334 lines
8.6 KiB
C
334 lines
8.6 KiB
C
// 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");
|