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SubjectRE: [PATCH v1 2/3] dt-bindings: riscv: convert plic bindings to json-schema
Date
Hello Rob,

> -----Original Message-----
> From: Rob Herring <robh@kernel.org>
> Sent: Wednesday, September 23, 2020 2:04 AM
> To: Sagar Kadam <sagar.kadam@openfive.com>
> Cc: linux-pwm@vger.kernel.org; linux-kernel@vger.kernel.org; linux-
> riscv@lists.infradead.org; devicetree@vger.kernel.org; linux-
> clk@vger.kernel.org; mturquette@baylibre.com; sboyd@kernel.org; Paul
> Walmsley ( Sifive) <paul.walmsley@sifive.com>; palmer@dabbelt.com;
> tglx@linutronix.de; jason@lakedaemon.net; maz@kernel.org;
> thierry.reding@gmail.com; u.kleine-koenig@pengutronix.de;
> lee.jones@linaro.org; aou@eecs.berkeley.edu; Yash Shah
> <yash.shah@openfive.com>
> Subject: Re: [PATCH v1 2/3] dt-bindings: riscv: convert plic bindings to json-
> schema
>
> [External Email] Do not click links or attachments unless you recognize the
> sender and know the content is safe
>
> On Thu, Sep 10, 2020 at 04:14:03PM +0530, Sagar Kadam wrote:
> > Convert device tree bindings for SiFive's PLIC to YAML format
> >
> > Signed-off-by: Sagar Kadam <sagar.kadam@sifive.com>
> > ---
> > .../interrupt-controller/sifive,plic-1.0.0.txt | 58 -----------
> > .../interrupt-controller/sifive,plic-1.0.0.yaml | 107
> +++++++++++++++++++++
> > 2 files changed, 107 insertions(+), 58 deletions(-)
> > delete mode 100644 Documentation/devicetree/bindings/interrupt-
> controller/sifive,plic-1.0.0.txt
> > create mode 100644 Documentation/devicetree/bindings/interrupt-
> controller/sifive,plic-1.0.0.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/interrupt-
> controller/sifive,plic-1.0.0.txt
> b/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-
> 1.0.0.txt
> > deleted file mode 100644
> > index 6adf7a6..0000000
> > --- a/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-
> 1.0.0.txt
> > +++ /dev/null
> > @@ -1,58 +0,0 @@
> > -SiFive Platform-Level Interrupt Controller (PLIC)
> > --------------------------------------------------
> > -
> > -SiFive SOCs include an implementation of the Platform-Level Interrupt
> Controller
> > -(PLIC) high-level specification in the RISC-V Privileged Architecture
> > -specification. The PLIC connects all external interrupts in the system to all
> > -hart contexts in the system, via the external interrupt source in each hart.
> > -
> > -A hart context is a privilege mode in a hardware execution thread. For
> example,
> > -in an 4 core system with 2-way SMT, you have 8 harts and probably at
> least two
> > -privilege modes per hart; machine mode and supervisor mode.
> > -
> > -Each interrupt can be enabled on per-context basis. Any context can claim
> > -a pending enabled interrupt and then release it once it has been handled.
> > -
> > -Each interrupt has a configurable priority. Higher priority interrupts are
> > -serviced first. Each context can specify a priority threshold. Interrupts
> > -with priority below this threshold will not cause the PLIC to raise its
> > -interrupt line leading to the context.
> > -
> > -While the PLIC supports both edge-triggered and level-triggered interrupts,
> > -interrupt handlers are oblivious to this distinction and therefore it is not
> > -specified in the PLIC device-tree binding.
> > -
> > -While the RISC-V ISA doesn't specify a memory layout for the PLIC, the
> > -"sifive,plic-1.0.0" device is a concrete implementation of the PLIC that
> > -contains a specific memory layout, which is documented in chapter 8 of
> the
> > -SiFive U5 Coreplex Series Manual <https://static.dev.sifive.com/U54-MC-
> RVCoreIP.pdf>.
> > -
> > -Required properties:
> > -- compatible : "sifive,plic-1.0.0" and a string identifying the actual
> > - detailed implementation in case that specific bugs need to be worked
> around.
> > -- #address-cells : should be <0> or more.
> > -- #interrupt-cells : should be <1> or more.
> > -- interrupt-controller : Identifies the node as an interrupt controller.
> > -- reg : Should contain 1 register range (address and length).
> > -- interrupts-extended : Specifies which contexts are connected to the PLIC,
> > - with "-1" specifying that a context is not present. Each node pointed
> > - to should be a riscv,cpu-intc node, which has a riscv node as parent.
> > -- riscv,ndev: Specifies how many external interrupts are supported by
> > - this controller.
> > -
> > -Example:
> > -
> > - plic: interrupt-controller@c000000 {
> > - #address-cells = <0>;
> > - #interrupt-cells = <1>;
> > - compatible = "sifive,plic-1.0.0", "sifive,fu540-c000-plic";
> > - interrupt-controller;
> > - interrupts-extended = <
> > - &cpu0-intc 11
> > - &cpu1-intc 11 &cpu1-intc 9
> > - &cpu2-intc 11 &cpu2-intc 9
> > - &cpu3-intc 11 &cpu3-intc 9
> > - &cpu4-intc 11 &cpu4-intc 9>;
> > - reg = <0xc000000 0x4000000>;
> > - riscv,ndev = <10>;
> > - };
> > diff --git a/Documentation/devicetree/bindings/interrupt-
> controller/sifive,plic-1.0.0.yaml
> b/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-
> 1.0.0.yaml
> > new file mode 100644
> > index 0000000..95c8c85
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-
> 1.0.0.yaml
> > @@ -0,0 +1,107 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +# Copyright (C) 2020 SiFive, Inc.
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/interrupt-controller/sifive,plic-
> 1.0.0.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: SiFive Platform-Level Interrupt Controller (PLIC)
> > +
> > +description:
> > + SiFive SOCs include an implementation of the Platform-Level Interrupt
> Controller
> > + (PLIC) high-level specification in the RISC-V Privileged Architecture
> > + specification. The PLIC connects all external interrupts in the system to all
> > + hart contexts in the system, via the external interrupt source in each
> hart.
> > +
> > + A hart context is a privilege mode in a hardware execution thread. For
> example,
> > + in an 4 core system with 2-way SMT, you have 8 harts and probably at
> least two
> > + privilege modes per hart; machine mode and supervisor mode.
> > +
> > + Each interrupt can be enabled on per-context basis. Any context can
> claim
> > + a pending enabled interrupt and then release it once it has been
> handled.
> > +
> > + Each interrupt has a configurable priority. Higher priority interrupts are
> > + serviced first. Each context can specify a priority threshold. Interrupts
> > + with priority below this threshold will not cause the PLIC to raise its
> > + interrupt line leading to the context.
> > +
> > + While the PLIC supports both edge-triggered and level-triggered
> interrupts,
> > + interrupt handlers are oblivious to this distinction and therefore it is not
> > + specified in the PLIC device-tree binding.
> > +
> > + While the RISC-V ISA doesn't specify a memory layout for the PLIC, the
> > + "sifive,plic-1.0.0" device is a concrete implementation of the PLIC that
> > + contains a specific memory layout, which is documented in chapter 8 of
> the
> > + SiFive U5 Coreplex Series Manual <https://static.dev.sifive.com/U54-MC-
> RVCoreIP.pdf>.
> > +
> > +maintainers:
> > + - Sagar Kadam <sagar.kadam@sifive.com>
> > + - Paul Walmsley <paul.walmsley@sifive.com>
> > + - Palmer Dabbelt <palmer@dabbelt.com>
> > +
> > +allOf:
> > + - $ref: /schemas/interrupt-controller.yaml#
>
> Don't need this. It gets selected matching on node name.
>
Thanks for your suggestions. I will incorporate your suggestions and send the v2.
> > +
> > +properties:
> > + compatible:
> > + items:
> > + - const: sifive,plic-1.0.0
> > + - const: sifive,fu540-c000-plic
>
> Somehow these ended up in the wrong order. Should be most specific to
> least specific.
>
Yes, will rectify this.
> > +
> > + description:
> > + Should be "sifive,plic-1.0.0" and a string identifying the actual
> > + detailed implementation in case that specific bugs need to be worked
> around.
>
> Drop this.
>
> > +
> > + reg:
> > + maxItems: 1
> > + description: Should contain 1 register range (address and length).
>
> Drop this. The schema says this...
>
> > +
> > + '#address-cells':
> > + const: 0
> > + description: Should be <0> or more.
>
> Drop. 'or more' is wrong. If there's a case with more, it will need to
> be documented.
>
> > +
> > + '#interrupt-cells':
> > + const: 1
> > + description: Should be <1> or more.
>
> Same here.
>
Okay.
Will remove as suggested above

Thanks & BR,
Sagar

> > +
> > + interrupt-controller: true
> > +
> > + interrupts-extended:
> > + minItems: 1
> > + description:
> > + Specifies which contexts are connected to the PLIC, with "-1" specifying
> > + that a context is not present. Each node pointed to should be a
> > + riscv,cpu-intc node, which has a riscv node as parent.
> > +
> > + riscv,ndev:
> > + $ref: "/schemas/types.yaml#/definitions/uint32"
> > + description:
> > + Specifies how many external interrupts are supported by this
> controller.
> > +
> > +required:
> > + - compatible
> > + - '#address-cells'
> > + - '#interrupt-cells'
> > + - interrupt-controller
> > + - reg
> > + - interrupts-extended
> > + - riscv,ndev
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > + - |
> > + plic: interrupt-controller@c000000 {
> > + #address-cells = <0>;
> > + #interrupt-cells = <1>;
> > + compatible = "sifive,plic-1.0.0", "sifive,fu540-c000-plic";
> > + interrupt-controller;
> > + interrupts-extended = <
> > + &cpu0_intc 11
> > + &cpu1_intc 11 &cpu1_intc 9
> > + &cpu2_intc 11 &cpu2_intc 9
> > + &cpu3_intc 11 &cpu3_intc 9
> > + &cpu4_intc 11 &cpu4_intc 9>;
> > + reg = <0xc000000 0x4000000>;
> > + riscv,ndev = <10>;
> > + };
> > --
> > 2.7.4
> >

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