linux-kernel - [PATCH 2/5] usb: gadget: Add function wakeup support

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Date:   Tue,  2 Aug 2022 12:18:37 -0700
From:   Elson Roy Serrao <quic_eserrao@...cinc.com>
To:     balbi@...nel.org, gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        quic_wcheng@...cinc.com, quic_jackp@...cinc.com,
        quic_mrana@...cinc.com, Thinh.Nguyen@...opsys.com,
        Elson Roy Serrao <quic_eserrao@...cinc.com>
Subject: [PATCH 2/5] usb: gadget: Add function wakeup support

An interface which is in function suspend state has to send a function
wakeup notification to the host in case it needs to initate any data
transfer. One notable difference between this and the existing remote
wakeup mechanism is that this can be called per-interface, and a UDC
would need to know the particular interface number to convey in its
Device Notification transaction packet.  Hence, we need to introduce
a new callback in the gadget_ops structure that UDC device drivers
can implement.  Similarly add a convenience function in the composite
driver which function drivers can call. Add support to handle such
requests in the composite layer and invoke the gadget op.

Signed-off-by: Elson Roy Serrao <quic_eserrao@...cinc.com>
---
 drivers/usb/gadget/composite.c | 32 ++++++++++++++++++++++++++++++++
 drivers/usb/gadget/udc/core.c  |  9 +++++++++
 include/linux/usb/composite.h  |  1 +
 include/linux/usb/gadget.h     |  2 ++
 4 files changed, 44 insertions(+)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 403563c..6bdce23 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -490,6 +490,38 @@ 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;
+	unsigned long flags;
+
+	if (!func || !func->config || !func->config->cdev ||
+	    !func->config->cdev->gadget)
+		return -EINVAL;
+
+	DBG(func->config->cdev, "%s function wakeup\n", func->name);
+
+	spin_lock_irqsave(&func->config->cdev->lock, flags);
+
+	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);
+		ret = -EINVAL;
+		goto err;
+	}
+
+	ret = usb_gadget_func_wakeup(func->config->cdev->gadget, id);
+
+err:
+	spin_unlock_irqrestore(&func->config->cdev->lock, flags);
+
+	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 7886497..fe5c504 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -816,6 +816,15 @@ int usb_gadget_activate(struct usb_gadget *gadget)
 }
 EXPORT_SYMBOL_GPL(usb_gadget_activate);
 
+int usb_gadget_func_wakeup(struct usb_gadget *gadget, int interface_id)
+{
+	if (gadget->speed < USB_SPEED_SUPER || !gadget->ops->func_wakeup)
+		return -EOPNOTSUPP;
+
+	return gadget->ops->func_wakeup(gadget, interface_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 9d27622..31b35d7 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -254,6 +254,7 @@ 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 3ad58b7..76f9de4 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -311,6 +311,7 @@ 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 interface_id);
 	int	(*set_selfpowered) (struct usb_gadget *, int is_selfpowered);
 	int	(*vbus_session) (struct usb_gadget *, int is_active);
 	int	(*vbus_draw) (struct usb_gadget *, unsigned mA);
@@ -612,6 +613,7 @@ 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 interface_id);
 #else
 static inline int usb_gadget_frame_number(struct usb_gadget *gadget)
 { return 0; }
-- 
2.7.4