Re: [PATCH 03/14] DEVICETREE: Add PIC32 clock binding documentation

[Rob Herring <robh@kernel.org>]

On Fri, Nov 20, 2015 at 05:17:15PM -0700, Joshua Henderson wrote:
> From: Purna Chandra Mandal <purna.mandal@microchip.com>
> 
> Document the devicetree bindings for the clock driver found on Microchip
> PIC32 class devices.
> 
> Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
> Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
> ---
>  .../devicetree/bindings/clock/microchip,pic32.txt  |  263 ++++++++++++++++++++
>  1 file changed, 263 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/microchip,pic32.txt
> 
> diff --git a/Documentation/devicetree/bindings/clock/microchip,pic32.txt b/Documentation/devicetree/bindings/clock/microchip,pic32.txt
> new file mode 100644
> index 0000000..4cef72d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/microchip,pic32.txt
> @@ -0,0 +1,263 @@
> +Binding for a Clock hardware block found on
> +certain Microchip PIC32 MCU devices.
> +
> +Microchip SoC clocks-node consists of few oscillators, PLL, multiplexer
> +and few divider nodes.

[...]

> +Required properties:
> +- compatible : should have "microchip,pic32-clk".
> +- reg : A Base address and length of the register set.
> +- interrupts : source of interrupt.
> +
> +Optional properties (for subnodes):
> +- #clock-cells: From common clock binding, should be 0.
> +
> +- microchip,clock-indices: in multiplexer node clock sources always aren't linear
> +    and contiguous. This property helps define clock-sources with respect to
> +    the mux clock node.
> +
> +- microchip,ignore-unused : ignore gate request even if the gated clock is unused.

There is some discussion about this upstream with "critical-clocks" 
binding. Can you use and wait for that?

> +- microchip,status-bit-mask: bitmask for status check. This will be used to confirm
> +    particular operation by clock sub-node is completed. It is dependent sub-node.
> +- microchip,bit-mask: enable mask, similar to microchip,status-bit-mask.

We've generally decided not to describe clocks at this level of detail 
in DT. It's fine though for simple clock trees. This one seems to be 
borderline IMO.

> +- microchip,slew-step: enable frequency slewing(stepping) during rate change;
> +    applicable only to sys-clock subnode.