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* [PATCH v10 00/14] iio: afe: add temperature rescaling support
@ 2021-12-19 22:39 Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 01/14] iio: inkern: apply consumer scale on IIO_VAL_INT cases Liam Beguin
                   ` (14 more replies)
  0 siblings, 15 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

Hi Jonathan, Peter,

I left out IIO_VAL_INT overflows for now, so that I can focus on getting
the rest of these changes pulled in, but I don't mind adding a patch for
that later on.

This series focuses on adding temperature rescaling support to the IIO
Analog Front End (AFE) driver.

The first few patches address minor bugs in IIO inkernel functions, and
prepare the AFE driver for the additional features.

The main changes to the AFE driver include an initial Kunit test suite,
support for IIO_VAL_INT_PLUS_{NANO,MICRO} scales, and support for RTDs
and temperature transducer sensors.

Thanks for your time,
Liam

Changes since v9:
- make use of linux/units.h
- reorder commits, fix fract_log2 before merging fract
- keep fractional representation when not overflowing

Changes since v8:
- reword comment
- fix erroneous 64-bit division
- optimize and use 32-bit divisions when values are know to not overflow
- keep IIO_VAL_FRACTIONAL scale when possible, if not default to fixed
  point
- add test cases
- use nano precision in test cases
- simplify offset calculation in rtd_props()

Changes since v7:
- drop gcd() logic in rescale_process_scale()
- use div_s64() instead of do_div() for signed 64-bit divisions
- combine IIO_VAL_FRACTIONAL and IIO_VAL_FRACTIONAL_LOG2 scale cases
- switch to INT_PLUS_NANO when accuracy is lost with FRACTIONAL scales
- rework test logic to allow for small relative error
- rename test variables to align error output messages

Changes since v6:
- rework IIO_VAL_INT_PLUS_{NANO,MICRO} based on Peter's suggestion
- combine IIO_VAL_INT_PLUS_{NANO,MICRO} cases
- add test cases for negative IIO_VAL_INT_PLUS_{NANO,MICRO} corner cases
- force use of positive integers with gcd()
- reduce risk of integer overflow in IIO_VAL_FRACTIONAL_LOG2
- fix duplicate symbol build error
- apply Reviewed-by

Changes since v5:
- add include/linux/iio/afe/rescale.h
- expose functions use to process scale and offset
- add basic iio-rescale kunit test cases
- fix integer overflow case
- improve precision for IIO_VAL_FRACTIONAL_LOG2

Changes since v4:
- only use gcd() when necessary in overflow mitigation
- fix INT_PLUS_{MICRO,NANO} support
- apply Reviewed-by
- fix temperature-transducer bindings

Changes since v3:
- drop unnecessary fallthrough statements
- drop redundant local variables in some calculations
- fix s64 divisions on 32bit platforms by using do_div
- add comment describing iio-rescaler offset calculation
- drop unnecessary MAINTAINERS entry

Changes since v2:
- don't break implicit offset truncations
- make a best effort to get a valid value for fractional types
- drop return value change in iio_convert_raw_to_processed_unlocked()
- don't rely on processed value for offset calculation
- add INT_PLUS_{MICRO,NANO} support in iio-rescale
- revert generic implementation in favor of temperature-sense-rtd and
  temperature-transducer
- add separate section to MAINTAINERS file

Changes since v1:
- rebase on latest iio `testing` branch
- also apply consumer scale on integer channel scale types
- don't break implicit truncation in processed channel offset
  calculation
- drop temperature AFE flavors in favor of a simpler generic
  implementation

Liam Beguin (14):
  iio: inkern: apply consumer scale on IIO_VAL_INT cases
  iio: inkern: apply consumer scale when no channel scale is available
  iio: inkern: make a best effort on offset calculation
  iio: afe: rescale: expose scale processing function
  iio: afe: rescale: add INT_PLUS_{MICRO,NANO} support
  iio: afe: rescale: add offset support
  iio: afe: rescale: use s64 for temporary scale calculations
  iio: afe: rescale: fix accuracy for small fractional scales
  iio: afe: rescale: reduce risk of integer overflow
  iio: test: add basic tests for the iio-rescale driver
  iio: afe: rescale: add RTD temperature sensor support
  iio: afe: rescale: add temperature transducers
  dt-bindings: iio: afe: add bindings for temperature-sense-rtd
  dt-bindings: iio: afe: add bindings for temperature transducers

 .../iio/afe/temperature-sense-rtd.yaml        | 101 +++
 .../iio/afe/temperature-transducer.yaml       | 114 +++
 drivers/iio/afe/iio-rescale.c                 | 283 ++++++-
 drivers/iio/inkern.c                          |  40 +-
 drivers/iio/test/Kconfig                      |  10 +
 drivers/iio/test/Makefile                     |   1 +
 drivers/iio/test/iio-test-rescale.c           | 705 ++++++++++++++++++
 include/linux/iio/afe/rescale.h               |  34 +
 8 files changed, 1244 insertions(+), 44 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml
 create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-transducer.yaml
 create mode 100644 drivers/iio/test/iio-test-rescale.c
 create mode 100644 include/linux/iio/afe/rescale.h

Range-diff against v9:
 -:  ------------ >  1:  ae3cc93baee6 iio: inkern: apply consumer scale on IIO_VAL_INT cases
 -:  ------------ >  2:  06f66e7f7403 iio: inkern: apply consumer scale when no channel scale is available
 -:  ------------ >  3:  2dbf6b3bbaeb iio: inkern: make a best effort on offset calculation
 -:  ------------ >  4:  b083cf307268 iio: afe: rescale: expose scale processing function
 1:  a0bde29ecc8c !  5:  f46b59690e46 iio: afe: rescale: add INT_PLUS_{MICRO,NANO} support
    @@ Commit message
         Signed-off-by: Liam Beguin <lvb@xiphos.com>
     
      ## drivers/iio/afe/iio-rescale.c ##
    -@@ drivers/iio/afe/iio-rescale.c: int rescale_process_scale(struct rescale *rescale, int scale_type,
    +@@
    + #include <linux/of_device.h>
    + #include <linux/platform_device.h>
    + #include <linux/property.h>
    ++#include <linux/units.h>
    + 
    + int rescale_process_scale(struct rescale *rescale, int scale_type,
      			  int *val, int *val2)
      {
      	unsigned long long tmp;
    @@ drivers/iio/afe/iio-rescale.c: int rescale_process_scale(struct rescale *rescale
     +		return scale_type;
     +	case IIO_VAL_INT_PLUS_NANO:
     +	case IIO_VAL_INT_PLUS_MICRO:
    -+		if (scale_type == IIO_VAL_INT_PLUS_NANO)
    -+			mult = 1000000000LL;
    -+		else
    -+			mult = 1000000LL;
    ++		mult = scale_type == IIO_VAL_INT_PLUS_NANO ? NANO : MICRO;
    ++
     +		/*
     +		 * For IIO_VAL_INT_PLUS_{MICRO,NANO} scale types if either *val
     +		 * OR *val2 is negative the schan scale is negative, i.e.
 2:  c3d0e6248033 =  6:  80701b87cdf4 iio: afe: rescale: add offset support
 3:  2a81fa735103 =  7:  a3d8fb812678 iio: afe: rescale: use s64 for temporary scale calculations
 4:  8315548d0fce <  -:  ------------ iio: afe: rescale: reduce risk of integer overflow
 5:  223ed0569cd2 !  8:  b83947d96676 iio: afe: rescale: fix accuracy for small fractional scales
    @@ drivers/iio/afe/iio-rescale.c: int rescale_process_scale(struct rescale *rescale
     +		if (!rem)
     +			return scale_type;
     +
    -+		if (scale_type == IIO_VAL_FRACTIONAL)
    -+			tmp = *val2;
    -+		else
    -+			tmp = 1 << *val2;
    ++		tmp = 1 << *val2;
     +
     +		rem2 = *val % (int)tmp;
     +		*val = *val / (int)tmp;
    @@ drivers/iio/afe/iio-rescale.c: int rescale_process_scale(struct rescale *rescale
     +		return IIO_VAL_INT_PLUS_NANO;
      	case IIO_VAL_INT_PLUS_NANO:
      	case IIO_VAL_INT_PLUS_MICRO:
    - 		if (scale_type == IIO_VAL_INT_PLUS_NANO)
    + 		mult = scale_type == IIO_VAL_INT_PLUS_NANO ? NANO : MICRO;
 -:  ------------ >  9:  c42c8121bcdf iio: afe: rescale: reduce risk of integer overflow
 6:  90044efdf8be = 10:  6c87d491a275 iio: test: add basic tests for the iio-rescale driver
 7:  c4ed463e5fb0 = 11:  3f3d1939b17c iio: afe: rescale: add RTD temperature sensor support
 8:  ff2f0dc248a7 = 12:  0c83d15f3b92 iio: afe: rescale: add temperature transducers
 9:  84bc1f7d1ab5 = 13:  55af6c9391f8 dt-bindings: iio: afe: add bindings for temperature-sense-rtd
10:  1b76cfb37e23 = 14:  8f9cd46c702e dt-bindings: iio: afe: add bindings for temperature transducers

base-commit: 2b6bff0b122785f09cfbdc34b1aa9edceea6e4c1
-- 
2.34.0


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v10 01/14] iio: inkern: apply consumer scale on IIO_VAL_INT cases
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 02/14] iio: inkern: apply consumer scale when no channel scale is available Liam Beguin
                   ` (13 subsequent siblings)
  14 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

When a consumer calls iio_read_channel_processed() and the channel has
an integer scale, the scale channel scale is applied and the processed
value is returned as expected.

On the other hand, if the consumer calls iio_convert_raw_to_processed()
the scaling factor requested by the consumer is not applied.

This for example causes the consumer to process mV when expecting uV.
Make sure to always apply the scaling factor requested by the consumer.

Fixes: 48e44ce0f881 ("iio:inkern: Add function to read the processed value")
Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/inkern.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 0222885b334c..021e1397ffc5 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -616,7 +616,7 @@ static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,
 
 	switch (scale_type) {
 	case IIO_VAL_INT:
-		*processed = raw64 * scale_val;
+		*processed = raw64 * scale_val * scale;
 		break;
 	case IIO_VAL_INT_PLUS_MICRO:
 		if (scale_val2 < 0)
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 02/14] iio: inkern: apply consumer scale when no channel scale is available
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 01/14] iio: inkern: apply consumer scale on IIO_VAL_INT cases Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 03/14] iio: inkern: make a best effort on offset calculation Liam Beguin
                   ` (12 subsequent siblings)
  14 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

When a consumer calls iio_read_channel_processed() and no channel scale
is available, it's assumed that the scale is one and the raw value is
returned as expected.

On the other hand, if the consumer calls iio_convert_raw_to_processed()
the scaling factor requested by the consumer is not applied.

This for example causes the consumer to process mV when expecting uV.
Make sure to always apply the scaling factor requested by the consumer.

Fixes: adc8ec5ff183 ("iio: inkern: pass through raw values if no scaling")
Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/inkern.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 021e1397ffc5..dbe13fad3cbb 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -607,10 +607,10 @@ static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,
 					IIO_CHAN_INFO_SCALE);
 	if (scale_type < 0) {
 		/*
-		 * Just pass raw values as processed if no scaling is
-		 * available.
+		 * If no channel scaling is available apply consumer scale to
+		 * raw value and return.
 		 */
-		*processed = raw;
+		*processed = raw * scale;
 		return 0;
 	}
 
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 03/14] iio: inkern: make a best effort on offset calculation
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 01/14] iio: inkern: apply consumer scale on IIO_VAL_INT cases Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 02/14] iio: inkern: apply consumer scale when no channel scale is available Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-21  5:42   ` Andy Shevchenko
  2021-12-19 22:39 ` [PATCH v10 04/14] iio: afe: rescale: expose scale processing function Liam Beguin
                   ` (11 subsequent siblings)
  14 siblings, 1 reply; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

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 | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index dbe13fad3cbb..aff6d2d3447c 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -595,13 +595,35 @@ 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;
 
-	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:
+		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:
+			offset_val /= offset_val2;
+			break;
+		case IIO_VAL_FRACTIONAL_LOG2:
+			offset_val /= (1 << offset_val2);
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		raw64 += offset_val;
+	}
 
 	scale_type = iio_channel_read(chan, &scale_val, &scale_val2,
 					IIO_CHAN_INFO_SCALE);
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 04/14] iio: afe: rescale: expose scale processing function
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (2 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 03/14] iio: inkern: make a best effort on offset calculation Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
       [not found]   ` <CAHp75VdfPf6FMvkGqhhQg5e5XE1cgE-K8seobe5n0yGarnPGtQ@mail.gmail.com>
  2021-12-19 22:39 ` [PATCH v10 05/14] iio: afe: rescale: add INT_PLUS_{MICRO,NANO} support Liam Beguin
                   ` (10 subsequent siblings)
  14 siblings, 1 reply; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

In preparation for the addition of kunit tests, expose the logic
responsible for combining channel scales.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/afe/iio-rescale.c   | 65 ++++++++++++++-------------------
 include/linux/iio/afe/rescale.h | 30 +++++++++++++++
 2 files changed, 58 insertions(+), 37 deletions(-)
 create mode 100644 include/linux/iio/afe/rescale.h

diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index 774eb3044edd..d0669fd8eac5 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -11,35 +11,46 @@
 #include <linux/gcd.h>
 #include <linux/iio/consumer.h>
 #include <linux/iio/iio.h>
+#include <linux/iio/afe/rescale.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
 
-struct rescale;
-
-struct rescale_cfg {
-	enum iio_chan_type type;
-	int (*props)(struct device *dev, struct rescale *rescale);
-};
+int rescale_process_scale(struct rescale *rescale, int scale_type,
+			  int *val, int *val2)
+{
+	unsigned long long tmp;
 
-struct rescale {
-	const struct rescale_cfg *cfg;
-	struct iio_channel *source;
-	struct iio_chan_spec chan;
-	struct iio_chan_spec_ext_info *ext_info;
-	bool chan_processed;
-	s32 numerator;
-	s32 denominator;
-};
+	switch (scale_type) {
+	case IIO_VAL_FRACTIONAL:
+		*val *= rescale->numerator;
+		*val2 *= rescale->denominator;
+		return scale_type;
+	case IIO_VAL_INT:
+		*val *= rescale->numerator;
+		if (rescale->denominator == 1)
+			return scale_type;
+		*val2 = rescale->denominator;
+		return IIO_VAL_FRACTIONAL;
+	case IIO_VAL_FRACTIONAL_LOG2:
+		tmp = *val * 1000000000LL;
+		do_div(tmp, rescale->denominator);
+		tmp *= rescale->numerator;
+		do_div(tmp, 1000000000LL);
+		*val = tmp;
+		return scale_type;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
 
 static int rescale_read_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *chan,
 			    int *val, int *val2, long mask)
 {
 	struct rescale *rescale = iio_priv(indio_dev);
-	unsigned long long tmp;
 	int ret;
 
 	switch (mask) {
@@ -65,27 +76,7 @@ static int rescale_read_raw(struct iio_dev *indio_dev,
 		} else {
 			ret = iio_read_channel_scale(rescale->source, val, val2);
 		}
-		switch (ret) {
-		case IIO_VAL_FRACTIONAL:
-			*val *= rescale->numerator;
-			*val2 *= rescale->denominator;
-			return ret;
-		case IIO_VAL_INT:
-			*val *= rescale->numerator;
-			if (rescale->denominator == 1)
-				return ret;
-			*val2 = rescale->denominator;
-			return IIO_VAL_FRACTIONAL;
-		case IIO_VAL_FRACTIONAL_LOG2:
-			tmp = *val * 1000000000LL;
-			do_div(tmp, rescale->denominator);
-			tmp *= rescale->numerator;
-			do_div(tmp, 1000000000LL);
-			*val = tmp;
-			return ret;
-		default:
-			return -EOPNOTSUPP;
-		}
+		return rescale_process_scale(rescale, ret, val, val2);
 	default:
 		return -EINVAL;
 	}
diff --git a/include/linux/iio/afe/rescale.h b/include/linux/iio/afe/rescale.h
new file mode 100644
index 000000000000..14d4ee1227c6
--- /dev/null
+++ b/include/linux/iio/afe/rescale.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 Liam Beguin <liambeguin@gmail.com>
+ */
+
+#ifndef __IIO_RESCALE_H__
+#define __IIO_RESCALE_H__
+
+#include <linux/iio/iio.h>
+
+struct rescale;
+
+struct rescale_cfg {
+	enum iio_chan_type type;
+	int (*props)(struct device *dev, struct rescale *rescale);
+};
+
+struct rescale {
+	const struct rescale_cfg *cfg;
+	struct iio_channel *source;
+	struct iio_chan_spec chan;
+	struct iio_chan_spec_ext_info *ext_info;
+	bool chan_processed;
+	s32 numerator;
+	s32 denominator;
+};
+
+int rescale_process_scale(struct rescale *rescale, int scale_type,
+			  int *val, int *val2);
+#endif /* __IIO_RESCALE_H__ */
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 05/14] iio: afe: rescale: add INT_PLUS_{MICRO,NANO} support
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (3 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 04/14] iio: afe: rescale: expose scale processing function Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 06/14] iio: afe: rescale: add offset support Liam Beguin
                   ` (9 subsequent siblings)
  14 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

Some ADCs use IIO_VAL_INT_PLUS_{NANO,MICRO} scale types.
Add support for these to allow using the iio-rescaler with them.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/afe/iio-rescale.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index d0669fd8eac5..190a83e08008 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -17,11 +17,15 @@
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
+#include <linux/units.h>
 
 int rescale_process_scale(struct rescale *rescale, int scale_type,
 			  int *val, int *val2)
 {
 	unsigned long long tmp;
+	s32 rem;
+	u32 mult;
+	u32 neg;
 
 	switch (scale_type) {
 	case IIO_VAL_FRACTIONAL:
@@ -40,6 +44,37 @@ int rescale_process_scale(struct rescale *rescale, int scale_type,
 		tmp *= rescale->numerator;
 		do_div(tmp, 1000000000LL);
 		*val = tmp;
+		return scale_type;
+	case IIO_VAL_INT_PLUS_NANO:
+	case IIO_VAL_INT_PLUS_MICRO:
+		mult = scale_type == IIO_VAL_INT_PLUS_NANO ? NANO : MICRO;
+
+		/*
+		 * For IIO_VAL_INT_PLUS_{MICRO,NANO} scale types if either *val
+		 * OR *val2 is negative the schan scale is negative, i.e.
+		 * *val = 1 and *val2 = -0.5 yields -1.5 not -0.5.
+		 */
+		neg = *val < 0 || *val2 < 0;
+
+		tmp = (s64)abs(*val) * abs(rescale->numerator);
+		*val = div_s64_rem(tmp, abs(rescale->denominator), &rem);
+
+		tmp = (s64)rem * mult + (s64)abs(*val2) * abs(rescale->numerator);
+		tmp = div_s64(tmp, abs(rescale->denominator));
+
+		*val += div_s64_rem(tmp, mult, val2);
+
+		/*
+		 * If only one of the rescaler elements or the schan scale is
+		 * negative, the combined scale is negative.
+		 */
+		if (neg ^ ((rescale->numerator < 0) ^ (rescale->denominator < 0))) {
+			if (*val)
+				*val = -*val;
+			else
+				*val2 = -*val2;
+		}
+
 		return scale_type;
 	default:
 		return -EOPNOTSUPP;
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 06/14] iio: afe: rescale: add offset support
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (4 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 05/14] iio: afe: rescale: add INT_PLUS_{MICRO,NANO} support Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 07/14] iio: afe: rescale: use s64 for temporary scale calculations Liam Beguin
                   ` (8 subsequent siblings)
  14 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

This is a preparatory change required for the addition of temperature
sensing front ends.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/afe/iio-rescale.c   | 80 +++++++++++++++++++++++++++++++++
 include/linux/iio/afe/rescale.h |  4 ++
 2 files changed, 84 insertions(+)

diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index 190a83e08008..e88b63747a46 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -81,11 +81,46 @@ int rescale_process_scale(struct rescale *rescale, int scale_type,
 	}
 }
 
+int rescale_process_offset(struct rescale *rescale, int scale_type,
+			   int scale, int scale2, int schan_off,
+			   int *val, int *val2)
+{
+	s64 tmp, tmp2;
+
+	switch (scale_type) {
+	case IIO_VAL_FRACTIONAL:
+		tmp = (s64)rescale->offset * scale2;
+		*val = div_s64(tmp, scale) + schan_off;
+		return IIO_VAL_INT;
+	case IIO_VAL_INT:
+		*val = div_s64(rescale->offset, scale) + schan_off;
+		return IIO_VAL_INT;
+	case IIO_VAL_FRACTIONAL_LOG2:
+		tmp = (s64)rescale->offset * (1 << scale2);
+		*val = div_s64(tmp, scale) + schan_off;
+		return IIO_VAL_INT;
+	case IIO_VAL_INT_PLUS_NANO:
+		tmp = (s64)rescale->offset * 1000000000;
+		tmp2 = ((s64)scale * 1000000000L) + scale2;
+		*val = div64_s64(tmp, tmp2) + schan_off;
+		return IIO_VAL_INT;
+	case IIO_VAL_INT_PLUS_MICRO:
+		tmp = (s64)rescale->offset * 1000000L;
+		tmp2 = ((s64)scale * 1000000L) + scale2;
+		*val = div64_s64(tmp, tmp2) + schan_off;
+		return IIO_VAL_INT;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
 static int rescale_read_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *chan,
 			    int *val, int *val2, long mask)
 {
 	struct rescale *rescale = iio_priv(indio_dev);
+	int scale, scale2;
+	int schan_off = 0;
 	int ret;
 
 	switch (mask) {
@@ -112,6 +147,47 @@ static int rescale_read_raw(struct iio_dev *indio_dev,
 			ret = iio_read_channel_scale(rescale->source, val, val2);
 		}
 		return rescale_process_scale(rescale, ret, val, val2);
+	case IIO_CHAN_INFO_OFFSET:
+		/*
+		 * Processed channels are scaled 1-to-1 and source offset is
+		 * already taken into account.
+		 *
+		 * In other cases, real world measurement are expressed as:
+		 *
+		 *	schan_scale * (raw + schan_offset)
+		 *
+		 * Given that the rescaler parameters are applied recursively:
+		 *
+		 *	rescaler_scale * (schan_scale * (raw + schan_offset) +
+		 *		rescaler_offset)
+		 *
+		 * Or,
+		 *
+		 *	(rescaler_scale * schan_scale) * (raw +
+		 *		(schan_offset +	rescaler_offset / schan_scale)
+		 *
+		 * Thus, reusing the original expression the parameters exposed
+		 * to userspace are:
+		 *
+		 *	scale = schan_scale * rescaler_scale
+		 *	offset = schan_offset + rescaler_offset / schan_scale
+		 */
+		if (rescale->chan_processed) {
+			*val = rescale->offset;
+			return IIO_VAL_INT;
+		}
+
+		if (iio_channel_has_info(rescale->source->channel,
+					 IIO_CHAN_INFO_OFFSET)) {
+			ret = iio_read_channel_offset(rescale->source,
+						      &schan_off, NULL);
+			if (ret != IIO_VAL_INT)
+				return ret < 0 ? ret : -EOPNOTSUPP;
+		}
+
+		ret = iio_read_channel_scale(rescale->source, &scale, &scale2);
+		return rescale_process_offset(rescale, ret, scale, scale2,
+					      schan_off, val, val2);
 	default:
 		return -EINVAL;
 	}
@@ -188,6 +264,9 @@ static int rescale_configure_channel(struct device *dev,
 	chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 		BIT(IIO_CHAN_INFO_SCALE);
 
+	if (rescale->offset)
+		chan->info_mask_separate |= BIT(IIO_CHAN_INFO_OFFSET);
+
 	/*
 	 * Using .read_avail() is fringe to begin with and makes no sense
 	 * whatsoever for processed channels, so we make sure that this cannot
@@ -352,6 +431,7 @@ static int rescale_probe(struct platform_device *pdev)
 	rescale->cfg = of_device_get_match_data(dev);
 	rescale->numerator = 1;
 	rescale->denominator = 1;
+	rescale->offset = 0;
 
 	ret = rescale->cfg->props(dev, rescale);
 	if (ret)
diff --git a/include/linux/iio/afe/rescale.h b/include/linux/iio/afe/rescale.h
index 14d4ee1227c6..b152ac487403 100644
--- a/include/linux/iio/afe/rescale.h
+++ b/include/linux/iio/afe/rescale.h
@@ -23,8 +23,12 @@ struct rescale {
 	bool chan_processed;
 	s32 numerator;
 	s32 denominator;
+	s32 offset;
 };
 
 int rescale_process_scale(struct rescale *rescale, int scale_type,
 			  int *val, int *val2);
+int rescale_process_offset(struct rescale *rescale, int scale_type,
+			   int scale, int scale2, int schan_off,
+			   int *val, int *val2);
 #endif /* __IIO_RESCALE_H__ */
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 07/14] iio: afe: rescale: use s64 for temporary scale calculations
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (5 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 06/14] iio: afe: rescale: add offset support Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 08/14] iio: afe: rescale: fix accuracy for small fractional scales Liam Beguin
                   ` (7 subsequent siblings)
  14 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

All four scaling coefficients can take signed values.
Make tmp a signed 64-bit integer and switch to div_s64() to preserve
signs during 64-bit divisions.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/afe/iio-rescale.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index e88b63747a46..e3680998565e 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -22,7 +22,7 @@
 int rescale_process_scale(struct rescale *rescale, int scale_type,
 			  int *val, int *val2)
 {
-	unsigned long long tmp;
+	s64 tmp;
 	s32 rem;
 	u32 mult;
 	u32 neg;
@@ -39,10 +39,10 @@ int rescale_process_scale(struct rescale *rescale, int scale_type,
 		*val2 = rescale->denominator;
 		return IIO_VAL_FRACTIONAL;
 	case IIO_VAL_FRACTIONAL_LOG2:
-		tmp = *val * 1000000000LL;
-		do_div(tmp, rescale->denominator);
+		tmp = (s64)*val * 1000000000LL;
+		tmp = div_s64(tmp, rescale->denominator);
 		tmp *= rescale->numerator;
-		do_div(tmp, 1000000000LL);
+		tmp = div_s64(tmp, 1000000000LL);
 		*val = tmp;
 		return scale_type;
 	case IIO_VAL_INT_PLUS_NANO:
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 08/14] iio: afe: rescale: fix accuracy for small fractional scales
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (6 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 07/14] iio: afe: rescale: use s64 for temporary scale calculations Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 09/14] iio: afe: rescale: reduce risk of integer overflow Liam Beguin
                   ` (6 subsequent siblings)
  14 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

The approximation caused by integer divisions can be costly on smaller
scale values since the decimal part is significant compared to the
integer part. Switch to an IIO_VAL_INT_PLUS_NANO scale type in such
cases to maintain accuracy.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/afe/iio-rescale.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index e3680998565e..66306477aeab 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -23,7 +23,7 @@ int rescale_process_scale(struct rescale *rescale, int scale_type,
 			  int *val, int *val2)
 {
 	s64 tmp;
-	s32 rem;
+	s32 rem, rem2;
 	u32 mult;
 	u32 neg;
 
@@ -42,9 +42,23 @@ int rescale_process_scale(struct rescale *rescale, int scale_type,
 		tmp = (s64)*val * 1000000000LL;
 		tmp = div_s64(tmp, rescale->denominator);
 		tmp *= rescale->numerator;
-		tmp = div_s64(tmp, 1000000000LL);
+
+		tmp = div_s64_rem(tmp, 1000000000LL, &rem);
 		*val = tmp;
-		return scale_type;
+
+		if (!rem)
+			return scale_type;
+
+		tmp = 1 << *val2;
+
+		rem2 = *val % (int)tmp;
+		*val = *val / (int)tmp;
+
+		*val2 = rem / (int)tmp;
+		if (rem2)
+			*val2 += div_s64((s64)rem2 * 1000000000LL, tmp);
+
+		return IIO_VAL_INT_PLUS_NANO;
 	case IIO_VAL_INT_PLUS_NANO:
 	case IIO_VAL_INT_PLUS_MICRO:
 		mult = scale_type == IIO_VAL_INT_PLUS_NANO ? NANO : MICRO;
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 09/14] iio: afe: rescale: reduce risk of integer overflow
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (7 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 08/14] iio: afe: rescale: fix accuracy for small fractional scales Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 10/14] iio: test: add basic tests for the iio-rescale driver Liam Beguin
                   ` (5 subsequent siblings)
  14 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

Reduce the risk of integer overflow by doing the scale calculation on
a 64-bit integer. Since the rescaling is only performed on *val, reuse
the IIO_VAL_FRACTIONAL_LOG2 case.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/afe/iio-rescale.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index 66306477aeab..4ab19a730a57 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -23,21 +23,31 @@ int rescale_process_scale(struct rescale *rescale, int scale_type,
 			  int *val, int *val2)
 {
 	s64 tmp;
+	int _val, _val2;
 	s32 rem, rem2;
 	u32 mult;
 	u32 neg;
 
 	switch (scale_type) {
-	case IIO_VAL_FRACTIONAL:
-		*val *= rescale->numerator;
-		*val2 *= rescale->denominator;
-		return scale_type;
 	case IIO_VAL_INT:
 		*val *= rescale->numerator;
 		if (rescale->denominator == 1)
 			return scale_type;
 		*val2 = rescale->denominator;
 		return IIO_VAL_FRACTIONAL;
+	case IIO_VAL_FRACTIONAL:
+		/*
+		 * When the product of both scales doesn't overflow, avoid
+		 * potential accuracy loss (for in kernel consumers) by
+		 * keeping a fractional representation.
+		 */
+		if (!check_mul_overflow(*val, rescale->numerator, &_val) &&
+		    !check_mul_overflow(*val2, rescale->denominator, &_val2)) {
+			*val = _val;
+			*val2 = _val2;
+			return IIO_VAL_FRACTIONAL;
+		}
+		fallthrough;
 	case IIO_VAL_FRACTIONAL_LOG2:
 		tmp = (s64)*val * 1000000000LL;
 		tmp = div_s64(tmp, rescale->denominator);
@@ -49,7 +59,10 @@ int rescale_process_scale(struct rescale *rescale, int scale_type,
 		if (!rem)
 			return scale_type;
 
-		tmp = 1 << *val2;
+		if (scale_type == IIO_VAL_FRACTIONAL)
+			tmp = *val2;
+		else
+			tmp = 1 << *val2;
 
 		rem2 = *val % (int)tmp;
 		*val = *val / (int)tmp;
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 10/14] iio: test: add basic tests for the iio-rescale driver
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (8 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 09/14] iio: afe: rescale: reduce risk of integer overflow Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-21  7:09   ` kernel test robot
  2021-12-21  8:03   ` kernel test robot
  2021-12-19 22:39 ` [PATCH v10 11/14] iio: afe: rescale: add RTD temperature sensor support Liam Beguin
                   ` (4 subsequent siblings)
  14 siblings, 2 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

The iio-rescale driver supports various combinations of scale types and
offsets. These can often result in large integer multiplications. Make
sure these calculations are done right by adding a set of kunit test
cases that build on top of iio-test-format.

To run these tests, add the following to .kunitconfig
	$ cat .kunitconfig
	CONFIG_IIO=y
	CONFIG_IIO_RESCALE_KUNIT_TEST=y
	CONFIG_KUNIT=y

Then run:
	$ ./tools/testing/kunit/kunit.py run --kunitconfig .kunitconfig

Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/test/Kconfig            |  10 +
 drivers/iio/test/Makefile           |   1 +
 drivers/iio/test/iio-test-rescale.c | 705 ++++++++++++++++++++++++++++
 3 files changed, 716 insertions(+)
 create mode 100644 drivers/iio/test/iio-test-rescale.c

diff --git a/drivers/iio/test/Kconfig b/drivers/iio/test/Kconfig
index 679a7794af20..872ed4ed140a 100644
--- a/drivers/iio/test/Kconfig
+++ b/drivers/iio/test/Kconfig
@@ -4,6 +4,16 @@
 #
 
 # Keep in alphabetical order
+config IIO_RESCALE_KUNIT_TEST
+	bool "Test IIO rescale conversion functions"
+	depends on KUNIT && !IIO_RESCALE
+	default KUNIT_ALL_TESTS
+	help
+	  If you want to run tests on the iio-rescale code say Y here.
+
+	  This takes advantage of ARCH=um to run tests and should be used by
+	  developers to tests their changes to the rescaling logic.
+
 config IIO_TEST_FORMAT
         bool "Test IIO formatting functions"
         depends on KUNIT=y
diff --git a/drivers/iio/test/Makefile b/drivers/iio/test/Makefile
index 467519a2027e..f15ae0a6394f 100644
--- a/drivers/iio/test/Makefile
+++ b/drivers/iio/test/Makefile
@@ -4,5 +4,6 @@
 #
 
 # Keep in alphabetical order
+obj-$(CONFIG_IIO_RESCALE_KUNIT_TEST) += iio-test-rescale.o ../afe/iio-rescale.o
 obj-$(CONFIG_IIO_TEST_FORMAT) += iio-test-format.o
 CFLAGS_iio-test-format.o += $(DISABLE_STRUCTLEAK_PLUGIN)
diff --git a/drivers/iio/test/iio-test-rescale.c b/drivers/iio/test/iio-test-rescale.c
new file mode 100644
index 000000000000..526f87fa3514
--- /dev/null
+++ b/drivers/iio/test/iio-test-rescale.c
@@ -0,0 +1,705 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Kunit tests for IIO rescale conversions
+ *
+ * Copyright (c) 2021 Liam Beguin <liambeguin@gmail.com>
+ */
+
+#include <kunit/test.h>
+#include <linux/gcd.h>
+#include <linux/iio/afe/rescale.h>
+#include <linux/iio/iio.h>
+#include <linux/overflow.h>
+
+struct rescale_tc_data {
+	const char *name;
+
+	const s32 numerator;
+	const s32 denominator;
+	const s32 offset;
+
+	const int schan_val;
+	const int schan_val2;
+	const int schan_off;
+	const int schan_scale_type;
+
+	const char *expected;
+	const char *expected_off;
+};
+
+const struct rescale_tc_data scale_cases[] = {
+	/*
+	 * Typical use cases
+	 */
+	{
+		.name = "typical IIO_VAL_INT, positive",
+		.numerator = 1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT,
+		.schan_val = 42,
+		.expected = "5210.918114143",
+	},
+	{
+		.name = "typical IIO_VAL_INT, negative",
+		.numerator = -1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT,
+		.schan_val = 42,
+		.expected = "-5210.918114143",
+	},
+	{
+		.name = "typical IIO_VAL_FRACTIONAL, positive",
+		.numerator = 1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 42,
+		.schan_val2 = 20,
+		.expected = "260.545905707",
+	},
+	{
+		.name = "typical IIO_VAL_FRACTIONAL, negative",
+		.numerator = -1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 42,
+		.schan_val2 = 20,
+		.expected = "-260.545905707",
+	},
+	{
+		.name = "typical IIO_VAL_FRACTIONAL_LOG2, positive",
+		.numerator = 42,
+		.denominator = 53,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = 4096,
+		.schan_val2 = 16,
+		.expected = "0.049528301",
+	},
+	{
+		.name = "typical IIO_VAL_FRACTIONAL_LOG2, negative",
+		.numerator = -42,
+		.denominator = 53,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = 4096,
+		.schan_val2 = 16,
+		.expected = "-0.049528301",
+	},
+	{
+		.name = "typical IIO_VAL_INT_PLUS_NANO, positive",
+		.numerator = 1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = 10,
+		.schan_val2 = 123456,
+		.expected = "1240.710106203",
+	},
+	{
+		.name = "typical IIO_VAL_INT_PLUS_NANO, negative",
+		.numerator = -1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = 10,
+		.schan_val2 = 123456,
+		.expected = "-1240.710106203",
+	},
+	{
+		.name = "typical IIO_VAL_INT_PLUS_MICRO, positive",
+		.numerator = 1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = 10,
+		.schan_val2 = 1234,
+		.expected = "1240.84789",
+	},
+	{
+		.name = "typical IIO_VAL_INT_PLUS_MICRO, negative",
+		.numerator = -1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = 10,
+		.schan_val2 = 1234,
+		.expected = "-1240.84789",
+	},
+	/*
+	 * Use cases with small scales involving divisions
+	 */
+	{
+		.name = "small IIO_VAL_FRACTIONAL, 261/509 scaled by 90/1373754273",
+		.numerator = 261,
+		.denominator = 509,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 90,
+		.schan_val2 = 1373754273,
+		.expected = "0.000000033594",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL, 90/1373754273 scaled by 261/509",
+		.numerator = 90,
+		.denominator = 1373754273,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 261,
+		.schan_val2 = 509,
+		.expected = "0.000000033594",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL, 760/1373754273 scaled by 427/2727",
+		.numerator = 760,
+		.denominator = 1373754273,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 427,
+		.schan_val2 = 2727,
+		.expected = "0.000000086626",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL, 761/1373754273 scaled by 427/2727",
+		.numerator = 761,
+		.denominator = 1373754273,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 427,
+		.schan_val2 = 2727,
+		.expected = "0.000000086740",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL, 5/32768 scaled by 3/10000",
+		.numerator = 5,
+		.denominator = 32768,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 3,
+		.schan_val2 = 10000,
+		.expected = "0.0000000457763671875",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL, 0 < scale < 1",
+		.numerator = 6,
+		.denominator = 6,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 1,
+		.schan_val2 = 3,
+		.expected = "0.3333333333333333",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL, -1 < scale < 0",
+		.numerator = -6,
+		.denominator = 6,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 1,
+		.schan_val2 = 3,
+		.expected = "-0.3333333333333333",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL, 0 < scale < 2",
+		.numerator = 8,
+		.denominator = 2,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 1,
+		.schan_val2 = 3,
+		.expected = "1.3333333333333333",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL, -2 < scale < 0",
+		.numerator = -8,
+		.denominator = 2,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 1,
+		.schan_val2 = 3,
+		.expected = "-1.3333333333333333",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL_LOG2, 760/32768 scaled by 15/22",
+		.numerator = 760,
+		.denominator = 32768,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = 15,
+		.schan_val2 = 22,
+		.expected = "0.000000082946",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL_LOG2, 761/32768 scaled by 15/22",
+		.numerator = 761,
+		.denominator = 32768,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = 15,
+		.schan_val2 = 22,
+		.expected = "0.000000083055",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL_LOG2, 0 < scale < 1",
+		.numerator = 16,
+		.denominator = 3,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = 1,
+		.schan_val2 = 4,
+		.expected = "0.3333333333333333",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL_LOG2, -1 < scale < 0",
+		.numerator = -16,
+		.denominator = 3,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = 1,
+		.schan_val2 = 4,
+		.expected = "-0.3333333333333333",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL_LOG2, 0 < scale < 2",
+		.numerator = 8,
+		.denominator = 3,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = 1,
+		.schan_val2 = 1,
+		.expected = "1.3333333333333333",
+	},
+	{
+		.name = "small IIO_VAL_FRACTIONAL_LOG2, -2 < scale < 0",
+		.numerator = -8,
+		.denominator = 3,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = 1,
+		.schan_val2 = 1,
+		.expected = "-1.3333333333333333",
+	},
+	{
+		.name = "small IIO_VAL_INT_PLUS_MICRO, positive",
+		.numerator = 1,
+		.denominator = 2,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = 5,
+		.schan_val2 = 1234,
+		.expected = "2.500617",
+	},
+	{
+		.name = "small IIO_VAL_INT_PLUS_MICRO, negative",
+		.numerator = -1,
+		.denominator = 2,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = 5,
+		.schan_val2 = 1234,
+		.expected = "-2.500617",
+	},
+	/*
+	 * INT_PLUS_{MICRO,NANO} positive/negative corner cases
+	 */
+	{
+		.name = "negative IIO_VAL_INT_PLUS_NANO, negative schan",
+		.numerator = 1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = -10,
+		.schan_val2 = 123456,
+		.expected = "-1240.710106203",
+	},
+	{
+		.name = "negative IIO_VAL_INT_PLUS_NANO, both negative",
+		.numerator = -1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = -10,
+		.schan_val2 = 123456,
+		.expected = "1240.710106203",
+	},
+	{
+		.name = "negative IIO_VAL_INT_PLUS_NANO, 3 negative",
+		.numerator = -1000000,
+		.denominator = -8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = -10,
+		.schan_val2 = 123456,
+		.expected = "-1240.710106203",
+	},
+	{
+		.name = "negative IIO_VAL_INT_PLUS_NANO, 4 negative",
+		.numerator = -1000000,
+		.denominator = -8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = -10,
+		.schan_val2 = -123456,
+		.expected = "-1240.710106203",
+	},
+	{
+		.name = "negative IIO_VAL_INT_PLUS_NANO, negative, *val = 0",
+		.numerator = 1,
+		.denominator = -10,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = 0,
+		.schan_val2 = 123456789,
+		.expected = "-0.012345678",
+	},
+	/*
+	 * INT_PLUS_{MICRO,NANO} decimal part overflow
+	 */
+	{
+		.name = "decimal overflow IIO_VAL_INT_PLUS_NANO, positive",
+		.numerator = 1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = 10,
+		.schan_val2 = 123456789,
+		.expected = "1256.01200856",
+	},
+	{
+		.name = "decimal overflow IIO_VAL_INT_PLUS_NANO, negative",
+		.numerator = -1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = 10,
+		.schan_val2 = 123456789,
+		.expected = "-1256.01200856",
+	},
+	{
+		.name = "decimal overflow IIO_VAL_INT_PLUS_NANO, negative schan",
+		.numerator = 1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = -10,
+		.schan_val2 = 123456789,
+		.expected = "-1256.01200856",
+	},
+	{
+		.name = "decimal overflow IIO_VAL_INT_PLUS_MICRO, positive",
+		.numerator = 1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = 10,
+		.schan_val2 = 123456789,
+		.expected = "16557.914267",
+	},
+	{
+		.name = "decimal overflow IIO_VAL_INT_PLUS_MICRO, negative",
+		.numerator = -1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = 10,
+		.schan_val2 = 123456789,
+		.expected = "-16557.914267",
+	},
+	{
+		.name = "decimal overflow IIO_VAL_INT_PLUS_MICRO, negative schan",
+		.numerator = 1000000,
+		.denominator = 8060,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = -10,
+		.schan_val2 = 123456789,
+		.expected = "-16557.914267",
+	},
+	/*
+	 * 32-bit overflow conditions
+	 */
+	{
+		.name = "overflow IIO_VAL_FRACTIONAL, positive",
+		.numerator = 2,
+		.denominator = 20,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = S32_MAX,
+		.schan_val2 = 1,
+		.expected = "214748364.7",
+	},
+	{
+		.name = "overflow IIO_VAL_FRACTIONAL, negative",
+		.numerator = -2,
+		.denominator = 20,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = S32_MAX,
+		.schan_val2 = 1,
+		.expected = "-214748364.7",
+	},
+	{
+		.name = "overflow IIO_VAL_FRACTIONAL_LOG2, positive",
+		.numerator = S32_MAX,
+		.denominator = 4096,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = 4096,
+		.schan_val2 = 16,
+		.expected = "32767.99998474121",
+	},
+	{
+		.name = "overflow IIO_VAL_FRACTIONAL_LOG2, negative",
+		.numerator = S32_MAX,
+		.denominator = 4096,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = -4096,
+		.schan_val2 = 16,
+		.expected = "-32767.99998474121",
+	},
+	{
+		.name = "overflow IIO_VAL_INT_PLUS_NANO, positive",
+		.numerator = 2,
+		.denominator = 20,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = 10,
+		.schan_val2 = S32_MAX,
+		.expected = "1.214748364",
+	},
+	{
+		.name = "overflow IIO_VAL_INT_PLUS_NANO, negative",
+		.numerator = -2,
+		.denominator = 20,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = 10,
+		.schan_val2 = S32_MAX,
+		.expected = "-1.214748364",
+	},
+	{
+		.name = "overflow IIO_VAL_INT_PLUS_NANO, negative schan",
+		.numerator = 2,
+		.denominator = 20,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = -10,
+		.schan_val2 = S32_MAX,
+		.expected = "-1.214748364",
+	},
+	{
+		.name = "overflow IIO_VAL_INT_PLUS_MICRO, positive",
+		.numerator = 2,
+		.denominator = 20,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = 10,
+		.schan_val2 = S32_MAX,
+		.expected = "215.748364",
+	},
+	{
+		.name = "overflow IIO_VAL_INT_PLUS_MICRO, negative",
+		.numerator = -2,
+		.denominator = 20,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = 10,
+		.schan_val2 = S32_MAX,
+		.expected = "-215.748364",
+	},
+	{
+		.name = "overflow IIO_VAL_INT_PLUS_MICRO, negative schan",
+		.numerator = 2,
+		.denominator = 20,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = -10,
+		.schan_val2 = S32_MAX,
+		.expected = "-215.748364",
+	},
+};
+
+const struct rescale_tc_data offset_cases[] = {
+	/*
+	 * Typical use cases
+	 */
+	{
+		.name = "typical IIO_VAL_INT, positive",
+		.offset = 1234,
+		.schan_scale_type = IIO_VAL_INT,
+		.schan_val = 123,
+		.schan_val2 = 0,
+		.schan_off = 14,
+		.expected_off = "24", /* 23.872 */
+	},
+	{
+		.name = "typical IIO_VAL_INT, negative",
+		.offset = -1234,
+		.schan_scale_type = IIO_VAL_INT,
+		.schan_val = 12,
+		.schan_val2 = 0,
+		.schan_off = 14,
+		.expected_off = "-88", /* -88.83333333333333 */
+	},
+	{
+		.name = "typical IIO_VAL_FRACTIONAL, positive",
+		.offset = 1234,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 12,
+		.schan_val2 = 34,
+		.schan_off = 14,
+		.expected_off = "3510", /* 3510.333333333333 */
+	},
+	{
+		.name = "typical IIO_VAL_FRACTIONAL, negative",
+		.offset = -1234,
+		.schan_scale_type = IIO_VAL_FRACTIONAL,
+		.schan_val = 12,
+		.schan_val2 = 34,
+		.schan_off = 14,
+		.expected_off = "-3482", /* -3482.333333333333 */
+	},
+	{
+		.name = "typical IIO_VAL_FRACTIONAL_LOG2, positive",
+		.offset = 1234,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = 12,
+		.schan_val2 = 16,
+		.schan_off = 14,
+		.expected_off = "6739299", /* 6739299.333333333 */
+	},
+	{
+		.name = "typical IIO_VAL_FRACTIONAL_LOG2, negative",
+		.offset = -1234,
+		.schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+		.schan_val = 12,
+		.schan_val2 = 16,
+		.schan_off = 14,
+		.expected_off = "-6739271", /* -6739271.333333333 */
+	},
+	{
+		.name = "typical IIO_VAL_INT_PLUS_NANO, positive",
+		.offset = 1234,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = 10,
+		.schan_val2 = 123456789,
+		.schan_off = 14,
+		.expected_off = "135", /* 135.8951219647469 */
+	},
+	{
+		.name = "typical IIO_VAL_INT_PLUS_NANO, negative",
+		.offset = -1234,
+		.schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+		.schan_val = 10,
+		.schan_val2 = 123456789,
+		.schan_off = 14,
+		.expected_off = "-107", /* -107.89512196474689 */
+	},
+	{
+		.name = "typical IIO_VAL_INT_PLUS_MICRO, positive",
+		.offset = 1234,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = 10,
+		.schan_val2 = 123456789,
+		.schan_off = 14,
+		.expected_off = "23", /* 23.246438560723952 */
+	},
+	{
+		.name = "typical IIO_VAL_INT_PLUS_MICRO, negative",
+		.offset = -12345,
+		.schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+		.schan_val = 10,
+		.schan_val2 = 123456789,
+		.schan_off = 14,
+		.expected_off = "-78", /* -78.50185091745313 */
+	},
+};
+
+static void case_to_desc(const struct rescale_tc_data *t, char *desc)
+{
+	strcpy(desc, t->name);
+}
+
+KUNIT_ARRAY_PARAM(iio_rescale_scale, scale_cases, case_to_desc);
+KUNIT_ARRAY_PARAM(iio_rescale_offset, offset_cases, case_to_desc);
+
+/**
+ * iio_str_to_nano() - Parse a fixed-point string to get an
+ *                      IIO_VAL_INT_PLUS_NANO value
+ * @str: The string to parse
+ * @nano: The number as an integer
+ *
+ * Returns 0 on success, or a negative error code if the string cound not be
+ * parsed.
+ */
+static int iio_str_to_nano(const char *str, s64 *nano)
+{
+	int fract_mult = 100000000LL;
+	int tmp, tmp2;
+	int ret = 0;
+
+	ret = iio_str_to_fixpoint(str, fract_mult, &tmp, &tmp2);
+	if (ret < 0)
+		return ret;
+
+	if (tmp < 0)
+		tmp2 *= -1;
+
+	*nano = (s64)tmp * 10 * fract_mult + tmp2;
+
+	return ret;
+}
+
+/**
+ * iio_test_relative_error_ppm() - Compute relative error (in parts-per-million)
+ *                                 between two fixed-point strings
+ * @real_str: The real value as a string
+ * @exp_str: The expected value as a string
+ *
+ * Returns a negative error code if the strings cound not be parsed, or the
+ * relative error in parts-per-million.
+ */
+static int iio_test_relative_error_ppm(const char *real_str, const char *exp_str)
+{
+	s64 real, exp, err;
+	int ret;
+
+	ret = iio_str_to_nano(real_str, &real);
+	if (ret < 0)
+		return ret;
+
+	ret = iio_str_to_nano(exp_str, &exp);
+	if (ret < 0)
+		return ret;
+
+	if (!exp) {
+		pr_err("Expected value is null, relative error is undefined\n");
+		return -EINVAL;
+	}
+
+	err = 1000000 * abs(exp - real);
+	err = div64_u64(err, abs(exp));
+	return (int)err;
+}
+
+static void iio_rescale_test_scale(struct kunit *test)
+{
+	struct rescale_tc_data *t = (struct rescale_tc_data *)test->param_value;
+	char *buff = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
+	struct rescale rescale;
+	int values[2];
+	int rel_ppm;
+	int ret;
+
+	rescale.numerator = t->numerator;
+	rescale.denominator = t->denominator;
+	rescale.offset = t->offset;
+	values[0] = t->schan_val;
+	values[1] = t->schan_val2;
+
+	ret = rescale_process_scale(&rescale, t->schan_scale_type,
+				    &values[0], &values[1]);
+
+	ret = iio_format_value(buff, ret, 2, values);
+	KUNIT_EXPECT_EQ(test, (int)strlen(buff), ret);
+
+	rel_ppm = iio_test_relative_error_ppm(buff, t->expected);
+	KUNIT_EXPECT_GE_MSG(test, rel_ppm, 0, "failed to compute ppm\n");
+
+	KUNIT_EXPECT_EQ_MSG(test, rel_ppm, 0,
+			    "\t    real=%s"
+			    "\texpected=%s\n",
+			    buff, t->expected);
+}
+
+static void iio_rescale_test_offset(struct kunit *test)
+{
+	struct rescale_tc_data *t = (struct rescale_tc_data *)test->param_value;
+	char *buff_off = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
+	struct rescale rescale;
+	int values[2];
+	int ret;
+
+	rescale.numerator = t->numerator;
+	rescale.denominator = t->denominator;
+	rescale.offset = t->offset;
+	values[0] = t->schan_val;
+	values[1] = t->schan_val2;
+
+	ret = rescale_process_offset(&rescale, t->schan_scale_type,
+				     t->schan_val, t->schan_val2, t->schan_off,
+				     &values[0], &values[1]);
+
+	ret = iio_format_value(buff_off, ret, 2, values);
+	KUNIT_EXPECT_EQ(test, (int)strlen(buff_off), ret);
+
+	KUNIT_EXPECT_STREQ(test, strim(buff_off), t->expected_off);
+}
+
+static struct kunit_case iio_rescale_test_cases[] = {
+	KUNIT_CASE_PARAM(iio_rescale_test_scale, iio_rescale_scale_gen_params),
+	KUNIT_CASE_PARAM(iio_rescale_test_offset, iio_rescale_offset_gen_params),
+	{}
+};
+
+static struct kunit_suite iio_rescale_test_suite = {
+	.name = "iio-rescale",
+	.test_cases = iio_rescale_test_cases,
+};
+kunit_test_suite(iio_rescale_test_suite);
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 11/14] iio: afe: rescale: add RTD temperature sensor support
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (9 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 10/14] iio: test: add basic tests for the iio-rescale driver Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 12/14] iio: afe: rescale: add temperature transducers Liam Beguin
                   ` (3 subsequent siblings)
  14 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

An RTD (Resistance Temperature Detector) is a kind of temperature
sensor used to get a linear voltage to temperature reading within a
give range (usually 0 to 100 degrees Celsius). Common types of RTDs
include PT100, PT500, and PT1000.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/afe/iio-rescale.c | 48 +++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index 4ab19a730a57..cde39432196a 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -393,10 +393,52 @@ static int rescale_voltage_divider_props(struct device *dev,
 	return 0;
 }
 
+static int rescale_temp_sense_rtd_props(struct device *dev,
+					struct rescale *rescale)
+{
+	u32 factor;
+	u32 alpha;
+	u32 iexc;
+	u32 tmp;
+	int ret;
+	u32 r0;
+
+	ret = device_property_read_u32(dev, "excitation-current-microamp",
+				       &iexc);
+	if (ret) {
+		dev_err(dev, "failed to read excitation-current-microamp: %d\n",
+			ret);
+		return ret;
+	}
+
+	ret = device_property_read_u32(dev, "alpha-ppm-per-celsius", &alpha);
+	if (ret) {
+		dev_err(dev, "failed to read alpha-ppm-per-celsius: %d\n",
+			ret);
+		return ret;
+	}
+
+	ret = device_property_read_u32(dev, "r-naught-ohms", &r0);
+	if (ret) {
+		dev_err(dev, "failed to read r-naught-ohms: %d\n", ret);
+		return ret;
+	}
+
+	tmp = r0 * iexc * alpha / 1000000;
+	factor = gcd(tmp, 1000000);
+	rescale->numerator = 1000000 / factor;
+	rescale->denominator = tmp / factor;
+
+	rescale->offset = -1 * ((r0 * iexc) / 1000);
+
+	return 0;
+}
+
 enum rescale_variant {
 	CURRENT_SENSE_AMPLIFIER,
 	CURRENT_SENSE_SHUNT,
 	VOLTAGE_DIVIDER,
+	TEMP_SENSE_RTD,
 };
 
 static const struct rescale_cfg rescale_cfg[] = {
@@ -412,6 +454,10 @@ static const struct rescale_cfg rescale_cfg[] = {
 		.type = IIO_VOLTAGE,
 		.props = rescale_voltage_divider_props,
 	},
+	[TEMP_SENSE_RTD] = {
+		.type = IIO_TEMP,
+		.props = rescale_temp_sense_rtd_props,
+	},
 };
 
 static const struct of_device_id rescale_match[] = {
@@ -421,6 +467,8 @@ static const struct of_device_id rescale_match[] = {
 	  .data = &rescale_cfg[CURRENT_SENSE_SHUNT], },
 	{ .compatible = "voltage-divider",
 	  .data = &rescale_cfg[VOLTAGE_DIVIDER], },
+	{ .compatible = "temperature-sense-rtd",
+	  .data = &rescale_cfg[TEMP_SENSE_RTD], },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, rescale_match);
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 12/14] iio: afe: rescale: add temperature transducers
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (10 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 11/14] iio: afe: rescale: add RTD temperature sensor support Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 13/14] dt-bindings: iio: afe: add bindings for temperature-sense-rtd Liam Beguin
                   ` (2 subsequent siblings)
  14 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

A temperature transducer is a device that converts a thermal quantity
into any other physical quantity. This patch add support for temperature
to voltage (like the LTC2997) and temperature to current (like the
AD590) linear transducers.
In both cases these are assumed to be connected to a voltage ADC.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/afe/iio-rescale.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index cde39432196a..486eb80f89d7 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -434,11 +434,37 @@ static int rescale_temp_sense_rtd_props(struct device *dev,
 	return 0;
 }
 
+static int rescale_temp_transducer_props(struct device *dev,
+					 struct rescale *rescale)
+{
+	s32 offset = 0;
+	s32 sense = 1;
+	s32 alpha;
+	int ret;
+
+	device_property_read_u32(dev, "sense-offset-millicelsius", &offset);
+	device_property_read_u32(dev, "sense-resistor-ohms", &sense);
+	ret = device_property_read_u32(dev, "alpha-ppm-per-celsius", &alpha);
+	if (ret) {
+		dev_err(dev, "failed to read alpha-ppm-per-celsius: %d\n", ret);
+		return ret;
+	}
+
+	rescale->numerator = 1000000;
+	rescale->denominator = alpha * sense;
+
+	rescale->offset = div_s64((s64)offset * rescale->denominator,
+				  rescale->numerator);
+
+	return 0;
+}
+
 enum rescale_variant {
 	CURRENT_SENSE_AMPLIFIER,
 	CURRENT_SENSE_SHUNT,
 	VOLTAGE_DIVIDER,
 	TEMP_SENSE_RTD,
+	TEMP_TRANSDUCER,
 };
 
 static const struct rescale_cfg rescale_cfg[] = {
@@ -458,6 +484,10 @@ static const struct rescale_cfg rescale_cfg[] = {
 		.type = IIO_TEMP,
 		.props = rescale_temp_sense_rtd_props,
 	},
+	[TEMP_TRANSDUCER] = {
+		.type = IIO_TEMP,
+		.props = rescale_temp_transducer_props,
+	},
 };
 
 static const struct of_device_id rescale_match[] = {
@@ -469,6 +499,8 @@ static const struct of_device_id rescale_match[] = {
 	  .data = &rescale_cfg[VOLTAGE_DIVIDER], },
 	{ .compatible = "temperature-sense-rtd",
 	  .data = &rescale_cfg[TEMP_SENSE_RTD], },
+	{ .compatible = "temperature-transducer",
+	  .data = &rescale_cfg[TEMP_TRANSDUCER], },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, rescale_match);
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 13/14] dt-bindings: iio: afe: add bindings for temperature-sense-rtd
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (11 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 12/14] iio: afe: rescale: add temperature transducers Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-19 22:39 ` [PATCH v10 14/14] dt-bindings: iio: afe: add bindings for temperature transducers Liam Beguin
  2021-12-20 21:37 ` [PATCH v10 00/14] iio: afe: add temperature rescaling support Peter Rosin
  14 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

An ADC is often used to measure other quantities indirectly. This
binding describe one case, the measurement of a temperature through the
voltage across an RTD resistor such as a PT1000.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../iio/afe/temperature-sense-rtd.yaml        | 101 ++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml

diff --git a/Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml b/Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml
new file mode 100644
index 000000000000..336ce96371db
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml
@@ -0,0 +1,101 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/afe/temperature-sense-rtd.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Temperature Sense RTD
+
+maintainers:
+  - Liam Beguin <liambeguin@gmail.com>
+
+description: |
+  RTDs (Resistance Temperature Detectors) are a kind of temperature sensors
+  used to get a linear voltage to temperature reading within a give range
+  (usually 0 to 100 degrees Celsius).
+
+  When an io-channel measures the output voltage across an RTD such as a
+  PT1000, the interesting measurement is almost always the corresponding
+  temperature, not the voltage output. This binding describes such a circuit.
+
+  The general transfer function here is (using SI units)
+
+    V = R(T) * iexc
+    R(T) = r0 * (1 + alpha * T)
+    T = 1 / (alpha * r0 * iexc) * (V - r0 * iexc)
+
+  The following circuit matches what's in the examples section.
+
+           5V0
+          -----
+            |
+        +---+----+
+        |  R 5k  |
+        +---+----+
+            |
+            V 1mA
+            |
+            +---- Vout
+            |
+        +---+----+
+        | PT1000 |
+        +---+----+
+            |
+          -----
+           GND
+
+properties:
+  compatible:
+    const: temperature-sense-rtd
+
+  io-channels:
+    maxItems: 1
+    description: |
+      Channel node of a voltage io-channel.
+
+  '#io-channel-cells':
+    const: 0
+
+  excitation-current-microamp:
+    description: The current fed through the RTD sensor.
+
+  alpha-ppm-per-celsius:
+    description: |
+      alpha can also be expressed in micro-ohms per ohm Celsius. It's a linear
+      approximation of the resistance versus temperature relationship
+      between 0 and 100 degrees Celsius.
+
+      alpha = (R_100 - R_0) / (100 * R_0)
+
+      Where, R_100 is the resistance of the sensor at 100 degrees Celsius, and
+      R_0 (or r-naught-ohms) is the resistance of the sensor at 0 degrees
+      Celsius.
+
+      Pure platinum has an alpha of 3925. Industry standards such as IEC60751
+      and ASTM E-1137 specify an alpha of 3850.
+
+  r-naught-ohms:
+    description: |
+      Resistance of the sensor at 0 degrees Celsius.
+      Common values are 100 for PT100, 500 for PT500, and 1000 for PT1000
+
+additionalProperties: false
+required:
+  - compatible
+  - io-channels
+  - excitation-current-microamp
+  - alpha-ppm-per-celsius
+  - r-naught-ohms
+
+examples:
+  - |
+    pt1000_1: temperature-sensor0 {
+        compatible = "temperature-sense-rtd";
+        #io-channel-cells = <0>;
+        io-channels = <&temp_adc1 0>;
+
+        excitation-current-microamp = <1000>; /* i = U/R = 5 / 5000 */
+        alpha-ppm-per-celsius = <3908>;
+        r-naught-ohms = <1000>;
+    };
+...
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* [PATCH v10 14/14] dt-bindings: iio: afe: add bindings for temperature transducers
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (12 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 13/14] dt-bindings: iio: afe: add bindings for temperature-sense-rtd Liam Beguin
@ 2021-12-19 22:39 ` Liam Beguin
  2021-12-20 21:37 ` [PATCH v10 00/14] iio: afe: add temperature rescaling support Peter Rosin
  14 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-19 22:39 UTC (permalink / raw)
  To: liambeguin, peda, jic23, lars
  Cc: linux-kernel, linux-iio, devicetree, robh+dt

From: Liam Beguin <lvb@xiphos.com>

An ADC is often used to measure other quantities indirectly.
This binding describe one case, the measurement of a temperature
through a temperature transducer (either voltage or current).

Signed-off-by: Liam Beguin <lvb@xiphos.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../iio/afe/temperature-transducer.yaml       | 114 ++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-transducer.yaml

diff --git a/Documentation/devicetree/bindings/iio/afe/temperature-transducer.yaml b/Documentation/devicetree/bindings/iio/afe/temperature-transducer.yaml
new file mode 100644
index 000000000000..cfbf5350db27
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/afe/temperature-transducer.yaml
@@ -0,0 +1,114 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/afe/temperature-transducer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Temperature Transducer
+
+maintainers:
+  - Liam Beguin <liambeguin@gmail.com>
+
+description: |
+  A temperature transducer is a device that converts a thermal quantity
+  into any other physical quantity. This binding applies to temperature to
+  voltage (like the LTC2997), and temperature to current (like the AD590)
+  linear transducers.
+  In both cases these are assumed to be connected to a voltage ADC.
+
+  When an io-channel measures the output voltage of a temperature analog front
+  end such as a temperature transducer, the interesting measurement is almost
+  always the corresponding temperature, not the voltage output. This binding
+  describes such a circuit.
+
+  The general transfer function here is (using SI units)
+    V(T) = Rsense * Isense(T)
+    T = (Isense(T) / alpha) + offset
+    T = 1 / (Rsense * alpha) * (V + offset * Rsense * alpha)
+
+  When using a temperature to voltage transducer, Rsense is set to 1.
+
+  The following circuits show a temperature to current and a temperature to
+  voltage transducer that can be used with this binding.
+
+           VCC
+          -----
+            |
+        +---+---+
+        | AD590 |                               VCC
+        +---+---+                              -----
+            |                                    |
+            V proportional to T             +----+----+
+            |                          D+ --+         |
+            +---- Vout                      | LTC2997 +--- Vout
+            |                          D- --+         |
+        +---+----+                          +---------+
+        | Rsense |                               |
+        +---+----+                             -----
+            |                                   GND
+          -----
+           GND
+
+properties:
+  compatible:
+    const: temperature-transducer
+
+  io-channels:
+    maxItems: 1
+    description: |
+      Channel node of a voltage io-channel.
+
+  '#io-channel-cells':
+    const: 0
+
+  sense-offset-millicelsius:
+    description: |
+      Temperature offset.
+      This offset is commonly used to convert from Kelvins to degrees Celsius.
+      In that case, sense-offset-millicelsius would be set to <(-273150)>.
+    default: 0
+
+  sense-resistor-ohms:
+    description: |
+      The sense resistor.
+      By default sense-resistor-ohms cancels out the resistor making the
+      circuit behave like a temperature transducer.
+    default: 1
+
+  alpha-ppm-per-celsius:
+    description: |
+      Sometimes referred to as output gain, slope, or temperature coefficient.
+
+      alpha is expressed in parts per million which can be micro-amps per
+      degrees Celsius or micro-volts per degrees Celsius. The is the main
+      characteristic of a temperature transducer and should be stated in the
+      datasheet.
+
+additionalProperties: false
+
+required:
+  - compatible
+  - io-channels
+  - alpha-ppm-per-celsius
+
+examples:
+  - |
+    ad950: temperature-sensor-0 {
+        compatible = "temperature-transducer";
+        #io-channel-cells = <0>;
+        io-channels = <&temp_adc 3>;
+
+        sense-offset-millicelsius = <(-273150)>; /* Kelvin to degrees Celsius */
+        sense-resistor-ohms = <8060>;
+        alpha-ppm-per-celsius = <1>; /* 1 uA/K */
+    };
+  - |
+    znq_tmp: temperature-sensor-1 {
+        compatible = "temperature-transducer";
+        #io-channel-cells = <0>;
+        io-channels = <&temp_adc 2>;
+
+        sense-offset-millicelsius = <(-273150)>; /* Kelvin to degrees Celsius */
+        alpha-ppm-per-celsius = <4000>; /* 4 mV/K */
+    };
+...
-- 
2.34.0


^ permalink raw reply related	[flat|nested] 23+ messages in thread

* Re: [PATCH v10 00/14] iio: afe: add temperature rescaling support
  2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
                   ` (13 preceding siblings ...)
  2021-12-19 22:39 ` [PATCH v10 14/14] dt-bindings: iio: afe: add bindings for temperature transducers Liam Beguin
@ 2021-12-20 21:37 ` Peter Rosin
  2021-12-22  3:29   ` Liam Beguin
  14 siblings, 1 reply; 23+ messages in thread
From: Peter Rosin @ 2021-12-20 21:37 UTC (permalink / raw)
  To: Liam Beguin, jic23, lars; +Cc: linux-kernel, linux-iio, devicetree, robh+dt

Hi!

On 2021-12-19 23:39, Liam Beguin wrote:
> Hi Jonathan, Peter,
> 
> I left out IIO_VAL_INT overflows for now, so that I can focus on getting
> the rest of these changes pulled in, but I don't mind adding a patch for
> that later on.
> 
> This series focuses on adding temperature rescaling support to the IIO
> Analog Front End (AFE) driver.
> 
> The first few patches address minor bugs in IIO inkernel functions, and
> prepare the AFE driver for the additional features.
> 
> The main changes to the AFE driver include an initial Kunit test suite,
> support for IIO_VAL_INT_PLUS_{NANO,MICRO} scales, and support for RTDs
> and temperature transducer sensors.
> 
> Thanks for your time,
> Liam

And thanks for your time and persistence!

This now looks in good order, so for the whole series:

Reviewed-by: Peter Rosin <peda@axentia.se>

Cheers,
Peter

^ permalink raw reply	[flat|nested] 23+ messages in thread

* Re: [PATCH v10 03/14] iio: inkern: make a best effort on offset calculation
  2021-12-19 22:39 ` [PATCH v10 03/14] iio: inkern: make a best effort on offset calculation Liam Beguin
@ 2021-12-21  5:42   ` Andy Shevchenko
  2021-12-21 17:50     ` Liam Beguin
  0 siblings, 1 reply; 23+ messages in thread
From: Andy Shevchenko @ 2021-12-21  5:42 UTC (permalink / raw)
  To: Liam Beguin
  Cc: Peter Rosin, Jonathan Cameron, Lars-Peter Clausen,
	Linux Kernel Mailing List, linux-iio, devicetree, Rob Herring

On Mon, Dec 20, 2021 at 11:17 AM Liam Beguin <liambeguin@gmail.com> wrote:
>
> 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.

...

> +                       offset_val /= (1 << offset_val2);

Besides potentially being problematic (if arg is 31 for the left
shift) why not simply

_val >>= _val2;

?

-- 
With Best Regards,
Andy Shevchenko

^ permalink raw reply	[flat|nested] 23+ messages in thread

* Re: [PATCH v10 04/14] iio: afe: rescale: expose scale processing function
       [not found]   ` <CAHp75VdfPf6FMvkGqhhQg5e5XE1cgE-K8seobe5n0yGarnPGtQ@mail.gmail.com>
@ 2021-12-21  5:43     ` Andy Shevchenko
  2021-12-22  2:28       ` Liam Beguin
  0 siblings, 1 reply; 23+ messages in thread
From: Andy Shevchenko @ 2021-12-21  5:43 UTC (permalink / raw)
  To: Liam Beguin
  Cc: peda, jic23, lars, linux-kernel, linux-iio, devicetree, robh+dt

On Tue, Dec 21, 2021 at 7:20 AM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Monday, December 20, 2021, Liam Beguin <liambeguin@gmail.com> wrote:

...

>> +               tmp = *val * 1000000000LL;
>
> I see this is the original code, but perhaps use proper SI multipliers here and there?

I mean in a separate change.

>> +               do_div(tmp, 1000000000LL);

-- 
With Best Regards,
Andy Shevchenko

^ permalink raw reply	[flat|nested] 23+ messages in thread

* Re: [PATCH v10 10/14] iio: test: add basic tests for the iio-rescale driver
  2021-12-19 22:39 ` [PATCH v10 10/14] iio: test: add basic tests for the iio-rescale driver Liam Beguin
@ 2021-12-21  7:09   ` kernel test robot
  2021-12-21  8:03   ` kernel test robot
  1 sibling, 0 replies; 23+ messages in thread
From: kernel test robot @ 2021-12-21  7:09 UTC (permalink / raw)
  To: Liam Beguin, peda, jic23, lars
  Cc: kbuild-all, linux-kernel, linux-iio, devicetree, robh+dt

Hi Liam,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on 2b6bff0b122785f09cfbdc34b1aa9edceea6e4c1]

url:    https://github.com/0day-ci/linux/commits/Liam-Beguin/iio-afe-add-temperature-rescaling-support/20211220-064048
base:   2b6bff0b122785f09cfbdc34b1aa9edceea6e4c1
config: ia64-buildonly-randconfig-r004-20211221 (https://download.01.org/0day-ci/archive/20211221/202112211453.3XBOHbkh-lkp@intel.com/config)
compiler: ia64-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/833188fad2d37f1e40f56eb7286d6dd2e1a2ced5
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Liam-Beguin/iio-afe-add-temperature-rescaling-support/20211220-064048
        git checkout 833188fad2d37f1e40f56eb7286d6dd2e1a2ced5
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=ia64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_set_suspend':
   (.text+0x732): undefined reference to `fb_set_suspend'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_resume_worker':
   drm_fb_helper.c:(.text+0x792): undefined reference to `fb_set_suspend'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_unregister_fbi':
   (.text+0x8f2): undefined reference to `unregister_framebuffer'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_fini':
   (.text+0x9c2): undefined reference to `fb_dealloc_cmap'
   ia64-linux-ld: (.text+0x9d2): undefined reference to `framebuffer_release'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_sys_read':
   (.text+0xba2): undefined reference to `fb_sys_read'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_alloc_fbi':
   (.text+0x2c82): undefined reference to `framebuffer_alloc'
   ia64-linux-ld: (.text+0x2cc2): undefined reference to `fb_alloc_cmap'
   ia64-linux-ld: (.text+0x2d52): undefined reference to `fb_dealloc_cmap'
   ia64-linux-ld: (.text+0x2d72): undefined reference to `framebuffer_release'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_generic_probe':
   drm_fb_helper.c:(.text+0x3072): undefined reference to `fb_deferred_io_init'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `__drm_fb_helper_initial_config_and_unlock':
   drm_fb_helper.c:(.text+0x3302): undefined reference to `register_framebuffer'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_set_suspend_unlocked':
   (.text+0x4842): undefined reference to `fb_set_suspend'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_sys_write':
   (.text+0x5a82): undefined reference to `fb_sys_write'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_sys_fillrect':
   (.text+0x5b22): undefined reference to `sys_fillrect'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_sys_copyarea':
   (.text+0x5bc2): undefined reference to `sys_copyarea'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_sys_imageblit':
   (.text+0x5c62): undefined reference to `sys_imageblit'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_cfb_fillrect':
   (.text+0x5d02): undefined reference to `cfb_fillrect'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_cfb_copyarea':
   (.text+0x5da2): undefined reference to `cfb_copyarea'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_cfb_imageblit':
   (.text+0x5e42): undefined reference to `cfb_imageblit'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fbdev_fb_imageblit':
   drm_fb_helper.c:(.text+0x5f12): undefined reference to `cfb_imageblit'
   ia64-linux-ld: drm_fb_helper.c:(.text+0x5f32): undefined reference to `sys_imageblit'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fbdev_fb_copyarea':
   drm_fb_helper.c:(.text+0x5ff2): undefined reference to `cfb_copyarea'
   ia64-linux-ld: drm_fb_helper.c:(.text+0x6012): undefined reference to `sys_copyarea'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fbdev_fb_fillrect':
   drm_fb_helper.c:(.text+0x60d2): undefined reference to `cfb_fillrect'
   ia64-linux-ld: drm_fb_helper.c:(.text+0x60f2): undefined reference to `sys_fillrect'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fbdev_cleanup':
   drm_fb_helper.c:(.text+0x6212): undefined reference to `fb_deferred_io_cleanup'
   ia64-linux-ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fbdev_client_unregister':
   drm_fb_helper.c:(.text+0x6402): undefined reference to `unregister_framebuffer'
   ia64-linux-ld: drivers/iio/test/iio-test-rescale.o: in function `iio_rescale_test_offset':
   iio-test-rescale.c:(.text+0x52): undefined reference to `kunit_kmalloc_array'
>> ia64-linux-ld: iio-test-rescale.c:(.text+0x1a0): undefined reference to `kunit_binary_assert_format'
>> ia64-linux-ld: iio-test-rescale.c:(.text+0x252): undefined reference to `kunit_do_assertion'
>> ia64-linux-ld: iio-test-rescale.c:(.text+0x280): undefined reference to `kunit_binary_str_assert_format'
   ia64-linux-ld: iio-test-rescale.c:(.text+0x342): undefined reference to `kunit_do_assertion'
   ia64-linux-ld: drivers/iio/test/iio-test-rescale.o: in function `iio_rescale_test_scale':
>> iio-test-rescale.c:(.text+0x570): undefined reference to `kunit_binary_assert_format'
>> ia64-linux-ld: iio-test-rescale.c:(.text+0x5b2): undefined reference to `kunit_kmalloc_array'
   ia64-linux-ld: iio-test-rescale.c:(.text+0x792): undefined reference to `kunit_do_assertion'
   ia64-linux-ld: iio-test-rescale.c:(.text+0xac2): undefined reference to `kunit_do_assertion'
   ia64-linux-ld: iio-test-rescale.c:(.text+0xb72): undefined reference to `kunit_do_assertion'

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

^ permalink raw reply	[flat|nested] 23+ messages in thread

* Re: [PATCH v10 10/14] iio: test: add basic tests for the iio-rescale driver
  2021-12-19 22:39 ` [PATCH v10 10/14] iio: test: add basic tests for the iio-rescale driver Liam Beguin
  2021-12-21  7:09   ` kernel test robot
@ 2021-12-21  8:03   ` kernel test robot
  1 sibling, 0 replies; 23+ messages in thread
From: kernel test robot @ 2021-12-21  8:03 UTC (permalink / raw)
  To: Liam Beguin, peda, jic23, lars
  Cc: kbuild-all, linux-kernel, linux-iio, devicetree, robh+dt

Hi Liam,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on 2b6bff0b122785f09cfbdc34b1aa9edceea6e4c1]

url:    https://github.com/0day-ci/linux/commits/Liam-Beguin/iio-afe-add-temperature-rescaling-support/20211220-064048
base:   2b6bff0b122785f09cfbdc34b1aa9edceea6e4c1
config: mips-randconfig-r026-20211220 (https://download.01.org/0day-ci/archive/20211221/202112211530.JHHCLDOr-lkp@intel.com/config)
compiler: mipsel-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/833188fad2d37f1e40f56eb7286d6dd2e1a2ced5
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Liam-Beguin/iio-afe-add-temperature-rescaling-support/20211220-064048
        git checkout 833188fad2d37f1e40f56eb7286d6dd2e1a2ced5
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=mips SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   mipsel-linux-ld: drivers/iio/test/iio-test-rescale.o: in function `iio_rescale_test_offset':
>> iio-test-rescale.c:(.text+0x48): undefined reference to `kunit_kmalloc_array'
>> mipsel-linux-ld: iio-test-rescale.c:(.text+0xc4): undefined reference to `kunit_binary_assert_format'
   mipsel-linux-ld: iio-test-rescale.c:(.text+0xc8): undefined reference to `kunit_binary_assert_format'
>> mipsel-linux-ld: iio-test-rescale.c:(.text+0x13c): undefined reference to `kunit_do_assertion'
>> mipsel-linux-ld: iio-test-rescale.c:(.text+0x15c): undefined reference to `kunit_binary_str_assert_format'
   mipsel-linux-ld: iio-test-rescale.c:(.text+0x160): undefined reference to `kunit_binary_str_assert_format'
   mipsel-linux-ld: iio-test-rescale.c:(.text+0x1b0): undefined reference to `kunit_do_assertion'
   mipsel-linux-ld: drivers/iio/test/iio-test-rescale.o: in function `iio_rescale_test_scale':
   iio-test-rescale.c:(.text+0x40c): undefined reference to `kunit_kmalloc_array'
   mipsel-linux-ld: iio-test-rescale.c:(.text+0x490): undefined reference to `kunit_binary_assert_format'
   mipsel-linux-ld: iio-test-rescale.c:(.text+0x4c0): undefined reference to `kunit_binary_assert_format'
   mipsel-linux-ld: iio-test-rescale.c:(.text+0x4f0): undefined reference to `kunit_do_assertion'
   mipsel-linux-ld: iio-test-rescale.c:(.text+0x6a4): undefined reference to `kunit_do_assertion'
   mipsel-linux-ld: iio-test-rescale.c:(.text+0x718): undefined reference to `kunit_do_assertion'

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

^ permalink raw reply	[flat|nested] 23+ messages in thread

* Re: [PATCH v10 03/14] iio: inkern: make a best effort on offset calculation
  2021-12-21  5:42   ` Andy Shevchenko
@ 2021-12-21 17:50     ` Liam Beguin
  0 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-21 17:50 UTC (permalink / raw)
  To: Andy Shevchenko
  Cc: Peter Rosin, Jonathan Cameron, Lars-Peter Clausen,
	Linux Kernel Mailing List, linux-iio, devicetree, Rob Herring

Hi Andy,

On Tue, Dec 21, 2021 at 07:42:31AM +0200, Andy Shevchenko wrote:
> On Mon, Dec 20, 2021 at 11:17 AM Liam Beguin <liambeguin@gmail.com> wrote:
> >
> > 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.
> 
> ...
> 
> > +                       offset_val /= (1 << offset_val2);
> 
> Besides potentially being problematic (if arg is 31 for the left
> shift) why not simply
> 
> _val >>= _val2;

That is safer, and more elegant! I'll update.

Thanks,
Liam

> --
> With Best Regards,
> Andy Shevchenko

^ permalink raw reply	[flat|nested] 23+ messages in thread

* Re: [PATCH v10 04/14] iio: afe: rescale: expose scale processing function
  2021-12-21  5:43     ` Andy Shevchenko
@ 2021-12-22  2:28       ` Liam Beguin
  0 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-22  2:28 UTC (permalink / raw)
  To: Andy Shevchenko
  Cc: peda, jic23, lars, linux-kernel, linux-iio, devicetree, robh+dt

Hi Andy,

On Tue, Dec 21, 2021 at 07:43:52AM +0200, Andy Shevchenko wrote:
> On Tue, Dec 21, 2021 at 7:20 AM Andy Shevchenko
> <andy.shevchenko@gmail.com> wrote:
> > On Monday, December 20, 2021, Liam Beguin <liambeguin@gmail.com> wrote:
> 
> ...
> 
> >> +               tmp = *val * 1000000000LL;
> >
> > I see this is the original code, but perhaps use proper SI multipliers here and there?
> 
> I mean in a separate change.

Will do!

I'll add a separate patch to convert existing multipliers, and will
fixup the ones I'm adding.

Cheers,
Liam

> >> +               do_div(tmp, 1000000000LL);
> 
> -- 
> With Best Regards,
> Andy Shevchenko

^ permalink raw reply	[flat|nested] 23+ messages in thread

* Re: [PATCH v10 00/14] iio: afe: add temperature rescaling support
  2021-12-20 21:37 ` [PATCH v10 00/14] iio: afe: add temperature rescaling support Peter Rosin
@ 2021-12-22  3:29   ` Liam Beguin
  0 siblings, 0 replies; 23+ messages in thread
From: Liam Beguin @ 2021-12-22  3:29 UTC (permalink / raw)
  To: Peter Rosin; +Cc: jic23, lars, linux-kernel, linux-iio, devicetree, robh+dt

Hi Peter,

On Mon, Dec 20, 2021 at 10:37:26PM +0100, Peter Rosin wrote:
> Hi!
> 
> On 2021-12-19 23:39, Liam Beguin wrote:
> > Hi Jonathan, Peter,
> > 
> > I left out IIO_VAL_INT overflows for now, so that I can focus on getting
> > the rest of these changes pulled in, but I don't mind adding a patch for
> > that later on.
> > 
> > This series focuses on adding temperature rescaling support to the IIO
> > Analog Front End (AFE) driver.
> > 
> > The first few patches address minor bugs in IIO inkernel functions, and
> > prepare the AFE driver for the additional features.
> > 
> > The main changes to the AFE driver include an initial Kunit test suite,
> > support for IIO_VAL_INT_PLUS_{NANO,MICRO} scales, and support for RTDs
> > and temperature transducer sensors.
> > 
> > Thanks for your time,
> > Liam
> 
> And thanks for your time and persistence!
> 
> This now looks in good order, so for the whole series:
> 
> Reviewed-by: Peter Rosin <peda@axentia.se>

Thanks for your time (and patience ;-) on this series!

Cheers,
Liam

> Cheers,
> Peter

^ permalink raw reply	[flat|nested] 23+ messages in thread

end of thread, other threads:[~2021-12-22  3:29 UTC | newest]

Thread overview: 23+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-12-19 22:39 [PATCH v10 00/14] iio: afe: add temperature rescaling support Liam Beguin
2021-12-19 22:39 ` [PATCH v10 01/14] iio: inkern: apply consumer scale on IIO_VAL_INT cases Liam Beguin
2021-12-19 22:39 ` [PATCH v10 02/14] iio: inkern: apply consumer scale when no channel scale is available Liam Beguin
2021-12-19 22:39 ` [PATCH v10 03/14] iio: inkern: make a best effort on offset calculation Liam Beguin
2021-12-21  5:42   ` Andy Shevchenko
2021-12-21 17:50     ` Liam Beguin
2021-12-19 22:39 ` [PATCH v10 04/14] iio: afe: rescale: expose scale processing function Liam Beguin
     [not found]   ` <CAHp75VdfPf6FMvkGqhhQg5e5XE1cgE-K8seobe5n0yGarnPGtQ@mail.gmail.com>
2021-12-21  5:43     ` Andy Shevchenko
2021-12-22  2:28       ` Liam Beguin
2021-12-19 22:39 ` [PATCH v10 05/14] iio: afe: rescale: add INT_PLUS_{MICRO,NANO} support Liam Beguin
2021-12-19 22:39 ` [PATCH v10 06/14] iio: afe: rescale: add offset support Liam Beguin
2021-12-19 22:39 ` [PATCH v10 07/14] iio: afe: rescale: use s64 for temporary scale calculations Liam Beguin
2021-12-19 22:39 ` [PATCH v10 08/14] iio: afe: rescale: fix accuracy for small fractional scales Liam Beguin
2021-12-19 22:39 ` [PATCH v10 09/14] iio: afe: rescale: reduce risk of integer overflow Liam Beguin
2021-12-19 22:39 ` [PATCH v10 10/14] iio: test: add basic tests for the iio-rescale driver Liam Beguin
2021-12-21  7:09   ` kernel test robot
2021-12-21  8:03   ` kernel test robot
2021-12-19 22:39 ` [PATCH v10 11/14] iio: afe: rescale: add RTD temperature sensor support Liam Beguin
2021-12-19 22:39 ` [PATCH v10 12/14] iio: afe: rescale: add temperature transducers Liam Beguin
2021-12-19 22:39 ` [PATCH v10 13/14] dt-bindings: iio: afe: add bindings for temperature-sense-rtd Liam Beguin
2021-12-19 22:39 ` [PATCH v10 14/14] dt-bindings: iio: afe: add bindings for temperature transducers Liam Beguin
2021-12-20 21:37 ` [PATCH v10 00/14] iio: afe: add temperature rescaling support Peter Rosin
2021-12-22  3:29   ` Liam Beguin

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