On 30/01/17 12:51, Andreas Klinger wrote: > This patch adds support for the ultrasonic ranger srf04 of devantech. > > This device is measuring the distance of objects in a range between 1 cm > and 3 meters and a theoretical resolution of 3 mm. > > There are two GPIOs used: > - trigger: set as output to the device when the measurement should start > - echo: set by the device when the ultrasonic wave is sent out and reset > when the echo is recognized; this needs to be an interrupt input > > The time between setting and resetting the echo pin is the time the > waveform needed for one round trip. This time is recorded in the interrupt > handler. > > The distance is calculated in the read function by using the ultrasonic > speed at 20 degrees celsius which is about 343 m/s. > > Signed-off-by: Andreas Klinger <ak@xxxxxxxxxxxxx> A few minor bits and bobs inline. Nice if somewhat unusual little driver. The ideal using one of these would be to connect them up to a hardware timer to get better precision but obviously they aren't always available. (not to mention we don't have a good framework to handle them when they are!) Jonathan > --- > MAINTAINERS | 6 + > drivers/iio/proximity/Kconfig | 11 ++ > drivers/iio/proximity/Makefile | 1 + > drivers/iio/proximity/srf04.c | 313 +++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 331 insertions(+) > create mode 100644 drivers/iio/proximity/srf04.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index fa6af014fd72..ba979cc48fd8 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -3469,6 +3469,12 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/balbi/usb.git > S: Maintained > F: drivers/usb/dwc3/ > > +DEVANTECH SRF ULTRASONIC RANGER IIO DRIVER > +M: Andreas Klinger <ak@xxxxxxxxxxxxx> > +L: linux-iio@xxxxxxxxxxxxxxx > +S: Maintained > +F: drivers/iio/proximity/srf*.c > + > DEVICE COREDUMP (DEV_COREDUMP) > M: Johannes Berg <johannes@xxxxxxxxxxxxxxxx> > L: linux-kernel@xxxxxxxxxxxxxxx > diff --git a/drivers/iio/proximity/Kconfig b/drivers/iio/proximity/Kconfig > index ef4c73db5b53..0bcbc66eae6e 100644 > --- a/drivers/iio/proximity/Kconfig > +++ b/drivers/iio/proximity/Kconfig > @@ -32,6 +32,17 @@ config LIDAR_LITE_V2 > To compile this driver as a module, choose M here: the > module will be called pulsedlight-lite-v2 > > +config SRF04 > + tristate "Devantech SRF04 ultrasonic ranger sensor" > + depends on GPIOLIB > + help > + Say Y here to build a driver for Devantech SRF04 ultrasonic > + ranger sensor. This driver can be used to measure the distance > + of objects. It is using two GPIOs. > + > + To compile this driver as a module, choose M here: the > + module will be called srf04. > + > config SX9500 > tristate "SX9500 Semtech proximity sensor" > select IIO_BUFFER > diff --git a/drivers/iio/proximity/Makefile b/drivers/iio/proximity/Makefile > index 9aadd9a8ee99..97c046c1dfc5 100644 > --- a/drivers/iio/proximity/Makefile > +++ b/drivers/iio/proximity/Makefile > @@ -5,4 +5,5 @@ > # When adding new entries keep the list in alphabetical order > obj-$(CONFIG_AS3935) += as3935.o > obj-$(CONFIG_LIDAR_LITE_V2) += pulsedlight-lidar-lite-v2.o > +obj-$(CONFIG_SRF04) += srf04.o > obj-$(CONFIG_SX9500) += sx9500.o > diff --git a/drivers/iio/proximity/srf04.c b/drivers/iio/proximity/srf04.c > new file mode 100644 > index 000000000000..2cbb4dd6f175 > --- /dev/null > +++ b/drivers/iio/proximity/srf04.c > @@ -0,0 +1,313 @@ > +/* > + * SRF04: ultrasonic sensor for distance measuring by using GPIOs > + * > + * Copyright (c) 2017 Andreas Klinger <ak@xxxxxxxxxxxxx> > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * For details about the device see: > + * http://www.robot-electronics.co.uk/htm/srf04tech.htm > + * > + * the measurement cycle as timing diagram looks like: > + * > + * +---+ > + * GPIO | | > + * trig: --+ +------------------------------------------------------ > + * ^ ^ > + * |<->| > + * udelay(10) > + * > + * ultra +-+ +-+ +-+ > + * sonic | | | | | | > + * burst: ---------+ +-+ +-+ +----------------------------------------- > + * . > + * ultra . +-+ +-+ +-+ > + * sonic . | | | | | | > + * echo: ----------------------------------+ +-+ +-+ +---------------- > + * . . > + * +------------------------+ > + * GPIO | | > + * echo: -------------------+ +--------------- > + * ^ ^ > + * interrupt interrupt > + * (ts_rising) (ts_falling) > + * |<---------------------->| > + * pulse time measured > + * --> one round trip of ultra sonic waves Nice art work ;) > + */ > +#include <linux/err.h> > +#include <linux/gpio/consumer.h> > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/of.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 srf04_data { > + struct device *dev; > + struct gpio_desc *gpiod_trig; > + struct gpio_desc *gpiod_echo; > + struct mutex lock; > + int irqnr; > + ktime_t ts_rising; > + ktime_t ts_falling; > + struct completion rising; > + struct completion falling; > +}; > + > +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); > + > + if (gpiod_get_value(data->gpiod_echo)) { Why not grab the time first? We can't sleep but we can take a while over getting the gpio value and that time could in theory be variable. > + data->ts_rising = ktime_get(); > + complete(&data->rising); > + } else { > + data->ts_falling = ktime_get(); > + 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; > + > + /* > + * 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(10); > + gpiod_set_value(data->gpiod_trig, 0); > + > + /* it cannot take more than 20 ms */ > + 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; > + } > + > + ret = wait_for_completion_killable_timeout(&data->falling, HZ/50); > + 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 3 meters is beyond the capabilities of > + * the sensor > + * ==> filter out invalid results for not measuring echos of > + * another us sensor > + * > + * formula: > + * distance 3 m > + * time = ---------- = --------- = 9404389 ns > + * speed 319 m/s > + * > + * using a minimum speed at -20 °C of 319 m/s > + */ > + if (dt_ns > 9404389) > + 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 m/s as ultrasonic speed at 20 °C here in absence of the > + * temperature > + * > + * therefore: > + * time 343 > + * distance = ------ * ----- > + * 10^6 2 > + * with time in ns > + * and distance in mm (one way) > + * > + * because we limit to 3 meters the multiplication with 343 just > + * fits into 32 bit > + */ > + distance_mm = time_ns * 343 / 2000000; > + > + 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 = { > + .driver_module = THIS_MODULE, > + .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 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; > + > + 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); > + } > + > + 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->dev.parent = &pdev->dev; > + 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); > + > + return iio_device_register(indio_dev); > +} > + > +static int srf04_remove(struct platform_device *pdev) > +{ > + struct iio_dev *indio_dev = platform_get_drvdata(pdev); > + > + iio_device_unregister(indio_dev); With nothing else in here, you can use devm_iio_device_register and drop the remove entirely. > + > + return 0; > +} > + > +static const struct of_device_id of_srf04_match[] = { > + { .compatible = "devantech,srf04", }, > + {}, > +}; > + > +MODULE_DEVICE_TABLE(of, of_srf04_match); > + > +static struct platform_driver srf04_driver = { > + .probe = srf04_probe, > + .remove = srf04_remove, > + .driver = { > + .name = "srf04-gpio", > + .of_match_table = of_srf04_match, > + }, > +}; > + > +module_platform_driver(srf04_driver); > + > +MODULE_AUTHOR("Andreas Klinger <ak@xxxxxxxxxxxxx>"); > +MODULE_DESCRIPTION("SRF04 ultrasonic sensor for distance measuring using GPIOs"); > +MODULE_LICENSE("GPL"); > +MODULE_ALIAS("platform:srf04"); > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
