xref: /linux/drivers/iio/proximity/as3935.c (revision 3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d) 
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * as3935.c - Support for AS3935 Franklin lightning sensor
4  *
5  * Copyright (C) 2014, 2017-2018
6  * Author: Matt Ranostay <matt.ranostay@konsulko.com>
7  */
8 
9 #include <linux/module.h>
10 #include <linux/init.h>
11 #include <linux/interrupt.h>
12 #include <linux/delay.h>
13 #include <linux/workqueue.h>
14 #include <linux/devm-helpers.h>
15 #include <linux/mutex.h>
16 #include <linux/err.h>
17 #include <linux/irq.h>
18 #include <linux/spi/spi.h>
19 #include <linux/iio/iio.h>
20 #include <linux/iio/sysfs.h>
21 #include <linux/iio/trigger.h>
22 #include <linux/iio/trigger_consumer.h>
23 #include <linux/iio/buffer.h>
24 #include <linux/iio/triggered_buffer.h>
25 
26 #define AS3935_AFE_GAIN		0x00
27 #define AS3935_AFE_MASK		0x3F
28 #define AS3935_AFE_GAIN_MAX	0x1F
29 #define AS3935_AFE_PWR_BIT	BIT(0)
30 
31 #define AS3935_NFLWDTH		0x01
32 #define AS3935_NFLWDTH_MASK	0x7f
33 
34 #define AS3935_INT		0x03
35 #define AS3935_INT_MASK		0x0f
36 #define AS3935_DISTURB_INT	BIT(2)
37 #define AS3935_EVENT_INT	BIT(3)
38 #define AS3935_NOISE_INT	BIT(0)
39 
40 #define AS3935_DATA		0x07
41 #define AS3935_DATA_MASK	0x3F
42 
43 #define AS3935_TUNE_CAP		0x08
44 #define AS3935_DEFAULTS		0x3C
45 #define AS3935_CALIBRATE	0x3D
46 
47 #define AS3935_READ_DATA	BIT(14)
48 #define AS3935_ADDRESS(x)	((x) << 8)
49 
50 #define MAX_PF_CAP		120
51 #define TUNE_CAP_DIV		8
52 
53 struct as3935_state {
54 	struct spi_device *spi;
55 	struct iio_trigger *trig;
56 	struct mutex lock;
57 	struct delayed_work work;
58 
59 	unsigned long noise_tripped;
60 	u32 tune_cap;
61 	u32 nflwdth_reg;
62 	/* Ensure timestamp is naturally aligned */
63 	struct {
64 		u8 chan;
65 		aligned_s64 timestamp;
66 	} scan;
67 	u8 buf[2] __aligned(IIO_DMA_MINALIGN);
68 };
69 
70 static const struct iio_chan_spec as3935_channels[] = {
71 	{
72 		.type           = IIO_PROXIMITY,
73 		.info_mask_separate =
74 			BIT(IIO_CHAN_INFO_RAW) |
75 			BIT(IIO_CHAN_INFO_PROCESSED) |
76 			BIT(IIO_CHAN_INFO_SCALE),
77 		.scan_index     = 0,
78 		.scan_type = {
79 			.sign           = 'u',
80 			.realbits       = 6,
81 			.storagebits    = 8,
82 		},
83 	},
84 	IIO_CHAN_SOFT_TIMESTAMP(1),
85 };
86 
87 static int as3935_read(struct as3935_state *st, unsigned int reg, int *val)
88 {
89 	u8 cmd;
90 	int ret;
91 
92 	cmd = (AS3935_READ_DATA | AS3935_ADDRESS(reg)) >> 8;
93 	ret = spi_w8r8(st->spi, cmd);
94 	if (ret < 0)
95 		return ret;
96 	*val = ret;
97 
98 	return 0;
99 }
100 
101 static int as3935_write(struct as3935_state *st,
102 				unsigned int reg,
103 				unsigned int val)
104 {
105 	u8 *buf = st->buf;
106 
107 	buf[0] = AS3935_ADDRESS(reg) >> 8;
108 	buf[1] = val;
109 
110 	return spi_write(st->spi, buf, 2);
111 }
112 
113 static ssize_t as3935_sensor_sensitivity_show(struct device *dev,
114 					struct device_attribute *attr,
115 					char *buf)
116 {
117 	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
118 	int val, ret;
119 
120 	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
121 	if (ret)
122 		return ret;
123 	val = (val & AS3935_AFE_MASK) >> 1;
124 
125 	return sysfs_emit(buf, "%d\n", val);
126 }
127 
128 static ssize_t as3935_sensor_sensitivity_store(struct device *dev,
129 					struct device_attribute *attr,
130 					const char *buf, size_t len)
131 {
132 	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
133 	unsigned long val;
134 	int ret;
135 
136 	ret = kstrtoul(buf, 10, &val);
137 	if (ret)
138 		return -EINVAL;
139 
140 	if (val > AS3935_AFE_GAIN_MAX)
141 		return -EINVAL;
142 
143 	as3935_write(st, AS3935_AFE_GAIN, val << 1);
144 
145 	return len;
146 }
147 
148 static ssize_t as3935_noise_level_tripped_show(struct device *dev,
149 					struct device_attribute *attr,
150 					char *buf)
151 {
152 	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
153 	int ret;
154 
155 	mutex_lock(&st->lock);
156 	ret = sysfs_emit(buf, "%d\n", !time_after(jiffies, st->noise_tripped + HZ));
157 	mutex_unlock(&st->lock);
158 
159 	return ret;
160 }
161 
162 static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
163 	as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0);
164 
165 static IIO_DEVICE_ATTR(noise_level_tripped, S_IRUGO,
166 	as3935_noise_level_tripped_show, NULL, 0);
167 
168 static struct attribute *as3935_attributes[] = {
169 	&iio_dev_attr_sensor_sensitivity.dev_attr.attr,
170 	&iio_dev_attr_noise_level_tripped.dev_attr.attr,
171 	NULL,
172 };
173 
174 static const struct attribute_group as3935_attribute_group = {
175 	.attrs = as3935_attributes,
176 };
177 
178 static int as3935_read_raw(struct iio_dev *indio_dev,
179 			   struct iio_chan_spec const *chan,
180 			   int *val,
181 			   int *val2,
182 			   long m)
183 {
184 	struct as3935_state *st = iio_priv(indio_dev);
185 	int ret;
186 
187 
188 	switch (m) {
189 	case IIO_CHAN_INFO_PROCESSED:
190 	case IIO_CHAN_INFO_RAW:
191 		*val2 = 0;
192 		ret = as3935_read(st, AS3935_DATA, val);
193 		if (ret)
194 			return ret;
195 
196 		/* storm out of range */
197 		if (*val == AS3935_DATA_MASK)
198 			return -EINVAL;
199 
200 		if (m == IIO_CHAN_INFO_RAW)
201 			return IIO_VAL_INT;
202 
203 		if (m == IIO_CHAN_INFO_PROCESSED)
204 			*val *= 1000;
205 		break;
206 	case IIO_CHAN_INFO_SCALE:
207 		*val = 1000;
208 		break;
209 	default:
210 		return -EINVAL;
211 	}
212 
213 	return IIO_VAL_INT;
214 }
215 
216 static const struct iio_info as3935_info = {
217 	.attrs = &as3935_attribute_group,
218 	.read_raw = &as3935_read_raw,
219 };
220 
221 static irqreturn_t as3935_trigger_handler(int irq, void *private)
222 {
223 	struct iio_poll_func *pf = private;
224 	struct iio_dev *indio_dev = pf->indio_dev;
225 	struct as3935_state *st = iio_priv(indio_dev);
226 	int val, ret;
227 
228 	ret = as3935_read(st, AS3935_DATA, &val);
229 	if (ret)
230 		goto err_read;
231 
232 	st->scan.chan = val & AS3935_DATA_MASK;
233 	iio_push_to_buffers_with_ts(indio_dev, &st->scan, sizeof(st->scan),
234 				    iio_get_time_ns(indio_dev));
235 err_read:
236 	iio_trigger_notify_done(indio_dev->trig);
237 
238 	return IRQ_HANDLED;
239 }
240 
241 static void as3935_event_work(struct work_struct *work)
242 {
243 	struct as3935_state *st;
244 	int val;
245 	int ret;
246 
247 	st = container_of(work, struct as3935_state, work.work);
248 
249 	ret = as3935_read(st, AS3935_INT, &val);
250 	if (ret) {
251 		dev_warn(&st->spi->dev, "read error\n");
252 		return;
253 	}
254 
255 	val &= AS3935_INT_MASK;
256 
257 	switch (val) {
258 	case AS3935_EVENT_INT:
259 		iio_trigger_poll_nested(st->trig);
260 		break;
261 	case AS3935_DISTURB_INT:
262 	case AS3935_NOISE_INT:
263 		mutex_lock(&st->lock);
264 		st->noise_tripped = jiffies;
265 		mutex_unlock(&st->lock);
266 		dev_warn(&st->spi->dev, "noise level is too high\n");
267 		break;
268 	}
269 }
270 
271 static irqreturn_t as3935_interrupt_handler(int irq, void *private)
272 {
273 	struct iio_dev *indio_dev = private;
274 	struct as3935_state *st = iio_priv(indio_dev);
275 
276 	/*
277 	 * Delay work for >2 milliseconds after an interrupt to allow
278 	 * estimated distance to recalculated.
279 	 */
280 
281 	schedule_delayed_work(&st->work, msecs_to_jiffies(3));
282 
283 	return IRQ_HANDLED;
284 }
285 
286 static void calibrate_as3935(struct as3935_state *st)
287 {
288 	as3935_write(st, AS3935_DEFAULTS, 0x96);
289 	as3935_write(st, AS3935_CALIBRATE, 0x96);
290 	as3935_write(st, AS3935_TUNE_CAP,
291 		BIT(5) | (st->tune_cap / TUNE_CAP_DIV));
292 
293 	mdelay(2);
294 	as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV));
295 	as3935_write(st, AS3935_NFLWDTH, st->nflwdth_reg);
296 }
297 
298 static int as3935_suspend(struct device *dev)
299 {
300 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
301 	struct as3935_state *st = iio_priv(indio_dev);
302 	int val, ret;
303 
304 	mutex_lock(&st->lock);
305 	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
306 	if (ret)
307 		goto err_suspend;
308 	val |= AS3935_AFE_PWR_BIT;
309 
310 	ret = as3935_write(st, AS3935_AFE_GAIN, val);
311 
312 err_suspend:
313 	mutex_unlock(&st->lock);
314 
315 	return ret;
316 }
317 
318 static int as3935_resume(struct device *dev)
319 {
320 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
321 	struct as3935_state *st = iio_priv(indio_dev);
322 	int val, ret;
323 
324 	mutex_lock(&st->lock);
325 	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
326 	if (ret)
327 		goto err_resume;
328 	val &= ~AS3935_AFE_PWR_BIT;
329 	ret = as3935_write(st, AS3935_AFE_GAIN, val);
330 
331 	calibrate_as3935(st);
332 
333 err_resume:
334 	mutex_unlock(&st->lock);
335 
336 	return ret;
337 }
338 
339 static DEFINE_SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
340 
341 static int as3935_probe(struct spi_device *spi)
342 {
343 	struct device *dev = &spi->dev;
344 	struct iio_dev *indio_dev;
345 	struct iio_trigger *trig;
346 	struct as3935_state *st;
347 	int ret;
348 
349 	/* Be sure lightning event interrupt is specified */
350 	if (!spi->irq) {
351 		dev_err(dev, "unable to get event interrupt\n");
352 		return -EINVAL;
353 	}
354 
355 	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
356 	if (!indio_dev)
357 		return -ENOMEM;
358 
359 	st = iio_priv(indio_dev);
360 	st->spi = spi;
361 
362 	spi_set_drvdata(spi, indio_dev);
363 	mutex_init(&st->lock);
364 
365 	ret = device_property_read_u32(dev,
366 			"ams,tuning-capacitor-pf", &st->tune_cap);
367 	if (ret) {
368 		st->tune_cap = 0;
369 		dev_warn(dev, "no tuning-capacitor-pf set, defaulting to %d",
370 			st->tune_cap);
371 	}
372 
373 	if (st->tune_cap > MAX_PF_CAP) {
374 		dev_err(dev, "wrong tuning-capacitor-pf setting of %d\n",
375 			st->tune_cap);
376 		return -EINVAL;
377 	}
378 
379 	ret = device_property_read_u32(dev,
380 			"ams,nflwdth", &st->nflwdth_reg);
381 	if (!ret && st->nflwdth_reg > AS3935_NFLWDTH_MASK) {
382 		dev_err(dev, "invalid nflwdth setting of %d\n",
383 			st->nflwdth_reg);
384 		return -EINVAL;
385 	}
386 
387 	indio_dev->name = spi_get_device_id(spi)->name;
388 	indio_dev->channels = as3935_channels;
389 	indio_dev->num_channels = ARRAY_SIZE(as3935_channels);
390 	indio_dev->modes = INDIO_DIRECT_MODE;
391 	indio_dev->info = &as3935_info;
392 
393 	trig = devm_iio_trigger_alloc(dev, "%s-dev%d",
394 				      indio_dev->name,
395 				      iio_device_id(indio_dev));
396 
397 	if (!trig)
398 		return -ENOMEM;
399 
400 	st->trig = trig;
401 	st->noise_tripped = jiffies - HZ;
402 	iio_trigger_set_drvdata(trig, indio_dev);
403 
404 	ret = devm_iio_trigger_register(dev, trig);
405 	if (ret) {
406 		dev_err(dev, "failed to register trigger\n");
407 		return ret;
408 	}
409 
410 	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
411 					      iio_pollfunc_store_time,
412 					      as3935_trigger_handler, NULL);
413 
414 	if (ret) {
415 		dev_err(dev, "cannot setup iio trigger\n");
416 		return ret;
417 	}
418 
419 	calibrate_as3935(st);
420 
421 	ret = devm_delayed_work_autocancel(dev, &st->work, as3935_event_work);
422 	if (ret)
423 		return ret;
424 
425 	ret = devm_request_irq(dev, spi->irq,
426 				&as3935_interrupt_handler,
427 				IRQF_TRIGGER_RISING,
428 				dev_name(dev),
429 				indio_dev);
430 
431 	if (ret)
432 		return ret;
433 
434 	ret = devm_iio_device_register(dev, indio_dev);
435 	if (ret < 0) {
436 		dev_err(dev, "unable to register device\n");
437 		return ret;
438 	}
439 	return 0;
440 }
441 
442 static const struct of_device_id as3935_of_match[] = {
443 	{ .compatible = "ams,as3935", },
444 	{ }
445 };
446 MODULE_DEVICE_TABLE(of, as3935_of_match);
447 
448 static const struct spi_device_id as3935_id[] = {
449 	{ .name = "as3935" },
450 	{ }
451 };
452 MODULE_DEVICE_TABLE(spi, as3935_id);
453 
454 static struct spi_driver as3935_driver = {
455 	.driver = {
456 		.name	= "as3935",
457 		.of_match_table = as3935_of_match,
458 		.pm	= pm_sleep_ptr(&as3935_pm_ops),
459 	},
460 	.probe		= as3935_probe,
461 	.id_table	= as3935_id,
462 };
463 module_spi_driver(as3935_driver);
464 
465 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
466 MODULE_DESCRIPTION("AS3935 lightning sensor");
467 MODULE_LICENSE("GPL");
468