usb: host: add Kconfig option for EHSET

commit 9841f37a1c ("usb: ehci: Add support for SINGLE_STEP_SET_FEATURE
test of EHSET") added additional code to the EHCI hub driver but it is
anticipated to only have a limited audience (e.g. embedded silicon
vendors and integrators). Avoid subjecting all EHCI (and in the future
maybe xHCI/OHCI, etc.) HCD users to code bloat by conditionally
compiling the EHSET-specific additions with a new Kconfig option,
CONFIG_USB_HCD_TEST_MODE.

Signed-off-by: Jack Pham <jackp@codeaurora.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/Kconfig

@@ -699,3 +699,20 @@ config USB_HCD_SSB
 	  for ehci and ohci.
 
 	  If unsure, say N.
+
+config USB_HCD_TEST_MODE
+	bool "HCD test mode support"
+	---help---
+	  Say 'Y' to enable additional software test modes that may be
+	  supported by the host controller drivers.
+
+	  One such test mode is the Embedded High-speed Host Electrical Test
+	  (EHSET) for EHCI host controller hardware, specifically the "Single
+	  Step Set Feature" test.  Typically this will be enabled for On-the-Go
+	  or embedded hosts that need to undergo USB-IF compliance testing with
+	  the aid of special testing hardware.  In the future, this may expand
+	  to include other tests that require support from a HCD driver.
+
+	  This option is of interest only to developers who need to validate
+	  their USB hardware designs.  It is not needed for normal use.  If
+	  unsure, say N.

drivers/usb/host/ehci-hub.c

@@ -712,6 +712,8 @@ ehci_hub_descriptor (
 }
 
 /*-------------------------------------------------------------------------*/
+#ifdef CONFIG_USB_HCD_TEST_MODE
+
 #define EHSET_TEST_SINGLE_STEP_SET_FEATURE 0x06
 
 static void usb_ehset_completion(struct urb *urb)
@@ -847,6 +849,7 @@ cleanup:
 	kfree(buf);
 	return retval;
 }
+#endif /* CONFIG_USB_HCD_TEST_MODE */
 /*-------------------------------------------------------------------------*/
 
 static int ehci_hub_control (
@@ -1222,13 +1225,16 @@ static int ehci_hub_control (
 		 * about the EHCI-specific stuff.
 		 */
 		case USB_PORT_FEAT_TEST:
+#ifdef CONFIG_USB_HCD_TEST_MODE
 			if (selector == EHSET_TEST_SINGLE_STEP_SET_FEATURE) {
 				spin_unlock_irqrestore(&ehci->lock, flags);
 				retval = ehset_single_step_set_feature(hcd,
 									wIndex);
 				spin_lock_irqsave(&ehci->lock, flags);
 				break;
-			} else if (!selector || selector > 5)
+			}
+#endif
+			if (!selector || selector > 5)
 				goto error;
 			spin_unlock_irqrestore(&ehci->lock, flags);
 			ehci_quiesce(ehci);

drivers/usb/host/ehci-q.c

@@ -1139,6 +1139,7 @@ submit_async (
 }
 
 /*-------------------------------------------------------------------------*/
+#ifdef CONFIG_USB_HCD_TEST_MODE
 /*
  * This function creates the qtds and submits them for the
  * SINGLE_STEP_SET_FEATURE Test.
@@ -1238,6 +1239,7 @@ cleanup:
 	qtd_list_free(ehci, urb, head);
 	return -1;
 }
+#endif /* CONFIG_USB_HCD_TEST_MODE */
 
 /*-------------------------------------------------------------------------*/