linux-kernel - Re: [PATCH v8 04/16] clk: npcm8xx: add clock controller

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Message-Id: <20220804200549.60512C433C1@smtp.kernel.org>
Date:   Thu, 04 Aug 2022 13:05:47 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Tomer Maimon <tmaimon77@...il.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Avi Fishman <avifishman70@...il.com>,
        Benjamin Fair <benjaminfair@...gle.com>,
        Biju Das <biju.das.jz@...renesas.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Greg KH <gregkh@...uxfoundation.org>,
        Jonathan Neuschäfer <j.neuschaefer@....net>,
        Jiri Slaby <jirislaby@...nel.org>,
        Joel Stanley <joel@....id.au>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Lubomir Rintel <lkundrak@...sk>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        Michael Turquette <mturquette@...libre.com>,
        Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@...hiba.co.jp>,
        Olof Johansson <olof@...om.net>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Robert Hancock <robert.hancock@...ian.com>,
        Rob Herring <robh+dt@...nel.org>,
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        Nancy Yuen <yuenn@...gle.com>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
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        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v8 04/16] clk: npcm8xx: add clock controller

Quoting Tomer Maimon (2022-08-04 07:01:30)
> On Sat, 30 Jul 2022 at 01:56, Stephen Boyd <sboyd@...nel.org> wrote:
> >
> > Because it is jumbled in some range?
> Yes.
> >
> > >
> > > I do see a way to combine the clock and the reset driver, the NPCM
> > > reset driver is serving other NPCM BMC's.
> > > Should we use regmap to handle the clock registers instead of ioremap?
> >
> > Sure? Using regmap or not looks like a parallel discussion. How does it
> > help use platform APIs?
> I mean to use regmap API instead of platform API for handing the clock
> and reset registers.
> the regmap API gives only one user access to R/W (lock).
> I will be happy to get more suggestions, on how should we solve this situation.
> 

Using platform APIs means using platform_*() functions, not of_*()
functions, which are open-firmware/DT related. Regmap can be used to
operate on registers mapped as __iomem, which is different from platform
APIs.

Is having a lock even necessary? Do the reset and clk controls live
within a shared register where we would need to prevent one driver from
accessing that register at the same time as the other?