[PATCH 0/2] hwmon: (pmbus/lm25066) Support SMBus Current Limit configuration

[PATCH 0/2] hwmon: (pmbus/lm25066) Support SMBus Current Limit configuration

[Potin Lai]

This patch series adds support for configuring the Current Limit (CL)
behavior of the TI LM25066 and compatible devices (LM25056, LM5064,
LM5066, LM5066I) using SMBus settings instead of physical hardware pins.

The first patch documents the mutually exclusive Devicetree properties
'ti,cl-smbus-high' and 'ti,cl-smbus-low'.

The second patch implements the driver changes to configure the DEVICE_SETUP
(0xD9) register based on these DT properties. It handles the dynamic differences
in the CL bit (bit 4) mapping where LM25056 and LM25066 have swapped logic for
High/Low settings compared to LM5064, LM5066, and LM5066i.

Signed-off-by: Potin Lai <potin.lai.pt@gmail.com>
---
Potin Lai (2):
      dt-bindings: hwmon: pmbus: ti,lm25066: add current limit properties
      hwmon: (pmbus/lm25066) add SMBus current limit configuration support

 .../bindings/hwmon/pmbus/ti,lm25066.yaml           | 20 +++++++++++++++++
 drivers/hwmon/pmbus/lm25066.c                      | 25 ++++++++++++++++++++++
 2 files changed, 45 insertions(+)
---
base-commit: 05f7e89ab9731565d8a62e3b5d1ec206485eeb0b
change-id: 20260611-lm25066-cl-config-f81925f7337e

Best regards,
--  
Potin Lai <potin.lai.pt@gmail.com>

[PATCH 1/2] dt-bindings: hwmon: pmbus: ti,lm25066: add current limit properties

[Potin Lai]

Add mutually exclusive 'ti,cl-smbus-high' and 'ti,cl-smbus-low' boolean
properties to configure the device's Current Limit (CL) behavior using
SMBus settings instead of physical pins.

Signed-off-by: Potin Lai <potin.lai.pt@gmail.com>
---
 .../devicetree/bindings/hwmon/pmbus/ti,lm25066.yaml  | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/devicetree/bindings/hwmon/pmbus/ti,lm25066.yaml b/Documentation/devicetree/bindings/hwmon/pmbus/ti,lm25066.yaml
index a20f140dc79a..95ea7c26dec2 100644
--- a/Documentation/devicetree/bindings/hwmon/pmbus/ti,lm25066.yaml
+++ b/Documentation/devicetree/bindings/hwmon/pmbus/ti,lm25066.yaml
@@ -46,6 +46,26 @@ properties:
 
     additionalProperties: false
 
+  ti,cl-smbus-high:
+    description: |
+      Configure the Current Limit (CL) to use the SMBus high setting.
+    type: boolean
+
+  ti,cl-smbus-low:
+    description: |
+      Configure the Current Limit (CL) to use the SMBus low setting.
+    type: boolean
+
+dependencies:
+  ti,cl-smbus-high:
+    not:
+      required:
+        - ti,cl-smbus-low
+  ti,cl-smbus-low:
+    not:
+      required:
+        - ti,cl-smbus-high
+
 required:
   - compatible
   - reg

-- 
2.52.0

Re: [PATCH 1/2] dt-bindings: hwmon: pmbus: ti,lm25066: add current limit properties

[sashiko-bot]

> Add mutually exclusive 'ti,cl-smbus-high' and 'ti,cl-smbus-low' boolean
> properties to configure the device's Current Limit (CL) behavior using
> SMBus settings instead of physical pins.
> 
> Signed-off-by: Potin Lai <potin.lai.pt@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260611-lm25066-cl-config-v1-0-02e567bf3d91@gmail.com?part=1

Re: [PATCH 1/2] dt-bindings: hwmon: pmbus: ti,lm25066: add current limit properties

[Conor Dooley]

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On Thu, Jun 11, 2026 at 05:58:44PM +0800, Potin Lai wrote:
> Add mutually exclusive 'ti,cl-smbus-high' and 'ti,cl-smbus-low' boolean
> properties to configure the device's Current Limit (CL) behavior using
> SMBus settings instead of physical pins.
> 
> Signed-off-by: Potin Lai <potin.lai.pt@gmail.com>
> ---
>  .../devicetree/bindings/hwmon/pmbus/ti,lm25066.yaml  | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/pmbus/ti,lm25066.yaml b/Documentation/devicetree/bindings/hwmon/pmbus/ti,lm25066.yaml
> index a20f140dc79a..95ea7c26dec2 100644
> --- a/Documentation/devicetree/bindings/hwmon/pmbus/ti,lm25066.yaml
> +++ b/Documentation/devicetree/bindings/hwmon/pmbus/ti,lm25066.yaml
> @@ -46,6 +46,26 @@ properties:
>  
>      additionalProperties: false
>  
> +  ti,cl-smbus-high:
> +    description: |
> +      Configure the Current Limit (CL) to use the SMBus high setting.
> +    type: boolean
> +
> +  ti,cl-smbus-low:
> +    description: |
> +      Configure the Current Limit (CL) to use the SMBus low setting.
> +    type: boolean

What's smbus specific about this? If the pin was connected to a GPIO,
you'd then need to have different properties or use these ones with an
inaccurate name.

Please also spell out "current-limit".

pw-bot: changes-requested

Thanks,
Conor.

> +
> +dependencies:
> +  ti,cl-smbus-high:
> +    not:
> +      required:
> +        - ti,cl-smbus-low
> +  ti,cl-smbus-low:
> +    not:
> +      required:
> +        - ti,cl-smbus-high
> +
>  required:
>    - compatible
>    - reg
> 
> -- 
> 2.52.0
> 

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[PATCH 2/2] hwmon: (pmbus/lm25066) add SMBus current limit configuration support

[Potin Lai]

Add support for the mutually exclusive 'ti,cl-smbus-high' and
'ti,cl-smbus-low' devicetree properties. When present, these properties
override the hardware configuration pins via the DEVICE_SETUP (0xD9)
register to set the Current Limit Configuration bit (bit 2) and
Current Limit Setting bit (bit 4) to SMBus settings.

The Bit 4 mapping to High/Low current limit is handled dynamically on
probe because it is swapped for lm25056 and lm25066 compared to other
supported chips (lm5064, lm5066, and lm5066i).

Signed-off-by: Potin Lai <potin.lai.pt@gmail.com>
---
 drivers/hwmon/pmbus/lm25066.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/hwmon/pmbus/lm25066.c b/drivers/hwmon/pmbus/lm25066.c
index dd7275a67a0a..20e114bdc882 100644
--- a/drivers/hwmon/pmbus/lm25066.c
+++ b/drivers/hwmon/pmbus/lm25066.c
@@ -34,6 +34,7 @@ enum chips { lm25056, lm25066, lm5064, lm5066, lm5066i };
 #define LM25066_READ_AVG_PIN		0xdf
 
 #define LM25066_DEV_SETUP_CL		BIT(4)	/* Current limit */
+#define LM25066_DEV_SETUP_CL_CFG	BIT(2)	/* Current limit configuration */
 
 #define LM25066_SAMPLES_FOR_AVG_MAX	4096
 
@@ -464,6 +465,8 @@ MODULE_DEVICE_TABLE(of, lm25066_of_match);
 static int lm25066_probe(struct i2c_client *client)
 {
 	int config;
+	int config_new;
+	int ret;
 	u32 shunt;
 	struct lm25066_data *data;
 	struct pmbus_driver_info *info;
@@ -484,6 +487,28 @@ static int lm25066_probe(struct i2c_client *client)
 
 	data->id = (enum chips)(unsigned long)i2c_get_match_data(client);
 
+	config_new = config;
+	if (of_property_read_bool(client->dev.of_node, "ti,cl-smbus-high")) {
+		config_new |= LM25066_DEV_SETUP_CL_CFG;
+		if (data->id == lm25056 || data->id == lm25066)
+			config_new |= LM25066_DEV_SETUP_CL;
+		else
+			config_new &= ~LM25066_DEV_SETUP_CL;
+	} else if (of_property_read_bool(client->dev.of_node, "ti,cl-smbus-low")) {
+		config_new |= LM25066_DEV_SETUP_CL_CFG;
+		if (data->id == lm25056 || data->id == lm25066)
+			config_new &= ~LM25066_DEV_SETUP_CL;
+		else
+			config_new |= LM25066_DEV_SETUP_CL;
+	}
+
+	if (config_new != config) {
+		ret = i2c_smbus_write_byte_data(client, LM25066_DEVICE_SETUP, config_new);
+		if (ret < 0)
+			return ret;
+		config = config_new;
+	}
+
 	info = &data->info;
 
 	info->pages = 1;

-- 
2.52.0

Re: [PATCH 2/2] hwmon: (pmbus/lm25066) add SMBus current limit configuration support

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] The driver incorrectly scales current and power telemetry for LM5064/LM5066/LM5066i chips by a factor of 2 because it fails to account for a swapped hardware bit mapping when selecting PMBus coefficients.
--

commit c83de5ba055b8d019bcdbf2292f57ea088b2924b
Author: Potin Lai <potin.lai.pt@gmail.com>

hwmon: (pmbus/lm25066) add SMBus current limit configuration support

This commit adds support for the 'ti,cl-smbus-high' and 'ti,cl-smbus-low'
devicetree properties to configure the current limit via SMBus. It sets
the Current Limit Configuration and Current Limit Setting bits, accounting
for swapped bit mapping on certain chips.

> diff --git a/drivers/hwmon/pmbus/lm25066.c b/drivers/hwmon/pmbus/lm25066.c
> index dd7275a67a0ab..20e114bdc882d 100644
> --- a/drivers/hwmon/pmbus/lm25066.c
> +++ b/drivers/hwmon/pmbus/lm25066.c
> @@ -464,6 +465,8 @@ MODULE_DEVICE_TABLE(of, lm25066_of_match);
>  static int lm25066_probe(struct i2c_client *client)
>  {
>  	int config;
> +	int config_new;
> +	int ret;
>  	u32 shunt;
>  	struct lm25066_data *data;
>  	struct pmbus_driver_info *info;

[ ... ]

> @@ -484,6 +487,28 @@ static int lm25066_probe(struct i2c_client *client)
>  
>  	data->id = (enum chips)(unsigned long)i2c_get_match_data(client);
>  
> +	config_new = config;
> +	if (of_property_read_bool(client->dev.of_node, "ti,cl-smbus-high")) {
> +		config_new |= LM25066_DEV_SETUP_CL_CFG;
> +		if (data->id == lm25056 || data->id == lm25066)
> +			config_new |= LM25066_DEV_SETUP_CL;
> +		else
> +			config_new &= ~LM25066_DEV_SETUP_CL;
> +	} else if (of_property_read_bool(client->dev.of_node, "ti,cl-smbus-low")) {
> +		config_new |= LM25066_DEV_SETUP_CL_CFG;
> +		if (data->id == lm25056 || data->id == lm25066)
> +			config_new &= ~LM25066_DEV_SETUP_CL;
> +		else
> +			config_new |= LM25066_DEV_SETUP_CL;
> +	}
> +
> +	if (config_new != config) {
> +		ret = i2c_smbus_write_byte_data(client, LM25066_DEVICE_SETUP, config_new);
> +		if (ret < 0)
> +			return ret;
> +		config = config_new;
> +	}
> +

[Severity: High]
This is a pre-existing issue, but does this patch leave the new explicit
device tree configuration feature broken for some chips?

The new code correctly identifies that the DEVICE_SETUP Current Limit bit
(Bit 4) mapping is swapped between the LM25056/LM25066 chips (1 = High
limit) and LM5064/LM5066/LM5066i chips (0 = High limit).

However, further down in lm25066_probe(), the coefficient selection logic
fails to account for this chip-specific swap:

    if (config & LM25066_DEV_SETUP_CL) {
        info->m[PSC_CURRENT_IN] = coeff[PSC_CURRENT_IN_L].m;
        info->b[PSC_CURRENT_IN] = coeff[PSC_CURRENT_IN_L].b;
        ...
    } else {
        info->m[PSC_CURRENT_IN] = coeff[PSC_CURRENT_IN].m;
        info->b[PSC_CURRENT_IN] = coeff[PSC_CURRENT_IN].b;
        ...
    }

When an LM5066 is configured to the high limit via ti,cl-smbus-high, the
driver clears Bit 4. The coefficient logic then sees Bit 4 is 0 and
incorrectly selects the PSC_CURRENT_IN (Low limit) coefficients.

Could this cause the calculated current and power telemetry for the LM5064,
LM5066, and LM5066i chips to be under-reported by roughly 2x?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260611-lm25066-cl-config-v1-0-02e567bf3d91@gmail.com?part=2

Re: [PATCH 2/2] hwmon: (pmbus/lm25066) add SMBus current limit configuration support

[Guenter Roeck]

On 6/11/26 02:58, Potin Lai wrote:
> Add support for the mutually exclusive 'ti,cl-smbus-high' and
> 'ti,cl-smbus-low' devicetree properties. When present, these properties
> override the hardware configuration pins via the DEVICE_SETUP (0xD9)
> register to set the Current Limit Configuration bit (bit 2) and
> Current Limit Setting bit (bit 4) to SMBus settings.
> 
> The Bit 4 mapping to High/Low current limit is handled dynamically on
> probe because it is swapped for lm25056 and lm25066 compared to other
> supported chips (lm5064, lm5066, and lm5066i).
> 
> Signed-off-by: Potin Lai <potin.lai.pt@gmail.com>
> ---
>   drivers/hwmon/pmbus/lm25066.c | 25 +++++++++++++++++++++++++
>   1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/hwmon/pmbus/lm25066.c b/drivers/hwmon/pmbus/lm25066.c
> index dd7275a67a0a..20e114bdc882 100644
> --- a/drivers/hwmon/pmbus/lm25066.c
> +++ b/drivers/hwmon/pmbus/lm25066.c
> @@ -34,6 +34,7 @@ enum chips { lm25056, lm25066, lm5064, lm5066, lm5066i };
>   #define LM25066_READ_AVG_PIN		0xdf
>   
>   #define LM25066_DEV_SETUP_CL		BIT(4)	/* Current limit */
> +#define LM25066_DEV_SETUP_CL_CFG	BIT(2)	/* Current limit configuration */
>   
>   #define LM25066_SAMPLES_FOR_AVG_MAX	4096
>   
> @@ -464,6 +465,8 @@ MODULE_DEVICE_TABLE(of, lm25066_of_match);
>   static int lm25066_probe(struct i2c_client *client)
>   {
>   	int config;
> +	int config_new;
> +	int ret;
>   	u32 shunt;
>   	struct lm25066_data *data;
>   	struct pmbus_driver_info *info;
> @@ -484,6 +487,28 @@ static int lm25066_probe(struct i2c_client *client)
>   
>   	data->id = (enum chips)(unsigned long)i2c_get_match_data(client);
>   
> +	config_new = config;
> +	if (of_property_read_bool(client->dev.of_node, "ti,cl-smbus-high")) {
> +		config_new |= LM25066_DEV_SETUP_CL_CFG;
> +		if (data->id == lm25056 || data->id == lm25066)

LM25056 does not support setting the gain via software, and bit 2 of this
register is reserved. These properties need to be disabled for that chip.
That will have to be reflected both here and in the devicetree file.

Thanks,
Guenter