Commit 8bc06364 authored by Matthias Kaehlcke's avatar Matthias Kaehlcke Committed by Greg Kroah-Hartman
Browse files

usb: misc: Add onboard_usb_hub driver 



The main issue this driver addresses is that a USB hub needs to be
powered before it can be discovered. For discrete onboard hubs (an
example for such a hub is the Realtek RTS5411) this is often solved
by supplying the hub with an 'always-on' regulator, which is kind
of a hack. Some onboard hubs may require further initialization
steps, like changing the state of a GPIO or enabling a clock, which
requires even more hacks. This driver creates a platform device
representing the hub which performs the necessary initialization.
Currently it only supports switching on a single regulator, support
for multiple regulators or other actions can be added as needed.
Different initialization sequences can be supported based on the
compatible string.

Besides performing the initialization the driver can be configured
to power the hub off during system suspend. This can help to extend
battery life on battery powered devices which have no requirements
to keep the hub powered during suspend. The driver can also be
configured to leave the hub powered when a wakeup capable USB device
is connected when suspending, and power it off otherwise.

Technically the driver consists of two drivers, the platform driver
described above and a very thin USB driver that subclasses the
generic driver. The purpose of this driver is to provide the platform
driver with the USB devices corresponding to the hub(s) (a hub
controller may provide multiple 'logical' hubs, e.g. one to support
USB 2.0 and another for USB 3.x).

Co-developed-by: default avatarRavi Chandra Sadineni <ravisadineni@chromium.org>
Reviewed-by: default avatarDouglas Anderson <dianders@chromium.org>
Signed-off-by: default avatarRavi Chandra Sadineni <ravisadineni@chromium.org>
Signed-off-by: default avatarMatthias Kaehlcke <mka@chromium.org>
Link: https://lore.kernel.org/r/20220630123445.v24.3.I7c9a1f1d6ced41dd8310e8a03da666a32364e790@changeid


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent dee6719e

Documentation/ABI/testing/sysfs-bus-platform-onboard-usb-hub

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What:		/sys/bus/platform/devices/<dev>/always_powered_in_suspend

Date:		June 2022

KernelVersion:	5.20

Contact:	Matthias Kaehlcke <matthias@kaehlcke.net>

		linux-usb@vger.kernel.org

Description:

		(RW) Controls whether the USB hub remains always powered

		during system suspend or not.
 
 No newline at end of file

MAINTAINERS

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@@ -14848,6 +14848,13 @@ S: Maintained 
T:	git git://linuxtv.org/media_tree.git

F:	drivers/media/i2c/ov9734.c









ONBOARD USB HUB DRIVER









M:	Matthias Kaehlcke <mka@chromium.org>









L:	linux-usb@vger.kernel.org









S:	Maintained









F:	Documentation/ABI/testing/sysfs-bus-platform-onboard-usb-hub









F:	drivers/usb/misc/onboard_usb_hub.c

















ONENAND FLASH DRIVER









M:	Kyungmin Park <kyungmin.park@samsung.com>









L:	linux-mtd@lists.infradead.org
































drivers/usb/core/Makefile



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@@ -12,6 +12,10 @@ usbcore-$(CONFIG_OF)		+= of.o







usbcore-$(CONFIG_USB_PCI)		+= hcd-pci.o









usbcore-$(CONFIG_ACPI)		+= usb-acpi.o



















ifdef CONFIG_USB_ONBOARD_HUB









usbcore-y			+= ../misc/onboard_usb_hub_pdevs.o









endif



















obj-$(CONFIG_USB)		+= usbcore.o



















obj-$(CONFIG_USB_LEDS_TRIGGER_USBPORT)	+= ledtrig-usbport.o
























drivers/usb/misc/Kconfig



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@@ -295,3 +295,19 @@ config BRCM_USB_PINMAP







	  This option enables support for remapping some USB external









	  signals, which are typically on dedicated pins on the chip,









	  to any gpio.



















config USB_ONBOARD_HUB









	tristate "Onboard USB hub support"









	depends on OF || COMPILE_TEST









	help









	  Say Y here if you want to support discrete onboard USB hubs that









	  don't require an additional control bus for initialization, but









	  need some non-trivial form of initialization, such as enabling a









	  power regulator. An example for such a hub is the Realtek









	  RTS5411.



















	  This driver can be used as a module but its state (module vs









	  builtin) must match the state of the USB subsystem. Enabling









	  this config will enable the driver and it will automatically









	  match the state of the USB subsystem. If this driver is a









	  module it will be called onboard_usb_hub.
























drivers/usb/misc/Makefile



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@@ -33,3 +33,4 @@ obj-$(CONFIG_USB_CHAOSKEY)		+= chaoskey.o







obj-$(CONFIG_USB_SISUSBVGA)		+= sisusbvga/









obj-$(CONFIG_USB_LINK_LAYER_TEST)	+= lvstest.o









obj-$(CONFIG_BRCM_USB_PINMAP)		+= brcmstb-usb-pinmap.o









obj-$(CONFIG_USB_ONBOARD_HUB)		+= onboard_usb_hub.o