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
141struct iio_buffer *iio_kfifo_allocate(void)
142{
143	struct iio_kfifo *kf;
144
145	kf = kzalloc(sizeof(*kf), GFP_KERNEL);
146	if (!kf)
147		return NULL;
148
149	kf->update_needed = true;
150	iio_buffer_init(&kf->buffer);
151	kf->buffer.access = &kfifo_access_funcs;
152	kf->buffer.length = 2;
153	mutex_init(&kf->user_lock);
154
155	return &kf->buffer;
156}
157EXPORT_SYMBOL(iio_kfifo_allocate);
158
159void iio_kfifo_free(struct iio_buffer *r)
160{
161	iio_buffer_put(r);
162}
163EXPORT_SYMBOL(iio_kfifo_free);
164
165static void devm_iio_kfifo_release(struct device *dev, void *res)
166{
167	iio_kfifo_free(*(struct iio_buffer **)res);
168}
169
170static int devm_iio_kfifo_match(struct device *dev, void *res, void *data)
171{
172	struct iio_buffer **r = res;
173
174	if (WARN_ON(!r || !*r))
175		return 0;
176
177	return *r == data;
178}
179
180/**
181 * devm_iio_fifo_allocate - Resource-managed iio_kfifo_allocate()
182 * @dev:		Device to allocate kfifo buffer for
183 *
184 * RETURNS:
185 * Pointer to allocated iio_buffer on success, NULL on failure.
186 */
187struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
188{
189	struct iio_buffer **ptr, *r;
190
191	ptr = devres_alloc(devm_iio_kfifo_release, sizeof(*ptr), GFP_KERNEL);
192	if (!ptr)
193		return NULL;
194
195	r = iio_kfifo_allocate();
196	if (r) {
197		*ptr = r;
198		devres_add(dev, ptr);
199	} else {
200		devres_free(ptr);
201	}
202
203	return r;
204}
205EXPORT_SYMBOL(devm_iio_kfifo_allocate);
206
207/**
208 * devm_iio_fifo_free - Resource-managed iio_kfifo_free()
209 * @dev:		Device the buffer belongs to
210 * @r:			The buffer associated with the device
211 */
212void devm_iio_kfifo_free(struct device *dev, struct iio_buffer *r)
213{
214	WARN_ON(devres_release(dev, devm_iio_kfifo_release,
215			       devm_iio_kfifo_match, r));
216}
217EXPORT_SYMBOL(devm_iio_kfifo_free);
218
219MODULE_LICENSE("GPL");
220