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    SubjectRe: [PATCH v3 3/5] usb: gadget: Add function wakeup support
    Date
    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
    >
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