[PATCH 1/6] dt-bindings: Add Baikal-T1 AXI-bus EHB dts bindings file

[PATCH 1/6] dt-bindings: Add Baikal-T1 AXI-bus EHB dts bindings file

[Sergey.Semin]

From: Serge Semin <Sergey.Semin@baikalelectronics.ru>

This is a specific block embedded into the Baikal-T1 SoC, which is
dedicated to detect AXI-bus protocol errors. So the dts node just
needs to have the "be,bt1-axi-ehb" compatible string, MMIO registers
and interrupts properties declared.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>
Cc: soc@kernel.org
---
 .../soc/baikal-t1/be,bt1-axi-ehb.yaml         | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-axi-ehb.yaml

diff --git a/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-axi-ehb.yaml b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-axi-ehb.yaml
new file mode 100644
index 000000000000..f0deeb8f261c
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-axi-ehb.yaml
@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2019 - 2020 BAIKAL ELECTRONICS, JSC
+#
+# Baikal-T1 AXI-bus Errors Handler Block Device Tree Bindings.
+#
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/baikal-t1/be,bt1-axi-ehb.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Baikal-T1 AXI-bus Errors Handler Block
+
+maintainers:
+  - Serge Semin <fancer.lancer@gmail.com>
+
+description: |
+  AXI3-bus is the main communication bus connecting all high-speed peripheral
+  IP-cores with RAM controller and with MIPS P5600 cores. Traffic arbitration
+  is done by means of Main Interconnect routing IO request from one block to
+  another. In case of any protocol error, device not responding an IRQ is
+  raised and a faulty situation is reported to the AXI EHB described by this
+  bindings.
+
+properties:
+  compatible:
+    const: be,bt1-axi-ehb
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/mips-gic.h>
+
+    axi_ehb: ehb@1F04D110 {
+      compatible = "be,bt1-axi-ehb";
+      reg = <0x1F04D110 0x008>;
+
+      interrupts = <GIC_SHARED 127 IRQ_TYPE_LEVEL_HIGH>;
+    };
+...
-- 
2.25.1

[PATCH 2/6] dt-bindings: Add Baikal-T1 APB-bus EHB dts bindings file

[Sergey.Semin]

From: Serge Semin <Sergey.Semin@baikalelectronics.ru>

This is a specific block embedded into the Baikal-T1 SoC, which is
dedicated to detect APB-bus protocol errors and tune the peripheral
access timeout. So the dts bindings implies that corresponding dts
node would be equipped with "be,bt1-apb-ehb" compatible string, MMIO
region of registers space and of space with no device mapped,
interrupts property and with an APB-reference clock handler.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>
Cc: soc@kernel.org
---
 .../soc/baikal-t1/be,bt1-apb-ehb.yaml         | 66 +++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.yaml

diff --git a/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.yaml b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.yaml
new file mode 100644
index 000000000000..e262aead2fb5
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.yaml
@@ -0,0 +1,66 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2019 - 2020 BAIKAL ELECTRONICS, JSC
+#
+# Baikal-T1 APB-bus Errors Handler Block Device Tree Bindings.
+#
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/baikal-t1/be,bt1-apb-ehb.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Baikal-T1 APB-bus Errors Handler Block
+
+maintainers:
+  - Serge Semin <fancer.lancer@gmail.com>
+
+description: |
+  Configuration registers of Baikal-T1 SoC peripheral interfaces are accessed
+  by means of the APB-bus. In case of any APB protocol collisions, slave device
+  not responding on timeout an IRQ is raised with an erroneous address reported
+  to the APB terminator (EHB) sub-block described by this bindings file.
+
+properties:
+  compatible:
+    const: be,bt1-apb-ehb
+
+  reg:
+    items:
+      - description: APB EHB MMIO registers.
+      - description: APB MMIO region with no any device mapped.
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    description: APB reference clock.
+    maxItems: 1
+
+  clock-names:
+    const: ref
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/mips-gic.h>
+    #include <dt-bindings/clock/bt1-ccu.h>
+
+    apb_ehb: ehb@1F059000 {
+      compatible = "be,bt1-apb-ehb";
+      reg = <0x1F059000 0x1000>,
+            <0x1D000000 0x2040000>;
+
+      interrupts = <GIC_SHARED 16 IRQ_TYPE_LEVEL_HIGH>;
+
+      clocks = <&ccu_sys CCU_SYS_APB_CLK>;
+      clock-names = "ref";
+    };
+...
-- 
2.25.1

Re: [PATCH 2/6] dt-bindings: Add Baikal-T1 APB-bus EHB dts bindings file

[Rob Herring]

On Fri, 6 Mar 2020 16:07:17 +0300, <Sergey.Semin@baikalelectronics.ru> wrote:
> From: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> 
> This is a specific block embedded into the Baikal-T1 SoC, which is
> dedicated to detect APB-bus protocol errors and tune the peripheral
> access timeout. So the dts bindings implies that corresponding dts
> node would be equipped with "be,bt1-apb-ehb" compatible string, MMIO
> region of registers space and of space with no device mapped,
> interrupts property and with an APB-reference clock handler.
> 
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Paul Burton <paulburton@kernel.org>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Olof Johansson <olof@lixom.net>
> Cc: soc@kernel.org
> ---
>  .../soc/baikal-t1/be,bt1-apb-ehb.yaml         | 66 +++++++++++++++++++
>  1 file changed, 66 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.yaml
> 

My bot found errors running 'make dt_binding_check' on your patch:

Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.example.dts:18:18: fatal error: dt-bindings/clock/bt1-ccu.h: No such file or directory
         #include <dt-bindings/clock/bt1-ccu.h>
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
scripts/Makefile.lib:311: recipe for target 'Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.example.dt.yaml' failed
make[1]: *** [Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-apb-ehb.example.dt.yaml] Error 1
Makefile:1262: recipe for target 'dt_binding_check' failed
make: *** [dt_binding_check] Error 2

See https://patchwork.ozlabs.org/patch/1250282
Please check and re-submit.

[PATCH 3/6] dt-bindings: Add Baikal-T1 L2-cache Control Block dts bindings file

[Sergey.Semin]

From: Serge Semin <Sergey.Semin@baikalelectronics.ru>

There is a single register provided by the SoC system controller,
which can be used to tune the L2-cache up. It only provides a way
to change the L2-RAM access latencies. So aside from the MMIO region
with that setting and "be,bt1-l2-ctl" compatible string the device
node can be optionally equipped with the properties of Tag/Data/WS
latencies.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>
Cc: soc@kernel.org
---
 .../bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml | 108 ++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml

diff --git a/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml
new file mode 100644
index 000000000000..8769b3fa517c
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml
@@ -0,0 +1,108 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
+#
+# Baikal-T1 L2-cache Control Block Device Tree Bindings.
+#
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/baikal-t1/be,bt1-l2-ctl.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Baikal-T1 L2-cache Control Block
+
+maintainers:
+  - Serge Semin <fancer.lancer@gmail.com>
+
+description: |
+  Baikal-T1 exposes a few settings to tune the MIPS P5600 CM2 L2-cache
+  performance up. In particular it's possible to change the Tag, Data and
+  Way-select RAM access latencies. This bindings file describes the system
+  controller block, which provides an interface to set the tuning up.
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: syscon
+    then:
+      $ref: ../../mfd/syscon.yaml#
+    else:
+      properties:
+        reg-io-width: false
+
+        little-endian: false
+
+properties:
+  compatible:
+    oneOf:
+      - description: P5600 CM2 L2-cache RAM external configuration block.
+        const: be,bt1-l2-ctl
+      - description: P5600 CM2 L2-cache RAM system controller block.
+        items:
+          - const: be,bt1-l2-ctl
+          - const: syscon
+
+  reg:
+    description: MMIO register with MIPS P5600 CM2 L2-cache RAM settings.
+    maxItems: 1
+
+  be,l2-ws-latency:
+    description: Cycles of latency for Way-select RAM accesses.
+    default: 0
+    allOf:
+      - $ref: /schemas/types.yaml#/definitions/uint32
+      - minimum: 0
+        maximum: 3
+
+  be,l2-tag-latency:
+    description: Cycles of latency for Tag RAM accesses.
+    default: 0
+    allOf:
+      - $ref: /schemas/types.yaml#/definitions/uint32
+      - minimum: 0
+        maximum: 3
+
+  be,l2-data-latency:
+    description: Cycles of latency for Data RAM accesses.
+    default: 1
+    allOf:
+      - $ref: /schemas/types.yaml#/definitions/uint32
+      - minimum: 0
+        maximum: 3
+
+  reg-io-width:
+    const: 4
+
+  little-endian: true
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+
+examples:
+  - |
+    l2_ctl1: l2@1F04D028 {
+      compatible = "be,bt1-l2-ctl";
+      reg = <0x1F04D028 0x004>;
+
+      be,l2-ws-latency = <0>;
+      be,l2-tag-latency = <0>;
+      be,l2-data-latency = <1>;
+    };
+  - |
+    l2_ctl2: l2@1F04D028 {
+      compatible = "be,bt1-l2-ctl", "syscon";
+      reg = <0x1F04D028 0x004>;
+
+      be,l2-ws-latency = <0>;
+      be,l2-tag-latency = <0>;
+      be,l2-data-latency = <1>;
+
+      little-endian;
+      reg-io-width = <4>;
+    };
+...
-- 
2.25.1

Re: [PATCH 3/6] dt-bindings: Add Baikal-T1 L2-cache Control Block dts bindings file

[Rob Herring]

On Fri, Mar 06, 2020 at 04:07:18PM +0300, Sergey.Semin@baikalelectronics.ru wrote:
> From: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> 
> There is a single register provided by the SoC system controller,
> which can be used to tune the L2-cache up. It only provides a way
> to change the L2-RAM access latencies. So aside from the MMIO region
> with that setting and "be,bt1-l2-ctl" compatible string the device
> node can be optionally equipped with the properties of Tag/Data/WS
> latencies.
> 
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Paul Burton <paulburton@kernel.org>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Olof Johansson <olof@lixom.net>
> Cc: soc@kernel.org
> ---
>  .../bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml | 108 ++++++++++++++++++
>  1 file changed, 108 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml
> 
> diff --git a/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml
> new file mode 100644
> index 000000000000..8769b3fa517c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml
> @@ -0,0 +1,108 @@
> +# SPDX-License-Identifier: GPL-2.0

Dual license

> +#
> +# Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
> +#
> +# Baikal-T1 L2-cache Control Block Device Tree Bindings.
> +#
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/soc/baikal-t1/be,bt1-l2-ctl.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Baikal-T1 L2-cache Control Block
> +
> +maintainers:
> +  - Serge Semin <fancer.lancer@gmail.com>
> +
> +description: |
> +  Baikal-T1 exposes a few settings to tune the MIPS P5600 CM2 L2-cache
> +  performance up. In particular it's possible to change the Tag, Data and
> +  Way-select RAM access latencies. This bindings file describes the system
> +  controller block, which provides an interface to set the tuning up.
> +
> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: syscon
> +    then:
> +      $ref: ../../mfd/syscon.yaml#
> +    else:
> +      properties:
> +        reg-io-width: false
> +
> +        little-endian: false
> +
> +properties:
> +  compatible:
> +    oneOf:
> +      - description: P5600 CM2 L2-cache RAM external configuration block.
> +        const: be,bt1-l2-ctl
> +      - description: P5600 CM2 L2-cache RAM system controller block.
> +        items:
> +          - const: be,bt1-l2-ctl
> +          - const: syscon

Why is this conditional? Different h/w?

> +
> +  reg:
> +    description: MMIO register with MIPS P5600 CM2 L2-cache RAM settings.

You can drop this.

> +    maxItems: 1
> +
> +  be,l2-ws-latency:
> +    description: Cycles of latency for Way-select RAM accesses.
> +    default: 0
> +    allOf:
> +      - $ref: /schemas/types.yaml#/definitions/uint32
> +      - minimum: 0
> +        maximum: 3

These should be at the same level as 'default' or default moved here (I 
prefer the former). IOW, only $ref has to be under 'allOf'.

> +
> +  be,l2-tag-latency:
> +    description: Cycles of latency for Tag RAM accesses.
> +    default: 0
> +    allOf:
> +      - $ref: /schemas/types.yaml#/definitions/uint32
> +      - minimum: 0
> +        maximum: 3
> +
> +  be,l2-data-latency:
> +    description: Cycles of latency for Data RAM accesses.
> +    default: 1
> +    allOf:
> +      - $ref: /schemas/types.yaml#/definitions/uint32
> +      - minimum: 0
> +        maximum: 3
> +
> +  reg-io-width:
> +    const: 4
> +
> +  little-endian: true
> +
> +additionalProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +
> +examples:
> +  - |
> +    l2_ctl1: l2@1F04D028 {

lowercase hex.

> +      compatible = "be,bt1-l2-ctl";
> +      reg = <0x1F04D028 0x004>;
> +
> +      be,l2-ws-latency = <0>;
> +      be,l2-tag-latency = <0>;
> +      be,l2-data-latency = <1>;
> +    };
> +  - |
> +    l2_ctl2: l2@1F04D028 {
> +      compatible = "be,bt1-l2-ctl", "syscon";
> +      reg = <0x1F04D028 0x004>;
> +
> +      be,l2-ws-latency = <0>;
> +      be,l2-tag-latency = <0>;
> +      be,l2-data-latency = <1>;
> +
> +      little-endian;
> +      reg-io-width = <4>;
> +    };
> +...
> -- 
> 2.25.1
> 

Re: [PATCH 3/6] dt-bindings: Add Baikal-T1 L2-cache Control Block dts bindings file

[Sergey Semin]

On Thu, Mar 12, 2020 at 04:23:35PM -0500, Rob Herring wrote:
> On Fri, Mar 06, 2020 at 04:07:18PM +0300, Sergey.Semin@baikalelectronics.ru wrote:
> > From: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> > 
> > There is a single register provided by the SoC system controller,
> > which can be used to tune the L2-cache up. It only provides a way
> > to change the L2-RAM access latencies. So aside from the MMIO region
> > with that setting and "be,bt1-l2-ctl" compatible string the device
> > node can be optionally equipped with the properties of Tag/Data/WS
> > latencies.
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> > Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
> > Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> > Cc: Paul Burton <paulburton@kernel.org>
> > Cc: Ralf Baechle <ralf@linux-mips.org>
> > Cc: Arnd Bergmann <arnd@arndb.de>
> > Cc: Olof Johansson <olof@lixom.net>
> > Cc: soc@kernel.org
> > ---
> >  .../bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml | 108 ++++++++++++++++++
> >  1 file changed, 108 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml
> > new file mode 100644
> > index 000000000000..8769b3fa517c
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/soc/baikal-t1/be,bt1-l2-ctl.yaml
> > @@ -0,0 +1,108 @@
> > +# SPDX-License-Identifier: GPL-2.0
> 
> Dual license

Ok.

> 
> > +#
> > +# Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
> > +#
> > +# Baikal-T1 L2-cache Control Block Device Tree Bindings.
> > +#
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/soc/baikal-t1/be,bt1-l2-ctl.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Baikal-T1 L2-cache Control Block
> > +
> > +maintainers:
> > +  - Serge Semin <fancer.lancer@gmail.com>
> > +
> > +description: |
> > +  Baikal-T1 exposes a few settings to tune the MIPS P5600 CM2 L2-cache
> > +  performance up. In particular it's possible to change the Tag, Data and
> > +  Way-select RAM access latencies. This bindings file describes the system
> > +  controller block, which provides an interface to set the tuning up.
> > +
> > +allOf:
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: syscon
> > +    then:
> > +      $ref: ../../mfd/syscon.yaml#
> > +    else:
> > +      properties:
> > +        reg-io-width: false
> > +
> > +        little-endian: false
> > +
> > +properties:
> > +  compatible:
> > +    oneOf:
> > +      - description: P5600 CM2 L2-cache RAM external configuration block.
> > +        const: be,bt1-l2-ctl
> > +      - description: P5600 CM2 L2-cache RAM system controller block.
> > +        items:
> > +          - const: be,bt1-l2-ctl
> > +          - const: syscon
> 
> Why is this conditional? Different h/w?
> 

Seeing the config register has got a few other CPU parameters to tune
I meant to have both syscon and syscon-less compatible nodes supported
For the same reason there is "allOf" with "syscon.yaml" reference above.

This P5600 CM2 L2-Cach RAM setting is a part of the Baikal-T1 System
Control Module, in particular the register lives someplace amongst Clock
Control Unit and System-specific settings. Seeing the clock and
system-specific parameters are almost always redistributed to a
dedicated registers set, in my first System Control Module DT node design
I was going to split the functionality up into the dedicated sub-nodes.
If there are some mixed parameters declared in the corresponding
registers set, I marked these nodes with additional "syscon". I
thoroughly described that design in RFC: https://lkml.org/lkml/2020/3/22/393
sent To: you.

Seeing there are others indirectly related to the System Controller DT node
design issues I've been addressed in the framework of other patchsets, I
also suggested an alternative design in that RFC text. So should you have
any comments, please send your response right there. I am currently in a bit
of frustration, since noone has sent any comments to the RFC, which stops me
from moving on with fixing the patchsets issues. Though I am pretty sure,
that the alternative design would be better accepted by you and community,
so if no comments pop up in the RFC soon, I'll start implementing it.
The alternative solution "/* System Controller DT Nodes II */" in the
RFC includes having a common "syscon"-compatible node representing the
Baikal-T1 System Controller, while sub-nodes like Clocks Control Units and this
L2-cache RAM control block would import a regmap from that "syscon"
(using a standard syscon_node_to_regmap()-like method). This will solve a
multiple issues raised in others patchsets and the problem you noted here.

Please also note, that following Arnd Bergmann suggestion, I'll move
this driver to the drivers/memory subsystem. So the binding file will be
also moved to Documentation/devicetree/bindings/memory-controllers.
Similarly the ehb-drivers and bindings will be moved to the drivers/bus
and Documentation/devicetree/bindings/bus/ directories respectively.

> > +
> > +  reg:
> > +    description: MMIO register with MIPS P5600 CM2 L2-cache RAM settings.
> 
> You can drop this.

Ok.

> 
> > +    maxItems: 1
> > +
> > +  be,l2-ws-latency:
> > +    description: Cycles of latency for Way-select RAM accesses.
> > +    default: 0
> > +    allOf:
> > +      - $ref: /schemas/types.yaml#/definitions/uint32
> > +      - minimum: 0
> > +        maximum: 3
> 
> These should be at the same level as 'default' or default moved here (I 
> prefer the former). IOW, only $ref has to be under 'allOf'.

Ok.

> 
> > +
> > +  be,l2-tag-latency:
> > +    description: Cycles of latency for Tag RAM accesses.
> > +    default: 0
> > +    allOf:
> > +      - $ref: /schemas/types.yaml#/definitions/uint32
> > +      - minimum: 0
> > +        maximum: 3
> > +
> > +  be,l2-data-latency:
> > +    description: Cycles of latency for Data RAM accesses.
> > +    default: 1
> > +    allOf:
> > +      - $ref: /schemas/types.yaml#/definitions/uint32
> > +      - minimum: 0
> > +        maximum: 3
> > +
> > +  reg-io-width:
> > +    const: 4
> > +
> > +  little-endian: true
> > +
> > +additionalProperties: false
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +examples:
> > +  - |
> > +    l2_ctl1: l2@1F04D028 {
> 
> lowercase hex.

Ok. I'll do this to the next example case as well.

Regards,
-Sergey

> 
> > +      compatible = "be,bt1-l2-ctl";
> > +      reg = <0x1F04D028 0x004>;
> > +
> > +      be,l2-ws-latency = <0>;
> > +      be,l2-tag-latency = <0>;
> > +      be,l2-data-latency = <1>;
> > +    };
> > +  - |
> > +    l2_ctl2: l2@1F04D028 {
> > +      compatible = "be,bt1-l2-ctl", "syscon";
> > +      reg = <0x1F04D028 0x004>;
> > +
> > +      be,l2-ws-latency = <0>;
> > +      be,l2-tag-latency = <0>;
> > +      be,l2-data-latency = <1>;
> > +
> > +      little-endian;
> > +      reg-io-width = <4>;
> > +    };
> > +...
> > -- 
> > 2.25.1
> >