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
16 struct 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
__iio_allocate_kfifo(struct iio_kfifo * buf,size_t bytes_per_datum,unsigned int length)25 static 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
iio_request_update_kfifo(struct iio_buffer * r)42 static 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
iio_mark_update_needed_kfifo(struct iio_buffer * r)62 static 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
iio_set_bytes_per_datum_kfifo(struct iio_buffer * r,size_t bpd)69 static 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
iio_set_length_kfifo(struct iio_buffer * r,unsigned int length)78 static 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
iio_store_to_kfifo(struct iio_buffer * r,const void * data)90 static 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
iio_read_kfifo(struct iio_buffer * r,size_t n,char __user * buf)101 static 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
iio_kfifo_buf_data_available(struct iio_buffer * r)120 static 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
iio_kfifo_buffer_release(struct iio_buffer * buffer)132 static 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
141 static 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
iio_kfifo_allocate(void)153 struct 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 }
169 EXPORT_SYMBOL(iio_kfifo_allocate);
170
iio_kfifo_free(struct iio_buffer * r)171 void iio_kfifo_free(struct iio_buffer *r)
172 {
173 iio_buffer_put(r);
174 }
175 EXPORT_SYMBOL(iio_kfifo_free);
176
devm_iio_kfifo_release(struct device * dev,void * res)177 static 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 */
devm_iio_kfifo_allocate(struct device * dev)189 struct 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 }
207 EXPORT_SYMBOL(devm_iio_kfifo_allocate);
208
209 MODULE_LICENSE("GPL");
210