Add USB Audio 1.0 support

Original commit credit to Amaury Pouly, Moshe Piekarski
Pushed across the finish line by Dana Conrad

To enable, see setting under General Settings --> System --> USB-DAC.
On devices with few endpoints, this may not work while HID and/or
mass storage is enabled.

Adds new dedicated mixer channel.

setting usb-dac can have values:
- never (0)
- always (1)
- while_charge_only (2)
- while_mass_storage (3)

Relevant devices are DWC2 and ARC usb controller devices. That being:
x1000 Native targets (m3k, erosqnative, q1, others...?),
sansac200, creativezenxfi2, vibe500, ipodmini2g,
ipod4g, creativezenxfi, creativezenxfi3, sansaview, ipodcolor,
creativezenxfistyle, samsungypz5, sansafuzeplus, iriverh10_5gb,
tatungtpj1022, gigabeats, faketarget, samsungyh820, gogearhdd1630, samsungyh925, ipodmini1g, ipodvideo, creativezenmozaic, sonynwze370, creativezen, gogearsa9200, gogearhdd6330, sonynwze360, sansae200, mrobe100, iriverh10, creativezenv, ipodnano1g, samsungyh920

USB Driver-wise, it should be noted that this patch requires some
slight changes:
- proper blocking on control OUT transfers, to make sure the data is
  received *before* using it, the usb_core should probably use that too
- drivers can now support interface alternate settings
- drivers can be notified of completion by a new fast handler, which
  is called directly from the driver; this is is necessary for
  isochronous transfers because going through the usb queue is way too
  slow

Designware changes:

- enable for USBOTG_DESIGNWARE
- set maxpacketsize to 1023 for ISO endpoints

Change-Id: I570871884a4e4820b4312b203b07701f06ecacc6

firmware/drivers/usb-designware.c

@@ -231,7 +231,7 @@ static void usb_dw_set_stall(int epnum, enum usb_dw_epdir epdir, int stall)
     else
     {
         DWC_EPCTL(epnum, epdir) &= ~STALL;
-        DWC_EPCTL(epnum, epdir) |= SD0PID;
+        DWC_EPCTL(epnum, epdir) |= SETD0PIDEF;
     }
 }
 
@@ -668,7 +668,7 @@ static void usb_dw_unconfigure_ep(int epnum, enum usb_dw_epdir epdir)
 static int usb_dw_configure_ep(int epnum,
                 enum usb_dw_epdir epdir, int type, int maxpktsize)
 {
-    uint32_t epctl = SD0PID|EPTYP(type)|USBAEP|maxpktsize;
+    uint32_t epctl = SETD0PIDEF|EPTYP(type)|USBAEP|maxpktsize;
 
     if (epdir == USB_DW_EPDIR_IN)
     {
@@ -1259,7 +1259,7 @@ static void usb_dw_irq(void)
                          * FIFO and raises StatusRecvd | XferCompl.
                          *
                          * We do not need or want this -- we've already handled
-                         * the data phase by this point -- but EP0 is stoppped
+                         * the data phase by this point -- but EP0 is stopped
                          * as a side effect of XferCompl, so we need to restart
                          * it to keep receiving packets. */
                         usb_dw_ep0_recv();
@@ -1528,7 +1528,7 @@ void usb_drv_cancel_all_transfers()
                 {
                     //usb_dw_flush_endpoint(ep, dir);
                     usb_dw_abort_endpoint(ep, dir);
-                    DWC_EPCTL(ep, dir) |= SD0PID;
+                    DWC_EPCTL(ep, dir) |= SETD0PIDEF;
                 }
     usb_dw_target_enable_irq();
 }
@@ -1606,8 +1606,15 @@ int usb_drv_request_endpoint(int type, int dir)
             struct usb_dw_ep* dw_ep = usb_dw_get_ep(ep, epdir);
             if (!dw_ep->active)
             {
+                int maxpktsize = 64;
+                if (type == EPTYP_ISOCHRONOUS){
+                    maxpktsize = 1023;
+                } else {
+                    maxpktsize = usb_drv_port_speed() ? 512 : 64;
+                }
+
                 if (usb_dw_configure_ep(ep, epdir, type,
-                                usb_drv_port_speed() ? 512 : 64) >= 0)
+                                maxpktsize) >= 0)
                 {
                     dw_ep->active = true;
                     request_ep = ep | dir;
@@ -1679,3 +1686,11 @@ void usb_drv_control_response(enum usb_control_response resp,
     usb_dw_control_response(resp, data, length);
     usb_dw_target_enable_irq();
 }
+
+int usb_drv_get_frame_number()
+{
+    // SOFFN is 14 bits, the least significant 3 appear to be some sort of microframe count.
+    // The USB spec says a frame number is 11 bits. This way we get 1 frame per millisecond,
+    // just like we're supposed to!
+    return (DWC_DSTS >> 11) & 0x7FF;
+}