Device tree node for Freescale Gianfar PTP reference clock source selection

Device tree node for Freescale Gianfar PTP reference clock source selection

[Aida Mynzhasova]

Hi,

Currently, Freescale Gianfar PTP reference clock source is determined 
through hard-coded value in gianfar_ptp driver. I don't think that 
recompilation of the entire module (or even worse - the kernel) is a god 
idea when we want to change one clock source to another. So, I want to 
add new device tree binding, which can be used as:

	ptp_clock@24E00 {
		compatible = "fsl,etsec-ptp";
		reg = <0x24E00 0xB0>;
		interrupts = <12 0x8 13 0x8>;
		interrupt-parent = < &ipic >;
		fsl,cksel = <0>; /* <-- New entry */
		fsl,tclk-period = <10>;
		fsl,tmr-prsc    = <100>;
		fsl,tmr-add     = <0x999999A4>;
		fsl,tmr-fiper1  = <0x3B9AC9F6>;
		fsl,tmr-fiper2  = <0x00018696>;
		fsl,max-adj     = <659999998>;
	};

fsl,cksel acceptable values:

<0> for external clock;
<1> for eTSEC system clock;
<2> for eTSEC1 transmit clock;
<3> for RTC clock input.

I am new in this mailing list, and as far as I know, I have to discuss 
all updates for device tree files here before sending patch, which uses 
new attributes.

Also, should I define new bindings in some special way? I want to add 
description of cksel attribute in 
/Documentation/devicetree/bindings/net/fsl-tsec-phy.txt. Is it enough or 
not?

Thanks!

-- 
Regards,
Aida

Re: Device tree node for Freescale Gianfar PTP reference clock source selection

[Scott Wood]

On Mon, 2013-09-23 at 11:37 +0400, Aida Mynzhasova wrote:
> Hi,
> 
> Currently, Freescale Gianfar PTP reference clock source is determined 
> through hard-coded value in gianfar_ptp driver. I don't think that 
> recompilation of the entire module (or even worse - the kernel) is a god 
> idea when we want to change one clock source to another. So, I want to 
> add new device tree binding, which can be used as:

Is this describing the hardware or how you're using it?  If the latter,
it should be a module parameter or some sort of runtime knob instead.

> 	ptp_clock@24E00 {
> 		compatible = "fsl,etsec-ptp";
> 		reg = <0x24E00 0xB0>;
> 		interrupts = <12 0x8 13 0x8>;
> 		interrupt-parent = < &ipic >;
> 		fsl,cksel = <0>; /* <-- New entry */
> 		fsl,tclk-period = <10>;
> 		fsl,tmr-prsc    = <100>;
> 		fsl,tmr-add     = <0x999999A4>;
> 		fsl,tmr-fiper1  = <0x3B9AC9F6>;
> 		fsl,tmr-fiper2  = <0x00018696>;
> 		fsl,max-adj     = <659999998>;
> 	};
> 
> fsl,cksel acceptable values:
> 
> <0> for external clock;
> <1> for eTSEC system clock;
> <2> for eTSEC1 transmit clock;
> <3> for RTC clock input.
> 
> I am new in this mailing list, and as far as I know, I have to discuss 
> all updates for device tree files here before sending patch, which uses 
> new attributes.
> 
> Also, should I define new bindings in some special way? I want to add 
> description of cksel attribute in 
> /Documentation/devicetree/bindings/net/fsl-tsec-phy.txt. Is it enough or 
> not?

Assuming this is actually describing how the hardware is wired up, yes,
that's how you'd document it (making sure that device trees without that
property are interpreted the same as today).

-Scott