linux-kernel - Re: [PATCH] iio: humidity: hdc3020: add threshold events support

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Date: Sat, 3 Feb 2024 10:30:09 +0100
From: Javier Carrasco <javier.carrasco.cruz@...il.com>
To: Dimitri Fedrau <dima.fedrau@...il.com>
Cc: Li peiyu <579lpy@...il.com>, Jonathan Cameron <jic23@...nel.org>,
 Lars-Peter Clausen <lars@...afoo.de>, linux-iio@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: humidity: hdc3020: add threshold events support

Hi Dimitri,

On 03.02.24 10:05, Dimitri Fedrau wrote:
> Add threshold events support for temperature and relative humidity. To
> enable them the higher and lower threshold registers must be programmed
> and the higher threshold must be greater then or equal to the lower
> threshold. Otherwise the event is disabled. Invalid hysteresis values
> are ignored by the device. There is no further configuration possible.
> 
> Tested by setting thresholds/hysteresis and turning the heater on/off.
> Used iio_event_monitor in tools/iio to catch events while constantly
> displaying temperature and humidity values.
> Threshold and hysteresis values are cached in the driver, used i2c-tools
> to read the threshold and hysteresis values from the device and make
> sure cached values are consistent to values written to the device.
> 
> Based on Fix:
> a69eeaad093d "iio: humidity: hdc3020: fix temperature offset" in branch
> fixes-togreg
> 
> Signed-off-by: Dimitri Fedrau <dima.fedrau@...il.com>
> ---
>  drivers/iio/humidity/hdc3020.c | 339 +++++++++++++++++++++++++++++++++
>  1 file changed, 339 insertions(+)
> 

..

> +static int hdc3020_write_thresh(struct iio_dev *indio_dev,
> +				const struct iio_chan_spec *chan,
> +				enum iio_event_type type,
> +				enum iio_event_direction dir,
> +				enum iio_event_info info,
> +				int val, int val2)
> +{
> +	struct hdc3020_data *data = iio_priv(indio_dev);
> +	u16 *thresh;
> +	u8 buf[5];
> +	int ret;
> +
> +	/* Supported temperature range is from –40 to 125 degree celsius */
Should that not be val < -40?
> +	if (val < -45 || val > 125)
> +		return -EINVAL;
> +
> +	/* Select threshold and associated register */
> +	if (info == IIO_EV_INFO_VALUE) {
> +		if (dir == IIO_EV_DIR_RISING) {
> +			thresh = &data->t_rh_thresh_high;
> +			memcpy(buf, HDC3020_S_T_RH_THRESH_HIGH, 2);
> +		} else {
> +			thresh = &data->t_rh_thresh_low;
> +			memcpy(buf, HDC3020_S_T_RH_THRESH_LOW, 2);
> +		}
> +	} else {
> +		if (dir == IIO_EV_DIR_RISING) {
> +			thresh = &data->t_rh_thresh_high_clr;
> +			memcpy(buf, HDC3020_S_T_RH_THRESH_HIGH_CLR, 2);
> +		} else {
> +			thresh = &data->t_rh_thresh_low_clr;
> +			memcpy(buf, HDC3020_S_T_RH_THRESH_LOW_CLR, 2);
> +		}
> +	}
> +
> +	guard(mutex)(&data->lock);
> +	switch (chan->type) {
> +	case IIO_TEMP:
> +		/*
> +		 * Store truncated temperature threshold into 9 LSBs while
> +		 * keeping the old humidity threshold in the 7 MSBs.
> +		 
> +		val = (((val + 45) * 65535 / 175) >> HDC3020_THRESH_TEMP_SHIFT);
> +		val &= HDC3020_THRESH_TEMP_MASK;
> +		val |= (*thresh & HDC3020_THRESH_HUM_MASK);
> +		break;
> +	case IIO_HUMIDITYRELATIVE:
> +		/*
> +		 * Store truncated humidity threshold into 7 MSBs while
> +		 * keeping the old temperature threshold in the 9 LSBs.
> +		 */
> +		val = ((val * 65535 / 100) & HDC3020_THRESH_HUM_MASK);
> +		val |= (*thresh & HDC3020_THRESH_TEMP_MASK);
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	put_unaligned_be16(val, &buf[2]);
> +	buf[4] = crc8(hdc3020_crc8_table, buf + 2, 2, CRC8_INIT_VALUE);
> +	ret = hdc3020_write_bytes(data, buf, 5);
> +	if (ret)
> +		return ret;
> +
> +	/* Update threshold */
> +	*thresh = val;
> +
> +	return 0;
> +}
> +
> 

Best regards,
Javier Carrasco