Re: [PATCH v2 5/6] clocksource: Add a new timer-ingenic driver

[Paul Cercueil]

Hi,

Le mer. 3 janv. 2018 à 22:08, Rob Herring <robh@xxxxxxxxxx> a écrit :
> On Mon, Jan 01, 2018 at 03:33:43PM +0100, Paul Cercueil wrote:
> >  This driver will use the TCU (Timer Counter Unit) present on the 
> > Ingenic
> >  JZ47xx SoCs to provide the kernel with a clocksource and timers.
> >
> >  Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >  ---
> >   .../devicetree/bindings/timer/ingenic,tcu.txt      |  35 +++
>
> Separate patch please.

OK.

> >   drivers/clocksource/Kconfig                        |   8 +
> >   drivers/clocksource/Makefile                       |   1 +
> >   drivers/clocksource/timer-ingenic.c                | 256 
> > +++++++++++++++++++++
> >   4 files changed, 300 insertions(+)
> >   create mode 100644 
> > Documentation/devicetree/bindings/timer/ingenic,tcu.txt
> >   create mode 100644 drivers/clocksource/timer-ingenic.c
> >
> >   v2: Use SPDX identifier for the license
> >
> >  diff --git 
> > a/Documentation/devicetree/bindings/timer/ingenic,tcu.txt 
> > b/Documentation/devicetree/bindings/timer/ingenic,tcu.txt
> >  new file mode 100644
> >  index 000000000000..e4944972ea53
> >  --- /dev/null
> >  +++ b/Documentation/devicetree/bindings/timer/ingenic,tcu.txt
> >  @@ -0,0 +1,35 @@
> >  +Ingenic JZ47xx SoCs Timer/Counter Unit driver
> >  +---------------------------------------------
> >  +
> >  +Required properties:
> >  +
> >  +- compatible : should be "ingenic,<socname>-tcu". Valid strings 
> > are:
> >  +  * ingenic,jz4740-tcu
> >  +  * ingenic,jz4770-tcu
> >  +  * ingenic,jz4780-tcu
> >  +- interrupt-parent : phandle of the TCU interrupt controller.
> >  +- interrupts : Specifies the interrupts the controller is 
> > connected to.
> >  +- clocks : List of phandle & clock specifiers for the TCU clocks.
> >  +- clock-names : List of name strings for the TCU clocks.
> >  +- ingenic,channels: a list of TCU channels to be used as timers.
>
> Why is this needed? This looks like you are trying to assign certain
> timers to clocksource and clockevent. A common problem, but one that
> should be decided by describing h/w features. There must be some
> property present or missing to make you decide to use a given channel 
> or
> not.

Well, it's not easy; some TCU channels will be used as PWM, and there's 
no way
to know that when the clocksource driver probes. And which ones are PWM 
/ which
ones are not, is board-specific. If you have a better solution though, 
I take it.

> >  +
> >  +Example:
> >  +
> >  +/ {
> >  +	regmap {
> >  +		compatible = "simple-mfd", "syscon";
> >  +		reg = <0x10002000 0x1000>;
> >  +
> >  +		tcu: timer {
> >  +			compatible = "ingenic,jz4740-tcu";
> >  +
> >  +			clocks = <&tcu 0>, <&tcu 1>;
> >  +			clock-names = "timer0", "timer1";
>
> It's curious that you have timer0 and timer1 here and then channels 0
> and 1 below. Would your clocks change if you use channel 2 for 
> example?
> The binding should be a list of clock connections in the h/w, not
> just what the driver needs or what the used h/w configuration is.
>
> Rob

I only put these to simplify the example, but you're right, I should 
have
all the timer clocks supplied there.

Thanks,
-Paul