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 
iio_kfifo_buf_space_available(struct iio_buffer * r)141 static size_t iio_kfifo_buf_space_available(struct iio_buffer *r)
142 {
143 	struct iio_kfifo *kf = iio_to_kfifo(r);
144 	size_t avail;
145 
146 	mutex_lock(&kf->user_lock);
147 	avail = kfifo_avail(&kf->kf);
148 	mutex_unlock(&kf->user_lock);
149 
150 	return avail;
151 }
152 
iio_kfifo_remove_from(struct iio_buffer * r,void * data)153 static int iio_kfifo_remove_from(struct iio_buffer *r, void *data)
154 {
155 	int ret;
156 	struct iio_kfifo *kf = iio_to_kfifo(r);
157 
158 	if (kfifo_size(&kf->kf) < 1)
159 		return -EBUSY;
160 
161 	ret = kfifo_out(&kf->kf, data, 1);
162 	if (ret != 1)
163 		return -EBUSY;
164 
165 	wake_up_interruptible_poll(&r->pollq, EPOLLOUT | EPOLLWRNORM);
166 
167 	return 0;
168 }
169 
iio_kfifo_write(struct iio_buffer * r,size_t n,const char __user * buf)170 static int iio_kfifo_write(struct iio_buffer *r, size_t n,
171 	const char __user *buf)
172 {
173 	struct iio_kfifo *kf = iio_to_kfifo(r);
174 	int ret, copied;
175 
176 	mutex_lock(&kf->user_lock);
177 	if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
178 		ret = -EINVAL;
179 	else
180 		ret = kfifo_from_user(&kf->kf, buf, n, &copied);
181 	mutex_unlock(&kf->user_lock);
182 	if (ret)
183 		return ret;
184 
185 	return copied;
186 }
187 
188 static const struct iio_buffer_access_funcs kfifo_access_funcs = {
189 	.store_to = &iio_store_to_kfifo,
190 	.read = &iio_read_kfifo,
191 	.data_available = iio_kfifo_buf_data_available,
192 	.remove_from = &iio_kfifo_remove_from,
193 	.write = &iio_kfifo_write,
194 	.space_available = &iio_kfifo_buf_space_available,
195 	.request_update = &iio_request_update_kfifo,
196 	.set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
197 	.set_length = &iio_set_length_kfifo,
198 	.release = &iio_kfifo_buffer_release,
199 
200 	.modes = INDIO_BUFFER_SOFTWARE | INDIO_BUFFER_TRIGGERED,
201 };
202 
iio_kfifo_allocate(void)203 struct iio_buffer *iio_kfifo_allocate(void)
204 {
205 	struct iio_kfifo *kf;
206 
207 	kf = kzalloc(sizeof(*kf), GFP_KERNEL);
208 	if (!kf)
209 		return NULL;
210 
211 	kf->update_needed = true;
212 	iio_buffer_init(&kf->buffer);
213 	kf->buffer.access = &kfifo_access_funcs;
214 	kf->buffer.length = 2;
215 	mutex_init(&kf->user_lock);
216 
217 	return &kf->buffer;
218 }
219 EXPORT_SYMBOL(iio_kfifo_allocate);
220 
iio_kfifo_free(struct iio_buffer * r)221 void iio_kfifo_free(struct iio_buffer *r)
222 {
223 	iio_buffer_put(r);
224 }
225 EXPORT_SYMBOL(iio_kfifo_free);
226 
devm_iio_kfifo_release(struct device * dev,void * res)227 static void devm_iio_kfifo_release(struct device *dev, void *res)
228 {
229 	iio_kfifo_free(*(struct iio_buffer **)res);
230 }
231 
232 /**
233  * devm_iio_kfifo_allocate - Resource-managed iio_kfifo_allocate()
234  * @dev:		Device to allocate kfifo buffer for
235  *
236  * RETURNS:
237  * Pointer to allocated iio_buffer on success, NULL on failure.
238  */
devm_iio_kfifo_allocate(struct device * dev)239 static struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
240 {
241 	struct iio_buffer **ptr, *r;
242 
243 	ptr = devres_alloc(devm_iio_kfifo_release, sizeof(*ptr), GFP_KERNEL);
244 	if (!ptr)
245 		return NULL;
246 
247 	r = iio_kfifo_allocate();
248 	if (r) {
249 		*ptr = r;
250 		devres_add(dev, ptr);
251 	} else {
252 		devres_free(ptr);
253 	}
254 
255 	return r;
256 }
257 
258 /**
259  * devm_iio_kfifo_buffer_setup_ext - Allocate a kfifo buffer & attach it to an IIO device
260  * @dev: Device object to which to attach the life-time of this kfifo buffer
261  * @indio_dev: The device the buffer should be attached to
262  * @setup_ops: The setup_ops required to configure the HW part of the buffer (optional)
263  * @buffer_attrs: Extra sysfs buffer attributes for this IIO buffer
264  *
265  * This function allocates a kfifo buffer via devm_iio_kfifo_allocate() and
266  * attaches it to the IIO device via iio_device_attach_buffer().
267  * This is meant to be a bit of a short-hand/helper function as there are a few
268  * drivers that seem to do this.
269  */
devm_iio_kfifo_buffer_setup_ext(struct device * dev,struct iio_dev * indio_dev,const struct iio_buffer_setup_ops * setup_ops,const struct iio_dev_attr ** buffer_attrs)270 int devm_iio_kfifo_buffer_setup_ext(struct device *dev,
271 				    struct iio_dev *indio_dev,
272 				    const struct iio_buffer_setup_ops *setup_ops,
273 				    const struct iio_dev_attr **buffer_attrs)
274 {
275 	struct iio_buffer *buffer;
276 
277 	buffer = devm_iio_kfifo_allocate(dev);
278 	if (!buffer)
279 		return -ENOMEM;
280 
281 	indio_dev->modes |= INDIO_BUFFER_SOFTWARE;
282 	indio_dev->setup_ops = setup_ops;
283 
284 	buffer->attrs = buffer_attrs;
285 
286 	return iio_device_attach_buffer(indio_dev, buffer);
287 }
288 EXPORT_SYMBOL_GPL(devm_iio_kfifo_buffer_setup_ext);
289 
290 MODULE_LICENSE("GPL");
291