[deliverable/linux.git] / drivers / iio / humidity / dht11.c

/*
 * DHT11/DHT22 bit banging GPIO driver
 *
 * Copyright (c) Harald Geyer <harald@ccbib.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 */

#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/sysfs.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/wait.h>
#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/timekeeping.h>

#include <linux/iio/iio.h>

#define DRIVER_NAME	"dht11"

#define DHT11_DATA_VALID_TIME	2000000000  /* 2s in ns */

#define DHT11_EDGES_PREAMBLE 2
#define DHT11_BITS_PER_READ 40
/*
 * Note that when reading the sensor actually 84 edges are detected, but
 * since the last edge is not significant, we only store 83:
 */
#define DHT11_EDGES_PER_READ (2 * DHT11_BITS_PER_READ + \
			      DHT11_EDGES_PREAMBLE + 1)

/*
 * Data transmission timing:
 * Data bits are encoded as pulse length (high time) on the data line.
 * 0-bit: 22-30uS -- typically 26uS (AM2302)
 * 1-bit: 68-75uS -- typically 70uS (AM2302)
 * The acutal timings also depend on the properties of the cable, with
 * longer cables typically making pulses shorter.
 *
 * Our decoding depends on the time resolution of the system:
 * timeres > 34uS ... don't know what a 1-tick pulse is
 * 34uS > timeres > 30uS ... no problem (30kHz and 32kHz clocks)
 * 30uS > timeres > 23uS ... don't know what a 2-tick pulse is
 * timeres < 23uS ... no problem
 *
 * Luckily clocks in the 33-44kHz range are quite uncommon, so we can
 * support most systems if the threshold for decoding a pulse as 1-bit
 * is chosen carefully. If somebody really wants to support clocks around
 * 40kHz, where this driver is most unreliable, there are two options.
 * a) select an implementation using busy loop polling on those systems
 * b) use the checksum to do some probabilistic decoding
 */
#define DHT11_START_TRANSMISSION	18  /* ms */
#define DHT11_MIN_TIMERES	34000  /* ns */
#define DHT11_THRESHOLD		49000  /* ns */
#define DHT11_AMBIG_LOW		23000  /* ns */
#define DHT11_AMBIG_HIGH	30000  /* ns */

struct dht11 {
	struct device			*dev;

	int				gpio;
	int				irq;

	struct completion		completion;
	/* The iio sysfs interface doesn't prevent concurrent reads: */
	struct mutex			lock;

	s64				timestamp;
	int				temperature;
	int				humidity;

	/* num_edges: -1 means "no transmission in progress" */
	int				num_edges;
	struct {s64 ts; int value; }	edges[DHT11_EDGES_PER_READ];
};

#ifdef CONFIG_DYNAMIC_DEBUG
/*
 * dht11_edges_print: show the data as actually received by the
 *                    driver.
 */
static void dht11_edges_print(struct dht11 *dht11)
{
	int i;

	dev_dbg(dht11->dev, "%d edges detected:\n", dht11->num_edges);
	for (i = 1; i < dht11->num_edges; ++i) {
		dev_dbg(dht11->dev, "%d: %lld ns %s\n", i,
			dht11->edges[i].ts - dht11->edges[i - 1].ts,
			dht11->edges[i - 1].value ? "high" : "low");
	}
}
#endif /* CONFIG_DYNAMIC_DEBUG */

static unsigned char dht11_decode_byte(char *bits)
{
	unsigned char ret = 0;
	int i;

	for (i = 0; i < 8; ++i) {
		ret <<= 1;
		if (bits[i])
			++ret;
	}

	return ret;
}

static int dht11_decode(struct dht11 *dht11, int offset)
{
	int i, t;
	char bits[DHT11_BITS_PER_READ];
	unsigned char temp_int, temp_dec, hum_int, hum_dec, checksum;

	for (i = 0; i < DHT11_BITS_PER_READ; ++i) {
		t = dht11->edges[offset + 2 * i + 2].ts -
			dht11->edges[offset + 2 * i + 1].ts;
		if (!dht11->edges[offset + 2 * i + 1].value) {
			dev_dbg(dht11->dev,
				"lost synchronisation at edge %d\n",
				offset + 2 * i + 1);
			return -EIO;
		}
		bits[i] = t > DHT11_THRESHOLD;
	}

	hum_int = dht11_decode_byte(bits);
	hum_dec = dht11_decode_byte(&bits[8]);
	temp_int = dht11_decode_byte(&bits[16]);
	temp_dec = dht11_decode_byte(&bits[24]);
	checksum = dht11_decode_byte(&bits[32]);

	if (((hum_int + hum_dec + temp_int + temp_dec) & 0xff) != checksum) {
		dev_dbg(dht11->dev, "invalid checksum\n");
		return -EIO;
	}

	dht11->timestamp = ktime_get_boot_ns();
	if (hum_int < 20) {  /* DHT22 */
		dht11->temperature = (((temp_int & 0x7f) << 8) + temp_dec) *
					((temp_int & 0x80) ? -100 : 100);
		dht11->humidity = ((hum_int << 8) + hum_dec) * 100;
	} else if (temp_dec == 0 && hum_dec == 0) {  /* DHT11 */
		dht11->temperature = temp_int * 1000;
		dht11->humidity = hum_int * 1000;
	} else {
		dev_err(dht11->dev,
			"Don't know how to decode data: %d %d %d %d\n",
			hum_int, hum_dec, temp_int, temp_dec);
		return -EIO;
	}

	return 0;
}

/*
 * IRQ handler called on GPIO edges
 */
static irqreturn_t dht11_handle_irq(int irq, void *data)
{
	struct iio_dev *iio = data;
	struct dht11 *dht11 = iio_priv(iio);

	/* TODO: Consider making the handler safe for IRQ sharing */
	if (dht11->num_edges < DHT11_EDGES_PER_READ && dht11->num_edges >= 0) {
		dht11->edges[dht11->num_edges].ts = ktime_get_boot_ns();
		dht11->edges[dht11->num_edges++].value =
						gpio_get_value(dht11->gpio);

		if (dht11->num_edges >= DHT11_EDGES_PER_READ)
			complete(&dht11->completion);
	}

	return IRQ_HANDLED;
}

static int dht11_read_raw(struct iio_dev *iio_dev,
			  const struct iio_chan_spec *chan,
			int *val, int *val2, long m)
{
	struct dht11 *dht11 = iio_priv(iio_dev);
	int ret, timeres, offset;

	mutex_lock(&dht11->lock);
	if (dht11->timestamp + DHT11_DATA_VALID_TIME < ktime_get_boot_ns()) {
		timeres = ktime_get_resolution_ns();
		dev_dbg(dht11->dev, "current timeresolution: %dns\n", timeres);
		if (timeres > DHT11_MIN_TIMERES) {
			dev_err(dht11->dev, "timeresolution %dns too low\n",
				timeres);
			/* In theory a better clock could become available
			 * at some point ... and there is no error code
			 * that really fits better.
			 */
			ret = -EAGAIN;
			goto err;
		}
		if (timeres > DHT11_AMBIG_LOW && timeres < DHT11_AMBIG_HIGH)
			dev_warn(dht11->dev,
				 "timeresolution: %dns - decoding ambiguous\n",
				 timeres);

		reinit_completion(&dht11->completion);

		dht11->num_edges = 0;
		ret = gpio_direction_output(dht11->gpio, 0);
		if (ret)
			goto err;
		msleep(DHT11_START_TRANSMISSION);
		ret = gpio_direction_input(dht11->gpio);
		if (ret)
			goto err;

		ret = request_irq(dht11->irq, dht11_handle_irq,
				  IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
				  iio_dev->name, iio_dev);
		if (ret)
			goto err;

		ret = wait_for_completion_killable_timeout(&dht11->completion,
							   HZ);

		free_irq(dht11->irq, iio_dev);

#ifdef CONFIG_DYNAMIC_DEBUG
		dht11_edges_print(dht11);
#endif

		if (ret == 0 && dht11->num_edges < DHT11_EDGES_PER_READ - 1) {
			dev_err(dht11->dev, "Only %d signal edges detected\n",
				dht11->num_edges);
			ret = -ETIMEDOUT;
		}
		if (ret < 0)
			goto err;

		offset = DHT11_EDGES_PREAMBLE +
				dht11->num_edges - DHT11_EDGES_PER_READ;
		for (; offset >= 0; --offset) {
			ret = dht11_decode(dht11, offset);
			if (!ret)
				break;
		}

		if (ret)
			goto err;
	}

	ret = IIO_VAL_INT;
	if (chan->type == IIO_TEMP)
		*val = dht11->temperature;
	else if (chan->type == IIO_HUMIDITYRELATIVE)
		*val = dht11->humidity;
	else
		ret = -EINVAL;
err:
	dht11->num_edges = -1;
	mutex_unlock(&dht11->lock);
	return ret;
}

static const struct iio_info dht11_iio_info = {
	.driver_module		= THIS_MODULE,
	.read_raw		= dht11_read_raw,
};

static const struct iio_chan_spec dht11_chan_spec[] = {
	{ .type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), },
	{ .type = IIO_HUMIDITYRELATIVE,
		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), }
};

static const struct of_device_id dht11_dt_ids[] = {
	{ .compatible = "dht11", },
	{ }
};
MODULE_DEVICE_TABLE(of, dht11_dt_ids);

static int dht11_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct device_node *node = dev->of_node;
	struct dht11 *dht11;
	struct iio_dev *iio;
	int ret;

	iio = devm_iio_device_alloc(dev, sizeof(*dht11));
	if (!iio) {
		dev_err(dev, "Failed to allocate IIO device\n");
		return -ENOMEM;
	}

	dht11 = iio_priv(iio);
	dht11->dev = dev;

	ret = of_get_gpio(node, 0);
	if (ret < 0)
		return ret;
	dht11->gpio = ret;
	ret = devm_gpio_request_one(dev, dht11->gpio, GPIOF_IN, pdev->name);
	if (ret)
		return ret;

	dht11->irq = gpio_to_irq(dht11->gpio);
	if (dht11->irq < 0) {
		dev_err(dev, "GPIO %d has no interrupt\n", dht11->gpio);
		return -EINVAL;
	}

	dht11->timestamp = ktime_get_boot_ns() - DHT11_DATA_VALID_TIME - 1;
	dht11->num_edges = -1;

	platform_set_drvdata(pdev, iio);

	init_completion(&dht11->completion);
	mutex_init(&dht11->lock);
	iio->name = pdev->name;
	iio->dev.parent = &pdev->dev;
	iio->info = &dht11_iio_info;
	iio->modes = INDIO_DIRECT_MODE;
	iio->channels = dht11_chan_spec;
	iio->num_channels = ARRAY_SIZE(dht11_chan_spec);

	return devm_iio_device_register(dev, iio);
}

static struct platform_driver dht11_driver = {
	.driver = {
		.name	= DRIVER_NAME,
		.of_match_table = dht11_dt_ids,
	},
	.probe  = dht11_probe,
};

module_platform_driver(dht11_driver);

MODULE_AUTHOR("Harald Geyer <harald@ccbib.org>");
MODULE_DESCRIPTION("DHT11 humidity/temperature sensor driver");
MODULE_LICENSE("GPL v2");
Commit	Line	Data
091a121b HG	1	/*
	2	* DHT11/DHT22 bit banging GPIO driver
	3	*
	4	* Copyright (c) Harald Geyer <harald@ccbib.org>
	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	#include <linux/err.h>
	18	#include <linux/interrupt.h>
	19	#include <linux/device.h>
	20	#include <linux/kernel.h>
	21	#include <linux/printk.h>
	22	#include <linux/slab.h>
	23	#include <linux/of.h>
	24	#include <linux/of_device.h>
	25	#include <linux/sysfs.h>
	26	#include <linux/io.h>
	27	#include <linux/module.h>
	28	#include <linux/platform_device.h>
	29	#include <linux/wait.h>
	30	#include <linux/bitops.h>
	31	#include <linux/completion.h>
004bc530	32	#include <linux/mutex.h>
091a121b HG	33	#include <linux/delay.h>
	34	#include <linux/gpio.h>
	35	#include <linux/of_gpio.h>
081d9740	36	#include <linux/timekeeping.h>
091a121b HG	37
	38	#include <linux/iio/iio.h>
	39
	40	#define DRIVER_NAME "dht11"
	41
	42	#define DHT11_DATA_VALID_TIME 2000000000 /* 2s in ns */
	43
94e65519	44	#define DHT11_EDGES_PREAMBLE 2
091a121b	45	#define DHT11_BITS_PER_READ 40
94e65519 RW	46	/*
	47	* Note that when reading the sensor actually 84 edges are detected, but
	48	* since the last edge is not significant, we only store 83:
	49	*/
889c5e9b HG	50	#define DHT11_EDGES_PER_READ (2 * DHT11_BITS_PER_READ + \
889c5e9b HG	51	DHT11_EDGES_PREAMBLE + 1)
091a121b	52
155a5759 HG	53	/*
	54	* Data transmission timing:
	55	* Data bits are encoded as pulse length (high time) on the data line.
	56	* 0-bit: 22-30uS -- typically 26uS (AM2302)
	57	* 1-bit: 68-75uS -- typically 70uS (AM2302)
	58	* The acutal timings also depend on the properties of the cable, with
	59	* longer cables typically making pulses shorter.
	60	*
	61	* Our decoding depends on the time resolution of the system:
	62	* timeres > 34uS ... don't know what a 1-tick pulse is
	63	* 34uS > timeres > 30uS ... no problem (30kHz and 32kHz clocks)
	64	* 30uS > timeres > 23uS ... don't know what a 2-tick pulse is
	65	* timeres < 23uS ... no problem
	66	*
	67	* Luckily clocks in the 33-44kHz range are quite uncommon, so we can
	68	* support most systems if the threshold for decoding a pulse as 1-bit
	69	* is chosen carefully. If somebody really wants to support clocks around
	70	* 40kHz, where this driver is most unreliable, there are two options.
	71	* a) select an implementation using busy loop polling on those systems
	72	* b) use the checksum to do some probabilistic decoding
	73	*/
091a121b	74	#define DHT11_START_TRANSMISSION 18 /* ms */
155a5759 HG	75	#define DHT11_MIN_TIMERES 34000 /* ns */
	76	#define DHT11_THRESHOLD 49000 /* ns */
	77	#define DHT11_AMBIG_LOW 23000 /* ns */
	78	#define DHT11_AMBIG_HIGH 30000 /* ns */
091a121b HG	79
	80	struct dht11 {
	81	struct device *dev;
	82
	83	int gpio;
	84	int irq;
	85
	86	struct completion completion;
a7126003	87	/* The iio sysfs interface doesn't prevent concurrent reads: */
004bc530	88	struct mutex lock;
091a121b HG	89
	90	s64 timestamp;
	91	int temperature;
	92	int humidity;
	93
	94	/* num_edges: -1 means "no transmission in progress" */
	95	int num_edges;
	96	struct {s64 ts; int value; } edges[DHT11_EDGES_PER_READ];
	97	};
	98
ab4b6496 HG	99	#ifdef CONFIG_DYNAMIC_DEBUG
	100	/*
	101	* dht11_edges_print: show the data as actually received by the
	102	* driver.
	103	*/
	104	static void dht11_edges_print(struct dht11 *dht11)
	105	{
	106	int i;
	107
	108	dev_dbg(dht11->dev, "%d edges detected:\n", dht11->num_edges);
	109	for (i = 1; i < dht11->num_edges; ++i) {
	110	dev_dbg(dht11->dev, "%d: %lld ns %s\n", i,
	111	dht11->edges[i].ts - dht11->edges[i - 1].ts,
	112	dht11->edges[i - 1].value ? "high" : "low");
	113	}
	114	}
	115	#endif /* CONFIG_DYNAMIC_DEBUG */
	116
155a5759	117	static unsigned char dht11_decode_byte(char *bits)
091a121b HG	118	{
	119	unsigned char ret = 0;
	120	int i;
	121
	122	for (i = 0; i < 8; ++i) {
	123	ret <<= 1;
155a5759	124	if (bits[i])
091a121b HG	125	++ret;
	126	}
	127
	128	return ret;
	129	}
	130
155a5759	131	static int dht11_decode(struct dht11 *dht11, int offset)
091a121b	132	{
155a5759 HG	133	int i, t;
155a5759 HG	134	char bits[DHT11_BITS_PER_READ];
091a121b HG	135	unsigned char temp_int, temp_dec, hum_int, hum_dec, checksum;
091a121b HG	136
091a121b	137	for (i = 0; i < DHT11_BITS_PER_READ; ++i) {
889c5e9b HG	138	t = dht11->edges[offset + 2 * i + 2].ts -
889c5e9b HG	139	dht11->edges[offset + 2 * i + 1].ts;
ab4b6496 HG	140	if (!dht11->edges[offset + 2 * i + 1].value) {
	141	dev_dbg(dht11->dev,
	142	"lost synchronisation at edge %d\n",
	143	offset + 2 * i + 1);
	144	return -EIO;
	145	}
155a5759	146	bits[i] = t > DHT11_THRESHOLD;
091a121b HG	147	}
091a121b HG	148
155a5759 HG	149	hum_int = dht11_decode_byte(bits);
	150	hum_dec = dht11_decode_byte(&bits[8]);
	151	temp_int = dht11_decode_byte(&bits[16]);
	152	temp_dec = dht11_decode_byte(&bits[24]);
	153	checksum = dht11_decode_byte(&bits[32]);
091a121b	154
ab4b6496 HG	155	if (((hum_int + hum_dec + temp_int + temp_dec) & 0xff) != checksum) {
ab4b6496 HG	156	dev_dbg(dht11->dev, "invalid checksum\n");
091a121b	157	return -EIO;
ab4b6496	158	}
091a121b	159
17a2f46c	160	dht11->timestamp = ktime_get_boot_ns();
091a121b HG	161	if (hum_int < 20) { /* DHT22 */
	162	dht11->temperature = (((temp_int & 0x7f) << 8) + temp_dec) *
	163	((temp_int & 0x80) ? -100 : 100);
	164	dht11->humidity = ((hum_int << 8) + hum_dec) * 100;
	165	} else if (temp_dec == 0 && hum_dec == 0) { /* DHT11 */
	166	dht11->temperature = temp_int * 1000;
	167	dht11->humidity = hum_int * 1000;
	168	} else {
	169	dev_err(dht11->dev,
	170	"Don't know how to decode data: %d %d %d %d\n",
	171	hum_int, hum_dec, temp_int, temp_dec);
	172	return -EIO;
	173	}
	174
	175	return 0;
	176	}
	177
94e65519 RW	178	/*
	179	* IRQ handler called on GPIO edges
	180	*/
	181	static irqreturn_t dht11_handle_irq(int irq, void *data)
	182	{
	183	struct iio_dev *iio = data;
	184	struct dht11 *dht11 = iio_priv(iio);
	185
	186	/* TODO: Consider making the handler safe for IRQ sharing */
	187	if (dht11->num_edges < DHT11_EDGES_PER_READ && dht11->num_edges >= 0) {
17a2f46c	188	dht11->edges[dht11->num_edges].ts = ktime_get_boot_ns();
94e65519 RW	189	dht11->edges[dht11->num_edges++].value =
	190	gpio_get_value(dht11->gpio);
	191
	192	if (dht11->num_edges >= DHT11_EDGES_PER_READ)
	193	complete(&dht11->completion);
	194	}
	195
	196	return IRQ_HANDLED;
	197	}
	198
091a121b	199	static int dht11_read_raw(struct iio_dev *iio_dev,
889c5e9b	200	const struct iio_chan_spec *chan,
091a121b HG	201	int val, int val2, long m)
	202	{
	203	struct dht11 *dht11 = iio_priv(iio_dev);
22acc120	204	int ret, timeres, offset;
091a121b	205
004bc530	206	mutex_lock(&dht11->lock);
17a2f46c	207	if (dht11->timestamp + DHT11_DATA_VALID_TIME < ktime_get_boot_ns()) {
081d9740	208	timeres = ktime_get_resolution_ns();
ab4b6496	209	dev_dbg(dht11->dev, "current timeresolution: %dns\n", timeres);
155a5759	210	if (timeres > DHT11_MIN_TIMERES) {
081d9740 HG	211	dev_err(dht11->dev, "timeresolution %dns too low\n",
	212	timeres);
	213	/* In theory a better clock could become available
	214	* at some point ... and there is no error code
	215	* that really fits better.
	216	*/
	217	ret = -EAGAIN;
	218	goto err;
	219	}
155a5759 HG	220	if (timeres > DHT11_AMBIG_LOW && timeres < DHT11_AMBIG_HIGH)
	221	dev_warn(dht11->dev,
	222	"timeresolution: %dns - decoding ambiguous\n",
	223	timeres);
081d9740	224
091a121b HG	225	reinit_completion(&dht11->completion);
	226
	227	dht11->num_edges = 0;
	228	ret = gpio_direction_output(dht11->gpio, 0);
	229	if (ret)
	230	goto err;
	231	msleep(DHT11_START_TRANSMISSION);
	232	ret = gpio_direction_input(dht11->gpio);
	233	if (ret)
	234	goto err;
	235
94e65519 RW	236	ret = request_irq(dht11->irq, dht11_handle_irq,
	237	IRQF_TRIGGER_RISING \| IRQF_TRIGGER_FALLING,
	238	iio_dev->name, iio_dev);
	239	if (ret)
	240	goto err;
	241
091a121b	242	ret = wait_for_completion_killable_timeout(&dht11->completion,
889c5e9b	243	HZ);
94e65519 RW	244
	245	free_irq(dht11->irq, iio_dev);
	246
ab4b6496 HG	247	#ifdef CONFIG_DYNAMIC_DEBUG
	248	dht11_edges_print(dht11);
	249	#endif
	250
091a121b	251	if (ret == 0 && dht11->num_edges < DHT11_EDGES_PER_READ - 1) {
ab4b6496 HG	252	dev_err(dht11->dev, "Only %d signal edges detected\n",
ab4b6496 HG	253	dht11->num_edges);
091a121b HG	254	ret = -ETIMEDOUT;
	255	}
	256	if (ret < 0)
	257	goto err;
	258
22acc120 HG	259	offset = DHT11_EDGES_PREAMBLE +
	260	dht11->num_edges - DHT11_EDGES_PER_READ;
	261	for (; offset >= 0; --offset) {
155a5759	262	ret = dht11_decode(dht11, offset);
22acc120 HG	263	if (!ret)
	264	break;
	265	}
	266
091a121b HG	267	if (ret)
	268	goto err;
	269	}
	270
	271	ret = IIO_VAL_INT;
	272	if (chan->type == IIO_TEMP)
	273	*val = dht11->temperature;
	274	else if (chan->type == IIO_HUMIDITYRELATIVE)
	275	*val = dht11->humidity;
	276	else
	277	ret = -EINVAL;
	278	err:
	279	dht11->num_edges = -1;
004bc530	280	mutex_unlock(&dht11->lock);
091a121b HG	281	return ret;
	282	}
	283
	284	static const struct iio_info dht11_iio_info = {
	285	.driver_module = THIS_MODULE,
	286	.read_raw = dht11_read_raw,
	287	};
	288
091a121b HG	289	static const struct iio_chan_spec dht11_chan_spec[] = {
	290	{ .type = IIO_TEMP,
	291	.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), },
	292	{ .type = IIO_HUMIDITYRELATIVE,
	293	.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), }
	294	};
	295
	296	static const struct of_device_id dht11_dt_ids[] = {
	297	{ .compatible = "dht11", },
	298	{ }
	299	};
	300	MODULE_DEVICE_TABLE(of, dht11_dt_ids);
	301
	302	static int dht11_probe(struct platform_device *pdev)
	303	{
	304	struct device *dev = &pdev->dev;
	305	struct device_node *node = dev->of_node;
	306	struct dht11 *dht11;
	307	struct iio_dev *iio;
	308	int ret;
	309
	310	iio = devm_iio_device_alloc(dev, sizeof(*dht11));
	311	if (!iio) {
	312	dev_err(dev, "Failed to allocate IIO device\n");
	313	return -ENOMEM;
	314	}
	315
	316	dht11 = iio_priv(iio);
	317	dht11->dev = dev;
	318
5fbb0bc4	319	ret = of_get_gpio(node, 0);
091a121b HG	320	if (ret < 0)
091a121b HG	321	return ret;
5fbb0bc4	322	dht11->gpio = ret;
091a121b HG	323	ret = devm_gpio_request_one(dev, dht11->gpio, GPIOF_IN, pdev->name);
	324	if (ret)
	325	return ret;
	326
	327	dht11->irq = gpio_to_irq(dht11->gpio);
	328	if (dht11->irq < 0) {
	329	dev_err(dev, "GPIO %d has no interrupt\n", dht11->gpio);
	330	return -EINVAL;
	331	}
091a121b	332
17a2f46c	333	dht11->timestamp = ktime_get_boot_ns() - DHT11_DATA_VALID_TIME - 1;
091a121b HG	334	dht11->num_edges = -1;
	335
	336	platform_set_drvdata(pdev, iio);
	337
	338	init_completion(&dht11->completion);
004bc530	339	mutex_init(&dht11->lock);
091a121b HG	340	iio->name = pdev->name;
	341	iio->dev.parent = &pdev->dev;
	342	iio->info = &dht11_iio_info;
	343	iio->modes = INDIO_DIRECT_MODE;
	344	iio->channels = dht11_chan_spec;
	345	iio->num_channels = ARRAY_SIZE(dht11_chan_spec);
	346
	347	return devm_iio_device_register(dev, iio);
	348	}
	349
	350	static struct platform_driver dht11_driver = {
	351	.driver = {
	352	.name = DRIVER_NAME,
091a121b HG	353	.of_match_table = dht11_dt_ids,
	354	},
	355	.probe = dht11_probe,
	356	};
	357
	358	module_platform_driver(dht11_driver);
	359
	360	MODULE_AUTHOR("Harald Geyer <harald@ccbib.org>");
	361	MODULE_DESCRIPTION("DHT11 humidity/temperature sensor driver");
	362	MODULE_LICENSE("GPL v2");