linux-kernel - Re: [PATCH 2/3] nvmem: Add spmi-nvmem driver

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Message-ID: <20250417143053.GD8400@robin.jannau.net>
Date: Thu, 17 Apr 2025 16:30:53 +0200
From: Janne Grunau <j@...nau.net>
To: Srinivas Kandagatla <srini@...nel.org>
Cc: fnkl.kernel@...il.com, Sven Peter <sven@...npeter.dev>,
	Alyssa Rosenzweig <alyssa@...enzweig.io>,
	Neal Gompa <neal@...pa.dev>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, asahi@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, Hector Martin <marcan@...can.st>
Subject: Re: [PATCH 2/3] nvmem: Add spmi-nvmem driver

On Thu, Apr 17, 2025 at 02:34:37PM +0100, Srinivas Kandagatla wrote:
> 
> 
> On 15/04/2025 22:52, Sasha Finkelstein via B4 Relay wrote:
> > From: Hector Martin <marcan@...can.st>
> > 
> > This driver exposes a SPMI device as an NVMEM device.
> > It is intended to be used with e.g. PMUs/PMICs that are used to
> > hold power management configuration, such as used on Apple Silicon
> > Macs.
> > 
> > Signed-off-by: Hector Martin <marcan@...can.st>
> > Signed-off-by: Sasha Finkelstein <fnkl.kernel@...il.com>
> > ---
> >   MAINTAINERS                |  1 +
> >   drivers/nvmem/Kconfig      | 14 +++++++++++
> >   drivers/nvmem/Makefile     |  2 ++
> >   drivers/nvmem/spmi-nvmem.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++
> >   4 files changed, 79 insertions(+)
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index e7b2d0df81b387ba5398957131971588dc7b89dc..63c12f901aed1f3e6de8227d6db34af1bd046fe6 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -2298,6 +2298,7 @@ F:	drivers/iommu/io-pgtable-dart.c
> >   F:	drivers/irqchip/irq-apple-aic.c
> >   F:	drivers/nvme/host/apple.c
> >   F:	drivers/nvmem/apple-efuses.c
> > +F:	drivers/nvmem/spmi-nvmem.c
> >   F:	drivers/pinctrl/pinctrl-apple-gpio.c
> >   F:	drivers/pwm/pwm-apple.c
> >   F:	drivers/soc/apple/*
> > diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> > index 8671b7c974b933e147154bb40b5d41b5730518d2..9ec907d8aa6ef7df0ea45cc35e92d8239d2705ee 100644
> > --- a/drivers/nvmem/Kconfig
> > +++ b/drivers/nvmem/Kconfig
> > @@ -310,6 +310,20 @@ config NVMEM_SNVS_LPGPR
> >   	  This driver can also be built as a module. If so, the module
> >   	  will be called nvmem-snvs-lpgpr.
> >   
> > +config NVMEM_SPMI
> > +	tristate "Generic SPMI NVMEM"
> > +	default ARCH_APPLE
> Why default is set to ARCH_APPLE?
> 
> This will endup with y in arm64 defconfig, means increasing the size of 
> kernel.
> 
> should it be:
> 
> depends on ARCH_APPLE || COMPILE_TEST

I don't think it should depend on ARCH_APPLE. There is nothing
ARCH_APPLE specific in the driver or dt-bindings even apple platforms
are currently only user.

`default m if ARCH_APPLE` might an alternative but in this specific case
the driver which will uses the nvmem cells should just select it. So I
would remove the default.

Janne