Re: [PATCH v3 2/2] hwmon: (ltq-cputemp) add devicetree bindings documentation

From	Rob Herring <robh@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 2/2] hwmon: (ltq-cputemp) add devicetree bindings documentation
Date	2017-09-13 17:30 +0200
Message-ID	<uphLZ-DH-43@gated-at.bofh.it> (permalink)
References	<ukO5Q-dZ-17@gated-at.bofh.it> <ukO5Q-dZ-15@gated-at.bofh.it> <ukV7k-6hA-13@gated-at.bofh.it> <uoWet-3Az-17@gated-at.bofh.it> <up8yZ-3aB-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Wed, Sep 13, 2017 at 12:36 AM, Florian Eckert <fe@dev.tdt.de> wrote:
> Hello Rob
>
>>> > --- /dev/null
>>> > +++ b/Documentation/devicetree/bindings/hwmon/ltq-cputemp.txt
>>> > @@ -0,0 +1,10 @@
>>> > +Lantiq cpu temperatur sensor
>>
>>
>> s/temperatur/temperature/
>
>
> Will update this in a follow up page based on the old one. So no v4?
>
>>
>>> > +
>>> > +Requires node properties:
>>> > +- compatible value :
>>> > +     "lantiq,cputemp"
>>
>>
>> Kind of non-specific. How is this device even accessed without any other
>> property?
>
>
> It does not need any further properties. If this is set in the device tree
> then the driver is loaded.

DT is not the only way to instantiate drivers.

What I meant is how do you access the hardware? That should be evident
from the binding and it is not.

Looking at the driver, you have some memory mapped system control
registers which get ioremapped in arch/mips/lantiq/xway/sysctrl.c and
accesses thru some platform specific macros. That is not the ideal way
to do things as we use syscon and regmap for such things. But that's
all mostly kernel details not so relevant to the DT binding.

For DT, I'd expect this is a child node of the sysctrl block with a
reg property value of <0x40 4> (along with any other child devices).
You could also not even put this in DT and the system controller can
have it's own driver that instantiates the child device for this
driver.

Rob

Thread

Re: [PATCH v3 2/2] hwmon: (ltq-cputemp) add devicetree bindings  documentation Rob Herring <robh@kernel.org> - 2017-09-12 18:30 +0200
  Re: [PATCH v3 2/2] hwmon: (ltq-cputemp) add devicetree bindings  documentation Florian Eckert <fe@dev.tdt.de> - 2017-09-13 07:40 +0200
    Re: [PATCH v3 2/2] hwmon: (ltq-cputemp) add devicetree bindings  documentation Guenter Roeck <linux@roeck-us.net> - 2017-09-13 16:20 +0200
      Re: [PATCH v3 2/2] hwmon: (ltq-cputemp) add devicetree bindings  documentation Florian Eckert <fe@dev.tdt.de> - 2017-09-13 16:50 +0200
        Re: [PATCH v3 2/2] hwmon: (ltq-cputemp) add devicetree bindings  documentation Guenter Roeck <linux@roeck-us.net> - 2017-09-13 17:20 +0200
    Re: [PATCH v3 2/2] hwmon: (ltq-cputemp) add devicetree bindings documentation Rob Herring <robh@kernel.org> - 2017-09-13 17:30 +0200
      Re: [PATCH v3 2/2] hwmon: (ltq-cputemp) add devicetree bindings  documentation Florian Eckert <fe@dev.tdt.de> - 2017-09-14 09:10 +0200
        Re: [PATCH v3 2/2] hwmon: (ltq-cputemp) add devicetree bindings documentation Rob Herring <robh@kernel.org> - 2017-09-20 05:00 +0200
  Re: [PATCH v3 2/2] hwmon: (ltq-cputemp) add devicetree bindings  documentation Guenter Roeck <linux@roeck-us.net> - 2017-09-13 16:20 +0200

csiph-web