static int iio_request_update_kfifo(struct iio_buffer *r)
 42{
 43	int ret = 0;
 44	struct iio_kfifo *buf = iio_to_kfifo(r);
 45
 46	mutex_lock(&buf->user_lock);
 47	if (buf->update_needed) {
 48		kfifo_free(&buf->kf);
 49		ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
 50				   buf->buffer.length);
 51		if (ret >= 0)
 52			buf->update_needed = false;
 53	} else {
 54		kfifo_reset_out(&buf->kf);
 55	}
 56	mutex_unlock(&buf->user_lock);
 57
 58	return ret;
 59}
 60
 61static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
 62{
 63	struct iio_kfifo *kf = iio_to_kfifo(r);
 64	kf->update_needed = true;
 65	return 0;
 66}
 67
 68static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
 69{
 70	if (r->bytes_per_datum != bpd) {
 71		r->bytes_per_datum = bpd;
 72		iio_mark_update_needed_kfifo(r);
 73	}
 74	return 0;
 75}
 76
 77static int iio_set_length_kfifo(struct iio_buffer *r, unsigned int length)
 78{
 79	/* Avoid an invalid state */
 80	if (length < 2)
 81		length = 2;
 82	if (r->length != length) {
 83		r->length = length;
 84		iio_mark_update_needed_kfifo(r);
 85	}
 86	return 0;
 87}
 88
 89static int iio_store_to_kfifo(struct iio_buffer *r,
 90			      const void *data)
 91{
 92	int ret;
 93	struct iio_kfifo *kf = iio_to_kfifo(r);
 94	ret = kfifo_in(&kf->kf, data, 1);
 95	if (ret != 1)
 96		return -EBUSY;
 97	return 0;
 98}
 99
100static int iio_read_first_n_kfifo(struct iio_buffer *r,
101			   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_first_n = &iio_read_first_n_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
182static int devm_iio_kfifo_match(struct device *dev, void *res, void *data)
183{
184	struct iio_buffer **r = res;
185
186	if (WARN_ON(!r || !*r))
187		return 0;
188
189	return *r == data;
190}
191
192/**
193 * devm_iio_fifo_allocate - Resource-managed iio_kfifo_allocate()
194 * @dev:		Device to allocate kfifo buffer for
195 *
196 * RETURNS:
197 * Pointer to allocated iio_buffer on success, NULL on failure.
198 */
199struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
200{
201	struct iio_buffer **ptr, *r;
202
203	ptr = devres_alloc(devm_iio_kfifo_release, sizeof(*ptr), GFP_KERNEL);
204	if (!ptr)
205		return NULL;
206
207	r = iio_kfifo_allocate();
208	if (r) {
209		*ptr = r;
210		devres_add(dev, ptr);
211	} else {
212		devres_free(ptr);
213	}
214
215	return r;
216}
217EXPORT_SYMBOL(devm_iio_kfifo_allocate);
218
219/**
220 * devm_iio_fifo_free - Resource-managed iio_kfifo_free()
221 * @dev:		Device the buffer belongs to
222 * @r:			The buffer associated with the device
223 */
224void devm_iio_kfifo_free(struct device *dev, struct iio_buffer *r)
225{
226	WARN_ON(devres_release(dev, devm_iio_kfifo_release,
227			       devm_iio_kfifo_match, r));
228}
229EXPORT_SYMBOL(devm_iio_kfifo_free);
230
231MODULE_LICENSE("GPL");