usb: phy: add usb phy notify port status API

In Realtek SoC, the parameter of usb phy is designed to can dynamic
tuning base on port status. Therefore, add a notify callback of phy
driver when usb port status change.

The Realtek phy driver is designed to dynamically adjust disconnection
level and calibrate phy parameters. When the device connected bit changes
and when the disconnected bit changes, do port status change notification:

Check if portstatus is USB_PORT_STAT_CONNECTION and portchange is
USB_PORT_STAT_C_CONNECTION.
1. The device is connected, the driver lowers the disconnection level and
calibrates the phy parameters.
2. The device disconnects, the driver increases the disconnect level and
calibrates the phy parameters.

When controller to notify connect that device is already ready. If we
adjust the disconnection level in notify_connect, the disconnect may have
been triggered at this stage. So we need to change that as early as
possible. The status change of connection is before port reset.
Therefore, we add an api to notify phy the port status changes. In this
stage, the device is not port enable, and it will not trigger
disconnection.

Signed-off-by: Stanley Chang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/core/hub.c

···
 		ret = 0;
 	}
 	mutex_unlock(&hub->status_mutex);
+
+	/*
+	 * There is no need to lock status_mutex here, because status_mutex
+	 * protects hub->status, and the phy driver only checks the port
+	 * status without changing the status.
+	 */
+	if (!ret) {
+		struct usb_device *hdev = hub->hdev;
+
+		/*
+		 * Only roothub will be notified of port state changes,
+		 * since the USB PHY only cares about changes at the next
+		 * level.
+		 */
+		if (is_root_hub(hdev)) {
+			struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
+
+			if (hcd->usb_phy)
+				usb_phy_notify_port_status(hcd->usb_phy,
+							   port1 - 1, *status, *change);
+		}
+	}
+
 	return ret;
 }
 

include/linux/usb/phy.h

···
 	 */
 	int	(*set_wakeup)(struct usb_phy *x, bool enabled);
 
+	/* notify phy port status change */
+	int	(*notify_port_status)(struct usb_phy *x, int port,
+				      u16 portstatus, u16 portchange);
+
 	/* notify phy connect status change */
 	int	(*notify_connect)(struct usb_phy *x,
 			enum usb_device_speed speed);
···
 {
 	if (x && x->set_wakeup)
 		return x->set_wakeup(x, enabled);
+	else
+		return 0;
+}
+
+static inline int
+usb_phy_notify_port_status(struct usb_phy *x, int port, u16 portstatus, u16 portchange)
+{
+	if (x && x->notify_port_status)
+		return x->notify_port_status(x, port, portstatus, portchange);
 	else
 		return 0;
 }