From: Johannes Thoma <johannes@xxxxxxxxxxxxxxxxx> The HC-SR04 is an ultrasonic distance sensor attached to two GPIO pins. The driver is based on the Industrial I/O (iio) subsystem and is controlled via configfs and sysfs. It supports an (in theory) unlimited number of HC-SR04 devices. A datasheet to the device can be found at: http://www.micropik.com/PDF/HCSR04.pdf Signed-off-by: Johannes Thoma <johannes@xxxxxxxxxxxxxxxxx> --- MAINTAINERS | 7 + drivers/iio/Kconfig | 1 + drivers/iio/Makefile | 1 + drivers/iio/ultrasonic-distance/Kconfig | 17 ++ drivers/iio/ultrasonic-distance/Makefile | 6 + drivers/iio/ultrasonic-distance/hc-sr04.c | 466 ++++++++++++++++++++++++++++++ 6 files changed, 498 insertions(+) create mode 100644 drivers/iio/ultrasonic-distance/Kconfig create mode 100644 drivers/iio/ultrasonic-distance/Makefile create mode 100644 drivers/iio/ultrasonic-distance/hc-sr04.c diff --git a/MAINTAINERS b/MAINTAINERS index 7304d2e..3bd640e 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -5211,6 +5211,13 @@ W: http://www.kernel.org/pub/linux/kernel/people/fseidel/hdaps/ S: Maintained F: drivers/platform/x86/hdaps.c + +HC-SR04 ULTRASONIC DISTANCE SENSOR DRIVER +M: Johannes Thoma <johannes@xxxxxxxxxxxxxxxxx> +S: Maintained +F: drivers/iio/ultrasonic-distance/hc-sr04.c + + HDPVR USB VIDEO ENCODER DRIVER M: Hans Verkuil <hverkuil@xxxxxxxxx> L: linux-media@xxxxxxxxxxxxxxx diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig index 505e921..3c82aad 100644 --- a/drivers/iio/Kconfig +++ b/drivers/iio/Kconfig @@ -82,5 +82,6 @@ source "drivers/iio/potentiometer/Kconfig" source "drivers/iio/pressure/Kconfig" source "drivers/iio/proximity/Kconfig" source "drivers/iio/temperature/Kconfig" +source "drivers/iio/ultrasonic-distance/Kconfig" endif # IIO diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile index 20f6490..0f1c00c 100644 --- a/drivers/iio/Makefile +++ b/drivers/iio/Makefile @@ -32,3 +32,4 @@ obj-y += pressure/ obj-y += proximity/ obj-y += temperature/ obj-y += trigger/ +obj-y += ultrasonic-distance/ diff --git a/drivers/iio/ultrasonic-distance/Kconfig b/drivers/iio/ultrasonic-distance/Kconfig new file mode 100644 index 0000000..46e848d --- /dev/null +++ b/drivers/iio/ultrasonic-distance/Kconfig @@ -0,0 +1,17 @@ +# +# Ultrasonic range sensors +# + +menu "Ultrasonic ranger devices" + +config HC_SR04 + tristate "HC-SR04 ultrasonic distance sensor on GPIO" + select IIO_SW_TRIGGER + depends on GPIOLIB + help + Say Y here if you want to support the HC-SR04 ultrasonic distance + sensor which is attached on two runtime-configurable GPIO pins. + + To compile this driver as a module, choose M here: the + module will be called hc-sr04. +endmenu diff --git a/drivers/iio/ultrasonic-distance/Makefile b/drivers/iio/ultrasonic-distance/Makefile new file mode 100644 index 0000000..1f01d50c --- /dev/null +++ b/drivers/iio/ultrasonic-distance/Makefile @@ -0,0 +1,6 @@ +# +# Makefile for IIO proximity sensors +# + +# When adding new entries keep the list in alphabetical order +obj-$(CONFIG_HC_SR04) += hc-sr04.o diff --git a/drivers/iio/ultrasonic-distance/hc-sr04.c b/drivers/iio/ultrasonic-distance/hc-sr04.c new file mode 100644 index 0000000..e7da37b --- /dev/null +++ b/drivers/iio/ultrasonic-distance/hc-sr04.c @@ -0,0 +1,466 @@ +/* + * hc-sr04.c - Support for HC-SR04 ultrasonic range sensor + * + * Copyright (C) 2016 Johannes Thoma <johannes@xxxxxxxxxxxxxxxxx> + * + * 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. + */ + +/* Precise measurements of time delta between sending a trigger signal + * to the HC-SR04 distance sensor and receiving the echo signal from + * the sensor back. This has to be precise in the usecs range. We + * use trigger interrupts to measure the signal, so no busy wait :) + * + * This supports an (in theory) unlimited number of HC-SR04 devices. + * It uses IIO software triggers to interface with userland. + * + * To configure a device do a + * + * mkdir /sys/kernel/config/iio/triggers/hc-sr04/sensor0 + * + * (you need to mount configfs to /sys/kernel/config first unless it isn't + * mounted already) + * + * Then configure the ECHO and TRIG pins (this also accepts symbolic names + * configured in the device tree) + * + * echo 23 > /config/iio/triggers/hc-sr04/sensor0/trig_pin + * echo 24 > /config/iio/triggers/hc-sr04/sensor0/echo_pin + * + * Then you can measure distance with: + * + * cat /sys/devices/trigger0/measure + * + * (trigger0 is the device name as reported by + * /config/iio/triggers/hc-sr04/sensor0/dev_name + * + * This reports the length of the ECHO signal in microseconds, which is + * related linearily to the distance measured. + * + * To convert to centimeters, multiply by 17150 and divide by 1000000 (air) + * + * DO NOT attach your HC-SR04's echo pin directly to the raspberry, since + * it runs with 5V while raspberry expects 3V on the GPIO inputs. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/timekeeping.h> +#include <linux/gpio/consumer.h> +#include <linux/mutex.h> +#include <linux/device.h> +#include <linux/sysfs.h> +#include <linux/interrupt.h> +#include <linux/kdev_t.h> +#include <linux/list.h> +#include <linux/slab.h> +#include <linux/gpio/driver.h> +#include <linux/delay.h> +#include <linux/sched.h> + +#include <linux/iio/iio.h> +#include <linux/iio/trigger.h> +#include <linux/iio/sw_trigger.h> + +#define DEFAULT_TIMEOUT 1000 + +enum hc_sr04_state { + DEVICE_IDLE, + DEVICE_TRIGGERED, + DEVICE_ECHO_RECEIVED +}; + +struct hc_sr04 { + /* the GPIOs of ECHO and TRIG */ + struct gpio_desc *trig_desc; + struct gpio_desc *echo_desc; + /* Used to measure length of ECHO signal */ + struct timeval time_triggered; + struct timeval time_echoed; + /* protects against starting multiple measurements */ + struct mutex measurement_mutex; + /* Current state of measurement */ + enum hc_sr04_state state; + /* Used by interrupt to wake measurement routine up */ + wait_queue_head_t wait_for_echo; + /* timeout in ms, fail when no echo received within that time */ + unsigned long timeout; + /* Our IIO interface */ + struct iio_sw_trigger swt; + /* Used to compute device settle time */ + struct timeval last_measurement; +}; + +static inline struct hc_sr04 *to_hc_sr04(struct config_item *item) +{ + struct iio_sw_trigger *trig = to_iio_sw_trigger(item); + + return container_of(trig, struct hc_sr04, swt); +} + +static irqreturn_t echo_received_irq(int irq, void *data) +{ + struct hc_sr04 *device = (struct hc_sr04 *)data; + int val; + struct timeval irq_tv; + + do_gettimeofday(&irq_tv); + + if (device->state != DEVICE_TRIGGERED) + return IRQ_HANDLED; + + val = gpiod_get_value(device->echo_desc); + if (val == 1) { + device->time_triggered = irq_tv; + } else { + device->time_echoed = irq_tv; + device->state = DEVICE_ECHO_RECEIVED; + wake_up_interruptible(&device->wait_for_echo); + } + + return IRQ_HANDLED; +} + +static int do_measurement(struct hc_sr04 *device, + long long *usecs_elapsed) +{ + long timeout; + int irq; + int ret; + struct timeval now; + long long time_since_last_measurement; + + *usecs_elapsed = -1; + + if (!device->echo_desc || !device->trig_desc) { + dev_dbg(&device->swt.trigger->dev, "Please configure GPIO pins first.\n"); + return -EINVAL; + } + if (!mutex_trylock(&device->measurement_mutex)) + return -EBUSY; + + do_gettimeofday(&now); + if (device->last_measurement.tv_sec || device->last_measurement.tv_usec) + time_since_last_measurement = + (now.tv_sec - device->last_measurement.tv_sec) * 1000000 + + (now.tv_usec - device->last_measurement.tv_usec); + else + time_since_last_measurement = 60000; + + /* wait 60 ms between measurements. + * now, a while true ; do cat measure ; done should work + */ + + if (time_since_last_measurement < 60000 && + time_since_last_measurement >= 0) + msleep(60 - (int)time_since_last_measurement / 1000); + + irq = gpiod_to_irq(device->echo_desc); + if (irq < 0) { + ret = -EIO; + goto out_mutex; + } + + ret = request_any_context_irq(irq, echo_received_irq, + IRQF_SHARED | IRQF_TRIGGER_FALLING | + IRQF_TRIGGER_RISING, + "hc_sr04", device); + + if (ret < 0) + goto out_mutex; + + gpiod_set_value(device->trig_desc, 1); + usleep_range(10, 20); + device->state = DEVICE_TRIGGERED; + gpiod_set_value(device->trig_desc, 0); + + ret = gpiochip_lock_as_irq(gpiod_to_chip(device->echo_desc), + desc_to_gpio(device->echo_desc)); + if (ret < 0) + goto out_irq; + + timeout = wait_event_interruptible_timeout( + device->wait_for_echo, + device->state == DEVICE_ECHO_RECEIVED, + device->timeout * HZ / 1000); + + device->state = DEVICE_IDLE; + + if (timeout == 0) { + ret = -ETIMEDOUT; + } else if (timeout < 0) { + ret = timeout; + } else { + *usecs_elapsed = + (device->time_echoed.tv_sec - device->time_triggered.tv_sec) * 1000000 + + (device->time_echoed.tv_usec - device->time_triggered.tv_usec); + ret = 0; + do_gettimeofday(&device->last_measurement); + } + gpiochip_unlock_as_irq(gpiod_to_chip(device->echo_desc), + desc_to_gpio(device->echo_desc)); +out_irq: + free_irq(irq, device); +out_mutex: + mutex_unlock(&device->measurement_mutex); + + return ret; +} + +static ssize_t sysfs_do_measurement(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct hc_sr04 *sensor = dev_get_drvdata(dev); + long long usecs_elapsed; + int status; + + status = do_measurement(sensor, &usecs_elapsed); + + if (status < 0) + return status; + + return sprintf(buf, "%lld\n", usecs_elapsed); +} + +DEVICE_ATTR(measure, 0444, sysfs_do_measurement, NULL); + +static struct attribute *sensor_attrs[] = { + &dev_attr_measure.attr, + NULL, +}; + +static const struct attribute_group sensor_group = { + .attrs = sensor_attrs +}; + +static const struct attribute_group *sensor_groups[] = { + &sensor_group, + NULL +}; + +static ssize_t configure_pin(struct gpio_desc **desc, struct config_item *item, + const char *buf, size_t len, struct device *dev) +{ + int err; + int echo; + + if (*desc) + gpiod_put(*desc); + + *desc = gpiod_get(dev, buf, GPIOD_ASIS); + if (IS_ERR(*desc)) { + err = PTR_ERR(*desc); + *desc = NULL; + + if (err == -ENOENT) { /* fallback: use GPIO numbers */ + err = kstrtoint(buf, 10, &echo); + if (err < 0) + return -ENOENT; + *desc = gpio_to_desc(echo); + if (*desc) + return len; + return -ENOENT; + } + + return err; + } + return len; +} + +static ssize_t hc_sr04_echo_pin_store(struct config_item *item, + const char *buf, size_t len) +{ + struct hc_sr04 *sensor = to_hc_sr04(item); + ssize_t ret; + int err; + + ret = configure_pin(&sensor->echo_desc, item, buf, len, + &sensor->swt.trigger->dev); + + if (ret >= 0 && sensor->echo_desc) { + err = gpiod_direction_input(sensor->echo_desc); + if (err < 0) + return err; + } + return ret; +} + +static ssize_t hc_sr04_echo_pin_show(struct config_item *item, + char *buf) +{ + struct hc_sr04 *sensor = to_hc_sr04(item); + + if (sensor->echo_desc) + return sprintf(buf, "%d\n", desc_to_gpio(sensor->echo_desc)); + return 0; +} + +static ssize_t hc_sr04_trig_pin_store(struct config_item *item, + const char *buf, size_t len) +{ + struct hc_sr04 *sensor = to_hc_sr04(item); + ssize_t ret; + int err; + + ret = configure_pin(&sensor->trig_desc, item, buf, len, + &sensor->swt.trigger->dev); + + if (ret >= 0 && sensor->trig_desc) { + err = gpiod_direction_output(sensor->trig_desc, 0); + if (err >= 0) + gpiod_set_value(sensor->trig_desc, 0); + else + return err; + } + return ret; +} + +static ssize_t hc_sr04_trig_pin_show(struct config_item *item, + char *buf) +{ + struct hc_sr04 *sensor = to_hc_sr04(item); + + if (sensor->trig_desc) + return sprintf(buf, "%d\n", desc_to_gpio(sensor->trig_desc)); + return 0; +} + +static ssize_t hc_sr04_timeout_store(struct config_item *item, + const char *buf, size_t len) +{ + struct hc_sr04 *sensor = to_hc_sr04(item); + unsigned long t; + int ret; + + ret = kstrtol(buf, 10, &t); + if (ret < 0) + return ret; + + sensor->timeout = t; + return len; +} + +static ssize_t hc_sr04_timeout_show(struct config_item *item, + char *buf) +{ + struct hc_sr04 *sensor = to_hc_sr04(item); + + return sprintf(buf, "%ld\n", sensor->timeout); +} + +static ssize_t hc_sr04_dev_name_show(struct config_item *item, + char *buf) +{ + struct hc_sr04 *sensor = to_hc_sr04(item); + + return sprintf(buf, "%s", dev_name(&sensor->swt.trigger->dev)); +} + +CONFIGFS_ATTR(hc_sr04_, echo_pin); +CONFIGFS_ATTR(hc_sr04_, trig_pin); +CONFIGFS_ATTR(hc_sr04_, timeout); +CONFIGFS_ATTR_RO(hc_sr04_, dev_name); + +static struct configfs_attribute *hc_sr04_config_attrs[] = { + &hc_sr04_attr_echo_pin, + &hc_sr04_attr_trig_pin, + &hc_sr04_attr_timeout, + &hc_sr04_attr_dev_name, + NULL +}; + +static struct config_item_type iio_hc_sr04_type = { + .ct_owner = THIS_MODULE, + .ct_attrs = hc_sr04_config_attrs +}; + +static int iio_trig_hc_sr04_set_state(struct iio_trigger *trig, bool state) +{ + return 0; +} + +static const struct iio_trigger_ops iio_hc_sr04_trigger_ops = { + .owner = THIS_MODULE, + .set_trigger_state = iio_trig_hc_sr04_set_state, +}; + +static struct iio_sw_trigger *iio_trig_hc_sr04_probe(const char *name) +{ + struct hc_sr04 *sensor; + int ret; + + sensor = kzalloc(sizeof(*sensor), GFP_KERNEL); + if (!sensor) + return ERR_PTR(-ENOMEM); + + mutex_init(&sensor->measurement_mutex); + init_waitqueue_head(&sensor->wait_for_echo); + sensor->timeout = DEFAULT_TIMEOUT; + + sensor->swt.trigger = iio_trigger_alloc("%s", name); + if (!sensor->swt.trigger) { + ret = -ENOMEM; + goto err_free_sensor; + } + iio_trigger_set_drvdata(sensor->swt.trigger, sensor); + sensor->swt.trigger->ops = &iio_hc_sr04_trigger_ops; + sensor->swt.trigger->dev.groups = sensor_groups; + + ret = iio_trigger_register(sensor->swt.trigger); + if (ret) + goto err_free_trigger; + + iio_swt_group_init_type_name(&sensor->swt, name, &iio_hc_sr04_type); + return &sensor->swt; + +err_free_trigger: + iio_trigger_free(sensor->swt.trigger); +err_free_sensor: + kfree(sensor); + + return ERR_PTR(ret); +} + +static int iio_trig_hc_sr04_remove(struct iio_sw_trigger *swt) +{ + struct hc_sr04 *rip_sensor; + + rip_sensor = iio_trigger_get_drvdata(swt->trigger); + + iio_trigger_unregister(swt->trigger); + + /* Wait for measurement to be finished. */ + mutex_lock(&rip_sensor->measurement_mutex); + + iio_trigger_free(swt->trigger); + kfree(rip_sensor); + + return 0; +} + +static const struct iio_sw_trigger_ops iio_trig_hc_sr04_ops = { + .probe = iio_trig_hc_sr04_probe, + .remove = iio_trig_hc_sr04_remove, +}; + +static struct iio_sw_trigger_type iio_trig_hc_sr04 = { + .name = "hc-sr04", + .owner = THIS_MODULE, + .ops = &iio_trig_hc_sr04_ops, +}; + +module_iio_sw_trigger_driver(iio_trig_hc_sr04); + +MODULE_AUTHOR("Johannes Thoma"); +MODULE_DESCRIPTION("Distance measurement for the HC-SR04 ultrasonic distance sensor"); +MODULE_LICENSE("GPL"); + -- 2.8.0-rc4 -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
