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>

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 @@ struct acc_dev {
 	/* 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 @@ static long acc_ioctl(struct file *fp, unsigned code, unsigned long value)
 		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 @@ static int acc_ctrlrequest(struct usb_composite_dev *cdev,
 			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 @@ static int acc_ctrlrequest(struct usb_composite_dev *cdev,
 			memset(dev->uri, 0, sizeof(dev->uri));
 			memset(dev->serial, 0, sizeof(dev->serial));
 			dev->start_requested = 0;
+			dev->audio_mode = 0;
 		}
 	}
 

include/linux/usb/f_accessory.h

@@ -36,13 +36,15 @@
 #define ACCESSORY_STRING_URI            4
 #define ACCESSORY_STRING_SERIAL         5
 
-/* Control request for retrieving device's protocol version (currently 1)
+/* Control request for retrieving device's protocol version
  *
  *	requestType:    USB_DIR_IN | USB_TYPE_VENDOR
  *	request:        ACCESSORY_GET_PROTOCOL
  *	value:          0
  *	index:          0
  *	data            version number (16 bits little endian)
+ *                     1 for original accessory support
+ *                     2 adds device to host audio support
  */
 #define ACCESSORY_GET_PROTOCOL  51
 
@@ -70,6 +72,17 @@
  */
 #define ACCESSORY_START         53
 
+/* Control request for setting the audio mode.
+ *
+ *	requestType:	USB_DIR_OUT | USB_TYPE_VENDOR
+ *	request:        ACCESSORY_SET_AUDIO_MODE
+ *	value:          0 - no audio
+ *                     1 - device to host, 44100 16-bit stereo PCM
+ *	index:          0
+ *	data            none
+ */
+#define ACCESSORY_SET_AUDIO_MODE         58
+
 /* ioctls for retrieving strings set by the host */
 #define ACCESSORY_GET_STRING_MANUFACTURER   _IOW('M', 1, char[256])
 #define ACCESSORY_GET_STRING_MODEL          _IOW('M', 2, char[256])
@@ -79,5 +92,7 @@
 #define ACCESSORY_GET_STRING_SERIAL         _IOW('M', 6, char[256])
 /* returns 1 if there is a start request pending */
 #define ACCESSORY_IS_START_REQUESTED        _IO('M', 7)
+/* returns audio mode (set via the ACCESSORY_SET_AUDIO_MODE control request) */
+#define ACCESSORY_GET_AUDIO_MODE            _IO('M', 8)
 
 #endif /* __LINUX_USB_F_ACCESSORY_H */