[linux-2.6-block.git] / drivers / iio / proximity / srf04.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * SRF04: ultrasonic sensor for distance measuring by using GPIOs
 *
 * Copyright (c) 2017 Andreas Klinger <ak@it-klinger.de>
 *
 * For details about the device see:
 * http://www.robot-electronics.co.uk/htm/srf04tech.htm
 *
 * the measurement cycle as timing diagram looks like:
 *
 *          +---+
 * GPIO     |   |
 * trig:  --+   +------------------------------------------------------
 *          ^   ^
 *          |<->|
 *         udelay(trigger_pulse_us)
 *
 * ultra           +-+ +-+ +-+
 * sonic           | | | | | |
 * burst: ---------+ +-+ +-+ +-----------------------------------------
 *                           .
 * ultra                     .              +-+ +-+ +-+
 * sonic                     .              | | | | | |
 * echo:  ----------------------------------+ +-+ +-+ +----------------
 *                           .                        .
 *                           +------------------------+
 * GPIO                      |                        |
 * echo:  -------------------+                        +---------------
 *                           ^                        ^
 *                           interrupt                interrupt
 *                           (ts_rising)              (ts_falling)
 *                           |<---------------------->|
 *                              pulse time measured
 *                              --> one round trip of ultra sonic waves
 */
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>

struct srf04_cfg {
	unsigned long trigger_pulse_us;
};

struct srf04_data {
	struct device		*dev;
	struct gpio_desc	*gpiod_trig;
	struct gpio_desc	*gpiod_echo;
	struct mutex		lock;
	int			irqnr;
	ktime_t			ts_rising;
	ktime_t			ts_falling;
	struct completion	rising;
	struct completion	falling;
	const struct srf04_cfg	*cfg;
};

static const struct srf04_cfg srf04_cfg = {
	.trigger_pulse_us = 10,
};

static const struct srf04_cfg mb_lv_cfg = {
	.trigger_pulse_us = 20,
};

static irqreturn_t srf04_handle_irq(int irq, void *dev_id)
{
	struct iio_dev *indio_dev = dev_id;
	struct srf04_data *data = iio_priv(indio_dev);
	ktime_t now = ktime_get();

	if (gpiod_get_value(data->gpiod_echo)) {
		data->ts_rising = now;
		complete(&data->rising);
	} else {
		data->ts_falling = now;
		complete(&data->falling);
	}

	return IRQ_HANDLED;
}

static int srf04_read(struct srf04_data *data)
{
	int ret;
	ktime_t ktime_dt;
	u64 dt_ns;
	u32 time_ns, distance_mm;

	/*
	 * just one read-echo-cycle can take place at a time
	 * ==> lock against concurrent reading calls
	 */
	mutex_lock(&data->lock);

	reinit_completion(&data->rising);
	reinit_completion(&data->falling);

	gpiod_set_value(data->gpiod_trig, 1);
	udelay(data->cfg->trigger_pulse_us);
	gpiod_set_value(data->gpiod_trig, 0);

	/* it cannot take more than 20 ms */
	ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);
	if (ret < 0) {
		mutex_unlock(&data->lock);
		return ret;
	} else if (ret == 0) {
		mutex_unlock(&data->lock);
		return -ETIMEDOUT;
	}

	ret = wait_for_completion_killable_timeout(&data->falling, HZ/50);
	if (ret < 0) {
		mutex_unlock(&data->lock);
		return ret;
	} else if (ret == 0) {
		mutex_unlock(&data->lock);
		return -ETIMEDOUT;
	}

	ktime_dt = ktime_sub(data->ts_falling, data->ts_rising);

	mutex_unlock(&data->lock);

	dt_ns = ktime_to_ns(ktime_dt);
	/*
	 * measuring more than 3 meters is beyond the capabilities of
	 * the sensor
	 * ==> filter out invalid results for not measuring echos of
	 *     another us sensor
	 *
	 * formula:
	 *         distance       3 m
	 * time = ---------- = --------- = 9404389 ns
	 *          speed       319 m/s
	 *
	 * using a minimum speed at -20 °C of 319 m/s
	 */
	if (dt_ns > 9404389)
		return -EIO;

	time_ns = dt_ns;

	/*
	 * the speed as function of the temperature is approximately:
	 *
	 * speed = 331,5 + 0,6 * Temp
	 *   with Temp in °C
	 *   and speed in m/s
	 *
	 * use 343 m/s as ultrasonic speed at 20 °C here in absence of the
	 * temperature
	 *
	 * therefore:
	 *             time     343
	 * distance = ------ * -----
	 *             10^6       2
	 *   with time in ns
	 *   and distance in mm (one way)
	 *
	 * because we limit to 3 meters the multiplication with 343 just
	 * fits into 32 bit
	 */
	distance_mm = time_ns * 343 / 2000000;

	return distance_mm;
}

static int srf04_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *channel, int *val,
			    int *val2, long info)
{
	struct srf04_data *data = iio_priv(indio_dev);
	int ret;

	if (channel->type != IIO_DISTANCE)
		return -EINVAL;

	switch (info) {
	case IIO_CHAN_INFO_RAW:
		ret = srf04_read(data);
		if (ret < 0)
			return ret;
		*val = ret;
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		/*
		 * theoretical maximum resolution is 3 mm
		 * 1 LSB is 1 mm
		 */
		*val = 0;
		*val2 = 1000;
		return IIO_VAL_INT_PLUS_MICRO;
	default:
		return -EINVAL;
	}
}

static const struct iio_info srf04_iio_info = {
	.read_raw		= srf04_read_raw,
};

static const struct iio_chan_spec srf04_chan_spec[] = {
	{
		.type = IIO_DISTANCE,
		.info_mask_separate =
				BIT(IIO_CHAN_INFO_RAW) |
				BIT(IIO_CHAN_INFO_SCALE),
	},
};

static const struct of_device_id of_srf04_match[] = {
	{ .compatible = "devantech,srf04", .data = &srf04_cfg},
	{ .compatible = "maxbotix,mb1000", .data = &mb_lv_cfg},
	{ .compatible = "maxbotix,mb1010", .data = &mb_lv_cfg},
	{ .compatible = "maxbotix,mb1020", .data = &mb_lv_cfg},
	{ .compatible = "maxbotix,mb1030", .data = &mb_lv_cfg},
	{ .compatible = "maxbotix,mb1040", .data = &mb_lv_cfg},
	{},
};

MODULE_DEVICE_TABLE(of, of_srf04_match);

static int srf04_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct srf04_data *data;
	struct iio_dev *indio_dev;
	int ret;

	indio_dev = devm_iio_device_alloc(dev, sizeof(struct srf04_data));
	if (!indio_dev) {
		dev_err(dev, "failed to allocate IIO device\n");
		return -ENOMEM;
	}

	data = iio_priv(indio_dev);
	data->dev = dev;
	data->cfg = of_match_device(of_srf04_match, dev)->data;

	mutex_init(&data->lock);
	init_completion(&data->rising);
	init_completion(&data->falling);

	data->gpiod_trig = devm_gpiod_get(dev, "trig", GPIOD_OUT_LOW);
	if (IS_ERR(data->gpiod_trig)) {
		dev_err(dev, "failed to get trig-gpios: err=%ld\n",
					PTR_ERR(data->gpiod_trig));
		return PTR_ERR(data->gpiod_trig);
	}

	data->gpiod_echo = devm_gpiod_get(dev, "echo", GPIOD_IN);
	if (IS_ERR(data->gpiod_echo)) {
		dev_err(dev, "failed to get echo-gpios: err=%ld\n",
					PTR_ERR(data->gpiod_echo));
		return PTR_ERR(data->gpiod_echo);
	}

	if (gpiod_cansleep(data->gpiod_echo)) {
		dev_err(data->dev, "cansleep-GPIOs not supported\n");
		return -ENODEV;
	}

	data->irqnr = gpiod_to_irq(data->gpiod_echo);
	if (data->irqnr < 0) {
		dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr);
		return data->irqnr;
	}

	ret = devm_request_irq(dev, data->irqnr, srf04_handle_irq,
			IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
			pdev->name, indio_dev);
	if (ret < 0) {
		dev_err(data->dev, "request_irq: %d\n", ret);
		return ret;
	}

	platform_set_drvdata(pdev, indio_dev);

	indio_dev->name = "srf04";
	indio_dev->dev.parent = &pdev->dev;
	indio_dev->info = &srf04_iio_info;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = srf04_chan_spec;
	indio_dev->num_channels = ARRAY_SIZE(srf04_chan_spec);

	return devm_iio_device_register(dev, indio_dev);
}

static struct platform_driver srf04_driver = {
	.probe		= srf04_probe,
	.driver		= {
		.name		= "srf04-gpio",
		.of_match_table	= of_srf04_match,
	},
};

module_platform_driver(srf04_driver);

MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
MODULE_DESCRIPTION("SRF04 ultrasonic sensor for distance measuring using GPIOs");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:srf04");
Commit	Line	Data
c942fddf	1	// SPDX-License-Identifier: GPL-2.0-or-later
feda2840 AK	2	/*
	3	* SRF04: ultrasonic sensor for distance measuring by using GPIOs
	4	*
	5	* Copyright (c) 2017 Andreas Klinger <ak@it-klinger.de>
	6	*
feda2840 AK	7	* For details about the device see:
	8	* http://www.robot-electronics.co.uk/htm/srf04tech.htm
	9	*
	10	* the measurement cycle as timing diagram looks like:
	11	*
	12	* +---+
	13	* GPIO \| \|
	14	* trig: --+ +------------------------------------------------------
	15	* ^ ^
	16	* \|<->\|
bb208037	17	* udelay(trigger_pulse_us)
feda2840 AK	18	*
	19	* ultra +-+ +-+ +-+
	20	* sonic \| \| \| \| \| \|
	21	* burst: ---------+ +-+ +-+ +-----------------------------------------
	22	* .
	23	* ultra . +-+ +-+ +-+
	24	* sonic . \| \| \| \| \| \|
	25	* echo: ----------------------------------+ +-+ +-+ +----------------
	26	* . .
	27	* +------------------------+
	28	* GPIO \| \|
	29	* echo: -------------------+ +---------------
	30	* ^ ^
	31	* interrupt interrupt
	32	* (ts_rising) (ts_falling)
	33	* \|<---------------------->\|
	34	* pulse time measured
	35	* --> one round trip of ultra sonic waves
	36	*/
	37	#include <linux/err.h>
	38	#include <linux/gpio/consumer.h>
	39	#include <linux/kernel.h>
	40	#include <linux/module.h>
	41	#include <linux/of.h>
bb208037	42	#include <linux/of_device.h>
feda2840 AK	43	#include <linux/platform_device.h>
	44	#include <linux/property.h>
	45	#include <linux/sched.h>
	46	#include <linux/interrupt.h>
	47	#include <linux/delay.h>
	48	#include <linux/iio/iio.h>
	49	#include <linux/iio/sysfs.h>
	50
bb208037 AK	51	struct srf04_cfg {
	52	unsigned long trigger_pulse_us;
	53	};
	54
feda2840 AK	55	struct srf04_data {
	56	struct device *dev;
	57	struct gpio_desc *gpiod_trig;
	58	struct gpio_desc *gpiod_echo;
	59	struct mutex lock;
	60	int irqnr;
	61	ktime_t ts_rising;
	62	ktime_t ts_falling;
	63	struct completion rising;
	64	struct completion falling;
bb208037 AK	65	const struct srf04_cfg *cfg;
	66	};
	67
	68	static const struct srf04_cfg srf04_cfg = {
	69	.trigger_pulse_us = 10,
	70	};
	71
	72	static const struct srf04_cfg mb_lv_cfg = {
	73	.trigger_pulse_us = 20,
feda2840 AK	74	};
	75
	76	static irqreturn_t srf04_handle_irq(int irq, void *dev_id)
	77	{
	78	struct iio_dev *indio_dev = dev_id;
	79	struct srf04_data *data = iio_priv(indio_dev);
	80	ktime_t now = ktime_get();
	81
	82	if (gpiod_get_value(data->gpiod_echo)) {
	83	data->ts_rising = now;
	84	complete(&data->rising);
	85	} else {
	86	data->ts_falling = now;
	87	complete(&data->falling);
	88	}
	89
	90	return IRQ_HANDLED;
	91	}
	92
	93	static int srf04_read(struct srf04_data *data)
	94	{
	95	int ret;
	96	ktime_t ktime_dt;
	97	u64 dt_ns;
	98	u32 time_ns, distance_mm;
	99
	100	/*
	101	* just one read-echo-cycle can take place at a time
	102	* ==> lock against concurrent reading calls
	103	*/
	104	mutex_lock(&data->lock);
	105
	106	reinit_completion(&data->rising);
	107	reinit_completion(&data->falling);
	108
	109	gpiod_set_value(data->gpiod_trig, 1);
bb208037	110	udelay(data->cfg->trigger_pulse_us);
feda2840 AK	111	gpiod_set_value(data->gpiod_trig, 0);
	112
	113	/* it cannot take more than 20 ms */
	114	ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);
	115	if (ret < 0) {
	116	mutex_unlock(&data->lock);
	117	return ret;
	118	} else if (ret == 0) {
	119	mutex_unlock(&data->lock);
	120	return -ETIMEDOUT;
	121	}
	122
	123	ret = wait_for_completion_killable_timeout(&data->falling, HZ/50);
	124	if (ret < 0) {
	125	mutex_unlock(&data->lock);
	126	return ret;
	127	} else if (ret == 0) {
	128	mutex_unlock(&data->lock);
	129	return -ETIMEDOUT;
	130	}
	131
	132	ktime_dt = ktime_sub(data->ts_falling, data->ts_rising);
	133
	134	mutex_unlock(&data->lock);
	135
	136	dt_ns = ktime_to_ns(ktime_dt);
	137	/*
	138	* measuring more than 3 meters is beyond the capabilities of
	139	* the sensor
	140	* ==> filter out invalid results for not measuring echos of
	141	* another us sensor
	142	*
	143	* formula:
	144	* distance 3 m
	145	* time = ---------- = --------- = 9404389 ns
	146	* speed 319 m/s
	147	*
	148	* using a minimum speed at -20 °C of 319 m/s
	149	*/
	150	if (dt_ns > 9404389)
	151	return -EIO;
	152
	153	time_ns = dt_ns;
	154
	155	/*
	156	* the speed as function of the temperature is approximately:
	157	*
	158	* speed = 331,5 + 0,6 * Temp
	159	* with Temp in °C
	160	* and speed in m/s
	161	*
	162	* use 343 m/s as ultrasonic speed at 20 °C here in absence of the
	163	* temperature
	164	*
	165	* therefore:
	166	* time 343
	167	* distance = ------ * -----
	168	* 10^6 2
	169	* with time in ns
	170	* and distance in mm (one way)
	171	*
	172	* because we limit to 3 meters the multiplication with 343 just
	173	* fits into 32 bit
	174	*/
175	distance_mm = time_ns * 343 / 2000000;
176
177	return distance_mm;
178	}
179
180	static int srf04_read_raw(struct iio_dev *indio_dev,
181	struct iio_chan_spec const channel, int val,
182	int *val2, long info)
183	{
184	struct srf04_data *data = iio_priv(indio_dev);
185	int ret;
186
187	if (channel->type != IIO_DISTANCE)
188	return -EINVAL;
189
190	switch (info) {
191	case IIO_CHAN_INFO_RAW:
192	ret = srf04_read(data);
193	if (ret < 0)
194	return ret;
195	*val = ret;
196	return IIO_VAL_INT;
197	case IIO_CHAN_INFO_SCALE:
198	/*
199	* theoretical maximum resolution is 3 mm
200	* 1 LSB is 1 mm
201	*/
202	*val = 0;
203	*val2 = 1000;
204	return IIO_VAL_INT_PLUS_MICRO;
205	default:
206	return -EINVAL;
207	}
208	}
209
210	static const struct iio_info srf04_iio_info = {
feda2840 AK	211	.read_raw = srf04_read_raw,
	212	};
	213
	214	static const struct iio_chan_spec srf04_chan_spec[] = {
	215	{
	216	.type = IIO_DISTANCE,
	217	.info_mask_separate =
	218	BIT(IIO_CHAN_INFO_RAW) \|
	219	BIT(IIO_CHAN_INFO_SCALE),
	220	},
	221	};
	222
bb208037 AK	223	static const struct of_device_id of_srf04_match[] = {
	224	{ .compatible = "devantech,srf04", .data = &srf04_cfg},
	225	{ .compatible = "maxbotix,mb1000", .data = &mb_lv_cfg},
	226	{ .compatible = "maxbotix,mb1010", .data = &mb_lv_cfg},
	227	{ .compatible = "maxbotix,mb1020", .data = &mb_lv_cfg},
	228	{ .compatible = "maxbotix,mb1030", .data = &mb_lv_cfg},
	229	{ .compatible = "maxbotix,mb1040", .data = &mb_lv_cfg},
	230	{},
	231	};
	232
	233	MODULE_DEVICE_TABLE(of, of_srf04_match);
	234
feda2840 AK	235	static int srf04_probe(struct platform_device *pdev)
	236	{
	237	struct device *dev = &pdev->dev;
	238	struct srf04_data *data;
	239	struct iio_dev *indio_dev;
	240	int ret;
	241
	242	indio_dev = devm_iio_device_alloc(dev, sizeof(struct srf04_data));
	243	if (!indio_dev) {
	244	dev_err(dev, "failed to allocate IIO device\n");
	245	return -ENOMEM;
	246	}
	247
	248	data = iio_priv(indio_dev);
	249	data->dev = dev;
bb208037	250	data->cfg = of_match_device(of_srf04_match, dev)->data;
feda2840 AK	251
	252	mutex_init(&data->lock);
	253	init_completion(&data->rising);
	254	init_completion(&data->falling);
	255
	256	data->gpiod_trig = devm_gpiod_get(dev, "trig", GPIOD_OUT_LOW);
	257	if (IS_ERR(data->gpiod_trig)) {
	258	dev_err(dev, "failed to get trig-gpios: err=%ld\n",
	259	PTR_ERR(data->gpiod_trig));
	260	return PTR_ERR(data->gpiod_trig);
	261	}
	262
	263	data->gpiod_echo = devm_gpiod_get(dev, "echo", GPIOD_IN);
	264	if (IS_ERR(data->gpiod_echo)) {
	265	dev_err(dev, "failed to get echo-gpios: err=%ld\n",
	266	PTR_ERR(data->gpiod_echo));
	267	return PTR_ERR(data->gpiod_echo);
	268	}
	269
	270	if (gpiod_cansleep(data->gpiod_echo)) {
	271	dev_err(data->dev, "cansleep-GPIOs not supported\n");
	272	return -ENODEV;
	273	}
	274
	275	data->irqnr = gpiod_to_irq(data->gpiod_echo);
	276	if (data->irqnr < 0) {
	277	dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr);
	278	return data->irqnr;
	279	}
	280
	281	ret = devm_request_irq(dev, data->irqnr, srf04_handle_irq,
	282	IRQF_TRIGGER_RISING \| IRQF_TRIGGER_FALLING,
	283	pdev->name, indio_dev);
	284	if (ret < 0) {
	285	dev_err(data->dev, "request_irq: %d\n", ret);
	286	return ret;
	287	}
	288
	289	platform_set_drvdata(pdev, indio_dev);
	290
	291	indio_dev->name = "srf04";
	292	indio_dev->dev.parent = &pdev->dev;
	293	indio_dev->info = &srf04_iio_info;
	294	indio_dev->modes = INDIO_DIRECT_MODE;
	295	indio_dev->channels = srf04_chan_spec;
	296	indio_dev->num_channels = ARRAY_SIZE(srf04_chan_spec);
	297
	298	return devm_iio_device_register(dev, indio_dev);
	299	}
	300
feda2840 AK	301	static struct platform_driver srf04_driver = {
	302	.probe = srf04_probe,
	303	.driver = {
	304	.name = "srf04-gpio",
	305	.of_match_table = of_srf04_match,
	306	},
	307	};
	308
	309	module_platform_driver(srf04_driver);
	310
	311	MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
	312	MODULE_DESCRIPTION("SRF04 ultrasonic sensor for distance measuring using GPIOs");
	313	MODULE_LICENSE("GPL");
	314	MODULE_ALIAS("platform:srf04");