dwc3: Handle optional clocks

Usually dwc3 needs a glue node that contain the SoC specific clocks/resets.
For some reason the RK3328 DTS doesn't have this glue node and the clocks
are specified in the dwc3 node directly.
The bindings says that it is allowed but doesn't specified some strict names
for them.
Add a specific case for RK3328 based on the compatible string.

Reviewed by:	andrew
Differential Revision:	https://reviews.freebsd.org/D37392
Sponsored by:	Beckhoff Automation GmbH & Co. KG

sys/dev/usb/controller/dwc3.c

@@ -86,6 +86,11 @@ struct snps_dwc3_softc {
 	bus_space_tag_t		bst;
 	bus_space_handle_t	bsh;
 	uint32_t		snpsid;
+#ifdef FDT
+	clk_t			clk_ref;
+	clk_t			clk_suspend;
+	clk_t			clk_bus;
+#endif
 };
 
 #define	DWC3_WRITE(_sc, _off, _val)		\
@@ -394,9 +399,32 @@ snps_dwc3_common_attach(device_t dev, bool is_fdt)
 	if (!is_fdt)
 		goto skip_phys;
 
-	/* Get the phys */
 	node = ofw_bus_get_node(dev);
 
+	/* Get the clocks if any */
+	if (ofw_bus_is_compatible(dev, "rockchip,rk3328-dwc3") == 1) {
+		if (clk_get_by_ofw_name(dev, node, "ref_clk", &sc->clk_ref) != 0)
+			device_printf(dev, "Cannot get ref_clk\n");
+		if (clk_get_by_ofw_name(dev, node, "suspend_clk", &sc->clk_suspend) != 0)
+			device_printf(dev, "Cannot get suspend_clk\n");
+		if (clk_get_by_ofw_name(dev, node, "bus_clk", &sc->clk_bus) != 0)
+			device_printf(dev, "Cannot get bus_clk\n");
+	}
+
+	if (sc->clk_ref != NULL) {
+		if (clk_enable(sc->clk_ref) != 0)
+			device_printf(dev, "Cannot enable ref_clk\n");
+	}
+	if (sc->clk_suspend != NULL) {
+		if (clk_enable(sc->clk_suspend) != 0)
+			device_printf(dev, "Cannot enable suspend_clk\n");
+	}
+	if (sc->clk_bus != NULL) {
+		if (clk_enable(sc->clk_bus) != 0)
+			device_printf(dev, "Cannot enable bus_clk\n");
+	}
+
+	/* Get the phys */
 	usb2_phy = usb3_phy = NULL;
 	error = phy_get_by_ofw_name(dev, node, "usb2-phy", &usb2_phy);
 	if (error == 0 && usb2_phy != NULL)
@@ -427,6 +455,16 @@ snps_dwc3_common_attach(device_t dev, bool is_fdt)
 	snsp_dwc3_dump_regs(sc, "Post XHCI init");
 #endif
 
+#ifdef FDT
+	if (error) {
+		if (sc->clk_ref != NULL)
+			clk_disable(sc->clk_ref);
+		if (sc->clk_suspend != NULL)
+			clk_disable(sc->clk_suspend);
+		if (sc->clk_bus != NULL)
+			clk_disable(sc->clk_bus);
+	}
+#endif
 	return (error);
 }