diff options
Diffstat (limited to 'drivers/iio/proximity/srf04.c')
| -rw-r--r-- | drivers/iio/proximity/srf04.c | 408 |
1 files changed, 408 insertions, 0 deletions
diff --git a/drivers/iio/proximity/srf04.c b/drivers/iio/proximity/srf04.c new file mode 100644 index 000000000..420c37c72 --- /dev/null +++ b/drivers/iio/proximity/srf04.c @@ -0,0 +1,408 @@ +// 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) + pm_runtime_get_sync(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_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"); |