linux-kernel - Re: [PATCH 2/4] iio: pressure: Add scale value for channels

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Date: Sat, 9 Mar 2024 18:28:42 +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, phil@...pberrypi.com, 579lpy@...il.com,
 linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] iio: pressure: Add scale value for channels

On Sun,  3 Mar 2024 17:52:58 +0100
Vasileios Amoiridis <vassilisamir@...il.com> wrote:

> Add extra IIO_CHAN_INFO_SCALE in order to be able to have the scales
> for the values in userspace. Can be used for triggered buffers.
> 
> Signed-off-by: Vasileios Amoiridis <vassilisamir@...il.com>

So providing scale and processed is a mess. With hindsight this should have
always provided raw + scale, but too late :(

This retrofitting buffered code onto a drive that does processed channels
is one of the few reasons I'll let through channels that do both processed and raw.
So add raw as well. Hopefully raw * scale always equals processed.

The reason is that for a channel doing processed only - assumption is
normally that the buffer is processed as well. We can't remove processed
as that would be ABI breakage, but we can add raw.

Jonathan

> ---
>  drivers/iio/pressure/bmp280-core.c | 70 ++++++++++++++++++++++++++++++
>  1 file changed, 70 insertions(+)
> 
> diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
> index 29a8b7195076..acdf6138d317 100644
> --- a/drivers/iio/pressure/bmp280-core.c
> +++ b/drivers/iio/pressure/bmp280-core.c
> @@ -138,16 +138,19 @@ static const struct iio_chan_spec bmp280_channels[] = {
>  	{
>  		.type = IIO_PRESSURE,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +				      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_SCALE) |
>  				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
>  	},
>  	{
>  		.type = IIO_HUMIDITYRELATIVE,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
>  				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
>  	},
>  };
> @@ -156,6 +159,7 @@ static const struct iio_chan_spec bmp380_channels[] = {
>  	{
>  		.type = IIO_PRESSURE,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +				      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 +167,7 @@ static const struct iio_chan_spec bmp380_channels[] = {
>  	{
>  		.type = IIO_TEMP,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +				      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 +175,7 @@ static const struct iio_chan_spec bmp380_channels[] = {
>  	{
>  		.type = IIO_HUMIDITYRELATIVE,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +				      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),
> @@ -487,6 +493,70 @@ static int bmp280_read_raw(struct iio_dev *indio_dev,
>  			break;
>  		}
>  		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_HUMIDITYRELATIVE:
> +			if (!strcmp(indio_dev->name, "bme280")) {
> +				*val = 1000;
> +				*val2 = 1024;
> +				ret = IIO_VAL_FRACTIONAL;
> +			} else {
> +				ret = -EINVAL;
> +			}
> +			break;
> +		case IIO_PRESSURE:
> +			if ((!strcmp(indio_dev->name, "bmp085")) ||
> +			    (!strcmp(indio_dev->name, "bmp180")) ||
> +			    (!strcmp(indio_dev->name, "bmp181"))) {
> +				*val = 1;
> +				*val2 = 1000;
> +				ret = IIO_VAL_FRACTIONAL;
> +			} else if ((!strcmp(indio_dev->name, "bmp280")) ||
> +				   (!strcmp(indio_dev->name, "bme280"))) {
> +				*val = 1;
> +				*val2 = 256000;
> +				ret = IIO_VAL_FRACTIONAL;
> +			} else if (!strcmp(indio_dev->name, "bmp380")) {
> +				*val = 1;
> +				*val2 = 100000;
> +				ret = IIO_VAL_FRACTIONAL;
> +			} else if (!strcmp(indio_dev->name, "bmp580")) {
> +				*val = 1;
> +				*val2 = 64000;
> +				ret = IIO_VAL_FRACTIONAL;
> +			} else {
> +				ret = -EINVAL;
> +			}
> +			break;
> +		case IIO_TEMP:
> +			if ((!strcmp(indio_dev->name, "bmp085")) ||
> +			    (!strcmp(indio_dev->name, "bmp180")) ||
> +			    (!strcmp(indio_dev->name, "bmp181"))) {
> +				*val = 100;
> +				*val2 = 1;
> +				ret = IIO_VAL_FRACTIONAL;
> +			} else if ((!strcmp(indio_dev->name, "bmp280")) ||
> +				   (!strcmp(indio_dev->name, "bme280"))) {
> +				*val = 10;
> +				*val2 = 1;
> +				ret = IIO_VAL_FRACTIONAL;
> +			} else if (!strcmp(indio_dev->name, "bmp380")) {
> +				*val = 10;
> +				*val2 = 1;
> +				ret = IIO_VAL_FRACTIONAL;
> +			} else if (!strcmp(indio_dev->name, "bmp580")) {
> +				*val = 1000;
> +				*val2 = 16;
> +				ret = IIO_VAL_FRACTIONAL_LOG2;
> +			} else {
> +				ret = -EINVAL;
> +			}
> +			break;
> +		default:
> +			ret = -EINVAL;
> +			break;
> +		}
> +		break;
>  	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
>  		switch (chan->type) {
>  		case IIO_HUMIDITYRELATIVE: