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From: Liam Beguin <liambeguin@gmail.com>
To: liambeguin@gmail.com, peda@axentia.se, jic23@kernel.org,
	lars@metafoo.de, pmeerw@pmeerw.net
Cc: linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org,
	devicetree@vger.kernel.org, robh+dt@kernel.org
Subject: [PATCH v3 03/10] iio: inkern: make a best effort on offset calculation
Date: Wed, 30 Jun 2021 21:00:27 -0400	[thread overview]
Message-ID: <20210701010034.303088-4-liambeguin@gmail.com> (raw)
In-Reply-To: <20210701010034.303088-1-liambeguin@gmail.com>

From: Liam Beguin <lvb@xiphos.com>

iio_convert_raw_to_processed_unlocked() assumes the offset is an
integer. Make a best effort to get a valid offset value for fractional
cases without breaking implicit truncations.

Fixes: 48e44ce0f881 ("iio:inkern: Add function to read the processed value")
Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/inkern.c | 36 +++++++++++++++++++++++++++++++-----
 1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index b69027690ed5..e1712c1099c5 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -578,13 +578,39 @@ EXPORT_SYMBOL_GPL(iio_read_channel_average_raw);
 static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,
 	int raw, int *processed, unsigned int scale)
 {
-	int scale_type, scale_val, scale_val2, offset;
+	int scale_type, scale_val, scale_val2;
+	int offset_type, offset_val, offset_val2;
 	s64 raw64 = raw;
-	int ret;
+	int tmp;
 
-	ret = iio_channel_read(chan, &offset, NULL, IIO_CHAN_INFO_OFFSET);
-	if (ret >= 0)
-		raw64 += offset;
+	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:
+			break;
+		case IIO_VAL_INT_PLUS_MICRO:
+			fallthrough;
+		case IIO_VAL_INT_PLUS_NANO:
+			/*
+			 * Both IIO_VAL_INT_PLUS_MICRO and IIO_VAL_INT_PLUS_NANO
+			 * implicitely truncate the offset to it's integer form.
+			 */
+			break;
+		case IIO_VAL_FRACTIONAL:
+			tmp = offset_val / offset_val2;
+			offset_val = tmp;
+			break;
+		case IIO_VAL_FRACTIONAL_LOG2:
+			tmp = offset_val / (1 << offset_val2);
+			offset_val = tmp;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		raw64 += offset_val;
+	}
 
 	scale_type = iio_channel_read(chan, &scale_val, &scale_val2,
 					IIO_CHAN_INFO_SCALE);
-- 
2.30.1.489.g328c10930387


  parent reply	other threads:[~2021-07-01  1:02 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-01  1:00 [PATCH v3 00/10] iio: afe: add temperature rescaling support Liam Beguin
2021-07-01  1:00 ` [PATCH v3 01/10] iio: inkern: apply consumer scale on IIO_VAL_INT cases Liam Beguin
2021-07-01  1:00 ` [PATCH v3 02/10] iio: inkern: apply consumer scale when no channel scale is available Liam Beguin
2021-07-01  1:00 ` Liam Beguin [this message]
2021-07-04 16:26   ` [PATCH v3 03/10] iio: inkern: make a best effort on offset calculation Jonathan Cameron
2021-07-04 18:03     ` Liam Beguin
2021-07-01  1:00 ` [PATCH v3 04/10] iio: afe: rescale: reduce risk of integer overflow Liam Beguin
2021-07-04 16:36   ` Jonathan Cameron
2021-07-05  4:23     ` Liam Beguin
2021-07-05  8:29       ` Jonathan Cameron
2021-07-01  1:00 ` [PATCH v3 05/10] iio: afe: rescale: add INT_PLUS_{MICRO,NANO} support Liam Beguin
2021-07-04 16:37   ` Jonathan Cameron
2021-07-01  1:00 ` [PATCH v3 06/10] iio: afe: rescale: add offset support Liam Beguin
2021-07-04 16:53   ` Jonathan Cameron
2021-07-05  4:27     ` Liam Beguin
2021-07-01  1:00 ` [PATCH v3 07/10] iio: afe: rescale: add RTD temperature sensor support Liam Beguin
2021-07-01  1:00 ` [PATCH v3 08/10] iio: afe: rescale: add temperature transducers Liam Beguin
2021-07-01  1:00 ` [PATCH v3 09/10] dt-bindings: iio: afe: add bindings for temperature-sense-rtd Liam Beguin
2021-07-04 17:02   ` Jonathan Cameron
2021-07-05  4:31     ` Liam Beguin
2021-07-01  1:00 ` [PATCH v3 10/10] dt-bindings: iio: afe: add bindings for temperature transducers Liam Beguin

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