Add maxim max34408/34409 ADC driver and yaml

The hardware binding for i2c current monitoring device with overcurrent control.

Signed-off-by Ivan Mikhaylov <[email protected]>

---
 .../bindings/iio/adc/maxim,max34408.yaml      | 101 ++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml

The hardware binding for i2c current monitoring device with overcurrent control.

Signed-off-by Ivan Mikhaylov <[email protected]>

---
 .../bindings/iio/adc/maxim,max34408.yaml      | 101 ++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +54 -0

new file mode 100644
index 000000000000..cdf89fa4c80e
@@ -0,0 +1,101 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/maxim,max34408.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Two- and four-channel current monitors with overcurrent control
+
+maintainers:
+  - Ivan Mikhaylov <[email protected]>
+
+description: |
+  The MAX34408/MAX34409 are two- and four-channel current monitors that are
+  configured and monitored with a standard I2C/SMBus serial interface. Each
+  unidirectional current sensor offers precision high-side operation with a
+  low full-scale sense voltage. The devices automatically sequence through
+  two or four channels and collect the current-sense samples and average them
+  to reduce the effect of impulse noise. The raw ADC samples are compared to
+  user-programmable digital thresholds to indicate overcurrent conditions.
+  Overcurrent conditions trigger a hardware output to provide an immediate
+  indication to shut down any necessary external circuitry.
+
+  Specifications about the devices can be found at:
+  https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf
+
+properties:
+  compatible:
+    enum:
+      - maxim,max34408
+      - maxim,max34409
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  maxim,input1-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 1.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000
+
+  maxim,input2-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 2.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000
+
+  maxim,input3-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +21 -0

+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@1e {
+              compatible = "maxim,max34409";
+              reg = <0x1e>;
+              maxim,input1-rsense-val-micro-ohms = <5000>;
+              maxim,input2-rsense-val-micro-ohms = <10000>;
+        };
+    };

Signature · 1 line

2.42.0

Hey,

Quoted 74 lines · Ivan Mikhaylov

The hardware binding for i2c current monitoring device with overcurrent control.

Signed-off-by Ivan Mikhaylov <[email protected]>

---
 .../bindings/iio/adc/maxim,max34408.yaml      | 101 ++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +59 -0

new file mode 100644
index 000000000000..cdf89fa4c80e
@@ -0,0 +1,101 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/maxim,max34408.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Two- and four-channel current monitors with overcurrent control
+
+maintainers:
+  - Ivan Mikhaylov <[email protected]>
+
+description: |
+  The MAX34408/MAX34409 are two- and four-channel current monitors that are
+  configured and monitored with a standard I2C/SMBus serial interface. Each
+  unidirectional current sensor offers precision high-side operation with a
+  low full-scale sense voltage. The devices automatically sequence through
+  two or four channels and collect the current-sense samples and average them
+  to reduce the effect of impulse noise. The raw ADC samples are compared to
+  user-programmable digital thresholds to indicate overcurrent conditions.
+  Overcurrent conditions trigger a hardware output to provide an immediate
+  indication to shut down any necessary external circuitry.
+
+  Specifications about the devices can be found at:
+  https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf
+
+properties:
+  compatible:
+    enum:
+      - maxim,max34408
+      - maxim,max34409
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  maxim,input1-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 1.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000
+
+  maxim,input2-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 2.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000
+
+  maxim,input3-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 3.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000
+
+  maxim,input4-rsense-val-micro-ohms:

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml line 64

Quoted 5 lines

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +5 -0

+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 4.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000  

Having 4 almost identical properties makes it seem like this should have some channel nodes, each containing an rsense-micro-ohms type property.

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml line 71

Quoted 8 lines

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +7 -0

+
+  maxim,shtdn:
+    description:
+      Shutdown Output. Open-drain output. This output transitions to high impedance
+      when any of the digital comparator thresholds are exceeded as long as the ENA
+      pin is high.
+    type: boolean  

I don't understand what this property is used for. The description here, and below for "ena", read like they are the descriptions in the datasheet for the pin, rather than how to use the property.

The drivers don't appear to contain users either - what is the point of these properties?

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml line 80

Quoted 9 lines

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +9 -0

+
+  maxim,ena:
+    description:
+      SHTDN Enable Input. CMOS digital input. Connect to GND to clear the latch and
+      unconditionally deassert (force low) the SHTDN output and reset the shutdown
+      delay. Connect to VDD to enable normal latch operation of the SHTDN output.
+    type: boolean
+
+  supply-vdd: true  

As pointed out by the bot, this is not correct. You need to use a -supply affix, not a supply-prefix.

Thanks,
Conor.

Quoted 24 lines

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +21 -0

+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@1e {
+              compatible = "maxim,max34409";
+              reg = <0x1e>;
+              maxim,input1-rsense-val-micro-ohms = <5000>;
+              maxim,input2-rsense-val-micro-ohms = <10000>;
+        };
+    };

Signature · 1 line

2.42.0

Hey,

Quoted 99 lines · Ivan Mikhaylov

The hardware binding for i2c current monitoring device with overcurrent
control.

Signed-off-by Ivan Mikhaylov <[email protected]>

---
 .../bindings/iio/adc/maxim,max34408.yaml      | 101
++++++++++++++++++

 1 file changed, 101 insertions(+)

 create mode 100644 Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml b/Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file mode 100644
index 000000000000..cdf89fa4c80e

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +7 -0

@@ -0,0 +1,101 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/maxim,max34408.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Two- and four-channel current monitors with overcurrent

control

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +6 -0

+
+maintainers:
+  - Ivan Mikhaylov <[email protected]>
+
+description: |
+  The MAX34408/MAX34409 are two- and four-channel current monitors

that are
+  configured and monitored with a standard I2C/SMBus serial interface. Each
+  unidirectional current sensor offers precision high-side operation with a
+  low full-scale sense voltage. The devices automatically sequence through
+  two or four channels and collect the current-sense samples and average them
+  to reduce the effect of impulse noise. The raw ADC samples are compared to
+  user-programmable digital thresholds to indicate overcurrent conditions.
+  Overcurrent conditions trigger a hardware output to provide an immediate
+  indication to shut down any necessary external circuitry. +
+  Specifications about the devices can be found at:
+
https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +16 -0

+
+properties:
+  compatible:
+    enum:
+      - maxim,max34408
+      - maxim,max34409
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  maxim,input1-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current

levels for
+      input 1.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000
+
+  maxim,input2-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 2.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000
+
+  maxim,input3-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 3.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000
+
+  maxim,input4-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 4.

Quoted 3 lines

+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000

Having 4 almost identical properties makes it seem like this should have
some channel nodes, each containing an rsense-micro-ohms type property.

Quoted 10 lines

+
+  maxim,shtdn:
+    description:
+      Shutdown Output. Open-drain output. This output transitions to high impedance
+      when any of the digital comparator thresholds are exceeded as long as the ENA
+      pin is high.
+    type: boolean

I don't understand what this property is used for. The description here,
and below for "ena", read like they are the descriptions in the datasheet for the pin, rather than how to use the property.

The drivers don't appear to contain users either - what is the point of
these properties?

Quoted 13 lines

+
+  maxim,ena:
+    description:
+      SHTDN Enable Input. CMOS digital input. Connect to GND to clear the latch and
+      unconditionally deassert (force low) the SHTDN output and reset the shutdown
+      delay. Connect to VDD to enable normal latch operation of the SHTDN output.
+    type: boolean
+
+  supply-vdd: true

As pointed out by the bot, this is not correct. You need to use a -supply affix, not a supply-prefix.

Quoted 102 lines · Conor Dooley

Hey,

Quoted 99 lines · Ivan Mikhaylov

The hardware binding for i2c current monitoring device with overcurrent
control.

Signed-off-by Ivan Mikhaylov <[email protected]>

---
 .../bindings/iio/adc/maxim,max34408.yaml      | 101
++++++++++++++++++

 1 file changed, 101 insertions(+)

 create mode 100644 Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml b/Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file mode 100644
index 000000000000..cdf89fa4c80e

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +7 -0

@@ -0,0 +1,101 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/maxim,max34408.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Two- and four-channel current monitors with overcurrent

control

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +6 -0

+
+maintainers:
+  - Ivan Mikhaylov <[email protected]>
+
+description: |
+  The MAX34408/MAX34409 are two- and four-channel current monitors

that are
+  configured and monitored with a standard I2C/SMBus serial interface. Each
+  unidirectional current sensor offers precision high-side operation with a
+  low full-scale sense voltage. The devices automatically sequence through
+  two or four channels and collect the current-sense samples and average them
+  to reduce the effect of impulse noise. The raw ADC samples are compared to
+  user-programmable digital thresholds to indicate overcurrent conditions.
+  Overcurrent conditions trigger a hardware output to provide an immediate
+  indication to shut down any necessary external circuitry. +
+  Specifications about the devices can be found at:
+
https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml new file +16 -0

+
+properties:
+  compatible:
+    enum:
+      - maxim,max34408
+      - maxim,max34409
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  maxim,input1-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current

levels for
+      input 1.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000
+
+  maxim,input2-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 2.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000
+
+  maxim,input3-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 3.
+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000
+
+  maxim,input4-rsense-val-micro-ohms:
+    description:
+      Adjust the Rsense value to monitor higher or lower current levels for
+      input 4.

Quoted 8 lines

Quoted 3 lines

+    enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+    default: 1000

Having 4 almost identical properties makes it seem like this should have
some channel nodes, each containing an rsense-micro-ohms type property.

Conor, I'll look through.

Quoted 16 lines

Quoted 10 lines

+
+  maxim,shtdn:
+    description:
+      Shutdown Output. Open-drain output. This output transitions to high impedance
+      when any of the digital comparator thresholds are exceeded as long as the ENA
+      pin is high.
+    type: boolean

I don't understand what this property is used for. The description here,
and below for "ena", read like they are the descriptions in the datasheet for the pin, rather than how to use the property.

Quoted 3 lines

The drivers don't appear to contain users either - what is the point of
these properties?

ena and shtdn physical pins of hardware, in the previous version Jonathan asked about adding them into yaml even if it's not used in code. should I do it in some other way?

Quoted 17 lines

Quoted 14 lines

+
+  maxim,ena:
+    description:
+      SHTDN Enable Input. CMOS digital input. Connect to GND to clear the latch and
+      unconditionally deassert (force low) the SHTDN output and reset the shutdown
+      delay. Connect to VDD to enable normal latch operation of the SHTDN output.
+    type: boolean
+
+  supply-vdd: true

As pointed out by the bot, this is not correct. You need to use a -supply affix, not a supply-prefix.

Oops.

Thanks.

The MAX34408/MAX34409 are two- and four-channel current monitors that are configured and monitored with a standard I2C/SMBus serial interface. Each unidirectional current sensor offers precision high-side operation with a low full-scale sense voltage. The devices automatically sequence through two or four channels and collect the current-sense samples and average them to reduce the effect of impulse noise. The raw ADC samples are compared to user-programmable digital thresholds to indicate overcurrent conditions. Overcurrent conditions trigger a hardware output to provide an immediate indication to shut down any necessary external circuitry.

Add as ADC driver which only supports current monitoring for now.

Link https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf

Signed-off-by Ivan Mikhaylov <[email protected]>

drivers/iio/adc/max34408.c new file +59 -0

new file mode 100644
index 000000000000..f576c65e3900
@@ -0,0 +1,334 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * IIO driver for Maxim MAX34409/34408 ADC, 4-Channels/2-Channels, 8bits, I2C
+ *
+ * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf
+ *
+ * TODO: ALERT interrupt, Overcurrent delay, Shutdown delay
+ */
+
+#include <linux/bitfield.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+
+#define MAX34408_STATUS_REG		0x0
+#define MAX34408_CONTROL_REG		0x1
+#define MAX34408_OCDELAY_REG		0x2
+#define MAX34408_SDDELAY_REG		0x3
+
+#define MAX34408_ADC1_REG		0x4
+#define MAX34408_ADC2_REG		0x5
+/* ADC3 & ADC4 always returns 0x0 on 34408 */
+#define MAX34409_ADC3_REG		0x6
+#define MAX34409_ADC4_REG		0x7
+
+#define MAX34408_OCT1_REG		0x8
+#define MAX34408_OCT2_REG		0x9
+#define MAX34408_OCT3_REG		0xA
+#define MAX34408_OCT4_REG		0xB
+
+#define MAX34408_DID_REG		0xC
+#define MAX34408_DCYY_REG		0xD
+#define MAX34408_DCWW_REG		0xE
+
+/* Bit masks for status register */
+#define MAX34408_STATUS_OC_MSK		GENMASK(1, 0)
+#define MAX34409_STATUS_OC_MSK		GENMASK(3, 0)
+#define MAX34408_STATUS_SHTDN		BIT(4)
+#define MAX34408_STATUS_ENA		BIT(5)
+
+/* Bit masks for control register */
+#define MAX34408_CONTROL_AVG0		BIT(0)
+#define MAX34408_CONTROL_AVG1		BIT(1)
+#define MAX34408_CONTROL_AVG2		BIT(2)
+#define MAX34408_CONTROL_ALERT		BIT(3)
+
+/* Bit masks for over current delay */
+#define MAX34408_OCDELAY_OCD_MSK	GENMASK(6, 0)
+#define MAX34408_OCDELAY_RESET		BIT(7)
+
+/* Bit masks for shutdown delay */
+#define MAX34408_SDDELAY_SHD_MSK	GENMASK(6, 0)
+#define MAX34408_SDDELAY_RESET		BIT(7)

drivers/iio/adc/max34408.c new file +17 -0

+ */
+struct max34408_data {
+	struct regmap *regmap;
+	struct device *dev;
+	struct mutex lock;
+	u32 input1_rsense;
+	u32 input2_rsense;
+	u32 input3_rsense;
+	u32 input4_rsense;
+};
+
+static const struct regmap_config max34408_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= MAX34408_DCWW_REG,
+};
+

drivers/iio/adc/max34408.c new file +16 -0

+					  BIT(IIO_CHAN_INFO_SCALE) |	\
+					  BIT(IIO_CHAN_INFO_OFFSET),	\
+		.channel = (_index),					\
+		.indexed = 1,						\
+	}
+
+static const struct iio_chan_spec max34408_channels[] = {
+	MAX34008_CHANNEL(0),
+	MAX34008_CHANNEL(1),
+};
+
+static const struct iio_chan_spec max34409_channels[] = {
+	MAX34008_CHANNEL(0),
+	MAX34008_CHANNEL(1),
+	MAX34008_CHANNEL(2),
+	MAX34008_CHANNEL(3),

drivers/iio/adc/max34408.c new file +23 -0

+		break;
+	case 1:
+		adc_reg = MAX34408_ADC2_REG;
+		break;
+	case 2:
+		adc_reg = MAX34409_ADC3_REG;
+		break;
+	case 3:
+		adc_reg = MAX34409_ADC4_REG;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return regmap_read(max34408->regmap, adc_reg, val);
+}
+
+static int max34408_read_adc_avg(struct max34408_data *max34408, int channel, int *val)
+{
+	unsigned int ctrl;
+	int rc;
+	u8 tmp;
+

drivers/iio/adc/max34408.c new file +22 -0

+	rc = regmap_write(max34408->regmap, MAX34408_CONTROL_REG, ctrl);
+	if (rc) {
+		dev_err(max34408->dev,
+			"Error (%d) writing control register\n", rc);
+		return rc;
+	}
+
+	rc = max34408_read_adc(max34408, channel, val);
+	if (rc)
+		return rc;
+
+	/* back to old values */
+	rc = regmap_write(max34408->regmap, MAX34408_CONTROL_REG, tmp);
+	if (rc)
+		dev_err(max34408->dev,
+			"Error (%d) writing control register\n", rc);
+
+	return rc;
+}
+
+static int max34408_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,

drivers/iio/adc/max34408.c new file +8 -0

+			break;
+		case 1:
+			input_rsense = max34408->input2_rsense;
+			break;
+		case 2:
+			input_rsense = max34408->input3_rsense;
+			break;
+		case 3:

drivers/iio/adc/max34408.c new file +9 -0

+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info max34408_info = {
+	.read_raw	= max34408_read_raw,
+};

drivers/iio/adc/max34408.c new file +44 -0

+static int max34408_probe(struct i2c_client *client)
+{
+	const struct max34408_adc_model_data *model_data;
+	const struct of_device_id *match;
+	struct max34408_data *max34408;
+	struct iio_dev *indio_dev;
+	struct regmap *regmap;
+	int rc;
+
+	match = of_match_device(max34408_of_match, &client->dev);
+	if (!match)
+		return -EINVAL;
+	model_data = match->data;
+
+	regmap = devm_regmap_init_i2c(client, &max34408_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err_probe(&client->dev, PTR_ERR(regmap),
+			      "regmap_init failed\n");
+		return PTR_ERR(regmap);
+	}
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*max34408));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	max34408 = iio_priv(indio_dev);
+	max34408->regmap = regmap;
+	max34408->dev = &client->dev;
+	mutex_init(&max34408->lock);
+
+	rc = device_property_read_u32(&client->dev,
+				      "maxim,input1-rsense-val-micro-ohms",
+				      &max34408->input1_rsense);
+	if (rc)
+		max34408->input1_rsense = MAX34408_DEFAULT_RSENSE;
+
+	rc = device_property_read_u32(&client->dev,
+				      "maxim,input2-rsense-val-micro-ohms",
+				      &max34408->input2_rsense);
+	if (rc)
+		max34408->input2_rsense = MAX34408_DEFAULT_RSENSE;
+
+	rc = device_property_read_u32(&client->dev,
+				      "maxim,input3-rsense-val-micro-ohms",