Re: [PATCH v10 00/14] USB OTG/dual-role framework

[Peter Chen <hzpeterchen@gmail.com>]

On Fri, Jun 10, 2016 at 04:07:09PM +0300, Roger Quadros wrote:
> Hi,
> 
> This series centralizes OTG/Dual-role functionality in the kernel.
> As of now I've got Dual-role functionality working pretty reliably on
> dra7-evm and am437x-gp-evm.
> 
> DWC3 controller and TI platform related patches will be sent separately.
> 
> Series is based on v4.7-rc1 + balbi/usb.git testing/next
> commit 4a2786c10462df650965785462ca82c185164d98.
> 

Roger, I have acked for all your patches. You can send v11 for all
patches. When you get Felipe's ack for gadget part, Alan's ack
for hcd part, and your dwc3 and platform related patches ack,
you can let Felipe help to queue this patch set since some of
the code based on his tree. Thank you for your hard work for it.

Peter

> Why?:
> ----
> 
> Currently there is no central location where OTG/dual-role functionality is
> implemented in the Linux USB stack and every USB controller driver is
> doing their own thing for OTG/dual-role. We can benefit from code-reuse
> and simplicity by adding the OTG/dual-role core driver.
> 
> Newer OTG cores support standard host interface (e.g. xHCI) so
> host and gadget functionality are no longer closely knit like older
> cores. There needs to be a way to co-ordinate the operation of the
> host and gadget controllers in dual-role mode. i.e. to stop and start them
> from a central location. This central location should be the
> USB OTG/dual-role core.
> 
> Host and gadget controllers might be sharing resources and can't
> be always running. One has to be stopped for the other to run.
> This couldn't be done till now but can be done from the OTG core.
> 
> What?:
> -----
> 
> The OTG/dual-role core consists of a set of APIs that allow
> registration of OTG controller device and OTG capable host and gadget
> controllers.
> 
> - The OTG controller driver can provide the OTG capabilities and the
> Finite State Machine work function via 'struct usb_otg_config'
> at the time of registration i.e. usb_otg_register();
> 
> 	struct usb_otg *usb_otg_register(struct device *dev,
>         	                         struct usb_otg_config *config);
> 	int usb_otg_unregister(struct device *dev);
> 	/**
> 	 * struct usb_otg_config - otg controller configuration
> 	 * @caps: otg capabilities of the controller
> 	 * @ops: otg fsm operations
> 	 * @otg_work: optional custom otg state machine work function
> 	 */
> 	struct usb_otg_config {
> 	        struct usb_otg_caps *otg_caps;
> 	        struct otg_fsm_ops *fsm_ops;
> 	        void (*otg_work)(struct work_struct *work);
> 	};
> 
> The dual-role state machine is built-into the OTG core so nothing
> special needs to be provided if only dual-role functionality is desired.
> The low level OTG controller driver ops are povided via
> 'struct otg_fsm_ops *fsm_ops' in the 'struct usb_otg_config'.
> 
> After registration, the OTG core waits for host, gadget controller
> and the gadget function driver to be registered. Once all resources are
> available it instantiates the Finite State Machine (FSM).
> The host/gadget controllers are started/stopped according to the FSM.
> 
> - Host and gadget controllers that are a part of OTG/dual-role port must
> use the OTG core provided APIs to add/remove the host/gadget.
> i.e. hosts must use usb_otg_add_hcd() usb_otg_remove_hcd(),,
> gadgets must use usb_otg_add_gadget_udc() usb_del_gadget_udc().
> This ensures that the host and gadget controllers are not started till
> the state machine is ready and the right bus conditions are met.
> It also allows the host and gadget controllers to provide the OTG
> controller device to link them together. For Device tree boots
> the related OTG controller is automatically picked up via the
> 'otg-controller' property in the Host/Gadget controller nodes.
> 
> 	int usb_otg_add_hcd(struct usb_hcd *hcd,
> 			    unsigned int irqnum, unsigned long irqflags,
> 			    struct device *otg_dev);
> 	void usb_otg_remove_hcd(struct usb_hcd *hcd);
> 
> 	int usb_otg_add_gadget_udc(struct device *parent,
> 				   struct usb_gadget *gadget,
> 				   struct device *otg_dev);
> 	usb_del_gadget_udc() must be used for removal.
> 
> 
> - During the lifetime of the FSM, the OTG controller driver can provide
> inputs event changes using usb_otg_sync_inputs(). The OTG core will
> then schedule the FSM work function (or internal dual-role state machine)
> to update the FSM state. The FSM then calls the OTG controller
> operations (fsm_ops) as necessary.
> 	void usb_otg_sync_inputs(struct usb_otg *otg);
> 
> - The following 2 functions are provided as helpers for use by the
> OTG controller driver to start/stop the host/gadget controllers.
> 	int usb_otg_start_host(struct usb_otg *otg, int on);
> 	int usb_otg_start_gadget(struct usb_otg *otg, int on);
> 
> - The following function is provided for use by the USB host stack
> to sync OTG related events to the OTG state machine.
> e.g. change in host_bus->b_hnp_enable, gadget->b_hnp_enable
> 	int usb_otg_kick_fsm(struct device *otg_device);
> 
> - The following function is provided for use by the USB gadget stack
> to notify OTG/DRD about gadget function driver being ready/not-ready
> 	int usb_otg_gadget_ready(struct usb_gadget *gadget, bool ready)
> 
> Changelog:
> ---------
> v10:
> - added missing mutex_unlock in failure path in usb_otg_unregister()
> - removed unnecessary hrtimer.h and ktime.h in linux/usb/otg.h
> - comment fixes: urb->URB.
> - fix commit log: say dev_vdbg() instead of dev_dbg().
> - Update comments so that HCD means Host Controller Driver.
> - rebased on Felipe's balbi/usb.git /testing/next
> - include <linux/usb/of.h> in usb-otg.c
> - in usb_otg_start_host() check if hcd_ops->add() failed and return
> error code if it did.
> - in usb_otg_start/stop_gadget() check if hcd_ops->add() failed and return
> error code if it did.
> - follow kernel-doc style in usb-otg.c
> 
> v9:
> - In the DT bindings, clearly indicate which properties are for OTG controller
> and which ones are for host/device controllers
> - Removed host/gadget wait list from otg core. Use defer probing if host/gadget
> registers before dual-role/otg controller.
> - move gadget registering to otg core from udc_bind_to_driver()/usb_gadget_remove_driver()
> to usb_add_gadget_udc_release()/usb_del_gadget_udc(). This means that we need
> an additional mechanism to know when the gadget function driver registers.
> So we add usb_otg_gadget_ready() API to allow gadget to notify otg core about
> ready/not-ready function driver.
> - update otg->caps based on capabilities provided by the controller and the
> device tree overrides.
> - in usb_drd_work() we must keep calling the drd_statemachine() as long as
> there is a state change.
> - updated kconfig so that usbotg can be a module when both host and gadget
> are modules.
> - rebased on v4.7-rc1
> 
> v8:
> - split out start/stop gadget and connect/disconnect operations.
> - make CONFIG_OTG dpend on CONFIG_USB_GADGET as well apart from CONFIG_USB
> - use create_freezable_workqueue() for OTG work as per Peter's suggestion.
> - remove usb-otg.h as we're not initializing any OTG timers.
> - don't include unnecessary headers in usb-otg.c (i.e. hrtimer.h & ktime.h)
> 
> v7:
> - added dual-role support for host controllers requiring a companion
> controller. e.g. EHCI + OHCI.
> - added of_usb_get_otg() to get the OTG controller device
> from the USB controller's device node.
> - addressed review comments.
> 
> v6:
> - added otg specific APIs for host/gadget registration. behaviour of
> original host/gadget API remains unchanged. Platform devices can now
> pass the otg device explicitly while registering host/gadget.
> - moved hcd specific operations from struct otg_fsm to struct hcd_ops.
> - made struct usb_otg mandatory for all otg related APIs.
> - allow otg controller to provide it's own otg_work function so that
> it can implement it's own state machine.
> - removed otg fsm and timers from usb-otg.c. Only dual-role state machine
> is implemented.
> - vbus is controlled in the dual-role state machine.
> - PM runtime is used around drd_statemachine().
> - added otg_dev to xhci platform data to allow platform code to specify
> the otg controller tied to the xhci host controller.
> 
> v5: Internal version. Not sent to mailing list
> 
> v4:
> - Added DT support for tying otg-controller to host and gadget
>  controllers. For DT we no longer have the constraint that
>  OTG controller needs to be parent of host and gadget. They can be
>  tied together using the "otg-controller" property.
> - Relax the requirement for DT case that otg controller must register
>  before host/gadget. We maintain a wait list of host/gadget devices
>  waiting on the otg controller.
> - Use a single struct usb_otg for otg data.
> - Don't override host/gadget start/stop APIs. Let the controller
>  drivers do what they want as they know best. Helper API is provided
>  for controller start/stop that controller driver can use.
> - Introduce struct usb_otg_config to pass the otg capabilities,
>  otg ops and otg timer timeouts during otg controller registration.
> - rebased on Greg's usb.git/usb-next
> 
> v3:
> - all otg related definations now in otg.h
> - single kernel config USB_OTG to enable OTG core and FSM.
> - resolved symbol dependency issues.
> - use dev_vdbg instead of VDBG() in usb-otg-fsm.c
> - rebased on v4.2-rc1
> 
> v2:
> - Use add/remove_hcd() instead of start/stop_hcd() to enable/disable
>  the host controller
> - added dual-role-device (DRD) state machine which is a much simpler
>  mode of operation when compared to OTG. Here we don't support fancy
>  OTG features like HNP, SRP, on the fly role-swap. The mode of operation
>  is determined based on ID pin (cable type) and the role doesn't change
>  till the cable type changes.
> 
> --
> cheers,
> -roger
> 
> Roger Quadros (13):
>   usb: hcd: Initialize hcd->flags to 0
>   usb: otg-fsm: Prevent build warning "VDBG" redefined
>   usb: hcd.h: Add OTG to HCD interface
>   usb: otg-fsm: use usb_otg wherever possible
>   usb: otg-fsm: move host controller operations into usb_otg->hcd_ops
>   usb: gadget.h: Add OTG to gadget interface
>   usb: otg: get rid of CONFIG_USB_OTG_FSM in favour of CONFIG_USB_OTG
>   usb: otg: add OTG/dual-role core
>   usb: of: add an API to get OTG device from USB controller node
>   usb: otg: use dev_vdbg() instead of VDBG()
>   usb: hcd: Adapt to OTG core
>   usb: gadget: udc: adapt to OTG core
>   usb: host: xhci-plat: Add otg device to platform data
> 
> Yoshihiro Shimoda (1):
>   usb: otg: add hcd companion support
> 
>  Documentation/devicetree/bindings/usb/generic.txt |   6 +
>  Documentation/usb/chipidea.txt                    |   2 +-
>  drivers/usb/Kconfig                               |  18 +
>  drivers/usb/Makefile                              |   1 +
>  drivers/usb/chipidea/Makefile                     |   2 +-
>  drivers/usb/chipidea/ci.h                         |   3 +-
>  drivers/usb/chipidea/core.c                       |  14 +-
>  drivers/usb/chipidea/debug.c                      |   2 +-
>  drivers/usb/chipidea/otg_fsm.c                    | 176 +++--
>  drivers/usb/chipidea/otg_fsm.h                    |   2 +-
>  drivers/usb/chipidea/udc.c                        |  17 +-
>  drivers/usb/common/Makefile                       |   5 +-
>  drivers/usb/common/common.c                       |  27 +
>  drivers/usb/common/usb-otg-fsm.c                  | 203 ++---
>  drivers/usb/common/usb-otg.c                      | 919 ++++++++++++++++++++++
>  drivers/usb/core/Kconfig                          |  22 -
>  drivers/usb/core/hcd.c                            |  56 ++
>  drivers/usb/gadget/Kconfig                        |   1 +
>  drivers/usb/gadget/udc/core.c                     | 202 ++++-
>  drivers/usb/host/xhci-plat.c                      |  35 +-
>  drivers/usb/phy/Kconfig                           |   2 +-
>  drivers/usb/phy/phy-fsl-usb.c                     | 155 ++--
>  drivers/usb/phy/phy-fsl-usb.h                     |   3 +-
>  include/linux/usb/gadget.h                        |  22 +
>  include/linux/usb/hcd.h                           |  29 +
>  include/linux/usb/of.h                            |   9 +
>  include/linux/usb/otg-fsm.h                       | 154 +---
>  include/linux/usb/otg.h                           | 290 ++++++-
>  include/linux/usb/xhci_pdriver.h                  |   3 +
>  29 files changed, 1918 insertions(+), 462 deletions(-)
>  create mode 100644 drivers/usb/common/usb-otg.c
> 
> -- 
> 2.7.4
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-usb" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 

Best Regards,
Peter Chen