[16/21] dt-bindings: ata: ahci: Add DWC AHCI SATA controller DT schema

Synopsys AHCI SATA controller is mainly compatible with the generic AHCI
SATA controller except a few peculiarities and the platform environment
requirements. In particular it can have one or two reference clocks to
feed up its AXI/AHB interface and SATA PHYs domain and at least one reset
control for the application clock domain. In addition to that the DMA
interface of each port can be tuned up to work with the predefined maximum
data chunk size. Note unlike generic AHCI controller DWC AHCI can't have
more than 8 ports. All of that is reflected in the new DWC AHCI SATA
device DT binding.

Note the DWC AHCI SATA controller DT-schema has been created in a way so
to be reused for the vendor-specific DT-schemas. One of which we are about
to introduce.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
---
 .../bindings/ata/snps,dwc-ahci.yaml           | 121 ++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/ata/snps,dwc-ahci.yaml

On Thu, Mar 24, 2022 at 03:16:23AM +0300, Serge Semin wrote:
> Synopsys AHCI SATA controller is mainly compatible with the generic AHCI
> SATA controller except a few peculiarities and the platform environment
> requirements. In particular it can have one or two reference clocks to
> feed up its AXI/AHB interface and SATA PHYs domain and at least one reset
> control for the application clock domain. In addition to that the DMA
> interface of each port can be tuned up to work with the predefined maximum
> data chunk size. Note unlike generic AHCI controller DWC AHCI can't have
> more than 8 ports. All of that is reflected in the new DWC AHCI SATA
> device DT binding.
> 
> Note the DWC AHCI SATA controller DT-schema has been created in a way so
> to be reused for the vendor-specific DT-schemas. One of which we are about
> to introduce.
> 
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> ---
>  .../bindings/ata/snps,dwc-ahci.yaml           | 121 ++++++++++++++++++
>  1 file changed, 121 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/ata/snps,dwc-ahci.yaml
> 
> diff --git a/Documentation/devicetree/bindings/ata/snps,dwc-ahci.yaml b/Documentation/devicetree/bindings/ata/snps,dwc-ahci.yaml
> new file mode 100644
> index 000000000000..b443154b63aa
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/ata/snps,dwc-ahci.yaml
> @@ -0,0 +1,121 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/ata/snps,dwc-ahci.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Synopsys DWC AHCI SATA controller
> +
> +maintainers:
> +  - Serge Semin <fancer.lancer@gmail.com>
> +
> +description: |
> +  This document defines device tree bindings for the Synopsys DWC
> +  implementation of the AHCI SATA controller.
> +
> +allOf:
> +  - $ref: ahci-common.yaml#
> +
> +properties:
> +  compatible:
> +    oneOf:
> +      - description: Synopsys AHCI SATA-compatible devices
> +        contains:
> +          const: snps,dwc-ahci
> +      - description: SPEAr1340 AHCI SATA device
> +        const: snps,spear-ahci
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  clocks:
> +    description:
> +      Basic DWC AHCI SATA clock sources like application AXI/AHB BIU clock
> +      and embedded PHYs reference clock together with vendor-specific set
> +      of clocks.
> +    minItems: 1
> +    maxItems: 4
> +
> +  clock-names:
> +    contains:
> +      anyOf:
> +        - description: Application AXI/AHB BIU clock source
> +          enum:
> +            - aclk
> +            - sata
> +        - description: SATA Ports reference clock
> +          enum:
> +            - ref
> +            - sata_ref
> +
> +  resets:
> +    description:
> +      At least basic core and application clock domains reset is normally
> +      supported by the DWC AHCI SATA controller. Some platform specific
> +      clocks can be also specified though.
> +
> +  reset-names:
> +    contains:
> +      description: Core and application clock domains reset control
> +      const: arst
> +
> +patternProperties:
> +  "^sata-port@[0-9a-e]$":
> +    type: object
> +
> +    properties:
> +      reg:
> +        minimum: 0
> +        maximum: 7
> +
> +      snps,tx-ts-max:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        description: Maximal size of Tx DMA transactions in FIFO words
> +        minimum: 1
> +        maximum: 1024
> +
> +      snps,rx-ts-max:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        description: Maximal size of Rx DMA transactions in FIFO words
> +        minimum: 1
> +        maximum: 1024

Are you reading these somewhere? 

Only powers of 2 are valid. (Guess what Calxeda's controller uses.)

Rob

On Thu, Mar 31, 2022 at 07:06:27PM -0500, Rob Herring wrote:
> On Thu, Mar 24, 2022 at 03:16:23AM +0300, Serge Semin wrote:
> > Synopsys AHCI SATA controller is mainly compatible with the generic AHCI
> > SATA controller except a few peculiarities and the platform environment
> > requirements. In particular it can have one or two reference clocks to
> > feed up its AXI/AHB interface and SATA PHYs domain and at least one reset
> > control for the application clock domain. In addition to that the DMA
> > interface of each port can be tuned up to work with the predefined maximum
> > data chunk size. Note unlike generic AHCI controller DWC AHCI can't have
> > more than 8 ports. All of that is reflected in the new DWC AHCI SATA
> > device DT binding.
> > 
> > Note the DWC AHCI SATA controller DT-schema has been created in a way so
> > to be reused for the vendor-specific DT-schemas. One of which we are about
> > to introduce.
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> > ---
> >  .../bindings/ata/snps,dwc-ahci.yaml           | 121 ++++++++++++++++++
> >  1 file changed, 121 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/ata/snps,dwc-ahci.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/ata/snps,dwc-ahci.yaml b/Documentation/devicetree/bindings/ata/snps,dwc-ahci.yaml
> > new file mode 100644
> > index 000000000000..b443154b63aa
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/ata/snps,dwc-ahci.yaml
> > @@ -0,0 +1,121 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/ata/snps,dwc-ahci.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Synopsys DWC AHCI SATA controller
> > +
> > +maintainers:
> > +  - Serge Semin <fancer.lancer@gmail.com>
> > +
> > +description: |
> > +  This document defines device tree bindings for the Synopsys DWC
> > +  implementation of the AHCI SATA controller.
> > +
> > +allOf:
> > +  - $ref: ahci-common.yaml#
> > +
> > +properties:
> > +  compatible:
> > +    oneOf:
> > +      - description: Synopsys AHCI SATA-compatible devices
> > +        contains:
> > +          const: snps,dwc-ahci
> > +      - description: SPEAr1340 AHCI SATA device
> > +        const: snps,spear-ahci
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    description:
> > +      Basic DWC AHCI SATA clock sources like application AXI/AHB BIU clock
> > +      and embedded PHYs reference clock together with vendor-specific set
> > +      of clocks.
> > +    minItems: 1
> > +    maxItems: 4
> > +
> > +  clock-names:
> > +    contains:
> > +      anyOf:
> > +        - description: Application AXI/AHB BIU clock source
> > +          enum:
> > +            - aclk
> > +            - sata
> > +        - description: SATA Ports reference clock
> > +          enum:
> > +            - ref
> > +            - sata_ref
> > +
> > +  resets:
> > +    description:
> > +      At least basic core and application clock domains reset is normally
> > +      supported by the DWC AHCI SATA controller. Some platform specific
> > +      clocks can be also specified though.
> > +
> > +  reset-names:
> > +    contains:
> > +      description: Core and application clock domains reset control
> > +      const: arst
> > +
> > +patternProperties:
> > +  "^sata-port@[0-9a-e]$":
> > +    type: object
> > +
> > +    properties:
> > +      reg:
> > +        minimum: 0
> > +        maximum: 7
> > +
> > +      snps,tx-ts-max:
> > +        $ref: /schemas/types.yaml#/definitions/uint32
> > +        description: Maximal size of Tx DMA transactions in FIFO words
> > +        minimum: 1
> > +        maximum: 1024
> > +
> > +      snps,rx-ts-max:
> > +        $ref: /schemas/types.yaml#/definitions/uint32
> > +        description: Maximal size of Rx DMA transactions in FIFO words
> > +        minimum: 1
> > +        maximum: 1024
> 

> Are you reading these somewhere? 

Yes I do read them in the DWC AHCI driver and use ilog2() to get
the corresponding power of two value.

> 
> Only powers of 2 are valid. (Guess what Calxeda's controller uses.)

Right and is limited to be within [1; 1024]. Do you suggest to add a
respective comment in the description or just manually enumerate the
POW2 values? I don't believe there is a ready-to-use power-of-2 type in
the /schemas/types.yaml file. BTW what about adding one seeing there are
many cases where it could be useful?

-Sergey

> 
> Rob