[v13,0/6] Add function suspend/resume and remote wakeup support

Changes in v13
 - Added function suspend feature selector handling and related functionalities
   in composite layer and removed them from f_ecm. This will also lay a generic
   framework for other functions to use.
   
Changes in v12
 - Added a new patch to arm the function for triggering remote wakeup based on the
   function suspend packet sent by the host. Also handle get_status in composite
   layer as default.
 - Removed set/reset of func_wakeup_armed flag in f_ecm and let composite layer
   handle it
 
Changes in v11
 - When ecm function suspend is called return negative error only if host is trying
   to arm for function wakeup and device is not wakeup capable.
   
Changes in v10
 - Modified the return value to 0 in ecm_get_status() so that device responds
   with both remote wakeup armed and remote wakeup capable bit reset to 0.
 - Return negative errno if wakeup is not supported when func suspend feature
   selector is sent by the host.

Changes in v9
 - Added bmAtrributes wakeup bit check for arming the function for function
   remote wakeup and also in get_status api

Changes in v8
 - Added else case to return error value while setting remote wakeup feature
   selector so that device will respond with a protocl stall

Changes in v7
 - Added a check to set device remote wakeup feature selector in ep0.c based on whether
   the device is configured for remote wakeup.
 - Commit message and usb_func_wakeup documentation changes.

Changes in v6
 - Combined usb_gadget_func_wakeup API with usb_func_wakeup API in composite layer
   so that there is only 1 API for triggering function remote wakeup for better error
   handling. Since function suspend is something specific to usb functions, better to
   keep the related APIs in composite layer and above. Also documented the usage and
   applicability of the usb_func_wakeup API.

Changes in v5
 - Add wakeup_armed check in patch2 in the link status change event handler
   so that resume gets triggeed only in the remote wakeup context.
 - Costmetic changes in patch3 and patch4

Changes in v4
 - Moved the wakeup bit check to bind function for warning the user at an early
   stage itself.
 - Added the remote wakeup configured check to gadget_wakeup() and func_wakeup()
   routines so that wakeup can be triggered only if user has configured it.
 - Cosmetic changes with respect to renaming the variables to reflect the operation
   better.

Changes in v3
 - Modified rw_capable flag to reflect the gadgets capability for wakeup
   signalling.
 - Added a check to configure wakeup bit in bmAttributes only if gadget
   is capable of triggering wakeup.
 - Implemented a gadget op for composite layer to inform UDC whether device
   is configured for remote wakeup.
 - Added a check in __usb_gadget_wakeup() API to trigger wakeup only if the
   device is configured for it.
 - Cosmetic changes in dwc3_gadget_func_wakeup() API.

Changes in v2
 - Added a flag to indicate whether the device is remote wakeup capable.
 - Added an async parameter to _dwc3_gadget_wakeup() API and few cosmetic
   changes.
 - Added flags to reflect the state of  function suspend and function remote
   wakeup to usb_function struct rather than function specific struct (f_ecm).
 - Changed the dwc3_gadget_func__wakeup() API to run synchronously by first
   checking the link state and then sending the device notification. Also
   added debug log for DEVICE_NOTIFICATION generic cmd.
 - Added changes to arm the device for remotewakeup/function remotewakeup
   only if device is capable.

An usb device can initate a remote wakeup and bring the link out of
suspend as dictated by the DEVICE_REMOTE_WAKEUP feature selector.
To achieve this an interface can invoke gadget_wakeup op and wait for the
device to come out of LPM. But the current polling based implementation
fails if the host takes a long time to drive the resume signaling specially
in high speed capable devices. Switching to an interrupt based approach is
more robust and efficient. This can be leveraged by enabling link status
change events and triggering a gadget resume when the link comes to active
state.

If the device is enhanced super-speed capable, individual interfaces can
also be put into suspend state. An interface can be in function suspend
state even when the device is not in suspend state. Function suspend state
is retained throughout the device suspend entry and exit process.
A function can be put to function suspend through FUNCTION_SUSPEND feature
selector sent by the host. This setup packet also decides whether that
function is capable of initiating a function remote wakeup. When the
function sends a wakeup notification to the host the link must be first
brought to a non-U0 state and then this notification is sent.

This change adds the infrastructure needed to support the above
functionalities.

Elson Roy Serrao (6):
  usb: gadget: Properly configure the device for remote wakeup
  usb: dwc3: Add remote wakeup handling
  usb: gadget: Add function wakeup support
  usb: dwc3: Add function suspend and function wakeup support
  usb: gadget: Handle function suspend feature selector
  usb: gadget: f_ecm: Add suspend/resume and remote wakeup support

 drivers/usb/dwc3/core.h               |   5 ++
 drivers/usb/dwc3/debug.h              |   2 +
 drivers/usb/dwc3/ep0.c                |  19 +++---
 drivers/usb/dwc3/gadget.c             | 118 ++++++++++++++++++++++++++++++--
 drivers/usb/gadget/composite.c        | 123 ++++++++++++++++++++++++++++++++--
 drivers/usb/gadget/configfs.c         |   3 +
 drivers/usb/gadget/function/f_ecm.c   |  22 ++++++
 drivers/usb/gadget/function/u_ether.c |  63 +++++++++++++++++
 drivers/usb/gadget/function/u_ether.h |   4 ++
 drivers/usb/gadget/udc/core.c         |  27 ++++++++
 drivers/usb/gadget/udc/trace.h        |   5 ++
 include/linux/usb/composite.h         |   8 +++
 include/linux/usb/gadget.h            |   9 +++
 13 files changed, 389 insertions(+), 19 deletions(-)