17bb501f4SAndreas Klinger // SPDX-License-Identifier: GPL-2.0-or-later
27bb501f4SAndreas Klinger /*
37bb501f4SAndreas Klinger * PING: ultrasonic sensor for distance measuring by using only one GPIOs
47bb501f4SAndreas Klinger *
57bb501f4SAndreas Klinger * Copyright (c) 2019 Andreas Klinger <ak@it-klinger.de>
67bb501f4SAndreas Klinger *
77bb501f4SAndreas Klinger * For details about the devices see:
87bb501f4SAndreas Klinger * http://parallax.com/sites/default/files/downloads/28041-LaserPING-2m-Rangefinder-Guide.pdf
97bb501f4SAndreas Klinger * http://parallax.com/sites/default/files/downloads/28015-PING-Documentation-v1.6.pdf
107bb501f4SAndreas Klinger *
117bb501f4SAndreas Klinger * the measurement cycle as timing diagram looks like:
127bb501f4SAndreas Klinger *
137bb501f4SAndreas Klinger * GPIO ___ ________________________
147bb501f4SAndreas Klinger * ping: __/ \____________/ \________________
157bb501f4SAndreas Klinger * ^ ^ ^ ^
167bb501f4SAndreas Klinger * |<->| interrupt interrupt
177bb501f4SAndreas Klinger * udelay(5) (ts_rising) (ts_falling)
187bb501f4SAndreas Klinger * |<---------------------->|
197bb501f4SAndreas Klinger * . pulse time measured .
207bb501f4SAndreas Klinger * . --> one round trip of ultra sonic waves
217bb501f4SAndreas Klinger * ultra . .
227bb501f4SAndreas Klinger * sonic _ _ _. .
237bb501f4SAndreas Klinger * burst: _________/ \_/ \_/ \_________________________________________
247bb501f4SAndreas Klinger * .
257bb501f4SAndreas Klinger * ultra .
267bb501f4SAndreas Klinger * sonic _ _ _.
277bb501f4SAndreas Klinger * echo: __________________________________/ \_/ \_/ \________________
287bb501f4SAndreas Klinger */
297bb501f4SAndreas Klinger #include <linux/err.h>
307bb501f4SAndreas Klinger #include <linux/gpio/consumer.h>
317bb501f4SAndreas Klinger #include <linux/kernel.h>
3287b7b07bSAndy Shevchenko #include <linux/mod_devicetable.h>
337bb501f4SAndreas Klinger #include <linux/module.h>
347bb501f4SAndreas Klinger #include <linux/platform_device.h>
357bb501f4SAndreas Klinger #include <linux/property.h>
367bb501f4SAndreas Klinger #include <linux/sched.h>
377bb501f4SAndreas Klinger #include <linux/interrupt.h>
387bb501f4SAndreas Klinger #include <linux/delay.h>
397bb501f4SAndreas Klinger #include <linux/iio/iio.h>
407bb501f4SAndreas Klinger #include <linux/iio/sysfs.h>
417bb501f4SAndreas Klinger
427bb501f4SAndreas Klinger struct ping_cfg {
437bb501f4SAndreas Klinger unsigned long trigger_pulse_us; /* length of trigger pulse */
447bb501f4SAndreas Klinger int laserping_error; /* support error code in */
457bb501f4SAndreas Klinger /* pulse width of laser */
467bb501f4SAndreas Klinger /* ping sensors */
477bb501f4SAndreas Klinger s64 timeout_ns; /* timeout in ns */
487bb501f4SAndreas Klinger };
497bb501f4SAndreas Klinger
507bb501f4SAndreas Klinger struct ping_data {
517bb501f4SAndreas Klinger struct device *dev;
527bb501f4SAndreas Klinger struct gpio_desc *gpiod_ping;
537bb501f4SAndreas Klinger struct mutex lock;
547bb501f4SAndreas Klinger int irqnr;
557bb501f4SAndreas Klinger ktime_t ts_rising;
567bb501f4SAndreas Klinger ktime_t ts_falling;
577bb501f4SAndreas Klinger struct completion rising;
587bb501f4SAndreas Klinger struct completion falling;
597bb501f4SAndreas Klinger const struct ping_cfg *cfg;
607bb501f4SAndreas Klinger };
617bb501f4SAndreas Klinger
627bb501f4SAndreas Klinger static const struct ping_cfg pa_ping_cfg = {
637bb501f4SAndreas Klinger .trigger_pulse_us = 5,
647bb501f4SAndreas Klinger .laserping_error = 0,
657bb501f4SAndreas Klinger .timeout_ns = 18500000, /* 3 meters */
667bb501f4SAndreas Klinger };
677bb501f4SAndreas Klinger
687bb501f4SAndreas Klinger static const struct ping_cfg pa_laser_ping_cfg = {
697bb501f4SAndreas Klinger .trigger_pulse_us = 5,
707bb501f4SAndreas Klinger .laserping_error = 1,
717bb501f4SAndreas Klinger .timeout_ns = 15500000, /* 2 meters plus error codes */
727bb501f4SAndreas Klinger };
737bb501f4SAndreas Klinger
ping_handle_irq(int irq,void * dev_id)747bb501f4SAndreas Klinger static irqreturn_t ping_handle_irq(int irq, void *dev_id)
757bb501f4SAndreas Klinger {
767bb501f4SAndreas Klinger struct iio_dev *indio_dev = dev_id;
777bb501f4SAndreas Klinger struct ping_data *data = iio_priv(indio_dev);
787bb501f4SAndreas Klinger ktime_t now = ktime_get();
797bb501f4SAndreas Klinger
807bb501f4SAndreas Klinger if (gpiod_get_value(data->gpiod_ping)) {
817bb501f4SAndreas Klinger data->ts_rising = now;
827bb501f4SAndreas Klinger complete(&data->rising);
837bb501f4SAndreas Klinger } else {
847bb501f4SAndreas Klinger data->ts_falling = now;
857bb501f4SAndreas Klinger complete(&data->falling);
867bb501f4SAndreas Klinger }
877bb501f4SAndreas Klinger
887bb501f4SAndreas Klinger return IRQ_HANDLED;
897bb501f4SAndreas Klinger }
907bb501f4SAndreas Klinger
ping_read(struct iio_dev * indio_dev)911ecca8a9SAlexandru Ardelean static int ping_read(struct iio_dev *indio_dev)
927bb501f4SAndreas Klinger {
931ecca8a9SAlexandru Ardelean struct ping_data *data = iio_priv(indio_dev);
947bb501f4SAndreas Klinger int ret;
957bb501f4SAndreas Klinger ktime_t ktime_dt;
967bb501f4SAndreas Klinger s64 dt_ns;
977bb501f4SAndreas Klinger u32 time_ns, distance_mm;
987bb501f4SAndreas Klinger struct platform_device *pdev = to_platform_device(data->dev);
997bb501f4SAndreas Klinger
1007bb501f4SAndreas Klinger /*
1017bb501f4SAndreas Klinger * just one read-echo-cycle can take place at a time
1027bb501f4SAndreas Klinger * ==> lock against concurrent reading calls
1037bb501f4SAndreas Klinger */
1047bb501f4SAndreas Klinger mutex_lock(&data->lock);
1057bb501f4SAndreas Klinger
1067bb501f4SAndreas Klinger reinit_completion(&data->rising);
1077bb501f4SAndreas Klinger reinit_completion(&data->falling);
1087bb501f4SAndreas Klinger
1097bb501f4SAndreas Klinger gpiod_set_value(data->gpiod_ping, 1);
1107bb501f4SAndreas Klinger udelay(data->cfg->trigger_pulse_us);
1117bb501f4SAndreas Klinger gpiod_set_value(data->gpiod_ping, 0);
1127bb501f4SAndreas Klinger
1137bb501f4SAndreas Klinger ret = gpiod_direction_input(data->gpiod_ping);
1147bb501f4SAndreas Klinger if (ret < 0) {
1157bb501f4SAndreas Klinger mutex_unlock(&data->lock);
1167bb501f4SAndreas Klinger return ret;
1177bb501f4SAndreas Klinger }
1187bb501f4SAndreas Klinger
1197bb501f4SAndreas Klinger data->irqnr = gpiod_to_irq(data->gpiod_ping);
1207bb501f4SAndreas Klinger if (data->irqnr < 0) {
1217bb501f4SAndreas Klinger dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr);
1227bb501f4SAndreas Klinger mutex_unlock(&data->lock);
1237bb501f4SAndreas Klinger return data->irqnr;
1247bb501f4SAndreas Klinger }
1257bb501f4SAndreas Klinger
1267bb501f4SAndreas Klinger ret = request_irq(data->irqnr, ping_handle_irq,
1277bb501f4SAndreas Klinger IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
1287bb501f4SAndreas Klinger pdev->name, indio_dev);
1297bb501f4SAndreas Klinger if (ret < 0) {
1307bb501f4SAndreas Klinger dev_err(data->dev, "request_irq: %d\n", ret);
1317bb501f4SAndreas Klinger mutex_unlock(&data->lock);
1327bb501f4SAndreas Klinger return ret;
1337bb501f4SAndreas Klinger }
1347bb501f4SAndreas Klinger
1357bb501f4SAndreas Klinger /* it should not take more than 20 ms until echo is rising */
1367bb501f4SAndreas Klinger ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);
1377bb501f4SAndreas Klinger if (ret < 0)
1387bb501f4SAndreas Klinger goto err_reset_direction;
1397bb501f4SAndreas Klinger else if (ret == 0) {
1407bb501f4SAndreas Klinger ret = -ETIMEDOUT;
1417bb501f4SAndreas Klinger goto err_reset_direction;
1427bb501f4SAndreas Klinger }
1437bb501f4SAndreas Klinger
1447bb501f4SAndreas Klinger /* it cannot take more than 50 ms until echo is falling */
1457bb501f4SAndreas Klinger ret = wait_for_completion_killable_timeout(&data->falling, HZ/20);
1467bb501f4SAndreas Klinger if (ret < 0)
1477bb501f4SAndreas Klinger goto err_reset_direction;
1487bb501f4SAndreas Klinger else if (ret == 0) {
1497bb501f4SAndreas Klinger ret = -ETIMEDOUT;
1507bb501f4SAndreas Klinger goto err_reset_direction;
1517bb501f4SAndreas Klinger }
1527bb501f4SAndreas Klinger
1537bb501f4SAndreas Klinger ktime_dt = ktime_sub(data->ts_falling, data->ts_rising);
1547bb501f4SAndreas Klinger
1557bb501f4SAndreas Klinger free_irq(data->irqnr, indio_dev);
1567bb501f4SAndreas Klinger
1577bb501f4SAndreas Klinger ret = gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW);
1587bb501f4SAndreas Klinger if (ret < 0) {
1597bb501f4SAndreas Klinger mutex_unlock(&data->lock);
1607bb501f4SAndreas Klinger return ret;
1617bb501f4SAndreas Klinger }
1627bb501f4SAndreas Klinger
1637bb501f4SAndreas Klinger mutex_unlock(&data->lock);
1647bb501f4SAndreas Klinger
1657bb501f4SAndreas Klinger dt_ns = ktime_to_ns(ktime_dt);
1667bb501f4SAndreas Klinger if (dt_ns > data->cfg->timeout_ns) {
1677bb501f4SAndreas Klinger dev_dbg(data->dev, "distance out of range: dt=%lldns\n",
1687bb501f4SAndreas Klinger dt_ns);
1697bb501f4SAndreas Klinger return -EIO;
1707bb501f4SAndreas Klinger }
1717bb501f4SAndreas Klinger
1727bb501f4SAndreas Klinger time_ns = dt_ns;
1737bb501f4SAndreas Klinger
1747bb501f4SAndreas Klinger /*
1757bb501f4SAndreas Klinger * read error code of laser ping sensor and give users chance to
176*b4b93677SJulia Lawall * figure out error by using dynamic debugging
1777bb501f4SAndreas Klinger */
1787bb501f4SAndreas Klinger if (data->cfg->laserping_error) {
1797bb501f4SAndreas Klinger if ((time_ns > 12500000) && (time_ns <= 13500000)) {
1807bb501f4SAndreas Klinger dev_dbg(data->dev, "target too close or to far\n");
1817bb501f4SAndreas Klinger return -EIO;
1827bb501f4SAndreas Klinger }
1837bb501f4SAndreas Klinger if ((time_ns > 13500000) && (time_ns <= 14500000)) {
1847bb501f4SAndreas Klinger dev_dbg(data->dev, "internal sensor error\n");
1857bb501f4SAndreas Klinger return -EIO;
1867bb501f4SAndreas Klinger }
1877bb501f4SAndreas Klinger if ((time_ns > 14500000) && (time_ns <= 15500000)) {
1887bb501f4SAndreas Klinger dev_dbg(data->dev, "internal sensor timeout\n");
1897bb501f4SAndreas Klinger return -EIO;
1907bb501f4SAndreas Klinger }
1917bb501f4SAndreas Klinger }
1927bb501f4SAndreas Klinger
1937bb501f4SAndreas Klinger /*
1947bb501f4SAndreas Klinger * the speed as function of the temperature is approximately:
1957bb501f4SAndreas Klinger *
1967bb501f4SAndreas Klinger * speed = 331,5 + 0,6 * Temp
1977bb501f4SAndreas Klinger * with Temp in °C
1987bb501f4SAndreas Klinger * and speed in m/s
1997bb501f4SAndreas Klinger *
2007bb501f4SAndreas Klinger * use 343,5 m/s as ultrasonic speed at 20 °C here in absence of the
2017bb501f4SAndreas Klinger * temperature
2027bb501f4SAndreas Klinger *
2037bb501f4SAndreas Klinger * therefore:
2047bb501f4SAndreas Klinger * time 343,5 time * 232
2057bb501f4SAndreas Klinger * distance = ------ * ------- = ------------
2067bb501f4SAndreas Klinger * 10^6 2 1350800
2077bb501f4SAndreas Klinger * with time in ns
2087bb501f4SAndreas Klinger * and distance in mm (one way)
2097bb501f4SAndreas Klinger *
2107bb501f4SAndreas Klinger * because we limit to 3 meters the multiplication with 232 just
2117bb501f4SAndreas Klinger * fits into 32 bit
2127bb501f4SAndreas Klinger */
2137bb501f4SAndreas Klinger distance_mm = time_ns * 232 / 1350800;
2147bb501f4SAndreas Klinger
2157bb501f4SAndreas Klinger return distance_mm;
2167bb501f4SAndreas Klinger
2177bb501f4SAndreas Klinger err_reset_direction:
2187bb501f4SAndreas Klinger free_irq(data->irqnr, indio_dev);
2197bb501f4SAndreas Klinger mutex_unlock(&data->lock);
2207bb501f4SAndreas Klinger
2217bb501f4SAndreas Klinger if (gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW))
2227bb501f4SAndreas Klinger dev_dbg(data->dev, "error in gpiod_direction_output\n");
2237bb501f4SAndreas Klinger return ret;
2247bb501f4SAndreas Klinger }
2257bb501f4SAndreas Klinger
ping_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * channel,int * val,int * val2,long info)2267bb501f4SAndreas Klinger static int ping_read_raw(struct iio_dev *indio_dev,
2277bb501f4SAndreas Klinger struct iio_chan_spec const *channel, int *val,
2287bb501f4SAndreas Klinger int *val2, long info)
2297bb501f4SAndreas Klinger {
2307bb501f4SAndreas Klinger int ret;
2317bb501f4SAndreas Klinger
2327bb501f4SAndreas Klinger if (channel->type != IIO_DISTANCE)
2337bb501f4SAndreas Klinger return -EINVAL;
2347bb501f4SAndreas Klinger
2357bb501f4SAndreas Klinger switch (info) {
2367bb501f4SAndreas Klinger case IIO_CHAN_INFO_RAW:
2371ecca8a9SAlexandru Ardelean ret = ping_read(indio_dev);
2387bb501f4SAndreas Klinger if (ret < 0)
2397bb501f4SAndreas Klinger return ret;
2407bb501f4SAndreas Klinger *val = ret;
2417bb501f4SAndreas Klinger return IIO_VAL_INT;
2427bb501f4SAndreas Klinger case IIO_CHAN_INFO_SCALE:
2437bb501f4SAndreas Klinger /*
2447bb501f4SAndreas Klinger * maximum resolution in datasheet is 1 mm
2457bb501f4SAndreas Klinger * 1 LSB is 1 mm
2467bb501f4SAndreas Klinger */
2477bb501f4SAndreas Klinger *val = 0;
2487bb501f4SAndreas Klinger *val2 = 1000;
2497bb501f4SAndreas Klinger return IIO_VAL_INT_PLUS_MICRO;
2507bb501f4SAndreas Klinger default:
2517bb501f4SAndreas Klinger return -EINVAL;
2527bb501f4SAndreas Klinger }
2537bb501f4SAndreas Klinger }
2547bb501f4SAndreas Klinger
2557bb501f4SAndreas Klinger static const struct iio_info ping_iio_info = {
2567bb501f4SAndreas Klinger .read_raw = ping_read_raw,
2577bb501f4SAndreas Klinger };
2587bb501f4SAndreas Klinger
2597bb501f4SAndreas Klinger static const struct iio_chan_spec ping_chan_spec[] = {
2607bb501f4SAndreas Klinger {
2617bb501f4SAndreas Klinger .type = IIO_DISTANCE,
2627bb501f4SAndreas Klinger .info_mask_separate =
2637bb501f4SAndreas Klinger BIT(IIO_CHAN_INFO_RAW) |
2647bb501f4SAndreas Klinger BIT(IIO_CHAN_INFO_SCALE),
2657bb501f4SAndreas Klinger },
2667bb501f4SAndreas Klinger };
2677bb501f4SAndreas Klinger
2687bb501f4SAndreas Klinger static const struct of_device_id of_ping_match[] = {
2697bb501f4SAndreas Klinger { .compatible = "parallax,ping", .data = &pa_ping_cfg },
27010856d88SYueHaibing { .compatible = "parallax,laserping", .data = &pa_laser_ping_cfg },
2717bb501f4SAndreas Klinger {},
2727bb501f4SAndreas Klinger };
2737bb501f4SAndreas Klinger
2747bb501f4SAndreas Klinger MODULE_DEVICE_TABLE(of, of_ping_match);
2757bb501f4SAndreas Klinger
ping_probe(struct platform_device * pdev)2767bb501f4SAndreas Klinger static int ping_probe(struct platform_device *pdev)
2777bb501f4SAndreas Klinger {
2787bb501f4SAndreas Klinger struct device *dev = &pdev->dev;
2797bb501f4SAndreas Klinger struct ping_data *data;
2807bb501f4SAndreas Klinger struct iio_dev *indio_dev;
2817bb501f4SAndreas Klinger
2827bb501f4SAndreas Klinger indio_dev = devm_iio_device_alloc(dev, sizeof(struct ping_data));
2837bb501f4SAndreas Klinger if (!indio_dev) {
2847bb501f4SAndreas Klinger dev_err(dev, "failed to allocate IIO device\n");
2857bb501f4SAndreas Klinger return -ENOMEM;
2867bb501f4SAndreas Klinger }
2877bb501f4SAndreas Klinger
2887bb501f4SAndreas Klinger data = iio_priv(indio_dev);
2897bb501f4SAndreas Klinger data->dev = dev;
29087b7b07bSAndy Shevchenko data->cfg = device_get_match_data(dev);
2917bb501f4SAndreas Klinger
2927bb501f4SAndreas Klinger mutex_init(&data->lock);
2937bb501f4SAndreas Klinger init_completion(&data->rising);
2947bb501f4SAndreas Klinger init_completion(&data->falling);
2957bb501f4SAndreas Klinger
2967bb501f4SAndreas Klinger data->gpiod_ping = devm_gpiod_get(dev, "ping", GPIOD_OUT_LOW);
2977bb501f4SAndreas Klinger if (IS_ERR(data->gpiod_ping)) {
2987bb501f4SAndreas Klinger dev_err(dev, "failed to get ping-gpios: err=%ld\n",
2997bb501f4SAndreas Klinger PTR_ERR(data->gpiod_ping));
3007bb501f4SAndreas Klinger return PTR_ERR(data->gpiod_ping);
3017bb501f4SAndreas Klinger }
3027bb501f4SAndreas Klinger
3037bb501f4SAndreas Klinger if (gpiod_cansleep(data->gpiod_ping)) {
3047bb501f4SAndreas Klinger dev_err(data->dev, "cansleep-GPIOs not supported\n");
3057bb501f4SAndreas Klinger return -ENODEV;
3067bb501f4SAndreas Klinger }
3077bb501f4SAndreas Klinger
3087bb501f4SAndreas Klinger platform_set_drvdata(pdev, indio_dev);
3097bb501f4SAndreas Klinger
3107bb501f4SAndreas Klinger indio_dev->name = "ping";
3117bb501f4SAndreas Klinger indio_dev->info = &ping_iio_info;
3127bb501f4SAndreas Klinger indio_dev->modes = INDIO_DIRECT_MODE;
3137bb501f4SAndreas Klinger indio_dev->channels = ping_chan_spec;
3147bb501f4SAndreas Klinger indio_dev->num_channels = ARRAY_SIZE(ping_chan_spec);
3157bb501f4SAndreas Klinger
3167bb501f4SAndreas Klinger return devm_iio_device_register(dev, indio_dev);
3177bb501f4SAndreas Klinger }
3187bb501f4SAndreas Klinger
3197bb501f4SAndreas Klinger static struct platform_driver ping_driver = {
3207bb501f4SAndreas Klinger .probe = ping_probe,
3217bb501f4SAndreas Klinger .driver = {
3227bb501f4SAndreas Klinger .name = "ping-gpio",
3237bb501f4SAndreas Klinger .of_match_table = of_ping_match,
3247bb501f4SAndreas Klinger },
3257bb501f4SAndreas Klinger };
3267bb501f4SAndreas Klinger
3277bb501f4SAndreas Klinger module_platform_driver(ping_driver);
3287bb501f4SAndreas Klinger
3297bb501f4SAndreas Klinger MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
3307bb501f4SAndreas Klinger MODULE_DESCRIPTION("PING sensors for distance measuring using one GPIOs");
3317bb501f4SAndreas Klinger MODULE_LICENSE("GPL");
3327bb501f4SAndreas Klinger MODULE_ALIAS("platform:ping");
333