On 30/05/16 12:29, Peter Chen wrote: > On Fri, May 13, 2016 at 01:03:14PM +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. >> NOTE: my am437x-gp-evm broke so I couldn't test v8 on it. >> But the changes since v7 are trivial and shouldn't impact am437x-gp-evm. >> >> DWC3 controller and platform related patches will be sent separately. >> >> Series is based on v4.6-rc1 and depends on first 2 patches of [1] >> [1] - OTG fsm cleanup - https://lkml.org/lkml/2016/3/30/186 >> >> 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); >> >> Changelog: >> --------- >> 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) >> > > Since you have agreed to move CONFIG_USB_OTG out of HCD, I suggest you > can have a folder to put current OTG and OTG_FSM stuffs under the root > of usb folder, it can benefit the user who wants to add their dual-role > switch driver or OTG driver. What do you think? Yes, I will give it a try and post if any problems. -- cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
