[PATCH v1 2/2] usb: dwc3: Add Renesas R-Car Gen5 DWC3 xHCI USB controller glue

From: Thanh Quan <[email protected]>

The Renesas R-Car Gen5 SoC contains multiple instances of DWC3 USB
controller with glue logic wrapper around them. Add driver for the
glue logic around the DWC3 USB controller core.

Signed-off-by: Thanh Quan <[email protected]>
Signed-off-by: Marek Vasut <[email protected]>
---
Cc: Conor Dooley <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Krzysztof Kozlowski <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Thinh Nguyen <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
 drivers/usb/dwc3/Kconfig          |  10 ++
 drivers/usb/dwc3/Makefile         |   1 +
 drivers/usb/dwc3/dwc3-rcar-gen5.c | 150 ++++++++++++++++++++++++++++++
 3 files changed, 161 insertions(+)
 create mode 100644 drivers/usb/dwc3/dwc3-rcar-gen5.c

diff --git a/drivers/usb/dwc3/Kconfig b/drivers/usb/dwc3/Kconfig
index 18169727a413e..7d8ee192b1241 100644
--- a/drivers/usb/dwc3/Kconfig
+++ b/drivers/usb/dwc3/Kconfig
@@ -234,4 +234,14 @@ config USB_DWC3_GOOGLE
 	  To compile this driver as a module, choose M here: the
 	  module will be called dwc3-google.ko.
 
+config USB_DWC3_RCAR_GEN5
+	tristate "Renesas R-Car Gen5 DWC3 Platform Driver"
+	depends on ARCH_RENESAS || COMPILE_TEST
+	default USB_DWC3
+	help
+	  Support the DesignWare Core USB3 IP found on Renesas R-Car Gen5
+	  SoC. This driver provides the glue layer for the USB controller
+	  on Renesas R-Car Gen5 platform.
+	  Say 'Y' or 'M' if you have such device.
+
 endif
diff --git a/drivers/usb/dwc3/Makefile b/drivers/usb/dwc3/Makefile
index f37971197203e..99bbd147f0b5f 100644
--- a/drivers/usb/dwc3/Makefile
+++ b/drivers/usb/dwc3/Makefile
@@ -61,3 +61,4 @@ obj-$(CONFIG_USB_DWC3_OCTEON)		+= dwc3-octeon.o
 obj-$(CONFIG_USB_DWC3_RTK)		+= dwc3-rtk.o
 obj-$(CONFIG_USB_DWC3_GENERIC_PLAT)	+= dwc3-generic-plat.o
 obj-$(CONFIG_USB_DWC3_GOOGLE)		+= dwc3-google.o
+obj-$(CONFIG_USB_DWC3_RCAR_GEN5)	+= dwc3-rcar-gen5.o
diff --git a/drivers/usb/dwc3/dwc3-rcar-gen5.c b/drivers/usb/dwc3/dwc3-rcar-gen5.c
new file mode 100644
index 0000000000000..344d0851559f5
--- /dev/null
+++ b/drivers/usb/dwc3/dwc3-rcar-gen5.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Renesas USB device driver with DWC3 integration
+ *
+ * Copyright (C) 2025-2026 Renesas Electronics Corporation
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+
+struct dwc3_rcar_gen5_priv {
+	void __iomem		*base;
+	struct clk		*clk;
+	bool			use_usb3_flow;
+};
+
+static int dwc3_rcar_gen5_init(struct dwc3_rcar_gen5_priv *priv)
+{
+	/*
+	 * The datasheet describes initialization procedure without full
+	 * information about the registers. Therefore, the source code is
+	 * based on the bare metal code shared by the board team.
+	 */
+	writew(0x211, priv->base + 0x26);
+
+	/* USB3 does not need additional register programming. */
+	if (priv->use_usb3_flow)
+		return 0;
+
+	writew(0x11, priv->base + 0x81c);
+	writew(0x0, priv->base + 0x81a);
+	writew(0x1, priv->base + 0x802);
+
+	usleep_range(10000, 20000);
+
+	writew(0x0, priv->base + 0x802);
+	writew(0x1, priv->base + 0x2a);
+	writew(0x1, priv->base + 0x81a);
+
+	usleep_range(10000, 20000);
+
+	return 0;
+}
+
+static int dwc3_rcar_gen5_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *subnode;
+	struct reset_control *reset;
+	const char *maximum_speed;
+	struct dwc3_rcar_gen5_priv *priv;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return dev_err_probe(dev, PTR_ERR(priv->base), "Failed to map registers\n");
+
+	reset = devm_reset_control_get(dev, NULL);
+	if (IS_ERR(reset))
+		return dev_err_probe(dev, PTR_ERR(reset), "Failed to get reset control\n");
+
+	priv->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(priv->clk))
+		return dev_err_probe(dev, PTR_ERR(priv->clk), "Failed to get clock control\n");
+
+	subnode = of_get_compatible_child(dev->of_node, "synopsys,dwc3");
+	if (!subnode)
+		return dev_err_probe(dev, -ENODEV, "Failed to find DWC3 subnode node\n");
+
+	ret = of_property_read_string(subnode, "maximum-speed", &maximum_speed);
+	of_node_put(subnode);
+	if (ret)
+		return dev_err_probe(dev, -ENODEV, "Failed to determine maximum speed\n");
+
+	priv->use_usb3_flow = !strcmp(maximum_speed, "super-speed-plus") ||
+			      !strcmp(maximum_speed, "super-speed");
+
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to enable runtime PM\n");
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to resume runtime PM\n");
+
+	return devm_of_platform_populate(dev);
+}
+
+static int __maybe_unused dwc3_rcar_gen5_suspend(struct device *dev)
+{
+	struct dwc3_rcar_gen5_priv *priv = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static int __maybe_unused dwc3_rcar_gen5_resume(struct device *dev)
+{
+	struct dwc3_rcar_gen5_priv *priv = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_prepare_enable(priv->clk);
+	if (ret) {
+		dev_err(dev, "Failed to enable clock on resume: %d\n", ret);
+		return ret;
+	}
+
+	usleep_range(10000, 20000);
+
+	return dwc3_rcar_gen5_init(priv);
+}
+
+static DEFINE_RUNTIME_DEV_PM_OPS(dwc3_rcar_gen5_pm_ops,
+				 dwc3_rcar_gen5_suspend,
+				 dwc3_rcar_gen5_resume, NULL);
+
+static const struct of_device_id dwc3_rcar_gen5_of_match[] = {
+	{ .compatible = "renesas,rcar-gen5-usb" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, dwc3_rcar_gen5_of_match);
+
+static struct platform_driver dwc3_rcar_gen5_driver = {
+	.probe		= dwc3_rcar_gen5_probe,
+	.driver		= {
+		.name	= "renesas-rcar-gen5-usb",
+		.of_match_table = dwc3_rcar_gen5_of_match,
+		.pm	= &dwc3_rcar_gen5_pm_ops,
+	},
+};
+
+module_platform_driver(dwc3_rcar_gen5_driver);
+
+MODULE_AUTHOR("Thanh Quan");
+MODULE_DESCRIPTION("Renesas R-Car X5H USB Glue Layer Driver");
+MODULE_LICENSE("GPL");
-- 
2.53.0