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([2600:8803:e7e4:1d00:70a1:e065:6248:ef8b]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7524986ca64sm4301216a34.14.2025.09.16.12.23.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 16 Sep 2025 12:23:05 -0700 (PDT) Message-ID: Date: Tue, 16 Sep 2025 14:23:04 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/4] iio: add processed write API To: Romain Gantois , Liam Girdwood , Mark Brown , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Jonathan Cameron , =?UTF-8?Q?Nuno_S=C3=A1?= , Andy Shevchenko Cc: Thomas Petazzoni , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-iio@vger.kernel.org References: <20250916-ltm8054-driver-v1-0-fd4e781d33b9@bootlin.com> <20250916-ltm8054-driver-v1-2-fd4e781d33b9@bootlin.com> Content-Language: en-US From: David Lechner In-Reply-To: <20250916-ltm8054-driver-v1-2-fd4e781d33b9@bootlin.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/16/25 5:24 AM, Romain Gantois wrote: > Add a function to allow IIO consumers to write a processed value to a > channel. > > Signed-off-by: Romain Gantois > --- > drivers/iio/inkern.c | 99 ++++++++++++++++++++++++++++++++++++++++++++ > include/linux/iio/consumer.h | 17 ++++++++ > 2 files changed, 116 insertions(+) > > diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c > index c174ebb7d5e6d183674b7ffb15c4ce0f65fa3aed..6486fdb7c66a4c84312541f0f42cc24469972a9c 100644 > --- a/drivers/iio/inkern.c > +++ b/drivers/iio/inkern.c > @@ -598,6 +598,85 @@ int iio_read_channel_average_raw(struct iio_channel *chan, int *val) > } > EXPORT_SYMBOL_GPL(iio_read_channel_average_raw); > > +static int iio_convert_processed_to_raw_unlocked(struct iio_channel *chan, > + int processed, int *raw, > + unsigned int scale) > +{ > + int scale_type, scale_val, scale_val2; > + int offset_type, offset_val, offset_val2; > + s64 tmp_num, tmp_den; > + > + scale_type = iio_channel_read(chan, &scale_val, &scale_val2, > + IIO_CHAN_INFO_SCALE); > + if (scale_type >= 0) { > + switch (scale_type) { > + case IIO_VAL_INT: > + tmp_num = processed; > + tmp_den = scale_val; > + break; > + case IIO_VAL_INT_PLUS_MICRO: > + tmp_num = (s64)processed * 1000000LL; > + > + if (scale_val2 < 0) { > + tmp_den = (s64)scale_val * 1000000LL - (s64)scale_val2; > + tmp_den *= -1; > + } else { > + tmp_den = (s64)scale_val * 1000000LL + (s64)scale_val2; > + } > + > + break; > + case IIO_VAL_INT_PLUS_NANO: > + tmp_num = (s64)processed * 1000000000LL; > + > + if (scale_val2 < 0) { > + tmp_den = (s64)scale_val * 1000000000LL - (s64)scale_val2; > + tmp_den *= -1; > + } else { > + tmp_den = (s64)scale_val * 1000000000LL + (s64)scale_val2; > + } > + > + break; > + case IIO_VAL_FRACTIONAL: > + tmp_num = (s64)processed * (s64)scale_val2; > + tmp_den = scale_val; > + break; > + case IIO_VAL_FRACTIONAL_LOG2: > + tmp_num = (s64)processed << scale_val2; > + tmp_den = scale_val; > + break; > + default: > + return -EINVAL; > + } > + > + tmp_den *= scale; > + > + *raw = div64_s64(tmp_num, tmp_den); > + } It can be quite tricky to get all of these combinations right. I would prefer if added some unit tests like we did in [1]. [1]: https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/commit/?h=testing&id=c732e60ee10ed0611a59513cbf9c8d35fbe7cf65 > + > + offset_type = iio_channel_read(chan, &offset_val, &offset_val2, > + IIO_CHAN_INFO_OFFSET); > + if (offset_type >= 0) { > + switch (offset_type) { > + case IIO_VAL_INT: > + case IIO_VAL_INT_PLUS_MICRO: > + case IIO_VAL_INT_PLUS_NANO: > + break; > + case IIO_VAL_FRACTIONAL: > + offset_val /= offset_val2; > + break; > + case IIO_VAL_FRACTIONAL_LOG2: > + offset_val >>= offset_val2; > + break; > + default: > + return -EINVAL; > + } > + > + *raw -= offset_val; > + } > + > + return 0; > +}