xhci: mediatek: support MTK xHCI host controller

There some vendor quirks for MTK xhci host controller:
1. It defines some extra SW scheduling parameters for HW
  to minimize the scheduling effort for synchronous and
  interrupt endpoints. The parameters are put into reseved
  DWs of slot context and endpoint context.
2. Its IMODI unit for Interrupter Moderation register is
  8 times as much as that defined in xHCI spec.
3. Its TDS in  Normal TRB defines a number of packets that
  remains to be transferred for a TD after processing all
  Max packets in all previous TRBs.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/Kconfig

@@ -41,6 +41,15 @@ config USB_XHCI_PLATFORM
 
 	  If unsure, say N.
 
+config USB_XHCI_MTK
+	tristate "xHCI support for Mediatek MT65xx"
+	select MFD_SYSCON
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	---help---
+	  Say 'Y' to enable the support for the xHCI host controller
+	  found in Mediatek MT65xx SoCs.
+	  If unsure, say N.
+
 config USB_XHCI_MVEBU
 	tristate "xHCI support for Marvell Armada 375/38x"
 	select USB_XHCI_PLATFORM

drivers/usb/host/Makefile

@@ -13,6 +13,9 @@ fhci-$(CONFIG_FHCI_DEBUG) += fhci-dbg.o
 xhci-hcd-y := xhci.o xhci-mem.o
 xhci-hcd-y += xhci-ring.o xhci-hub.o xhci-dbg.o
 xhci-hcd-y += xhci-trace.o
+ifneq ($(CONFIG_USB_XHCI_MTK), )
+	xhci-hcd-y += xhci-mtk-sch.o
+endif
 
 xhci-plat-hcd-y := xhci-plat.o
 ifneq ($(CONFIG_USB_XHCI_MVEBU), )
@@ -64,6 +67,7 @@ obj-$(CONFIG_USB_FHCI_HCD)	+= fhci.o
 obj-$(CONFIG_USB_XHCI_HCD)	+= xhci-hcd.o
 obj-$(CONFIG_USB_XHCI_PCI)	+= xhci-pci.o
 obj-$(CONFIG_USB_XHCI_PLATFORM) += xhci-plat-hcd.o
+obj-$(CONFIG_USB_XHCI_MTK)	+= xhci-mtk.o
 obj-$(CONFIG_USB_SL811_HCD)	+= sl811-hcd.o
 obj-$(CONFIG_USB_SL811_CS)	+= sl811_cs.o
 obj-$(CONFIG_USB_U132_HCD)	+= u132-hcd.o