[PATCH v3 0/3] Add devicetree support for max6639

[PATCH v3 0/3] Add devicetree support for max6639

[Naresh Solanki]

These patches adds devicetree support for MAX6639.

Changes V3:
- correct fan dt property name
- remove unrelevent changes
Changes V2:
- Fix dt schema error.
Changes:
- Add fan-common dt schema.
- add dt-binding support for max6639
- add max6639 specific property

Marcello Sylvester Bauer (1):
  dt-bindings: hwmon: Add binding for max6639

Naresh Solanki (2):
  dt-bindings: hwmon: fan: Add fan binding to schema
  hwmon: (max6639) Change from pdata to dt configuration

 .../devicetree/bindings/hwmon/fan-common.yaml |  48 ++++
 .../bindings/hwmon/maxim,max6639.yaml         |  86 ++++++++
 drivers/hwmon/max6639.c                       | 206 +++++++++++++-----
 3 files changed, 286 insertions(+), 54 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/hwmon/fan-common.yaml
 create mode 100644 Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml


base-commit: 0cf46a653bdae56683fece68dc50340f7520e6c4
-- 
2.37.3

[PATCH v3 1/3] dt-bindings: hwmon: fan: Add fan binding to schema

[Naresh Solanki]

Add common fan properties bindings to a schema.

Bindings for fan controllers can reference the common schema for the
fan

child nodes:

  patternProperties:
    "^fan@[0-2]":
      type: object
      $ref: fan-common.yaml#

Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>
---
 .../devicetree/bindings/hwmon/fan-common.yaml | 48 +++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/fan-common.yaml

diff --git a/Documentation/devicetree/bindings/hwmon/fan-common.yaml b/Documentation/devicetree/bindings/hwmon/fan-common.yaml
new file mode 100644
index 000000000000..224f5013c93f
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/fan-common.yaml
@@ -0,0 +1,48 @@
+# SPDX-License-Identifier: GPL-2.0-or-later OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/fan-common.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Common fan properties
+
+maintainers:
+  - Naresh Solanki <naresh.solanki@9elements.com>
+
+properties:
+  max-rpm:
+    description:
+      Max RPM supported by fan.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  pulses-per-revolution:
+    description:
+      The number of pulse from fan sensor per revolution.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  default-rpm:
+    description:
+      Target RPM the fan should be configured during driver probe.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  pwm-frequency:
+    description:
+      PWM frequency for fan in Hertz(Hz).
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  pwm-polarity-inverse:
+    description:
+      Inverse PWM polarity for fan.
+    type: boolean
+
+  label:
+    description:
+      Optional fan label
+
+  fan-supply:
+    description:
+      Power supply for fan.
+
+additionalProperties: true
+
+...

base-commit: 0cf46a653bdae56683fece68dc50340f7520e6c4
-- 
2.37.3

[PATCH v3 2/3] dt-bindings: hwmon: Add binding for max6639

[Naresh Solanki]

From: Marcello Sylvester Bauer <sylv@sylv.io>

Add Devicetree binding documentation for Maxim MAX6639 temperature
monitor with PWM fan-speed controller.

Signed-off-by: Marcello Sylvester Bauer <sylv@sylv.io>
Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>
---
 .../bindings/hwmon/maxim,max6639.yaml         | 86 +++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml

diff --git a/Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml b/Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml
new file mode 100644
index 000000000000..459647870ebc
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml
@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+
+$id: http://devicetree.org/schemas/hwmon/maxim,max6639.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim max6639
+
+maintainers:
+  - Roland Stigge <stigge@antcom.de>
+
+description: |
+  The MAX6639 is a 2-channel temperature monitor with dual, automatic, PWM
+  fan-speed controller.  It monitors its own temperature and one external
+  diode-connected transistor or the temperatures of two external diode-connected
+  transistors, typically available in CPUs, FPGAs, or GPUs.
+
+  Datasheets:
+    https://datasheets.maximintegrated.com/en/ds/MAX6639-MAX6639F.pdf
+
+properties:
+  compatible:
+    enum:
+      - maxim,max6639
+
+  reg:
+    maxItems: 1
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+required:
+  - compatible
+  - reg
+
+patternProperties:
+  "^fan@[0-1]$":
+    type: object
+    description: |
+      Represents the two fans and their specific configuration.
+
+    $ref: fan-common.yaml#
+
+    properties:
+      reg:
+        description: |
+          The fan number.
+        items:
+          minimum: 0
+          maximum: 1
+
+    required:
+      - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      fan-controller@2e {
+        compatible = "maxim,max6639";
+        reg = <0x10>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        fan@0 {
+          reg = <0x0>;
+          pulses-per-revolution = <2>;
+          max-rpm = <4000>;
+        };
+
+        fan@1 {
+          reg = <0x1>;
+          pulses-per-revolution = <2>;
+          max-rpm = <8000>;
+        };
+      };
+    };
+...
-- 
2.37.3

Re: [PATCH v3 2/3] dt-bindings: hwmon: Add binding for max6639

[Rob Herring]

On Wed, 12 Oct 2022 22:57:35 +0200, Naresh Solanki wrote:
> From: Marcello Sylvester Bauer <sylv@sylv.io>
> 
> Add Devicetree binding documentation for Maxim MAX6639 temperature
> monitor with PWM fan-speed controller.
> 
> Signed-off-by: Marcello Sylvester Bauer <sylv@sylv.io>
> Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>
> ---
>  .../bindings/hwmon/maxim,max6639.yaml         | 86 +++++++++++++++++++
>  1 file changed, 86 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:

dtschema/dtc warnings/errors:
Documentation/devicetree/bindings/hwmon/maxim,max6639.example.dts:22.29-39.13: Warning (i2c_bus_reg): /example-0/i2c/fan-controller@2e: I2C bus unit address format error, expected "10"

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/patch/

This check can fail if there are any dependencies. The base for a patch
series is generally the most recent rc1.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit.

[PATCH v3 3/3] hwmon: (max6639) Change from pdata to dt configuration

[Naresh Solanki]

max6639_platform_data is not used by any in-kernel driver and does not
address the MAX6639 fans separately.
Move to device tree configuration with explicit properties to configure
each fan.

Non-DT platform can still use this module with its default
configuration.

Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>
---
 drivers/hwmon/max6639.c | 205 +++++++++++++++++++++++++++++-----------
 1 file changed, 152 insertions(+), 53 deletions(-)

diff --git a/drivers/hwmon/max6639.c b/drivers/hwmon/max6639.c
index 9b895402c80d..2fc096a00e21 100644
--- a/drivers/hwmon/max6639.c
+++ b/drivers/hwmon/max6639.c
@@ -19,7 +19,6 @@
 #include <linux/hwmon-sysfs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
-#include <linux/platform_data/max6639.h>
 
 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x2c, 0x2e, 0x2f, I2C_CLIENT_END };
@@ -85,9 +84,9 @@ struct max6639_data {
 	u8 temp_ot[2];		/* OT Temperature, 0..255 C (->_emergency) */
 
 	/* Register values initialized only once */
-	u8 ppr;			/* Pulses per rotation 0..3 for 1..4 ppr */
-	u8 rpm_range;		/* Index in above rpm_ranges table */
-
+	u8 ppr[2];		/* Pulses per rotation 0..3 for 1..4 ppr */
+	u8 rpm_range[2];	/* Index in above rpm_ranges table */
+	u8 pwm_polarity[2];	/* Fans PWM polarity, 0..1 */
 	/* Optional regulator for FAN supply */
 	struct regulator *reg;
 };
@@ -319,7 +318,7 @@ static ssize_t fan_input_show(struct device *dev,
 		return PTR_ERR(data);
 
 	return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan[attr->index],
-		       data->rpm_range));
+		       data->rpm_range[attr->index]));
 }
 
 static ssize_t alarm_show(struct device *dev,
@@ -386,29 +385,39 @@ static struct attribute *max6639_attrs[] = {
 ATTRIBUTE_GROUPS(max6639);
 
 /*
- *  returns respective index in rpm_ranges table
- *  1 by default on invalid range
+ *  Get respective index in rpm_ranges table
  */
-static int rpm_range_to_reg(int range)
+static int rpm_range_to_index(struct device *dev, u8 *index, int rpm)
 {
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(rpm_ranges); i++) {
-		if (rpm_ranges[i] == range)
-			return i;
+	if (rpm < 0)
+		return -EINVAL;
+
+	/* Set index based on chip support */
+	switch (rpm) {
+	case 0 ... 2000:
+		*index = 0;
+		break;
+	case 2001 ... 4000:
+		*index = 1;
+		break;
+	case 4001 ... 8000:
+		*index = 2;
+		break;
+	case 8001 ... 16000:
+		*index = 3;
+		break;
+	default:
+		/* Use max range for higher RPM */
+		dev_warn(dev, "RPM higher than supported range.");
+		*index = 3;
 	}
-
-	return 1; /* default: 4000 RPM */
+	return 0;
 }
 
 static int max6639_init_client(struct i2c_client *client,
 			       struct max6639_data *data)
 {
-	struct max6639_platform_data *max6639_info =
-		dev_get_platdata(&client->dev);
-	int i;
-	int rpm_range = 1; /* default: 4000 RPM */
-	int err;
+	int i, err;
 
 	/* Reset chip to default values, see below for GCONFIG setup */
 	err = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
@@ -416,51 +425,32 @@ static int max6639_init_client(struct i2c_client *client,
 	if (err)
 		goto exit;
 
-	/* Fans pulse per revolution is 2 by default */
-	if (max6639_info && max6639_info->ppr > 0 &&
-			max6639_info->ppr < 5)
-		data->ppr = max6639_info->ppr;
-	else
-		data->ppr = 2;
-	data->ppr -= 1;
-
-	if (max6639_info)
-		rpm_range = rpm_range_to_reg(max6639_info->rpm_range);
-	data->rpm_range = rpm_range;
-
 	for (i = 0; i < 2; i++) {
 
 		/* Set Fan pulse per revolution */
 		err = i2c_smbus_write_byte_data(client,
 				MAX6639_REG_FAN_PPR(i),
-				data->ppr << 6);
+				data->ppr[i] << 6);
 		if (err)
 			goto exit;
 
 		/* Fans config PWM, RPM */
 		err = i2c_smbus_write_byte_data(client,
 			MAX6639_REG_FAN_CONFIG1(i),
-			MAX6639_FAN_CONFIG1_PWM | rpm_range);
+			MAX6639_FAN_CONFIG1_PWM | data->rpm_range[i]);
 		if (err)
 			goto exit;
 
-		/* Fans PWM polarity high by default */
-		if (max6639_info && max6639_info->pwm_polarity == 0)
-			err = i2c_smbus_write_byte_data(client,
-				MAX6639_REG_FAN_CONFIG2a(i), 0x00);
-		else
-			err = i2c_smbus_write_byte_data(client,
-				MAX6639_REG_FAN_CONFIG2a(i), 0x02);
-		if (err)
-			goto exit;
+		/* Fans PWM polarity */
+		err = i2c_smbus_write_byte_data(client,
+			MAX6639_REG_FAN_CONFIG2a(i), data->pwm_polarity[i] ? 0x02 : 0x00);
 
 		/*
-		 * /THERM full speed enable,
+		 * /THERM full speed disable,
 		 * PWM frequency 25kHz, see also GCONFIG below
 		 */
 		err = i2c_smbus_write_byte_data(client,
-			MAX6639_REG_FAN_CONFIG3(i),
-			MAX6639_FAN_CONFIG3_THERM_FULL_SPEED | 0x03);
+			MAX6639_REG_FAN_CONFIG3(i), 0x03);
 		if (err)
 			goto exit;
 
@@ -483,8 +473,6 @@ static int max6639_init_client(struct i2c_client *client,
 		if (err)
 			goto exit;
 
-		/* PWM 120/120 (i.e. 100%) */
-		data->pwm[i] = 120;
 		err = i2c_smbus_write_byte_data(client,
 				MAX6639_REG_TARGTDUTY(i), data->pwm[i]);
 		if (err)
@@ -524,12 +512,92 @@ static void max6639_regulator_disable(void *data)
 	regulator_disable(data);
 }
 
+static int max6639_probe_child_from_dt(struct i2c_client *client,
+				      struct device_node *child,
+				      struct max6639_data *data)
+
+{
+	struct device *dev = &client->dev;
+	u32 i, val, maxrpm;
+	int err;
+
+	err = of_property_read_u32(child, "reg", &i);
+	if (err) {
+		dev_err(dev, "missing reg property of %pOFn\n", child);
+		return err;
+	}
+
+	if (i >= 2) {
+		dev_err(dev, "invalid reg %d of %pOFn\n", i, child);
+		return -EINVAL;
+	}
+
+	err = of_property_read_u32(child, "pulses-per-revolution", &val);
+	if (err) {
+		dev_err(dev, "missing pulses-per-revolution property of %pOFn\n", child);
+		return err;
+	}
+
+	if (val < 0 || val > 5) {
+		dev_err(dev, "invalid pulses-per-revolution %d of %pOFn\n", val, child);
+		return -EINVAL;
+	}
+	data->ppr[i] = val;
+
+	err = of_property_read_u32(child, "max-rpm", &maxrpm);
+	if (err) {
+		dev_err(dev, "missing max-rpm property of %pOFn\n", child);
+		return err;
+	}
+
+	err = rpm_range_to_index(dev, &data->rpm_range[i], maxrpm);
+	if (err) {
+		dev_err(dev, "invalid max-rpm %d of %pOFn\n", maxrpm, child);
+		return err;
+	}
+
+
+	err = of_property_read_u32(child, "target-rpm", &val);
+	/* Convert to PWM from provided target RPM */
+	if (!err && val != 0)
+		data->pwm[i] =
+			(u8)(val * 120 / maxrpm);
+
+	data->pwm_polarity[i] =  of_property_read_bool(child, "pwm-polarity-inverse");
+
+	return 0;
+}
+static int max6639_probe_from_dt(struct i2c_client *client, struct max6639_data *data)
+{
+	struct device *dev = &client->dev;
+	const struct device_node *np = dev->of_node;
+	struct device_node *child;
+	int err;
+
+	/* Compatible with non-DT platforms */
+	if (!np)
+		return 0;
+
+	for_each_child_of_node(np, child) {
+		if (strcmp(child->name, "fan"))
+			continue;
+
+		err = max6639_probe_child_from_dt(client, child, data);
+		if (err) {
+			of_node_put(child);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
 static int max6639_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	struct max6639_data *data;
 	struct device *hwmon_dev;
-	int err;
+	int err, i;
 
 	data = devm_kzalloc(dev, sizeof(struct max6639_data), GFP_KERNEL);
 	if (!data)
@@ -539,9 +607,11 @@ static int max6639_probe(struct i2c_client *client)
 
 	data->reg = devm_regulator_get_optional(dev, "fan");
 	if (IS_ERR(data->reg)) {
-		if (PTR_ERR(data->reg) != -ENODEV)
-			return PTR_ERR(data->reg);
-
+		if (PTR_ERR(data->reg) != -ENODEV) {
+			err = (int)PTR_ERR(data->reg);
+			dev_warn(dev, "Failed looking up fan supply: %d\n", err);
+			return err;
+		}
 		data->reg = NULL;
 	} else {
 		/* Spin up fans */
@@ -560,6 +630,24 @@ static int max6639_probe(struct i2c_client *client)
 
 	mutex_init(&data->update_lock);
 
+	/* default values */
+	for (i = 0; i < 2; i++) {
+		/* 4000 RPM */
+		data->rpm_range[i] = 1;
+		data->ppr[i] = 2;
+		data->pwm_polarity[i] = 1;
+		/* Max. temp. 80C/90C/100C */
+		data->temp_therm[i] = 80;
+		data->temp_alert[i] = 90;
+		data->temp_ot[i] = 100;
+		/* PWM 120/120 (i.e. 100%) */
+		data->pwm[i] = 120;
+	}
+
+	err = max6639_probe_from_dt(client, data);
+	if (err)
+		return err;
+
 	/* Initialize the max6639 chip */
 	err = max6639_init_client(client, data);
 	if (err < 0)
@@ -571,6 +659,7 @@ static int max6639_probe(struct i2c_client *client)
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }
 
+#if IS_ENABLED(CONFIG_PM_SLEEP)
 static int max6639_suspend(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
@@ -608,6 +697,7 @@ static int max6639_resume(struct device *dev)
 	return i2c_smbus_write_byte_data(client,
 			MAX6639_REG_GCONFIG, ret & ~MAX6639_GCONFIG_STANDBY);
 }
+#endif
 
 static const struct i2c_device_id max6639_id[] = {
 	{"max6639", 0},
@@ -616,13 +706,22 @@ static const struct i2c_device_id max6639_id[] = {
 
 MODULE_DEVICE_TABLE(i2c, max6639_id);
 
-static DEFINE_SIMPLE_DEV_PM_OPS(max6639_pm_ops, max6639_suspend, max6639_resume);
+#ifdef CONFIG_OF
+static const struct of_device_id maxim_of_platform_match[] = {
+	{.compatible = "maxim,max6639"},
+	{},
+};
+MODULE_DEVICE_TABLE(of, maxim_of_platform_match);
+#endif
+
+static SIMPLE_DEV_PM_OPS(max6639_pm_ops, max6639_suspend, max6639_resume);
 
 static struct i2c_driver max6639_driver = {
 	.class = I2C_CLASS_HWMON,
 	.driver = {
 		   .name = "max6639",
 		   .pm = pm_sleep_ptr(&max6639_pm_ops),
+		   .of_match_table = of_match_ptr(maxim_of_platform_match),
 		   },
 	.probe_new = max6639_probe,
 	.id_table = max6639_id,
-- 
2.37.3

Re: [PATCH v3 3/3] hwmon: (max6639) Change from pdata to dt configuration

[Guenter Roeck]

On 10/12/22 13:57, Naresh Solanki wrote:
> max6639_platform_data is not used by any in-kernel driver and does not
> address the MAX6639 fans separately.
> Move to device tree configuration with explicit properties to configure
> each fan.
> 
> Non-DT platform can still use this module with its default
> configuration.
> 
> Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>
> ---
>   drivers/hwmon/max6639.c | 205 +++++++++++++++++++++++++++++-----------
>   1 file changed, 152 insertions(+), 53 deletions(-)
> 
> diff --git a/drivers/hwmon/max6639.c b/drivers/hwmon/max6639.c
> index 9b895402c80d..2fc096a00e21 100644
> --- a/drivers/hwmon/max6639.c
> +++ b/drivers/hwmon/max6639.c
> @@ -19,7 +19,6 @@
>   #include <linux/hwmon-sysfs.h>
>   #include <linux/err.h>
>   #include <linux/mutex.h>
> -#include <linux/platform_data/max6639.h>
>   
>   /* Addresses to scan */
>   static const unsigned short normal_i2c[] = { 0x2c, 0x2e, 0x2f, I2C_CLIENT_END };
> @@ -85,9 +84,9 @@ struct max6639_data {
>   	u8 temp_ot[2];		/* OT Temperature, 0..255 C (->_emergency) */
>   
>   	/* Register values initialized only once */
> -	u8 ppr;			/* Pulses per rotation 0..3 for 1..4 ppr */
> -	u8 rpm_range;		/* Index in above rpm_ranges table */
> -
> +	u8 ppr[2];		/* Pulses per rotation 0..3 for 1..4 ppr */
> +	u8 rpm_range[2];	/* Index in above rpm_ranges table */
> +	u8 pwm_polarity[2];	/* Fans PWM polarity, 0..1 */
>   	/* Optional regulator for FAN supply */
>   	struct regulator *reg;
>   };
> @@ -319,7 +318,7 @@ static ssize_t fan_input_show(struct device *dev,
>   		return PTR_ERR(data);
>   
>   	return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan[attr->index],
> -		       data->rpm_range));
> +		       data->rpm_range[attr->index]));
>   }
>   
>   static ssize_t alarm_show(struct device *dev,
> @@ -386,29 +385,39 @@ static struct attribute *max6639_attrs[] = {
>   ATTRIBUTE_GROUPS(max6639);
>   
>   /*
> - *  returns respective index in rpm_ranges table
> - *  1 by default on invalid range
> + *  Get respective index in rpm_ranges table
>    */
> -static int rpm_range_to_reg(int range)
> +static int rpm_range_to_index(struct device *dev, u8 *index, int rpm)
>   {
> -	int i;
> -
> -	for (i = 0; i < ARRAY_SIZE(rpm_ranges); i++) {
> -		if (rpm_ranges[i] == range)
> -			return i;
> +	if (rpm < 0)
> +		return -EINVAL;
> +
> +	/* Set index based on chip support */
> +	switch (rpm) {
> +	case 0 ... 2000:
> +		*index = 0;
> +		break;
> +	case 2001 ... 4000:
> +		*index = 1;
> +		break;
> +	case 4001 ... 8000:
> +		*index = 2;
> +		break;
> +	case 8001 ... 16000:
> +		*index = 3;
> +		break;
> +	default:
> +		/* Use max range for higher RPM */
> +		dev_warn(dev, "RPM higher than supported range.");

It is illogical to complain about that but not about other invalid values.

> +		*index = 3;
>   	}
> -
> -	return 1; /* default: 4000 RPM */
> +	return 0;

The return value can be used both as error indicator (return value < 0)
and index (return value >= 0). It is not necessary to introduce a pointer.

>   }
>   
>   static int max6639_init_client(struct i2c_client *client,
>   			       struct max6639_data *data)
>   {
> -	struct max6639_platform_data *max6639_info =
> -		dev_get_platdata(&client->dev);
> -	int i;
> -	int rpm_range = 1; /* default: 4000 RPM */
> -	int err;
> +	int i, err;
>   
>   	/* Reset chip to default values, see below for GCONFIG setup */
>   	err = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
> @@ -416,51 +425,32 @@ static int max6639_init_client(struct i2c_client *client,
>   	if (err)
>   		goto exit;
>   
> -	/* Fans pulse per revolution is 2 by default */
> -	if (max6639_info && max6639_info->ppr > 0 &&
> -			max6639_info->ppr < 5)
> -		data->ppr = max6639_info->ppr;
> -	else
> -		data->ppr = 2;
> -	data->ppr -= 1;
> -
> -	if (max6639_info)
> -		rpm_range = rpm_range_to_reg(max6639_info->rpm_range);
> -	data->rpm_range = rpm_range;
> -
>   	for (i = 0; i < 2; i++) {
>   
>   		/* Set Fan pulse per revolution */
>   		err = i2c_smbus_write_byte_data(client,
>   				MAX6639_REG_FAN_PPR(i),
> -				data->ppr << 6);
> +				data->ppr[i] << 6);
>   		if (err)
>   			goto exit;
>   
>   		/* Fans config PWM, RPM */
>   		err = i2c_smbus_write_byte_data(client,
>   			MAX6639_REG_FAN_CONFIG1(i),
> -			MAX6639_FAN_CONFIG1_PWM | rpm_range);
> +			MAX6639_FAN_CONFIG1_PWM | data->rpm_range[i]);
>   		if (err)
>   			goto exit;
>   
> -		/* Fans PWM polarity high by default */
> -		if (max6639_info && max6639_info->pwm_polarity == 0)
> -			err = i2c_smbus_write_byte_data(client,
> -				MAX6639_REG_FAN_CONFIG2a(i), 0x00);
> -		else
> -			err = i2c_smbus_write_byte_data(client,
> -				MAX6639_REG_FAN_CONFIG2a(i), 0x02);
> -		if (err)
> -			goto exit;
> +		/* Fans PWM polarity */
> +		err = i2c_smbus_write_byte_data(client,
> +			MAX6639_REG_FAN_CONFIG2a(i), data->pwm_polarity[i] ? 0x02 : 0x00);
>   
>   		/*
> -		 * /THERM full speed enable,
> +		 * /THERM full speed disable,
>   		 * PWM frequency 25kHz, see also GCONFIG below
>   		 */
>   		err = i2c_smbus_write_byte_data(client,
> -			MAX6639_REG_FAN_CONFIG3(i),
> -			MAX6639_FAN_CONFIG3_THERM_FULL_SPEED | 0x03);
> +			MAX6639_REG_FAN_CONFIG3(i), 0x03);
>   		if (err)
>   			goto exit;
>   
> @@ -483,8 +473,6 @@ static int max6639_init_client(struct i2c_client *client,
>   		if (err)
>   			goto exit;
>   
> -		/* PWM 120/120 (i.e. 100%) */
> -		data->pwm[i] = 120;
>   		err = i2c_smbus_write_byte_data(client,
>   				MAX6639_REG_TARGTDUTY(i), data->pwm[i]);
>   		if (err)
> @@ -524,12 +512,92 @@ static void max6639_regulator_disable(void *data)
>   	regulator_disable(data);
>   }
>   
> +static int max6639_probe_child_from_dt(struct i2c_client *client,
> +				      struct device_node *child,
> +				      struct max6639_data *data)
> +
> +{
> +	struct device *dev = &client->dev;
> +	u32 i, val, maxrpm;
> +	int err;
> +
> +	err = of_property_read_u32(child, "reg", &i);
> +	if (err) {
> +		dev_err(dev, "missing reg property of %pOFn\n", child);
> +		return err;
> +	}
> +
> +	if (i >= 2) {
> +		dev_err(dev, "invalid reg %d of %pOFn\n", i, child);
> +		return -EINVAL;
> +	}
> +
> +	err = of_property_read_u32(child, "pulses-per-revolution", &val);
> +	if (err) {
> +		dev_err(dev, "missing pulses-per-revolution property of %pOFn\n", child);
> +		return err;
> +	}
> +
> +	if (val < 0 || val > 5) {
> +		dev_err(dev, "invalid pulses-per-revolution %d of %pOFn\n", val, child);
> +		return -EINVAL;
> +	}
> +	data->ppr[i] = val;
> +
> +	err = of_property_read_u32(child, "max-rpm", &maxrpm);
> +	if (err) {
> +		dev_err(dev, "missing max-rpm property of %pOFn\n", child);
> +		return err;
> +	}
> +
> +	err = rpm_range_to_index(dev, &data->rpm_range[i], maxrpm);
> +	if (err) {
> +		dev_err(dev, "invalid max-rpm %d of %pOFn\n", maxrpm, child);
> +		return err;
> +	}
> +
> +
Dual empty line.

> +	err = of_property_read_u32(child, "target-rpm", &val);
> +	/* Convert to PWM from provided target RPM */
> +	if (!err && val != 0)
> +		data->pwm[i] =
> +			(u8)(val * 120 / maxrpm);
> +

It is not acceptable for any of those missing properties to result
in errors. Use current chip values as default if values are not
provided.

> +	data->pwm_polarity[i] =  of_property_read_bool(child, "pwm-polarity-inverse");
> +
> +	return 0;
> +}
> +static int max6639_probe_from_dt(struct i2c_client *client, struct max6639_data *data)
> +{
> +	struct device *dev = &client->dev;
> +	const struct device_node *np = dev->of_node;
> +	struct device_node *child;
> +	int err;
> +
> +	/* Compatible with non-DT platforms */
> +	if (!np)
> +		return 0;
> +
> +	for_each_child_of_node(np, child) {
> +		if (strcmp(child->name, "fan"))
> +			continue;
> +
> +		err = max6639_probe_child_from_dt(client, child, data);
> +		if (err) {
> +			of_node_put(child);
> +			return err;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>   static int max6639_probe(struct i2c_client *client)
>   {
>   	struct device *dev = &client->dev;
>   	struct max6639_data *data;
>   	struct device *hwmon_dev;
> -	int err;
> +	int err, i;
>   
>   	data = devm_kzalloc(dev, sizeof(struct max6639_data), GFP_KERNEL);
>   	if (!data)
> @@ -539,9 +607,11 @@ static int max6639_probe(struct i2c_client *client)
>   
>   	data->reg = devm_regulator_get_optional(dev, "fan");
>   	if (IS_ERR(data->reg)) {
> -		if (PTR_ERR(data->reg) != -ENODEV)
> -			return PTR_ERR(data->reg);
> -
> +		if (PTR_ERR(data->reg) != -ENODEV) {
> +			err = (int)PTR_ERR(data->reg);
> +			dev_warn(dev, "Failed looking up fan supply: %d\n", err);

This is an unrelated change. It is not common to issue a warning
in that situation, and I am not inclined to accept it. Besides,
the function can return -EPROBE_DEFER, and any messages associated
with that are unacceptable.

> +			return err;
> +		}
>   		data->reg = NULL;
>   	} else {
>   		/* Spin up fans */
> @@ -560,6 +630,24 @@ static int max6639_probe(struct i2c_client *client)
>   
>   	mutex_init(&data->update_lock);
>   
> +	/* default values */
> +	for (i = 0; i < 2; i++) {
> +		/* 4000 RPM */
> +		data->rpm_range[i] = 1;
> +		data->ppr[i] = 2;
> +		data->pwm_polarity[i] = 1;
> +		/* Max. temp. 80C/90C/100C */
> +		data->temp_therm[i] = 80;
> +		data->temp_alert[i] = 90;
> +		data->temp_ot[i] = 100;
> +		/* PWM 120/120 (i.e. 100%) */
> +		data->pwm[i] = 120;
> +	}

As I said, defaults are values currently programmed into the chip,
not some random values.

> +
> +	err = max6639_probe_from_dt(client, data);
> +	if (err)
> +		return err;
> +
>   	/* Initialize the max6639 chip */
>   	err = max6639_init_client(client, data);
>   	if (err < 0)
> @@ -571,6 +659,7 @@ static int max6639_probe(struct i2c_client *client)
>   	return PTR_ERR_OR_ZERO(hwmon_dev);
>   }
>   
> +#if IS_ENABLED(CONFIG_PM_SLEEP)
>   static int max6639_suspend(struct device *dev)
>   {
>   	struct i2c_client *client = to_i2c_client(dev);
> @@ -608,6 +697,7 @@ static int max6639_resume(struct device *dev)
>   	return i2c_smbus_write_byte_data(client,
>   			MAX6639_REG_GCONFIG, ret & ~MAX6639_GCONFIG_STANDBY);
>   }
> +#endif

This can be done without #ifdef.
>   
>   static const struct i2c_device_id max6639_id[] = {
>   	{"max6639", 0},
> @@ -616,13 +706,22 @@ static const struct i2c_device_id max6639_id[] = {
>   
>   MODULE_DEVICE_TABLE(i2c, max6639_id);
>   
> -static DEFINE_SIMPLE_DEV_PM_OPS(max6639_pm_ops, max6639_suspend, max6639_resume);
> +#ifdef CONFIG_OF
> +static const struct of_device_id maxim_of_platform_match[] = {
> +	{.compatible = "maxim,max6639"},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, maxim_of_platform_match);
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(max6639_pm_ops, max6639_suspend, max6639_resume);
>   
>   static struct i2c_driver max6639_driver = {
>   	.class = I2C_CLASS_HWMON,
>   	.driver = {
>   		   .name = "max6639",
>   		   .pm = pm_sleep_ptr(&max6639_pm_ops),
> +		   .of_match_table = of_match_ptr(maxim_of_platform_match),
>   		   },
>   	.probe_new = max6639_probe,
>   	.id_table = max6639_id,