xhci: Return a USB 3.0 hub descriptor for USB3 roothub.

Return the correct xHCI roothub descriptor, based on whether the roothub
is marked as USB 3.0 or USB 2.0 in usb_hcd->bcdUSB.  Fill in
DeviceRemovable for the USB 2.0 and USB 3.0 roothub descriptors, using the
Device Removable bit in the port status and control registers.  xHCI is
the first host controller to actually properly set these bits (other hosts
say all devices are removable).

When userspace asks for a USB 2.0-style hub descriptor for the USB 3.0
roothub, stall the endpoint.  This is what real external USB 3.0 hubs do,
and we don't want to return a descriptor that userspace didn't ask for.

The USB core is already fixed to always ask for USB 3.0-style hub
descriptors.  Only usbfs (typically lsusb) will ask for the USB 2.0-style
hub descriptors.  This has already been fixed in usbutils version 0.91,
but the kernel needs to deal with older usbutils versions.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

drivers/usb/host/xhci-hub.c

@@ -28,33 +28,15 @@
 #define	PORT_RWC_BITS	(PORT_CSC | PORT_PEC | PORT_WRC | PORT_OCC | \
 			 PORT_RC | PORT_PLC | PORT_PE)
 
-static void xhci_hub_descriptor(struct usb_hcd *hcd, struct xhci_hcd *xhci,
-		struct usb_hub_descriptor *desc)
+static void xhci_common_hub_descriptor(struct xhci_hcd *xhci,
+		struct usb_hub_descriptor *desc, int ports)
 {
-	int ports;
 	u16 temp;
 
-	if (hcd->speed == HCD_USB3)
-		ports = xhci->num_usb3_ports;
-	else
-		ports = xhci->num_usb2_ports;
-
-	/* FIXME: return a USB 3.0 hub descriptor if this request was for the
-	 * USB3 roothub.
-	 */
-
-	/* USB 3.0 hubs have a different descriptor, but we fake this for now */
-	desc->bDescriptorType = 0x29;
 	desc->bPwrOn2PwrGood = 10;	/* xhci section 5.4.9 says 20ms max */
 	desc->bHubContrCurrent = 0;
 
 	desc->bNbrPorts = ports;
-	temp = 1 + (ports / 8);
-	desc->bDescLength = 7 + 2 * temp;
-
-	memset(&desc->u.hs.DeviceRemovable[0], 0, temp);
-	memset(&desc->u.hs.DeviceRemovable[temp], 0xff, temp);
-
 	/* Ugh, these should be #defines, FIXME */
 	/* Using table 11-13 in USB 2.0 spec. */
 	temp = 0;
@@ -71,6 +53,102 @@ static void xhci_hub_descriptor(struct usb_hcd *hcd, struct xhci_hcd *xhci,
 	desc->wHubCharacteristics = (__force __u16) cpu_to_le16(temp);
 }
 
+/* Fill in the USB 2.0 roothub descriptor */
+static void xhci_usb2_hub_descriptor(struct usb_hcd *hcd, struct xhci_hcd *xhci,
+		struct usb_hub_descriptor *desc)
+{
+	int ports;
+	u16 temp;
+	__u8 port_removable[(USB_MAXCHILDREN + 1 + 7) / 8];
+	u32 portsc;
+	unsigned int i;
+
+	ports = xhci->num_usb2_ports;
+
+	xhci_common_hub_descriptor(xhci, desc, ports);
+	desc->bDescriptorType = 0x29;
+	temp = 1 + (ports / 8);
+	desc->bDescLength = 7 + 2 * temp;
+
+	/* The Device Removable bits are reported on a byte granularity.
+	 * If the port doesn't exist within that byte, the bit is set to 0.
+	 */
+	memset(port_removable, 0, sizeof(port_removable));
+	for (i = 0; i < ports; i++) {
+		portsc = xhci_readl(xhci, xhci->usb3_ports[i]);
+		/* If a device is removable, PORTSC reports a 0, same as in the
+		 * hub descriptor DeviceRemovable bits.
+		 */
+		if (portsc & PORT_DEV_REMOVE)
+			/* This math is hairy because bit 0 of DeviceRemovable
+			 * is reserved, and bit 1 is for port 1, etc.
+			 */
+			port_removable[(i + 1) / 8] |= 1 << ((i + 1) % 8);
+	}
+
+	/* ch11.h defines a hub descriptor that has room for USB_MAXCHILDREN
+	 * ports on it.  The USB 2.0 specification says that there are two
+	 * variable length fields at the end of the hub descriptor:
+	 * DeviceRemovable and PortPwrCtrlMask.  But since we can have less than
+	 * USB_MAXCHILDREN ports, we may need to use the DeviceRemovable array
+	 * to set PortPwrCtrlMask bits.  PortPwrCtrlMask must always be set to
+	 * 0xFF, so we initialize the both arrays (DeviceRemovable and
+	 * PortPwrCtrlMask) to 0xFF.  Then we set the DeviceRemovable for each
+	 * set of ports that actually exist.
+	 */
+	memset(desc->u.hs.DeviceRemovable, 0xff,
+			sizeof(desc->u.hs.DeviceRemovable));
+	memset(desc->u.hs.PortPwrCtrlMask, 0xff,
+			sizeof(desc->u.hs.PortPwrCtrlMask));
+
+	for (i = 0; i < (ports + 1 + 7) / 8; i++)
+		memset(&desc->u.hs.DeviceRemovable[i], port_removable[i],
+				sizeof(__u8));
+}
+
+/* Fill in the USB 3.0 roothub descriptor */
+static void xhci_usb3_hub_descriptor(struct usb_hcd *hcd, struct xhci_hcd *xhci,
+		struct usb_hub_descriptor *desc)
+{
+	int ports;
+	u16 port_removable;
+	u32 portsc;
+	unsigned int i;
+
+	ports = xhci->num_usb3_ports;
+	xhci_common_hub_descriptor(xhci, desc, ports);
+	desc->bDescriptorType = 0x2a;
+	desc->bDescLength = 12;
+
+	/* header decode latency should be zero for roothubs,
+	 * see section 4.23.5.2.
+	 */
+	desc->u.ss.bHubHdrDecLat = 0;
+	desc->u.ss.wHubDelay = 0;
+
+	port_removable = 0;
+	/* bit 0 is reserved, bit 1 is for port 1, etc. */
+	for (i = 0; i < ports; i++) {
+		portsc = xhci_readl(xhci, xhci->usb3_ports[i]);
+		if (portsc & PORT_DEV_REMOVE)
+			port_removable |= 1 << (i + 1);
+	}
+	memset(&desc->u.ss.DeviceRemovable,
+			(__force __u16) cpu_to_le16(port_removable),
+			sizeof(__u16));
+}
+
+static void xhci_hub_descriptor(struct usb_hcd *hcd, struct xhci_hcd *xhci,
+		struct usb_hub_descriptor *desc)
+{
+
+	if (hcd->speed == HCD_USB3)
+		xhci_usb3_hub_descriptor(hcd, xhci, desc);
+	else
+		xhci_usb2_hub_descriptor(hcd, xhci, desc);
+
+}
+
 static unsigned int xhci_port_speed(unsigned int port_status)
 {
 	if (DEV_LOWSPEED(port_status))
@@ -320,6 +398,17 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 		memset(buf, 0, 4);
 		break;
 	case GetHubDescriptor:
+		/* Check to make sure userspace is asking for the USB 3.0 hub
+		 * descriptor for the USB 3.0 roothub.  If not, we stall the
+		 * endpoint, like external hubs do.
+		 */
+		if (hcd->speed == HCD_USB3 &&
+				(wLength < USB_DT_SS_HUB_SIZE ||
+				 wValue != (USB_DT_SS_HUB << 8))) {
+			xhci_dbg(xhci, "Wrong hub descriptor type for "
+					"USB 3.0 roothub.\n");
+			goto error;
+		}
 		xhci_hub_descriptor(hcd, xhci,
 				(struct usb_hub_descriptor *) buf);
 		break;
@@ -331,6 +420,9 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 		temp = xhci_readl(xhci, port_array[wIndex]);
 		xhci_dbg(xhci, "get port status, actual port %d status  = 0x%x\n", wIndex, temp);
 
+		/* FIXME - should we return a port status value like the USB
+		 * 3.0 external hubs do?
+		 */
 		/* wPortChange bits */
 		if (temp & PORT_CSC)
 			status |= USB_PORT_STAT_C_CONNECTION << 16;
@@ -401,6 +493,7 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 		wIndex--;
 		temp = xhci_readl(xhci, port_array[wIndex]);
 		temp = xhci_port_state_to_neutral(temp);
+		/* FIXME: What new port features do we need to support? */
 		switch (wValue) {
 		case USB_PORT_FEAT_SUSPEND:
 			temp = xhci_readl(xhci, port_array[wIndex]);
@@ -469,6 +562,7 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 			goto error;
 		wIndex--;
 		temp = xhci_readl(xhci, port_array[wIndex]);
+		/* FIXME: What new port features do we need to support? */
 		temp = xhci_port_state_to_neutral(temp);
 		switch (wValue) {
 		case USB_PORT_FEAT_SUSPEND: