1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * SRF04: ultrasonic sensor for distance measuring by using GPIOs
5  * Copyright (c) 2017 Andreas Klinger <ak@it-klinger.de>
8  * https://www.robot-electronics.co.uk/htm/srf04tech.htm
12  *          +---+
14  * trig:  --+   +------------------------------------------------------
16  *          |<->|
19  * ultra           +-+ +-+ +-+
21  * burst: ---------+ +-+ +-+ +-----------------------------------------
23  * ultra                     .              +-+ +-+ +-+
25  * echo:  ----------------------------------+ +-+ +-+ +----------------
27  *                           +------------------------+
29  * echo:  -------------------+                        +---------------
33  *                           |<---------------------->|
35  *                              --> one round trip of ultra sonic waves
84 	if (gpiod_get_value(data->gpiod_echo)) {  in srf04_handle_irq()
85 		data->ts_rising = now;  in srf04_handle_irq()
86 		complete(&data->rising);  in srf04_handle_irq()
88 		data->ts_falling = now;  in srf04_handle_irq()
89 		complete(&data->falling);  in srf04_handle_irq()
102 	if (data->gpiod_power) {  in srf04_read()
103 		ret = pm_runtime_resume_and_get(data->dev);  in srf04_read()
108 	 * just one read-echo-cycle can take place at a time  in srf04_read()
111 	mutex_lock(&data->lock);  in srf04_read()
113 	reinit_completion(&data->rising);  in srf04_read()
114 	reinit_completion(&data->falling);  in srf04_read()
116 	gpiod_set_value(data->gpiod_trig, 1);  in srf04_read()
117 	udelay(data->cfg->trigger_pulse_us);  in srf04_read()
118 	gpiod_set_value(data->gpiod_trig, 0);  in srf04_read()
120 	if (data->gpiod_power) {  in srf04_read()
121 		pm_runtime_mark_last_busy(data->dev);  in srf04_read()
122 		pm_runtime_put_autosuspend(data->dev);  in srf04_read()
125 	/* it should not take more than 20 ms until echo is rising */  in srf04_read()
126 	ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);  in srf04_read()
128 		mutex_unlock(&data->lock);  in srf04_read()
131 		mutex_unlock(&data->lock);  in srf04_read()
132 		return -ETIMEDOUT;  in srf04_read()
135 	/* it cannot take more than 50 ms until echo is falling */  in srf04_read()
136 	ret = wait_for_completion_killable_timeout(&data->falling, HZ/20);  in srf04_read()
138 		mutex_unlock(&data->lock);  in srf04_read()
141 		mutex_unlock(&data->lock);  in srf04_read()
142 		return -ETIMEDOUT;  in srf04_read()
145 	ktime_dt = ktime_sub(data->ts_falling, data->ts_rising);  in srf04_read()
147 	mutex_unlock(&data->lock);  in srf04_read()
158 	 * time = ---------- = ------------ = 40438871 ns  in srf04_read()
161 	 * using a minimum speed at -20 °C of 319 m/s  in srf04_read()
164 		return -EIO;  in srf04_read()
180 	 * distance = ------ * ------- = ------------  in srf04_read()
200 	if (channel->type != IIO_DISTANCE)  in srf04_read_raw()
201 		return -EINVAL;  in srf04_read_raw()
219 		return -EINVAL;  in srf04_read_raw()
250 	struct device *dev = &pdev->dev;  in srf04_probe()
258 		return -ENOMEM;  in srf04_probe()
262 	data->dev = dev;  in srf04_probe()
263 	data->cfg = device_get_match_data(dev);  in srf04_probe()
265 	mutex_init(&data->lock);  in srf04_probe()
266 	init_completion(&data->rising);  in srf04_probe()
267 	init_completion(&data->falling);  in srf04_probe()
269 	data->gpiod_trig = devm_gpiod_get(dev, "trig", GPIOD_OUT_LOW);  in srf04_probe()
270 	if (IS_ERR(data->gpiod_trig)) {  in srf04_probe()
271 		dev_err(dev, "failed to get trig-gpios: err=%ld\n",  in srf04_probe()
272 					PTR_ERR(data->gpiod_trig));  in srf04_probe()
273 		return PTR_ERR(data->gpiod_trig);  in srf04_probe()
276 	data->gpiod_echo = devm_gpiod_get(dev, "echo", GPIOD_IN);  in srf04_probe()
277 	if (IS_ERR(data->gpiod_echo)) {  in srf04_probe()
278 		dev_err(dev, "failed to get echo-gpios: err=%ld\n",  in srf04_probe()
279 					PTR_ERR(data->gpiod_echo));  in srf04_probe()
280 		return PTR_ERR(data->gpiod_echo);  in srf04_probe()
283 	data->gpiod_power = devm_gpiod_get_optional(dev, "power",  in srf04_probe()
285 	if (IS_ERR(data->gpiod_power)) {  in srf04_probe()
286 		dev_err(dev, "failed to get power-gpios: err=%ld\n",  in srf04_probe()
287 						PTR_ERR(data->gpiod_power));  in srf04_probe()
288 		return PTR_ERR(data->gpiod_power);  in srf04_probe()
290 	if (data->gpiod_power) {  in srf04_probe()
291 		data->startup_time_ms = 100;  in srf04_probe()
292 		device_property_read_u32(dev, "startup-time-ms", &data->startup_time_ms);  in srf04_probe()
293 		dev_dbg(dev, "using power gpio: startup-time-ms=%d\n",  in srf04_probe()
294 							data->startup_time_ms);  in srf04_probe()
297 	if (gpiod_cansleep(data->gpiod_echo)) {  in srf04_probe()
298 		dev_err(data->dev, "cansleep-GPIOs not supported\n");  in srf04_probe()
299 		return -ENODEV;  in srf04_probe()
302 	data->irqnr = gpiod_to_irq(data->gpiod_echo);  in srf04_probe()
303 	if (data->irqnr < 0) {  in srf04_probe()
304 		dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr);  in srf04_probe()
305 		return data->irqnr;  in srf04_probe()
308 	ret = devm_request_irq(dev, data->irqnr, srf04_handle_irq,  in srf04_probe()
310 			pdev->name, indio_dev);  in srf04_probe()
312 		dev_err(data->dev, "request_irq: %d\n", ret);  in srf04_probe()
318 	indio_dev->name = "srf04";  in srf04_probe()
319 	indio_dev->info = &srf04_iio_info;  in srf04_probe()
320 	indio_dev->modes = INDIO_DIRECT_MODE;  in srf04_probe()
321 	indio_dev->channels = srf04_chan_spec;  in srf04_probe()
322 	indio_dev->num_channels = ARRAY_SIZE(srf04_chan_spec);  in srf04_probe()
326 		dev_err(data->dev, "iio_device_register: %d\n", ret);  in srf04_probe()
330 	if (data->gpiod_power) {  in srf04_probe()
331 		pm_runtime_set_autosuspend_delay(data->dev, 1000);  in srf04_probe()
332 		pm_runtime_use_autosuspend(data->dev);  in srf04_probe()
334 		ret = pm_runtime_set_active(data->dev);  in srf04_probe()
336 			dev_err(data->dev, "pm_runtime_set_active: %d\n", ret);  in srf04_probe()
340 		pm_runtime_enable(data->dev);  in srf04_probe()
341 		pm_runtime_idle(data->dev);  in srf04_probe()
354 	if (data->gpiod_power) {  in srf04_remove()
355 		pm_runtime_disable(data->dev);  in srf04_remove()
356 		pm_runtime_set_suspended(data->dev);  in srf04_remove()
367 	gpiod_set_value(data->gpiod_power, 0);  in srf04_pm_runtime_suspend()
379 	gpiod_set_value(data->gpiod_power, 1);  in srf04_pm_runtime_resume()
380 	msleep(data->startup_time_ms);  in srf04_pm_runtime_resume()
394 		.name		= "srf04-gpio",
402 MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
403 MODULE_DESCRIPTION("SRF04 ultrasonic sensor for distance measuring using GPIOs");