Re: [PATCH v3 1/2] dt-bindings: pwm: Add Xilinx AXI Timer

[Sean Anderson]

On 5/12/21 10:16 PM, Rob Herring wrote:
> On Tue, May 11, 2021 at 03:12:37PM -0400, Sean Anderson wrote:
>> This adds a binding for the Xilinx LogiCORE IP AXI Timer. This device is
>> a "soft" block, so it has many parameters which would not be
>> configurable in most hardware. This binding is usually automatically
>> generated by Xilinx's tools, so the names and values of some properties
>> must be kept as they are. Replacement properties have been provided for
>> new device trees.
>
> Because you have some tool generating properties is not a reason we have
> to accept them upstream.

These properties are already in arch/microblaze/boot/dts/system.dts and
in the devicetree supplied to Linux by qemu. Removing these properties
will break existing setups, which I would like to avoid.

> 'deprecated' is for what *we* have deprecated.

Ok. I will remove that then.

>
> In this case, I don't really see the point in defining new properties
> just to have bool.

I don't either, but it was requested, by Michal...

>
>>
>> Because we need to init timer devices so early in boot, the easiest way
>> to configure things is to use a device tree property. For the moment
>> this is 'xlnx,pwm', but this could be extended/renamed/etc. in the
>> future if these is a need for a generic property.
>
> No...
>
>> Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxx>
>> ---
>> How should the clocking situation be documented? For the moment I have
>> just left clock as optional, but should clock-frequency be documented?
>>
>> Changes in v3:
>> - Mark all boolean-as-int properties as deprecated
>> - Add xlnx,pwm and xlnx,gen?-active-low properties.
>> - Make newer replacement properties mutually-exclusive with what they
>>    replace
>> - Add an example with non-deprecated properties only.
>>
>> Changes in v2:
>> - Use 32-bit addresses for example binding
>>
>>   .../bindings/pwm/xlnx,axi-timer.yaml          | 142 ++++++++++++++++++
>>   1 file changed, 142 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/pwm/xlnx,axi-timer.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/pwm/xlnx,axi-timer.yaml b/Documentation/devicetree/bindings/pwm/xlnx,axi-timer.yaml
>> new file mode 100644
>> index 000000000000..a5e90658e31a
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/pwm/xlnx,axi-timer.yaml
>> @@ -0,0 +1,142 @@
>> +# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/pwm/xlnx,axi-timer.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Xilinx LogiCORE IP AXI Timer Device Tree Binding
>> +
>> +maintainers:
>> +  - Sean Anderson <sean.anderson@xxxxxxxx>
>> +
>> +properties:
>> +  compatible:
>> +    oneOf:
>> +      - items:
>> +        - const: xlnx,axi-timer-2.0
>> +        - const: xlnx,xps-timer-1.00.a
>> +      - const: xlnx,xps-timer-1.00.a
>> +
>> +  clocks:
>> +    maxItems: 1
>> +
>> +  clock-names:
>> +    const: s_axi_aclk
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  xlnx,count-width:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    minimum: 8
>> +    maximum: 32
>> +    description:
>> +      The width of the counter(s), in bits.
>> +
>> +  xlnx,gen0-assert:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    enum: [ 0, 1 ]
>> +    default: 1
>> +    deprecated: true
>> +    description:
>> +      The polarity of the generateout0 signal. 0 for active-low, 1 for active-high.
>> +
>> +  xlnx,gen0-active-low:
>> +    $ref: /schemas/types.yaml#/definitions/flag
>> +    description:
>> +      The generate0 signal is active-low.
>> +
>> +  xlnx,gen1-assert:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    enum: [ 0, 1 ]
>> +    default: 1
>> +    deprecated: true
>> +    description:
>> +      The polarity of the generateout1 signal. 0 for active-low, 1 for active-high.
>> +
>> +  xlnx,gen1-active-low:
>> +    $ref: /schemas/types.yaml#/definitions/flag
>> +    description:
>> +      The generate1 signal is active-low.
>> +
>> +  xlnx,one-timer-only:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    enum: [ 0, 1 ]
>> +    deprecated: true
>> +    description:
>> +      Whether only one timer is present in this block.
>> +
>> +  xlnx,single-timer:
>> +    $ref: /schemas/types.yaml#/definitions/flag
>> +    description:
>> +      Only one timer is present in this block.
>> +
>> +  xlnx,pwm:
>> +    $ref: /schemas/types.yaml#/definitions/flag
>> +    description:
>> +      This timer should be configured as a PWM.
>
> If a PWM, perhaps you want a '#pwm-cells' property which can serve as
> the hint to configure as a PWM.

Ok, that's a good idea.

--Sean

>
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - xlnx,count-width
>> +
>> +allOf:
>> +  - if:
>> +      required:
>> +        - clocks
>> +    then:
>> +      required:
>> +        - clock-names
>> +
>> +  - if:
>> +      required:
>> +        - xlnx,gen0-active-low
>> +    then:
>> +      not:
>> +        required:
>> +          - xlnx,gen0-assert
>> +
>> +  - if:
>> +      required:
>> +        - xlnx,gen0-active-low
>> +    then:
>> +      not:
>> +        required:
>> +          - xlnx,gen0-assert
>> +
>> +  - if:
>> +      required:
>> +        - xlnx,one-timer-only
>> +    then:
>> +      not:
>> +        required:
>> +          - xlnx,single-timer
>> +
>> +additionalProperties: true
>> +
>> +examples:
>> +  - |
>> +    axi_timer_0: timer@800e0000 {
>> +        clock-names = "s_axi_aclk";
>> +        clocks = <&zynqmp_clk 71>;
>> +        compatible = "xlnx,axi-timer-2.0", "xlnx,xps-timer-1.00.a";
>> +        reg = <0x800e0000 0x10000>;
>> +        xlnx,count-width = <0x20>;
>> +        xlnx,gen0-assert = <0x1>;
>> +        xlnx,gen1-assert = <0x1>;
>> +        xlnx,one-timer-only = <0x0>;
>> +        xlnx,trig0-assert = <0x1>;
>> +        xlnx,trig1-assert = <0x1>;
>> +    };
>> +
>> +  - |
>> +    axi_timer_0: timer@800e0000 {
>> +        clock-names = "s_axi_aclk";
>> +        clocks = <&zynqmp_clk 71>;
>> +        compatible = "xlnx,axi-timer-2.0", "xlnx,xps-timer-1.00.a";
>> +        reg = <0x800e0000 0x10000>;
>> +        xlnx,count-width = <0x20>;
>> +        xlnx,gen0-active-low;
>> +        xlnx,single-timer;
>> +    };
>> --
>> 2.25.1
>>