xref: /linux/drivers/iio/proximity/as3935.c (revision e58e871becec2d3b04ed91c0c16fe8deac9c9dfa) 
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_READ_DATA	BIT(14)
54 #define AS3935_ADDRESS(x)	((x) << 8)
55 
56 #define MAX_PF_CAP		120
57 #define TUNE_CAP_DIV		8
58 
59 struct as3935_state {
60 	struct spi_device *spi;
61 	struct iio_trigger *trig;
62 	struct mutex lock;
63 	struct delayed_work work;
64 
65 	u32 tune_cap;
66 	u8 buffer[16]; /* 8-bit data + 56-bit padding + 64-bit timestamp */
67 	u8 buf[2] ____cacheline_aligned;
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 sprintf(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((const char *) 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 IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
149 	as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0);
150 
151 
152 static struct attribute *as3935_attributes[] = {
153 	&iio_dev_attr_sensor_sensitivity.dev_attr.attr,
154 	NULL,
155 };
156 
157 static const struct attribute_group as3935_attribute_group = {
158 	.attrs = as3935_attributes,
159 };
160 
161 static int as3935_read_raw(struct iio_dev *indio_dev,
162 			   struct iio_chan_spec const *chan,
163 			   int *val,
164 			   int *val2,
165 			   long m)
166 {
167 	struct as3935_state *st = iio_priv(indio_dev);
168 	int ret;
169 
170 
171 	switch (m) {
172 	case IIO_CHAN_INFO_PROCESSED:
173 	case IIO_CHAN_INFO_RAW:
174 		*val2 = 0;
175 		ret = as3935_read(st, AS3935_DATA, val);
176 		if (ret)
177 			return ret;
178 
179 		if (m == IIO_CHAN_INFO_RAW)
180 			return IIO_VAL_INT;
181 
182 		/* storm out of range */
183 		if (*val == AS3935_DATA_MASK)
184 			return -EINVAL;
185 
186 		if (m == IIO_CHAN_INFO_PROCESSED)
187 			*val *= 1000;
188 		break;
189 	case IIO_CHAN_INFO_SCALE:
190 		*val = 1000;
191 		break;
192 	default:
193 		return -EINVAL;
194 	}
195 
196 	return IIO_VAL_INT;
197 }
198 
199 static const struct iio_info as3935_info = {
200 	.driver_module = THIS_MODULE,
201 	.attrs = &as3935_attribute_group,
202 	.read_raw = &as3935_read_raw,
203 };
204 
205 static irqreturn_t as3935_trigger_handler(int irq, void *private)
206 {
207 	struct iio_poll_func *pf = private;
208 	struct iio_dev *indio_dev = pf->indio_dev;
209 	struct as3935_state *st = iio_priv(indio_dev);
210 	int val, ret;
211 
212 	ret = as3935_read(st, AS3935_DATA, &val);
213 	if (ret)
214 		goto err_read;
215 
216 	st->buffer[0] = val & AS3935_DATA_MASK;
217 	iio_push_to_buffers_with_timestamp(indio_dev, &st->buffer,
218 					   pf->timestamp);
219 err_read:
220 	iio_trigger_notify_done(indio_dev->trig);
221 
222 	return IRQ_HANDLED;
223 }
224 
225 static const struct iio_trigger_ops iio_interrupt_trigger_ops = {
226 	.owner = THIS_MODULE,
227 };
228 
229 static void as3935_event_work(struct work_struct *work)
230 {
231 	struct as3935_state *st;
232 	int val;
233 	int ret;
234 
235 	st = container_of(work, struct as3935_state, work.work);
236 
237 	ret = as3935_read(st, AS3935_INT, &val);
238 	if (ret) {
239 		dev_warn(&st->spi->dev, "read error\n");
240 		return;
241 	}
242 
243 	val &= AS3935_INT_MASK;
244 
245 	switch (val) {
246 	case AS3935_EVENT_INT:
247 		iio_trigger_poll(st->trig);
248 		break;
249 	case AS3935_NOISE_INT:
250 		dev_warn(&st->spi->dev, "noise level is too high\n");
251 		break;
252 	}
253 }
254 
255 static irqreturn_t as3935_interrupt_handler(int irq, void *private)
256 {
257 	struct iio_dev *indio_dev = private;
258 	struct as3935_state *st = iio_priv(indio_dev);
259 
260 	/*
261 	 * Delay work for >2 milliseconds after an interrupt to allow
262 	 * estimated distance to recalculated.
263 	 */
264 
265 	schedule_delayed_work(&st->work, msecs_to_jiffies(3));
266 
267 	return IRQ_HANDLED;
268 }
269 
270 static void calibrate_as3935(struct as3935_state *st)
271 {
272 	mutex_lock(&st->lock);
273 
274 	/* mask disturber interrupt bit */
275 	as3935_write(st, AS3935_INT, BIT(5));
276 
277 	as3935_write(st, AS3935_CALIBRATE, 0x96);
278 	as3935_write(st, AS3935_TUNE_CAP,
279 		BIT(5) | (st->tune_cap / TUNE_CAP_DIV));
280 
281 	mdelay(2);
282 	as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV));
283 
284 	mutex_unlock(&st->lock);
285 }
286 
287 #ifdef CONFIG_PM_SLEEP
288 static int as3935_suspend(struct device *dev)
289 {
290 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
291 	struct as3935_state *st = iio_priv(indio_dev);
292 	int val, ret;
293 
294 	mutex_lock(&st->lock);
295 	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
296 	if (ret)
297 		goto err_suspend;
298 	val |= AS3935_AFE_PWR_BIT;
299 
300 	ret = as3935_write(st, AS3935_AFE_GAIN, val);
301 
302 err_suspend:
303 	mutex_unlock(&st->lock);
304 
305 	return ret;
306 }
307 
308 static int as3935_resume(struct device *dev)
309 {
310 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
311 	struct as3935_state *st = iio_priv(indio_dev);
312 	int val, ret;
313 
314 	mutex_lock(&st->lock);
315 	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
316 	if (ret)
317 		goto err_resume;
318 	val &= ~AS3935_AFE_PWR_BIT;
319 	ret = as3935_write(st, AS3935_AFE_GAIN, val);
320 
321 err_resume:
322 	mutex_unlock(&st->lock);
323 
324 	return ret;
325 }
326 
327 static SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
328 #define AS3935_PM_OPS (&as3935_pm_ops)
329 
330 #else
331 #define AS3935_PM_OPS NULL
332 #endif
333 
334 static int as3935_probe(struct spi_device *spi)
335 {
336 	struct iio_dev *indio_dev;
337 	struct iio_trigger *trig;
338 	struct as3935_state *st;
339 	struct device_node *np = spi->dev.of_node;
340 	int ret;
341 
342 	/* Be sure lightning event interrupt is specified */
343 	if (!spi->irq) {
344 		dev_err(&spi->dev, "unable to get event interrupt\n");
345 		return -EINVAL;
346 	}
347 
348 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
349 	if (!indio_dev)
350 		return -ENOMEM;
351 
352 	st = iio_priv(indio_dev);
353 	st->spi = spi;
354 
355 	spi_set_drvdata(spi, indio_dev);
356 	mutex_init(&st->lock);
357 	INIT_DELAYED_WORK(&st->work, as3935_event_work);
358 
359 	ret = of_property_read_u32(np,
360 			"ams,tuning-capacitor-pf", &st->tune_cap);
361 	if (ret) {
362 		st->tune_cap = 0;
363 		dev_warn(&spi->dev,
364 			"no tuning-capacitor-pf set, defaulting to %d",
365 			st->tune_cap);
366 	}
367 
368 	if (st->tune_cap > MAX_PF_CAP) {
369 		dev_err(&spi->dev,
370 			"wrong tuning-capacitor-pf setting of %d\n",
371 			st->tune_cap);
372 		return -EINVAL;
373 	}
374 
375 	indio_dev->dev.parent = &spi->dev;
376 	indio_dev->name = spi_get_device_id(spi)->name;
377 	indio_dev->channels = as3935_channels;
378 	indio_dev->num_channels = ARRAY_SIZE(as3935_channels);
379 	indio_dev->modes = INDIO_DIRECT_MODE;
380 	indio_dev->info = &as3935_info;
381 
382 	trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d",
383 				      indio_dev->name, indio_dev->id);
384 
385 	if (!trig)
386 		return -ENOMEM;
387 
388 	st->trig = trig;
389 	trig->dev.parent = indio_dev->dev.parent;
390 	iio_trigger_set_drvdata(trig, indio_dev);
391 	trig->ops = &iio_interrupt_trigger_ops;
392 
393 	ret = iio_trigger_register(trig);
394 	if (ret) {
395 		dev_err(&spi->dev, "failed to register trigger\n");
396 		return ret;
397 	}
398 
399 	ret = iio_triggered_buffer_setup(indio_dev, iio_pollfunc_store_time,
400 		&as3935_trigger_handler, NULL);
401 
402 	if (ret) {
403 		dev_err(&spi->dev, "cannot setup iio trigger\n");
404 		goto unregister_trigger;
405 	}
406 
407 	calibrate_as3935(st);
408 
409 	ret = devm_request_irq(&spi->dev, spi->irq,
410 				&as3935_interrupt_handler,
411 				IRQF_TRIGGER_RISING,
412 				dev_name(&spi->dev),
413 				indio_dev);
414 
415 	if (ret) {
416 		dev_err(&spi->dev, "unable to request irq\n");
417 		goto unregister_buffer;
418 	}
419 
420 	ret = iio_device_register(indio_dev);
421 	if (ret < 0) {
422 		dev_err(&spi->dev, "unable to register device\n");
423 		goto unregister_buffer;
424 	}
425 	return 0;
426 
427 unregister_buffer:
428 	iio_triggered_buffer_cleanup(indio_dev);
429 
430 unregister_trigger:
431 	iio_trigger_unregister(st->trig);
432 
433 	return ret;
434 }
435 
436 static int as3935_remove(struct spi_device *spi)
437 {
438 	struct iio_dev *indio_dev = spi_get_drvdata(spi);
439 	struct as3935_state *st = iio_priv(indio_dev);
440 
441 	iio_device_unregister(indio_dev);
442 	iio_triggered_buffer_cleanup(indio_dev);
443 	iio_trigger_unregister(st->trig);
444 
445 	return 0;
446 }
447 
448 static const struct of_device_id as3935_of_match[] = {
449 	{ .compatible = "ams,as3935", },
450 	{ /* sentinel */ },
451 };
452 MODULE_DEVICE_TABLE(of, as3935_of_match);
453 
454 static const struct spi_device_id as3935_id[] = {
455 	{"as3935", 0},
456 	{},
457 };
458 MODULE_DEVICE_TABLE(spi, as3935_id);
459 
460 static struct spi_driver as3935_driver = {
461 	.driver = {
462 		.name	= "as3935",
463 		.of_match_table = of_match_ptr(as3935_of_match),
464 		.pm	= AS3935_PM_OPS,
465 	},
466 	.probe		= as3935_probe,
467 	.remove		= as3935_remove,
468 	.id_table	= as3935_id,
469 };
470 module_spi_driver(as3935_driver);
471 
472 MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
473 MODULE_DESCRIPTION("AS3935 lightning sensor");
474 MODULE_LICENSE("GPL");
475