[PATCH v4 1/6] dt-bindings: i3c: Convert controller description to yaml
Rob Herring
robh at kernel.org
Fri Jan 15 12:03:12 EST 2021
On Thu, Jan 14, 2021 at 06:55:53PM +0100, Miquel Raynal wrote:
> Attempting a conversion of the i3c.txt file to yaml schema with
> minimal content changes.
>
> Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
> ---
> Documentation/devicetree/bindings/i3c/i3c.txt | 140 -------------
> .../devicetree/bindings/i3c/i3c.yaml | 186 ++++++++++++++++++
> 2 files changed, 186 insertions(+), 140 deletions(-)
> delete mode 100644 Documentation/devicetree/bindings/i3c/i3c.txt
> create mode 100644 Documentation/devicetree/bindings/i3c/i3c.yaml
> diff --git a/Documentation/devicetree/bindings/i3c/i3c.yaml b/Documentation/devicetree/bindings/i3c/i3c.yaml
> new file mode 100644
> index 000000000000..79df533ab094
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i3c/i3c.yaml
> @@ -0,0 +1,186 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/i3c/i3c.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: I3C bus binding
> +
> +maintainers:
> + - Alexandre Belloni <alexandre.belloni at bootlin.com>
> + - Miquel Raynal <miquel.raynal at bootlin.com>
> +
> +description: |
> + I3C busses can be described with a node for the primary I3C controller device
> + and a set of child nodes for each I2C or I3C slave on the bus. Each of them
> + may, during the life of the bus, request mastership.
> +
> +properties:
> + $nodename:
> + pattern: "^i3c-master(@.*|-[0-9a-f])*$"
> +
> + "#address-cells":
> + const: 3
> + description: |
> + Each I2C device connected to the bus should be described in a subnode.
> +
> + All I3C devices are supposed to support DAA (Dynamic Address Assignment),
> + and are thus discoverable. So, by default, I3C devices do not have to be
> + described in the device tree. This being said, one might want to attach
> + extra resources to these devices, and those resources may have to be
> + described in the device tree, which in turn means we have to describe
> + I3C devices.
> +
> + Another use case for describing an I3C device in the device tree is when
> + this I3C device has a static I2C address and we want to assign it a
> + specific I3C dynamic address before the DAA takes place (so that other
> + devices on the bus can't take this dynamic address).
> +
> + "#size-cells":
> + const: 0
> +
> + i3c-scl-hz:
> + $ref: /schemas/types.yaml#/definitions/uint32
With a unit suffix, you don't need the type.
> + description: |
> + Frequency of the SCL signal used for I3C transfers. When undefined, the
> + default value should be 12.5MHz.
> +
> + May not be supported by all controllers.
> +
> + i2c-scl-hz:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description: |
> + Frequency of the SCL signal used for I2C transfers. When undefined, the
> + default should be to look at LVR (Legacy Virtual Register) values of
> + I2C devices described in the device tree to determine the maximum I2C
> + frequency.
> +
> + May not be supported by all controllers.
> +
> +required:
> + - "#address-cells"
> + - "#size-cells"
> +
> +patternProperties:
> + "^.*@[0-9a-f]+$":
You can drop '^.*':
"@[0-9a-f]+$"
> + type: object
> + description: |
> + I2C child, should be named: <device-type>@<i2c-address>
> +
> + All properties described in Documentation/devicetree/bindings/i2c/i2c.txt
> + are valid here, except the reg property whose content is changed.
> +
> + properties:
> + compatible:
> + description:
> + Compatible of the I2C device.
> +
> + reg:
> + items:
> + - description: |
> + 1st cell
> + ========
> +
> + I2C address. 10 bit addressing is not supported. Devices with
> + 10-bit address can't be properly passed through DEFSLVS command.
> +
> + 2nd cell
> + ========
> +
> + Should be 0.
> +
> + 3rd cell
> + ========
> +
> + Shall encode the I3C LVR (Legacy Virtual Register):
> + bit[31:8]: unused/ignored
> + bit[7:5]: I2C device index. Possible values:
> + * 0: I2C device has a 50 ns spike filter
> + * 1: I2C device does not have a 50 ns spike filter but supports
> + high frequency on SCL
> + * 2: I2C device does not have a 50 ns spike filter and is not
> + tolerant to high frequencies
> + * 3-7: reserved
> + bit[4]: tell whether the device operates in FM (Fast Mode) or
> + FM+ mode:
> + * 0: FM+ mode
> + * 1: FM mode
> + bit[3:0]: device type
> + * 0-15: reserved
We can do a bit better:
reg:
items:
- items: # Note: drop the '-' if we support more than 1 entry
- description: I2C address...
maximum: 0x7f # Not sure this works, do we support the high
# flag bits here?
- const: 0
- description: I3C LVR (Legacy Virtual Register)...
> +
> + required:
> + - compatible
> + - reg
> +
> + "^.*@[0-9a-f]+,[0-9a-f]+$":
> + type: object
> + description: |
> + I3C child, should be named: <device-type>@<static-i2c-address>,<i3c-pid>
> +
> + properties:
> + reg:
> + items:
> + - description: |
> + 1st cell
> + ========
> +
> + Encodes the static I2C address. Should be 0 if the device does not
> + have one (0 is not a valid I2C address).
> +
> + 2nd and 3rd cells
> + =================
> +
> + ProvisionalID (following the PID definition provided by the I3C
> + specification).
> +
> + Cell 2 contains the manufacturer ID left-shifted by 1. Cell 3
> + contains the ORing of the part ID left-shifted by 16, the instance
> + ID left-shifted by 12 and extra information.
Similar rework here.
> +
> + assigned-address:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + minimum: 0x01
> + maximum: 0xFF
> + description: |
> + Dynamic address to be assigned to this device. This property is only
> + valid if the I3C device has a static address (first cell of the reg
> + property != 0).
> +
> + required:
> + - reg
> +
> +additionalProperties: true
> +
> +examples:
> + - |
> + i3c-master at d040000 {
> + compatible = "cdns,i3c-master";
> + clocks = <&coreclock>, <&i3csysclock>;
> + clock-names = "pclk", "sysclk";
> + interrupts = <3 0>;
> + reg = <0x0d040000 0x1000>;
> + #address-cells = <3>;
> + #size-cells = <0>;
> + i2c-scl-hz = <100000>;
> +
> + /* I2C device. */
> + nunchuk: nunchuk at 52 {
> + compatible = "nintendo,nunchuk";
> + reg = <0x52 0x0 0x10>;
> + };
> +
> + /* I3C device with a static I2C address. */
> + thermal_sensor: sensor at 68,39200144004 {
> + reg = <0x68 0x392 0x144004>;
> + assigned-address = <0xa>;
> + };
> +
> + /*
> + * I3C device without a static I2C address but requiring
> + * resources described in the DT.
> + */
> + sensor at 0,39200154004 {
> + reg = <0x0 0x392 0x154004>;
> + clocks = <&clock_provider 0>;
> + };
> + };
> --
> 2.20.1
>
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