On Mon, Dec 03, 2018 at 11:45:11AM +0800, Yu Chen wrote: > This patch adds notifier for drivers want to be informed of the usb role > switch.
I think in this case it would be good to explain a little for what we need the notifier for. > Cc: Greg Kroah-Hartman <[email protected]> > Cc: Heikki Krogerus <[email protected]> > Cc: Hans de Goede <[email protected]> > Cc: Andy Shevchenko <[email protected]> > Cc: John Stultz <[email protected]> > Signed-off-by: Heikki Krogerus <[email protected]> > Signed-off-by: Yu Chen <[email protected]> > > -- > v0: > The patch is provided by Heikki Krogerus. I modified and test it > on Hikey960 platform. I don't think I actually made a "patch" for this. The "diff" I made showing the idea does not count, so you should not sign off the patch with my address. In this case I believe something like "Suggested-by" should be used instead of SoB tag: Suggested-by: Heikki Krogerus <[email protected]> Side note: If this was from me, then there should be "from" line with my address as well. > -- > --- > drivers/usb/common/roles.c | 20 +++++++++++++++++++- > include/linux/usb/role.h | 46 > ++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 65 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/common/roles.c b/drivers/usb/common/roles.c > index 0f48090c5c30..bfd7a988b64c 100644 > --- a/drivers/usb/common/roles.c > +++ b/drivers/usb/common/roles.c > @@ -21,6 +21,7 @@ struct usb_role_switch { > struct device dev; > struct mutex lock; /* device lock*/ > enum usb_role role; > + struct blocking_notifier_head nh; > > /* From descriptor */ > struct device *usb2_port; > @@ -50,8 +51,10 @@ int usb_role_switch_set_role(struct usb_role_switch *sw, > enum usb_role role) > mutex_lock(&sw->lock); > > ret = sw->set(sw->dev.parent, role); > - if (!ret) > + if (!ret) { > sw->role = role; > + blocking_notifier_call_chain(&sw->nh, role, NULL); > + } > > mutex_unlock(&sw->lock); > > @@ -59,6 +62,20 @@ int usb_role_switch_set_role(struct usb_role_switch *sw, > enum usb_role role) > } > EXPORT_SYMBOL_GPL(usb_role_switch_set_role); > > +int usb_role_switch_register_notifier(struct usb_role_switch *sw, > + struct notifier_block *nb) > +{ > + return blocking_notifier_chain_register(&sw->nh, nb); > +} > +EXPORT_SYMBOL_GPL(usb_role_switch_register_notifier); > + > +int usb_role_switch_unregister_notifier(struct usb_role_switch *sw, > + struct notifier_block *nb) > +{ > + return blocking_notifier_chain_unregister(&sw->nh, nb); > +} > +EXPORT_SYMBOL_GPL(usb_role_switch_unregister_notifier); > + > /** > * usb_role_switch_get_role - Get the USB role for a switch > * @sw: USB role switch > @@ -297,6 +314,7 @@ usb_role_switch_register(struct device *parent, > return ERR_PTR(-ENOMEM); > > mutex_init(&sw->lock); > + BLOCKING_INIT_NOTIFIER_HEAD(&sw->nh); > > sw->allow_userspace_control = desc->allow_userspace_control; > sw->usb2_port = desc->usb2_port; > diff --git a/include/linux/usb/role.h b/include/linux/usb/role.h > index edc51be4a77c..c97d4be91ada 100644 > --- a/include/linux/usb/role.h > +++ b/include/linux/usb/role.h > @@ -40,6 +40,8 @@ struct usb_role_switch_desc { > bool allow_userspace_control; > }; > > + > +#if IS_ENABLED(CONFIG_USB_ROLE_SWITCH) > int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role); > enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw); > struct usb_role_switch *usb_role_switch_get(struct device *dev); > @@ -49,5 +51,49 @@ struct usb_role_switch * > usb_role_switch_register(struct device *parent, > const struct usb_role_switch_desc *desc); > void usb_role_switch_unregister(struct usb_role_switch *sw); > +int usb_role_switch_register_notifier(struct usb_role_switch *sw, > + struct notifier_block *nb); > +int usb_role_switch_unregister_notifier(struct usb_role_switch *sw, > + struct notifier_block *nb); > +#else > +static inline int usb_role_switch_set_role(struct usb_role_switch *sw, > + enum usb_role role) > +{ > + return 0; > +} > + > +static inline enum usb_role usb_role_switch_get_role(struct usb_role_switch > *sw) > +{ > + return USB_ROLE_NONE; > +} > + > +static inline struct usb_role_switch *usb_role_switch_get(struct device *dev) > +{ > + return ERR_PTR(-ENODEV); > +} > + > +static inline void usb_role_switch_put(struct usb_role_switch *sw) { } > + > +static inline struct usb_role_switch * > +usb_role_switch_register(struct device *parent, > + const struct usb_role_switch_desc *desc) > +{ > + return ERR_PTR(-ENODEV); > +} > + > +static inline void usb_role_switch_unregister(struct usb_role_switch *sw) { } > + > +static int usb_role_switch_register_notifier(struct usb_role_switch *sw, > + struct notifier_block *nb) > +{ > + return -ENODEV; > +} > + > +static int usb_role_switch_unregister_notifier(struct usb_role_switch *sw, > + struct notifier_block *nb) > +{ > + return -ENODEV; > +} > +#endif > > #endif /* __LINUX_USB_ROLE_H */ > -- > 2.15.0-rc2 thanks, -- heikki
