[PATCH v6 00/11] iio: adc: hx711: add HX710B support

[PATCH v6 00/11] iio: adc: hx711: add HX710B support

[Piyush Patle]

Add support for the AVIA HX710B ADC, a HX711-compatible converter with
the same GPIO interface but a different channel-selection model and a
fixed gain of 128.

Compared to v5, this series is unchanged functionally and only folds in
the remaining review nits:

- keep the per-variant probe local declarations in reversed xmas tree
  order
- add a preparatory split-assignment patch before the loop-iterator
  cleanup, then keep the loop indices signed to match trailing_pulses
- replace the 24-bit read loop bound with a named constant while
  touching the same code
- keep the driver wording aligned on "weigh sensor modules"
- rename fixed_gain to has_fixed_gain and drop the channel_set cast

The DT binding split from v5 is kept as-is:

- cleanup of the existing HX711 binding text
- HX711-only VSUP documentation
- HX711-only RATE GPIO documentation
- HX710B binding addition

Tested on PocketBeagle2 with an HX710B breakout module. The device
probed successfully, all three channels returned stable raw readings,
and alternating reads confirmed channel switching between the
differential input and the DVDD-AVDD supply monitor path.

Build-tested with:
- make -s W=1 drivers/iio/adc/hx711.o
- make -s dt_binding_check \
  DT_SCHEMA_FILES=Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
- pahole -C hx711_chip_info drivers/iio/adc/hx711.o

pahole reports hx711_chip_info as 40 bytes with no internal holes. The
remaining 7 bytes are tail padding from 8-byte pointer alignment.

Changes in v6:
- Fold the remaining review nits into the original 11-patch series
  rather than adding follow-up fixes.
- Keep hx711_probe() local declarations in reversed xmas tree order in
  the hx711_chip_info patch.
- Add a preparatory split-assignment patch before the loop-iterator
  cleanup and keep the iterator types signed to match trailing_pulses.
- Replace the 24-bit hx711_read() loop bound with HX711_DATA_BITS in
  the loop-iterator patch.
- Keep the driver header wording as "weigh sensor modules".
- Rename fixed_gain to has_fixed_gain and make channel_set signed so
  the HX710B channel comparison no longer needs a cast.

Piyush Patle (11):
  dt-bindings: iio: adc: hx711: clean up existing binding text
  dt-bindings: iio: adc: hx711: add VSUP supply property
  dt-bindings: iio: adc: hx711: add RATE GPIO property
  dt-bindings: iio: adc: hx711: add HX710B support
  iio: adc: hx711: move scale computation to per-device storage
  iio: adc: hx711: introduce hx711_chip_info structure
  iio: adc: hx711: pass trailing pulse count into hx711_read
  iio: adc: hx711: split variable assignments in hx711_read and
    hx711_reset
  iio: adc: hx711: localize loop iterators in hx711_read
  iio: adc: hx711: pass iio_chan_spec to hx711_reset_read
  iio: adc: hx711: add support for HX710B

 .../bindings/iio/adc/avia-hx711.yaml          |  77 ++++-
 drivers/iio/adc/Kconfig                       |   8 +-
 drivers/iio/adc/hx711.c                       | 299 ++++++++++++++----
 3 files changed, 308 insertions(+), 76 deletions(-)

-- 
2.43.0

[PATCH v6 01/11] dt-bindings: iio: adc: hx711: clean up existing binding text

[Piyush Patle]

Rewrite the binding description and property text so it describes the
existing HX711 hardware behavior directly instead of documenting old
driver implementation details.

Also clarify that clock-frequency controls the SCK bit-bang timing.

No functional change.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
 .../bindings/iio/adc/avia-hx711.yaml          | 25 ++++++++-----------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
index 9c57eb13f892..1ea60dff98d5 100644
--- a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
@@ -10,14 +10,9 @@ maintainers:
   - Andreas Klinger <ak@it-klinger.de>
 
 description: |
-  Bit-banging driver using two GPIOs:
-  - sck-gpio gives a clock to the sensor with 24 cycles for data retrieval
-    and up to 3 cycles for selection of the input channel and gain for the
-    next measurement
-  - dout-gpio is the sensor data the sensor responds to the clock
-
-  Specifications about the driver can be found at:
-  http://www.aviaic.com/ENProducts.aspx
+  The HX711 is a 24-bit ADC with selectable gain (32/64/128) and two
+  differential input channels. Channel A supports gain 64 and 128;
+  channel B supports gain 32.
 
 properties:
   compatible:
@@ -26,23 +21,23 @@ properties:
 
   sck-gpios:
     description:
-      Definition of the GPIO for the clock (output). In the datasheet it is
-      named PD_SCK
+      GPIO for the clock output (PD_SCK in the datasheet).
     maxItems: 1
 
   dout-gpios:
     description:
-      Definition of the GPIO for the data-out sent by the sensor in
-      response to the clock (input).
-      See Documentation/devicetree/bindings/gpio/gpio.txt for information
-      on how to specify a consumer gpio.
+      GPIO for the data output from the sensor (DOUT in the datasheet).
     maxItems: 1
 
   avdd-supply:
     description:
-      Definition of the regulator used as analog supply
+      Analog supply voltage (AVDD).
 
   clock-frequency:
+    description:
+      Controls the SCK bit-bang timing. The value is used to derive the
+      delay between SCK edges; keep the SCK high time below 60 us to
+      avoid triggering chip power-down mode.
     minimum: 20000
     maximum: 2500000
     default: 400000
-- 
2.43.0

[PATCH v6 02/11] dt-bindings: iio: adc: hx711: add VSUP supply property

[Piyush Patle]

Document the optional VSUP supply used by the HX711 on-chip regulator.

Keep this separate from the HX710B support so the existing HX711
binding extension stands on its own.

No functional change for existing users.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
 Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
index 1ea60dff98d5..a8eaa1f18de5 100644
--- a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
@@ -33,6 +33,10 @@ properties:
     description:
       Analog supply voltage (AVDD).
 
+  vsup-supply:
+    description:
+      Supply voltage for the on-chip regulator (VSUP).
+
   clock-frequency:
     description:
       Controls the SCK bit-bang timing. The value is used to derive the
-- 
2.43.0

[PATCH v6 03/11] dt-bindings: iio: adc: hx711: add RATE GPIO property

[Piyush Patle]

Document the optional RATE pin GPIO used to select the HX711 output
data rate.

Update the example to show the property in use.

No functional change for existing users.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
 Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
index a8eaa1f18de5..9134bbe41379 100644
--- a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
@@ -37,6 +37,13 @@ properties:
     description:
       Supply voltage for the on-chip regulator (VSUP).
 
+  rate-gpios:
+    description:
+      GPIO connected to the RATE pin. When driven low the output data
+      rate is 10 SPS; when driven high it is 80 SPS. If omitted the
+      RATE pin state is determined by the board wiring.
+    maxItems: 1
+
   clock-frequency:
     description:
       Controls the SCK bit-bang timing. The value is used to derive the
@@ -61,6 +68,7 @@ examples:
         compatible = "avia,hx711";
         sck-gpios = <&gpio3 10 GPIO_ACTIVE_HIGH>;
         dout-gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>;
+        rate-gpios = <&gpio0 9 GPIO_ACTIVE_HIGH>;
         avdd-supply = <&avdd>;
         clock-frequency = <100000>;
     };
-- 
2.43.0

[PATCH v6 04/11] dt-bindings: iio: adc: hx711: add HX710B support

[Piyush Patle]

Add the avia,hx710b compatible and document the HX710B-specific
DVDD and VREF supplies.

Add constraints that forbid HX711-only properties on HX710B nodes and
require vref-supply for HX710B, then add a separate HX710B example.

Keep the existing HX711-only binding extensions in earlier patches so
this change is limited to the new variant.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
 .../bindings/iio/adc/avia-hx711.yaml          | 42 ++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
index 9134bbe41379..b2b5c7bdf05e 100644
--- a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
@@ -4,7 +4,7 @@
 $id: http://devicetree.org/schemas/iio/adc/avia-hx711.yaml#
 $schema: http://devicetree.org/meta-schemas/core.yaml#
 
-title: AVIA HX711 ADC chip for weight cells
+title: AVIA HX711 and HX710B ADCs
 
 maintainers:
   - Andreas Klinger <ak@it-klinger.de>
@@ -14,9 +14,14 @@ description: |
   differential input channels. Channel A supports gain 64 and 128;
   channel B supports gain 32.
 
+  The HX710B is a 24-bit ADC with fixed gain of 128. One input measures
+  the differential voltage between the two input pins; a second measures
+  the DVDD-AVDD supply voltage difference for battery level detection.
+
 properties:
   compatible:
     enum:
+      - avia,hx710b
       - avia,hx711
 
   sck-gpios:
@@ -44,6 +49,17 @@ properties:
       RATE pin state is determined by the board wiring.
     maxItems: 1
 
+  dvdd-supply:
+    description:
+      Digital supply voltage (DVDD). For the HX710B, DVDD must be
+      greater than or equal to AVDD. When DVDD is a battery rail and
+      AVDD is a regulated supply, one channel monitors the DVDD-AVDD
+      difference for battery level detection.
+
+  vref-supply:
+    description:
+      Reference voltage input (VREF).
+
   clock-frequency:
     description:
       Controls the SCK bit-bang timing. The value is used to derive the
@@ -53,6 +69,21 @@ properties:
     maximum: 2500000
     default: 400000
 
+allOf:
+  - if:
+      properties:
+        compatible:
+          const: avia,hx710b
+    then:
+      properties:
+        vsup-supply: false
+        rate-gpios: false
+      required:
+        - vref-supply
+    else:
+      properties:
+        vref-supply: false
+
 required:
   - compatible
   - sck-gpios
@@ -72,3 +103,12 @@ examples:
         avdd-supply = <&avdd>;
         clock-frequency = <100000>;
     };
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    weight {
+        compatible = "avia,hx710b";
+        sck-gpios = <&gpio3 10 GPIO_ACTIVE_HIGH>;
+        dout-gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>;
+        avdd-supply = <&avdd>;
+        vref-supply = <&vref>;
+    };
-- 
2.43.0

[PATCH v6 05/11] iio: adc: hx711: move scale computation to per-device storage

[Piyush Patle]

The gain-to-scale table is global today, so probe-time scale updates for
one device overwrite the values used by any earlier device instance.

Fix this by making the gain table const and storing the computed scale
values per device in hx711_data.

No functional change for single-sensor configurations.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
 drivers/iio/adc/hx711.c | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index 1db8b68a8f64..8485e18c949d 100644
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -28,22 +28,20 @@
 struct hx711_gain_to_scale {
 	int			gain;
 	int			gain_pulse;
-	int			scale;
 	int			channel;
 };
 
 /*
  * .scale depends on AVDD which in turn is known as soon as the regulator
- * is available
- * therefore we set .scale in hx711_probe()
+ * is available; it is stored per device in hx711_data.gain_scale[]
  *
  * channel A in documentation is channel 0 in source code
  * channel B in documentation is channel 1 in source code
  */
-static struct hx711_gain_to_scale hx711_gain_to_scale[HX711_GAIN_MAX] = {
-	{ 128, 1, 0, 0 },
-	{  32, 2, 0, 1 },
-	{  64, 3, 0, 0 }
+static const struct hx711_gain_to_scale hx711_gain_to_scale[HX711_GAIN_MAX] = {
+	{ 128, 1, 0, },
+	{  32, 2, 1, },
+	{  64, 3, 0, },
 };
 
 static int hx711_get_gain_to_pulse(int gain)
@@ -56,22 +54,22 @@ static int hx711_get_gain_to_pulse(int gain)
 	return 1;
 }
 
-static int hx711_get_gain_to_scale(int gain)
+static int hx711_get_gain_to_scale(const int *gain_scale, int gain)
 {
 	int i;
 
 	for (i = 0; i < HX711_GAIN_MAX; i++)
 		if (hx711_gain_to_scale[i].gain == gain)
-			return hx711_gain_to_scale[i].scale;
+			return gain_scale[i];
 	return 0;
 }
 
-static int hx711_get_scale_to_gain(int scale)
+static int hx711_get_scale_to_gain(const int *gain_scale, int scale)
 {
 	int i;
 
 	for (i = 0; i < HX711_GAIN_MAX; i++)
-		if (hx711_gain_to_scale[i].scale == scale)
+		if (gain_scale[i] == scale)
 			return hx711_gain_to_scale[i].gain;
 	return -EINVAL;
 }
@@ -82,6 +80,7 @@ struct hx711_data {
 	struct gpio_desc	*gpiod_dout;
 	int			gain_set;	/* gain set on device */
 	int			gain_chan_a;	/* gain for channel A */
+	int			gain_scale[HX711_GAIN_MAX];
 	struct mutex		lock;
 	/*
 	 * triggered buffer
@@ -290,7 +289,8 @@ static int hx711_read_raw(struct iio_dev *indio_dev,
 		*val = 0;
 		mutex_lock(&hx711_data->lock);
 
-		*val2 = hx711_get_gain_to_scale(hx711_data->gain_set);
+		*val2 = hx711_get_gain_to_scale(hx711_data->gain_scale,
+						hx711_data->gain_set);
 
 		mutex_unlock(&hx711_data->lock);
 
@@ -321,7 +321,7 @@ static int hx711_write_raw(struct iio_dev *indio_dev,
 
 		mutex_lock(&hx711_data->lock);
 
-		gain = hx711_get_scale_to_gain(val2);
+		gain = hx711_get_scale_to_gain(hx711_data->gain_scale, val2);
 		if (gain < 0) {
 			mutex_unlock(&hx711_data->lock);
 			return gain;
@@ -386,6 +386,7 @@ static ssize_t hx711_scale_available_show(struct device *dev,
 				struct device_attribute *attr,
 				char *buf)
 {
+	struct hx711_data *hx711_data = iio_priv(dev_to_iio_dev(dev));
 	struct iio_dev_attr *iio_attr = to_iio_dev_attr(attr);
 	int channel = iio_attr->address;
 	int i, len = 0;
@@ -393,7 +394,7 @@ static ssize_t hx711_scale_available_show(struct device *dev,
 	for (i = 0; i < HX711_GAIN_MAX; i++)
 		if (hx711_gain_to_scale[i].channel == channel)
 			len += sprintf(buf + len, "0.%09d ",
-					hx711_gain_to_scale[i].scale);
+					hx711_data->gain_scale[i]);
 
 	len += sprintf(buf + len, "\n");
 
@@ -511,7 +512,7 @@ static int hx711_probe(struct platform_device *pdev)
 	ret *= 100;
 
 	for (i = 0; i < HX711_GAIN_MAX; i++)
-		hx711_gain_to_scale[i].scale =
+		hx711_data->gain_scale[i] =
 			ret / hx711_gain_to_scale[i].gain / 1678;
 
 	hx711_data->gain_set = 128;
@@ -574,4 +575,3 @@ MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
 MODULE_DESCRIPTION("HX711 bitbanging driver - ADC for weight cells");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:hx711-gpio");
-
-- 
2.43.0

[PATCH v6 06/11] iio: adc: hx711: introduce hx711_chip_info structure

[Piyush Patle]

Add a per-variant static configuration structure and populate the IIO
device fields from it at probe time.

This is a preparatory change for adding support for more HX711-compatible
hardware variants without duplicating the probe-time setup.

No functional change for existing HX711 users.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
 drivers/iio/adc/hx711.c | 41 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 36 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index 8485e18c949d..534b73fcaab8 100644
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -4,6 +4,8 @@
  *
  * Copyright (c) 2016 Andreas Klinger <ak@it-klinger.de>
  */
+#include <linux/array_size.h>
+#include <linux/dev_printk.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -74,6 +76,20 @@ static int hx711_get_scale_to_gain(const int *gain_scale, int scale)
 	return -EINVAL;
 }
 
+/**
+ * struct hx711_chip_info - per-variant static configuration
+ * @name: IIO device name
+ * @channels: channel specification array
+ * @iio_info: IIO info ops for this variant
+ * @num_channels: number of entries in @channels
+ */
+struct hx711_chip_info {
+	const char			*name;
+	const struct iio_chan_spec	*channels;
+	const struct iio_info		*iio_info;
+	unsigned int			num_channels;
+};
+
 struct hx711_data {
 	struct device		*dev;
 	struct gpio_desc	*gpiod_pd_sck;
@@ -81,6 +97,7 @@ struct hx711_data {
 	int			gain_set;	/* gain set on device */
 	int			gain_chan_a;	/* gain for channel A */
 	int			gain_scale[HX711_GAIN_MAX];
+	const struct hx711_chip_info	*chip_info;
 	struct mutex		lock;
 	/*
 	 * triggered buffer
@@ -456,8 +473,16 @@ static const struct iio_chan_spec hx711_chan_spec[] = {
 	IIO_CHAN_SOFT_TIMESTAMP(2),
 };
 
+static const struct hx711_chip_info hx711_chip = {
+	.name		= "hx711",
+	.channels	= hx711_chan_spec,
+	.iio_info	= &hx711_iio_info,
+	.num_channels	= ARRAY_SIZE(hx711_chan_spec),
+};
+
 static int hx711_probe(struct platform_device *pdev)
 {
+	const struct hx711_chip_info *chip_info;
 	struct device *dev = &pdev->dev;
 	struct hx711_data *hx711_data;
 	struct iio_dev *indio_dev;
@@ -473,6 +498,12 @@ static int hx711_probe(struct platform_device *pdev)
 
 	mutex_init(&hx711_data->lock);
 
+	chip_info = device_get_match_data(dev);
+	if (!chip_info)
+		return dev_err_probe(dev, -ENODEV, "missing driver data\n");
+
+	hx711_data->chip_info = chip_info;
+
 	/*
 	 * PD_SCK stands for power down and serial clock input of HX711
 	 * in the driver it is an output
@@ -534,11 +565,11 @@ static int hx711_probe(struct platform_device *pdev)
 	hx711_data->data_ready_delay_ns =
 				1000000000 / hx711_data->clock_frequency;
 
-	indio_dev->name = "hx711";
-	indio_dev->info = &hx711_iio_info;
+	indio_dev->name = chip_info->name;
+	indio_dev->info = chip_info->iio_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
-	indio_dev->channels = hx711_chan_spec;
-	indio_dev->num_channels = ARRAY_SIZE(hx711_chan_spec);
+	indio_dev->channels = chip_info->channels;
+	indio_dev->num_channels = chip_info->num_channels;
 
 	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
 					      iio_pollfunc_store_time,
@@ -555,7 +586,7 @@ static int hx711_probe(struct platform_device *pdev)
 }
 
 static const struct of_device_id of_hx711_match[] = {
-	{ .compatible = "avia,hx711", },
+	{ .compatible = "avia,hx711", .data = &hx711_chip },
 	{ }
 };
 
-- 
2.43.0

[PATCH v6 07/11] iio: adc: hx711: pass trailing pulse count into hx711_read

[Piyush Patle]

Move the trailing-pulse selection out of hx711_read() and into its
callers.

This is a preparatory change so later variant-specific code can pass the
per-channel pulse count without adding a separate read path.

No functional change.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
 drivers/iio/adc/hx711.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index 534b73fcaab8..637114635867 100644
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -155,7 +155,7 @@ static int hx711_cycle(struct hx711_data *hx711_data)
 	return gpiod_get_value(hx711_data->gpiod_dout);
 }
 
-static int hx711_read(struct hx711_data *hx711_data)
+static int hx711_read(struct hx711_data *hx711_data, int trailing_pulses)
 {
 	int i, ret;
 	int value = 0;
@@ -174,7 +174,7 @@ static int hx711_read(struct hx711_data *hx711_data)
 
 	value ^= 0x800000;
 
-	for (i = 0; i < hx711_get_gain_to_pulse(hx711_data->gain_set); i++)
+	for (i = 0; i < trailing_pulses; i++)
 		hx711_cycle(hx711_data);
 
 	return value;
@@ -237,7 +237,8 @@ static int hx711_set_gain_for_channel(struct hx711_data *hx711_data, int chan)
 		if (hx711_data->gain_set == 32) {
 			hx711_data->gain_set = hx711_data->gain_chan_a;
 
-			ret = hx711_read(hx711_data);
+			ret = hx711_read(hx711_data,
+					 hx711_get_gain_to_pulse(hx711_data->gain_set));
 			if (ret < 0)
 				return ret;
 
@@ -249,7 +250,8 @@ static int hx711_set_gain_for_channel(struct hx711_data *hx711_data, int chan)
 		if (hx711_data->gain_set != 32) {
 			hx711_data->gain_set = 32;
 
-			ret = hx711_read(hx711_data);
+			ret = hx711_read(hx711_data,
+					 hx711_get_gain_to_pulse(hx711_data->gain_set));
 			if (ret < 0)
 				return ret;
 
@@ -264,8 +266,8 @@ static int hx711_set_gain_for_channel(struct hx711_data *hx711_data, int chan)
 
 static int hx711_reset_read(struct hx711_data *hx711_data, int chan)
 {
+	int trailing_pulses;
 	int ret;
-	int val;
 
 	/*
 	 * hx711_reset() must be called from here
@@ -280,9 +282,8 @@ static int hx711_reset_read(struct hx711_data *hx711_data, int chan)
 	if (ret < 0)
 		return ret;
 
-	val = hx711_read(hx711_data);
-
-	return val;
+	trailing_pulses = hx711_get_gain_to_pulse(hx711_data->gain_set);
+	return hx711_read(hx711_data, trailing_pulses);
 }
 
 static int hx711_read_raw(struct iio_dev *indio_dev,
@@ -349,7 +350,8 @@ static int hx711_write_raw(struct iio_dev *indio_dev,
 			if (gain != 32)
 				hx711_data->gain_chan_a = gain;
 
-			ret = hx711_read(hx711_data);
+			ret = hx711_read(hx711_data,
+					 hx711_get_gain_to_pulse(hx711_data->gain_set));
 			if (ret < 0) {
 				mutex_unlock(&hx711_data->lock);
 				return ret;
-- 
2.43.0

[PATCH v6 08/11] iio: adc: hx711: split variable assignments in hx711_read and hx711_reset

[Piyush Patle]

Separate the initial value assignments from the declarations in
hx711_read() and hx711_reset().

This is a small preparatory cleanup before the later loop-iterator and
variant-specific changes adjust the local variable layout in these
functions.

No functional change.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
 drivers/iio/adc/hx711.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index 637114635867..b2de8db285b2 100644
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -159,7 +159,9 @@ static int hx711_read(struct hx711_data *hx711_data, int trailing_pulses)
 {
 	int i, ret;
 	int value = 0;
-	int val = gpiod_get_value(hx711_data->gpiod_dout);
+	int val;
+
+	val = gpiod_get_value(hx711_data->gpiod_dout);
 
 	/* we double check if it's really down */
 	if (val)
@@ -204,7 +206,9 @@ static int hx711_wait_for_ready(struct hx711_data *hx711_data)
 
 static int hx711_reset(struct hx711_data *hx711_data)
 {
-	int val = hx711_wait_for_ready(hx711_data);
+	int val;
+
+	val = hx711_wait_for_ready(hx711_data);
 
 	if (val) {
 		/*
-- 
2.43.0

[PATCH v6 09/11] iio: adc: hx711: localize loop iterators in hx711_read

[Piyush Patle]

Tighten the scope of the loop variables in hx711_read() now that
trailing-pulse selection is already handled by the callers.

Also replace the 24-bit loop bound with a named constant while touching
the same code.

Suggested-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
 drivers/iio/adc/hx711.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index b2de8db285b2..98fb617ea32b 100644
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -24,6 +24,7 @@
 #include <linux/regulator/consumer.h>
 
 /* gain to pulse and scale conversion */
+#define HX711_DATA_BITS		24
 #define HX711_GAIN_MAX		3
 #define HX711_RESET_GAIN	128
 
@@ -157,9 +158,9 @@ static int hx711_cycle(struct hx711_data *hx711_data)
 
 static int hx711_read(struct hx711_data *hx711_data, int trailing_pulses)
 {
-	int i, ret;
 	int value = 0;
 	int val;
+	int ret;
 
 	val = gpiod_get_value(hx711_data->gpiod_dout);
 
@@ -167,7 +168,7 @@ static int hx711_read(struct hx711_data *hx711_data, int trailing_pulses)
 	if (val)
 		return -EIO;
 
-	for (i = 0; i < 24; i++) {
+	for (int i = 0; i < HX711_DATA_BITS; i++) {
 		value <<= 1;
 		ret = hx711_cycle(hx711_data);
 		if (ret)
@@ -176,7 +177,7 @@ static int hx711_read(struct hx711_data *hx711_data, int trailing_pulses)
 
 	value ^= 0x800000;
 
-	for (i = 0; i < trailing_pulses; i++)
+	for (int i = 0; i < trailing_pulses; i++)
 		hx711_cycle(hx711_data);
 
 	return value;
-- 
2.43.0

[PATCH v6 10/11] iio: adc: hx711: pass iio_chan_spec to hx711_reset_read

[Piyush Patle]

Change hx711_reset_read() to accept the channel descriptor directly and
update its callers accordingly.

Split the existing HX711 channel-selection work into a small helper so a
later variant-specific change can add a matching helper without growing
hx711_reset_read() further.

No functional change.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
 drivers/iio/adc/hx711.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index 98fb617ea32b..2229df17f350 100644
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -269,7 +269,22 @@ static int hx711_set_gain_for_channel(struct hx711_data *hx711_data, int chan)
 	return 0;
 }
 
-static int hx711_reset_read(struct hx711_data *hx711_data, int chan)
+static int hx711_set_hx711_channel(struct hx711_data *hx711_data,
+				   const struct iio_chan_spec *chan,
+				   int *trailing_pulses)
+{
+	int ret;
+
+	ret = hx711_set_gain_for_channel(hx711_data, chan->channel);
+	if (ret < 0)
+		return ret;
+
+	*trailing_pulses = hx711_get_gain_to_pulse(hx711_data->gain_set);
+	return 0;
+}
+
+static int hx711_reset_read(struct hx711_data *hx711_data,
+			    const struct iio_chan_spec *chan)
 {
 	int trailing_pulses;
 	int ret;
@@ -283,11 +298,10 @@ static int hx711_reset_read(struct hx711_data *hx711_data, int chan)
 		return -EIO;
 	}
 
-	ret = hx711_set_gain_for_channel(hx711_data, chan);
+	ret = hx711_set_hx711_channel(hx711_data, chan, &trailing_pulses);
 	if (ret < 0)
 		return ret;
 
-	trailing_pulses = hx711_get_gain_to_pulse(hx711_data->gain_set);
 	return hx711_read(hx711_data, trailing_pulses);
 }
 
@@ -301,7 +315,7 @@ static int hx711_read_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&hx711_data->lock);
 
-		*val = hx711_reset_read(hx711_data, chan->channel);
+		*val = hx711_reset_read(hx711_data, chan);
 
 		mutex_unlock(&hx711_data->lock);
 
@@ -391,8 +405,8 @@ static irqreturn_t hx711_trigger(int irq, void *p)
 	memset(&hx711_data->buffer, 0, sizeof(hx711_data->buffer));
 
 	iio_for_each_active_channel(indio_dev, i) {
-		hx711_data->buffer.channel[j] = hx711_reset_read(hx711_data,
-					indio_dev->channels[i].channel);
+		hx711_data->buffer.channel[j] =
+			hx711_reset_read(hx711_data, &indio_dev->channels[i]);
 		j++;
 	}
 
-- 
2.43.0

[PATCH v6 11/11] iio: adc: hx711: add support for HX710B

[Piyush Patle]

Add support for the AVIA HX710B ADC, which shares the HX711 GPIO
interface but uses trailing PD_SCK pulses to select the active mode.

Model the HX710B with variant-specific channel tables and IIO info,
track the active channel across conversions, and use the fixed gain
value when computing scale.

Also update the adjacent Kconfig text, file header, and module
description so the driver text matches the newly supported variant.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
 drivers/iio/adc/Kconfig |   8 +-
 drivers/iio/adc/hx711.c | 173 +++++++++++++++++++++++++++++++++++-----
 2 files changed, 157 insertions(+), 24 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 60038ae8dfc4..09a1b29fbd9c 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -784,13 +784,15 @@ config HI8435
 	  called hi8435.
 
 config HX711
-	tristate "AVIA HX711 ADC for weight cells"
+	tristate "AVIA HX711 and compatible ADCs"
 	depends on GPIOLIB
 	select IIO_BUFFER
 	select IIO_TRIGGERED_BUFFER
 	help
-	  If you say yes here you get support for AVIA HX711 ADC which is used
-	  for weigh cells
+	  If you say Y here you get support for the following AVIA ADCs:
+	    - HX710B
+	    - HX711
+	  which are used for bridge sensors such as weigh cells.
 
 	  This driver uses two GPIOs, one acts as the clock and controls the
 	  channel selection and gain, the other one is used for the measurement
diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index 2229df17f350..521244bd6a7b 100644
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
- * HX711: analog to digital converter for weight sensor module
+ * HX711 and compatible ADCs driver for weigh sensor modules
  *
  * Copyright (c) 2016 Andreas Klinger <ak@it-klinger.de>
  */
@@ -15,6 +15,7 @@
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/delay.h>
+#include <linux/types.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/buffer.h>
@@ -83,12 +84,16 @@ static int hx711_get_scale_to_gain(const int *gain_scale, int scale)
  * @channels: channel specification array
  * @iio_info: IIO info ops for this variant
  * @num_channels: number of entries in @channels
+ * @fixed_gain_val: fixed PGA gain (used when @has_fixed_gain is true)
+ * @has_fixed_gain: true if the variant has a fixed ADC gain
  */
 struct hx711_chip_info {
 	const char			*name;
 	const struct iio_chan_spec	*channels;
 	const struct iio_info		*iio_info;
 	unsigned int			num_channels;
+	unsigned int			fixed_gain_val;
+	bool				has_fixed_gain;
 };
 
 struct hx711_data {
@@ -98,14 +103,16 @@ struct hx711_data {
 	int			gain_set;	/* gain set on device */
 	int			gain_chan_a;	/* gain for channel A */
 	int			gain_scale[HX711_GAIN_MAX];
+	int			channel_set;	/* HX710B active channel */
 	const struct hx711_chip_info	*chip_info;
 	struct mutex		lock;
 	/*
 	 * triggered buffer
-	 * 2x32-bit channel + 64-bit naturally aligned timestamp
+	 * up to 3x32-bit channels + pad + 64-bit naturally aligned timestamp
 	 */
 	struct {
-		u32 channel[2];
+		u32 channel[3];
+		u32 pad;
 		aligned_s64 timestamp;
 	} buffer;
 	/*
@@ -207,6 +214,7 @@ static int hx711_wait_for_ready(struct hx711_data *hx711_data)
 
 static int hx711_reset(struct hx711_data *hx711_data)
 {
+	const struct hx711_chip_info *info = hx711_data->chip_info;
 	int val;
 
 	val = hx711_wait_for_ready(hx711_data);
@@ -227,8 +235,11 @@ static int hx711_reset(struct hx711_data *hx711_data)
 
 		val = hx711_wait_for_ready(hx711_data);
 
-		/* after a reset the gain is 128 */
-		hx711_data->gain_set = HX711_RESET_GAIN;
+		if (info->has_fixed_gain)
+			hx711_data->channel_set = 0;
+		else
+			/* after a reset the gain is 128 */
+			hx711_data->gain_set = HX711_RESET_GAIN;
 	}
 
 	return val;
@@ -283,9 +294,36 @@ static int hx711_set_hx711_channel(struct hx711_data *hx711_data,
 	return 0;
 }
 
+/*
+ * Switch the HX710B to the requested channel for the next conversion.
+ * chan->address holds the trailing pulse count (Table 3 in datasheet).
+ * channel_set is updated only after both reads succeed.
+ */
+static int hx711_set_hx710b_channel(struct hx711_data *hx711_data,
+				    const struct iio_chan_spec *chan)
+{
+	int ret;
+
+	if (hx711_data->channel_set == chan->channel)
+		return 0;
+
+	ret = hx711_read(hx711_data, chan->address);
+	if (ret < 0)
+		return ret;
+
+	ret = hx711_wait_for_ready(hx711_data);
+	if (ret)
+		return ret;
+
+	hx711_data->channel_set = chan->channel;
+
+	return 0;
+}
+
 static int hx711_reset_read(struct hx711_data *hx711_data,
 			    const struct iio_chan_spec *chan)
 {
+	const struct hx711_chip_info *info = hx711_data->chip_info;
 	int trailing_pulses;
 	int ret;
 
@@ -298,9 +336,16 @@ static int hx711_reset_read(struct hx711_data *hx711_data,
 		return -EIO;
 	}
 
-	ret = hx711_set_hx711_channel(hx711_data, chan, &trailing_pulses);
-	if (ret < 0)
-		return ret;
+	if (info->has_fixed_gain) {
+		ret = hx711_set_hx710b_channel(hx711_data, chan);
+		if (ret < 0)
+			return ret;
+		trailing_pulses = chan->address;
+	} else {
+		ret = hx711_set_hx711_channel(hx711_data, chan, &trailing_pulses);
+		if (ret < 0)
+			return ret;
+	}
 
 	return hx711_read(hx711_data, trailing_pulses);
 }
@@ -462,6 +507,10 @@ static const struct iio_info hx711_iio_info = {
 	.attrs			= &hx711_attribute_group,
 };
 
+static const struct iio_info hx710b_iio_info = {
+	.read_raw		= hx711_read_raw,
+};
+
 static const struct iio_chan_spec hx711_chan_spec[] = {
 	{
 		.type = IIO_VOLTAGE,
@@ -494,6 +543,68 @@ static const struct iio_chan_spec hx711_chan_spec[] = {
 	IIO_CHAN_SOFT_TIMESTAMP(2),
 };
 
+/*
+ * HX710B channels (Table 3 in datasheet).
+ * 25 pulses (1 trailing): differential input, 10 SPS -> channel 0
+ * 26 pulses (2 trailing): DVDD-AVDD supply monitor, 40 SPS -> channel 2
+ * 27 pulses (3 trailing): differential input, 40 SPS -> channel 3
+ * .address stores the trailing pulse count for hx711_set_hx710b_channel().
+ * Channel 2 is used for the supply monitor to avoid aliasing the
+ * channel2 terminal of the first differential pair.
+ */
+static const struct iio_chan_spec hx710b_chan_spec[] = {
+	{
+		.type = IIO_VOLTAGE,
+		.differential = 1,
+		.channel = 0,
+		.channel2 = 1,
+		.indexed = 1,
+		.address = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 24,
+			.storagebits = 32,
+			.endianness = IIO_CPU,
+		},
+	},
+	{
+		.type = IIO_VOLTAGE,
+		.channel = 2,
+		.indexed = 1,
+		.address = 2,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 1,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 24,
+			.storagebits = 32,
+			.endianness = IIO_CPU,
+		},
+	},
+	{
+		.type = IIO_VOLTAGE,
+		.differential = 1,
+		.channel = 3,
+		.channel2 = 4,
+		.indexed = 1,
+		.address = 3,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 2,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 24,
+			.storagebits = 32,
+			.endianness = IIO_CPU,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(3),
+};
+
 static const struct hx711_chip_info hx711_chip = {
 	.name		= "hx711",
 	.channels	= hx711_chan_spec,
@@ -501,6 +612,15 @@ static const struct hx711_chip_info hx711_chip = {
 	.num_channels	= ARRAY_SIZE(hx711_chan_spec),
 };
 
+static const struct hx711_chip_info hx710b_chip = {
+	.name		= "hx710b",
+	.channels	= hx710b_chan_spec,
+	.iio_info	= &hx710b_iio_info,
+	.num_channels	= ARRAY_SIZE(hx710b_chan_spec),
+	.fixed_gain_val	= 128,
+	.has_fixed_gain	= true,
+};
+
 static int hx711_probe(struct platform_device *pdev)
 {
 	const struct hx711_chip_info *chip_info;
@@ -543,32 +663,42 @@ static int hx711_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, PTR_ERR(hx711_data->gpiod_dout),
 				     "failed to get dout-gpiod\n");
 
-	ret = devm_regulator_get_enable_read_voltage(dev, "avdd");
+	if (chip_info->has_fixed_gain)
+		ret = devm_regulator_get_enable_read_voltage(dev, "vref");
+	else
+		ret = devm_regulator_get_enable_read_voltage(dev, "avdd");
 	if (ret < 0)
 		return ret;
 
 	/*
-	 * with
-	 * full scale differential input range: AVDD / GAIN
+	 * With
+	 * full scale differential input range: reference / GAIN
 	 * full scale output data: 2^24
 	 * we can say:
-	 *     AVDD / GAIN = 2^24
+	 *     reference / GAIN = 2^24
 	 * therefore:
-	 *     1 LSB = AVDD / GAIN / 2^24
-	 * AVDD is in uV, but we need 10^-9 mV
+	 *     1 LSB = reference / GAIN / 2^24
+	 * reference is in uV, but we need 10^-9 mV
 	 * approximately to fit into a 32 bit number:
-	 * 1 LSB = (AVDD * 100) / GAIN / 1678 [10^-9 mV]
+	 * 1 LSB = (reference * 100) / GAIN / 1678 [10^-9 mV]
 	 */
 
 	/* we need 10^-9 mV */
 	ret *= 100;
 
-	for (i = 0; i < HX711_GAIN_MAX; i++)
-		hx711_data->gain_scale[i] =
-			ret / hx711_gain_to_scale[i].gain / 1678;
+	if (chip_info->has_fixed_gain) {
+		for (i = 0; i < HX711_GAIN_MAX; i++)
+			hx711_data->gain_scale[i] =
+				ret / chip_info->fixed_gain_val / 1678;
+		hx711_data->gain_set = chip_info->fixed_gain_val;
+	} else {
+		for (i = 0; i < HX711_GAIN_MAX; i++)
+			hx711_data->gain_scale[i] =
+				ret / hx711_gain_to_scale[i].gain / 1678;
 
-	hx711_data->gain_set = 128;
-	hx711_data->gain_chan_a = 128;
+		hx711_data->gain_set = 128;
+		hx711_data->gain_chan_a = 128;
+	}
 
 	hx711_data->clock_frequency = 400000;
 	ret = device_property_read_u32(&pdev->dev, "clock-frequency",
@@ -607,6 +737,7 @@ static int hx711_probe(struct platform_device *pdev)
 }
 
 static const struct of_device_id of_hx711_match[] = {
+	{ .compatible = "avia,hx710b", .data = &hx710b_chip },
 	{ .compatible = "avia,hx711", .data = &hx711_chip },
 	{ }
 };
@@ -624,6 +755,6 @@ static struct platform_driver hx711_driver = {
 module_platform_driver(hx711_driver);
 
 MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
-MODULE_DESCRIPTION("HX711 bitbanging driver - ADC for weight cells");
+MODULE_DESCRIPTION("HX711 and compatible bitbanging ADC driver");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:hx711-gpio");
-- 
2.43.0

Re: [PATCH v6 02/11] dt-bindings: iio: adc: hx711: add VSUP supply property

[Krzysztof Kozlowski]

On Sun, May 03, 2026 at 05:39:31PM +0530, Piyush Patle wrote:
> Document the optional VSUP supply used by the HX711 on-chip regulator.
> 
> Keep this separate from the HX710B support so the existing HX711

What does HX710B mean? There is no such device in this binding.

> binding extension stands on its own.
> 
> No functional change for existing users.

There is functional change - you added a new supply.

Best regards,
Krzysztof

Re: [PATCH v6 03/11] dt-bindings: iio: adc: hx711: add RATE GPIO property

[Krzysztof Kozlowski]

On Sun, May 03, 2026 at 05:39:32PM +0530, Piyush Patle wrote:
> Document the optional RATE pin GPIO used to select the HX711 output
> data rate.
> 
> Update the example to show the property in use.
> 
> No functional change for existing users.

You just changed existing binding for existing users, so this is a
functional change. Drop all such incorrect statements from your
patchset.

Best regards,
Krzysztof

Re: [PATCH v6 05/11] iio: adc: hx711: move scale computation to per-device storage

[Andy Shevchenko]

On Sun, May 03, 2026 at 05:39:34PM +0530, Piyush Patle wrote:
> The gain-to-scale table is global today, so probe-time scale updates for
> one device overwrite the values used by any earlier device instance.
> 
> Fix this by making the gain table const and storing the computed scale
> values per device in hx711_data.
> 
> No functional change for single-sensor configurations.

...

> +static const struct hx711_gain_to_scale hx711_gain_to_scale[HX711_GAIN_MAX] = {
> +	{ 128, 1, 0, },
> +	{  32, 2, 1, },
> +	{  64, 3, 0, },

In such case the inner trailing commas are not needed. They are needed when the
supplied lists are arrays and may be extended. Here it's a proper data type
with fixed number of arguments. If you want to be even stricter and robust, move
to C99 initialisers (but note, I'm fine with just trailing commas being removed).

	{ 128, 1, 0 },
	{  32, 2, 1 },
	{  64, 3, 0 },

>  };

...

> @@ -574,4 +575,3 @@ MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
>  MODULE_DESCRIPTION("HX711 bitbanging driver - ADC for weight cells");
>  MODULE_LICENSE("GPL");
>  MODULE_ALIAS("platform:hx711-gpio");
> -

Stray change.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 06/11] iio: adc: hx711: introduce hx711_chip_info structure

[Andy Shevchenko]

On Sun, May 03, 2026 at 05:39:35PM +0530, Piyush Patle wrote:
> Add a per-variant static configuration structure and populate the IIO
> device fields from it at probe time.
> 
> This is a preparatory change for adding support for more HX711-compatible
> hardware variants without duplicating the probe-time setup.
> 
> No functional change for existing HX711 users.

LGTM,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 08/11] iio: adc: hx711: split variable assignments in hx711_read and hx711_reset

[Andy Shevchenko]

On Sun, May 03, 2026 at 05:39:37PM +0530, Piyush Patle wrote:
> Separate the initial value assignments from the declarations in
> hx711_read() and hx711_reset().
> 
> This is a small preparatory cleanup before the later loop-iterator and
> variant-specific changes adjust the local variable layout in these
> functions.
> 
> No functional change.

...

>  	int i, ret;
>  	int value = 0;
> -	int val = gpiod_get_value(hx711_data->gpiod_dout);
> +	int val;
> +

> +	val = gpiod_get_value(hx711_data->gpiod_dout);

This line should be coupled with the conditional

>  
>  	/* we double check if it's really down */
>  	if (val)

	/* we double check if it's really down */
	val = gpiod_get_value(hx711_data->gpiod_dout);
	if (val)

...

>  static int hx711_reset(struct hx711_data *hx711_data)
>  {
> -	int val = hx711_wait_for_ready(hx711_data);
> +	int val;
> +
> +	val = hx711_wait_for_ready(hx711_data);
>  
>  	if (val) {

Ditto.

	val = hx711_wait_for_ready(hx711_data);
	if (val) {

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 09/11] iio: adc: hx711: localize loop iterators in hx711_read

[Andy Shevchenko]

On Sun, May 03, 2026 at 05:39:38PM +0530, Piyush Patle wrote:
> Tighten the scope of the loop variables in hx711_read() now that
> trailing-pulse selection is already handled by the callers.
> 
> Also replace the 24-bit loop bound with a named constant while touching
> the same code.

...

>  /* gain to pulse and scale conversion */

Does the comment stay for the _DATA_BITS? I am not sure it's semantically
correct to put the new definition under the same comment.

> +#define HX711_DATA_BITS		24
>  #define HX711_GAIN_MAX		3
>  #define HX711_RESET_GAIN	128

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 11/11] iio: adc: hx711: add support for HX710B

[Andy Shevchenko]

On Sun, May 03, 2026 at 05:39:40PM +0530, Piyush Patle wrote:
> Add support for the AVIA HX710B ADC, which shares the HX711 GPIO
> interface but uses trailing PD_SCK pulses to select the active mode.
> 
> Model the HX710B with variant-specific channel tables and IIO info,
> track the active channel across conversions, and use the fixed gain
> value when computing scale.
> 
> Also update the adjacent Kconfig text, file header, and module
> description so the driver text matches the newly supported variant.

...

>  	/*
>  	 * triggered buffer
> -	 * 2x32-bit channel + 64-bit naturally aligned timestamp
> +	 * up to 3x32-bit channels + pad + 64-bit naturally aligned timestamp
>  	 */
>  	struct {
> -		u32 channel[2];
> +		u32 channel[3];
> +		u32 pad;
>  		aligned_s64 timestamp;
>  	} buffer;

Maybe it's obvious to everybody, but me, however I find it difficult to see if
there is no ABI breakage. Can you add a comment explaining why this is not a
problem?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 00/11] iio: adc: hx711: add HX710B support

[Andy Shevchenko]

On Sun, May 03, 2026 at 05:39:29PM +0530, Piyush Patle wrote:
> Add support for the AVIA HX710B ADC, a HX711-compatible converter with
> the same GPIO interface but a different channel-selection model and a
> fixed gain of 128.
> 
> Compared to v5, this series is unchanged functionally and only folds in
> the remaining review nits:
> 
> - keep the per-variant probe local declarations in reversed xmas tree
>   order
> - add a preparatory split-assignment patch before the loop-iterator
>   cleanup, then keep the loop indices signed to match trailing_pulses
> - replace the 24-bit read loop bound with a named constant while
>   touching the same code
> - keep the driver wording aligned on "weigh sensor modules"
> - rename fixed_gain to has_fixed_gain and drop the channel_set cast
> 
> The DT binding split from v5 is kept as-is:
> 
> - cleanup of the existing HX711 binding text
> - HX711-only VSUP documentation
> - HX711-only RATE GPIO documentation
> - HX710B binding addition
> 
> Tested on PocketBeagle2 with an HX710B breakout module. The device
> probed successfully, all three channels returned stable raw readings,
> and alternating reads confirmed channel switching between the
> differential input and the DVDD-AVDD supply monitor path.
> 
> Build-tested with:
> - make -s W=1 drivers/iio/adc/hx711.o
> - make -s dt_binding_check \
>   DT_SCHEMA_FILES=Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
> - pahole -C hx711_chip_info drivers/iio/adc/hx711.o
> 
> pahole reports hx711_chip_info as 40 bytes with no internal holes. The
> remaining 7 bytes are tail padding from 8-byte pointer alignment.

Some small issues here and there, either Jonathan is going to tweak, or if
v7 is going to address them, feel free to add
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 02/11] dt-bindings: iio: adc: hx711: add VSUP supply property

[Jonathan Cameron]

On Mon, 4 May 2026 08:51:37 +0200
Krzysztof Kozlowski <krzk@kernel.org> wrote:

> On Sun, May 03, 2026 at 05:39:31PM +0530, Piyush Patle wrote:
> > Document the optional VSUP supply used by the HX711 on-chip regulator.
> > 
> > Keep this separate from the HX710B support so the existing HX711  
> 
> What does HX710B mean? There is no such device in this binding.

Yeah. Just drop this bit - it's reasoning that might belong in
a change log.

> 
> > binding extension stands on its own.
> > 
> > No functional change for existing users.  
> 
> There is functional change - you added a new supply.
> 
> Best regards,
> Krzysztof
> 

Re: [PATCH v6 05/11] iio: adc: hx711: move scale computation to per-device storage

[Jonathan Cameron]

On Mon, 4 May 2026 17:25:10 +0300
Andy Shevchenko <andriy.shevchenko@intel.com> wrote:

> On Sun, May 03, 2026 at 05:39:34PM +0530, Piyush Patle wrote:
> > The gain-to-scale table is global today, so probe-time scale updates for
> > one device overwrite the values used by any earlier device instance.
> > 
> > Fix this by making the gain table const and storing the computed scale
> > values per device in hx711_data.
> > 
> > No functional change for single-sensor configurations.  
> 
> ...
> 
> > +static const struct hx711_gain_to_scale hx711_gain_to_scale[HX711_GAIN_MAX] = {
> > +	{ 128, 1, 0, },
> > +	{  32, 2, 1, },
> > +	{  64, 3, 0, },  
> 
> In such case the inner trailing commas are not needed. They are needed when the
> supplied lists are arrays and may be extended. Here it's a proper data type
> with fixed number of arguments. If you want to be even stricter and robust, move
> to C99 initialisers (but note, I'm fine with just trailing commas being removed).
> 
> 	{ 128, 1, 0 },
> 	{  32, 2, 1 },
> 	{  64, 3, 0 },
> 
> >  };  
> 
> ...
> 
> > @@ -574,4 +575,3 @@ MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
> >  MODULE_DESCRIPTION("HX711 bitbanging driver - ADC for weight cells");
> >  MODULE_LICENSE("GPL");
> >  MODULE_ALIAS("platform:hx711-gpio");
> > -  
> 
> Stray change.
> 
Given Andy commented on this a couple of times and it is still here,
let me just add that this change is fine, but not in a patch doing
anything other that white space cleanup.  So spin a new patch for it
or don't make the change at all.  This stuff is distracting noise.

Thanks,

Jonathan

Re: [PATCH v6 11/11] iio: adc: hx711: add support for HX710B

[Jonathan Cameron]

On Sun,  3 May 2026 17:39:40 +0530
Piyush Patle <piyushpatle228@gmail.com> wrote:

> Add support for the AVIA HX710B ADC, which shares the HX711 GPIO
> interface but uses trailing PD_SCK pulses to select the active mode.
> 
> Model the HX710B with variant-specific channel tables and IIO info,
> track the active channel across conversions, and use the fixed gain
> value when computing scale.
> 
> Also update the adjacent Kconfig text, file header, and module
> description so the driver text matches the newly supported variant.
> 
> Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
Andy did suggest waiting for open questions he'd raised to be
resolved in the v5 discussions.  That would have save a little
time on this patch at least.  See what I wrote there.

Thanks,

Jonathan

Re: [PATCH v6 08/11] iio: adc: hx711: split variable assignments in hx711_read and hx711_reset

[Jonathan Cameron]

On Sun,  3 May 2026 17:39:37 +0530
Piyush Patle <piyushpatle228@gmail.com> wrote:

> Separate the initial value assignments from the declarations in
> hx711_read() and hx711_reset().
> 
> This is a small preparatory cleanup before the later loop-iterator and
> variant-specific changes adjust the local variable layout in these
> functions.
> 
> No functional change.
> 
> Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
> ---
>  drivers/iio/adc/hx711.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
> index 637114635867..b2de8db285b2 100644
> --- a/drivers/iio/adc/hx711.c
> +++ b/drivers/iio/adc/hx711.c
> @@ -159,7 +159,9 @@ static int hx711_read(struct hx711_data *hx711_data, int trailing_pulses)
>  {
>  	int i, ret;
>  	int value = 0;
> -	int val = gpiod_get_value(hx711_data->gpiod_dout);
> +	int val;
> +
> +	val = gpiod_get_value(hx711_data->gpiod_dout);

Not sure. Maybe Andy's feedback crossed with new version as I'm fairly sure
he commented on this in v5. Anyhow...
Remove this blank line.

>  
>  	/* we double check if it's really down */
>  	if (val)
> @@ -204,7 +206,9 @@ static int hx711_wait_for_ready(struct hx711_data *hx711_data)
>  
>  static int hx711_reset(struct hx711_data *hx711_data)
>  {
> -	int val = hx711_wait_for_ready(hx711_data);
> +	int val;
> +
> +	val = hx711_wait_for_ready(hx711_data);

And this blank line.

>  
>  	if (val) {
>  		/*

Re: [PATCH v6 10/11] iio: adc: hx711: pass iio_chan_spec to hx711_reset_read

[Jonathan Cameron]

On Sun,  3 May 2026 17:39:39 +0530
Piyush Patle <piyushpatle228@gmail.com> wrote:

> Change hx711_reset_read() to accept the channel descriptor directly and
> update its callers accordingly.
> 
> Split the existing HX711 channel-selection work into a small helper so a
> later variant-specific change can add a matching helper without growing
> hx711_reset_read() further.
> 
> No functional change.
> 
> Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
> ---
>  drivers/iio/adc/hx711.c | 26 ++++++++++++++++++++------
>  1 file changed, 20 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
> index 98fb617ea32b..2229df17f350 100644
> --- a/drivers/iio/adc/hx711.c
> +++ b/drivers/iio/adc/hx711.c
> @@ -269,7 +269,22 @@ static int hx711_set_gain_for_channel(struct hx711_data *hx711_data, int chan)
>  	return 0;
>  }
>  
> -static int hx711_reset_read(struct hx711_data *hx711_data, int chan)
> +static int hx711_set_hx711_channel(struct hx711_data *hx711_data,
> +				   const struct iio_chan_spec *chan,
> +				   int *trailing_pulses)
> +{
> +	int ret;
> +
> +	ret = hx711_set_gain_for_channel(hx711_data, chan->channel);
> +	if (ret < 0)
> +		return ret;
> +
> +	*trailing_pulses = hx711_get_gain_to_pulse(hx711_data->gain_set);
Really minor style thing that I'd have left if you weren't having to do
a v7 anyway.
When you have a 'bare' return like this that isn't directly related
to anything other than we reached the end of the function, my slight
preference it to add a blank line before it.  Some kernel reviewers
will insist on it, I just consider it good taste as makes the return
more obviously separate as a logical thing from the line above.

> +	return 0;
> +}
> +
> +static int hx711_reset_read(struct hx711_data *hx711_data,
> +			    const struct iio_chan_spec *chan)
>  {
>  	int trailing_pulses;
>  	int ret;
> @@ -283,11 +298,10 @@ static int hx711_reset_read(struct hx711_data *hx711_data, int chan)
>  		return -EIO;
>  	}
>  
> -	ret = hx711_set_gain_for_channel(hx711_data, chan);
> +	ret = hx711_set_hx711_channel(hx711_data, chan, &trailing_pulses);
>  	if (ret < 0)
>  		return ret;
>  
> -	trailing_pulses = hx711_get_gain_to_pulse(hx711_data->gain_set);
>  	return hx711_read(hx711_data, trailing_pulses);
>  }
>  
> @@ -301,7 +315,7 @@ static int hx711_read_raw(struct iio_dev *indio_dev,
>  	case IIO_CHAN_INFO_RAW:
>  		mutex_lock(&hx711_data->lock);
>  
> -		*val = hx711_reset_read(hx711_data, chan->channel);
> +		*val = hx711_reset_read(hx711_data, chan);
>  
>  		mutex_unlock(&hx711_data->lock);
>  
> @@ -391,8 +405,8 @@ static irqreturn_t hx711_trigger(int irq, void *p)
>  	memset(&hx711_data->buffer, 0, sizeof(hx711_data->buffer));
>  
>  	iio_for_each_active_channel(indio_dev, i) {
> -		hx711_data->buffer.channel[j] = hx711_reset_read(hx711_data,
> -					indio_dev->channels[i].channel);
> +		hx711_data->buffer.channel[j] =
> +			hx711_reset_read(hx711_data, &indio_dev->channels[i]);
>  		j++;
>  	}
>  

Re: [PATCH v6 11/11] iio: adc: hx711: add support for HX710B

[Jonathan Cameron]

On Mon, 4 May 2026 18:52:56 +0300
Andy Shevchenko <andriy.shevchenko@intel.com> wrote:

> On Sun, May 03, 2026 at 05:39:40PM +0530, Piyush Patle wrote:
> > Add support for the AVIA HX710B ADC, which shares the HX711 GPIO
> > interface but uses trailing PD_SCK pulses to select the active mode.
> > 
> > Model the HX710B with variant-specific channel tables and IIO info,
> > track the active channel across conversions, and use the fixed gain
> > value when computing scale.
> > 
> > Also update the adjacent Kconfig text, file header, and module
> > description so the driver text matches the newly supported variant.  
> 
> ...
> 
> >  	/*
> >  	 * triggered buffer
> > -	 * 2x32-bit channel + 64-bit naturally aligned timestamp
> > +	 * up to 3x32-bit channels + pad + 64-bit naturally aligned timestamp
> >  	 */
> >  	struct {
> > -		u32 channel[2];
> > +		u32 channel[3];
> > +		u32 pad;
> >  		aligned_s64 timestamp;
> >  	} buffer;  
> 
> Maybe it's obvious to everybody, but me, however I find it difficult to see if
> there is no ABI breakage. Can you add a comment explaining why this is not a
> problem?
> 
I replied in v5 (after this was out :)

It's not actually an ABI breakage, but only because the timestamp doesn't
land where this would make you think it does.  If there are less than 3 channels
enabled it lands 8 bytes in, so on top of channel[2] and the pad.

It is misleading which is why we don't use structures when it is possible to enable
a smaller set of channels and have the ones after them move up in the structure.
David add the stuff to declare buffers for this form - so we should use that.
See v5 reply as I've forgotten what the macro is called again ;)

Jonathan