On Fri, Jul 15, 2016 at 11:10:45PM +0200, Rafał Miłecki wrote:
> This commit adds a new trigger that can turn on LED when USB device gets
> connected to the USB port. This can be useful for various home routers
> that have USB port and a proper LED telling user a device is connected.
>
> Right now this trigger is usable with a proper DT only, there isn't a
> way to specify USB ports from user space. This may change in a future.
>
> Signed-off-by: Rafał Miłecki <zajec5@xxxxxxxxx>
> ---
> V2: The first version got support for specifying list of USB ports from
> user space only. There was a (big try &) discussion on adding DT
> support. It led to a pretty simple solution of comparing of_node of
> usb_device to of_node specified in usb-ports property.
> Since it appeared DT support may be simpler and non-DT a bit more
> complex, this version drops previous support for "ports" and
> "new_port" and focuses on DT only. The plan is to see if this
> solution with DT is OK, get it accepted and then work on non-DT.
>
> Felipe: if there won't be any objections I'd like to ask for your Ack.
> ---
> Documentation/devicetree/bindings/leds/common.txt | 11 ++
> Documentation/leds/ledtrig-usbport.txt | 19 ++
> drivers/leds/trigger/Kconfig | 8 +
> drivers/leds/trigger/Makefile | 1 +
> drivers/leds/trigger/ledtrig-usbport.c | 206 ++++++++++++++++++++++
> 5 files changed, 245 insertions(+)
> create mode 100644 Documentation/leds/ledtrig-usbport.txt
> create mode 100644 drivers/leds/trigger/ledtrig-usbport.c
>
> diff --git a/Documentation/devicetree/bindings/leds/common.txt b/Documentation/devicetree/bindings/leds/common.txt
> index af10678..75536f7 100644
> --- a/Documentation/devicetree/bindings/leds/common.txt
> +++ b/Documentation/devicetree/bindings/leds/common.txt
> @@ -50,6 +50,12 @@ property can be omitted.
> For controllers that have no configurable timeout the flash-max-timeout-us
> property can be omitted.
>
> +Trigger specific properties for child nodes:
> +
> +usbport trigger:
> +- usb-ports : List of USB ports that usbport should observed for turning on a
> + given LED.
I think this should be more generic such that it could work for disk or
network LEDs too. Perhaps 'led-triggers = <nodes>'? trigger is a bit of
a Linux name, but I haven't thought of anything better. Really, I'd
prefer the link in the other direction (e.g. port node have a 'leds" or
'*-leds' property), but that's maybe harder to parse.
> +
> Examples:
>
> system-status {
> @@ -58,6 +64,11 @@ system-status {
> ...
> };
>
> +usb {
> + label = "USB";
It's not really clear in the example this is an LED node as it is
incomplete.
> + usb-ports = <&ohci_port1>, <&ehci_port1>;
> +};
> +
> camera-flash {
> label = "Flash";
> led-sources = <0>, <1>;
> diff --git a/Documentation/leds/ledtrig-usbport.txt b/Documentation/leds/ledtrig-usbport.txt
> new file mode 100644
> index 0000000..642c4cd
> --- /dev/null
> +++ b/Documentation/leds/ledtrig-usbport.txt
> @@ -0,0 +1,19 @@
> +USB port LED trigger
> +====================
> +
> +This LED trigger can be used for signaling user a presence of USB device in a
> +given port. It simply turns on LED when device appears and turns it off when it
> +disappears.
> +
> +It requires specifying a list of USB ports that should be observed. This can be
> +done in DT by setting a proper property with list of a phandles. If more than
> +one port is specified, LED will be turned on as along as there is at least one
> +device connected to any of ports.
> +
> +This trigger can be activated from user space on led class devices as shown
> +below:
> +
> + echo usbport > trigger
Why do I have to do this (by default)? I already specified in the DT
what the connection is. It should come up working OOTB, or don't put it
in DT.
> +Nevertheless, current there isn't a way to specify list of USB ports from user
> +space.
s/current/currently/
This is a problem since if it works by default and you switch to a
different trigger, there's no way to get back to the default (unless
you remember the ports).
Rob
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