1/*
2 * as3935.c - Support for AS3935 Franklin lightning sensor
3 *
4 * Copyright (C) 2014 Matt Ranostay <mranostay@gmail.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 */
17
18#include <linux/module.h>
19#include <linux/init.h>
20#include <linux/interrupt.h>
21#include <linux/delay.h>
22#include <linux/workqueue.h>
23#include <linux/mutex.h>
24#include <linux/err.h>
25#include <linux/irq.h>
26#include <linux/gpio.h>
27#include <linux/spi/spi.h>
28#include <linux/iio/iio.h>
29#include <linux/iio/sysfs.h>
30#include <linux/iio/trigger.h>
31#include <linux/iio/trigger_consumer.h>
32#include <linux/iio/buffer.h>
33#include <linux/iio/triggered_buffer.h>
34#include <linux/of_gpio.h>
35
36
37#define AS3935_AFE_GAIN		0x00
38#define AS3935_AFE_MASK		0x3F
39#define AS3935_AFE_GAIN_MAX	0x1F
40#define AS3935_AFE_PWR_BIT	BIT(0)
41
42#define AS3935_INT		0x03
43#define AS3935_INT_MASK		0x07
44#define AS3935_EVENT_INT	BIT(3)
45#define AS3935_NOISE_INT	BIT(1)
46
47#define AS3935_DATA		0x07
48#define AS3935_DATA_MASK	0x3F
49
50#define AS3935_TUNE_CAP		0x08
51#define AS3935_CALIBRATE	0x3D
52
53#define AS3935_WRITE_DATA	BIT(15)
54#define AS3935_READ_DATA	BIT(14)
55#define AS3935_ADDRESS(x)	((x) << 8)
56
57#define MAX_PF_CAP		120
58#define TUNE_CAP_DIV		8
59
60struct as3935_state {
61	struct spi_device *spi;
62	struct iio_trigger *trig;
63	struct mutex lock;
64	struct delayed_work work;
65
66	u32 tune_cap;
67	u8 buf[2] ____cacheline_aligned;
68};
69
70static 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		.scan_index     = 0,
77		.scan_type = {
78			.sign           = 'u',
79			.realbits       = 6,
80			.storagebits    = 8,
81		},
82	},
83	IIO_CHAN_SOFT_TIMESTAMP(1),
84};
85
86static int as3935_read(struct as3935_state *st, unsigned int reg, int *val)
87{
88	u8 cmd;
89	int ret;
90
91	cmd = (AS3935_READ_DATA | AS3935_ADDRESS(reg)) >> 8;
92	ret = spi_w8r8(st->spi, cmd);
93	if (ret < 0)
94		return ret;
95	*val = ret;
96
97	return 0;
98}
99
100static int as3935_write(struct as3935_state *st,
101				unsigned int reg,
102				unsigned int val)
103{
104	u8 *buf = st->buf;
105
106	buf[0] = (AS3935_WRITE_DATA | AS3935_ADDRESS(reg)) >> 8;
107	buf[1] = val;
108
109	return spi_write(st->spi, buf, 2);
110}
111
112static ssize_t as3935_sensor_sensitivity_show(struct device *dev,
113					struct device_attribute *attr,
114					char *buf)
115{
116	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
117	int val, ret;
118
119	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
120	if (ret)
121		return ret;
122	val = (val & AS3935_AFE_MASK) >> 1;
123
124	return sprintf(buf, "%d\n", val);
125}
126
127static ssize_t as3935_sensor_sensitivity_store(struct device *dev,
128					struct device_attribute *attr,
129					const char *buf, size_t len)
130{
131	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
132	unsigned long val;
133	int ret;
134
135	ret = kstrtoul((const char *) buf, 10, &val);
136	if (ret)
137		return -EINVAL;
138
139	if (val > AS3935_AFE_GAIN_MAX)
140		return -EINVAL;
141
142	as3935_write(st, AS3935_AFE_GAIN, val << 1);
143
144	return len;
145}
146
147static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
148	as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0);
149
150
151static struct attribute *as3935_attributes[] = {
152	&iio_dev_attr_sensor_sensitivity.dev_attr.attr,
153	NULL,
154};
155
156static struct attribute_group as3935_attribute_group = {
157	.attrs = as3935_attributes,
158};
159
160static int as3935_read_raw(struct iio_dev *indio_dev,
161			   struct iio_chan_spec const *chan,
162			   int *val,
163			   int *val2,
164			   long m)
165{
166	struct as3935_state *st = iio_priv(indio_dev);
167	int ret;
168
169
170	switch (m) {
171	case IIO_CHAN_INFO_PROCESSED:
172	case IIO_CHAN_INFO_RAW:
173		*val2 = 0;
174		ret = as3935_read(st, AS3935_DATA, val);
175		if (ret)
176			return ret;
177
178		if (m == IIO_CHAN_INFO_RAW)
179			return IIO_VAL_INT;
180
181		/* storm out of range */
182		if (*val == AS3935_DATA_MASK)
183			return -EINVAL;
184		*val *= 1000;
185		break;
186	default:
187		return -EINVAL;
188	}
189
190	return IIO_VAL_INT;
191}
192
193static const struct iio_info as3935_info = {
194	.driver_module = THIS_MODULE,
195	.attrs = &as3935_attribute_group,
196	.read_raw = &as3935_read_raw,
197};
198
199static irqreturn_t as3935_trigger_handler(int irq, void *private)
200{
201	struct iio_poll_func *pf = private;
202	struct iio_dev *indio_dev = pf->indio_dev;
203	struct as3935_state *st = iio_priv(indio_dev);
204	int val, ret;
205
206	ret = as3935_read(st, AS3935_DATA, &val);
207	if (ret)
208		goto err_read;
209	val &= AS3935_DATA_MASK;
210	val *= 1000;
211
212	iio_push_to_buffers_with_timestamp(indio_dev, &val, pf->timestamp);
213err_read:
214	iio_trigger_notify_done(indio_dev->trig);
215
216	return IRQ_HANDLED;
217}
218
219static const struct iio_trigger_ops iio_interrupt_trigger_ops = {
220	.owner = THIS_MODULE,
221};
222
223static void as3935_event_work(struct work_struct *work)
224{
225	struct as3935_state *st;
226	int val;
227
228	st = container_of(work, struct as3935_state, work.work);
229
230	as3935_read(st, AS3935_INT, &val);
231	val &= AS3935_INT_MASK;
232
233	switch (val) {
234	case AS3935_EVENT_INT:
235		iio_trigger_poll(st->trig);
236		break;
237	case AS3935_NOISE_INT:
238		dev_warn(&st->spi->dev, "noise level is too high");
239		break;
240	}
241}
242
243static irqreturn_t as3935_interrupt_handler(int irq, void *private)
244{
245	struct iio_dev *indio_dev = private;
246	struct as3935_state *st = iio_priv(indio_dev);
247
248	/*
249	 * Delay work for >2 milliseconds after an interrupt to allow
250	 * estimated distance to recalculated.
251	 */
252
253	schedule_delayed_work(&st->work, msecs_to_jiffies(3));
254
255	return IRQ_HANDLED;
256}
257
258static void calibrate_as3935(struct as3935_state *st)
259{
260	mutex_lock(&st->lock);
261
262	/* mask disturber interrupt bit */
263	as3935_write(st, AS3935_INT, BIT(5));
264
265	as3935_write(st, AS3935_CALIBRATE, 0x96);
266	as3935_write(st, AS3935_TUNE_CAP,
267		BIT(5) | (st->tune_cap / TUNE_CAP_DIV));
268
269	mdelay(2);
270	as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV));
271
272	mutex_unlock(&st->lock);
273}
274
275#ifdef CONFIG_PM_SLEEP
276static int as3935_suspend(struct device *dev)
277{
278	struct iio_dev *indio_dev = dev_get_drvdata(dev);
279	struct as3935_state *st = iio_priv(indio_dev);
280	int val, ret;
281
282	mutex_lock(&st->lock);
283	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
284	if (ret)
285		goto err_suspend;
286	val |= AS3935_AFE_PWR_BIT;
287
288	ret = as3935_write(st, AS3935_AFE_GAIN, val);
289
290err_suspend:
291	mutex_unlock(&st->lock);
292
293	return ret;
294}
295
296static int as3935_resume(struct device *dev)
297{
298	struct iio_dev *indio_dev = dev_get_drvdata(dev);
299	struct as3935_state *st = iio_priv(indio_dev);
300	int val, ret;
301
302	mutex_lock(&st->lock);
303	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
304	if (ret)
305		goto err_resume;
306	val &= ~AS3935_AFE_PWR_BIT;
307	ret = as3935_write(st, AS3935_AFE_GAIN, val);
308
309err_resume:
310	mutex_unlock(&st->lock);
311
312	return ret;
313}
314
315static SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
316#define AS3935_PM_OPS (&as3935_pm_ops)
317
318#else
319#define AS3935_PM_OPS NULL
320#endif
321
322static int as3935_probe(struct spi_device *spi)
323{
324	struct iio_dev *indio_dev;
325	struct iio_trigger *trig;
326	struct as3935_state *st;
327	struct device_node *np = spi->dev.of_node;
328	int ret;
329
330	/* Be sure lightning event interrupt is specified */
331	if (!spi->irq) {
332		dev_err(&spi->dev, "unable to get event interrupt\n");
333		return -EINVAL;
334	}
335
336	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
337	if (!indio_dev)
338		return -ENOMEM;
339
340	st = iio_priv(indio_dev);
341	st->spi = spi;
342	st->tune_cap = 0;
343
344	spi_set_drvdata(spi, indio_dev);
345	mutex_init(&st->lock);
346	INIT_DELAYED_WORK(&st->work, as3935_event_work);
347
348	ret = of_property_read_u32(np,
349			"ams,tuning-capacitor-pf", &st->tune_cap);
350	if (ret) {
351		st->tune_cap = 0;
352		dev_warn(&spi->dev,
353			"no tuning-capacitor-pf set, defaulting to %d",
354			st->tune_cap);
355	}
356
357	if (st->tune_cap > MAX_PF_CAP) {
358		dev_err(&spi->dev,
359			"wrong tuning-capacitor-pf setting of %d\n",
360			st->tune_cap);
361		return -EINVAL;
362	}
363
364	indio_dev->dev.parent = &spi->dev;
365	indio_dev->name = spi_get_device_id(spi)->name;
366	indio_dev->channels = as3935_channels;
367	indio_dev->num_channels = ARRAY_SIZE(as3935_channels);
368	indio_dev->modes = INDIO_DIRECT_MODE;
369	indio_dev->info = &as3935_info;
370
371	trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d",
372				      indio_dev->name, indio_dev->id);
373
374	if (!trig)
375		return -ENOMEM;
376
377	st->trig = trig;
378	trig->dev.parent = indio_dev->dev.parent;
379	iio_trigger_set_drvdata(trig, indio_dev);
380	trig->ops = &iio_interrupt_trigger_ops;
381
382	ret = iio_trigger_register(trig);
383	if (ret) {
384		dev_err(&spi->dev, "failed to register trigger\n");
385		return ret;
386	}
387
388	ret = iio_triggered_buffer_setup(indio_dev, NULL,
389		&as3935_trigger_handler, NULL);
390
391	if (ret) {
392		dev_err(&spi->dev, "cannot setup iio trigger\n");
393		goto unregister_trigger;
394	}
395
396	calibrate_as3935(st);
397
398	ret = devm_request_irq(&spi->dev, spi->irq,
399				&as3935_interrupt_handler,
400				IRQF_TRIGGER_RISING,
401				dev_name(&spi->dev),
402				indio_dev);
403
404	if (ret) {
405		dev_err(&spi->dev, "unable to request irq\n");
406		goto unregister_buffer;
407	}
408
409	ret = iio_device_register(indio_dev);
410	if (ret < 0) {
411		dev_err(&spi->dev, "unable to register device\n");
412		goto unregister_buffer;
413	}
414	return 0;
415
416unregister_buffer:
417	iio_triggered_buffer_cleanup(indio_dev);
418
419unregister_trigger:
420	iio_trigger_unregister(st->trig);
421
422	return ret;
423}
424
425static int as3935_remove(struct spi_device *spi)
426{
427	struct iio_dev *indio_dev = spi_get_drvdata(spi);
428	struct as3935_state *st = iio_priv(indio_dev);
429
430	iio_device_unregister(indio_dev);
431	iio_triggered_buffer_cleanup(indio_dev);
432	iio_trigger_unregister(st->trig);
433
434	return 0;
435}
436
437static const struct spi_device_id as3935_id[] = {
438	{"as3935", 0},
439	{},
440};
441MODULE_DEVICE_TABLE(spi, as3935_id);
442
443static struct spi_driver as3935_driver = {
444	.driver = {
445		.name	= "as3935",
446		.owner	= THIS_MODULE,
447		.pm	= AS3935_PM_OPS,
448	},
449	.probe		= as3935_probe,
450	.remove		= as3935_remove,
451	.id_table	= as3935_id,
452};
453module_spi_driver(as3935_driver);
454
455MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
456MODULE_DESCRIPTION("AS3935 lightning sensor");
457MODULE_LICENSE("GPL");
458MODULE_ALIAS("spi:as3935");
459