linux-kernel - Re: [PATCH v2 3/7] arm64/sysreg: Convert SPE registers to automatic generation

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Message-ID: <Y1FcRNhFpZxZ7AMx@sirena.org.uk>
Date:   Thu, 20 Oct 2022 15:33:40 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Namhyung Kim <namhyung@...nel.org>,
        James Morse <james.morse@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Marc Zyngier <maz@...nel.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Will Deacon <will@...nel.org>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Jiri Olsa <jolsa@...nel.org>, kvmarm@...ts.cs.columbia.edu,
        kvmarm@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/7] arm64/sysreg: Convert SPE registers to automatic
 generation

On Wed, Oct 19, 2022 at 02:11:26PM -0500, Rob Herring wrote:
> Convert all the SPE register defines to automatic generation. No
> functional changes.
> 
> New registers and fields for SPEv1.2 are added with the conversion.
> 
> Some of the PMBSR MSS field defines are kept as the automatic generation
> has no way to create multiple names for the same register bits. The
> meaning of the MSS field depends on other bits.

A few small things below from checking against DDI0487I.a, nothing
major:

> +Sysreg	PMSCR_EL1	3	0	9	9	0
> +Res0	63:8
> +Field	7:6	PCT

Given the potential multiple meanings depending on both integration and
runtime configuration representing this as a field seems sensible.

> +Sysreg	PMSNEVFR_EL1	3	0	9	9	1
> +Field	63:0	E
> +EndSysreg

While this does look rather different to the spec it does appear to be a
sensible interpretation - the intent is clearly to have a mask of
feature bits.

> +Sysreg	PMSIDR_EL1	3	0	9	9	7

> +Field	23:20	FORMAT
> +Field	19:16	COUNTSIZE
> +Field	15:12	MAXSIZE
> +Field	11:8	INTERVAL

These should really be enums.

> +Sysreg	PMBLIMITR_EL1	3	0	9	10	0
> +Enum	2:1	FM
> +	0b0000	STOP_IRQ
> +EndEnum

DDI0487I.a also defines

	0b01	DISCARD

from FEAT_SPEv1p2.  Also this is a two bit field so 0b00 would be a bit
better.

> +Sysreg	PMBSR_EL1	3	0	9	10	3
> +Res0	63:32
> +Enum	31:26	EC
> +	0b000000	BUF
> +	0b100100	FAULT_S1
> +	0b100101	FAULT_S2
> +EndEnum

DDI0487I.a also has

	0b011110	FAULT_GPC
	0b011111	IMP_DEF

(the former from FEAT_RME).

> +Sysreg	PMBIDR_EL1	3	0	9	10	7
> +Res0	63:12
> +Field	11:8	EA

This looks like it should be described as an enum.

> +Field	3:0	ALIGN

This could potentially also be an enum.

> +Sysreg	PMSCR_EL2	3	4	9	9	0
> +Res0	63:8
> +Field	7:6	PCT

This lookslike it should be an enum.

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