Re: [PATCH 2/4] iio: chemical: add driver for dsm501/ppd42ns particle sensors

From: Matt Ranostay
Date: Mon Feb 06 2017 - 01:52:52 EST


> On Feb 5, 2017, at 08:24, Tomasz Duszynski <tduszyns@xxxxxxxxx> wrote:
>
> Thanks for review!
>
>> On Sun, Feb 05, 2017 at 04:19:47PM +0100, Peter Meerwald-Stadler wrote:
>>
>>> This patch adds support for dsm501 and ppd42ns particle sensors.
>>
>> quick comments below
>> G
>>> 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.
>>>

This a SI unit?

Also this maybe could be better off in drivers/iio/light... as much I like to have other people in drivers/iio/chemical ð
>>> Signed-off-by: Tomasz Duszynski <tduszyns@xxxxxxxxx>
>>> ---
>>> 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 <tduszyns@xxxxxxxxx>
>>> + *
>>> + * 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
> Ack.
>>
>>> +
>>> +#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?
> No. I've put that sidenote so that others looking at figures in
> datahseets won't scratch their heads why units here are pcs/m3 and
> pcs/0.01cf there. Anyway I am happy to drop that part.
>>
>>> + */
>>> +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?
> According to CodingStyle yes. {} could be dropped if there was single
> statement under if (val) { ...
>>
>>> +
>>> + 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
> Ack.
>>
>>> + 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
> Are you refering to function naming here? *_number_concentration was named
> after returned physical quantity.
>>
>>> + },
>>> + {
>>> + .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 <tduszyns@xxxxxxxxx>");
>>> +MODULE_DESCRIPTION("Samyoung DSM501 particle sensor driver");
>>> +MODULE_LICENSE("GPL v2");
>>>
>>
>> --
>>
>> Peter Meerwald-Stadler
>> +43-664-2444418 (mobile)
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