mach-meson: g12a: add DWC2 peripheral mode support

Adds support for Amlogic G12A USB Device mode.

The DWC2 Controller behind the Glue can be connected to an OTG
capable PHY. The Glue setups the PHY mode.

This patch implements Device mode support by adding a board_usb_init/cleanup
setting up the DWC2 controller and switch the OTG capable port to Device
before starting the DWC2 controller in Device mode.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>

arch/arm/include/asm/arch-meson/usb.h

@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2019 BayLibre, SAS
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ */
+
+#ifndef __MESON_USB_H__
+#define __MESON_USB_H__
+
+int dwc3_meson_g12a_force_mode(struct udevice *dev, enum usb_dr_mode mode);
+
+#endif /* __MESON_USB_H__ */

arch/arm/mach-meson/board-g12a.c

@@ -12,7 +12,12 @@
 #include <asm/io.h>
 #include <asm/armv8/mmu.h>
 #include <linux/sizes.h>
+#include <usb.h>
+#include <linux/usb/otg.h>
+#include <asm/arch/usb.h>
+#include <usb/dwc2_udc.h>
 #include <phy.h>
+#include <clk.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -148,3 +153,124 @@ void meson_eth_init(phy_interface_t mode, unsigned int flags)
 	/* Enable power gate */
 	clrbits_le32(G12A_MEM_PD_REG_0, G12A_MEM_PD_REG_0_ETH_MASK);
 }
+
+#if CONFIG_IS_ENABLED(USB_DWC3_MESON_G12A) && \
+	CONFIG_IS_ENABLED(USB_GADGET_DWC2_OTG)
+static struct dwc2_plat_otg_data meson_g12a_dwc2_data;
+
+int board_usb_init(int index, enum usb_init_type init)
+{
+	struct fdtdec_phandle_args args;
+	const void *blob = gd->fdt_blob;
+	int node, dwc2_node;
+	struct udevice *dev, *clk_dev;
+	struct clk clk;
+	int ret;
+
+	/* find the usb glue node */
+	node = fdt_node_offset_by_compatible(blob, -1,
+					     "amlogic,meson-g12a-usb-ctrl");
+	if (node < 0) {
+		debug("Not found usb-control node\n");
+		return -ENODEV;
+	}
+
+	if (!fdtdec_get_is_enabled(blob, node)) {
+		debug("usb is disabled in the device tree\n");
+		return -ENODEV;
+	}
+
+	ret = uclass_get_device_by_of_offset(UCLASS_SIMPLE_BUS, node, &dev);
+	if (ret) {
+		debug("Not found usb-control device\n");
+		return ret;
+	}
+
+	/* find the dwc2 node */
+	dwc2_node = fdt_node_offset_by_compatible(blob, node,
+						  "amlogic,meson-g12a-usb");
+	if (dwc2_node < 0) {
+		debug("Not found dwc2 node\n");
+		return -ENODEV;
+	}
+
+	if (!fdtdec_get_is_enabled(blob, dwc2_node)) {
+		debug("dwc2 is disabled in the device tree\n");
+		return -ENODEV;
+	}
+
+	meson_g12a_dwc2_data.regs_otg = fdtdec_get_addr(blob, dwc2_node, "reg");
+	if (meson_g12a_dwc2_data.regs_otg == FDT_ADDR_T_NONE) {
+		debug("usbotg: can't get base address\n");
+		return -ENODATA;
+	}
+
+	/* Enable clock */
+	ret = fdtdec_parse_phandle_with_args(blob, dwc2_node, "clocks",
+					     "#clock-cells", 0, 0, &args);
+	if (ret) {
+		debug("usbotg has no clocks defined in the device tree\n");
+		return ret;
+	}
+
+	ret = uclass_get_device_by_of_offset(UCLASS_CLK, args.node, &clk_dev);
+	if (ret)
+		return ret;
+
+	if (args.args_count != 1) {
+		debug("Can't find clock ID in the device tree\n");
+		return -ENODATA;
+	}
+
+	clk.dev = clk_dev;
+	clk.id = args.args[0];
+
+	ret = clk_enable(&clk);
+	if (ret) {
+		debug("Failed to enable usbotg clock\n");
+		return ret;
+	}
+
+	meson_g12a_dwc2_data.rx_fifo_sz = fdtdec_get_int(blob, dwc2_node,
+						     "g-rx-fifo-size", 0);
+	meson_g12a_dwc2_data.np_tx_fifo_sz = fdtdec_get_int(blob, dwc2_node,
+							"g-np-tx-fifo-size", 0);
+	meson_g12a_dwc2_data.tx_fifo_sz = fdtdec_get_int(blob, dwc2_node,
+						     "g-tx-fifo-size", 0);
+
+	/* Switch to peripheral mode */
+	ret = dwc3_meson_g12a_force_mode(dev, USB_DR_MODE_PERIPHERAL);
+	if (ret)
+		return ret;
+
+	return dwc2_udc_probe(&meson_g12a_dwc2_data);
+}
+
+int board_usb_cleanup(int index, enum usb_init_type init)
+{
+	const void *blob = gd->fdt_blob;
+	struct udevice *dev;
+	int node;
+	int ret;
+
+	/* find the usb glue node */
+	node = fdt_node_offset_by_compatible(blob, -1,
+					     "amlogic,meson-g12a-usb-ctrl");
+	if (node < 0)
+		return -ENODEV;
+
+	if (!fdtdec_get_is_enabled(blob, node))
+		return -ENODEV;
+
+	ret = uclass_get_device_by_of_offset(UCLASS_SIMPLE_BUS, node, &dev);
+	if (ret)
+		return ret;
+
+	/* Switch to OTG mode */
+	ret = dwc3_meson_g12a_force_mode(dev, USB_DR_MODE_HOST);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+#endif