linux-kernel - Re: [PATCH 2/3] clk: renesas: r8a7795: Add ccree clock

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Message-ID: <CAMuHMdWxfZO+a0+tcd+4juNTVwB_nnJi0_SFD2C3OLCF1nSbKw@mail.gmail.com>
Date:   Thu, 17 May 2018 10:41:46 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Gilad Ben-Yossef <gilad@...yossef.com>
Cc:     Simon Horman <horms@...ge.net.au>,
        Magnus Damm <magnus.damm@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Ofir Drang <ofir.drang@....com>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>
Subject: Re: [PATCH 2/3] clk: renesas: r8a7795: Add ccree clock

Hi Gilad,

On Thu, May 17, 2018 at 10:00 AM, Gilad Ben-Yossef <gilad@...yossef.com> wrote:
> On Tue, May 15, 2018 at 5:47 PM, Geert Uytterhoeven
> <geert@...ux-m68k.org> wrote:
>> On Tue, May 15, 2018 at 2:29 PM, Gilad Ben-Yossef <gilad@...yossef.com> wrote:
>>> This patch adds the clock used by the CryptoCell 630p instance in the SoC.
>>>
>>> Signed-off-by: Gilad Ben-Yossef <gilad@...yossef.com>
>>
>> Thanks for your patch!
>>
>>> --- a/drivers/clk/renesas/r8a7795-cpg-mssr.c
>>> +++ b/drivers/clk/renesas/r8a7795-cpg-mssr.c
>>> @@ -132,6 +132,7 @@ static struct mssr_mod_clk r8a7795_mod_clks[] __initdata = {
>>>         DEF_MOD("sys-dmac2",             217,   R8A7795_CLK_S0D3),
>>>         DEF_MOD("sys-dmac1",             218,   R8A7795_CLK_S0D3),
>>>         DEF_MOD("sys-dmac0",             219,   R8A7795_CLK_S0D3),
>>> +       DEF_MOD("ccree",                 229,   R8A7795_CLK_S3D2),
>>
>> I don't know if "ccree" is the proper name for this clock, as there
>> may be multiple
>> instances.
>
> I'd be happy to rename it to anything else. Suggestions?

I believe it should be called "sceg-pub".

>> I also can't verify the parent clock.
>
> I'm afraid I can't really help. This is based on code snippet from
> Renesas. I verified it works but
> I am not an expert on the clock settings :-(

As your driver doesn't care about the clock rate, only about
enabling/disabling the clock, the actual parent doesn't matter much.

After some deeper diving into the datasheet, I believe the correct parent is
the CR clock, which is unfortunately not yet supported by the R-Car H3 clock
driver. I'll send a patch...

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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