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
54struct 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
71static 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
88static 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
102static 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
114static 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
129static 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
149static 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
163static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
164	as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0);
165
166static IIO_DEVICE_ATTR(noise_level_tripped, S_IRUGO,
167	as3935_noise_level_tripped_show, NULL, 0);
168
169static 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
175static const struct attribute_group as3935_attribute_group = {
176	.attrs = as3935_attributes,
177};
178
179static 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
217static const struct iio_info as3935_info = {
218	.attrs = &as3935_attribute_group,
219	.read_raw = &as3935_read_raw,
220};
221
222static 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));
236err_read:
237	iio_trigger_notify_done(indio_dev->trig);
238
239	return IRQ_HANDLED;
240}
241
242static 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_nested(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
272static 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
287static 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
299static 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
313err_suspend:
314	mutex_unlock(&st->lock);
315
316	return ret;
317}
318
319static 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
334err_resume:
335	mutex_unlock(&st->lock);
336
337	return ret;
338}
339
340static DEFINE_SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
341
342static 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
445static const struct of_device_id as3935_of_match[] = {
446	{ .compatible = "ams,as3935", },
447	{ /* sentinel */ },
448};
449MODULE_DEVICE_TABLE(of, as3935_of_match);
450
451static const struct spi_device_id as3935_id[] = {
452	{"as3935", 0},
453	{},
454};
455MODULE_DEVICE_TABLE(spi, as3935_id);
456
457static 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};
466module_spi_driver(as3935_driver);
467
468MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
469MODULE_DESCRIPTION("AS3935 lightning sensor");
470MODULE_LICENSE("GPL");
471