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linux/drivers/iio/proximity/ping.c

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// 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 iio_dev *indio_dev)
{
struct ping_data *data = iio_priv(indio_dev);
int ret;
ktime_t ktime_dt;
s64 dt_ns;
u32 time_ns, distance_mm;
struct platform_device *pdev = to_platform_device(data->dev);
/*
* 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)
{
int ret;
if (channel->type != IIO_DISTANCE)
return -EINVAL;
switch (info) {
case IIO_CHAN_INFO_RAW:
ret = ping_read(indio_dev);
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_laser_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->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");
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