linux-kernel - Re: [PATCH v2 02/12] of: add J-Core cpu bindings

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Date:	Mon, 23 May 2016 15:48:46 -0500
From:	Rob Herring <robh@...nel.org>
To:	Rich Felker <dalias@...c.org>
Cc:	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-sh@...r.kernel.org,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Mark Rutland <mark.rutland@....com>,
	Pawel Moll <pawel.moll@....com>
Subject: Re: [PATCH v2 02/12] of: add J-Core cpu bindings

On Fri, May 20, 2016 at 02:53:03AM +0000, Rich Felker wrote:
> Signed-off-by: Rich Felker <dalias@...c.org>
> ---
>  Documentation/devicetree/bindings/jcore/cpus.txt | 91 ++++++++++++++++++++++++
>  1 file changed, 91 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/jcore/cpus.txt
> 
> diff --git a/Documentation/devicetree/bindings/jcore/cpus.txt b/Documentation/devicetree/bindings/jcore/cpus.txt
> new file mode 100644
> index 0000000..00ef112
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/jcore/cpus.txt
> @@ -0,0 +1,91 @@
> +===================
> +J-Core cpu bindings
> +===================
> +
> +The J-Core processors are open source CPU cores that can be built as FPGA
> +soft cores or ASICs. The device tree is also responsible for describing the
> +cache controls and, for SMP configurations, all details of the SMP method,
> +as documented below.
> +
> +
> +---------------------
> +Top-level "cpus" node
> +---------------------
> +
> +Required properties:
> +
> +- #address-cells: Must be 1.
> +
> +- #size-cells: Must be 0.
> +
> +Optional properties:
> +
> +- enable-method: Required only for SMP systems. If present, must be
> +  "jcore,spin-table".
> +
> +
> +--------------------
> +Individual cpu nodes
> +--------------------
> +
> +Required properties:
> +
> +- device_type: Must be "cpu".
> +
> +- compatible: Must be "jcore,j2".

Okay to have this, but you should have compatible strings for specific 
core implementations. AIUI, J2 is just the ISA.

> +
> +- reg: Must be 0 on uniprocessor systems, or the sequential, zero-based
> +  hardware cpu id on SMP systems.
> +
> +Optional properties:
> +
> +- clock-frequency: Clock frequency of the cpu in Hz.
> +
> +- cpu-release-addr: Necessary only for secondary processors on SMP systems
> +  using the "jcore,spin-table" enable method. If present, must consist of
> +  two cells containing physical addresses. The first cell contains an
> +  address which, when written, unblocks the secondary cpu. The second cell
> +  contains an address from which the cpu will read its initial program
> +  counter when unblocked.
> +
> +
> +---------------------
> +Cache controller node
> +---------------------
> +
> +Required properties:
> +
> +- compatible: Must be "jcore,cache".

That's pretty generic...

> +
> +- reg: A memory range for the cache controller registers.

And standard cache properties? Are size, sets, ways, line size, etc. 
discoverable?

> +
> +
> +--------
> +IPI node
> +--------
> +
> +Device trees for SMP systems must have an IPI node representing the mechanism
> +used for inter-processor interrupt generation.
> +
> +Required properties:
> +
> +- compatible: Must be "jcore,ipi-controller".

Again, seems pretty generic.

> +
> +- reg: A memory range used to IPI generation.
> +
> +- interrupts: An irq on which IPI will be received.
> +
> +
> +----------
> +CPUID node
> +----------
> +
> +Device trees for SMP systems must have a CPUID node representing the mechanism
> +used to identify the current processor on which execution is taking place.
> +
> +Required properties:
> +
> +- compatible: Must be "jcore,cpuid-mmio".
> +
> +- reg: A memory range containing a single 32-bit mmio register which produces
> +  the current cpu id when read.

This id matches the reg value in cpu node, right? If not, it should.

Rob