> This patch adds support for dsm501 and ppd42ns particle sensors.
quick comments below
> Both sensors work on the same principle. Heater (resistor) heats up air
> in sensor chamber which induces upward flow. Particles convect up through
> a light beam provided by internal infra-red LED. Light scattered by
> particles is picked by photodiode and internal electronics outputs PWM
> signal.
>
> Measuring low time occupancy of the signal during 30s measurement period
> particles number in cubic meter can be computed.
>
> Signed-off-by: Tomasz Duszynski <tdusz...@gmail.com>
> ---
> drivers/iio/chemical/Kconfig | 10 ++
> drivers/iio/chemical/Makefile | 1 +
> drivers/iio/chemical/dsm501.c | 231
> ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 242 insertions(+)
> create mode 100644 drivers/iio/chemical/dsm501.c
>
> diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
> index cea7f9857a1f..986d612aa77f 100644
> --- a/drivers/iio/chemical/Kconfig
> +++ b/drivers/iio/chemical/Kconfig
> @@ -21,6 +21,16 @@ config ATLAS_PH_SENSOR
> To compile this driver as module, choose M here: the
> module will be called atlas-ph-sensor.
>
> +config DSM501
> + tristate "Samyoung DSM501 particle sensor"
> + depends on GPIOLIB
> + help
> + Say yes here to build support for the Samyoung DSM501
> + particle sensor.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called dsm501.
> +
> config IAQCORE
> tristate "AMS iAQ-Core VOC sensors"
> depends on I2C
> diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
> index b02202b41289..76f50ff8ba7d 100644
> --- a/drivers/iio/chemical/Makefile
> +++ b/drivers/iio/chemical/Makefile
> @@ -4,5 +4,6 @@
>
> # When adding new entries keep the list in alphabetical order
> obj-$(CONFIG_ATLAS_PH_SENSOR) += atlas-ph-sensor.o
> +obj-$(CONFIG_DSM501) += dsm501.o
> obj-$(CONFIG_IAQCORE) += ams-iaq-core.o
> obj-$(CONFIG_VZ89X) += vz89x.o
> diff --git a/drivers/iio/chemical/dsm501.c b/drivers/iio/chemical/dsm501.c
> new file mode 100644
> index 000000000000..013f6b3bfd48
> --- /dev/null
> +++ b/drivers/iio/chemical/dsm501.c
> @@ -0,0 +1,231 @@
> +/*
> + * Samyoung DSM501 particle sensor driver
> + *
> + * Copyright (C) 2017 Tomasz Duszynski <tdusz...@gmail.com>
> + *
> + * Datasheets:
> + * http://www.samyoungsnc.com/products/3-1%20Specification%20DSM501.pdf
> + * http://wiki.timelab.org/images/f/f9/PPD42NS.pdf
> + *
> + * 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.
> + *
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/timekeeping.h>
> +
> +#define DSM501_DRV_NAME "dsm501"
> +#define DSM501_IRQ_NAME "dsm501_irq"
replace tab by space
> +
> +#define DSM501_DEFAULT_MEASUREMENT_TIME 30 /* seconds */
> +
> +struct dsm501_data {
> + ktime_t ts;
> + ktime_t low_time;
> + ktime_t meas_time;
> +
> + int irq;
> + struct gpio_desc *gpio;
> +
> + struct mutex lock;
> +
> + int (*number_concentration)(struct dsm501_data *data);
> +};
> +
> +/*
> + * Series of data points in Fig. 8-3 (Low Ratio vs Particle)
> + * can be approximated by following polynomials:
> + *
> + * p(r) = 0 (undefined) for r < 4
> + * p(r) = 2353564.2r - 4373814.7 for 4 <= r < 20
> + * p(r) = 4788112.4r - 53581390 for r >= 20
> + *
> + * Note: Result is in pcs/m3. To convert to pcs/0.01cf multiply
> + * by 0.0002831685.
is cf needed?
> + */
> +static int dsm501_number_concentartion(struct dsm501_data *data)
> +{
> + s64 retval = 0, r = div64_s64(ktime_to_ns(data->low_time) * 100,
> + ktime_to_ns(data->meas_time));
> +
> + if (r >= 4 && r < 20)
> + retval = 23535642 * r - 43738147;
> + else if (r >= 20)
> + retval = 47881124 * r - 535813900;
> +
> + return div_s64(retval, 10);
> +}
> +
> +/*
> + * Series of data points in Fig. 2 (Lo Pulse Occupancy Time vs Concentration)
> + * can be approximated by following polynomial:
> + *
> + * p(r) = 3844.2r^3 - 16201.3r^2 + 1848746.1r + 52497.2
> + *
> + * Note: Result is in pcs/m3. To convert to pcs/0.01cf multiply
> + * by 0.0002831685.
> + */
> +static int ppd42ns_number_concentration(struct dsm501_data *data)
> +{
> + s64 retval, r3, r2, r = div64_s64(ktime_to_ns(data->low_time) * 100,
> + ktime_to_ns(data->meas_time));
> +
> + r2 = r * r;
> + r3 = r2 * r;
> +
> + retval = 38442 * r3;
> + retval -= 162013 * r2;
> + retval += 18487461 * r;
> + retval += 524972;
> +
> + return div_s64(retval, 10);
> +}
> +
> +static irqreturn_t dsm501_irq(int irq, void *dev_id)
> +{
> + struct dsm501_data *data = iio_priv(dev_id);
> + int val = gpiod_get_value(data->gpio);
> + ktime_t dt, ts = ktime_get();
> +
> + if (ktime_to_ns(data->ts) == 0) {
> + data->ts = ts;
> + data->low_time = ktime_set(0, 0);
> + }
> +
> + if (val) {
> + dt = ktime_sub(ts, data->ts);
> + data->low_time = ktime_add(data->low_time, dt);
> + } else {
> + data->ts = ts;
> + }
{} needed?
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int dsm501_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan, int *val,
> + int *val2, long mask)
> +{
> + struct dsm501_data *data = iio_priv(indio_dev);
> + struct device *dev = indio_dev->dev.parent;
> + unsigned long irqflags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;
> + int ret;
> +
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_PROCESSED:
> + mutex_lock(&data->lock);
> + data->ts = ktime_set(0, 0);
> +
> + ret = devm_request_irq(dev, data->irq, dsm501_irq, irqflags,
> + DSM501_IRQ_NAME, indio_dev);
why devm_()? if the irq is explicitly freed below?
requesting the irq for every measurement seems weird even if it only
happens every 30s
> + if (ret) {
> + dev_err(dev, "Failed to request interrupt %d\n",
> data->irq);
> + mutex_unlock(&data->lock);
> + return ret;
> + }
> +
> + msleep_interruptible(ktime_to_ms(data->meas_time));
> + devm_free_irq(dev, data->irq, indio_dev);
> +
> + *val = data->number_concentration(data);
> + mutex_unlock(&data->lock);
> +
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static const struct iio_info dsm501_info = {
> + .driver_module = THIS_MODULE,
> + .read_raw = dsm501_read_raw,
> +};
> +
> +static const struct iio_chan_spec dsm501_channels[] = {
> + {
> + .type = IIO_NUMBERCONCENTRATION,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> + },
> +};
> +
> +static int dsm501_probe(struct platform_device *pdev)
> +{
> + struct dsm501_data *data;
> + struct iio_dev *indio_dev;
> + struct device *dev = &pdev->dev;
> +
> + indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*data));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + data = iio_priv(indio_dev);
> + platform_set_drvdata(pdev, indio_dev);
> +
> + data->gpio = devm_gpiod_get_index(dev, NULL, 0, GPIOD_IN);
> + if (IS_ERR(data->gpio)) {
> + dev_err(dev, "Failed to get GPIO\n");
> + return PTR_ERR(data->gpio);
> + }
> +
> + data->irq = gpiod_to_irq(data->gpio);
> + if (data->irq < 0) {
> + dev_err(dev, "GPIO has no interrupt\n");
> + return data->irq;
> + }
> +
> + data->meas_time = ktime_set(DSM501_DEFAULT_MEASUREMENT_TIME, 0);
> + data->number_concentration = of_device_get_match_data(dev);
> + mutex_init(&data->lock);
> +
> + indio_dev->name = DSM501_DRV_NAME;
> + indio_dev->dev.parent = dev;
> + indio_dev->info = &dsm501_info;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = dsm501_channels;
> + indio_dev->num_channels = ARRAY_SIZE(dsm501_channels);
> +
> + return devm_iio_device_register(&pdev->dev, indio_dev);
> +}
> +
> +static const struct of_device_id dsm501_id[] = {
> + {
> + .compatible = "samyoung,dsm501",
> + .data = dsm501_number_concentartion,
type: concentration
> + },
> + {
> + .compatible = "shinyei,ppd42ns",
> + .data = ppd42ns_number_concentration,
> + },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, dsm501_id);
> +
> +static struct platform_driver dsm501_driver = {
> + .driver = {
> + .name = DSM501_DRV_NAME,
> + .of_match_table = of_match_ptr(dsm501_id)
> + },
> + .probe = dsm501_probe
> +};
> +module_platform_driver(dsm501_driver);
> +
> +MODULE_AUTHOR("Tomasz Duszynski <tdusz...@gmail.com>");
> +MODULE_DESCRIPTION("Samyoung DSM501 particle sensor driver");
> +MODULE_LICENSE("GPL v2");
>
--
Peter Meerwald-Stadler
+43-664-2444418 (mobile)
