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333 lines
8.6 KiB
333 lines
8.6 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* PING: ultrasonic sensor for distance measuring by using only one GPIOs |
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* |
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* Copyright (c) 2019 Andreas Klinger <[email protected]> |
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* |
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* For details about the devices see: |
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* http://parallax.com/sites/default/files/downloads/28041-LaserPING-2m-Rangefinder-Guide.pdf |
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* http://parallax.com/sites/default/files/downloads/28015-PING-Documentation-v1.6.pdf |
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* |
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* the measurement cycle as timing diagram looks like: |
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* |
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* GPIO ___ ________________________ |
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* ping: __/ \____________/ \________________ |
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* ^ ^ ^ ^ |
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* |<->| interrupt interrupt |
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* udelay(5) (ts_rising) (ts_falling) |
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* |<---------------------->| |
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* . pulse time measured . |
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* . --> one round trip of ultra sonic waves |
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* ultra . . |
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* sonic _ _ _. . |
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* burst: _________/ \_/ \_/ \_________________________________________ |
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* . |
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* ultra . |
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* sonic _ _ _. |
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* echo: __________________________________/ \_/ \_/ \________________ |
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*/ |
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#include <linux/err.h> |
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#include <linux/gpio/consumer.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/of.h> |
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#include <linux/of_device.h> |
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#include <linux/platform_device.h> |
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#include <linux/property.h> |
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#include <linux/sched.h> |
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#include <linux/interrupt.h> |
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#include <linux/delay.h> |
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#include <linux/iio/iio.h> |
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#include <linux/iio/sysfs.h> |
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struct ping_cfg { |
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unsigned long trigger_pulse_us; /* length of trigger pulse */ |
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int laserping_error; /* support error code in */ |
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/* pulse width of laser */ |
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/* ping sensors */ |
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s64 timeout_ns; /* timeout in ns */ |
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}; |
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struct ping_data { |
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struct device *dev; |
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struct gpio_desc *gpiod_ping; |
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struct mutex lock; |
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int irqnr; |
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ktime_t ts_rising; |
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ktime_t ts_falling; |
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struct completion rising; |
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struct completion falling; |
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const struct ping_cfg *cfg; |
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}; |
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static const struct ping_cfg pa_ping_cfg = { |
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.trigger_pulse_us = 5, |
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.laserping_error = 0, |
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.timeout_ns = 18500000, /* 3 meters */ |
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}; |
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static const struct ping_cfg pa_laser_ping_cfg = { |
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.trigger_pulse_us = 5, |
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.laserping_error = 1, |
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.timeout_ns = 15500000, /* 2 meters plus error codes */ |
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}; |
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static irqreturn_t ping_handle_irq(int irq, void *dev_id) |
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{ |
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struct iio_dev *indio_dev = dev_id; |
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struct ping_data *data = iio_priv(indio_dev); |
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ktime_t now = ktime_get(); |
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if (gpiod_get_value(data->gpiod_ping)) { |
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data->ts_rising = now; |
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complete(&data->rising); |
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} else { |
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data->ts_falling = now; |
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complete(&data->falling); |
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} |
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return IRQ_HANDLED; |
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} |
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static int ping_read(struct iio_dev *indio_dev) |
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{ |
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struct ping_data *data = iio_priv(indio_dev); |
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int ret; |
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ktime_t ktime_dt; |
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s64 dt_ns; |
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u32 time_ns, distance_mm; |
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struct platform_device *pdev = to_platform_device(data->dev); |
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/* |
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* just one read-echo-cycle can take place at a time |
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* ==> lock against concurrent reading calls |
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*/ |
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mutex_lock(&data->lock); |
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reinit_completion(&data->rising); |
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reinit_completion(&data->falling); |
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gpiod_set_value(data->gpiod_ping, 1); |
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udelay(data->cfg->trigger_pulse_us); |
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gpiod_set_value(data->gpiod_ping, 0); |
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ret = gpiod_direction_input(data->gpiod_ping); |
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if (ret < 0) { |
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mutex_unlock(&data->lock); |
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return ret; |
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} |
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data->irqnr = gpiod_to_irq(data->gpiod_ping); |
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if (data->irqnr < 0) { |
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dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr); |
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mutex_unlock(&data->lock); |
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return data->irqnr; |
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} |
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ret = request_irq(data->irqnr, ping_handle_irq, |
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IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, |
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pdev->name, indio_dev); |
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if (ret < 0) { |
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dev_err(data->dev, "request_irq: %d\n", ret); |
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mutex_unlock(&data->lock); |
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return ret; |
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} |
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/* it should not take more than 20 ms until echo is rising */ |
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ret = wait_for_completion_killable_timeout(&data->rising, HZ/50); |
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if (ret < 0) |
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goto err_reset_direction; |
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else if (ret == 0) { |
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ret = -ETIMEDOUT; |
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goto err_reset_direction; |
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} |
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/* it cannot take more than 50 ms until echo is falling */ |
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ret = wait_for_completion_killable_timeout(&data->falling, HZ/20); |
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if (ret < 0) |
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goto err_reset_direction; |
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else if (ret == 0) { |
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ret = -ETIMEDOUT; |
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goto err_reset_direction; |
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} |
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ktime_dt = ktime_sub(data->ts_falling, data->ts_rising); |
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free_irq(data->irqnr, indio_dev); |
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ret = gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW); |
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if (ret < 0) { |
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mutex_unlock(&data->lock); |
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return ret; |
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} |
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mutex_unlock(&data->lock); |
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dt_ns = ktime_to_ns(ktime_dt); |
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if (dt_ns > data->cfg->timeout_ns) { |
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dev_dbg(data->dev, "distance out of range: dt=%lldns\n", |
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dt_ns); |
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return -EIO; |
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} |
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time_ns = dt_ns; |
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/* |
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* read error code of laser ping sensor and give users chance to |
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* figure out error by using dynamic debuggging |
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*/ |
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if (data->cfg->laserping_error) { |
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if ((time_ns > 12500000) && (time_ns <= 13500000)) { |
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dev_dbg(data->dev, "target too close or to far\n"); |
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return -EIO; |
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} |
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if ((time_ns > 13500000) && (time_ns <= 14500000)) { |
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dev_dbg(data->dev, "internal sensor error\n"); |
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return -EIO; |
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} |
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if ((time_ns > 14500000) && (time_ns <= 15500000)) { |
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dev_dbg(data->dev, "internal sensor timeout\n"); |
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return -EIO; |
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} |
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} |
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/* |
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* the speed as function of the temperature is approximately: |
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* |
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* speed = 331,5 + 0,6 * Temp |
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* with Temp in °C |
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* and speed in m/s |
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* |
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* use 343,5 m/s as ultrasonic speed at 20 °C here in absence of the |
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* temperature |
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* |
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* therefore: |
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* time 343,5 time * 232 |
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* distance = ------ * ------- = ------------ |
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* 10^6 2 1350800 |
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* with time in ns |
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* and distance in mm (one way) |
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* |
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* because we limit to 3 meters the multiplication with 232 just |
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* fits into 32 bit |
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*/ |
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distance_mm = time_ns * 232 / 1350800; |
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return distance_mm; |
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err_reset_direction: |
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free_irq(data->irqnr, indio_dev); |
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mutex_unlock(&data->lock); |
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if (gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW)) |
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dev_dbg(data->dev, "error in gpiod_direction_output\n"); |
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return ret; |
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} |
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static int ping_read_raw(struct iio_dev *indio_dev, |
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struct iio_chan_spec const *channel, int *val, |
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int *val2, long info) |
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{ |
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int ret; |
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if (channel->type != IIO_DISTANCE) |
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return -EINVAL; |
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switch (info) { |
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case IIO_CHAN_INFO_RAW: |
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ret = ping_read(indio_dev); |
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if (ret < 0) |
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return ret; |
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*val = ret; |
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return IIO_VAL_INT; |
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case IIO_CHAN_INFO_SCALE: |
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/* |
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* maximum resolution in datasheet is 1 mm |
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* 1 LSB is 1 mm |
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*/ |
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*val = 0; |
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*val2 = 1000; |
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return IIO_VAL_INT_PLUS_MICRO; |
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default: |
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return -EINVAL; |
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} |
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} |
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static const struct iio_info ping_iio_info = { |
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.read_raw = ping_read_raw, |
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}; |
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static const struct iio_chan_spec ping_chan_spec[] = { |
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{ |
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.type = IIO_DISTANCE, |
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.info_mask_separate = |
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BIT(IIO_CHAN_INFO_RAW) | |
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BIT(IIO_CHAN_INFO_SCALE), |
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}, |
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}; |
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static const struct of_device_id of_ping_match[] = { |
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{ .compatible = "parallax,ping", .data = &pa_ping_cfg}, |
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{ .compatible = "parallax,laserping", .data = &pa_laser_ping_cfg}, |
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{}, |
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}; |
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MODULE_DEVICE_TABLE(of, of_ping_match); |
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static int ping_probe(struct platform_device *pdev) |
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{ |
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struct device *dev = &pdev->dev; |
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struct ping_data *data; |
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struct iio_dev *indio_dev; |
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indio_dev = devm_iio_device_alloc(dev, sizeof(struct ping_data)); |
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if (!indio_dev) { |
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dev_err(dev, "failed to allocate IIO device\n"); |
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return -ENOMEM; |
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} |
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data = iio_priv(indio_dev); |
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data->dev = dev; |
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data->cfg = of_device_get_match_data(dev); |
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mutex_init(&data->lock); |
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init_completion(&data->rising); |
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init_completion(&data->falling); |
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data->gpiod_ping = devm_gpiod_get(dev, "ping", GPIOD_OUT_LOW); |
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if (IS_ERR(data->gpiod_ping)) { |
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dev_err(dev, "failed to get ping-gpios: err=%ld\n", |
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PTR_ERR(data->gpiod_ping)); |
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return PTR_ERR(data->gpiod_ping); |
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} |
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if (gpiod_cansleep(data->gpiod_ping)) { |
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dev_err(data->dev, "cansleep-GPIOs not supported\n"); |
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return -ENODEV; |
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} |
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platform_set_drvdata(pdev, indio_dev); |
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indio_dev->name = "ping"; |
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indio_dev->info = &ping_iio_info; |
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indio_dev->modes = INDIO_DIRECT_MODE; |
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indio_dev->channels = ping_chan_spec; |
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indio_dev->num_channels = ARRAY_SIZE(ping_chan_spec); |
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return devm_iio_device_register(dev, indio_dev); |
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} |
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static struct platform_driver ping_driver = { |
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.probe = ping_probe, |
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.driver = { |
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.name = "ping-gpio", |
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.of_match_table = of_ping_match, |
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}, |
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}; |
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module_platform_driver(ping_driver); |
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MODULE_AUTHOR("Andreas Klinger <[email protected]>"); |
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MODULE_DESCRIPTION("PING sensors for distance measuring using one GPIOs"); |
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS("platform:ping");
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