On Fri, Mar 29, 2019 at 12:14:05PM +0800, Yu Chen wrote:
> This patch adds notifier for drivers want to be informed of the usb role
> switch.
>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
> Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> Cc: John Stultz <john.stultz@xxxxxxxxxx>
> Suggested-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Signed-off-by: Yu Chen <chenyu56@xxxxxxxxxx>
Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> ---
> v5:
> * Split the patch into two patches, the first one introduces stubs for the
> exiting functions, and this patch adds notifier functions.
> ---
> ---
> drivers/usb/roles/class.c | 20 +++++++++++++++++++-
> include/linux/usb/role.h | 16 ++++++++++++++++
> 2 files changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
> index f45d8df5cfb8..e2caaa665d6e 100644
> --- a/drivers/usb/roles/class.c
> +++ b/drivers/usb/roles/class.c
> @@ -20,6 +20,7 @@ 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;
> @@ -49,8 +50,10 @@ 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);
>
> @@ -58,6 +61,20 @@ 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
> @@ -271,6 +288,7 @@ 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 da2b9641b877..99d8b8e4fe61 100644
> --- a/include/linux/usb/role.h
> +++ b/include/linux/usb/role.h
> @@ -53,6 +53,10 @@ 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)
> @@ -80,6 +84,18 @@ usb_role_switch_register(struct device *parent,
> }
>
> 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
