summaryrefslogtreecommitdiffstats
path: root/drivers/iio/proximity/srf04.c
blob: 568b76e063859a9f892a3b5754f3c419bcc048b7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
// 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/pm_runtime.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 gpio_desc	*gpiod_power;
	struct mutex		lock;
	int			irqnr;
	ktime_t			ts_rising;
	ktime_t			ts_falling;
	struct completion	rising;
	struct completion	falling;
	const struct srf04_cfg	*cfg;
	int			startup_time_ms;
};

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;

	if (data->gpiod_power)
		pm_runtime_get_sync(data->dev);

	/*
	 * 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);

	if (data->gpiod_power) {
		pm_runtime_mark_last_busy(data->dev);
		pm_runtime_put_autosuspend(data->dev);
	}

	/* it should not take more than 20 ms until echo is rising */
	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;
	}

	/* it cannot take more than 50 ms until echo is falling */
	ret = wait_for_completion_killable_timeout(&data->falling, HZ/20);
	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 6,45 meters is beyond the capabilities of
	 * the supported sensors
	 * ==> filter out invalid results for not measuring echos of
	 *     another us sensor
	 *
	 * formula:
	 *         distance     6,45 * 2 m
	 * time = ---------- = ------------ = 40438871 ns
	 *          speed         319 m/s
	 *
	 * using a minimum speed at -20 °C of 319 m/s
	 */
	if (dt_ns > 40438871)
		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 343,5 m/s as ultrasonic speed at 20 °C here in absence of the
	 * temperature
	 *
	 * therefore:
	 *             time     343,5     time * 106
	 * distance = ------ * ------- = ------------
	 *             10^6         2         617176
	 *   with time in ns
	 *   and distance in mm (one way)
	 *
	 * because we limit to 6,45 meters the multiplication with 106 just
	 * fits into 32 bit
	 */
	distance_mm = time_ns * 106 / 617176;

	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);
	}

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

		if (of_property_read_u32(dev->of_node, "startup-time-ms",
						&data->startup_time_ms))
			data->startup_time_ms = 100;
		dev_dbg(dev, "using power gpio: startup-time-ms=%d\n",
							data->startup_time_ms);
	}

	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);

	ret = iio_device_register(indio_dev);
	if (ret < 0) {
		dev_err(data->dev, "iio_device_register: %d\n", ret);
		return ret;
	}

	if (data->gpiod_power) {
		pm_runtime_set_autosuspend_delay(data->dev, 1000);
		pm_runtime_use_autosuspend(data->dev);

		ret = pm_runtime_set_active(data->dev);
		if (ret) {
			dev_err(data->dev, "pm_runtime_set_active: %d\n", ret);
			iio_device_unregister(indio_dev);
		}

		pm_runtime_enable(data->dev);
		pm_runtime_idle(data->dev);
	}

	return ret;
}

static int srf04_remove(struct platform_device *pdev)
{
	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
	struct srf04_data *data = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);

	if (data->gpiod_power) {
		pm_runtime_disable(data->dev);
		pm_runtime_set_suspended(data->dev);
	}

	return 0;
}

static int __maybe_unused srf04_pm_runtime_suspend(struct device *dev)
{
	struct platform_device *pdev = container_of(dev,
						struct platform_device, dev);
	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
	struct srf04_data *data = iio_priv(indio_dev);

	gpiod_set_value(data->gpiod_power, 0);

	return 0;
}

static int __maybe_unused srf04_pm_runtime_resume(struct device *dev)
{
	struct platform_device *pdev = container_of(dev,
						struct platform_device, dev);
	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
	struct srf04_data *data = iio_priv(indio_dev);

	gpiod_set_value(data->gpiod_power, 1);
	msleep(data->startup_time_ms);

	return 0;
}

static const struct dev_pm_ops srf04_pm_ops = {
	SET_RUNTIME_PM_OPS(srf04_pm_runtime_suspend,
				srf04_pm_runtime_resume, NULL)
};

static struct platform_driver srf04_driver = {
	.probe		= srf04_probe,
	.remove		= srf04_remove,
	.driver		= {
		.name		= "srf04-gpio",
		.of_match_table	= of_srf04_match,
		.pm		= &srf04_pm_ops,
	},
};

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");