[PATCH v2 1/5] dt-bindings: update device tree binding for Allwinner PRCM CCUs

[icenowy@aosc.xyz (Icenowy Zheng)]

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.

>
> Maxime
>
> --
> Maxime Ripard, Free Electrons
> Embedded Linux and Kernel engineering
> http://free-electrons.com