Re: [PATCH v6 06/17] dt-bindings: mfd: amd,pensando-elbasr: Add AMD Pensando Elba System Resource chip

[Larson, Bradley]

On 8/22/22 7:25 AM, Rob Herring wrote:
> On Sat, Aug 20, 2022 at 12:57:39PM -0700, Brad Larson wrote:
>> From: Brad Larson <blarson@xxxxxxx>
>>
>> Add support for the AMD Pensando Elba SoC System Resource chip
>> using the SPI interface.  The Elba SR is a Multi-function Device
>> supporting device register access using CS0, smbus interface for
>> FRU and board peripherals using CS1, dual Lattice I2C masters for
>> transceiver management using CS2, and CS3 for flash access.
>>
>> Signed-off-by: Brad Larson <blarson@xxxxxxx>
>> ---
>>   .../bindings/mfd/amd,pensando-elbasr.yaml     | 97 +++++++++++++++++++
>>   1 file changed, 97 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/mfd/amd,pensando-elbasr.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/mfd/amd,pensando-elbasr.yaml b/Documentation/devicetree/bindings/mfd/amd,pensando-elbasr.yaml
>> new file mode 100644
>> index 000000000000..ded347c3352c
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/mfd/amd,pensando-elbasr.yaml
>> @@ -0,0 +1,97 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fschemas%2Fmfd%2Famd%2Cpensando-elbasr.yaml%23&amp;data=05%7C01%7CBradley.Larson%40amd.com%7Cd02c183f9a29492180fb08da844a3458%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637967751571358185%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=WHkA6tPbaDanQuMSaAiWUG3fBTfDVlWXMdeaO5t%2F3Ok%3D&amp;reserved=0
>> +$schema: https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fmeta-schemas%2Fcore.yaml%23&amp;data=05%7C01%7CBradley.Larson%40amd.com%7Cd02c183f9a29492180fb08da844a3458%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637967751571358185%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=FDig31luqeo4pOZXfuOAGiOLi0kVqFU8ExnBi5gorlY%3D&amp;reserved=0
>> +
>> +title: AMD Pensando Elba SoC Resource Controller bindings
>> +
>> +description: |
>> +  AMD Pensando Elba SoC Resource Controller is a set of
>> +  miscellaneous control/status registers accessed on CS0,
>> +  a designware i2c master/slave on CS1, a Lattice rd1173
>> +  dual i2c master on CS2, and flash on CS3.  The /dev interfaces
>> +  created are /dev/pensr0.<CS>.  Hardware reset of the eMMC
> /dev is a Linux thing and not relevant for the bindings.
>

Removed mention of the dev interfaces


>> +  is implemented by a sub-device reset-controller which accesses
>> +  a CS0 control register.
>> +
>> +maintainers:
>> +  - Brad Larson <blarson@xxxxxxx>
>> +
>> +properties:
>> +  compatible:
>> +    items:
>> +      - enum:
>> +          - amd,pensando-elbasr
>> +
>> +  spi-max-frequency:
>> +    description: Maximum SPI frequency of the device in Hz.
> No need for generic descriptions of common properties.

Changed to "spi-max-frequency: true" and moved to end of properties.

>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  '#address-cells':
>> +    const: 1
>> +
>> +  '#size-cells':
>> +    const: 0
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - spi-max-frequency
>> +
>> +patternProperties:
>> +  '^reset-controller@[a-f0-9]+$':
>> +    $ref: /schemas/reset/amd,pensando-elbasr-reset.yaml
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>> +
>> +    spi {
>> +        #address-cells = <1>;
>> +        #size-cells = <0>;
>> +        num-cs = <4>;
>> +
>> +        sysc: system-controller@0 {
>> +            compatible = "amd,pensando-elbasr";
>> +            reg = <0>;
>> +            #address-cells = <1>;
>> +            #size-cells = <0>;
>> +            spi-max-frequency = <12000000>;
>> +
>> +            rstc: reset-controller@0 {
>> +                compatible = "amd,pensando-elbasr-reset";
>> +                reg = <0>;
> What does 0 represent here? A register address within 'elbasr' device?

Removed, I recall a check threw a warning or error without reg.

> Why do you need a child node for this? Are there other sub-devices and
> your binding is incomplete? Just put '#reset-cells' in the parent.

Without a reset-controller node and booting the function 
__of_reset_control_get(...) fails to find a match in the list here

         list_for_each_entry(r, &reset_controller_list, list) {
                 if (args.np == r->of_node) {
                         rcdev = r;
                         break;
                 }
         }

where in sdhci_cdns_probe(...) this lookup fails

         priv->rst_hw = devm_reset_control_get_optional_exclusive(dev, 
"hw");

which results in a non-functioning mmc hardware reset.


>> +                #reset-cells = <1>;
>> +            };
>> +        };
>> +
>> +        i2c1: i2c@1 {
>> +            compatible = "amd,pensando-elbasr";
> You can't reuse the same compatible to represent different things.


Changed to system-controller@1 and adjusted description above


>> +            reg = <1>;
>> +            spi-max-frequency = <12000000>;
>> +        };
>> +
>> +        i2c2: i2c@2 {
>> +            compatible = "amd,pensando-elbasr";
> As this is a Lattice RD1173, I would expect a compatible based on that.
>

Same as above, changed this to system-controller@2


>> +            reg = <2>;
>> +            spi-max-frequency = <12000000>;
>> +            interrupt-parent = <&porta>;
>> +            interrupts = <0 IRQ_TYPE_LEVEL_LOW>;
>> +        };
>> +
>> +        flash@3 {
>> +            compatible = "amd,pensando-elbasr";
> Isn't this a flash device?


A userspace utility understands how to program this internal flash.  
Changed to system-controller@3

Regards,
Brad