linux-kernel - Re: [PATCH v3 3/6] iio: pressure: add SCALE and RAW values for channels

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Message-ID: <20240314144838.49b62a72@jic23-huawei>
Date: Thu, 14 Mar 2024 14:48:38 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Vasileios Amoiridis <vassilisamir@...il.com>
Cc: lars@...afoo.de, andriy.shevchenko@...ux.intel.com,
 ang.iglesiasg@...il.com, mazziesaccount@...il.com, ak@...klinger.de,
 petre.rodan@...dimension.ro, linus.walleij@...aro.org,
 phil@...pberrypi.com, 579lpy@...il.com, linux-iio@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/6] iio: pressure: add SCALE and RAW values for
 channels

On Wed, 13 Mar 2024 18:40:04 +0100
Vasileios Amoiridis <vassilisamir@...il.com> wrote:

> Add extra IIO_CHAN_INFO_SCALE and IIO_CHAN_INFO_RAW in order to be
> able to calculate the processed value with standard userspace IIO
> tools. Can be used for triggered buffers as well.
> 
> Signed-off-by: Vasileios Amoiridis <vassilisamir@...il.com>
> ---
>  drivers/iio/pressure/bmp280-core.c | 58 ++++++++++++++++++++++++++++++
>  1 file changed, 58 insertions(+)
> 
> diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
> index dfd845acfa22..6d7734f867bc 100644
> --- a/drivers/iio/pressure/bmp280-core.c
> +++ b/drivers/iio/pressure/bmp280-core.c
> @@ -138,16 +138,22 @@ static const struct iio_chan_spec bmp280_channels[] = {
>  	{
>  		.type = IIO_PRESSURE,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |

Next to each (or at least the first) existing entry for PROCESSED add a
comment that says it is maintained for ABI backwards compatibility reasons.
I really don't want people copying the result of this patch into new drivers
- we've ended up here because of a less than ideal decision in the past, that
history doesn't apply to other drivers.

> +				      BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
>  				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
>  	},
>  	{
>  		.type = IIO_TEMP,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +				      BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
>  				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
>  	},
>  	{
>  		.type = IIO_HUMIDITYRELATIVE,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +				      BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
>  				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
>  	},
>  };
> @@ -156,6 +162,8 @@ static const struct iio_chan_spec bmp380_channels[] = {
>  	{
>  		.type = IIO_PRESSURE,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +				      BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
>  				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
>  		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) |
>  					   BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY),
> @@ -163,6 +171,8 @@ static const struct iio_chan_spec bmp380_channels[] = {
>  	{
>  		.type = IIO_TEMP,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +				      BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
>  				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
>  		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) |
>  					   BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY),
> @@ -170,6 +180,8 @@ static const struct iio_chan_spec bmp380_channels[] = {
>  	{
>  		.type = IIO_HUMIDITYRELATIVE,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +				      BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
>  				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
>  		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) |
>  					   BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY),
> @@ -485,6 +497,52 @@ static int bmp280_read_raw(struct iio_dev *indio_dev,
>  			break;
>  		}
>  		break;
> +	case IIO_CHAN_INFO_RAW:
> +		switch (chan->type) {
> +		case IIO_HUMIDITYRELATIVE:
> +			*val = data->chip_info->read_humid(data);
> +			ret = IIO_VAL_INT;
> +			break;
> +		case IIO_PRESSURE:
> +			*val = data->chip_info->read_press(data);
> +			ret = IIO_VAL_INT;
> +			break;
> +		case IIO_TEMP:
> +			*val = data->chip_info->read_temp(data);
> +			ret = IIO_VAL_INT;
> +			break;
> +		default:
> +			ret = -EINVAL;
> +			break;
> +		}
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_HUMIDITYRELATIVE:
> +			*val = data->chip_info->humid_coeffs[0];
> +			*val2 = data->chip_info->humid_coeffs[1];
> +			ret = IIO_VAL_FRACTIONAL;
> +			break;
> +		case IIO_PRESSURE:
> +			*val = data->chip_info->press_coeffs[0];
> +			*val2 = data->chip_info->press_coeffs[1];
> +			ret = IIO_VAL_FRACTIONAL;
> +			break;
> +		case IIO_TEMP:
> +			*val = data->chip_info->temp_coeffs[0];
> +			*val2 = data->chip_info->temp_coeffs[1];
> +
> +			if (!strcmp(indio_dev->name, "bmp580"))
> +				ret = IIO_VAL_FRACTIONAL_LOG2;
> +			else
> +				ret = IIO_VAL_FRACTIONAL;
> +
> +			break;
> +		default:
> +			ret = -EINVAL;
> +			break;
> +		}
> +		break;
>  	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
>  		switch (chan->type) {
>  		case IIO_HUMIDITYRELATIVE: