Re: [PATCH 1/2] dt-bindings: i3c: add binding for Realtek RTS490x I3C HUB

[Frank Li <Frank.li@nxp.com>]

On Thu, Apr 30, 2026 at 08:13:53PM +0800, zain_zhou@realsil.com.cn wrote:
> From: zain_zhou <zain_zhou@realsil.com.cn>
>
> Add DT binding schema for Realtek RTS490x series I3C HUB devices.
>
> The binding describes configuration properties for:
>   - LDO enable/disable and voltage level per port group
>   - Pull-up resistance per port group
>   - IO driver strength per port
>   - Per target-port mode (I3C/SMBus/GPIO/disabled), pull-up,
>     IO mode, SMBus clock frequency and polling interval
>   - Hub network always-I3C mode
>   - Hardware identification via CSEL pin (id) and CP1 pins (id-cp1)

Please base on
https://lore.kernel.org/linux-i3c/20260420105222.1562243-1-lakshay.piplani@nxp.com/T/#t

which almost done!

Frank

>
> Signed-off-by: zain_zhou <zain_zhou@realsil.com.cn>
> ---
>  .../bindings/i3c/realtek,rts490x-i3c-hub.yaml | 410 ++++++++++++++++++
>  MAINTAINERS                                   |   6 +
>  2 files changed, 416 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/i3c/realtek,rts490x-i3c-hub.yaml
>
> diff --git a/Documentation/devicetree/bindings/i3c/realtek,rts490x-i3c-hub.yaml b/Documentation/devicetree/bindings/i3c/realtek,rts490x-i3c-hub.yaml
> new file mode 100644
> index 000000000000..30295eefee89
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i3c/realtek,rts490x-i3c-hub.yaml
> @@ -0,0 +1,410 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/i3c/realtek,rts490x-i3c-hub.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: I3C HUB
> +
> +maintainers:
> +  - zain_zhou <zain_zhou@realsil.com.cn>
> +
> +description: |
> +  I3C HUB is smart device which provides multiple functionality:
> +  * enabling voltage compatibility across I3C Controller and Target devices,
> +  * bus capacitance isolation
> +  * address conflict isolation
> +  * I3C port expansion
> +  * two controllers in a single I3C bus
> +  * I3C and SMBus device compatibility
> +  * GPIO expansion
> +
> +  Having such big number of features, there is a need to have some DT knobs to tell the I3C HUB
> +  driver which features shall be enabled and how they shall be configured. I3C HUB driver read,
> +  validate DT knobs and set corresponding registers with the right way to satisfy user requests from
> +  DT.
> +
> +  All the DT properties for I3C HUB are located under dedicated (for I3C HUB) DT entry. I3C HUB DT
> +  entry structure is aligned with regular I3C device DT entry described in i3c.yaml.
> +
> +allOf:
> +  - $ref: i3c.yaml#
> +
> +properties:
> +  $nodename:
> +    pattern: "^hub@0,0$"
> +
> +  cp0-ldo-en:
> +    enum:
> +      - disabled
> +      - enabled
> +    description: |
> +      I3C HUB Controller Port 0 LDO disabling/enabling setting. If enabled, voltage produced by
> +      on-die LDO will be available externally on dedicated pin. This option could be used to supply
> +      external pull-up resistors or for any other purpose which does not cross LDO capabilities.
> +
> +      This property is optional. If not provided, LDO will be disabled.
> +
> +  cp1-ldo-en:
> +    enum:
> +      - disabled
> +      - enabled
> +    description: |
> +      I3C HUB Controller Port 1 LDO disabling/enabling setting. If enabled, voltage produced by
> +      on-die LDO will be available externally on dedicated pin. This option could be used to supply
> +      external pull-up resistors or for any other purpose which does not cross LDO capabilities.
> +
> +      This property is optional. If not provided, LDO will be disabled.
> +
> +  tp0145-ldo-en:
> +    enum:
> +      - disabled
> +      - enabled
> +    description: |
> +      I3C HUB Target Ports 0/1/4/5 LDO disabling/enabling setting. If enabled, voltage produced by
> +      on-die LDO will be available externally on dedicated pin. This option could be used to supply
> +      external pull-up resistors or for any other purpose which does not cross LDO capabilities.
> +
> +      This property is optional. If not provided, LDO will be disabled.
> +
> +  tp2367-ldo-en:
> +    enum:
> +      - disabled
> +      - enabled
> +    description: |
> +      I3C HUB Target Ports 2/3/6/7 LDO disabling/enabling setting. If enabled, voltage produced by
> +      on-die LDO will be available externally on dedicated pin. This option could be used to supply
> +      external pull-up resistors or for any other purpose which does not cross LDO capabilities.
> +
> +      This property is optional. If not provided, LDO will be disabled.
> +
> +  cp0-ldo-volt:
> +    enum:
> +      - 1.0V
> +      - 1.1V
> +      - 1.2V
> +      - 1.8V
> +    description: |
> +      I3C HUB Controller Port 0 LDO setting to control the Controller Port 1 voltage level. This
> +      property is optional.
> +
> +      If not provided, LDO configuration is not modified in I3C HUB.
> +
> +  cp1-ldo-volt:
> +    enum:
> +      - 1.0V
> +      - 1.1V
> +      - 1.2V
> +      - 1.8V
> +    description: |
> +      I3C HUB Controller Port 1 LDO setting to control the Controller Port 1 voltage level. This
> +      property is optional.
> +
> +      If not provided, LDO configuration is not modified in I3C HUB.
> +
> +  tp0145-ldo-volt:
> +    enum:
> +      - disabled
> +      - 1.0V
> +      - 1.1V
> +      - 1.2V
> +      - 1.8V
> +    description: |
> +      I3C HUB Target Ports 0/1/4/5 LDO setting to control the Target Ports 0/1/4/5 voltage level.
> +
> +      If not provided, LDO configuration is not modified in I3C HUB.
> +
> +  tp2367-ldo-volt:
> +    enum:
> +      - disabled
> +      - 1.0V
> +      - 1.1V
> +      - 1.2V
> +      - 1.8V
> +    description: |
> +      I3C HUB Target Ports 2/3/6/7 LDO setting to control the Target Ports 2/3/6/7 voltage level.
> +
> +      If not provided, LDO configuration is not modified in I3C HUB.
> +
> +  tp0145-pullup:
> +    enum:
> +      - disabled
> +      - 250R
> +      - 500R
> +      - 1k
> +      - 2k
> +    description: |
> +      I3C HUB Target Ports 0/1/4/5 pull-up setting to control the Target Ports 0/1/4/5 pull-up
> +      resistance level.
> +
> +      This property is optional. If not provided, pull-up configuration is not modified in I3C HUB.
> +
> +  tp2367-pullup:
> +    enum:
> +      - disabled
> +      - 250R
> +      - 500R
> +      - 1k
> +      - 2k
> +    description: |
> +      I3C HUB Target Ports 2/3/6/7 pull-up setting to control the Target Ports 2/3/6/7 pull-up
> +      resistance level.
> +
> +      This property is optional. If not provided, pull-up configuration is not modified in I3C HUB.
> +
> +  cp0-io-strength:
> +    enum:
> +      - 20Ohms
> +      - 30Ohms
> +      - 40Ohms
> +      - 50Ohms
> +    description: |
> +      I3C HUB Controller Port 0 IO strength setting to control the Controller Port 0 output driver
> +      strength.
> +
> +      This property is optional. If not provided, IO strength configuration is not modified in I3C
> +      HUB.
> +
> +  cp1-io-strength:
> +    enum:
> +      - 20Ohms
> +      - 30Ohms
> +      - 40Ohms
> +      - 50Ohms
> +    description: |
> +      I3C HUB Controller Port 1 IO strength setting to control the Controller Port 1 output driver
> +      strength.
> +
> +      This property is optional. If not provided, IO strength configuration is not modified in I3C
> +      HUB.
> +
> +  tp0145-io-strength:
> +    enum:
> +      - 20Ohms
> +      - 30Ohms
> +      - 40Ohms
> +      - 50Ohms
> +    description: |
> +      I3C HUB Target Ports 0/1/4/5 IO strength setting to control the Target Ports 0/1/4/5 output
> +      driver strength.
> +
> +      This property is optional. If not provided, IO strength configuration is not modified in I3C
> +      HUB.
> +
> +  tp2367-io-strength:
> +    enum:
> +      - 20Ohms
> +      - 30Ohms
> +      - 40Ohms
> +      - 50Ohms
> +    description: |
> +      I3C HUB Target Ports 2/3/6/7 IO strength setting to control the Target Ports 2/3/6/7 output
> +      driver strength.
> +
> +      This property is optional. If not provided, IO strength configuration is not modified in I3C
> +      HUB.
> +
> +  id:
> +    enum:
> +      - 0
> +      - 1
> +      - 3
> +    description: |
> +      I3C HUB ID based on CSEL pin. There are three possible values:
> +      0 - CP0 is selected as primary Controller Port
> +      1 - Primary Controller Port is selected by software by writing the REG#56
> +      3 - CP1 is selected as primary Controller Port
> +
> +      I3C HUB driver reads CSEL pin status (REG#121[5:4]) and tries to find DT node with matching
> +      value in 'id' property.
> +
> +      This property is optional. If not provided, DT node can only be used by the I3C HUB driver if
> +      there is no others with matching 'id' or 'id-cp1'. If there is a multiple DT nodes with no
> +      'id' property - the first one will be chosen by I3C HUB driver. If there is a multiple DT
> +      nodes with matching 'id' property - the first one will be chosen by I3C HUB driver.
> +
> +      If both 'id' and 'id-cp1' are available, DT node will chosen only when both values match those
> +      read from I3C HUB.
> +
> +  id-cp1:
> +    enum:
> +      - 0
> +      - 1
> +      - 2
> +      - 3
> +    description: |
> +      I3C HUB ID based on CP1 SDA and SCL pins state probed during power on.
> +
> +      I3C HUB driver reads CP1 SDA and SCL pin status and tries to find DT node with matching value
> +      in 'id-cp1' property.
> +
> +      This property is optional. If not provided, DT node can only be used by the I3C HUB
> +      driver if there is no others with matching 'id' or 'id-cp1'. If there is a multiple DT nodes
> +      with no 'id-cp1' property - the first one will be chosen by I3C HUB driver. If there is a
> +      multiple DT nodes with matching 'id-cp1' property - the first one will be chosen by I3C HUB
> +      driver.
> +
> +      If both 'id' and 'id-cp1' are available, DT node will chosen only when both values match those
> +      read from I3C HUB.
> +
> +patternProperties:
> +  "@[0-9]$":
> +    type: object
> +    description: |
> +      I3C HUB Target Port child, should be named: target-port@<target-port-id>
> +
> +    properties:
> +      mode:
> +        enum:
> +          - disabled
> +          - i3c
> +          - smbus
> +          - gpio
> +        description: |
> +          I3C HUB Target Port mode setting to control Target Port functionality.
> +
> +          This property is optional. If not provided, Target Port mode configuration is not modified
> +          in I3C HUB.
> +
> +      pullup:
> +        enum:
> +          - disabled
> +          - enabled
> +        description: |
> +          I3C HUB Target Port pull-up setting to disable/enable Target Port pull-up.
> +
> +          This property is optional. If not provided, Target Port pull-up configuration is not
> +          modified in I3C HUB.
> +
> +      always-enable:
> +        type: boolean
> +        description: |
> +          I3C HUB Target Port settings to control the port enable/disable policy.
> +
> +          This property is optional. If not provided, Target Port is enabled only on accessing to
> +          the devices connected to it and the port is disabled automatically after the accessing
> +          is done. If provided, the Target Port is always enabled.
> +
> +      polling-interval-ms:
> +        type: uint32
> +        description: |
> +          I3C HUB Target Port SMBus polling interval in milliseconds.
> +
> +          This property is optional. If not provided or set to 0, polling is disabled and the driver
> +          uses IBI (In-Band Interrupts). If provided with a positive value, polling is enabled for
> +          this Target Port with the given period.Note: this positive value only affects the SMBus
> +          target agent polling. The SMBus controller agent polling interval is computed dynamically
> +          from clock and data length.
> +
> +      clock-frequency:
> +        type: uint32
> +        enum:
> +          - 100000
> +          - 200000
> +          - 400000
> +          - 1000000
> +        description: |
> +          I3C HUB Target Port SMBus clock frequency in Hz.
> +
> +          This property follows the standard I2C 'clock-frequency' semantics.
> +          Applies only when the Target Port mode is set to "smbus".
> +          Optional; if not provided, the driver uses 400000 Hz by default.
> +
> +additionalProperties: true
> +
> +examples:
> +  - |
> +    i3c-master@d040000 {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +
> +      hub@0,0 {
> +        cp0-ldo-en = "disabled";
> +        cp1-ldo-en = "enabled";
> +        cp0-ldo-volt = "1.0V";
> +        cp1-ldo-volt = "1.1V";
> +        tp0145-ldo-en = "enabled";
> +        tp2367-ldo-en = "disabled";
> +        tp0145-ldo-volt = "1.2V";
> +        tp2367-ldo-volt = "1.8V";
> +        tp0145-pullup = "2k";
> +        tp2367-pullup = "500R";
> +        tp0145-io-strength = "50Ohms";
> +        tp2367-io-strength = "30Ohms";
> +        cp0-io-strength = "20Ohms";
> +        cp1-io-strength = "40Ohms";
> +
> +        target-port@0 {
> +          mode = "i3c";
> +          pullup = "enabled";
> +          always_enable;
> +        };
> +        target-port@1 {
> +          mode = "smbus";
> +          pullup = "enabled";
> +          clock-frequency = <1000000>;
> +          polling-interval-ms = <10>;
> +          backend@10{
> +              compatible = "i2c-slave-mqueue";
> +              reg = <(0x10 | I2C_OWN_SLAVE_ADDRESS)>;
> +          };
> +        };
> +        target-port@2 {
> +          mode = "gpio";
> +          pullup = "disabled";
> +        };
> +        target-port@3 {
> +          mode = "disabled";
> +          pullup = "disabled";
> +        };
> +      };
> +    };
> +
> +  - |
> +    i3c-master@d040000 {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +
> +      hub@70,3C000000100 {
> +        reg = <0x70 0x3C0 0x00000100>;
> +        assigned-address = <0x70>;
> +        dcr = <0xC2>;
> +
> +        cp0-ldo-en = "disabled";
> +        cp1-ldo-en = "enabled";
> +        cp0-ldo-volt = "1.0V";
> +        cp1-ldo-volt = "1.1V";
> +        tp0145-ldo-en = "enabled";
> +        tp2367-ldo-en = "disabled";
> +        tp0145-ldo-volt = "1.2V";
> +        tp2367-ldo-volt = "1.8V";
> +        tp0145-pullup = "2k";
> +        tp2367-pullup = "500R";
> +        tp0145-io-strength = "50Ohms";
> +        tp2367-io-strength = "30Ohms";
> +        cp0-io-strength = "20Ohms";
> +        cp1-io-strength = "40Ohms";
> +
> +        target-port@0 {
> +          mode = "i3c";
> +          pullup = "enabled";
> +          always-enable;
> +        };
> +        target-port@1 {
> +          mode = "smbus";
> +          pullup = "enabled";
> +          backend@12{
> +              compatible = "i2c-slave-mqueue";
> +              reg = <(0x12 | I2C_OWN_SLAVE_ADDRESS)>;
> +          };
> +        };
> +        target-port@2 {
> +          mode = "gpio";
> +          pullup = "disabled";
> +        };
> +        target-port@3 {
> +          mode = "disabled";
> +          pullup = "disabled";
> +        };
> +      };
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 2fb1c75afd16..71ee5071ac0f 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -12214,6 +12214,12 @@ S:	Supported
>  F:	Documentation/devicetree/bindings/i3c/renesas,i3c.yaml
>  F:	drivers/i3c/master/renesas-i3c.c
>
> +I3C HUB DRIVER FOR REALTEK RTS490X
> +M:	zain_zhou <zain_zhou@realsil.com.cn>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/i3c/realtek,rts490x-i3c-hub.yaml
> +F:	drivers/staging/rts490x/
> +
>  I3C DRIVER FOR SYNOPSYS DESIGNWARE
>  S:	Orphan
>  F:	Documentation/devicetree/bindings/i3c/snps,dw-i3c-master.yaml
> --
> 2.34.1
>

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