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

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Message-ID: <CAL_Jsq+DQnfX29AOJWMtH9ZB7=neOVwiyZggEuwOmazzVQ6MVg@mail.gmail.com>
Date:   Fri, 5 Jan 2018 17:27:56 -0600
From:   Rob Herring <robh@...nel.org>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Mark Rutland <mark.rutland@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <marc.zyngier@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Lee Jones <lee.jones@...aro.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 5/6] clocksource: Add a new timer-ingenic driver

On Wed, Jan 3, 2018 at 3:56 PM, Paul Cercueil <paul@...pouillou.net> wrote:
> Hi,
>
> Le mer. 3 janv. 2018 à 22:08, Rob Herring <robh@...nel.org> 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@...pouillou.net>
>>>  ---
>>>   .../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.

Aren't the PWMs connected to something? Describe those in DT and then
you can find the free ones.

Rob