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This commit adds a new trigger responsible for turning on LED when USB device gets connected to the selected USB port. This can can useful for various home routers that have USB port(s) and a proper LED telling user a device is connected. The trigger gets its documentation file but basically it just requires enabling it and selecting USB ports (e.g. echo 1 > ports/usb1-1). There was a long discussion on design of this driver. Its current state is a result of picking them most adjustable solution as others couldn't handle all cases. 1) It wasn't possible for the driver to register separated trigger for each USB port. Some physical USB ports are handled by more than one controller and so by more than one USB port. E.g. USB 2.0 physical port may be handled by OHCI's port and EHCI's port. It's also not possible to assign more than 1 trigger to a single LED and implementing such feature would be tricky due to syncing triggers and sysfs conflicts with old triggers. 2) Another idea was to register trigger per USB hub. This wouldn't allow handling devices with multiple USB LEDs and controllers (hubs) controlling more than 1 physical port. It's common for hubs to have few ports and each may have its own LED. This final trigger is highly flexible. It allows selecting any USB ports for any LED. It was also modified (comparing to the initial version) to allow choosing ports rather than having user /guess/ proper names. It was successfully tested on SmartRG SR400ac which has 3 USB LEDs, 2 physical ports and 3 controllers. It was noted USB subsystem already has usb-gadget and usb-host triggers but they are pretty trivial ones. They indicate activity only and can't have ports specified. In future it may be good idea to consider adding activity support to usbport as well. This should allow switching to this more generic driver and maybe marking old ones as obsolete. This can be implemented with another sysfs file for setting mode. The default mode wouldn't change so there won't be ABI breakage and so such feature can be safely implemented later. There was also an idea of supporting other devices (PCI, SDIO, etc.) but as this driver already contains some USB specific code (and will get more) these should be probably separated drivers (triggers). Signed-off-by: Rafał Miłecki <rafal@milecki.pl> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| .. | ||
| atm | ||
| c67x00 | ||
| chipidea | ||
| class | ||
| common | ||
| core | ||
| dwc2 | ||
| dwc3 | ||
| early | ||
| gadget | ||
| host | ||
| image | ||
| isp1760 | ||
| misc | ||
| mon | ||
| musb | ||
| phy | ||
| renesas_usbhs | ||
| serial | ||
| storage | ||
| usbip | ||
| wusbcore | ||
| Kconfig | ||
| Makefile | ||
| README | ||
| usb-skeleton.c | ||
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("hub_wq").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
../input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
../media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
../net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.