--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PING: ultrasonic sensor for distance measuring by using only one GPIOs
+ *
+ * Copyright (c) 2019 Andreas Klinger <ak@it-klinger.de>
+ *
+ * For details about the devices see:
+ * http://parallax.com/sites/default/files/downloads/28041-LaserPING-2m-Rangefinder-Guide.pdf
+ * http://parallax.com/sites/default/files/downloads/28015-PING-Documentation-v1.6.pdf
+ *
+ * the measurement cycle as timing diagram looks like:
+ *
+ * GPIO ___ ________________________
+ * ping: __/ \____________/ \________________
+ * ^ ^ ^ ^
+ * |<->| interrupt interrupt
+ * udelay(5) (ts_rising) (ts_falling)
+ * |<---------------------->|
+ * . pulse time measured .
+ * . --> one round trip of ultra sonic waves
+ * ultra . .
+ * sonic _ _ _. .
+ * burst: _________/ \_/ \_/ \_________________________________________
+ * .
+ * ultra .
+ * sonic _ _ _.
+ * echo: __________________________________/ \_/ \_/ \________________
+ */
+#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 ping_cfg {
+ unsigned long trigger_pulse_us; /* length of trigger pulse */
+ int laserping_error; /* support error code in */
+ /* pulse width of laser */
+ /* ping sensors */
+ s64 timeout_ns; /* timeout in ns */
+};
+
+struct ping_data {
+ struct device *dev;
+ struct gpio_desc *gpiod_ping;
+ struct mutex lock;
+ int irqnr;
+ ktime_t ts_rising;
+ ktime_t ts_falling;
+ struct completion rising;
+ struct completion falling;
+ const struct ping_cfg *cfg;
+};
+
+static const struct ping_cfg pa_ping_cfg = {
+ .trigger_pulse_us = 5,
+ .laserping_error = 0,
+ .timeout_ns = 18500000, /* 3 meters */
+};
+
+static const struct ping_cfg pa_laser_ping_cfg = {
+ .trigger_pulse_us = 5,
+ .laserping_error = 1,
+ .timeout_ns = 15500000, /* 2 meters plus error codes */
+};
+
+static irqreturn_t ping_handle_irq(int irq, void *dev_id)
+{
+ struct iio_dev *indio_dev = dev_id;
+ struct ping_data *data = iio_priv(indio_dev);
+ ktime_t now = ktime_get();
+
+ if (gpiod_get_value(data->gpiod_ping)) {
+ data->ts_rising = now;
+ complete(&data->rising);
+ } else {
+ data->ts_falling = now;
+ complete(&data->falling);
+ }
+
+ return IRQ_HANDLED;
+}
+
+static int ping_read(struct ping_data *data)
+{
+ int ret;
+ ktime_t ktime_dt;
+ s64 dt_ns;
+ u32 time_ns, distance_mm;
+ struct platform_device *pdev = to_platform_device(data->dev);
+ struct iio_dev *indio_dev = iio_priv_to_dev(data);
+
+ /*
+ * 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_ping, 1);
+ udelay(data->cfg->trigger_pulse_us);
+ gpiod_set_value(data->gpiod_ping, 0);
+
+ ret = gpiod_direction_input(data->gpiod_ping);
+ if (ret < 0) {
+ mutex_unlock(&data->lock);
+ return ret;
+ }
+
+ data->irqnr = gpiod_to_irq(data->gpiod_ping);
+ if (data->irqnr < 0) {
+ dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr);
+ mutex_unlock(&data->lock);
+ return data->irqnr;
+ }
+
+ ret = request_irq(data->irqnr, ping_handle_irq,
+ IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+ pdev->name, indio_dev);
+ if (ret < 0) {
+ dev_err(data->dev, "request_irq: %d\n", ret);
+ mutex_unlock(&data->lock);
+ return ret;
+ }
+
+ /* 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)
+ goto err_reset_direction;
+ else if (ret == 0) {
+ ret = -ETIMEDOUT;
+ goto err_reset_direction;
+ }
+
+ /* it cannot take more than 50 ms until echo is falling */
+ ret = wait_for_completion_killable_timeout(&data->falling, HZ/20);
+ if (ret < 0)
+ goto err_reset_direction;
+ else if (ret == 0) {
+ ret = -ETIMEDOUT;
+ goto err_reset_direction;
+ }
+
+ ktime_dt = ktime_sub(data->ts_falling, data->ts_rising);
+
+ free_irq(data->irqnr, indio_dev);
+
+ ret = gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW);
+ if (ret < 0) {
+ mutex_unlock(&data->lock);
+ return ret;
+ }
+
+ mutex_unlock(&data->lock);
+
+ dt_ns = ktime_to_ns(ktime_dt);
+ if (dt_ns > data->cfg->timeout_ns) {
+ dev_dbg(data->dev, "distance out of range: dt=%lldns\n",
+ dt_ns);
+ return -EIO;
+ }
+
+ time_ns = dt_ns;
+
+ /*
+ * read error code of laser ping sensor and give users chance to
+ * figure out error by using dynamic debuggging
+ */
+ if (data->cfg->laserping_error) {
+ if ((time_ns > 12500000) && (time_ns <= 13500000)) {
+ dev_dbg(data->dev, "target too close or to far\n");
+ return -EIO;
+ }
+ if ((time_ns > 13500000) && (time_ns <= 14500000)) {
+ dev_dbg(data->dev, "internal sensor error\n");
+ return -EIO;
+ }
+ if ((time_ns > 14500000) && (time_ns <= 15500000)) {
+ dev_dbg(data->dev, "internal sensor timeout\n");
+ return -EIO;
+ }
+ }
+
+ /*
+ * 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 * 232
+ * distance = ------ * ------- = ------------
+ * 10^6 2 1350800
+ * with time in ns
+ * and distance in mm (one way)
+ *
+ * because we limit to 3 meters the multiplication with 232 just
+ * fits into 32 bit
+ */
+ distance_mm = time_ns * 232 / 1350800;
+
+ return distance_mm;
+
+err_reset_direction:
+ free_irq(data->irqnr, indio_dev);
+ mutex_unlock(&data->lock);
+
+ if (gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW))
+ dev_dbg(data->dev, "error in gpiod_direction_output\n");
+ return ret;
+}
+
+static int ping_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *channel, int *val,
+ int *val2, long info)
+{
+ struct ping_data *data = iio_priv(indio_dev);
+ int ret;
+
+ if (channel->type != IIO_DISTANCE)
+ return -EINVAL;
+
+ switch (info) {
+ case IIO_CHAN_INFO_RAW:
+ ret = ping_read(data);
+ if (ret < 0)
+ return ret;
+ *val = ret;
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ /*
+ * maximum resolution in datasheet is 1 mm
+ * 1 LSB is 1 mm
+ */
+ *val = 0;
+ *val2 = 1000;
+ return IIO_VAL_INT_PLUS_MICRO;
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_info ping_iio_info = {
+ .read_raw = ping_read_raw,
+};
+
+static const struct iio_chan_spec ping_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_ping_match[] = {
+ { .compatible = "parallax,ping", .data = &pa_ping_cfg},
+ { .compatible = "parallax,laserping", .data = &pa_ping_cfg},
+ {},
+};
+
+MODULE_DEVICE_TABLE(of, of_ping_match);
+
+static int ping_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct ping_data *data;
+ struct iio_dev *indio_dev;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(struct ping_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_device_get_match_data(dev);
+
+ mutex_init(&data->lock);
+ init_completion(&data->rising);
+ init_completion(&data->falling);
+
+ data->gpiod_ping = devm_gpiod_get(dev, "ping", GPIOD_OUT_LOW);
+ if (IS_ERR(data->gpiod_ping)) {
+ dev_err(dev, "failed to get ping-gpios: err=%ld\n",
+ PTR_ERR(data->gpiod_ping));
+ return PTR_ERR(data->gpiod_ping);
+ }
+
+ if (gpiod_cansleep(data->gpiod_ping)) {
+ dev_err(data->dev, "cansleep-GPIOs not supported\n");
+ return -ENODEV;
+ }
+
+ platform_set_drvdata(pdev, indio_dev);
+
+ indio_dev->name = "ping";
+ indio_dev->dev.parent = &pdev->dev;
+ indio_dev->info = &ping_iio_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = ping_chan_spec;
+ indio_dev->num_channels = ARRAY_SIZE(ping_chan_spec);
+
+ return devm_iio_device_register(dev, indio_dev);
+}
+
+static struct platform_driver ping_driver = {
+ .probe = ping_probe,
+ .driver = {
+ .name = "ping-gpio",
+ .of_match_table = of_ping_match,
+ },
+};
+
+module_platform_driver(ping_driver);
+
+MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
+MODULE_DESCRIPTION("PING sensors for distance measuring using one GPIOs");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ping");
projects / users / hch / dma-mapping.git / commitdiff