xref: /openbmc/linux/drivers/iio/proximity/as3935.c (revision 4eb5928d) 
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/mutex.h>
15 #include <linux/err.h>
16 #include <linux/irq.h>
17 #include <linux/spi/spi.h>
18 #include <linux/iio/iio.h>
19 #include <linux/iio/sysfs.h>
20 #include <linux/iio/trigger.h>
21 #include <linux/iio/trigger_consumer.h>
22 #include <linux/iio/buffer.h>
23 #include <linux/iio/triggered_buffer.h>
24 
25 #define AS3935_AFE_GAIN		0x00
26 #define AS3935_AFE_MASK		0x3F
27 #define AS3935_AFE_GAIN_MAX	0x1F
28 #define AS3935_AFE_PWR_BIT	BIT(0)
29 
30 #define AS3935_NFLWDTH		0x01
31 #define AS3935_NFLWDTH_MASK	0x7f
32 
33 #define AS3935_INT		0x03
34 #define AS3935_INT_MASK		0x0f
35 #define AS3935_DISTURB_INT	BIT(2)
36 #define AS3935_EVENT_INT	BIT(3)
37 #define AS3935_NOISE_INT	BIT(0)
38 
39 #define AS3935_DATA		0x07
40 #define AS3935_DATA_MASK	0x3F
41 
42 #define AS3935_TUNE_CAP		0x08
43 #define AS3935_DEFAULTS		0x3C
44 #define AS3935_CALIBRATE	0x3D
45 
46 #define AS3935_READ_DATA	BIT(14)
47 #define AS3935_ADDRESS(x)	((x) << 8)
48 
49 #define MAX_PF_CAP		120
50 #define TUNE_CAP_DIV		8
51 
52 struct as3935_state {
53 	struct spi_device *spi;
54 	struct iio_trigger *trig;
55 	struct mutex lock;
56 	struct delayed_work work;
57 
58 	unsigned long noise_tripped;
59 	u32 tune_cap;
60 	u32 nflwdth_reg;
61 	u8 buffer[16]; /* 8-bit data + 56-bit padding + 64-bit timestamp */
62 	u8 buf[2] ____cacheline_aligned;
63 };
64 
65 static const struct iio_chan_spec as3935_channels[] = {
66 	{
67 		.type           = IIO_PROXIMITY,
68 		.info_mask_separate =
69 			BIT(IIO_CHAN_INFO_RAW) |
70 			BIT(IIO_CHAN_INFO_PROCESSED) |
71 			BIT(IIO_CHAN_INFO_SCALE),
72 		.scan_index     = 0,
73 		.scan_type = {
74 			.sign           = 'u',
75 			.realbits       = 6,
76 			.storagebits    = 8,
77 		},
78 	},
79 	IIO_CHAN_SOFT_TIMESTAMP(1),
80 };
81 
82 static int as3935_read(struct as3935_state *st, unsigned int reg, int *val)
83 {
84 	u8 cmd;
85 	int ret;
86 
87 	cmd = (AS3935_READ_DATA | AS3935_ADDRESS(reg)) >> 8;
88 	ret = spi_w8r8(st->spi, cmd);
89 	if (ret < 0)
90 		return ret;
91 	*val = ret;
92 
93 	return 0;
94 }
95 
96 static int as3935_write(struct as3935_state *st,
97 				unsigned int reg,
98 				unsigned int val)
99 {
100 	u8 *buf = st->buf;
101 
102 	buf[0] = AS3935_ADDRESS(reg) >> 8;
103 	buf[1] = val;
104 
105 	return spi_write(st->spi, buf, 2);
106 }
107 
108 static ssize_t as3935_sensor_sensitivity_show(struct device *dev,
109 					struct device_attribute *attr,
110 					char *buf)
111 {
112 	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
113 	int val, ret;
114 
115 	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
116 	if (ret)
117 		return ret;
118 	val = (val & AS3935_AFE_MASK) >> 1;
119 
120 	return sprintf(buf, "%d\n", val);
121 }
122 
123 static ssize_t as3935_sensor_sensitivity_store(struct device *dev,
124 					struct device_attribute *attr,
125 					const char *buf, size_t len)
126 {
127 	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
128 	unsigned long val;
129 	int ret;
130 
131 	ret = kstrtoul((const char *) buf, 10, &val);
132 	if (ret)
133 		return -EINVAL;
134 
135 	if (val > AS3935_AFE_GAIN_MAX)
136 		return -EINVAL;
137 
138 	as3935_write(st, AS3935_AFE_GAIN, val << 1);
139 
140 	return len;
141 }
142 
143 static ssize_t as3935_noise_level_tripped_show(struct device *dev,
144 					struct device_attribute *attr,
145 					char *buf)
146 {
147 	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
148 	int ret;
149 
150 	mutex_lock(&st->lock);
151 	ret = sprintf(buf, "%d\n", !time_after(jiffies, st->noise_tripped + HZ));
152 	mutex_unlock(&st->lock);
153 
154 	return ret;
155 }
156 
157 static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
158 	as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0);
159 
160 static IIO_DEVICE_ATTR(noise_level_tripped, S_IRUGO,
161 	as3935_noise_level_tripped_show, NULL, 0);
162 
163 static struct attribute *as3935_attributes[] = {
164 	&iio_dev_attr_sensor_sensitivity.dev_attr.attr,
165 	&iio_dev_attr_noise_level_tripped.dev_attr.attr,
166 	NULL,
167 };
168 
169 static const struct attribute_group as3935_attribute_group = {
170 	.attrs = as3935_attributes,
171 };
172 
173 static int as3935_read_raw(struct iio_dev *indio_dev,
174 			   struct iio_chan_spec const *chan,
175 			   int *val,
176 			   int *val2,
177 			   long m)
178 {
179 	struct as3935_state *st = iio_priv(indio_dev);
180 	int ret;
181 
182 
183 	switch (m) {
184 	case IIO_CHAN_INFO_PROCESSED:
185 	case IIO_CHAN_INFO_RAW:
186 		*val2 = 0;
187 		ret = as3935_read(st, AS3935_DATA, val);
188 		if (ret)
189 			return ret;
190 
191 		/* storm out of range */
192 		if (*val == AS3935_DATA_MASK)
193 			return -EINVAL;
194 
195 		if (m == IIO_CHAN_INFO_RAW)
196 			return IIO_VAL_INT;
197 
198 		if (m == IIO_CHAN_INFO_PROCESSED)
199 			*val *= 1000;
200 		break;
201 	case IIO_CHAN_INFO_SCALE:
202 		*val = 1000;
203 		break;
204 	default:
205 		return -EINVAL;
206 	}
207 
208 	return IIO_VAL_INT;
209 }
210 
211 static const struct iio_info as3935_info = {
212 	.attrs = &as3935_attribute_group,
213 	.read_raw = &as3935_read_raw,
214 };
215 
216 static irqreturn_t as3935_trigger_handler(int irq, void *private)
217 {
218 	struct iio_poll_func *pf = private;
219 	struct iio_dev *indio_dev = pf->indio_dev;
220 	struct as3935_state *st = iio_priv(indio_dev);
221 	int val, ret;
222 
223 	ret = as3935_read(st, AS3935_DATA, &val);
224 	if (ret)
225 		goto err_read;
226 
227 	st->buffer[0] = val & AS3935_DATA_MASK;
228 	iio_push_to_buffers_with_timestamp(indio_dev, &st->buffer,
229 					   iio_get_time_ns(indio_dev));
230 err_read:
231 	iio_trigger_notify_done(indio_dev->trig);
232 
233 	return IRQ_HANDLED;
234 }
235 
236 static const struct iio_trigger_ops iio_interrupt_trigger_ops = {
237 };
238 
239 static void as3935_event_work(struct work_struct *work)
240 {
241 	struct as3935_state *st;
242 	int val;
243 	int ret;
244 
245 	st = container_of(work, struct as3935_state, work.work);
246 
247 	ret = as3935_read(st, AS3935_INT, &val);
248 	if (ret) {
249 		dev_warn(&st->spi->dev, "read error\n");
250 		return;
251 	}
252 
253 	val &= AS3935_INT_MASK;
254 
255 	switch (val) {
256 	case AS3935_EVENT_INT:
257 		iio_trigger_poll_chained(st->trig);
258 		break;
259 	case AS3935_DISTURB_INT:
260 	case AS3935_NOISE_INT:
261 		mutex_lock(&st->lock);
262 		st->noise_tripped = jiffies;
263 		mutex_unlock(&st->lock);
264 		dev_warn(&st->spi->dev, "noise level is too high\n");
265 		break;
266 	}
267 }
268 
269 static irqreturn_t as3935_interrupt_handler(int irq, void *private)
270 {
271 	struct iio_dev *indio_dev = private;
272 	struct as3935_state *st = iio_priv(indio_dev);
273 
274 	/*
275 	 * Delay work for >2 milliseconds after an interrupt to allow
276 	 * estimated distance to recalculated.
277 	 */
278 
279 	schedule_delayed_work(&st->work, msecs_to_jiffies(3));
280 
281 	return IRQ_HANDLED;
282 }
283 
284 static void calibrate_as3935(struct as3935_state *st)
285 {
286 	as3935_write(st, AS3935_DEFAULTS, 0x96);
287 	as3935_write(st, AS3935_CALIBRATE, 0x96);
288 	as3935_write(st, AS3935_TUNE_CAP,
289 		BIT(5) | (st->tune_cap / TUNE_CAP_DIV));
290 
291 	mdelay(2);
292 	as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV));
293 	as3935_write(st, AS3935_NFLWDTH, st->nflwdth_reg);
294 }
295 
296 #ifdef CONFIG_PM_SLEEP
297 static int as3935_suspend(struct device *dev)
298 {
299 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
300 	struct as3935_state *st = iio_priv(indio_dev);
301 	int val, ret;
302 
303 	mutex_lock(&st->lock);
304 	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
305 	if (ret)
306 		goto err_suspend;
307 	val |= AS3935_AFE_PWR_BIT;
308 
309 	ret = as3935_write(st, AS3935_AFE_GAIN, val);
310 
311 err_suspend:
312 	mutex_unlock(&st->lock);
313 
314 	return ret;
315 }
316 
317 static int as3935_resume(struct device *dev)
318 {
319 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
320 	struct as3935_state *st = iio_priv(indio_dev);
321 	int val, ret;
322 
323 	mutex_lock(&st->lock);
324 	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
325 	if (ret)
326 		goto err_resume;
327 	val &= ~AS3935_AFE_PWR_BIT;
328 	ret = as3935_write(st, AS3935_AFE_GAIN, val);
329 
330 	calibrate_as3935(st);
331 
332 err_resume:
333 	mutex_unlock(&st->lock);
334 
335 	return ret;
336 }
337 
338 static SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
339 #define AS3935_PM_OPS (&as3935_pm_ops)
340 
341 #else
342 #define AS3935_PM_OPS NULL
343 #endif
344 
345 static void as3935_stop_work(void *data)
346 {
347 	struct iio_dev *indio_dev = data;
348 	struct as3935_state *st = iio_priv(indio_dev);
349 
350 	cancel_delayed_work_sync(&st->work);
351 }
352 
353 static int as3935_probe(struct spi_device *spi)
354 {
355 	struct iio_dev *indio_dev;
356 	struct iio_trigger *trig;
357 	struct as3935_state *st;
358 	struct device_node *np = spi->dev.of_node;
359 	int ret;
360 
361 	/* Be sure lightning event interrupt is specified */
362 	if (!spi->irq) {
363 		dev_err(&spi->dev, "unable to get event interrupt\n");
364 		return -EINVAL;
365 	}
366 
367 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
368 	if (!indio_dev)
369 		return -ENOMEM;
370 
371 	st = iio_priv(indio_dev);
372 	st->spi = spi;
373 
374 	spi_set_drvdata(spi, indio_dev);
375 	mutex_init(&st->lock);
376 
377 	ret = of_property_read_u32(np,
378 			"ams,tuning-capacitor-pf", &st->tune_cap);
379 	if (ret) {
380 		st->tune_cap = 0;
381 		dev_warn(&spi->dev,
382 			"no tuning-capacitor-pf set, defaulting to %d",
383 			st->tune_cap);
384 	}
385 
386 	if (st->tune_cap > MAX_PF_CAP) {
387 		dev_err(&spi->dev,
388 			"wrong tuning-capacitor-pf setting of %d\n",
389 			st->tune_cap);
390 		return -EINVAL;
391 	}
392 
393 	ret = of_property_read_u32(np,
394 			"ams,nflwdth", &st->nflwdth_reg);
395 	if (!ret && st->nflwdth_reg > AS3935_NFLWDTH_MASK) {
396 		dev_err(&spi->dev,
397 			"invalid nflwdth setting of %d\n",
398 			st->nflwdth_reg);
399 		return -EINVAL;
400 	}
401 
402 	indio_dev->name = spi_get_device_id(spi)->name;
403 	indio_dev->channels = as3935_channels;
404 	indio_dev->num_channels = ARRAY_SIZE(as3935_channels);
405 	indio_dev->modes = INDIO_DIRECT_MODE;
406 	indio_dev->info = &as3935_info;
407 
408 	trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d",
409 				      indio_dev->name, indio_dev->id);
410 
411 	if (!trig)
412 		return -ENOMEM;
413 
414 	st->trig = trig;
415 	st->noise_tripped = jiffies - HZ;
416 	trig->dev.parent = indio_dev->dev.parent;
417 	iio_trigger_set_drvdata(trig, indio_dev);
418 	trig->ops = &iio_interrupt_trigger_ops;
419 
420 	ret = devm_iio_trigger_register(&spi->dev, trig);
421 	if (ret) {
422 		dev_err(&spi->dev, "failed to register trigger\n");
423 		return ret;
424 	}
425 
426 	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
427 					      iio_pollfunc_store_time,
428 					      as3935_trigger_handler, NULL);
429 
430 	if (ret) {
431 		dev_err(&spi->dev, "cannot setup iio trigger\n");
432 		return ret;
433 	}
434 
435 	calibrate_as3935(st);
436 
437 	INIT_DELAYED_WORK(&st->work, as3935_event_work);
438 	ret = devm_add_action(&spi->dev, as3935_stop_work, indio_dev);
439 	if (ret)
440 		return ret;
441 
442 	ret = devm_request_irq(&spi->dev, spi->irq,
443 				&as3935_interrupt_handler,
444 				IRQF_TRIGGER_RISING,
445 				dev_name(&spi->dev),
446 				indio_dev);
447 
448 	if (ret) {
449 		dev_err(&spi->dev, "unable to request irq\n");
450 		return ret;
451 	}
452 
453 	ret = devm_iio_device_register(&spi->dev, indio_dev);
454 	if (ret < 0) {
455 		dev_err(&spi->dev, "unable to register device\n");
456 		return ret;
457 	}
458 	return 0;
459 }
460 
461 static const struct of_device_id as3935_of_match[] = {
462 	{ .compatible = "ams,as3935", },
463 	{ /* sentinel */ },
464 };
465 MODULE_DEVICE_TABLE(of, as3935_of_match);
466 
467 static const struct spi_device_id as3935_id[] = {
468 	{"as3935", 0},
469 	{},
470 };
471 MODULE_DEVICE_TABLE(spi, as3935_id);
472 
473 static struct spi_driver as3935_driver = {
474 	.driver = {
475 		.name	= "as3935",
476 		.of_match_table = of_match_ptr(as3935_of_match),
477 		.pm	= AS3935_PM_OPS,
478 	},
479 	.probe		= as3935_probe,
480 	.id_table	= as3935_id,
481 };
482 module_spi_driver(as3935_driver);
483 
484 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
485 MODULE_DESCRIPTION("AS3935 lightning sensor");
486 MODULE_LICENSE("GPL");
487