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linux/drivers/iio/proximity/srf04.c
Uwe Kleine-König 4abfc97db9 iio: proximity: srf04: Convert to platform remove callback returning void 
The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.
To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new() which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230919174931.1417681-47-u.kleine-koenig@pengutronix.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2023-09-23 15:06:56 +01:00

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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/mod_devicetable.h>
#include <linux/module.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 = device_get_match_data(dev);
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) {
data->startup_time_ms = 100;
device_property_read_u32(dev, "startup-time-ms", &data->startup_time_ms);
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 void 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);
}
}
static int 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 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 = {
RUNTIME_PM_OPS(srf04_pm_runtime_suspend,
srf04_pm_runtime_resume, NULL)
};
static struct platform_driver srf04_driver = {
.probe = srf04_probe,
.remove_new = srf04_remove,
.driver = {
.name = "srf04-gpio",
.of_match_table = of_srf04_match,
.pm = pm_ptr(&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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