Re: [PATCH v3 28/38] rtc: add HAS_IOPORT dependencies

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "Niklas Schnelle" <schnelle@linux.ibm.com>,
	"Alexandre Belloni" <alexandre.belloni@bootlin.com>,
	"Alessandro Zummo" <a.zummo@towertech.it>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"Alan Stern" <stern@rowland.harvard.edu>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	"Paul Walmsley" <paul.walmsley@sifive.com>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	linux-kernel@vger.kernel.org,
	Linux-Arch <linux-arch@vger.kernel.org>,
	linux-pci@vger.kernel.org, "Arnd Bergmann" <arnd@kernel.org>,
	linux-rtc@vger.kernel.org,
	linux-m68k <linux-m68k@lists.linux-m68k.org>
Subject: Re: [PATCH v3 28/38] rtc: add HAS_IOPORT dependencies
Date: Tue, 9 May 2023 10:51:05 +0200	[thread overview]
Message-ID: <CAMuHMdV-CY_foGPY5PZV=W92rnvSa0X3PTsUoBpzQ6vCNLSzEw@mail.gmail.com> (raw)
In-Reply-To: <552c51fb-41b2-430b-b13c-0e578098dbf6@app.fastmail.com>

Hi Arnd,

On Tue, May 9, 2023 at 10:23 AM Arnd Bergmann <arnd@arndb.de> wrote:
> On Tue, May 9, 2023, at 08:38, Geert Uytterhoeven wrote:
> > On Mon, May 8, 2023 at 10:01 PM Arnd Bergmann <arnd@arndb.de> wrote:
> >> On Mon, May 8, 2023, at 17:36, Niklas Schnelle wrote:
> >>
> >> I think the m68k/atari and mips/dec variants don't necessarily
> >> qualify as PIO, those are really just pointer dereferences, and
> >> they don't use the actual inb/outb functions.
> >>
> >> On atari, it looks like HAS_IOPORT may be set if ATARI_ROM_ISA
> >> is, but on dec it's never enabled.
> >
> > Atari does not use RTC_DRV_CMOS, but still relies on generic RTC
> > instead.
>
> Ah right, I now remember working on that code, so we're good on
> m68k then. I think it should work for everyone using
>
>        depends on HAS_IOPORT || ARCH_DECSTATION
>
> in that case, as that is the only exception.
>
> > Last time (in 2013?) I tried converting to RTC_DRV_CMOS by registering
> > an "rtc_cmos" platform device, I couldn't get it to work.
>
> If you ever want to revisit this, I suspect the harder part here
> is to detach arch/m68k/ from the RTC_DRV_GENERIC code first, pushing
> the device registration into the individual machine specific time.c
> code. It's probably not even worth trying to share the rtc-cmos
> driver, but it might be useful to share the library code like
> RTC_DRV_ALPHA does.

Arch/m68k is not that entangled with RTC_DRV_GENERIC, as amiga_defconfig
does not enable it, but enables CONFIG_RTC_DRV_MSM6242 and
CONFIG_RTC_DRV_RP5C01 instead.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds