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/kfifo_buf.h>
  9#include <linux/sched.h>
 10#include <linux/poll.h>
 11
 12struct iio_kfifo {
 13	struct iio_buffer buffer;
 14	struct kfifo kf;
 15	struct mutex user_lock;
 16	int update_needed;
 17};
 18
 19#define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
 20
 21static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
 22				int bytes_per_datum, int length)
 23{
 24	if ((length == 0) || (bytes_per_datum == 0))
 25		return -EINVAL;
 26
 27	return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
 28			     bytes_per_datum, GFP_KERNEL);
 29}
 30
 31static int iio_request_update_kfifo(struct iio_buffer *r)
 32{
 33	int ret = 0;
 34	struct iio_kfifo *buf = iio_to_kfifo(r);
 35
 36	mutex_lock(&buf->user_lock);
 37	if (buf->update_needed) {
 38		kfifo_free(&buf->kf);
 39		ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
 40				   buf->buffer.length);
 41		if (ret >= 0)
 42			buf->update_needed = false;
 43	} else {
 44		kfifo_reset_out(&buf->kf);
 45	}
 46	mutex_unlock(&buf->user_lock);
 47
 48	return ret;
 49}
 50
 51static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
 52{
 53	struct iio_kfifo *kf = iio_to_kfifo(r);
 54	kf->update_needed = true;
 55	return 0;
 56}
 57
 58static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
 59{
 60	if (r->bytes_per_datum != bpd) {
 61		r->bytes_per_datum = bpd;
 62		iio_mark_update_needed_kfifo(r);
 63	}
 64	return 0;
 65}
 66
 67static int iio_set_length_kfifo(struct iio_buffer *r, int length)
 68{
 69	/* Avoid an invalid state */
 70	if (length < 2)
 71		length = 2;
 72	if (r->length != length) {
 73		r->length = length;
 74		iio_mark_update_needed_kfifo(r);
 75	}
 76	return 0;
 77}
 78
 79static int iio_store_to_kfifo(struct iio_buffer *r,
 80			      const void *data)
 81{
 82	int ret;
 83	struct iio_kfifo *kf = iio_to_kfifo(r);
 84	ret = kfifo_in(&kf->kf, data, 1);
 85	if (ret != 1)
 86		return -EBUSY;
 87	return 0;
 88}
 89
 90static int iio_read_first_n_kfifo(struct iio_buffer *r,
 91			   size_t n, char __user *buf)
 92{
 93	int ret, copied;
 94	struct iio_kfifo *kf = iio_to_kfifo(r);
 95
 96	if (mutex_lock_interruptible(&kf->user_lock))
 97		return -ERESTARTSYS;
 98
 99	if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
100		ret = -EINVAL;
101	else
102		ret = kfifo_to_user(&kf->kf, buf, n, &copied);
103	mutex_unlock(&kf->user_lock);
104	if (ret < 0)
105		return ret;
106
107	return copied;
108}
109
110static size_t iio_kfifo_buf_data_available(struct iio_buffer *r)
111{
112	struct iio_kfifo *kf = iio_to_kfifo(r);
113	size_t samples;
114
115	mutex_lock(&kf->user_lock);
116	samples = kfifo_len(&kf->kf);
117	mutex_unlock(&kf->user_lock);
118
119	return samples;
120}
121
122static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
123{
124	struct iio_kfifo *kf = iio_to_kfifo(buffer);
125
126	mutex_destroy(&kf->user_lock);
127	kfifo_free(&kf->kf);
128	kfree(kf);
129}
130
131static const struct iio_buffer_access_funcs kfifo_access_funcs = {
132	.store_to = &iio_store_to_kfifo,
133	.read_first_n = &iio_read_first_n_kfifo,
134	.data_available = iio_kfifo_buf_data_available,
135	.request_update = &iio_request_update_kfifo,
136	.set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
137	.set_length = &iio_set_length_kfifo,
138	.release = &iio_kfifo_buffer_release,
139
140	.modes = INDIO_BUFFER_SOFTWARE | INDIO_BUFFER_TRIGGERED,
141};
142
143struct iio_buffer *iio_kfifo_allocate(void)
144{
145	struct iio_kfifo *kf;
146
147	kf = kzalloc(sizeof(*kf), GFP_KERNEL);
148	if (!kf)
149		return NULL;
150
151	kf->update_needed = true;
152	iio_buffer_init(&kf->buffer);
153	kf->buffer.access = &kfifo_access_funcs;
154	kf->buffer.length = 2;
155	mutex_init(&kf->user_lock);
156
157	return &kf->buffer;
158}
159EXPORT_SYMBOL(iio_kfifo_allocate);
160
161void iio_kfifo_free(struct iio_buffer *r)
162{
163	iio_buffer_put(r);
164}
165EXPORT_SYMBOL(iio_kfifo_free);
166
167static void devm_iio_kfifo_release(struct device *dev, void *res)
168{
169	iio_kfifo_free(*(struct iio_buffer **)res);
170}
171
172static int devm_iio_kfifo_match(struct device *dev, void *res, void *data)
173{
174	struct iio_buffer **r = res;
175
176	if (WARN_ON(!r || !*r))
177		return 0;
178
179	return *r == data;
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
209/**
210 * devm_iio_fifo_free - Resource-managed iio_kfifo_free()
211 * @dev:		Device the buffer belongs to
212 * @r:			The buffer associated with the device
213 */
214void devm_iio_kfifo_free(struct device *dev, struct iio_buffer *r)
215{
216	WARN_ON(devres_release(dev, devm_iio_kfifo_release,
217			       devm_iio_kfifo_match, r));
218}
219EXPORT_SYMBOL(devm_iio_kfifo_free);
220
221MODULE_LICENSE("GPL");