[v8,1/2] dt-bindings: hwmon: Add nct7802 bindings

This change documents the device tree bindings for the Nuvoton
NCT7802Y driver.

Signed-off-by: Oskar Senft <osk@google.com>
---
Changes from PATCH v7:
- Implemented review comments:
  - Added blank lines to increase readability.
  - Moved "additionalProperties" up to increase readability.

Changes from PATCH v6:
- Fixed formatting error reported by yamllint

Changes from PATCH v5:
- Refactored to use patternProperties.
- Added validation for sensor-type and temperature-mode.
---
 .../bindings/hwmon/nuvoton,nct7802.yaml       | 145 ++++++++++++++++++
 1 file changed, 145 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/nuvoton,nct7802.yaml

On Wed, 20 Oct 2021 12:42:12 -0400, Oskar Senft wrote:
> This change documents the device tree bindings for the Nuvoton
> NCT7802Y driver.
> 
> Signed-off-by: Oskar Senft <osk@google.com>
> ---
> Changes from PATCH v7:
> - Implemented review comments:
>   - Added blank lines to increase readability.
>   - Moved "additionalProperties" up to increase readability.
> 
> Changes from PATCH v6:
> - Fixed formatting error reported by yamllint
> 
> Changes from PATCH v5:
> - Refactored to use patternProperties.
> - Added validation for sensor-type and temperature-mode.
> ---
>  .../bindings/hwmon/nuvoton,nct7802.yaml       | 145 ++++++++++++++++++
>  1 file changed, 145 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/nuvoton,nct7802.yaml
> 

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

On Wed, Oct 20, 2021 at 12:42:12PM -0400, Oskar Senft wrote:
> This change documents the device tree bindings for the Nuvoton
> NCT7802Y driver.
> 
> Signed-off-by: Oskar Senft <osk@google.com>
> Reviewed-by: Rob Herring <robh@kernel.org>

Applied.

Thanks,
Guenter

> ---
> Changes from PATCH v7:
> - Implemented review comments:
>   - Added blank lines to increase readability.
>   - Moved "additionalProperties" up to increase readability.
> 
> Changes from PATCH v6:
> - Fixed formatting error reported by yamllint
> 
> Changes from PATCH v5:
> - Refactored to use patternProperties.
> - Added validation for sensor-type and temperature-mode.
> ---
>  .../bindings/hwmon/nuvoton,nct7802.yaml       | 145 ++++++++++++++++++
>  1 file changed, 145 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/nuvoton,nct7802.yaml
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/nuvoton,nct7802.yaml b/Documentation/devicetree/bindings/hwmon/nuvoton,nct7802.yaml
> new file mode 100644
> index 000000000000..2f0620ecccc9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/nuvoton,nct7802.yaml
> @@ -0,0 +1,145 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +
> +$id: http://devicetree.org/schemas/hwmon/nuvoton,nct7802.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Nuvoton NCT7802Y Hardware Monitoring IC
> +
> +maintainers:
> +  - Guenter Roeck <linux@roeck-us.net>
> +
> +description: |
> +  The NCT7802Y is a hardware monitor IC which supports one on-die and up to
> +  5 remote temperature sensors with SMBus interface.
> +
> +  Datasheets:
> +    https://www.nuvoton.com/export/resource-files/Nuvoton_NCT7802Y_Datasheet_V12.pdf
> +
> +additionalProperties: false
> +
> +properties:
> +  compatible:
> +    enum:
> +      - nuvoton,nct7802
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 0
> +
> +patternProperties:
> +  "^channel@[0-3]$":
> +    type: object
> +
> +    additionalProperties: false
> +
> +    properties:
> +      reg:
> +        items:
> +          - enum:
> +              - 0    # Local Temperature Sensor ("LTD")
> +              - 1    # Remote Temperature Sensor or Voltage Sensor 1 ("RTD1")
> +              - 2    # Remote Temperature Sensor or Voltage Sensor 2 ("RTD2")
> +              - 3    # Remote Temperature Sensor or Voltage Sensor 3 ("RTD3")
> +
> +      sensor-type:
> +        items:
> +          - enum:
> +              - temperature
> +              - voltage
> +
> +      temperature-mode:
> +        items:
> +          - enum:
> +              - thermistor
> +              - thermal-diode
> +
> +    required:
> +      - reg
> +
> +    allOf:
> +      # For channels RTD1, RTD2 and RTD3, require sensor-type to be set.
> +      # Otherwise (for all other channels), do not allow temperature-mode to be
> +      # set.
> +      - if:
> +          properties:
> +            reg:
> +              items:
> +                - enum:
> +                    - 1
> +                    - 2
> +                    - 3
> +        then:
> +          required:
> +            - sensor-type
> +        else:
> +          not:
> +            required:
> +              - sensor-type
> +
> +      # For channels RTD1 and RTD2 and if sensor-type is "temperature", require
> +      # temperature-mode to be set. Otherwise (for all other channels or
> +      # sensor-type settings), do not allow temperature-mode to be set
> +      - if:
> +          properties:
> +            reg:
> +              items:
> +                - enum:
> +                    - 1
> +                    - 2
> +            sensor-type:
> +              items:
> +                - enum:
> +                    - temperature
> +        then:
> +          required:
> +            - temperature-mode
> +        else:
> +          not:
> +            required:
> +              - temperature-mode
> +
> +required:
> +  - compatible
> +  - reg
> +
> +examples:
> +  - |
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        nct7802@28 {
> +            compatible = "nuvoton,nct7802";
> +            reg = <0x28>;
> +
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            channel@0 { /* LTD */
> +              reg = <0>;
> +            };
> +
> +            channel@1 { /* RTD1 */
> +              reg = <1>;
> +              sensor-type = "voltage";
> +            };
> +
> +            channel@2 { /* RTD2 */
> +              reg = <2>;
> +              sensor-type = "temperature";
> +              temperature-mode = "thermal-diode";
> +            };
> +
> +            channel@3 { /* RTD3 */
> +              reg = <3>;
> +              sensor-type = "temperature";
> +            };
> +        };
> +    };

On Wed, Oct 20, 2021 at 12:42:13PM -0400, Oskar Senft wrote:
> This change allows LTD and RTD inputs to be configured via
> device tree bindings. If the DT bindings are not present or
> invalid, the input configuration is not modified and left at
> HW defaults.
> 
> Signed-off-by: Oskar Senft <osk@google.com>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Applied.

Thanks,
Guenter

> ---
> Changes from PATCH v6 and v7:
> - None (resubmitted due to changes in nuvoton,nct7802.yaml).
> 
> Changes from PATCH v5:
> - Removed unused "found_channel_config" variable.
> - Initialize mode_mask and mode_val to defaults.
> ---
>  drivers/hwmon/nct7802.c | 129 ++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 125 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hwmon/nct7802.c b/drivers/hwmon/nct7802.c
> index 604af2f6103a..d56f78327619 100644
> --- a/drivers/hwmon/nct7802.c
> +++ b/drivers/hwmon/nct7802.c
> @@ -51,6 +51,23 @@ static const u8 REG_VOLTAGE_LIMIT_MSB_SHIFT[2][5] = {
>  #define REG_CHIP_ID		0xfe
>  #define REG_VERSION_ID		0xff
>  
> +/*
> + * Resistance temperature detector (RTD) modes according to 7.2.32 Mode
> + * Selection Register
> + */
> +#define RTD_MODE_CURRENT	0x1
> +#define RTD_MODE_THERMISTOR	0x2
> +#define RTD_MODE_VOLTAGE	0x3
> +
> +#define MODE_RTD_MASK		0x3
> +#define MODE_LTD_EN		0x40
> +
> +/*
> + * Bit offset for sensors modes in REG_MODE.
> + * Valid for index 0..2, indicating RTD1..3.
> + */
> +#define MODE_BIT_OFFSET_RTD(index) ((index) * 2)
> +
>  /*
>   * Data structures and manipulation thereof
>   */
> @@ -1038,7 +1055,112 @@ static const struct regmap_config nct7802_regmap_config = {
>  	.volatile_reg = nct7802_regmap_is_volatile,
>  };
>  
> -static int nct7802_init_chip(struct nct7802_data *data)
> +static int nct7802_get_channel_config(struct device *dev,
> +				      struct device_node *node, u8 *mode_mask,
> +				      u8 *mode_val)
> +{
> +	u32 reg;
> +	const char *type_str, *md_str;
> +	u8 md;
> +
> +	if (!node->name || of_node_cmp(node->name, "channel"))
> +		return 0;
> +
> +	if (of_property_read_u32(node, "reg", &reg)) {
> +		dev_err(dev, "Could not read reg value for '%s'\n",
> +			node->full_name);
> +		return -EINVAL;
> +	}
> +
> +	if (reg > 3) {
> +		dev_err(dev, "Invalid reg (%u) in '%s'\n", reg,
> +			node->full_name);
> +		return -EINVAL;
> +	}
> +
> +	if (reg == 0) {
> +		if (!of_device_is_available(node))
> +			*mode_val &= ~MODE_LTD_EN;
> +		else
> +			*mode_val |= MODE_LTD_EN;
> +		*mode_mask |= MODE_LTD_EN;
> +		return 0;
> +	}
> +
> +	/* At this point we have reg >= 1 && reg <= 3 */
> +
> +	if (!of_device_is_available(node)) {
> +		*mode_val &= ~(MODE_RTD_MASK << MODE_BIT_OFFSET_RTD(reg - 1));
> +		*mode_mask |= MODE_RTD_MASK << MODE_BIT_OFFSET_RTD(reg - 1);
> +		return 0;
> +	}
> +
> +	if (of_property_read_string(node, "sensor-type", &type_str)) {
> +		dev_err(dev, "No type for '%s'\n", node->full_name);
> +		return -EINVAL;
> +	}
> +
> +	if (!strcmp(type_str, "voltage")) {
> +		*mode_val |= (RTD_MODE_VOLTAGE & MODE_RTD_MASK)
> +			     << MODE_BIT_OFFSET_RTD(reg - 1);
> +		*mode_mask |= MODE_RTD_MASK << MODE_BIT_OFFSET_RTD(reg - 1);
> +		return 0;
> +	}
> +
> +	if (strcmp(type_str, "temperature")) {
> +		dev_err(dev, "Invalid type '%s' for '%s'\n", type_str,
> +			node->full_name);
> +		return -EINVAL;
> +	}
> +
> +	if (reg == 3) {
> +		/* RTD3 only supports thermistor mode */
> +		md = RTD_MODE_THERMISTOR;
> +	} else {
> +		if (of_property_read_string(node, "temperature-mode",
> +					    &md_str)) {
> +			dev_err(dev, "No mode for '%s'\n", node->full_name);
> +			return -EINVAL;
> +		}
> +
> +		if (!strcmp(md_str, "thermal-diode"))
> +			md = RTD_MODE_CURRENT;
> +		else if (!strcmp(md_str, "thermistor"))
> +			md = RTD_MODE_THERMISTOR;
> +		else {
> +			dev_err(dev, "Invalid mode '%s' for '%s'\n", md_str,
> +				node->full_name);
> +			return -EINVAL;
> +		}
> +	}
> +
> +	*mode_val |= (md & MODE_RTD_MASK) << MODE_BIT_OFFSET_RTD(reg - 1);
> +	*mode_mask |= MODE_RTD_MASK << MODE_BIT_OFFSET_RTD(reg - 1);
> +
> +	return 0;
> +}
> +
> +static int nct7802_configure_channels(struct device *dev,
> +				      struct nct7802_data *data)
> +{
> +	/* Enable local temperature sensor by default */
> +	u8 mode_mask = MODE_LTD_EN, mode_val = MODE_LTD_EN;
> +	struct device_node *node;
> +	int err;
> +
> +	if (dev->of_node) {
> +		for_each_child_of_node(dev->of_node, node) {
> +			err = nct7802_get_channel_config(dev, node, &mode_mask,
> +							 &mode_val);
> +			if (err)
> +				return err;
> +		}
> +	}
> +
> +	return regmap_update_bits(data->regmap, REG_MODE, mode_mask, mode_val);
> +}
> +
> +static int nct7802_init_chip(struct device *dev, struct nct7802_data *data)
>  {
>  	int err;
>  
> @@ -1047,8 +1169,7 @@ static int nct7802_init_chip(struct nct7802_data *data)
>  	if (err)
>  		return err;
>  
> -	/* Enable local temperature sensor */
> -	err = regmap_update_bits(data->regmap, REG_MODE, 0x40, 0x40);
> +	err = nct7802_configure_channels(dev, data);
>  	if (err)
>  		return err;
>  
> @@ -1074,7 +1195,7 @@ static int nct7802_probe(struct i2c_client *client)
>  	mutex_init(&data->access_lock);
>  	mutex_init(&data->in_alarm_lock);
>  
> -	ret = nct7802_init_chip(data);
> +	ret = nct7802_init_chip(dev, data);
>  	if (ret < 0)
>  		return ret;
>