[PATCH 1/3] Documentation: dt: Add TI SCI clock driver

[Tero Kristo]

On 30/10/16 22:41, Rob Herring wrote:
> On Fri, Oct 21, 2016 at 03:45:59PM +0300, Tero Kristo wrote:
>> Add a clock implementation, TI SCI clock, that will hook to the common
>> clock framework, and allow each clock to be controlled via TI SCI
>> protocol.
>>
>> Signed-off-by: Tero Kristo <t-kristo at ti.com>
>> ---
>>  .../devicetree/bindings/clock/ti,sci-clk.txt       | 37 ++++++++++++++++++++++
>>  MAINTAINERS                                        |  1 +
>>  2 files changed, 38 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/clock/ti,sci-clk.txt
>>
>> diff --git a/Documentation/devicetree/bindings/clock/ti,sci-clk.txt b/Documentation/devicetree/bindings/clock/ti,sci-clk.txt
>> new file mode 100644
>> index 0000000..bfc3ca4
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/clock/ti,sci-clk.txt
>> @@ -0,0 +1,37 @@
>> +Texas Instruments TI-SCI Clocks
>> +===============================
>> +
>> +All clocks on Texas Instruments' SoCs that contain a System Controller,
>> +are only controlled by this entity. Communication between a host processor
>> +running an OS and the System Controller happens through a protocol known
>> +as TI-SCI[1]. This clock implementation plugs into the common clock
>> +framework and makes use of the TI-SCI protocol on clock API requests.
>> +
>> +[1] Documentation/devicetree/bindings/arm/keystone/ti,sci.txt
>> +
>> +Required properties:
>> +-------------------
>> +- compatible: Must be "ti,k2g-sci-clk"
>> +- #clock-cells: Shall be 2.
>> +  In clock consumers, this cell represents the device ID and clock ID
>> +  exposed by the PM firmware. The assignments can be found in the header
>> +  files <dt-bindings/genpd/<soc>.h> (which covers the device IDs) and
>> +  <dt-bindings/clock/<soc>.h> (which covers the clock IDs), where <soc>
>> +  is the SoC involved, for example 'k2g'.
>> +
>> +Examples:
>> +--------
>> +
>> +pmmc: pmmc {
>> +	compatible = "ti,k2g-sci";
>> +
>> +	k2g_clks: k2g_clks {
>
> Use "clocks" for node name instead.
>
>> +		compatible = "ti,k2g-sci-clk";
>
> I'm starting to think all these child nodes for SCI are pointless. Is
> there any reason why the parent node can't be the clock provider (along
> with all the other providers it acks as)?

I believe the only reason to keep them separate is to have kernel side 
of things modular. If we have separate nodes, the drivers can be probed 
separately.

If not, we need to build one huge blob with all the features in it, so 
the main driver can probe everything in one go, with annoying 
back-and-forth callbacks in place (assuming we still want to keep stuff 
somehow modular.)

-Tero

>
>> +		#clock-cells = <2>;
>> +	};
>> +};
>> +
>> +uart0: serial at 2530c00 {
>> +	compatible = "ns16550a";
>> +	clocks = <&k2g_clks K2G_DEV_UART0 0>;
>> +};