phy: rcar-gen3-usb3: add support for R-Car Gen3 USB 3.0 PHY

The USB 3.0 PHY modules of R-Car Gen3 SoCs have:
- Spread spectrum clock (ssc).
- Using USB 2.0 EXTAL clock instead of USB 3.0 clock.
- Enabling VBUS detection for usb3.0 peripheral.

So, this driver supports these features.

Signed-off-by: Yoshihiro Shimoda <[e-mail]>
Signed-off-by: Kishon Vijay Abraham I <[e-mail]>

Documentation/devicetree/bindings/phy/rcar-gen3-phy-usb3.txt

···
+* Renesas R-Car generation 3 USB 3.0 PHY
+
+This file provides information on what the device node for the R-Car generation
+3 USB 3.0 PHY contains.
+If you want to enable spread spectrum clock (ssc), you should use USB_EXTAL
+instead of USB3_CLK. However, if you don't want to these features, you don't
+need this driver.
+
+Required properties:
+- compatible: "renesas,r8a7795-usb3-phy" if the device is a part of an R8A7795
+	      SoC.
+	      "renesas,r8a7796-usb3-phy" if the device is a part of an R8A7796
+	      SoC.
+	      "renesas,rcar-gen3-usb3-phy" for a generic R-Car Gen3 compatible
+	      device.
+
+	      When compatible with the generic version, nodes must list the
+	      SoC-specific version corresponding to the platform first
+	      followed by the generic version.
+
+- reg: offset and length of the USB 3.0 PHY register block.
+- clocks: A list of phandles and clock-specifier pairs.
+- clock-names: Name of the clocks.
+  - The funcional clock must be "usb3-if".
+  - The usb3's external clock must be "usb3s_clk".
+  - The usb2's external clock must be "usb_extal". If you want to use the ssc,
+    the clock-frequency must not be 0.
+- #phy-cells: see phy-bindings.txt in the same directory, must be <0>.
+
+Optional properties:
+- renesas,ssc-range: Enable/disable spread spectrum clock (ssc) by using
+		     the following values as u32:
+			- 0 (or the property doesn't exist): disable the ssc
+			- 4980: enable the ssc as -4980 ppm
+			- 4492: enable the ssc as -4492 ppm
+			- 4003: enable the ssc as -4003 ppm
+
+Example (R-Car H3):
+
+	usb-phy@e65ee000 {
+		compatible = "renesas,r8a7795-usb3-phy",
+			     "renesas,rcar-gen3-usb3-phy";
+		reg = <0 0xe65ee000 0 0x90>;
+		clocks = <&cpg CPG_MOD 328>, <&usb3s0_clk>, <&usb_extal>;
+		clock-names = "usb3-if", "usb3s_clk", "usb_extal";
+	};

MAINTAINERS

···
 S:	Supported
 F:	drivers/iio/adc/rcar_gyro_adc.c
 
-RENESAS USB2 PHY DRIVER
+RENESAS USB PHY DRIVER
 M:	Yoshihiro Shimoda <[e-mail]>
 L:	[e-mail]
 S:	Maintained
-F:	drivers/phy/renesas/phy-rcar-gen3-usb2.c
+F:	drivers/phy/renesas/phy-rcar-gen3-usb*.c
 
 RESET CONTROLLER FRAMEWORK
 M:	Philipp Zabel <[e-mail]>

drivers/phy/renesas/Kconfig

···
 	select GENERIC_PHY
 	help
 	  Support for USB 2.0 PHY found on Renesas R-Car generation 3 SoCs.
+
+config PHY_RCAR_GEN3_USB3
+	tristate "Renesas R-Car generation 3 USB 3.0 PHY driver"
+	depends on ARCH_RENESAS || COMPILE_TEST
+	select GENERIC_PHY
+	help
+	  Support for USB 3.0 PHY found on Renesas R-Car generation 3 SoCs.

drivers/phy/renesas/Makefile

···
 obj-$(CONFIG_PHY_RCAR_GEN2)		+= phy-rcar-gen2.o
 obj-$(CONFIG_PHY_RCAR_GEN3_USB2)	+= phy-rcar-gen3-usb2.o
+obj-$(CONFIG_PHY_RCAR_GEN3_USB3)	+= phy-rcar-gen3-usb3.o

drivers/phy/renesas/phy-rcar-gen3-usb3.c

···
+/*
+ * Renesas R-Car Gen3 for USB3.0 PHY driver
+ *
+ * Copyright (C) 2017 Renesas Electronics Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+
+#define USB30_CLKSET0		0x034
+#define USB30_CLKSET1		0x036
+#define USB30_SSC_SET		0x038
+#define USB30_PHY_ENABLE	0x060
+#define USB30_VBUS_EN		0x064
+
+/* USB30_CLKSET0 */
+#define CLKSET0_PRIVATE			0x05c0
+#define CLKSET0_USB30_FSEL_USB_EXTAL	0x0002
+
+/* USB30_CLKSET1 */
+#define CLKSET1_USB30_PLL_MULTI_SHIFT		6
+#define CLKSET1_USB30_PLL_MULTI_USB_EXTAL	(0x64 << \
+						 CLKSET1_USB30_PLL_MULTI_SHIFT)
+#define CLKSET1_PHYRESET	BIT(4)	/* 1: reset */
+#define CLKSET1_REF_CLKDIV	BIT(3)	/* 1: USB_EXTAL */
+#define CLKSET1_PRIVATE_2_1	BIT(1)	/* Write B'01 */
+#define CLKSET1_REF_CLK_SEL	BIT(0)	/* 1: USB3S0_CLK_P */
+
+/* USB30_SSC_SET */
+#define SSC_SET_SSC_EN		BIT(12)
+#define SSC_SET_RANGE_SHIFT	9
+#define SSC_SET_RANGE_4980	(0x0 << SSC_SET_RANGE_SHIFT)
+#define SSC_SET_RANGE_4492	(0x1 << SSC_SET_RANGE_SHIFT)
+#define SSC_SET_RANGE_4003	(0x2 << SSC_SET_RANGE_SHIFT)
+
+/* USB30_PHY_ENABLE */
+#define PHY_ENABLE_RESET_EN	BIT(4)
+
+/* USB30_VBUS_EN */
+#define VBUS_EN_VBUS_EN		BIT(1)
+
+struct rcar_gen3_usb3 {
+	void __iomem *base;
+	struct phy *phy;
+	u32 ssc_range;
+	bool usb3s_clk;
+	bool usb_extal;
+};
+
+static void write_clkset1_for_usb_extal(struct rcar_gen3_usb3 *r, bool reset)
+{
+	u16 val = CLKSET1_USB30_PLL_MULTI_USB_EXTAL |
+		  CLKSET1_REF_CLKDIV | CLKSET1_PRIVATE_2_1;
+
+	if (reset)
+		val |= CLKSET1_PHYRESET;
+
+	writew(val, r->base + USB30_CLKSET1);
+}
+
+static void rcar_gen3_phy_usb3_enable_ssc(struct rcar_gen3_usb3 *r)
+{
+	u16 val = SSC_SET_SSC_EN;
+
+	switch (r->ssc_range) {
+	case 4980:
+		val |= SSC_SET_RANGE_4980;
+		break;
+	case 4492:
+		val |= SSC_SET_RANGE_4492;
+		break;
+	case 4003:
+		val |= SSC_SET_RANGE_4003;
+		break;
+	default:
+		dev_err(&r->phy->dev, "%s: unsupported range (%x)\n", __func__,
+			r->ssc_range);
+		return;
+	}
+
+	writew(val, r->base + USB30_SSC_SET);
+}
+
+static void rcar_gen3_phy_usb3_select_usb_extal(struct rcar_gen3_usb3 *r)
+{
+	write_clkset1_for_usb_extal(r, false);
+	if (r->ssc_range)
+		rcar_gen3_phy_usb3_enable_ssc(r);
+	writew(CLKSET0_PRIVATE | CLKSET0_USB30_FSEL_USB_EXTAL,
+	       r->base + USB30_CLKSET0);
+	writew(PHY_ENABLE_RESET_EN, r->base + USB30_PHY_ENABLE);
+	write_clkset1_for_usb_extal(r, true);
+	usleep_range(10, 20);
+	write_clkset1_for_usb_extal(r, false);
+}
+
+static int rcar_gen3_phy_usb3_init(struct phy *p)
+{
+	struct rcar_gen3_usb3 *r = phy_get_drvdata(p);
+
+	dev_vdbg(&r->phy->dev, "%s: enter (%d, %d, %d)\n", __func__,
+		 r->usb3s_clk, r->usb_extal, r->ssc_range);
+
+	if (!r->usb3s_clk && r->usb_extal)
+		rcar_gen3_phy_usb3_select_usb_extal(r);
+
+	/* Enables VBUS detection anyway */
+	writew(VBUS_EN_VBUS_EN, r->base + USB30_VBUS_EN);
+
+	return 0;
+}
+
+static const struct phy_ops rcar_gen3_phy_usb3_ops = {
+	.init		= rcar_gen3_phy_usb3_init,
+	.owner		= THIS_MODULE,
+};
+
+static const struct of_device_id rcar_gen3_phy_usb3_match_table[] = {
+	{ .compatible = "renesas,rcar-gen3-usb3-phy" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, rcar_gen3_phy_usb3_match_table);
+
+static int rcar_gen3_phy_usb3_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rcar_gen3_usb3 *r;
+	struct phy_provider *provider;
+	struct resource *res;
+	int ret = 0;
+	struct clk *clk;
+
+	if (!dev->of_node) {
+		dev_err(dev, "This driver needs device tree\n");
+		return -EINVAL;
+	}
+
+	r = devm_kzalloc(dev, sizeof(*r), GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	r->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(r->base))
+		return PTR_ERR(r->base);
+
+	clk = devm_clk_get(dev, "usb3s_clk");
+	if (!IS_ERR(clk) && !clk_prepare_enable(clk)) {
+		r->usb3s_clk = !!clk_get_rate(clk);
+		clk_disable_unprepare(clk);
+	}
+	clk = devm_clk_get(dev, "usb_extal");
+	if (!IS_ERR(clk) && !clk_prepare_enable(clk)) {
+		r->usb_extal = !!clk_get_rate(clk);
+		clk_disable_unprepare(clk);
+	}
+
+	if (!r->usb3s_clk && !r->usb_extal) {
+		dev_err(dev, "This driver needs usb3s_clk and/or usb_extal\n");
+		ret = -EINVAL;
+		goto error;
+	}
+
+	/*
+	 * devm_phy_create() will call pm_runtime_enable(&phy->dev);
+	 * And then, phy-core will manage runtime pm for this device.
+	 */
+	pm_runtime_enable(dev);
+
+	r->phy = devm_phy_create(dev, NULL, &rcar_gen3_phy_usb3_ops);
+	if (IS_ERR(r->phy)) {
+		dev_err(dev, "Failed to create USB3 PHY\n");
+		ret = PTR_ERR(r->phy);
+		goto error;
+	}
+
+	of_property_read_u32(dev->of_node, "renesas,ssc-range", &r->ssc_range);
+
+	platform_set_drvdata(pdev, r);
+	phy_set_drvdata(r->phy, r);
+
+	provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+	if (IS_ERR(provider)) {
+		dev_err(dev, "Failed to register PHY provider\n");
+		ret = PTR_ERR(provider);
+		goto error;
+	}
+
+	return 0;
+
+error:
+	pm_runtime_disable(dev);
+
+	return ret;
+}
+
+static int rcar_gen3_phy_usb3_remove(struct platform_device *pdev)
+{
+	pm_runtime_disable(&pdev->dev);
+
+	return 0;
+};
+
+static struct platform_driver rcar_gen3_phy_usb3_driver = {
+	.driver = {
+		.name		= "phy_rcar_gen3_usb3",
+		.of_match_table	= rcar_gen3_phy_usb3_match_table,
+	},
+	.probe	= rcar_gen3_phy_usb3_probe,
+	.remove = rcar_gen3_phy_usb3_remove,
+};
+module_platform_driver(rcar_gen3_phy_usb3_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Renesas R-Car Gen3 USB 3.0 PHY");
+MODULE_AUTHOR("Yoshihiro Shimoda <[e-mail]>");