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/mod_devicetable.h>
11 #include <linux/init.h>
12 #include <linux/interrupt.h>
13 #include <linux/delay.h>
14 #include <linux/workqueue.h>
15 #include <linux/devm-helpers.h>
16 #include <linux/mutex.h>
17 #include <linux/err.h>
18 #include <linux/irq.h>
19 #include <linux/spi/spi.h>
20 #include <linux/iio/iio.h>
21 #include <linux/iio/sysfs.h>
22 #include <linux/iio/trigger.h>
23 #include <linux/iio/trigger_consumer.h>
24 #include <linux/iio/buffer.h>
25 #include <linux/iio/triggered_buffer.h>
26 
27 #define AS3935_AFE_GAIN		0x00
28 #define AS3935_AFE_MASK		0x3F
29 #define AS3935_AFE_GAIN_MAX	0x1F
30 #define AS3935_AFE_PWR_BIT	BIT(0)
31 
32 #define AS3935_NFLWDTH		0x01
33 #define AS3935_NFLWDTH_MASK	0x7f
34 
35 #define AS3935_INT		0x03
36 #define AS3935_INT_MASK		0x0f
37 #define AS3935_DISTURB_INT	BIT(2)
38 #define AS3935_EVENT_INT	BIT(3)
39 #define AS3935_NOISE_INT	BIT(0)
40 
41 #define AS3935_DATA		0x07
42 #define AS3935_DATA_MASK	0x3F
43 
44 #define AS3935_TUNE_CAP		0x08
45 #define AS3935_DEFAULTS		0x3C
46 #define AS3935_CALIBRATE	0x3D
47 
48 #define AS3935_READ_DATA	BIT(14)
49 #define AS3935_ADDRESS(x)	((x) << 8)
50 
51 #define MAX_PF_CAP		120
52 #define TUNE_CAP_DIV		8
53 
54 struct as3935_state {
55 	struct spi_device *spi;
56 	struct iio_trigger *trig;
57 	struct mutex lock;
58 	struct delayed_work work;
59 
60 	unsigned long noise_tripped;
61 	u32 tune_cap;
62 	u32 nflwdth_reg;
63 	/* Ensure timestamp is naturally aligned */
64 	struct {
65 		u8 chan;
66 		s64 timestamp __aligned(8);
67 	} scan;
68 	u8 buf[2] __aligned(IIO_DMA_MINALIGN);
69 };
70 
71 static const struct iio_chan_spec as3935_channels[] = {
72 	{
73 		.type           = IIO_PROXIMITY,
74 		.info_mask_separate =
75 			BIT(IIO_CHAN_INFO_RAW) |
76 			BIT(IIO_CHAN_INFO_PROCESSED) |
77 			BIT(IIO_CHAN_INFO_SCALE),
78 		.scan_index     = 0,
79 		.scan_type = {
80 			.sign           = 'u',
81 			.realbits       = 6,
82 			.storagebits    = 8,
83 		},
84 	},
85 	IIO_CHAN_SOFT_TIMESTAMP(1),
86 };
87 
as3935_read(struct as3935_state * st,unsigned int reg,int * val)88 static int as3935_read(struct as3935_state *st, unsigned int reg, int *val)
89 {
90 	u8 cmd;
91 	int ret;
92 
93 	cmd = (AS3935_READ_DATA | AS3935_ADDRESS(reg)) >> 8;
94 	ret = spi_w8r8(st->spi, cmd);
95 	if (ret < 0)
96 		return ret;
97 	*val = ret;
98 
99 	return 0;
100 }
101 
as3935_write(struct as3935_state * st,unsigned int reg,unsigned int val)102 static int as3935_write(struct as3935_state *st,
103 				unsigned int reg,
104 				unsigned int val)
105 {
106 	u8 *buf = st->buf;
107 
108 	buf[0] = AS3935_ADDRESS(reg) >> 8;
109 	buf[1] = val;
110 
111 	return spi_write(st->spi, buf, 2);
112 }
113 
as3935_sensor_sensitivity_show(struct device * dev,struct device_attribute * attr,char * buf)114 static ssize_t as3935_sensor_sensitivity_show(struct device *dev,
115 					struct device_attribute *attr,
116 					char *buf)
117 {
118 	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
119 	int val, ret;
120 
121 	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
122 	if (ret)
123 		return ret;
124 	val = (val & AS3935_AFE_MASK) >> 1;
125 
126 	return sysfs_emit(buf, "%d\n", val);
127 }
128 
as3935_sensor_sensitivity_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)129 static ssize_t as3935_sensor_sensitivity_store(struct device *dev,
130 					struct device_attribute *attr,
131 					const char *buf, size_t len)
132 {
133 	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
134 	unsigned long val;
135 	int ret;
136 
137 	ret = kstrtoul(buf, 10, &val);
138 	if (ret)
139 		return -EINVAL;
140 
141 	if (val > AS3935_AFE_GAIN_MAX)
142 		return -EINVAL;
143 
144 	as3935_write(st, AS3935_AFE_GAIN, val << 1);
145 
146 	return len;
147 }
148 
as3935_noise_level_tripped_show(struct device * dev,struct device_attribute * attr,char * buf)149 static ssize_t as3935_noise_level_tripped_show(struct device *dev,
150 					struct device_attribute *attr,
151 					char *buf)
152 {
153 	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
154 	int ret;
155 
156 	mutex_lock(&st->lock);
157 	ret = sysfs_emit(buf, "%d\n", !time_after(jiffies, st->noise_tripped + HZ));
158 	mutex_unlock(&st->lock);
159 
160 	return ret;
161 }
162 
163 static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
164 	as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0);
165 
166 static IIO_DEVICE_ATTR(noise_level_tripped, S_IRUGO,
167 	as3935_noise_level_tripped_show, NULL, 0);
168 
169 static struct attribute *as3935_attributes[] = {
170 	&iio_dev_attr_sensor_sensitivity.dev_attr.attr,
171 	&iio_dev_attr_noise_level_tripped.dev_attr.attr,
172 	NULL,
173 };
174 
175 static const struct attribute_group as3935_attribute_group = {
176 	.attrs = as3935_attributes,
177 };
178 
as3935_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)179 static int as3935_read_raw(struct iio_dev *indio_dev,
180 			   struct iio_chan_spec const *chan,
181 			   int *val,
182 			   int *val2,
183 			   long m)
184 {
185 	struct as3935_state *st = iio_priv(indio_dev);
186 	int ret;
187 
188 
189 	switch (m) {
190 	case IIO_CHAN_INFO_PROCESSED:
191 	case IIO_CHAN_INFO_RAW:
192 		*val2 = 0;
193 		ret = as3935_read(st, AS3935_DATA, val);
194 		if (ret)
195 			return ret;
196 
197 		/* storm out of range */
198 		if (*val == AS3935_DATA_MASK)
199 			return -EINVAL;
200 
201 		if (m == IIO_CHAN_INFO_RAW)
202 			return IIO_VAL_INT;
203 
204 		if (m == IIO_CHAN_INFO_PROCESSED)
205 			*val *= 1000;
206 		break;
207 	case IIO_CHAN_INFO_SCALE:
208 		*val = 1000;
209 		break;
210 	default:
211 		return -EINVAL;
212 	}
213 
214 	return IIO_VAL_INT;
215 }
216 
217 static const struct iio_info as3935_info = {
218 	.attrs = &as3935_attribute_group,
219 	.read_raw = &as3935_read_raw,
220 };
221 
as3935_trigger_handler(int irq,void * private)222 static irqreturn_t as3935_trigger_handler(int irq, void *private)
223 {
224 	struct iio_poll_func *pf = private;
225 	struct iio_dev *indio_dev = pf->indio_dev;
226 	struct as3935_state *st = iio_priv(indio_dev);
227 	int val, ret;
228 
229 	ret = as3935_read(st, AS3935_DATA, &val);
230 	if (ret)
231 		goto err_read;
232 
233 	st->scan.chan = val & AS3935_DATA_MASK;
234 	iio_push_to_buffers_with_timestamp(indio_dev, &st->scan,
235 					   iio_get_time_ns(indio_dev));
236 err_read:
237 	iio_trigger_notify_done(indio_dev->trig);
238 
239 	return IRQ_HANDLED;
240 }
241 
as3935_event_work(struct work_struct * work)242 static void as3935_event_work(struct work_struct *work)
243 {
244 	struct as3935_state *st;
245 	int val;
246 	int ret;
247 
248 	st = container_of(work, struct as3935_state, work.work);
249 
250 	ret = as3935_read(st, AS3935_INT, &val);
251 	if (ret) {
252 		dev_warn(&st->spi->dev, "read error\n");
253 		return;
254 	}
255 
256 	val &= AS3935_INT_MASK;
257 
258 	switch (val) {
259 	case AS3935_EVENT_INT:
260 		iio_trigger_poll_chained(st->trig);
261 		break;
262 	case AS3935_DISTURB_INT:
263 	case AS3935_NOISE_INT:
264 		mutex_lock(&st->lock);
265 		st->noise_tripped = jiffies;
266 		mutex_unlock(&st->lock);
267 		dev_warn(&st->spi->dev, "noise level is too high\n");
268 		break;
269 	}
270 }
271 
as3935_interrupt_handler(int irq,void * private)272 static irqreturn_t as3935_interrupt_handler(int irq, void *private)
273 {
274 	struct iio_dev *indio_dev = private;
275 	struct as3935_state *st = iio_priv(indio_dev);
276 
277 	/*
278 	 * Delay work for >2 milliseconds after an interrupt to allow
279 	 * estimated distance to recalculated.
280 	 */
281 
282 	schedule_delayed_work(&st->work, msecs_to_jiffies(3));
283 
284 	return IRQ_HANDLED;
285 }
286 
calibrate_as3935(struct as3935_state * st)287 static void calibrate_as3935(struct as3935_state *st)
288 {
289 	as3935_write(st, AS3935_DEFAULTS, 0x96);
290 	as3935_write(st, AS3935_CALIBRATE, 0x96);
291 	as3935_write(st, AS3935_TUNE_CAP,
292 		BIT(5) | (st->tune_cap / TUNE_CAP_DIV));
293 
294 	mdelay(2);
295 	as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV));
296 	as3935_write(st, AS3935_NFLWDTH, st->nflwdth_reg);
297 }
298 
as3935_suspend(struct device * dev)299 static int as3935_suspend(struct device *dev)
300 {
301 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
302 	struct as3935_state *st = iio_priv(indio_dev);
303 	int val, ret;
304 
305 	mutex_lock(&st->lock);
306 	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
307 	if (ret)
308 		goto err_suspend;
309 	val |= AS3935_AFE_PWR_BIT;
310 
311 	ret = as3935_write(st, AS3935_AFE_GAIN, val);
312 
313 err_suspend:
314 	mutex_unlock(&st->lock);
315 
316 	return ret;
317 }
318 
as3935_resume(struct device * dev)319 static int as3935_resume(struct device *dev)
320 {
321 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
322 	struct as3935_state *st = iio_priv(indio_dev);
323 	int val, ret;
324 
325 	mutex_lock(&st->lock);
326 	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
327 	if (ret)
328 		goto err_resume;
329 	val &= ~AS3935_AFE_PWR_BIT;
330 	ret = as3935_write(st, AS3935_AFE_GAIN, val);
331 
332 	calibrate_as3935(st);
333 
334 err_resume:
335 	mutex_unlock(&st->lock);
336 
337 	return ret;
338 }
339 
340 static DEFINE_SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
341 
as3935_probe(struct spi_device * spi)342 static int as3935_probe(struct spi_device *spi)
343 {
344 	struct device *dev = &spi->dev;
345 	struct iio_dev *indio_dev;
346 	struct iio_trigger *trig;
347 	struct as3935_state *st;
348 	int ret;
349 
350 	/* Be sure lightning event interrupt is specified */
351 	if (!spi->irq) {
352 		dev_err(dev, "unable to get event interrupt\n");
353 		return -EINVAL;
354 	}
355 
356 	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
357 	if (!indio_dev)
358 		return -ENOMEM;
359 
360 	st = iio_priv(indio_dev);
361 	st->spi = spi;
362 
363 	spi_set_drvdata(spi, indio_dev);
364 	mutex_init(&st->lock);
365 
366 	ret = device_property_read_u32(dev,
367 			"ams,tuning-capacitor-pf", &st->tune_cap);
368 	if (ret) {
369 		st->tune_cap = 0;
370 		dev_warn(dev, "no tuning-capacitor-pf set, defaulting to %d",
371 			st->tune_cap);
372 	}
373 
374 	if (st->tune_cap > MAX_PF_CAP) {
375 		dev_err(dev, "wrong tuning-capacitor-pf setting of %d\n",
376 			st->tune_cap);
377 		return -EINVAL;
378 	}
379 
380 	ret = device_property_read_u32(dev,
381 			"ams,nflwdth", &st->nflwdth_reg);
382 	if (!ret && st->nflwdth_reg > AS3935_NFLWDTH_MASK) {
383 		dev_err(dev, "invalid nflwdth setting of %d\n",
384 			st->nflwdth_reg);
385 		return -EINVAL;
386 	}
387 
388 	indio_dev->name = spi_get_device_id(spi)->name;
389 	indio_dev->channels = as3935_channels;
390 	indio_dev->num_channels = ARRAY_SIZE(as3935_channels);
391 	indio_dev->modes = INDIO_DIRECT_MODE;
392 	indio_dev->info = &as3935_info;
393 
394 	trig = devm_iio_trigger_alloc(dev, "%s-dev%d",
395 				      indio_dev->name,
396 				      iio_device_id(indio_dev));
397 
398 	if (!trig)
399 		return -ENOMEM;
400 
401 	st->trig = trig;
402 	st->noise_tripped = jiffies - HZ;
403 	iio_trigger_set_drvdata(trig, indio_dev);
404 
405 	ret = devm_iio_trigger_register(dev, trig);
406 	if (ret) {
407 		dev_err(dev, "failed to register trigger\n");
408 		return ret;
409 	}
410 
411 	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
412 					      iio_pollfunc_store_time,
413 					      as3935_trigger_handler, NULL);
414 
415 	if (ret) {
416 		dev_err(dev, "cannot setup iio trigger\n");
417 		return ret;
418 	}
419 
420 	calibrate_as3935(st);
421 
422 	ret = devm_delayed_work_autocancel(dev, &st->work, as3935_event_work);
423 	if (ret)
424 		return ret;
425 
426 	ret = devm_request_irq(dev, spi->irq,
427 				&as3935_interrupt_handler,
428 				IRQF_TRIGGER_RISING,
429 				dev_name(dev),
430 				indio_dev);
431 
432 	if (ret) {
433 		dev_err(dev, "unable to request irq\n");
434 		return ret;
435 	}
436 
437 	ret = devm_iio_device_register(dev, indio_dev);
438 	if (ret < 0) {
439 		dev_err(dev, "unable to register device\n");
440 		return ret;
441 	}
442 	return 0;
443 }
444 
445 static const struct of_device_id as3935_of_match[] = {
446 	{ .compatible = "ams,as3935", },
447 	{ /* sentinel */ },
448 };
449 MODULE_DEVICE_TABLE(of, as3935_of_match);
450 
451 static const struct spi_device_id as3935_id[] = {
452 	{"as3935", 0},
453 	{},
454 };
455 MODULE_DEVICE_TABLE(spi, as3935_id);
456 
457 static struct spi_driver as3935_driver = {
458 	.driver = {
459 		.name	= "as3935",
460 		.of_match_table = as3935_of_match,
461 		.pm	= pm_sleep_ptr(&as3935_pm_ops),
462 	},
463 	.probe		= as3935_probe,
464 	.id_table	= as3935_id,
465 };
466 module_spi_driver(as3935_driver);
467 
468 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
469 MODULE_DESCRIPTION("AS3935 lightning sensor");
470 MODULE_LICENSE("GPL");
471