From: Paul Walmsley <paul.walmsley@sifive.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: mark.rutland@arm.com, linux-pwm@vger.kernel.org,
devicetree@vger.kernel.org, Palmer Dabbelt <palmer@sifive.com>,
linux-kernel@vger.kernel.org, robh+dt@kernel.org,
Sachin Ghadi <sachin.ghadi@sifive.com>,
Yash Shah <yash.shah@sifive.com>,
Thierry Reding <thierry.reding@gmail.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
linux-riscv@lists.infradead.org
Subject: Re: [PATCH 2/2] pwm: sifive: Add a driver for SiFive SoC PWM
Date: Wed, 16 Jan 2019 09:18:45 -0800 (PST) [thread overview]
Message-ID: <alpine.DEB.2.21.9999.1901160909540.19681@viisi.sifive.com> (raw)
In-Reply-To: <20190116164640.mi3zjbhbhc6k5v7p@pengutronix.de>
[-- Attachment #1: Type: text/plain, Size: 2256 bytes --]
On Wed, 16 Jan 2019, Uwe Kleine-König wrote:
> On Wed, Jan 16, 2019 at 04:40:42PM +0530, Yash Shah wrote:
> > On Wed, Jan 16, 2019 at 3:30 AM Uwe Kleine-König
> > <u.kleine-koenig@pengutronix.de> wrote:
> > > On Fri, Jan 11, 2019 at 01:52:44PM +0530, Yash Shah wrote:
> > > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> > > > index a8f47df..3bcaf6a 100644
> > > > --- a/drivers/pwm/Kconfig
> > > > +++ b/drivers/pwm/Kconfig
> > > > @@ -380,6 +380,16 @@ config PWM_SAMSUNG
> > > > To compile this driver as a module, choose M here: the module
> > > > will be called pwm-samsung.
> > > >
> > > > +config PWM_SIFIVE
> > > > + tristate "SiFive PWM support"
> > > > + depends on OF
> > > > + depends on COMMON_CLK
> > >
> > > I'd say add:
> > >
> > > depends on MACH_SIFIVE || COMPILE_TEST
> > >
> > > (I guess "MACH_SIFIVE" is wrong, but I assume you get what I mean.)
> >
> > As of now, MACH_SIFIVE/ARCH_SIFIVE isn't available.
> > @Paul, Do you have any comments on this?
>
> If this is not going to be available at least protect it by
>
> depends RISCV || COMPILE_TEST
There's nothing RISC-V or SiFive SoC-specific about this driver or IP
block. The HDL for this IP block is open-source and posted on Github.
The IP block and driver would work unchanged on an ARM or MIPS SoC, and in
fact, SiFive does design ARM-based SoCs as well. Likewise, any other SoC
vendor could take the HDL for this IP block from the git tree and
implement it on their own SoC.
More generally: it's a basic principle of Linux device drivers that they
should be buildable for any architecture. The idea here is to prevent
developers from burying architecture or SoC-specific hacks into the
driver. So there shouldn't be any architecture or SoC-specific code in
any device driver, unless it's abstracted in some way - ideally through a
common framework.
So from this point of view, neither "depends MACH_SIFIVE" nor "depends
RISCV" would be appropriate. Similarly, the equivalents for other
architectures (e.g. "ARCH_ARM") or SoC manufacturers (e.g.,
"MACH_SAMSUNG") wouldn't be appropriate for any generic IP block device
driver like this one.
- Paul
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next prev parent reply other threads:[~2019-01-16 17:18 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-11 8:22 [PATCH 0/2] PWM support for HiFive Unleashed Yash Shah
2019-01-11 8:22 ` [PATCH 1/2] pwm: sifive: Add DT documentation for SiFive PWM Controller Yash Shah
2019-01-15 20:11 ` Uwe Kleine-König
2019-01-16 9:21 ` Yash Shah
2019-01-21 11:20 ` Thierry Reding
2019-01-11 8:22 ` [PATCH 2/2] pwm: sifive: Add a driver for SiFive SoC PWM Yash Shah
2019-01-15 15:27 ` Christoph Hellwig
2019-01-15 22:00 ` Uwe Kleine-König
2019-01-16 11:10 ` Yash Shah
2019-01-16 16:46 ` Uwe Kleine-König
2019-01-16 17:18 ` Paul Walmsley [this message]
2019-01-16 17:28 ` Uwe Kleine-König
2019-01-16 19:29 ` Paul Walmsley
2019-01-17 8:19 ` Uwe Kleine-König
2019-01-21 11:54 ` Thierry Reding
2019-01-21 15:11 ` Uwe Kleine-König
2019-01-17 6:45 ` Yash Shah
2019-01-17 7:28 ` Uwe Kleine-König
2019-01-21 11:30 ` Thierry Reding
2019-01-21 13:23 ` Uwe Kleine-König
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