From: Maxime Ripard <maxime.ripard@free-electrons.com>
To: Icenowy Zheng <icenowy@aosc.xyz>
Cc: Rob Herring <robh+dt@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-sunxi@googlegroups.com" <linux-sunxi@googlegroups.com>
Subject: Re: [PATCH v2 1/5] dt-bindings: update device tree binding for Allwinner PRCM CCUs
Date: Sun, 26 Mar 2017 15:10:37 +0200 [thread overview]
Message-ID: <20170326131037.qkimsobykxxqgxee@lukather> (raw)
In-Reply-To: <997781490224623@web30o.yandex.ru>
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On Thu, Mar 23, 2017 at 07:17:03AM +0800, Icenowy Zheng wrote:
>
>
> 23.03.2017, 04:09, "Maxime Ripard" <maxime.ripard@free-electrons.com>:
> > On Wed, Mar 22, 2017 at 02:22:22AM +0800, Icenowy Zheng wrote:
> >> 21.03.2017, 15:41, "Maxime Ripard" <maxime.ripard@free-electrons.com>:
> >> > On Thu, Mar 16, 2017 at 01:28:04AM +0800, Icenowy Zheng wrote:
> >> >> Many Allwinner SoCs after A31 have a CCU in PRCM block.
> >> >>
> >> >> Give the ones on H3 and A64 compatible strings.
> >> >>
> >> >> Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
> >> >> ---
> >> >> Changes in v2:
> >> >> - Add iosc for R_CCU's on H3/A64. (A31, A23 and A33 seem to have different
> >> >> clock for mux 3 of ar100 clk. Investgations are needed for them.)
> >> >>
> >> >> Documentation/devicetree/bindings/clock/sunxi-ccu.txt | 18 +++++++++++++++++-
> >> >> 1 file changed, 17 insertions(+), 1 deletion(-)
> >> >>
> >> >> diff --git a/Documentation/devicetree/bindings/clock/sunxi-ccu.txt b/Documentation/devicetree/bindings/clock/sunxi-ccu.txt
> >> >> index 68512aa398a9..4a4addff595d 100644
> >> >> --- a/Documentation/devicetree/bindings/clock/sunxi-ccu.txt
> >> >> +++ b/Documentation/devicetree/bindings/clock/sunxi-ccu.txt
> >> >> @@ -7,9 +7,11 @@ Required properties :
> >> >> - "allwinner,sun8i-a23-ccu"
> >> >> - "allwinner,sun8i-a33-ccu"
> >> >> - "allwinner,sun8i-h3-ccu"
> >> >> + - "allwinner,sun8i-h3-r-ccu"
> >> >> - "allwinner,sun8i-v3s-ccu"
> >> >> - "allwinner,sun9i-a80-ccu"
> >> >> - "allwinner,sun50i-a64-ccu"
> >> >> + - "allwinner,sun50i-a64-r-ccu"
> >> >> - "allwinner,sun50i-h5-ccu"
> >> >>
> >> >> - reg: Must contain the registers base address and length
> >> >> @@ -20,7 +22,11 @@ Required properties :
> >> >> - #clock-cells : must contain 1
> >> >> - #reset-cells : must contain 1
> >> >>
> >> >> -Example:
> >> >> +For the PRCM CCUs on H3/A64, one more clock is needed:
> >> >> +- "iosc": another frequency oscillator used for CPUS (usually at 32000Hz,
> >> >> + not the same with losc)
> >> >
> >> > This is called the internal oscillator in the datasheet, it would
> >> > probably make more sense to call it that way in the documentation too.
> >> >
> >> > This oscillator seems to be clocked at 16MHz, so we should represent
> >> > it as such.
> >> >
> >> > And I'm wondering, are you *sure* that it's fed directly from the
> >> > internal oscillator, or goes through the registers in the RTC, with
> >> > the 32 divider and 16 prescaler by default that makes it at roughly
> >> > the same rate (31.25kHz).
> >>
> >> In fact I know nothing about it -- I only represented the code in BSP
> >> clock driver.
> >>
> >> The mux value 3 varies from SoC to SoC. For A64/H5 it's 32000,
> >> for A33 it's 667000 (seems to be directly the internal OSC, as the
> >> user manual says the internal OSC is 600~700kHz; but it's named
> >> cpuosc rather than iosc in A33 BSP clock driver); for A80 it's even
> >> PLL_AUDIO.
> >
> > Where are you getting those info from?
> >
> > As far as I know, the A33 PRCM takes the hosc, losc, pll6 and CPU
> > (internal) oscillator:
> > https://github.com/allwinner-zh/linux-3.4-sunxi/blob/master/drivers/clk/sunxi/clk-sun8iw5.c#L508
> >
> > The H3 takes the hosc and losc:
> > https://github.com/allwinner-zh/linux-3.4-sunxi/blob/master/drivers/clk/sunxi/clk-sun8iw7.c#L379
> >
> > The A80 takes the hosc and losc:
> > https://github.com/allwinner-zh/linux-3.4-sunxi/blob/master/drivers/clk/sunxi/clk-sun9iw1.c#L281
> >
> > The A64 takes the hosc, losc, pll-periph0 and the iosc, which indeed
> > seems to be fed from the internal oscillator with the divider in the
> > RTC:
> > https://github.com/longsleep/linux-pine64/blob/lichee-dev-v3.10.65-bsp2.0/arch/arm64/boot/dts/sun50iw1p1-clk.dtsi#L19
> > https://github.com/longsleep/linux-pine64/blob/lichee-dev-v3.10.65-bsp2.0/drivers/clk/sunxi/clk-sun50iw1.c#L603
>
> But then in sunxi_init_clocks function, the iosc clock is initialized
> as a fixed clock with 32000Hz.
>
> The clock node in BSP device tree have a compatible of
> allwinner,fixed-clock, but not fixed-clock, which makes it not able
> to be really probed.
That clock is registered:
https://github.com/longsleep/linux-pine64/blob/lichee-dev-v3.10.65-bsp2.0/drivers/clk/sunxi/clk-sun50iw1.c#L1193
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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next prev parent reply other threads:[~2017-03-27 8:54 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20170315172808.64011-1-icenowy@aosc.xyz>
[not found] ` <20170315172808.64011-2-icenowy@aosc.xyz>
2017-03-21 7:41 ` [PATCH v2 1/5] dt-bindings: update device tree binding for Allwinner PRCM CCUs Maxime Ripard
[not found] ` <115431490120542@web34g.yandex.ru>
2017-03-22 20:09 ` Maxime Ripard
[not found] ` <997781490224623@web30o.yandex.ru>
2017-03-26 13:10 ` Maxime Ripard [this message]
[not found] <20170327091147.6B24A7C19A5@relay.mailchannels.net>
2017-03-27 13:47 ` Maxime Ripard
2017-03-27 19:13 ` icenowy
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