[RFC PATCH 04/11] i2c: dt-bindings: configuration settings

Krishna Yarlagadda
2024-05-06T22:53:01Z

I2C interface timing registers are configured using config setting
framework. Document available properties for Tegra I2C controllers.

Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
---
.../bindings/i2c/nvidia,tegra20-i2c.yaml | 104 ++++++++++++++++++
1 file changed, 104 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/nvidia,tegra20-i2c.yaml b/Documentation/devicetree/bindings/i2c/nvidia,tegra20-i2c.yaml
index 424a4fc218b6..3b22e75e5aa0 100644
--- a/Documentation/devicetree/bindings/i2c/nvidia,tegra20-i2c.yaml
+++ b/Documentation/devicetree/bindings/i2c/nvidia,tegra20-i2c.yaml
@@ -119,6 +119,96 @@ properties:
- const: rx
- const: tx

+ config:
+ description: Config settings for I2C devices enlisted with I2C controller.
+ Config setting is the configuration based on chip/board/system
+ characterization on interface/controller settings. This is needed for
+ - making the controller internal configuration to better perform
+ - making the interface to work proper by setting drive strength, slew
+ rates etc
+ - making the low power leakage.
+ There are two types of recommended configuration settings
+ - Controller register specific for internal operation of controller.
+ - Pad control/Pinmux/pincontrol registers for interfacing.
+ These configurations can further be categorized as static and dynamic.
+ - Static config does not change until a controller is reset.
+ - Dynamic config changes based on mode or condition, controller is
+ operating in.
+ I2C has configuration based on clock speed and has below modes.
+ - common is set on all speeds and can be overridden by speed mode.
+ - high is set when clock mode is high speed.
+ - fastplus is set when clock mode is fast plus.
+ - fast is set when clock mode is fast mode.
+ - standard is set when clock mode is standard mode.
+ $ref: /schemas/misc/nvidia,tegra-config-settings.yaml
+ unevaluatedProperties: false
+ properties:
+ nvidia,i2c-clk-divisor-hs-mode:
+ description: I2C clock divisor for HS mode.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-clk-divisor-fs-mode:
+ description: I2C clock divisor for FS mode.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-hs-sclk-high-period:
+ description: I2C high speed sclk high period.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-hs-sclk-low-period:
+ description: I2C high speed sclk low period.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-hs-stop-setup-time:
+ description: I2C high speed stop setup time.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-hs-start-hold-time:
+ description: I2C high speed start hold time.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-hs-start-setup-time:
+ description: I2C high speed start setup time.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-sclk-high-period:
+ description: I2C sclk high period.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-sclk-low-period:
+ description: I2C sclk low period.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-bus-free-time:
+ description: I2C bus free time.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-stop-setup-time:
+ description: I2C stop setup time.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-start-hold-time:
+ description: I2C start hold time.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+ nvidia,i2c-start-setup-time:
+ description: I2C start setup time.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 0xffff
+
allOf:
- $ref: /schemas/i2c/i2c-controller.yaml
- if:
@@ -189,4 +279,18 @@ examples:

#address-cells = <1>;
#size-cells = <0>;
+ config {
+ common {
+ nvidia,i2c-hs-sclk-high-period = <0x03>;
+ nvidia,i2c-hs-sclk-low-period = <0x08>;
+ };
+ fast {
+ nvidia,i2c-clk-divisor-fs-mode = <0x3c>;
+ nvidia,i2c-sclk-high-period = <0x02>;
+ };
+ fastplus {
+ nvidia,i2c-clk-divisor-fs-mode = <0x4f>;
+ nvidia,i2c-sclk-high-period = <0x07>;
+ };
+ };
};
--
2.43.2