Re: [PATCH 1/3] clk: versatile add DT bindings for the ICST CM variants

[Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On Wed, Aug 10, 2016 at 11:09:32AM +0200, Linus Walleij wrote:
> The Integrator/AP and Integrator/CP core modules have special
> versions of the ICST525 interface hardcoding some bits. Create
> special compatible strings to identify these variants, also
> explain a bit what is going on.
> 
> Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Cc: Russell King <linux-I+IVW8TIWO2tmTQ+vhA3Yw@public.gmane.org>
> Signed-off-by: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---
>  .../devicetree/bindings/clock/arm-syscon-icst.txt  | 35 ++++++++++++++++++++--
>  1 file changed, 33 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/clock/arm-syscon-icst.txt b/Documentation/devicetree/bindings/clock/arm-syscon-icst.txt
> index 8b7177cecb36..48886490591a 100644
> --- a/Documentation/devicetree/bindings/clock/arm-syscon-icst.txt
> +++ b/Documentation/devicetree/bindings/clock/arm-syscon-icst.txt
> @@ -5,20 +5,51 @@ Technology (IDT). ARM integrated these oscillators deeply into their
>  reference designs by adding special control registers that manage such
>  oscillators to their system controllers.
>  
> -The ARM system controller contains logic to serialize and initialize
> +The ARM system controllers contains logic to serialize and initialize

s/contains/contain/

>  an ICST clock request after a write to the 32 bit register at an offset
>  into the system controller. Furthermore, to even be able to alter one of
>  these frequencies, the system controller must first be unlocked by
>  writing a special token to another offset in the system controller.
>  
> +The ARM Integrator/AP and Integrator/CP core modules and baseboard contain
> +special versions of the serial interface that only connects the low 8 bits
> +of the VDW (missing one bit), hardwires RDW to different values and sometimes
> +als hardwire the output divider. They therefore have special compatible

s/als/also/

I don't see what is special here. Different h/w is supposed to have 
different compatible strings. I'd word this more, so that you don't have 
to change it again if another compatible string is added.

> +strings as per this table (the OD value is the value on the pins, not the
> +resulting output divider):
> +
> +Integrator variant:      RDW     OD          VDW
> +
> +Integrator/AP            22      1           Bit 8 0, rest variable
> +integratorap-cm
> +
> +Integrator/AP            46      3           Bit 8 0, rest variable
> +integratorap-sys
> +
> +Integrator/AP            22 or   1           17 or (33 or 25 MHz)
> +integratorap-pci         14      1           14
> +
> +Integrator/CP            22      variable    Bit 8 0, rest variable
> +integratorcp-cm-core
> +
> +Integrator/CP            22      variable    Bit 8 0, rest variable
> +integratorcp-cm-mem
> +
>  The ICST oscillator must be provided inside a system controller node.
>  
>  Required properties:
> +- compatible: must be one of
> +  "arm,syscon-icst525"
> +  "arm,syscon-icst307"
> +  "arm,syscon-icst525-integratorap-cm"
> +  "arm,syscon-icst525-integratorap-sys"
> +  "arm,syscon-icst525-integratorap-pci"
> +  "arm,syscon-icst525-integratorcp-cm-core"
> +  "arm,syscon-icst525-integratorcp-cm-mem"
>  - lock-offset: the offset address into the system controller where the
>    unlocking register is located
>  - vco-offset: the offset address into the system controller where the
>    ICST control register is located (even 32 bit address)
> -- compatible: must be one of "arm,syscon-icst525" or "arm,syscon-icst307"
>  - #clock-cells: must be <0>
>  - clocks: parent clock, since the ICST needs a parent clock to derive its
>    frequency from, this attribute is compulsory.
> -- 
> 2.7.4
> 
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