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kernel/drivers/iio/proximity/srf04.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* SRF04: ultrasonic sensor for distance measuring by using GPIOs
*
* Copyright (c) 2017 Andreas Klinger <ak@it-klinger.de>
*
* For details about the device see:
* https://www.robot-electronics.co.uk/htm/srf04tech.htm
*
* the measurement cycle as timing diagram looks like:
*
* +---+
* GPIO | |
* trig: --+ +------------------------------------------------------
* ^ ^
* |<->|
* udelay(trigger_pulse_us)
*
* ultra +-+ +-+ +-+
* sonic | | | | | |
* burst: ---------+ +-+ +-+ +-----------------------------------------
* .
* ultra . +-+ +-+ +-+
* sonic . | | | | | |
* echo: ----------------------------------+ +-+ +-+ +----------------
* . .
* +------------------------+
* GPIO | |
* echo: -------------------+ +---------------
* ^ ^
* interrupt interrupt
* (ts_rising) (ts_falling)
* |<---------------------->|
* pulse time measured
* --> one round trip of ultra sonic waves
*/
#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/pm_runtime.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
struct srf04_cfg {
unsigned long trigger_pulse_us;
};
struct srf04_data {
struct device *dev;
struct gpio_desc *gpiod_trig;
struct gpio_desc *gpiod_echo;
struct gpio_desc *gpiod_power;
struct mutex lock;
int irqnr;
ktime_t ts_rising;
ktime_t ts_falling;
struct completion rising;
struct completion falling;
const struct srf04_cfg *cfg;
int startup_time_ms;
};
static const struct srf04_cfg srf04_cfg = {
.trigger_pulse_us = 10,
};
static const struct srf04_cfg mb_lv_cfg = {
.trigger_pulse_us = 20,
};
static irqreturn_t srf04_handle_irq(int irq, void *dev_id)
{
struct iio_dev *indio_dev = dev_id;
struct srf04_data *data = iio_priv(indio_dev);
ktime_t now = ktime_get();
if (gpiod_get_value(data->gpiod_echo)) {
data->ts_rising = now;
complete(&data->rising);
} else {
data->ts_falling = now;
complete(&data->falling);
}
return IRQ_HANDLED;
}
static int srf04_read(struct srf04_data *data)
{
int ret;
ktime_t ktime_dt;
u64 dt_ns;
u32 time_ns, distance_mm;
if (data->gpiod_power) {
ret = pm_runtime_resume_and_get(data->dev);
if (ret < 0)
return ret;
}
/*
* 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_trig, 1);
udelay(data->cfg->trigger_pulse_us);
gpiod_set_value(data->gpiod_trig, 0);
if (data->gpiod_power) {
pm_runtime_mark_last_busy(data->dev);
pm_runtime_put_autosuspend(data->dev);
}
/* 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) {
mutex_unlock(&data->lock);
return ret;
} else if (ret == 0) {
mutex_unlock(&data->lock);
return -ETIMEDOUT;
}
/* it cannot take more than 50 ms until echo is falling */
ret = wait_for_completion_killable_timeout(&data->falling, HZ/20);
if (ret < 0) {
mutex_unlock(&data->lock);
return ret;
} else if (ret == 0) {
mutex_unlock(&data->lock);
return -ETIMEDOUT;
}
ktime_dt = ktime_sub(data->ts_falling, data->ts_rising);
mutex_unlock(&data->lock);
dt_ns = ktime_to_ns(ktime_dt);
/*
* measuring more than 6,45 meters is beyond the capabilities of
* the supported sensors
* ==> filter out invalid results for not measuring echos of
* another us sensor
*
* formula:
* distance 6,45 * 2 m
* time = ---------- = ------------ = 40438871 ns
* speed 319 m/s
*
* using a minimum speed at -20 °C of 319 m/s
*/
if (dt_ns > 40438871)
return -EIO;
time_ns = dt_ns;
/*
* 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 * 106
* distance = ------ * ------- = ------------
* 10^6 2 617176
* with time in ns
* and distance in mm (one way)
*
* because we limit to 6,45 meters the multiplication with 106 just
* fits into 32 bit
*/
distance_mm = time_ns * 106 / 617176;
return distance_mm;
}
static int srf04_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *channel, int *val,
int *val2, long info)
{
struct srf04_data *data = iio_priv(indio_dev);
int ret;
if (channel->type != IIO_DISTANCE)
return -EINVAL;
switch (info) {
case IIO_CHAN_INFO_RAW:
ret = srf04_read(data);
if (ret < 0)
return ret;
*val = ret;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
/*
* theoretical maximum resolution is 3 mm
* 1 LSB is 1 mm
*/
*val = 0;
*val2 = 1000;
return IIO_VAL_INT_PLUS_MICRO;
default:
return -EINVAL;
}
}
static const struct iio_info srf04_iio_info = {
.read_raw = srf04_read_raw,
};
static const struct iio_chan_spec srf04_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_srf04_match[] = {
{ .compatible = "devantech,srf04", .data = &srf04_cfg },
{ .compatible = "maxbotix,mb1000", .data = &mb_lv_cfg },
{ .compatible = "maxbotix,mb1010", .data = &mb_lv_cfg },
{ .compatible = "maxbotix,mb1020", .data = &mb_lv_cfg },
{ .compatible = "maxbotix,mb1030", .data = &mb_lv_cfg },
{ .compatible = "maxbotix,mb1040", .data = &mb_lv_cfg },
{},
};
MODULE_DEVICE_TABLE(of, of_srf04_match);
static int srf04_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct srf04_data *data;
struct iio_dev *indio_dev;
int ret;
indio_dev = devm_iio_device_alloc(dev, sizeof(struct srf04_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_match_device(of_srf04_match, dev)->data;
mutex_init(&data->lock);
init_completion(&data->rising);
init_completion(&data->falling);
data->gpiod_trig = devm_gpiod_get(dev, "trig", GPIOD_OUT_LOW);
if (IS_ERR(data->gpiod_trig)) {
dev_err(dev, "failed to get trig-gpios: err=%ld\n",
PTR_ERR(data->gpiod_trig));
return PTR_ERR(data->gpiod_trig);
}
data->gpiod_echo = devm_gpiod_get(dev, "echo", GPIOD_IN);
if (IS_ERR(data->gpiod_echo)) {
dev_err(dev, "failed to get echo-gpios: err=%ld\n",
PTR_ERR(data->gpiod_echo));
return PTR_ERR(data->gpiod_echo);
}
data->gpiod_power = devm_gpiod_get_optional(dev, "power",
GPIOD_OUT_LOW);
if (IS_ERR(data->gpiod_power)) {
dev_err(dev, "failed to get power-gpios: err=%ld\n",
PTR_ERR(data->gpiod_power));
return PTR_ERR(data->gpiod_power);
}
if (data->gpiod_power) {
if (of_property_read_u32(dev->of_node, "startup-time-ms",
&data->startup_time_ms))
data->startup_time_ms = 100;
dev_dbg(dev, "using power gpio: startup-time-ms=%d\n",
data->startup_time_ms);
}
if (gpiod_cansleep(data->gpiod_echo)) {
dev_err(data->dev, "cansleep-GPIOs not supported\n");
return -ENODEV;
}
data->irqnr = gpiod_to_irq(data->gpiod_echo);
if (data->irqnr < 0) {
dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr);
return data->irqnr;
}
ret = devm_request_irq(dev, data->irqnr, srf04_handle_irq,
IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
pdev->name, indio_dev);
if (ret < 0) {
dev_err(data->dev, "request_irq: %d\n", ret);
return ret;
}
platform_set_drvdata(pdev, indio_dev);
indio_dev->name = "srf04";
indio_dev->info = &srf04_iio_info;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = srf04_chan_spec;
indio_dev->num_channels = ARRAY_SIZE(srf04_chan_spec);
ret = iio_device_register(indio_dev);
if (ret < 0) {
dev_err(data->dev, "iio_device_register: %d\n", ret);
return ret;
}
if (data->gpiod_power) {
pm_runtime_set_autosuspend_delay(data->dev, 1000);
pm_runtime_use_autosuspend(data->dev);
ret = pm_runtime_set_active(data->dev);
if (ret) {
dev_err(data->dev, "pm_runtime_set_active: %d\n", ret);
iio_device_unregister(indio_dev);
}
pm_runtime_enable(data->dev);
pm_runtime_idle(data->dev);
}
return ret;
}
static int srf04_remove(struct platform_device *pdev)
{
struct iio_dev *indio_dev = platform_get_drvdata(pdev);
struct srf04_data *data = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
if (data->gpiod_power) {
pm_runtime_disable(data->dev);
pm_runtime_set_suspended(data->dev);
}
return 0;
}
static int __maybe_unused srf04_pm_runtime_suspend(struct device *dev)
{
struct platform_device *pdev = container_of(dev,
struct platform_device, dev);
struct iio_dev *indio_dev = platform_get_drvdata(pdev);
struct srf04_data *data = iio_priv(indio_dev);
gpiod_set_value(data->gpiod_power, 0);
return 0;
}
static int __maybe_unused srf04_pm_runtime_resume(struct device *dev)
{
struct platform_device *pdev = container_of(dev,
struct platform_device, dev);
struct iio_dev *indio_dev = platform_get_drvdata(pdev);
struct srf04_data *data = iio_priv(indio_dev);
gpiod_set_value(data->gpiod_power, 1);
msleep(data->startup_time_ms);
return 0;
}
static const struct dev_pm_ops srf04_pm_ops = {
SET_RUNTIME_PM_OPS(srf04_pm_runtime_suspend,
srf04_pm_runtime_resume, NULL)
};
static struct platform_driver srf04_driver = {
.probe = srf04_probe,
.remove = srf04_remove,
.driver = {
.name = "srf04-gpio",
.of_match_table = of_srf04_match,
.pm = &srf04_pm_ops,
},
};
module_platform_driver(srf04_driver);
MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
MODULE_DESCRIPTION("SRF04 ultrasonic sensor for distance measuring using GPIOs");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:srf04");
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