Messages in this thread | | | Date | Thu, 03 Dec 2015 16:11:20 +0000 | From | Martyn Welch <> | Subject | Re: [PATCH 1/3] Device tree binding documentation for chromeos-firmware |
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On 03/12/15 15:08, Rob Herring wrote: > On Thu, Dec 3, 2015 at 4:14 AM, Martyn Welch > <martyn.welch@collabora.co.uk> wrote: >> >> On 02/12/15 15:15, Rob Herring wrote: >>> >>> On Tue, Dec 01, 2015 at 07:12:49PM +0000, Martyn Welch wrote: >>>> >>>> This patch adds documentation for the chromeos-firmware binding. >>>> >>>> Cc: Rob Herring <robh+dt@kernel.org> >>>> Cc: Pawel Moll <pawel.moll@arm.com> >>>> Cc: Mark Rutland <mark.rutland@arm.com> >>>> Cc: Ian Campbell <ijc+devicetree@hellion.org.uk> >>>> Cc: Kumar Gala <galak@codeaurora.org> >>>> Cc: devicetree@vger.kernel.org >>>> Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk> >>>> --- >>>> .../devicetree/bindings/misc/chromeos-firmware.txt | 27 >>>> ++++++++++++++++++++++ >>> >>> >>> bindings/firmware/ please. >>> >>>> 1 file changed, 27 insertions(+) >>>> create mode 100644 >>>> Documentation/devicetree/bindings/misc/chromeos-firmware.txt >>>> >>>> diff --git a/Documentation/devicetree/bindings/misc/chromeos-firmware.txt >>>> b/Documentation/devicetree/bindings/misc/chromeos-firmware.txt >>>> new file mode 100644 >>>> index 0000000..8240611 >>>> --- /dev/null >>>> +++ b/Documentation/devicetree/bindings/misc/chromeos-firmware.txt >>>> @@ -0,0 +1,27 @@ >> >> >> <snip> >> >>>> + >>>> +Each signal is represented as a sub-node of "chromeos_firmware": >>>> +Subnode properties: >>>> + >>>> + - gpios: OF device-tree gpio specification. >>>> + >>>> +Example nodes: >>>> + >>>> + chromeos_firmware { >>> >>> >>> This should go under /firmware >>> >> >> I've changed this to be: >> >> firmware { >> chromeos { >> ... >> }; >> ]; >> >> Which I generally accept (assuming this is considered a part of the >> firmware) as a better way to represent this in the device tree, however this >> has the nasty side effect of causing the device tree parsing to avoid >> parsing the chromeos child and seeing it's compatible property (as the >> firmware node isn't a bus), resulting in the probe routine not being called. >> >> If I add a 'compatible = "simple-bus"' property to the firmware node it >> works, but this doesn't seem quite right as I believe "simple-bus" is >> defined as a "simple memory mapped bus". >> >> I /could/ rewrite the initialisation to call of_find_compatible_node(), but >> this seems rather hacky and inefficient. I can think of 2 other ways this >> could be resolved: >> >> (1) As this is only tangentially related to firmware, I rename it something >> like "chromeos-signals" and make it it's own node. In essence this driver >> provides a mechanism built on top of specific GPIO (ala gpio-keys seems to >> be, after-all this has a similar use of resources to that). > > I'm starting to fail to understand the relationship to firmware here... > > gpio-keys are at least a thing (being a key or set of keys). Your > grouping is a rather random collection of GPIOs. Maybe you need > "gpio-switch" binding and then the function would be "label" property. >
So, something like this:
gpio-switch { compatible = "gpio-switch";
pinctrl-names = "default"; pinctrl-0 = <&wp_gpio &dev_mode &rec_mode>;
write-protect { label = "write-protect"; gpios = <&gpx3 0 GPIO_ACTIVE_LOW>; read-only; };
developer-switch { label = "developer-switch"; gpios = <&gpx1 3 GPIO_ACTIVE_HIGH>; read-only; };
recovery-switch { label = "recovery-switch"; gpios = <&gpx0 7 GPIO_ACTIVE_LOW>; read-only; }; };
(Making it much more generic in the process.)
>> (2) Add a compatible string something like 'compatible="logical-group";' to >> the firmware node and add that too the bus matching logic. This would have >> the advantage of solving this in the general case (I guess there are other >> instances where a grouping of things more logically rather than physically >> connected would ideally be grouped together), though I expect there may be >> some strong views regarding this approach. > > Why do you need them grouped? >
That's effectively what is achieved by putting this (and I assume anything else considered "firmware" under a firmware node isn't it? (or and I miss-understanding your request?)
I think it is a moot point, I'll rework as you've suggested.
Martyn
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