Messages in this thread | | | Date | Sun, 14 Oct 2012 13:13:54 +0200 | From | Daniel Mack <> | Subject | Re: [RFC] Common clock framework for external clock generators |
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Hi,
On 14.10.2012 12:59, Sebastian Hesselbarth wrote: > Adding LAKML and devtree as there might be people willing to comment about > DT representation of i2c-attached clock generators, too. > > On 10/12/2012 08:17 PM, Daniel Mack wrote: >> On 11.10.2012 18:00, Sebastian Hesselbarth wrote: > >> [...] >>> Does any of you work rely on a working si5351 driver? >> >> Yes, it does actually. I can hack around it for now, but at some point, >> a proper driver is needed. And yours looks quite feature complete, so it >> would be easiest to finish this one :) > > Well, yes it is some kind of feature complete except regmap and DT. Adding > regmap to the driver should be quite easy but with DT I am still thinking > of the best way to represent the internal connections between OSC, PLLs, and > CLKOUTs. In the last version of the driver I had a callback that was > board specific to setup these connections but with DT there will be no board > specific code anymore. > > Maybe one of the common clk maintainers can give a hint how this could be > done in a clean way. The question is how to represent a i2c-attached clock > generator config in DT where you want to setup clock parents of CLKOUTs and > PLLs. > > A possible solution would be something like this: > > si5351a@60 { > compatible = "silabs,si5351a"; > reg = <0x60>; > > si_osc: osc { > compatible = "fixed-clock"; > clock-frequency = <270000000>; > }; > > si_plla: pll@0 { > compatible = "silabs,si5351-pll"; > /* hook-up plla to osc input */ > clocks = <&si_osc>; > }; > > si_clkout0: clkout@0 { > compatible = "silabs,si5351-clkout"; > /* hook-up clkout0 to plla */ > clocks = <&si_plla>; > /* request target frequency */ > clock-frequency = <148500000>; > }; > }; > > Although this perfectly describes the clock hierarchy I still don't like > the sub-node style. Another flat solution would be something like:
I think the sub-node style above it nicer because it allows referencing the individual clocks outputs with a phandle. We use this chip to generate base-frequencies for audio clocks, and so we have to switch between two freqs for the multiples of 22.5KHz and 24KHz at runtime.
>> Do you still have access to hardware you wrote the driver for? Let me >> know if you need any help around here. > > Yes, hardware is still available although I only have access to the Si5351a > with 3 clkouts. The code should be compatible for Si5351a with 8 clkouts and > code skeleton for 5351b (OSC and VXCO input) and 5351c (OSC and CLKIN) is > there but untested.
The 3 clkout model is the only one I have access to as well.
> I've transferred the current driver version to my repository to work on. As soon > as I have regmap done, I will push it online and give you a note.
That's great. Let me know if you want me to test anything.
Thanks, Daniel
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