usb: gadget: f_hid: {GET,SET} PROTOCOL Support

The current f_hid driver doesn't handle GET_PROCOTOL and
SET_PROCOTOL requests, which are required to operate HID
gadgets in BOOT mode. This patch implements this feature for
devices that have the same implementation for REPORT and BOOT mode
so that these devices are recognized by older BIOSes.
Signed-off-by: Abdulhadi Mohamed <abdulahhadi2@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/function/f_hid.c

@@ -44,6 +44,7 @@ struct f_hidg {
 	/* configuration */
 	unsigned char			bInterfaceSubClass;
 	unsigned char			bInterfaceProtocol;
+	unsigned char			protocol;
 	unsigned short			report_desc_length;
 	char				*report_desc;
 	unsigned short			report_length;
@@ -527,7 +528,9 @@ static int hidg_setup(struct usb_function *f,
 	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8
 		  | HID_REQ_GET_PROTOCOL):
 		VDBG(cdev, "get_protocol\n");
-		goto stall;
+		length = min_t(unsigned int, length, 1);
+		((u8 *) req->buf)[0] = hidg->protocol;
+		goto respond;
 		break;
 
 	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8
@@ -539,6 +542,17 @@ static int hidg_setup(struct usb_function *f,
 	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8
 		  | HID_REQ_SET_PROTOCOL):
 		VDBG(cdev, "set_protocol\n");
+		if (value > HID_REPORT_PROTOCOL)
+			goto stall;
+		length = 0;
+		/*
+		 * We assume that programs implementing the Boot protocol
+		 * are also compatible with the Report Protocol
+		 */
+		if (hidg->bInterfaceSubClass == USB_INTERFACE_SUBCLASS_BOOT) {
+			hidg->protocol = value;
+			goto respond;
+		}
 		goto stall;
 		break;
 
@@ -768,6 +782,7 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f)
 	/* set descriptor dynamic values */
 	hidg_interface_desc.bInterfaceSubClass = hidg->bInterfaceSubClass;
 	hidg_interface_desc.bInterfaceProtocol = hidg->bInterfaceProtocol;
+	hidg->protocol = HID_REPORT_PROTOCOL;
 	hidg_ss_in_ep_desc.wMaxPacketSize = cpu_to_le16(hidg->report_length);
 	hidg_ss_in_comp_desc.wBytesPerInterval =
 				cpu_to_le16(hidg->report_length);

include/linux/hid.h

@@ -362,6 +362,12 @@ struct hid_item {
 #define HID_GROUP_WACOM				0x0101
 #define HID_GROUP_LOGITECH_DJ_DEVICE		0x0102
 
+/*
+ * HID protocol status
+ */
+#define HID_REPORT_PROTOCOL	1
+#define HID_BOOT_PROTOCOL	0
+
 /*
  * This is the global environment of the parser. This information is
  * persistent for main-items. The global environment can be saved and