333 lines
8.6 KiB
C
333 lines
8.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* PING: ultrasonic sensor for distance measuring by using only one GPIOs
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*
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* Copyright (c) 2019 Andreas Klinger <ak@it-klinger.de>
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*
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* For details about the devices see:
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* http://parallax.com/sites/default/files/downloads/28041-LaserPING-2m-Rangefinder-Guide.pdf
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* http://parallax.com/sites/default/files/downloads/28015-PING-Documentation-v1.6.pdf
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*
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* the measurement cycle as timing diagram looks like:
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*
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* GPIO ___ ________________________
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* ping: __/ \____________/ \________________
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* ^ ^ ^ ^
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* |<->| interrupt interrupt
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* udelay(5) (ts_rising) (ts_falling)
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* |<---------------------->|
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* . pulse time measured .
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* . --> one round trip of ultra sonic waves
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* ultra . .
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* sonic _ _ _. .
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* burst: _________/ \_/ \_/ \_________________________________________
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* .
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* ultra .
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* sonic _ _ _.
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* echo: __________________________________/ \_/ \_/ \________________
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*/
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#include <linux/err.h>
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#include <linux/gpio/consumer.h>
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#include <linux/kernel.h>
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#include <linux/mod_devicetable.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/property.h>
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#include <linux/sched.h>
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#include <linux/interrupt.h>
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#include <linux/delay.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/sysfs.h>
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struct ping_cfg {
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unsigned long trigger_pulse_us; /* length of trigger pulse */
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int laserping_error; /* support error code in */
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/* pulse width of laser */
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/* ping sensors */
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s64 timeout_ns; /* timeout in ns */
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};
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struct ping_data {
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struct device *dev;
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struct gpio_desc *gpiod_ping;
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struct mutex lock;
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int irqnr;
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ktime_t ts_rising;
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ktime_t ts_falling;
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struct completion rising;
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struct completion falling;
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const struct ping_cfg *cfg;
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};
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static const struct ping_cfg pa_ping_cfg = {
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.trigger_pulse_us = 5,
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.laserping_error = 0,
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.timeout_ns = 18500000, /* 3 meters */
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};
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static const struct ping_cfg pa_laser_ping_cfg = {
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.trigger_pulse_us = 5,
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.laserping_error = 1,
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.timeout_ns = 15500000, /* 2 meters plus error codes */
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};
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static irqreturn_t ping_handle_irq(int irq, void *dev_id)
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{
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struct iio_dev *indio_dev = dev_id;
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struct ping_data *data = iio_priv(indio_dev);
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ktime_t now = ktime_get();
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if (gpiod_get_value(data->gpiod_ping)) {
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data->ts_rising = now;
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complete(&data->rising);
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} else {
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data->ts_falling = now;
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complete(&data->falling);
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}
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return IRQ_HANDLED;
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}
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static int ping_read(struct iio_dev *indio_dev)
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{
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struct ping_data *data = iio_priv(indio_dev);
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int ret;
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ktime_t ktime_dt;
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s64 dt_ns;
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u32 time_ns, distance_mm;
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struct platform_device *pdev = to_platform_device(data->dev);
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/*
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* just one read-echo-cycle can take place at a time
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* ==> lock against concurrent reading calls
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*/
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mutex_lock(&data->lock);
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reinit_completion(&data->rising);
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reinit_completion(&data->falling);
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gpiod_set_value(data->gpiod_ping, 1);
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udelay(data->cfg->trigger_pulse_us);
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gpiod_set_value(data->gpiod_ping, 0);
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ret = gpiod_direction_input(data->gpiod_ping);
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if (ret < 0) {
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mutex_unlock(&data->lock);
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return ret;
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}
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data->irqnr = gpiod_to_irq(data->gpiod_ping);
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if (data->irqnr < 0) {
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dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr);
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mutex_unlock(&data->lock);
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return data->irqnr;
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}
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ret = request_irq(data->irqnr, ping_handle_irq,
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IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
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pdev->name, indio_dev);
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if (ret < 0) {
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dev_err(data->dev, "request_irq: %d\n", ret);
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mutex_unlock(&data->lock);
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return ret;
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}
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/* it should not take more than 20 ms until echo is rising */
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ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);
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if (ret < 0)
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goto err_reset_direction;
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else if (ret == 0) {
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ret = -ETIMEDOUT;
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goto err_reset_direction;
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}
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/* it cannot take more than 50 ms until echo is falling */
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ret = wait_for_completion_killable_timeout(&data->falling, HZ/20);
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if (ret < 0)
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goto err_reset_direction;
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else if (ret == 0) {
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ret = -ETIMEDOUT;
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goto err_reset_direction;
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}
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ktime_dt = ktime_sub(data->ts_falling, data->ts_rising);
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free_irq(data->irqnr, indio_dev);
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ret = gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW);
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if (ret < 0) {
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mutex_unlock(&data->lock);
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return ret;
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}
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mutex_unlock(&data->lock);
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dt_ns = ktime_to_ns(ktime_dt);
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if (dt_ns > data->cfg->timeout_ns) {
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dev_dbg(data->dev, "distance out of range: dt=%lldns\n",
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dt_ns);
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return -EIO;
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}
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time_ns = dt_ns;
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/*
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* read error code of laser ping sensor and give users chance to
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* figure out error by using dynamic debugging
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*/
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if (data->cfg->laserping_error) {
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if ((time_ns > 12500000) && (time_ns <= 13500000)) {
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dev_dbg(data->dev, "target too close or to far\n");
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return -EIO;
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}
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if ((time_ns > 13500000) && (time_ns <= 14500000)) {
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dev_dbg(data->dev, "internal sensor error\n");
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return -EIO;
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}
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if ((time_ns > 14500000) && (time_ns <= 15500000)) {
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dev_dbg(data->dev, "internal sensor timeout\n");
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return -EIO;
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}
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}
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/*
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* the speed as function of the temperature is approximately:
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*
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* speed = 331,5 + 0,6 * Temp
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* with Temp in °C
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* and speed in m/s
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*
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* use 343,5 m/s as ultrasonic speed at 20 °C here in absence of the
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* temperature
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*
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* therefore:
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* time 343,5 time * 232
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* distance = ------ * ------- = ------------
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* 10^6 2 1350800
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* with time in ns
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* and distance in mm (one way)
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*
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* because we limit to 3 meters the multiplication with 232 just
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* fits into 32 bit
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*/
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distance_mm = time_ns * 232 / 1350800;
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return distance_mm;
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err_reset_direction:
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free_irq(data->irqnr, indio_dev);
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mutex_unlock(&data->lock);
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if (gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW))
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dev_dbg(data->dev, "error in gpiod_direction_output\n");
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return ret;
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}
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static int ping_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *channel, int *val,
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int *val2, long info)
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{
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int ret;
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if (channel->type != IIO_DISTANCE)
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return -EINVAL;
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switch (info) {
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case IIO_CHAN_INFO_RAW:
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ret = ping_read(indio_dev);
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if (ret < 0)
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return ret;
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*val = ret;
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return IIO_VAL_INT;
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case IIO_CHAN_INFO_SCALE:
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/*
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* maximum resolution in datasheet is 1 mm
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* 1 LSB is 1 mm
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*/
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*val = 0;
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*val2 = 1000;
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return IIO_VAL_INT_PLUS_MICRO;
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default:
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return -EINVAL;
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}
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}
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static const struct iio_info ping_iio_info = {
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.read_raw = ping_read_raw,
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};
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static const struct iio_chan_spec ping_chan_spec[] = {
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{
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.type = IIO_DISTANCE,
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.info_mask_separate =
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BIT(IIO_CHAN_INFO_RAW) |
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BIT(IIO_CHAN_INFO_SCALE),
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},
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};
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static const struct of_device_id of_ping_match[] = {
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{ .compatible = "parallax,ping", .data = &pa_ping_cfg },
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{ .compatible = "parallax,laserping", .data = &pa_laser_ping_cfg },
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{},
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};
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MODULE_DEVICE_TABLE(of, of_ping_match);
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static int ping_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct ping_data *data;
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struct iio_dev *indio_dev;
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indio_dev = devm_iio_device_alloc(dev, sizeof(struct ping_data));
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if (!indio_dev) {
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dev_err(dev, "failed to allocate IIO device\n");
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return -ENOMEM;
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}
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data = iio_priv(indio_dev);
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data->dev = dev;
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data->cfg = device_get_match_data(dev);
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mutex_init(&data->lock);
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init_completion(&data->rising);
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init_completion(&data->falling);
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data->gpiod_ping = devm_gpiod_get(dev, "ping", GPIOD_OUT_LOW);
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if (IS_ERR(data->gpiod_ping)) {
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dev_err(dev, "failed to get ping-gpios: err=%ld\n",
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PTR_ERR(data->gpiod_ping));
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return PTR_ERR(data->gpiod_ping);
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}
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if (gpiod_cansleep(data->gpiod_ping)) {
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dev_err(data->dev, "cansleep-GPIOs not supported\n");
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return -ENODEV;
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}
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platform_set_drvdata(pdev, indio_dev);
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indio_dev->name = "ping";
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indio_dev->info = &ping_iio_info;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = ping_chan_spec;
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indio_dev->num_channels = ARRAY_SIZE(ping_chan_spec);
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return devm_iio_device_register(dev, indio_dev);
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}
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static struct platform_driver ping_driver = {
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.probe = ping_probe,
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.driver = {
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.name = "ping-gpio",
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.of_match_table = of_ping_match,
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},
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};
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module_platform_driver(ping_driver);
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MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
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MODULE_DESCRIPTION("PING sensors for distance measuring using one GPIOs");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:ping");
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