srf04.c (664b0bae0b87f69bc9deb098f5e0158b9cf18e04) srf04.c (bb208037ae45eb891765f0cff4198e9f58da7bd8)
1/*
2 * SRF04: ultrasonic sensor for distance measuring by using GPIOs
3 *
4 * Copyright (c) 2017 Andreas Klinger <ak@it-klinger.de>
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

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18 *
19 * the measurement cycle as timing diagram looks like:
20 *
21 * +---+
22 * GPIO | |
23 * trig: --+ +------------------------------------------------------
24 * ^ ^
25 * |<->|
1/*
2 * SRF04: ultrasonic sensor for distance measuring by using GPIOs
3 *
4 * Copyright (c) 2017 Andreas Klinger <ak@it-klinger.de>
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

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18 *
19 * the measurement cycle as timing diagram looks like:
20 *
21 * +---+
22 * GPIO | |
23 * trig: --+ +------------------------------------------------------
24 * ^ ^
25 * |<->|
26 * udelay(10)
26 * udelay(trigger_pulse_us)
27 *
28 * ultra +-+ +-+ +-+
29 * sonic | | | | | |
30 * burst: ---------+ +-+ +-+ +-----------------------------------------
31 * .
32 * ultra . +-+ +-+ +-+
33 * sonic . | | | | | |
34 * echo: ----------------------------------+ +-+ +-+ +----------------

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43 * pulse time measured
44 * --> one round trip of ultra sonic waves
45 */
46#include <linux/err.h>
47#include <linux/gpio/consumer.h>
48#include <linux/kernel.h>
49#include <linux/module.h>
50#include <linux/of.h>
27 *
28 * ultra +-+ +-+ +-+
29 * sonic | | | | | |
30 * burst: ---------+ +-+ +-+ +-----------------------------------------
31 * .
32 * ultra . +-+ +-+ +-+
33 * sonic . | | | | | |
34 * echo: ----------------------------------+ +-+ +-+ +----------------

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43 * pulse time measured
44 * --> one round trip of ultra sonic waves
45 */
46#include <linux/err.h>
47#include <linux/gpio/consumer.h>
48#include <linux/kernel.h>
49#include <linux/module.h>
50#include <linux/of.h>
51#include <linux/of_device.h>
51#include <linux/platform_device.h>
52#include <linux/property.h>
53#include <linux/sched.h>
54#include <linux/interrupt.h>
55#include <linux/delay.h>
56#include <linux/iio/iio.h>
57#include <linux/iio/sysfs.h>
58
52#include <linux/platform_device.h>
53#include <linux/property.h>
54#include <linux/sched.h>
55#include <linux/interrupt.h>
56#include <linux/delay.h>
57#include <linux/iio/iio.h>
58#include <linux/iio/sysfs.h>
59
60struct srf04_cfg {
61 unsigned long trigger_pulse_us;
62};
63
59struct srf04_data {
60 struct device *dev;
61 struct gpio_desc *gpiod_trig;
62 struct gpio_desc *gpiod_echo;
63 struct mutex lock;
64 int irqnr;
65 ktime_t ts_rising;
66 ktime_t ts_falling;
67 struct completion rising;
68 struct completion falling;
64struct srf04_data {
65 struct device *dev;
66 struct gpio_desc *gpiod_trig;
67 struct gpio_desc *gpiod_echo;
68 struct mutex lock;
69 int irqnr;
70 ktime_t ts_rising;
71 ktime_t ts_falling;
72 struct completion rising;
73 struct completion falling;
74 const struct srf04_cfg *cfg;
69};
70
75};
76
77static const struct srf04_cfg srf04_cfg = {
78 .trigger_pulse_us = 10,
79};
80
81static const struct srf04_cfg mb_lv_cfg = {
82 .trigger_pulse_us = 20,
83};
84
71static irqreturn_t srf04_handle_irq(int irq, void *dev_id)
72{
73 struct iio_dev *indio_dev = dev_id;
74 struct srf04_data *data = iio_priv(indio_dev);
75 ktime_t now = ktime_get();
76
77 if (gpiod_get_value(data->gpiod_echo)) {
78 data->ts_rising = now;

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97 * ==> lock against concurrent reading calls
98 */
99 mutex_lock(&data->lock);
100
101 reinit_completion(&data->rising);
102 reinit_completion(&data->falling);
103
104 gpiod_set_value(data->gpiod_trig, 1);
85static irqreturn_t srf04_handle_irq(int irq, void *dev_id)
86{
87 struct iio_dev *indio_dev = dev_id;
88 struct srf04_data *data = iio_priv(indio_dev);
89 ktime_t now = ktime_get();
90
91 if (gpiod_get_value(data->gpiod_echo)) {
92 data->ts_rising = now;

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111 * ==> lock against concurrent reading calls
112 */
113 mutex_lock(&data->lock);
114
115 reinit_completion(&data->rising);
116 reinit_completion(&data->falling);
117
118 gpiod_set_value(data->gpiod_trig, 1);
105 udelay(10);
119 udelay(data->cfg->trigger_pulse_us);
106 gpiod_set_value(data->gpiod_trig, 0);
107
108 /* it cannot take more than 20 ms */
109 ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);
110 if (ret < 0) {
111 mutex_unlock(&data->lock);
112 return ret;
113 } else if (ret == 0) {

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210 {
211 .type = IIO_DISTANCE,
212 .info_mask_separate =
213 BIT(IIO_CHAN_INFO_RAW) |
214 BIT(IIO_CHAN_INFO_SCALE),
215 },
216};
217
120 gpiod_set_value(data->gpiod_trig, 0);
121
122 /* it cannot take more than 20 ms */
123 ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);
124 if (ret < 0) {
125 mutex_unlock(&data->lock);
126 return ret;
127 } else if (ret == 0) {

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224 {
225 .type = IIO_DISTANCE,
226 .info_mask_separate =
227 BIT(IIO_CHAN_INFO_RAW) |
228 BIT(IIO_CHAN_INFO_SCALE),
229 },
230};
231
232static const struct of_device_id of_srf04_match[] = {
233 { .compatible = "devantech,srf04", .data = &srf04_cfg},
234 { .compatible = "maxbotix,mb1000", .data = &mb_lv_cfg},
235 { .compatible = "maxbotix,mb1010", .data = &mb_lv_cfg},
236 { .compatible = "maxbotix,mb1020", .data = &mb_lv_cfg},
237 { .compatible = "maxbotix,mb1030", .data = &mb_lv_cfg},
238 { .compatible = "maxbotix,mb1040", .data = &mb_lv_cfg},
239 {},
240};
241
242MODULE_DEVICE_TABLE(of, of_srf04_match);
243
218static int srf04_probe(struct platform_device *pdev)
219{
220 struct device *dev = &pdev->dev;
221 struct srf04_data *data;
222 struct iio_dev *indio_dev;
223 int ret;
224
225 indio_dev = devm_iio_device_alloc(dev, sizeof(struct srf04_data));
226 if (!indio_dev) {
227 dev_err(dev, "failed to allocate IIO device\n");
228 return -ENOMEM;
229 }
230
231 data = iio_priv(indio_dev);
232 data->dev = dev;
244static int srf04_probe(struct platform_device *pdev)
245{
246 struct device *dev = &pdev->dev;
247 struct srf04_data *data;
248 struct iio_dev *indio_dev;
249 int ret;
250
251 indio_dev = devm_iio_device_alloc(dev, sizeof(struct srf04_data));
252 if (!indio_dev) {
253 dev_err(dev, "failed to allocate IIO device\n");
254 return -ENOMEM;
255 }
256
257 data = iio_priv(indio_dev);
258 data->dev = dev;
259 data->cfg = of_match_device(of_srf04_match, dev)->data;
233
234 mutex_init(&data->lock);
235 init_completion(&data->rising);
236 init_completion(&data->falling);
237
238 data->gpiod_trig = devm_gpiod_get(dev, "trig", GPIOD_OUT_LOW);
239 if (IS_ERR(data->gpiod_trig)) {
240 dev_err(dev, "failed to get trig-gpios: err=%ld\n",

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275 indio_dev->info = &srf04_iio_info;
276 indio_dev->modes = INDIO_DIRECT_MODE;
277 indio_dev->channels = srf04_chan_spec;
278 indio_dev->num_channels = ARRAY_SIZE(srf04_chan_spec);
279
280 return devm_iio_device_register(dev, indio_dev);
281}
282
260
261 mutex_init(&data->lock);
262 init_completion(&data->rising);
263 init_completion(&data->falling);
264
265 data->gpiod_trig = devm_gpiod_get(dev, "trig", GPIOD_OUT_LOW);
266 if (IS_ERR(data->gpiod_trig)) {
267 dev_err(dev, "failed to get trig-gpios: err=%ld\n",

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302 indio_dev->info = &srf04_iio_info;
303 indio_dev->modes = INDIO_DIRECT_MODE;
304 indio_dev->channels = srf04_chan_spec;
305 indio_dev->num_channels = ARRAY_SIZE(srf04_chan_spec);
306
307 return devm_iio_device_register(dev, indio_dev);
308}
309
283static const struct of_device_id of_srf04_match[] = {
284 { .compatible = "devantech,srf04", },
285 {},
286};
287
288MODULE_DEVICE_TABLE(of, of_srf04_match);
289
290static struct platform_driver srf04_driver = {
291 .probe = srf04_probe,
292 .driver = {
293 .name = "srf04-gpio",
294 .of_match_table = of_srf04_match,
295 },
296};
297
298module_platform_driver(srf04_driver);
299
300MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
301MODULE_DESCRIPTION("SRF04 ultrasonic sensor for distance measuring using GPIOs");
302MODULE_LICENSE("GPL");
303MODULE_ALIAS("platform:srf04");
310static struct platform_driver srf04_driver = {
311 .probe = srf04_probe,
312 .driver = {
313 .name = "srf04-gpio",
314 .of_match_table = of_srf04_match,
315 },
316};
317
318module_platform_driver(srf04_driver);
319
320MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
321MODULE_DESCRIPTION("SRF04 ultrasonic sensor for distance measuring using GPIOs");
322MODULE_LICENSE("GPL");
323MODULE_ALIAS("platform:srf04");