[v3,3/5] usb: gadget: Add function wakeup support

A function which is in function suspend state has to send a
function wake notification to the host in case it needs to
exit from this state and resume data transfer. Add support to
handle such requests by exposing a new gadget op.

Signed-off-by: Elson Roy Serrao <quic_eserrao@quicinc.com>
---
 drivers/usb/gadget/composite.c | 26 ++++++++++++++++++++++++++
 drivers/usb/gadget/udc/core.c  | 19 +++++++++++++++++++
 include/linux/usb/composite.h  |  6 ++++++
 include/linux/usb/gadget.h     |  4 ++++
 4 files changed, 55 insertions(+)

On Mon, Feb 06, 2023, Elson Roy Serrao wrote:
> A function which is in function suspend state has to send a
> function wake notification to the host in case it needs to
> exit from this state and resume data transfer. Add support to
> handle such requests by exposing a new gadget op.
> 
> Signed-off-by: Elson Roy Serrao <quic_eserrao@quicinc.com>
> ---
>  drivers/usb/gadget/composite.c | 26 ++++++++++++++++++++++++++
>  drivers/usb/gadget/udc/core.c  | 19 +++++++++++++++++++
>  include/linux/usb/composite.h  |  6 ++++++
>  include/linux/usb/gadget.h     |  4 ++++
>  4 files changed, 55 insertions(+)
> 
> diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> index e459fb0..aa243d8 100644
> --- a/drivers/usb/gadget/composite.c
> +++ b/drivers/usb/gadget/composite.c
> @@ -492,6 +492,32 @@ int usb_interface_id(struct usb_configuration *config,
>  }
>  EXPORT_SYMBOL_GPL(usb_interface_id);
>  
> +int usb_func_wakeup(struct usb_function *func)
> +{
> +	int ret, id;
> +
> +	if (!func->func_rw_armed) {
> +		ERROR(func->config->cdev, "func remote wakeup not enabled\n");
> +		return -EINVAL;
> +	}
> +
> +	DBG(func->config->cdev, "%s function wakeup\n", func->name);

Do we need this DBG print?

> +
> +	for (id = 0; id < MAX_CONFIG_INTERFACES; id++)
> +		if (func->config->interface[id] == func)
> +			break;
> +
> +	if (id == MAX_CONFIG_INTERFACES) {
> +		ERROR(func->config->cdev, "Invalid function id:%d\n", id);
> +		return -EINVAL;
> +	}
> +
> +	ret = usb_gadget_func_wakeup(func->config->cdev->gadget, id);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(usb_func_wakeup);
> +
>  static u8 encode_bMaxPower(enum usb_device_speed speed,
>  		struct usb_configuration *c)
>  {
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 5874d4f..63b5944 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -846,6 +846,25 @@ int usb_gadget_activate(struct usb_gadget *gadget)
>  }
>  EXPORT_SYMBOL_GPL(usb_gadget_activate);
>  
> +/**
> + * usb_gadget_func_wakeup - sends function wake notification to the host.
> + * If the link is in low power state, first brings the link to active state.
> + * @gadget: controller used to wake up the host
> + * @interface_id: interface on which function wake notification is sent.
> + *
> + * Returns zero on success, else negative error code if the hardware

On completion, the device notification is sent? So it's a synchonous
call right? Probably can't be called in interrupt context? Can you
document the expectation here.

Thanks,
Thinh

> + * doesn't support such attempts. Drivers must return device descriptors that
> + * report their ability to support this, or hosts won't enable it.
> + */
> +int usb_gadget_func_wakeup(struct usb_gadget *gadget, int intf_id)
> +{
> +	if (!gadget->ops->func_wakeup)
> +		return -EOPNOTSUPP;
> +
> +	return gadget->ops->func_wakeup(gadget, intf_id);
> +}
> +EXPORT_SYMBOL_GPL(usb_gadget_func_wakeup);
> +
>  /* ------------------------------------------------------------------------- */
>  
>  #ifdef	CONFIG_HAS_DMA
> diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
> index 91d22c3..c9573ba 100644
> --- a/include/linux/usb/composite.h
> +++ b/include/linux/usb/composite.h
> @@ -150,6 +150,9 @@ struct usb_os_desc_table {
>   *	GetStatus() request when the recipient is Interface.
>   * @func_suspend: callback to be called when
>   *	SetFeature(FUNCTION_SUSPEND) is reseived
> + * @func_suspended: Indicates whether the function is in function suspend state.
> + * @func_rw_armed: Indicates whether the function is armed by the host for
> + *	wakeup signaling.
>   *
>   * A single USB function uses one or more interfaces, and should in most
>   * cases support operation at both full and high speeds.  Each function is
> @@ -220,6 +223,8 @@ struct usb_function {
>  	int			(*get_status)(struct usb_function *);
>  	int			(*func_suspend)(struct usb_function *,
>  						u8 suspend_opt);
> +	bool			func_suspended;
> +	bool			func_rw_armed;
>  	/* private: */
>  	/* internals */
>  	struct list_head		list;
> @@ -241,6 +246,7 @@ int config_ep_by_speed_and_alt(struct usb_gadget *g, struct usb_function *f,
>  
>  int config_ep_by_speed(struct usb_gadget *g, struct usb_function *f,
>  			struct usb_ep *_ep);
> +int usb_func_wakeup(struct usb_function *func);
>  
>  #define	MAX_CONFIG_INTERFACES		16	/* arbitrary; max 255 */
>  
> diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
> index 05d1449..1e73943 100644
> --- a/include/linux/usb/gadget.h
> +++ b/include/linux/usb/gadget.h
> @@ -309,6 +309,7 @@ struct usb_udc;
>  struct usb_gadget_ops {
>  	int	(*get_frame)(struct usb_gadget *);
>  	int	(*wakeup)(struct usb_gadget *);
> +	int     (*func_wakeup)(struct usb_gadget *gadget, int intf_id);
>  	int	(*set_remotewakeup)(struct usb_gadget *, int set);
>  	int	(*set_selfpowered) (struct usb_gadget *, int is_selfpowered);
>  	int	(*vbus_session) (struct usb_gadget *, int is_active);
> @@ -616,6 +617,7 @@ int usb_gadget_disconnect(struct usb_gadget *gadget);
>  int usb_gadget_deactivate(struct usb_gadget *gadget);
>  int usb_gadget_activate(struct usb_gadget *gadget);
>  int usb_gadget_check_config(struct usb_gadget *gadget);
> +int usb_gadget_func_wakeup(struct usb_gadget *gadget, int intf_id);
>  #else
>  static inline int usb_gadget_frame_number(struct usb_gadget *gadget)
>  { return 0; }
> @@ -643,6 +645,8 @@ static inline int usb_gadget_activate(struct usb_gadget *gadget)
>  { return 0; }
>  static inline int usb_gadget_check_config(struct usb_gadget *gadget)
>  { return 0; }
> +static inline int usb_gadget_func_wakeup(struct usb_gadget *gadget, int intf_id)
> +{ return 0; }
>  #endif /* CONFIG_USB_GADGET */
>  
>  /*-------------------------------------------------------------------------*/
> -- 
> 2.7.4
>