usb: ehci: prevent bad PORTSC register access

1. The 'index' of ehci_submit_root() is not always > 0.

   e.g.
   While it gets invoked from usb_get_descriptor(),
   the 'index' is always a '0'. (See ch.9 of USB2.0)

2. The PORTSC register is not always required, and thus it
   should only report a port error when necessary.
   It would cause a port scan failure if the ehci_submit_root()
   always gets terminated by a port error.

Signed-off-by: Kuo-Jung Su <dantesu@faraday-tech.com>
CC: Marek Vasut <marex@denx.de>

drivers/usb/host/ehci-hcd.c

@@ -616,11 +616,6 @@ ehci_submit_root(struct usb_device *dev, unsigned long pipe, void *buffer,
 	int port = le16_to_cpu(req->index) & 0xff;
 	struct ehci_ctrl *ctrl = dev->controller;
 
-	if (port > CONFIG_SYS_USB_EHCI_MAX_ROOT_PORTS) {
-		printf("The request port(%d) is not configured\n", port - 1);
-		return -1;
-	}
-	status_reg = (uint32_t *)&ctrl->hcor->or_portsc[port - 1];
 	srclen = 0;
 
 	debug("req=%u (%#x), type=%u (%#x), value=%u, index=%u\n",
@@ -630,6 +625,21 @@ ehci_submit_root(struct usb_device *dev, unsigned long pipe, void *buffer,
 
 	typeReq = req->request | req->requesttype << 8;
 
+	switch (typeReq) {
+	case USB_REQ_GET_STATUS | ((USB_RT_PORT | USB_DIR_IN) << 8):
+	case USB_REQ_SET_FEATURE | ((USB_DIR_OUT | USB_RT_PORT) << 8):
+	case USB_REQ_CLEAR_FEATURE | ((USB_DIR_OUT | USB_RT_PORT) << 8):
+		if (!port || port > CONFIG_SYS_USB_EHCI_MAX_ROOT_PORTS) {
+			printf("The request port(%d) is not configured\n", port - 1);
+			return -1;
+		}
+		status_reg = (uint32_t *)&ctrl->hcor->or_portsc[port - 1];
+		break;
+	default:
+		status_reg = NULL;
+		break;
+	}
+
 	switch (typeReq) {
 	case DeviceRequest | USB_REQ_GET_DESCRIPTOR:
 		switch (le16_to_cpu(req->value) >> 8) {