usb: dwc2: add amcc,dwc-otg support

This patch adds support for the "amcc,usb-otg" device
which is found in the PowerPC Canyonlands' dts.

The device definition was added by:

commit c89b3458d8 ("powerpc/44x: Add USB DWC DTS entry to Canyonlands
board")

but without any driver support as the dwc2 driver wasn't available at
that time.

Note: The system can't use the generic "snps,dwc2" compatible
because of the special ahbcfg configuration. The default
GAHBCFG_HBSTLEN_INCR4 of snps,dwc2 can cause a system hang
when the USB and SATA is used concurrently.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

Documentation/devicetree/bindings/usb/dwc2.txt

@@ -12,6 +12,7 @@ Required properties:
   - "lantiq,xrx200-usb": The DWC2 USB controller instance in Lantiq XRX SoCs;
   - "amlogic,meson8b-usb": The DWC2 USB controller instance in Amlogic Meson8b SoCs;
   - "amlogic,meson-gxbb-usb": The DWC2 USB controller instance in Amlogic S905 SoCs;
+  - "amcc,dwc-otg": The DWC2 USB controller instance in AMCC Canyonlands 460EX SoCs;
   - snps,dwc2: A generic DWC2 USB controller with default parameters.
 - reg : Should contain 1 register range (address and length)
 - interrupts : Should contain 1 interrupt

drivers/usb/dwc2/params.c

@@ -239,6 +239,7 @@ const struct of_device_id dwc2_of_match_table[] = {
 	{ .compatible = "samsung,s3c6400-hsotg", .data = NULL},
 	{ .compatible = "amlogic,meson8b-usb", .data = &params_amlogic },
 	{ .compatible = "amlogic,meson-gxbb-usb", .data = &params_amlogic },
+	{ .compatible = "amcc,dwc-otg", .data = NULL },
 	{},
 };
 MODULE_DEVICE_TABLE(of, dwc2_of_match_table);