Message-ID: <264f3ab9-fbf7-8f5d-af57-26b8602a6fbd@seco.com>
Date:   Tue, 31 Aug 2021 16:13:29 -0400
From:   Sean Anderson <sean.anderson@...o.com>
To:     Rob Herring <robh@...nel.org>
Cc:     linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>,
        Alvaro Gamez <alvaro.gamez@...ent.com>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        linux-arm-kernel@...ts.infradead.org,
        Lee Jones <lee.jones@...aro.org>, michal.simek@...inx.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 1/3] dt-bindings: pwm: Add Xilinx AXI Timer



On 8/31/21 4:11 PM, Rob Herring wrote:
> On Thu, Aug 26, 2021 at 05:18:28PM -0400, Sean Anderson wrote:
>> This adds a binding for the Xilinx LogiCORE IP AXI Timer. This device is a
>> "soft" block, so it has some 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 should be kept as they
>> are, if possible. In addition, this binding is already in the kernel at
>> arch/microblaze/boot/dts/system.dts, and in user software such as QEMU.
>>
>> The existing driver uses the clock-frequency property, or alternatively the
>> /cpus/timebase-frequency property as its frequency input. Because these
>> properties are deprecated, they have not been included with this schema.
>> All new bindings should use the clocks/clock-names properties to specify
>> the parent clock.
>>
>> Because we need to init timer devices so early in boot, we determine if we
>> should use the PWM driver or the clocksource/clockevent driver by the
>> presence/absence, respectively, of #pwm-cells. Because both counters are
>> used by the PWM, there is no need for a separate property specifying which
>> counters are to be used for the PWM.
>>
>> Signed-off-by: Sean Anderson <sean.anderson@...o.com>
>> ---
>>
>> Changes in v6:
>> - Fix incorrect schema id
>> - Enumerate possible counter widths
>>
>> Changes in v5:
>> - Update commit message to reflect revisions
>> - Fix indentation lint
>> - Add example for timer binding
>> - Remove xlnx,axi-timer-2.0 compatible string
>> - Move schema into the timer directory
>>
>> Changes in v4:
>> - Remove references to generate polarity so this can get merged
>> - Predicate PWM driver on the presence of #pwm-cells
>> - Make some properties optional for clocksource drivers
>>
>> 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/timer/xlnx,xps-timer.yaml        | 90 +++++++++++++++++++
>>  1 file changed, 90 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/timer/xlnx,xps-timer.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/timer/xlnx,xps-timer.yaml b/Documentation/devicetree/bindings/timer/xlnx,xps-timer.yaml
>> new file mode 100644
>> index 000000000000..5be353a642aa
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/timer/xlnx,xps-timer.yaml
>> @@ -0,0 +1,90 @@
>> +# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/timer/xlnx,xps-timer.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Xilinx LogiCORE IP AXI Timer Device Tree Binding
>> +
>> +maintainers:
>> +  - Sean Anderson <sean.anderson@...o.com>
>> +
>> +properties:
>> +  compatible:
>> +    contains:
>> +      const: xlnx,xps-timer-1.00.a
>> +
>> +  clocks:
>> +    maxItems: 1
>> +
>> +  clock-names:
>> +    const: s_axi_aclk
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  xlnx,count-width:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    enum: [8, 16, 32]
>> +    default: 32
>> +    description:
>> +      The width of the counter(s), in bits.
>> +
>> +  xlnx,one-timer-only:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    enum: [ 0, 1 ]
>> +    description:
>> +      Whether only one timer is present in this block.
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - xlnx,one-timer-only
>> +
>> +allOf:
>> +  - if:
>> +      required:
>> +        - '#pwm-cells'
>> +    then:
>> +      allOf:
>> +        - required:
>> +            - clocks
>> +        - properties:
>> +            xlnx,one-timer-only:
>> +              const: 0
>> +    else:
>> +      required:
>> +        - interrupts
>> +  - if:
>> +      required:
>> +        - clocks
>> +    then:
>> +      required:
>> +        - clock-names
>> +
>> +additionalProperties: true
>
> This needs to be false. What else do you expect to be present?

There are additional properties present in the existing in-tree bindings
for this device. Should I instead set "unevaluatedProperties: false"?

--Sean

>
>> +
>> +examples:
>> +  - |
>> +    timer@...e0000 {
>> +        clock-names = "s_axi_aclk";
>> +        clocks = <&zynqmp_clk 71>;
>> +        compatible = "xlnx,xps-timer-1.00.a";
>> +        reg = <0x800e0000 0x10000>;
>> +        interrupts = <0 39 2>;
>> +        xlnx,count-width = <16>;
>> +        xlnx,one-timer-only = <0x0>;
>> +    };
>> +
>> +    timer@...f0000 {
>> +        #pwm-cells = <0>;
>> +        clock-names = "s_axi_aclk";
>> +        clocks = <&zynqmp_clk 71>;
>> +        compatible = "xlnx,xps-timer-1.00.a";
>> +        reg = <0x800e0000 0x10000>;
>> +        xlnx,count-width = <32>;
>> +        xlnx,one-timer-only = <0x0>;
>> +    };
>> --
>> 2.25.1
>>
>>
>

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