[PATCH v2 01/22] usb: typec: Add alternate mode state notifiers

[Joshua Peisach]

On Sun Sep 6, 2026 at 2:36 PM EDT, Sven Peter wrote:
> The Apple Silicon USB4/Thunderbolt driver needs to be made aware of
> cable details and whenever USB4 or Thunderbolt is entered. The cable
> details are already available as part of the typec subsystem but there
> is no way to get a notification on typec_altmode_update_active() so
> far.
>
> Add a blocking notifier chain to each alternate mode and call it
> whenever the mode is activated or deactivated right next to the already
> existing sysfs and kobject_uevent notifications. Replay activations when a
> notifier is registered.
>
> Signed-off-by: Sven Peter <sven at kernel.org>
> ---
>  drivers/usb/typec/bus.h   |  6 +++++
>  drivers/usb/typec/class.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/usb/typec.h | 16 +++++++++++++
>  3 files changed, 81 insertions(+)
>
> diff --git a/drivers/usb/typec/bus.h b/drivers/usb/typec/bus.h
> index 7df5deb1dd3a..4dc60c48c91e 100644
> --- a/drivers/usb/typec/bus.h
> +++ b/drivers/usb/typec/bus.h
> @@ -3,6 +3,8 @@
>  #ifndef __USB_TYPEC_ALTMODE_H__
>  #define __USB_TYPEC_ALTMODE_H__
>  
> +#include <linux/mutex.h>
> +#include <linux/notifier.h>
>  #include <linux/usb/typec_altmode.h>
>  
>  struct typec_mux;
> @@ -23,6 +25,10 @@ struct altmode {
>  
>  	struct altmode			*partner;
>  	struct altmode			*plug[2];
> +
> +	/* Serializes active state changes and notifier registration. */
> +	struct mutex			state_lock;
> +	struct blocking_notifier_head	state_notifier;
>  };
>  
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