c7b552df87
USB accessory mode allows users to connect USB host hardware specifically designed for Android-powered devices. The accessories must adhere to the Android accessory protocol outlined in the http://accessories.android.com documentation. This allows Android devices that cannot act as a USB host to still interact with USB hardware. When an Android device is in USB accessory mode, the attached Android USB accessory acts as the host, provides power to the USB bus, and enumerates connected devices. Bug: 63740241 Bug: 120441124 Change-Id: I67964b50d278f3c0471d47efbb7b0973a3502681 [badhri: f_accessory is being migrated to userspace.] Signed-off-by: Mike Lockwood <lockwood@android.com> [AmitP: Folded following android-4.9 commit changes into this patch ceb2f0aac624 ("ANDROID: usb: gadget: accessory: Fix section mismatch") Parts of e27543931009 ("ANDROID: usb: gadget: Fixes and hacks to make android usb gadget compile on 3.8") 1b07ec751563 ("ANDROID: drivers: usb: gadget: 64-bit related type fixes")] Signed-off-by: Amit Pundir <amit.pundir@linaro.org> [astrachan: Folded the following changes into this patch: 9d5891d516e2 ("ANDROID: usb: gadget: f_accessory: Add ACCESSORY_SET_AUDIO_MODE control request and ioctl") dc66cfce9622 ("ANDROID: usb: gadget: f_accessory: Add support for HID input devices") 5f1ac9c2871b ("ANDROID: usb: gadget: f_accessory: move userspace interface to uapi") 9a6241722cd8 ("ANDROID: usb: gadget: f_accessory: Enabled Zero Length Packet (ZLP) for acc_write") 31a0ecd5a825 ("ANDROID: usb: gadget: f_accessory: check for accessory device before disconnecting HIDs") 580721fa6cbc ("ANDROID: usb: gadget: f_accessory: Migrate to USB_FUNCTION API") 7f407172fb28 ("ANDROID: usb: gadget: f_accessory: Fix for UsbAccessory clean unbind.") ebc98ac5a22f ("ANDROID: usb: gadget: f_accessory: fix false disconnect due to a signal sent to the reading process") 71c6dc5ffdab ("ANDROID: usb: gadget: f_accessory: assign no-op request complete callbacks") 675047ee68e9 ("ANDROID: usb: gadget: f_accessory: Move gadget functions code") b2bedaa5c7df ("CHROMIUM: usb: gadget: f_accessory: add .raw_request callback")] Signed-off-by: Alistair Strachan <astrachan@google.com>
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.