[PATCH v6 0/2] iio: amplifiers: add support for ADL8113 Low Noise Amplifier

[PATCH v6 0/2] iio: amplifiers: add support for ADL8113 Low Noise Amplifier

[Antoniu Miclaus]

This patch series adds support for the Analog Devices ADL8113, a 10MHz to 12GHz
Low Noise Amplifier with integrated bypass switches.

The ADL8113 provides four operation modes controlled by two GPIO pins:
- Internal Amplifier (14dB gain)
- Internal Bypass (-2dB insertion loss)
- External Bypass A (configurable gain) - Signal routes from RFIN to OUT_A and from IN_A to RFOUT
- External Bypass B (configurable gain) - Signal routes from RFIN to OUT_B and from IN_B to RFOUT

The driver allows selecting between these paths via the IIO hardwaregain attribute,
with optional external amplifier gains configured through device tree properties.

Antoniu Miclaus (2):
  dt-bindings: iio: amplifiers: add adl8113
  iio: amplifiers: adl8113: add driver support

 .../bindings/iio/amplifiers/adi,adl8113.yaml  |  87 ++++++
 drivers/iio/amplifiers/Kconfig                |  12 +
 drivers/iio/amplifiers/Makefile               |   1 +
 drivers/iio/amplifiers/adl8113.c              | 290 ++++++++++++++++++
 4 files changed, 390 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/amplifiers/adi,adl8113.yaml
 create mode 100644 drivers/iio/amplifiers/adl8113.c

-- 
2.43.0

[PATCH v6 1/2] dt-bindings: iio: amplifiers: add adl8113

[Antoniu Miclaus]

Add devicetree bindings for adl8113.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
changes in v6:
 - Use items list for ctrl-gpios instead of minItems/maxItems
 - Simplify ctrl-gpios item descriptions (remove GPIO_ACTIVE_HIGH mentions)
 - Remove maxItems (implied by items list)

 .../bindings/iio/amplifiers/adi,adl8113.yaml  | 87 +++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/amplifiers/adi,adl8113.yaml

diff --git a/Documentation/devicetree/bindings/iio/amplifiers/adi,adl8113.yaml b/Documentation/devicetree/bindings/iio/amplifiers/adi,adl8113.yaml
new file mode 100644
index 000000000000..28b3738cb675
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/amplifiers/adi,adl8113.yaml
@@ -0,0 +1,87 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/amplifiers/adi,adl8113.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices ADL8113 Low Noise Amplifier with integrated bypass switches
+
+maintainers:
+  - Antoniu Miclaus <antoniu.miclaus@analog.com>
+
+description: |
+  The ADL8113 is a 10MHz to 12GHz Low Noise Amplifier with integrated bypass
+  switches controlled by two GPIO pins (VA and VB). The device supports four
+  operation modes:
+    - Internal Amplifier: VA=0, VB=0 - Signal passes through the internal LNA
+    - Internal Bypass: VA=1, VB=1 - Signal bypasses through internal path
+    - External Bypass A: VA=0, VB=1 - Signal routes from RFIN to OUT_A and from IN_A to RFOUT
+    - External Bypass B: VA=1, VB=0 - Signal routes from RFIN to OUT_B and from IN_B to RFOUT
+
+    https://www.analog.com/en/products/adl8113.html
+
+properties:
+  compatible:
+    const: adi,adl8113
+
+  vdd1-supply: true
+
+  vdd2-supply: true
+
+  vss2-supply: true
+
+  ctrl-gpios:
+    items:
+      - description: VA control pin
+      - description: VB control pin
+
+  adi,external-bypass-a-gain-db:
+    description:
+      Gain in dB of external amplifier connected to bypass path A (OUT_A/IN_A).
+      When specified, this gain value becomes selectable via the hardwaregain
+      attribute and automatically routes through the external A path.
+
+  adi,external-bypass-b-gain-db:
+    description:
+      Gain in dB of external amplifier connected to bypass path B (OUT_B/IN_B).
+      When specified, this gain value becomes selectable via the hardwaregain
+      attribute and automatically routes through the external B path.
+
+required:
+  - compatible
+  - ctrl-gpios
+  - vdd1-supply
+  - vdd2-supply
+  - vss2-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    /* Basic configuration with only internal paths */
+    amplifier {
+        compatible = "adi,adl8113";
+        ctrl-gpios = <&gpio 22 GPIO_ACTIVE_HIGH>,
+                     <&gpio 23 GPIO_ACTIVE_HIGH>;
+        vdd1-supply = <&vdd1_5v>;
+        vdd2-supply = <&vdd2_3v3>;
+        vss2-supply = <&vss2_neg>;
+    };
+
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    /* Configuration with external bypass amplifiers */
+    amplifier {
+        compatible = "adi,adl8113";
+        ctrl-gpios = <&gpio 24 GPIO_ACTIVE_HIGH>,
+                     <&gpio 25 GPIO_ACTIVE_HIGH>;
+        vdd1-supply = <&vdd1_5v>;
+        vdd2-supply = <&vdd2_3v3>;
+        vss2-supply = <&vss2_neg>;
+        adi,external-bypass-a-gain-db = <20>;  /* 20dB external amp on path A */
+        adi,external-bypass-b-gain-db = <6>;   /* 6dB external amp on path B */
+    };
+...
-- 
2.43.0

[PATCH v6 2/2] iio: amplifiers: adl8113: add driver support

[Antoniu Miclaus]

Add support for adl8113 10MHz to 12GHz Low Noise Amplifier with
10MHz to 14GHz bypass switches.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
no changes in v6.
 drivers/iio/amplifiers/Kconfig   |  12 ++
 drivers/iio/amplifiers/Makefile  |   1 +
 drivers/iio/amplifiers/adl8113.c | 290 +++++++++++++++++++++++++++++++
 3 files changed, 303 insertions(+)
 create mode 100644 drivers/iio/amplifiers/adl8113.c

diff --git a/drivers/iio/amplifiers/Kconfig b/drivers/iio/amplifiers/Kconfig
index 55eb16b32f6c..a8a604863eed 100644
--- a/drivers/iio/amplifiers/Kconfig
+++ b/drivers/iio/amplifiers/Kconfig
@@ -36,6 +36,18 @@ config ADA4250
 	  To compile this driver as a module, choose M here: the
 	  module will be called ada4250.
 
+config ADL8113
+	tristate "Analog Devices ADL8113 Low Noise Amplifier"
+	depends on GPIOLIB
+	help
+	  Say yes here to build support for Analog Devices ADL8113 Low Noise
+	  Amplifier with integrated bypass switches. The device supports four
+	  operation modes controlled by GPIO pins: internal amplifier,
+	  internal bypass, and two external bypass modes.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called adl8113.
+
 config HMC425
 	tristate "Analog Devices HMC425A and similar GPIO Gain Amplifiers"
 	depends on GPIOLIB
diff --git a/drivers/iio/amplifiers/Makefile b/drivers/iio/amplifiers/Makefile
index 2126331129cf..0a76443be1aa 100644
--- a/drivers/iio/amplifiers/Makefile
+++ b/drivers/iio/amplifiers/Makefile
@@ -6,4 +6,5 @@
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_AD8366) += ad8366.o
 obj-$(CONFIG_ADA4250) += ada4250.o
+obj-$(CONFIG_ADL8113) += adl8113.o
 obj-$(CONFIG_HMC425) += hmc425a.o
diff --git a/drivers/iio/amplifiers/adl8113.c b/drivers/iio/amplifiers/adl8113.c
new file mode 100644
index 000000000000..eed5fe69280b
--- /dev/null
+++ b/drivers/iio/amplifiers/adl8113.c
@@ -0,0 +1,290 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ADL8113 Low Noise Amplifier with integrated bypass switches
+ *
+ * Copyright 2025 Analog Devices Inc.
+ */
+
+#include <linux/array_size.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+
+enum adl8113_signal_path {
+	ADL8113_INTERNAL_AMP,
+	ADL8113_INTERNAL_BYPASS,
+	ADL8113_EXTERNAL_A,
+	ADL8113_EXTERNAL_B,
+};
+
+struct adl8113_gain_config {
+	enum adl8113_signal_path path;
+	int gain_db;
+	int va;
+	int vb;
+};
+
+struct adl8113_state {
+	struct gpio_descs *gpios;
+	struct adl8113_gain_config *gain_configs;
+	int num_gain_configs;
+	enum adl8113_signal_path current_path;
+};
+
+static const char * const adl8113_supply_names[] = {
+	"vdd1",
+	"vss2",
+	"vdd2"
+};
+
+static int adl8113_set_path(struct adl8113_state *st,
+			    enum adl8113_signal_path path)
+{
+	DECLARE_BITMAP(values, 2);
+	int ret;
+
+	bitmap_zero(values, 2);
+
+	/* Determine GPIO values based on signal path */
+	switch (path) {
+	case ADL8113_INTERNAL_AMP:
+		/* va=0, vb=0 - already zero */
+		break;
+	case ADL8113_INTERNAL_BYPASS:
+		/* va=1, vb=1 */
+		__set_bit(0, values);
+		__set_bit(1, values);
+		break;
+	case ADL8113_EXTERNAL_A:
+		/* va=0, vb=1 */
+		__set_bit(1, values);
+		break;
+	case ADL8113_EXTERNAL_B:
+		/* va=1, vb=0 */
+		__set_bit(0, values);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = gpiod_set_array_value_cansleep(st->gpios->ndescs, st->gpios->desc,
+					     st->gpios->info, values);
+	if (ret)
+		return ret;
+
+	st->current_path = path;
+	return 0;
+}
+
+static int adl8113_find_gain_config(struct adl8113_state *st, int gain_db)
+{
+	int i;
+
+	for (i = 0; i < st->num_gain_configs; i++) {
+		if (st->gain_configs[i].gain_db == gain_db)
+			return i;
+	}
+	return -EINVAL;
+}
+
+static const struct iio_chan_spec adl8113_channels[] = {
+	{
+		.type = IIO_VOLTAGE,
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_HARDWAREGAIN),
+	},
+};
+
+static int adl8113_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct adl8113_state *st = iio_priv(indio_dev);
+	int i;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		/* Find current gain configuration */
+		for (i = 0; i < st->num_gain_configs; i++) {
+			if (st->gain_configs[i].path == st->current_path) {
+				*val = st->gain_configs[i].gain_db;
+				*val2 = 0;
+				return IIO_VAL_INT_PLUS_MICRO_DB;
+			}
+		}
+		return -EINVAL;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int adl8113_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct adl8113_state *st = iio_priv(indio_dev);
+	int config_idx;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		if (val2 != 0)
+			return -EINVAL;
+
+		config_idx = adl8113_find_gain_config(st, val);
+		if (config_idx < 0)
+			return config_idx;
+
+		return adl8113_set_path(st, st->gain_configs[config_idx].path);
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info adl8113_info = {
+	.read_raw = adl8113_read_raw,
+	.write_raw = adl8113_write_raw,
+};
+
+static int adl8113_init_gain_configs(struct device *dev, struct adl8113_state *st)
+{
+	int external_a_gain, external_b_gain, i = 0, j;
+
+	/*
+	 * Allocate for all 4 possible paths:
+	 * - Internal amp and bypass (always present)
+	 * - External bypass A and B (optional, or INT_MIN for testing)
+	 */
+	st->gain_configs = devm_kcalloc(dev, 4,
+					sizeof(*st->gain_configs), GFP_KERNEL);
+	if (!st->gain_configs)
+		return -ENOMEM;
+
+	/* Always include internal amplifier (14dB) */
+	st->gain_configs[i].path = ADL8113_INTERNAL_AMP;
+	st->gain_configs[i].gain_db = 14;
+	i++;
+
+	/* Always include internal bypass (-2dB insertion loss) */
+	st->gain_configs[i].path = ADL8113_INTERNAL_BYPASS;
+	st->gain_configs[i].gain_db = -2;
+	i++;
+
+	/* Add external bypass A if configured */
+	if (!device_property_read_u32(dev, "adi,external-bypass-a-gain-db",
+				      &external_a_gain)) {
+		st->gain_configs[i].path = ADL8113_EXTERNAL_A;
+		st->gain_configs[i].gain_db = external_a_gain;
+		i++;
+	}
+
+	/* Add external bypass B if configured */
+	if (!device_property_read_u32(dev, "adi,external-bypass-b-gain-db",
+				      &external_b_gain)) {
+		st->gain_configs[i].path = ADL8113_EXTERNAL_B;
+		st->gain_configs[i].gain_db = external_b_gain;
+		i++;
+	}
+
+	/*
+	 * If there's a free external bypass path, add one with INT_MIN gain
+	 * to represent "nothing connected" for testing purposes
+	 */
+	if (!device_property_present(dev, "adi,external-bypass-a-gain-db")) {
+		st->gain_configs[i].path = ADL8113_EXTERNAL_A;
+		st->gain_configs[i].gain_db = INT_MIN;
+		i++;
+	} else if (!device_property_present(dev, "adi,external-bypass-b-gain-db")) {
+		st->gain_configs[i].path = ADL8113_EXTERNAL_B;
+		st->gain_configs[i].gain_db = INT_MIN;
+		i++;
+	}
+
+	st->num_gain_configs = i;
+
+	/* Check for duplicate gain values */
+	for (i = 0; i < st->num_gain_configs - 1; i++) {
+		for (j = i + 1; j < st->num_gain_configs; j++) {
+			if (st->gain_configs[i].gain_db == st->gain_configs[j].gain_db)
+				return dev_err_probe(dev, -EINVAL,
+						     "Duplicate gain values not allowed: %d dB\n",
+						     st->gain_configs[i].gain_db);
+		}
+	}
+
+	return 0;
+}
+
+static int adl8113_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct adl8113_state *st;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	st->gpios = devm_gpiod_get_array(dev, "ctrl", GPIOD_OUT_LOW);
+	if (IS_ERR(st->gpios))
+		return dev_err_probe(dev, PTR_ERR(st->gpios),
+				     "failed to get control GPIOs\n");
+
+	if (st->gpios->ndescs != 2)
+		return dev_err_probe(dev, -EINVAL,
+				     "expected 2 control GPIOs, got %d\n",
+				     st->gpios->ndescs);
+
+	ret = devm_regulator_bulk_get_enable(dev,
+					     ARRAY_SIZE(adl8113_supply_names),
+					     adl8113_supply_names);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "failed to get and enable supplies\n");
+
+	/* Initialize gain configurations from devicetree */
+	ret = adl8113_init_gain_configs(dev, st);
+	if (ret)
+		return ret;
+
+	/* Initialize to internal amplifier path (14dB) */
+	ret = adl8113_set_path(st, ADL8113_INTERNAL_AMP);
+	if (ret)
+		return ret;
+
+	indio_dev->info = &adl8113_info;
+	indio_dev->name = "adl8113";
+	indio_dev->channels = adl8113_channels;
+	indio_dev->num_channels = ARRAY_SIZE(adl8113_channels);
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct of_device_id adl8113_of_match[] = {
+	{ .compatible = "adi,adl8113" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, adl8113_of_match);
+
+static struct platform_driver adl8113_driver = {
+	.driver = {
+		.name = "adl8113",
+		.of_match_table = adl8113_of_match,
+	},
+	.probe = adl8113_probe,
+};
+
+module_platform_driver(adl8113_driver);
+
+MODULE_AUTHOR("Antoniu Miclaus <antoniu.miclaus@analog.com>");
+MODULE_DESCRIPTION("Analog Devices ADL8113 Low Noise Amplifier");
+MODULE_LICENSE("GPL");
-- 
2.43.0

Re: [PATCH v6 2/2] iio: amplifiers: adl8113: add driver support

[Andy Shevchenko]

On Fri, Dec 05, 2025 at 04:40:41PM +0200, Antoniu Miclaus wrote:
> Add support for adl8113 10MHz to 12GHz Low Noise Amplifier with
> 10MHz to 14GHz bypass switches.

...

> no changes in v6.

This is surprisingly interesting.

https://lore.kernel.org/linux-iio/CAHp75VcxYGskVpQ5HKiFUUnNSj-9qpdXeBjz9-oEHc9eumE0fg@mail.gmail.com/

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 1/2] dt-bindings: iio: amplifiers: add adl8113

[Jonathan Cameron]

On Fri, 5 Dec 2025 16:40:40 +0200
Antoniu Miclaus <antoniu.miclaus@analog.com> wrote:

> Add devicetree bindings for adl8113.

If you roll a v7 I'd add some description of the 'interesting'
bit in here - which is the gains for the two external bypass paths.
I like the solution but i would like more eyes to focus on that!

Other than that this looks good to me. Maybe I'll add something
to this description if I apply this version.

Jonathan


> 
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> ---
> changes in v6:
>  - Use items list for ctrl-gpios instead of minItems/maxItems
>  - Simplify ctrl-gpios item descriptions (remove GPIO_ACTIVE_HIGH mentions)
>  - Remove maxItems (implied by items list)
> 
>  .../bindings/iio/amplifiers/adi,adl8113.yaml  | 87 +++++++++++++++++++
>  1 file changed, 87 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/amplifiers/adi,adl8113.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iio/amplifiers/adi,adl8113.yaml b/Documentation/devicetree/bindings/iio/amplifiers/adi,adl8113.yaml
> new file mode 100644
> index 000000000000..28b3738cb675
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/amplifiers/adi,adl8113.yaml
> @@ -0,0 +1,87 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/amplifiers/adi,adl8113.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices ADL8113 Low Noise Amplifier with integrated bypass switches
> +
> +maintainers:
> +  - Antoniu Miclaus <antoniu.miclaus@analog.com>
> +
> +description: |
> +  The ADL8113 is a 10MHz to 12GHz Low Noise Amplifier with integrated bypass
> +  switches controlled by two GPIO pins (VA and VB). The device supports four
> +  operation modes:
> +    - Internal Amplifier: VA=0, VB=0 - Signal passes through the internal LNA
> +    - Internal Bypass: VA=1, VB=1 - Signal bypasses through internal path
> +    - External Bypass A: VA=0, VB=1 - Signal routes from RFIN to OUT_A and from IN_A to RFOUT
> +    - External Bypass B: VA=1, VB=0 - Signal routes from RFIN to OUT_B and from IN_B to RFOUT
> +
> +    https://www.analog.com/en/products/adl8113.html
> +
> +properties:
> +  compatible:
> +    const: adi,adl8113
> +
> +  vdd1-supply: true
> +
> +  vdd2-supply: true
> +
> +  vss2-supply: true
> +
> +  ctrl-gpios:
> +    items:
> +      - description: VA control pin
> +      - description: VB control pin
> +
> +  adi,external-bypass-a-gain-db:
> +    description:
> +      Gain in dB of external amplifier connected to bypass path A (OUT_A/IN_A).
> +      When specified, this gain value becomes selectable via the hardwaregain
> +      attribute and automatically routes through the external A path.
> +
> +  adi,external-bypass-b-gain-db:
> +    description:
> +      Gain in dB of external amplifier connected to bypass path B (OUT_B/IN_B).
> +      When specified, this gain value becomes selectable via the hardwaregain
> +      attribute and automatically routes through the external B path.
> +
> +required:
> +  - compatible
> +  - ctrl-gpios
> +  - vdd1-supply
> +  - vdd2-supply
> +  - vss2-supply
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    /* Basic configuration with only internal paths */
> +    amplifier {
> +        compatible = "adi,adl8113";
> +        ctrl-gpios = <&gpio 22 GPIO_ACTIVE_HIGH>,
> +                     <&gpio 23 GPIO_ACTIVE_HIGH>;
> +        vdd1-supply = <&vdd1_5v>;
> +        vdd2-supply = <&vdd2_3v3>;
> +        vss2-supply = <&vss2_neg>;
> +    };
> +
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    /* Configuration with external bypass amplifiers */
> +    amplifier {
> +        compatible = "adi,adl8113";
> +        ctrl-gpios = <&gpio 24 GPIO_ACTIVE_HIGH>,
> +                     <&gpio 25 GPIO_ACTIVE_HIGH>;
> +        vdd1-supply = <&vdd1_5v>;
> +        vdd2-supply = <&vdd2_3v3>;
> +        vss2-supply = <&vss2_neg>;
> +        adi,external-bypass-a-gain-db = <20>;  /* 20dB external amp on path A */
> +        adi,external-bypass-b-gain-db = <6>;   /* 6dB external amp on path B */
> +    };
> +...

Re: [PATCH v6 2/2] iio: amplifiers: adl8113: add driver support

[Jonathan Cameron]

On Fri, 5 Dec 2025 16:40:41 +0200
Antoniu Miclaus <antoniu.miclaus@analog.com> wrote:

> Add support for adl8113 10MHz to 12GHz Low Noise Amplifier with
> 10MHz to 14GHz bypass switches.
> 
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> ---
Hi Antoniu,

> no changes in v6.
Given I assume you just missed Andy's prior review I'll take
a look at this version with assumption both sets of comments will be
sorted for v7.

A few things inline.

> diff --git a/drivers/iio/amplifiers/adl8113.c b/drivers/iio/amplifiers/adl8113.c
> new file mode 100644
> index 000000000000..eed5fe69280b
> --- /dev/null
> +++ b/drivers/iio/amplifiers/adl8113.c

> +struct adl8113_gain_config {
> +	enum adl8113_signal_path path;
> +	int gain_db;
> +	int va;
> +	int vb;

What are va and vb for?  Currently seem unused because you derive
them from path at use point.

> +};



> +
> +static const struct iio_info adl8113_info = {
> +	.read_raw = adl8113_read_raw,
> +	.write_raw = adl8113_write_raw,
> +};
> +
> +static int adl8113_init_gain_configs(struct device *dev, struct adl8113_state *st)
> +{
> +	int external_a_gain, external_b_gain, i = 0, j;

Preference for not hiding initializations in a list where only one is initialized.

	int external_a_gain, external_b_gain, j;
	int i = 0;

makes it easier to spot.

> +
> +	/*
> +	 * Allocate for all 4 possible paths:
> +	 * - Internal amp and bypass (always present)
> +	 * - External bypass A and B (optional, or INT_MIN for testing)
> +	 */
> +	st->gain_configs = devm_kcalloc(dev, 4,
> +					sizeof(*st->gain_configs), GFP_KERNEL);

Slightly odd wrap. I'd move the sizeof() up a line.

> +	if (!st->gain_configs)
> +		return -ENOMEM;
> +
> +	/* Always include internal amplifier (14dB) */
> +	st->gain_configs[i].path = ADL8113_INTERNAL_AMP;
> +	st->gain_configs[i].gain_db = 14;

Could do this as something like:

	st->gain_configs[i++] = (struct adl8113_gain_config) {
		.path = ADL8113_INTERNAL_AMP,
		.gain_db = 14,
	};

	st->gain_configs[i++] = (struct adl8113_gain_config) {
		.path = ADL8113_INTERNAL_BYPASS,
		.gain_db = -2,
	};

etc.

> +	i++;
> +
> +	/* Always include internal bypass (-2dB insertion loss) */
> +	st->gain_configs[i].path = ADL8113_INTERNAL_BYPASS;
> +	st->gain_configs[i].gain_db = -2;
> +	i++;
> +
> +	/* Add external bypass A if configured */
> +	if (!device_property_read_u32(dev, "adi,external-bypass-a-gain-db",
> +				      &external_a_gain)) {
> +		st->gain_configs[i].path = ADL8113_EXTERNAL_A;
> +		st->gain_configs[i].gain_db = external_a_gain;
> +		i++;
> +	}
> +
> +	/* Add external bypass B if configured */
> +	if (!device_property_read_u32(dev, "adi,external-bypass-b-gain-db",
> +				      &external_b_gain)) {
> +		st->gain_configs[i].path = ADL8113_EXTERNAL_B;
> +		st->gain_configs[i].gain_db = external_b_gain;
> +		i++;
> +	}
> +
> +	/*
> +	 * If there's a free external bypass path, add one with INT_MIN gain
> +	 * to represent "nothing connected" for testing purposes

I don't follow this one.  What sort of testing purpose?  Something we want
in a real system?

> +	 */
> +	if (!device_property_present(dev, "adi,external-bypass-a-gain-db")) {
> +		st->gain_configs[i].path = ADL8113_EXTERNAL_A;
> +		st->gain_configs[i].gain_db = INT_MIN;
> +		i++;
> +	} else if (!device_property_present(dev, "adi,external-bypass-b-gain-db")) {
> +		st->gain_configs[i].path = ADL8113_EXTERNAL_B;
> +		st->gain_configs[i].gain_db = INT_MIN;
> +		i++;
> +	}
> +
> +	st->num_gain_configs = i;
> +
> +	/* Check for duplicate gain values */
> +	for (i = 0; i < st->num_gain_configs - 1; i++) {
> +		for (j = i + 1; j < st->num_gain_configs; j++) {
> +			if (st->gain_configs[i].gain_db == st->gain_configs[j].gain_db)
> +				return dev_err_probe(dev, -EINVAL,
> +						     "Duplicate gain values not allowed: %d dB\n",
> +						     st->gain_configs[i].gain_db);

What happens if we just don't bother enforcing this? I assume the second of the duplicates
can't be selected?  Do we care beyond it being silly?

> +		}
> +	}
> +
> +	return 0;
> +}

Re: [PATCH v6 2/2] iio: amplifiers: adl8113: add driver support

[Andy Shevchenko]

On Sat, Dec 06, 2025 at 07:03:32PM +0000, Jonathan Cameron wrote:
> On Fri, 5 Dec 2025 16:40:41 +0200
> Antoniu Miclaus <antoniu.miclaus@analog.com> wrote:

...

> > +	/* Always include internal amplifier (14dB) */
> > +	st->gain_configs[i].path = ADL8113_INTERNAL_AMP;
> > +	st->gain_configs[i].gain_db = 14;
> 
> Could do this as something like:

I remember a discussion where it was against this approach due to compiler
warnings or so. However, IIRC, there was slightly different pattern, i.e.

	foo[i].bar = ...
	foo[i++].baz = ...

That said, I have no objection to your proposal, but we need to use it with
a good compile test coverage (clang with `make W=1` for a starter.

OTOH, the original code is robust enough...

> 	st->gain_configs[i++] = (struct adl8113_gain_config) {
> 		.path = ADL8113_INTERNAL_AMP,
> 		.gain_db = 14,
> 	};

...and doesn't require a good understanding of differences between designated
initialisers and compound literals.

> 	st->gain_configs[i++] = (struct adl8113_gain_config) {
> 		.path = ADL8113_INTERNAL_BYPASS,
> 		.gain_db = -2,
> 	};


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 2/2] iio: amplifiers: adl8113: add driver support

[Jonathan Cameron]

On Sat, 6 Dec 2025 22:48:19 +0200
Andy Shevchenko <andriy.shevchenko@intel.com> wrote:

> On Sat, Dec 06, 2025 at 07:03:32PM +0000, Jonathan Cameron wrote:
> > On Fri, 5 Dec 2025 16:40:41 +0200
> > Antoniu Miclaus <antoniu.miclaus@analog.com> wrote:  
> 
> ...
> 
> > > +	/* Always include internal amplifier (14dB) */
> > > +	st->gain_configs[i].path = ADL8113_INTERNAL_AMP;
> > > +	st->gain_configs[i].gain_db = 14;  
> > 
> > Could do this as something like:  
> 
> I remember a discussion where it was against this approach due to compiler
> warnings or so. However, IIRC, there was slightly different pattern, i.e.
> 
> 	foo[i].bar = ...
> 	foo[i++].baz = ...
> 
> That said, I have no objection to your proposal, but we need to use it with
> a good compile test coverage (clang with `make W=1` for a starter.

That's my standard 1st build choice now because it seems to be fussiest ;)
I haven't tried this one however.

Googling came up with a link saying GCC gives warnings on cases where
not all structure elements are set.  I think they always should be here
though which may make this fine (and act as a correct warning if they aren't).
That only works if the two uninitialized structure elements are dropped
obviously!

> 
> OTOH, the original code is robust enough...
> 
> > 	st->gain_configs[i++] = (struct adl8113_gain_config) {
> > 		.path = ADL8113_INTERNAL_AMP,
> > 		.gain_db = 14,
> > 	};  
> 
> ...and doesn't require a good understanding of differences between designated
> initialisers and compound literals.

Fair enough.  Original is better than the i++ in only the second in my view.

Jonathan

> 
> > 	st->gain_configs[i++] = (struct adl8113_gain_config) {
> > 		.path = ADL8113_INTERNAL_BYPASS,
> > 		.gain_db = -2,
> > 	};  
> 
> 

Re: [PATCH v6 1/2] dt-bindings: iio: amplifiers: add adl8113

[Rob Herring (Arm)]

On Fri, 05 Dec 2025 16:40:40 +0200, Antoniu Miclaus wrote:
> Add devicetree bindings for adl8113.
> 
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> ---
> changes in v6:
>  - Use items list for ctrl-gpios instead of minItems/maxItems
>  - Simplify ctrl-gpios item descriptions (remove GPIO_ACTIVE_HIGH mentions)
>  - Remove maxItems (implied by items list)
> 
>  .../bindings/iio/amplifiers/adi,adl8113.yaml  | 87 +++++++++++++++++++
>  1 file changed, 87 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/amplifiers/adi,adl8113.yaml
> 

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>

RE: [PATCH v6 2/2] iio: amplifiers: adl8113: add driver support

[Miclaus, Antoniu]

Hi,
> 
> Could do this as something like:
> 
> 	st->gain_configs[i++] = (struct adl8113_gain_config) {
> 		.path = ADL8113_INTERNAL_AMP,
> 		.gain_db = 14,
> 	};
> 
> 	st->gain_configs[i++] = (struct adl8113_gain_config) {
> 		.path = ADL8113_INTERNAL_BYPASS,
> 		.gain_db = -2,
> 	};
> 
> etc.
> 
> > +	i++;
> > +
> > +	/* Always include internal bypass (-2dB insertion loss) */
> > +	st->gain_configs[i].path = ADL8113_INTERNAL_BYPASS;
> > +	st->gain_configs[i].gain_db = -2;
> > +	i++;
> > +
> > +	/* Add external bypass A if configured */
> > +	if (!device_property_read_u32(dev, "adi,external-bypass-a-gain-db",
> > +				      &external_a_gain)) {
> > +		st->gain_configs[i].path = ADL8113_EXTERNAL_A;
> > +		st->gain_configs[i].gain_db = external_a_gain;
> > +		i++;
> > +	}
> > +
> > +	/* Add external bypass B if configured */
> > +	if (!device_property_read_u32(dev, "adi,external-bypass-b-gain-db",
> > +				      &external_b_gain)) {
> > +		st->gain_configs[i].path = ADL8113_EXTERNAL_B;
> > +		st->gain_configs[i].gain_db = external_b_gain;
> > +		i++;
> > +	}
> > +
> > +	/*
> > +	 * If there's a free external bypass path, add one with INT_MIN gain
> > +	 * to represent "nothing connected" for testing purposes
> 
> I don't follow this one.  What sort of testing purpose?  Something we want
> in a real system?
This addition was suggested by David in v4. But I can revert it in the next series.

Regards,
Antoniu

Re: [PATCH v6 2/2] iio: amplifiers: adl8113: add driver support

[Jonathan Cameron]

On Fri, 12 Dec 2025 10:41:07 +0000
"Miclaus, Antoniu" <Antoniu.Miclaus@analog.com> wrote:

> Hi,
> > 
> > Could do this as something like:
> > 
> > 	st->gain_configs[i++] = (struct adl8113_gain_config) {
> > 		.path = ADL8113_INTERNAL_AMP,
> > 		.gain_db = 14,
> > 	};
> > 
> > 	st->gain_configs[i++] = (struct adl8113_gain_config) {
> > 		.path = ADL8113_INTERNAL_BYPASS,
> > 		.gain_db = -2,
> > 	};
> > 
> > etc.
> >   
> > > +	i++;
> > > +
> > > +	/* Always include internal bypass (-2dB insertion loss) */
> > > +	st->gain_configs[i].path = ADL8113_INTERNAL_BYPASS;
> > > +	st->gain_configs[i].gain_db = -2;
> > > +	i++;
> > > +
> > > +	/* Add external bypass A if configured */
> > > +	if (!device_property_read_u32(dev, "adi,external-bypass-a-gain-db",
> > > +				      &external_a_gain)) {
> > > +		st->gain_configs[i].path = ADL8113_EXTERNAL_A;
> > > +		st->gain_configs[i].gain_db = external_a_gain;
> > > +		i++;
> > > +	}
> > > +
> > > +	/* Add external bypass B if configured */
> > > +	if (!device_property_read_u32(dev, "adi,external-bypass-b-gain-db",
> > > +				      &external_b_gain)) {
> > > +		st->gain_configs[i].path = ADL8113_EXTERNAL_B;
> > > +		st->gain_configs[i].gain_db = external_b_gain;
> > > +		i++;
> > > +	}
> > > +
> > > +	/*
> > > +	 * If there's a free external bypass path, add one with INT_MIN gain
> > > +	 * to represent "nothing connected" for testing purposes  
> > 
> > I don't follow this one.  What sort of testing purpose?  Something we want
> > in a real system?  
> This addition was suggested by David in v4. But I can revert it in the next series.
Ok. I looked back and found it.  I don't mind this feature with
more explanation.  However, I'm not sure it's actually useful other than for
replicating figure 121 on the datasheet which I can't really see as particularly
useful for testing.  Mind you I've no real idea how these are used :)

Jonathan

> 
> Regards,
> Antoniu