phy: starfive: Add JH7110 USB 2.0 PHY driver

Add Starfive JH7110 SoC USB 2.0 PHY driver support.
USB 2.0 PHY default connect to Cadence USB controller.

Signed-off-by: Minda Chen <[e-mail]>
Reviewed-by: Roger Quadros <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

MAINTAINERS

···
 F:	Documentation/devicetree/bindings/watchdog/starfive*
 F:	drivers/watchdog/starfive-wdt.c
 
+STARFIVE JH71X0 USB PHY DRIVER
+M:	Minda Chen <[e-mail]>
+S:	Supported
+F:	Documentation/devicetree/bindings/phy/starfive,jh7110-usb-phy.yaml
+F:	drivers/phy/starfive/phy-jh7110-usb.c
+
 STATIC BRANCH/CALL
 M:	Peter Zijlstra <[e-mail]>
 M:	Josh Poimboeuf <[e-mail]>

drivers/phy/Kconfig

···
 source "drivers/phy/samsung/Kconfig"
 source "drivers/phy/socionext/Kconfig"
 source "drivers/phy/st/Kconfig"
+source "drivers/phy/starfive/Kconfig"
 source "drivers/phy/sunplus/Kconfig"
 source "drivers/phy/tegra/Kconfig"
 source "drivers/phy/ti/Kconfig"

drivers/phy/Makefile

···
 					   samsung/	\
 					   socionext/	\
 					   st/		\
+					   starfive/	\
 					   sunplus/	\
 					   tegra/	\
 					   ti/		\

drivers/phy/starfive/Kconfig

···
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Phy drivers for StarFive platforms
+#
+
+config PHY_STARFIVE_JH7110_USB
+	tristate "Starfive JH7110 USB 2.0 PHY support"
+	depends on USB_SUPPORT
+	select GENERIC_PHY
+	help
+	  Enable this to support the StarFive USB 2.0 PHY,
+	  used with the Cadence USB controller.
+	  If M is selected, the module will be called
+	  phy-jh7110-usb.ko.

drivers/phy/starfive/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_PHY_STARFIVE_JH7110_USB)	+= phy-jh7110-usb.o

drivers/phy/starfive/phy-jh7110-usb.c

···
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * StarFive JH7110 USB 2.0 PHY driver
+ *
+ * Copyright (C) 2023 StarFive Technology Co., Ltd.
+ * Author: Minda Chen <[e-mail]>
+ */
+
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/usb/of.h>
+
+#define USB_125M_CLK_RATE		125000000
+#define USB_LS_KEEPALIVE_OFF		0x4
+#define USB_LS_KEEPALIVE_ENABLE		BIT(4)
+
+struct jh7110_usb2_phy {
+	struct phy *phy;
+	void __iomem *regs;
+	struct clk *usb_125m_clk;
+	struct clk *app_125m;
+	enum phy_mode mode;
+};
+
+static void usb2_set_ls_keepalive(struct jh7110_usb2_phy *phy, bool set)
+{
+	unsigned int val;
+
+	/* Host mode enable the LS speed keep-alive signal */
+	val = readl(phy->regs + USB_LS_KEEPALIVE_OFF);
+	if (set)
+		val |= USB_LS_KEEPALIVE_ENABLE;
+	else
+		val &= ~USB_LS_KEEPALIVE_ENABLE;
+
+	writel(val, phy->regs + USB_LS_KEEPALIVE_OFF);
+}
+
+static int usb2_phy_set_mode(struct phy *_phy,
+			     enum phy_mode mode, int submode)
+{
+	struct jh7110_usb2_phy *phy = phy_get_drvdata(_phy);
+
+	switch (mode) {
+	case PHY_MODE_USB_HOST:
+	case PHY_MODE_USB_DEVICE:
+	case PHY_MODE_USB_OTG:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (mode != phy->mode) {
+		dev_dbg(&_phy->dev, "Changing phy to %d\n", mode);
+		phy->mode = mode;
+		usb2_set_ls_keepalive(phy, (mode != PHY_MODE_USB_DEVICE));
+	}
+
+	return 0;
+}
+
+static int jh7110_usb2_phy_init(struct phy *_phy)
+{
+	struct jh7110_usb2_phy *phy = phy_get_drvdata(_phy);
+	int ret;
+
+	ret = clk_set_rate(phy->usb_125m_clk, USB_125M_CLK_RATE);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(phy->app_125m);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int jh7110_usb2_phy_exit(struct phy *_phy)
+{
+	struct jh7110_usb2_phy *phy = phy_get_drvdata(_phy);
+
+	clk_disable_unprepare(phy->app_125m);
+
+	return 0;
+}
+
+static const struct phy_ops jh7110_usb2_phy_ops = {
+	.init		= jh7110_usb2_phy_init,
+	.exit		= jh7110_usb2_phy_exit,
+	.set_mode	= usb2_phy_set_mode,
+	.owner		= THIS_MODULE,
+};
+
+static int jh7110_usb_phy_probe(struct platform_device *pdev)
+{
+	struct jh7110_usb2_phy *phy;
+	struct device *dev = &pdev->dev;
+	struct phy_provider *phy_provider;
+
+	phy = devm_kzalloc(dev, sizeof(*phy), GFP_KERNEL);
+	if (!phy)
+		return -ENOMEM;
+
+	phy->usb_125m_clk = devm_clk_get(dev, "125m");
+	if (IS_ERR(phy->usb_125m_clk))
+		return dev_err_probe(dev, PTR_ERR(phy->usb_125m_clk),
+			"Failed to get 125m clock\n");
+
+	phy->app_125m = devm_clk_get(dev, "app_125m");
+	if (IS_ERR(phy->app_125m))
+		return dev_err_probe(dev, PTR_ERR(phy->app_125m),
+			"Failed to get app 125m clock\n");
+
+	phy->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(phy->regs))
+		return dev_err_probe(dev, PTR_ERR(phy->regs),
+			"Failed to map phy base\n");
+
+	phy->phy = devm_phy_create(dev, NULL, &jh7110_usb2_phy_ops);
+	if (IS_ERR(phy->phy))
+		return dev_err_probe(dev, PTR_ERR(phy->phy),
+			"Failed to create phy\n");
+
+	phy_set_drvdata(phy->phy, phy);
+	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+
+	return PTR_ERR_OR_ZERO(phy_provider);
+}
+
+static const struct of_device_id jh7110_usb_phy_of_match[] = {
+	{ .compatible = "starfive,jh7110-usb-phy" },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, jh7110_usb_phy_of_match);
+
+static struct platform_driver jh7110_usb_phy_driver = {
+	.probe	= jh7110_usb_phy_probe,
+	.driver = {
+		.of_match_table	= jh7110_usb_phy_of_match,
+		.name  = "jh7110-usb-phy",
+	}
+};
+module_platform_driver(jh7110_usb_phy_driver);
+
+MODULE_DESCRIPTION("StarFive JH7110 USB 2.0 PHY driver");
+MODULE_AUTHOR("Minda Chen <[e-mail]>");
+MODULE_LICENSE("GPL");