Re: [PATCH v3 1/4] dt-bindings: mfd: Add bindings for Ampere Altra SMPro drivers

Quan Nguyen
2021-04-14T08:29:36Z

On 13/04/2021 20:49, Rob Herring wrote:
> On Fri, Apr 09, 2021 at 10:13:29AM +0700, Quan Nguyen wrote:
>> Adds device tree bindings for SMPro drivers found on the Mt.Jade hardware
>> reference platform with Ampere's Altra Processor family.
>>
>> Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
>> ---
>> .../bindings/hwmon/ampere,ac01-hwmon.yaml | 28 +++++
>> .../devicetree/bindings/mfd/ampere,smpro.yaml | 105 ++++++++++++++++++
>> 2 files changed, 133 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/hwmon/ampere,ac01-hwmon.yaml
>> create mode 100644 Documentation/devicetree/bindings/mfd/ampere,smpro.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/hwmon/ampere,ac01-hwmon.yaml b/Documentation/devicetree/bindings/hwmon/ampere,ac01-hwmon.yaml
>> new file mode 100644
>> index 000000000000..fbf7ec754160
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/hwmon/ampere,ac01-hwmon.yaml
>> @@ -0,0 +1,28 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/hwmon/ampere,ac01-hwmon.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Hardware monitoring driver for the Ampere Altra SMPro
>> +
>> +maintainers:
>> + - Quan Nguyen <quan@os.amperecomputing.com>
>> +
>> +description: |
>> + This module is part of the Ampere Altra SMPro multi-function device. For more
>> + details see ../mfd/ampere,smpro.yaml.
>> +
>> +properties:
>> + compatible:
>> + enum:
>> + - ampere,ac01-hwmon
>> +
>> + reg:
>> + maxItems: 1
>> +
>> +required:
>> + - compatible
>> + - reg
>> +
>> +additionalProperties: false
>> diff --git a/Documentation/devicetree/bindings/mfd/ampere,smpro.yaml b/Documentation/devicetree/bindings/mfd/ampere,smpro.yaml
>> new file mode 100644
>> index 000000000000..5613c420869e
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/mfd/ampere,smpro.yaml
>> @@ -0,0 +1,105 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/mfd/ampere,smpro.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Ampere Altra SMPro firmware driver
>> +
>> +maintainers:
>> + - Quan Nguyen <quan@os.amperecomputing.com>
>> +
>> +description: |
>> + Ampere Altra SMPro firmware may contain different blocks like hardware
>> + monitoring, error monitoring and other miscellaneous features.
>> +
>> +properties:
>> + compatible:
>> + enum:
>> + - ampere,smpro
>
> Again, not very specific. There's only 1 version of 'smpro' h/w or
> firmware? Are the firmware version and features discoverable? If not,
> you need to be more specific (or better yet, make them discoverable).
>
Hi Rob,

So far, there's nothing to guarantee this is the only version of SMPro
and neither firmware version nor features that are discoverable.

In fact, it was "ampere,ac01-smpro" specifically in my v1. But this is
the "ampere,smpro" in arch/arm/boot/dts/nuvoton-npcm730-kudo.dts, that
is why it got changed to "ampere,smpro" to avoid changes in that dts file.

I'm thinking about change it back to "ampere,ac01-smpro" in next version
to make this compatible string more specific.

>> +
>> + reg:
>> + description:
>> + I2C device address.
>> + maxItems: 1
>> +
>> + "#address-cells":
>> + const: 1
>> +
>> + "#size-cells":
>> + const: 0
>> +
>> +patternProperties:
>> + "^hwmon(@[0-9a-f]+)?$":
>> + $ref: ../hwmon/ampere,ac01-hwmon.yaml
>> +
>> + "^misc(@[0-9a-f]+)?$":
>
> You don't need these child nodes in DT if there are no resources
> associated with them. The parent driver can instantiate all the
> sub-functions.
>

From v3, there is a "reg" property introduced for the child driver,
especially for the misc driver. This is unavoidable because other
properties might be introduced in future for other misc features.

>> + type: object
>> + description: |
>> + This module is part of the Ampere Altra SMPro multi-function device
>> + to support miscellaneous features
>> + properties:
>> + compatible:
>> + enum:
>> + - ampere,ac01-misc
>> + reg:
>> + maxItems: 1
>> +
>> + required:
>> + - compatible
>> + - reg
>> +
>> + "^errmon(@[0-9a-f]+)?$":
>> + type: object
>> + description: |
>> + This module is part of the Ampere Altra SMPro multi-function device
>> + that supports error monitoring feature.
>> +
>> + properties:
>> + compatible:
>> + enum:
>> + - ampere,ac01-errmon
>> + reg:
>> + maxItems: 1
>> +
>> + required:
>> + - compatible
>> + - reg
>> +
>> +required:
>> + - "#address-cells"
>> + - "#size-cells"
>> + - compatible
>> + - reg
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> + - |
>> + i2c {
>> + #address-cells = <1>;
>> + #size-cells = <0>;
>> +
>> + smpro@4f {
>> + compatible = "ampere,smpro";
>> + reg = <0x4f>;
>> + #address-cells = <1>;
>> + #size-cells = <0>;
>> +
>> + hwmon@10 {
>> + compatible = "ampere,ac01-hwmon";
>> + reg = <0x10>;
>> + };
>> +
>> + misc@b0 {
>> + compatible = "ampere,ac01-misc";
>> + reg = <0xb0>;
>> + };
>> +
>> + errmon@80 {
>> + compatible = "ampere,ac01-errmon";
>> + reg = <0x80>;
>> + };
>> +
>> + };
>> + };
>> --
>> 2.28.0
>>