[PATCH] USB: root hubs can report remote wakeup feature

The patch lets HCDs report the root hub remote wakeup feature to usbcore
through config descriptors, and lets usbcore say whether or not remote
wakeup (of host from sleep, by devices) should be enabled.

Both OHCI and UHCI HCDs have some remote wakeup support already; I'm not
too sure how well it works.  Given (separate) patches, their root hubs
can start to act more like other hubs in this area too.  That'll make
it easier to start using USB suspend mode.

drivers/usb/core/hcd.c

@@ -171,10 +171,10 @@ static const u8 fs_rh_config_descriptor [] = {
 	0x01,       /*  __u8  bNumInterfaces; (1) */
 	0x01,       /*  __u8  bConfigurationValue; */
 	0x00,       /*  __u8  iConfiguration; */
-	0x40,       /*  __u8  bmAttributes; 
-				 Bit 7: Bus-powered,
+	0xc0,       /*  __u8  bmAttributes; 
+				 Bit 7: must be set,
 				     6: Self-powered,
-				     5 Remote-wakwup,
+				     5: Remote wakeup,
 				     4..0: resvd */
 	0x00,       /*  __u8  MaxPower; */
       
@@ -218,10 +218,10 @@ static const u8 hs_rh_config_descriptor [] = {
 	0x01,       /*  __u8  bNumInterfaces; (1) */
 	0x01,       /*  __u8  bConfigurationValue; */
 	0x00,       /*  __u8  iConfiguration; */
-	0x40,       /*  __u8  bmAttributes; 
-				 Bit 7: Bus-powered,
+	0xc0,       /*  __u8  bmAttributes; 
+				 Bit 7: must be set,
 				     6: Self-powered,
-				     5 Remote-wakwup,
+				     5: Remote wakeup,
 				     4..0: resvd */
 	0x00,       /*  __u8  MaxPower; */
       
@@ -324,13 +324,15 @@ static int rh_string (
 /* Root hub control transfers execute synchronously */
 static int rh_call_control (struct usb_hcd *hcd, struct urb *urb)
 {
-	struct usb_ctrlrequest *cmd = (struct usb_ctrlrequest *) urb->setup_packet;
+	struct usb_ctrlrequest *cmd;
  	u16		typeReq, wValue, wIndex, wLength;
 	const u8	*bufp = 0;
 	u8		*ubuf = urb->transfer_buffer;
 	int		len = 0;
+	int		patch_wakeup = 0;
 	unsigned long	flags;
 
+	cmd = (struct usb_ctrlrequest *) urb->setup_packet;
 	typeReq  = (cmd->bRequestType << 8) | cmd->bRequest;
 	wValue   = le16_to_cpu (cmd->wValue);
 	wIndex   = le16_to_cpu (cmd->wIndex);
@@ -347,13 +349,21 @@ static int rh_call_control (struct usb_hcd *hcd, struct urb *urb)
 	/* DEVICE REQUESTS */
 
 	case DeviceRequest | USB_REQ_GET_STATUS:
-		// DEVICE_REMOTE_WAKEUP
-		ubuf [0] = 1; // selfpowered
+		ubuf [0] = (hcd->remote_wakeup << USB_DEVICE_REMOTE_WAKEUP)
+				| (1 << USB_DEVICE_SELF_POWERED);
 		ubuf [1] = 0;
-			/* FALLTHROUGH */
+		break;
 	case DeviceOutRequest | USB_REQ_CLEAR_FEATURE:
+		if (wValue == USB_DEVICE_REMOTE_WAKEUP)
+			hcd->remote_wakeup = 0;
+		else
+			goto error;
+		break;
 	case DeviceOutRequest | USB_REQ_SET_FEATURE:
-		dev_dbg (hcd->self.controller, "no device features yet yet\n");
+		if (hcd->can_wakeup && wValue == USB_DEVICE_REMOTE_WAKEUP)
+			hcd->remote_wakeup = 1;
+		else
+			goto error;
 		break;
 	case DeviceRequest | USB_REQ_GET_CONFIGURATION:
 		ubuf [0] = 1;
@@ -379,6 +389,8 @@ static int rh_call_control (struct usb_hcd *hcd, struct urb *urb)
 				bufp = fs_rh_config_descriptor;
 				len = sizeof fs_rh_config_descriptor;
 			}
+			if (hcd->can_wakeup)
+				patch_wakeup = 1;
 			break;
 		case USB_DT_STRING << 8:
 			urb->actual_length = rh_string (
@@ -444,6 +456,11 @@ static int rh_call_control (struct usb_hcd *hcd, struct urb *urb)
 		urb->actual_length = len;
 		// always USB_DIR_IN, toward host
 		memcpy (ubuf, bufp, len);
+
+		/* report whether RH hardware supports remote wakeup */
+		if (patch_wakeup)
+			((struct usb_config_descriptor *)ubuf)->bmAttributes
+				|= USB_CONFIG_ATT_WAKEUP;
 	}
 
 	/* any errors get returned through the urb completion */

drivers/usb/core/hcd.h

@@ -74,6 +74,8 @@ struct usb_hcd {	/* usb_bus.hcpriv points to this */
 	 */
 	struct hc_driver	*driver;	/* hw-specific hooks */
 	unsigned		saw_irq : 1;
+	unsigned		can_wakeup:1;	/* hw supports wakeup? */
+	unsigned		remote_wakeup:1;/* sw should use wakeup? */
 	int			irq;		/* irq allocated */
 	void			*regs;		/* device memory/io */
 
@@ -344,9 +346,16 @@ extern void usb_deregister_bus (struct usb_bus *);
 extern int usb_register_root_hub (struct usb_device *usb_dev,
 		struct device *parent_dev);
 
-/* for portability to 2.4, hcds should call this */
 static inline int hcd_register_root (struct usb_hcd *hcd)
 {
+	/* hcd->driver->start() reported can_wakeup, probably with
+	 * assistance from board's boot firmware.
+	 * NOTE:  normal devices won't enable wakeup by default.
+	 */
+	if (hcd->can_wakeup)
+		dev_dbg (hcd->self.controller, "supports USB remote wakeup\n");
+	hcd->remote_wakeup = hcd->can_wakeup;
+
 	return usb_register_root_hub (
 		hcd_to_bus (hcd)->root_hub, hcd->self.controller);
 }