ANDROID: USB: gadget: Add ACCESSORY_SET_AUDIO_MODE control request and ioctl

The control request will be used by the host to enable/disable USB audio
and the ioctl will be used by userspace to read the audio mode

Change-Id: I81c38611b588451e80eacdccc417ca6e11c60cab
Signed-off-by: Mike Lockwood <lockwood@google.com>
diff --git a/drivers/usb/gadget/f_accessory.c b/drivers/usb/gadget/f_accessory.c
index 04ceb09..07c29d9 100644
--- a/drivers/usb/gadget/f_accessory.c
+++ b/drivers/usb/gadget/f_accessory.c
@@ -40,7 +40,7 @@
 #define BULK_BUFFER_SIZE    16384
 #define ACC_STRING_SIZE     256
 
-#define PROTOCOL_VERSION    1
+#define PROTOCOL_VERSION    2
 
 /* String IDs */
 #define INTERFACE_STRING_INDEX	0
@@ -78,6 +78,8 @@
 	/* set to 1 if we have a pending start request */
 	int start_requested;
 
+	int audio_mode;
+
 	/* synchronize access to our device file */
 	atomic_t open_excl;
 
@@ -510,6 +512,8 @@
 		break;
 	case ACCESSORY_IS_START_REQUESTED:
 		return dev->start_requested;
+	case ACCESSORY_GET_AUDIO_MODE:
+		return dev->audio_mode;
 	}
 	if (!src)
 		return -EINVAL;
@@ -586,6 +590,10 @@
 			cdev->gadget->ep0->driver_data = dev;
 			cdev->req->complete = acc_complete_set_string;
 			value = w_length;
+		} else if (b_request == ACCESSORY_SET_AUDIO_MODE &&
+				w_index == 0 && w_length == 0) {
+			dev->audio_mode = w_value;
+			value = 0;
 		}
 	} else if (b_requestType == (USB_DIR_IN | USB_TYPE_VENDOR)) {
 		if (b_request == ACCESSORY_GET_PROTOCOL) {
@@ -600,6 +608,7 @@
 			memset(dev->uri, 0, sizeof(dev->uri));
 			memset(dev->serial, 0, sizeof(dev->serial));
 			dev->start_requested = 0;
+			dev->audio_mode = 0;
 		}
 	}