phy: Renesas R-Car Gen2 PHY driver

This PHY, though formally being a part of Renesas USBHS controller, contains the
UGCTRL2 register that controls multiplexing of the USB ports (Renesas calls them
channels) to the different USB controllers: channel 0 can be connected to either
PCI EHCI/OHCI or USBHS controllers, channel 2 can be connected to PCI EHCI/OHCI
or xHCI controllers.

This is a new driver for this USB PHY currently already supported under drivers/
usb/phy/. The reason for writing the new driver was the requirement that the
multiplexing of USB channels to the controller be dynamic, depending on what
USB drivers are loaded, rather than static as provided by the old driver. The
infrastructure provided by drivers/phy/phy-core.c seems to fit that purpose
ideally. The new driver only supports device tree probing for now.

Signed-off-by: Sergei Shtylyov <[e-mail]>
Signed-off-by: Kishon Vijay Abraham I <[e-mail]>

Documentation/devicetree/bindings/phy/rcar-gen2-phy.txt

···
+* Renesas R-Car generation 2 USB PHY
+
+This file provides information on what the device node for the R-Car generation
+2 USB PHY contains.
+
+Required properties:
+- compatible: "renesas,usb-phy-r8a7790" if the device is a part of R8A7790 SoC.
+	      "renesas,usb-phy-r8a7791" if the device is a part of R8A7791 SoC.
+- reg: offset and length of the register block.
+- #address-cells: number of address cells for the USB channel subnodes, must
+		  be <1>.
+- #size-cells: number of size cells for the USB channel subnodes, must be <0>.
+- clocks: clock phandle and specifier pair.
+- clock-names: string, clock input name, must be "usbhs".
+
+The USB PHY device tree node should have the subnodes corresponding to the USB
+channels. These subnodes must contain the following properties:
+- reg: the USB controller selector; see the table below for the values.
+- #phy-cells: see phy-bindings.txt in the same directory, must be <1>.
+
+The phandle's argument in the PHY specifier is the USB controller selector for
+the USB channel; see the selector meanings below:
+
++-----------+---------------+---------------+
+|\ Selector |               |               |
++ --------- +       0       |       1       |
+| Channel  \|               |               |
++-----------+---------------+---------------+
+| 0         | PCI EHCI/OHCI | HS-USB        |
+| 2         | PCI EHCI/OHCI | xHCI          |
++-----------+---------------+---------------+
+
+Example (Lager board):
+
+	usb-phy@e6590100 {
+		compatible = "renesas,usb-phy-r8a7790";
+		reg = <0 0xe6590100 0 0x100>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		clocks = <&mstp7_clks R8A7790_CLK_HSUSB>;
+		clock-names = "usbhs";
+
+		usb-channel@0 {
+			reg = <0>;
+			#phy-cells = <1>;
+		};
+		usb-channel@2 {
+			reg = <2>;
+			#phy-cells = <1>;
+		};
+	};

drivers/phy/Kconfig

···
 	  Enable this to support the miphy transceiver (for SATA/PCIE)
 	  that is part of STMicroelectronics STiH41x SoC series.
 
+config PHY_RCAR_GEN2
+	tristate "Renesas R-Car generation 2 USB PHY driver"
+	depends on ARCH_SHMOBILE
+	depends on GENERIC_PHY
+	help
+	  Support for USB PHY found on Renesas R-Car generation 2 SoCs.
+
 config OMAP_CONTROL_PHY
 	tristate "OMAP CONTROL PHY Driver"
 	depends on ARCH_OMAP2PLUS || COMPILE_TEST

drivers/phy/Makefile

···
 obj-$(CONFIG_PHY_EXYNOS_MIPI_VIDEO)	+= phy-exynos-mipi-video.o
 obj-$(CONFIG_PHY_MVEBU_SATA)		+= phy-mvebu-sata.o
 obj-$(CONFIG_PHY_MIPHY365X)		+= phy-miphy365x.o
+obj-$(CONFIG_PHY_RCAR_GEN2)		+= phy-rcar-gen2.o
 obj-$(CONFIG_OMAP_CONTROL_PHY)		+= phy-omap-control.o
 obj-$(CONFIG_OMAP_USB2)			+= phy-omap-usb2.o
 obj-$(CONFIG_TI_PIPE3)			+= phy-ti-pipe3.o

drivers/phy/phy-rcar-gen2.c

···
+/*
+ * Renesas R-Car Gen2 PHY driver
+ *
+ * Copyright (C) 2014 Renesas Solutions Corp.
+ * Copyright (C) 2014 Cogent Embedded, Inc.
+ *
+ * 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/spinlock.h>
+
+#include <asm/cmpxchg.h>
+
+#define USBHS_LPSTS			0x02
+#define USBHS_UGCTRL			0x80
+#define USBHS_UGCTRL2			0x84
+#define USBHS_UGSTS			0x88	/* The manuals have 0x90 */
+
+/* Low Power Status register (LPSTS) */
+#define USBHS_LPSTS_SUSPM		0x4000
+
+/* USB General control register (UGCTRL) */
+#define USBHS_UGCTRL_CONNECT		0x00000004
+#define USBHS_UGCTRL_PLLRESET		0x00000001
+
+/* USB General control register 2 (UGCTRL2) */
+#define USBHS_UGCTRL2_USB2SEL		0x80000000
+#define USBHS_UGCTRL2_USB2SEL_PCI	0x00000000
+#define USBHS_UGCTRL2_USB2SEL_USB30	0x80000000
+#define USBHS_UGCTRL2_USB0SEL		0x00000030
+#define USBHS_UGCTRL2_USB0SEL_PCI	0x00000010
+#define USBHS_UGCTRL2_USB0SEL_HS_USB	0x00000030
+
+/* USB General status register (UGSTS) */
+#define USBHS_UGSTS_LOCK		0x00000300 /* The manuals have 0x3 */
+
+#define PHYS_PER_CHANNEL	2
+
+struct rcar_gen2_phy {
+	struct phy *phy;
+	struct rcar_gen2_channel *channel;
+	int number;
+	u32 select_value;
+};
+
+struct rcar_gen2_channel {
+	struct device_node *of_node;
+	struct rcar_gen2_phy_driver *drv;
+	struct rcar_gen2_phy phys[PHYS_PER_CHANNEL];
+	int selected_phy;
+	u32 select_mask;
+};
+
+struct rcar_gen2_phy_driver {
+	void __iomem *base;
+	struct clk *clk;
+	spinlock_t lock;
+	int num_channels;
+	struct rcar_gen2_channel *channels;
+};
+
+static int rcar_gen2_phy_init(struct phy *p)
+{
+	struct rcar_gen2_phy *phy = phy_get_drvdata(p);
+	struct rcar_gen2_channel *channel = phy->channel;
+	struct rcar_gen2_phy_driver *drv = channel->drv;
+	unsigned long flags;
+	u32 ugctrl2;
+
+	/*
+	 * Try to acquire exclusive access to PHY.  The first driver calling
+	 * phy_init()  on a given channel wins, and all attempts  to use another
+	 * PHY on this channel will fail until phy_exit() is called by the first
+	 * driver.   Achieving this with cmpxcgh() should be SMP-safe.
+	 */
+	if (cmpxchg(&channel->selected_phy, -1, phy->number) != -1)
+		return -EBUSY;
+
+	clk_prepare_enable(drv->clk);
+
+	spin_lock_irqsave(&drv->lock, flags);
+	ugctrl2 = readl(drv->base + USBHS_UGCTRL2);
+	ugctrl2 &= ~channel->select_mask;
+	ugctrl2 |= phy->select_value;
+	writel(ugctrl2, drv->base + USBHS_UGCTRL2);
+	spin_unlock_irqrestore(&drv->lock, flags);
+	return 0;
+}
+
+static int rcar_gen2_phy_exit(struct phy *p)
+{
+	struct rcar_gen2_phy *phy = phy_get_drvdata(p);
+	struct rcar_gen2_channel *channel = phy->channel;
+
+	clk_disable_unprepare(channel->drv->clk);
+
+	channel->selected_phy = -1;
+
+	return 0;
+}
+
+static int rcar_gen2_phy_power_on(struct phy *p)
+{
+	struct rcar_gen2_phy *phy = phy_get_drvdata(p);
+	struct rcar_gen2_phy_driver *drv = phy->channel->drv;
+	void __iomem *base = drv->base;
+	unsigned long flags;
+	u32 value;
+	int err = 0, i;
+
+	/* Skip if it's not USBHS */
+	if (phy->select_value != USBHS_UGCTRL2_USB0SEL_HS_USB)
+		return 0;
+
+	spin_lock_irqsave(&drv->lock, flags);
+
+	/* Power on USBHS PHY */
+	value = readl(base + USBHS_UGCTRL);
+	value &= ~USBHS_UGCTRL_PLLRESET;
+	writel(value, base + USBHS_UGCTRL);
+
+	value = readw(base + USBHS_LPSTS);
+	value |= USBHS_LPSTS_SUSPM;
+	writew(value, base + USBHS_LPSTS);
+
+	for (i = 0; i < 20; i++) {
+		value = readl(base + USBHS_UGSTS);
+		if ((value & USBHS_UGSTS_LOCK) == USBHS_UGSTS_LOCK) {
+			value = readl(base + USBHS_UGCTRL);
+			value |= USBHS_UGCTRL_CONNECT;
+			writel(value, base + USBHS_UGCTRL);
+			goto out;
+		}
+		udelay(1);
+	}
+
+	/* Timed out waiting for the PLL lock */
+	err = -ETIMEDOUT;
+
+out:
+	spin_unlock_irqrestore(&drv->lock, flags);
+
+	return err;
+}
+
+static int rcar_gen2_phy_power_off(struct phy *p)
+{
+	struct rcar_gen2_phy *phy = phy_get_drvdata(p);
+	struct rcar_gen2_phy_driver *drv = phy->channel->drv;
+	void __iomem *base = drv->base;
+	unsigned long flags;
+	u32 value;
+
+	/* Skip if it's not USBHS */
+	if (phy->select_value != USBHS_UGCTRL2_USB0SEL_HS_USB)
+		return 0;
+
+	spin_lock_irqsave(&drv->lock, flags);
+
+	/* Power off USBHS PHY */
+	value = readl(base + USBHS_UGCTRL);
+	value &= ~USBHS_UGCTRL_CONNECT;
+	writel(value, base + USBHS_UGCTRL);
+
+	value = readw(base + USBHS_LPSTS);
+	value &= ~USBHS_LPSTS_SUSPM;
+	writew(value, base + USBHS_LPSTS);
+
+	value = readl(base + USBHS_UGCTRL);
+	value |= USBHS_UGCTRL_PLLRESET;
+	writel(value, base + USBHS_UGCTRL);
+
+	spin_unlock_irqrestore(&drv->lock, flags);
+
+	return 0;
+}
+
+static struct phy_ops rcar_gen2_phy_ops = {
+	.init		= rcar_gen2_phy_init,
+	.exit		= rcar_gen2_phy_exit,
+	.power_on	= rcar_gen2_phy_power_on,
+	.power_off	= rcar_gen2_phy_power_off,
+	.owner		= THIS_MODULE,
+};
+
+static const struct of_device_id rcar_gen2_phy_match_table[] = {
+	{ .compatible = "renesas,usb-phy-r8a7790" },
+	{ .compatible = "renesas,usb-phy-r8a7791" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, rcar_gen2_phy_match_table);
+
+static struct phy *rcar_gen2_phy_xlate(struct device *dev,
+				       struct of_phandle_args *args)
+{
+	struct rcar_gen2_phy_driver *drv;
+	struct device_node *np = args->np;
+	int i;
+
+	if (!of_device_is_available(np)) {
+		dev_warn(dev, "Requested PHY is disabled\n");
+		return ERR_PTR(-ENODEV);
+	}
+
+	drv = dev_get_drvdata(dev);
+	if (!drv)
+		return ERR_PTR(-EINVAL);
+
+	for (i = 0; i < drv->num_channels; i++) {
+		if (np == drv->channels[i].of_node)
+			break;
+	}
+
+	if (i >= drv->num_channels || args->args[0] >= 2)
+		return ERR_PTR(-ENODEV);
+
+	return drv->channels[i].phys[args->args[0]].phy;
+}
+
+static const u32 select_mask[] = {
+	[0]	= USBHS_UGCTRL2_USB0SEL,
+	[2]	= USBHS_UGCTRL2_USB2SEL,
+};
+
+static const u32 select_value[][PHYS_PER_CHANNEL] = {
+	[0]	= { USBHS_UGCTRL2_USB0SEL_PCI, USBHS_UGCTRL2_USB0SEL_HS_USB },
+	[2]	= { USBHS_UGCTRL2_USB2SEL_PCI, USBHS_UGCTRL2_USB2SEL_USB30 },
+};
+
+static int rcar_gen2_phy_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rcar_gen2_phy_driver *drv;
+	struct phy_provider *provider;
+	struct device_node *np;
+	struct resource *res;
+	void __iomem *base;
+	struct clk *clk;
+	int i = 0;
+
+	if (!dev->of_node) {
+		dev_err(dev,
+			"This driver is required to be instantiated from device tree\n");
+		return -EINVAL;
+	}
+
+	clk = devm_clk_get(dev, "usbhs");
+	if (IS_ERR(clk)) {
+		dev_err(dev, "Can't get USBHS clock\n");
+		return PTR_ERR(clk);
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
+	if (!drv)
+		return -ENOMEM;
+
+	spin_lock_init(&drv->lock);
+
+	drv->clk = clk;
+	drv->base = base;
+
+	drv->num_channels = of_get_child_count(dev->of_node);
+	drv->channels = devm_kcalloc(dev, drv->num_channels,
+				     sizeof(struct rcar_gen2_channel),
+				     GFP_KERNEL);
+	if (!drv->channels)
+		return -ENOMEM;
+
+	for_each_child_of_node(dev->of_node, np) {
+		struct rcar_gen2_channel *channel = drv->channels + i;
+		u32 channel_num;
+		int error, n;
+
+		channel->of_node = np;
+		channel->drv = drv;
+		channel->selected_phy = -1;
+
+		error = of_property_read_u32(np, "reg", &channel_num);
+		if (error || channel_num > 2) {
+			dev_err(dev, "Invalid \"reg\" property\n");
+			return error;
+		}
+		channel->select_mask = select_mask[channel_num];
+
+		for (n = 0; n < PHYS_PER_CHANNEL; n++) {
+			struct rcar_gen2_phy *phy = &channel->phys[n];
+
+			phy->channel = channel;
+			phy->number = n;
+			phy->select_value = select_value[channel_num][n];
+
+			phy->phy = devm_phy_create(dev, NULL,
+						   &rcar_gen2_phy_ops, NULL);
+			if (IS_ERR(phy->phy)) {
+				dev_err(dev, "Failed to create PHY\n");
+				return PTR_ERR(phy->phy);
+			}
+			phy_set_drvdata(phy->phy, phy);
+		}
+
+		i++;
+	}
+
+	provider = devm_of_phy_provider_register(dev, rcar_gen2_phy_xlate);
+	if (IS_ERR(provider)) {
+		dev_err(dev, "Failed to register PHY provider\n");
+		return PTR_ERR(provider);
+	}
+
+	dev_set_drvdata(dev, drv);
+
+	return 0;
+}
+
+static struct platform_driver rcar_gen2_phy_driver = {
+	.driver = {
+		.name		= "phy_rcar_gen2",
+		.of_match_table	= rcar_gen2_phy_match_table,
+	},
+	.probe	= rcar_gen2_phy_probe,
+};
+
+module_platform_driver(rcar_gen2_phy_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Renesas R-Car Gen2 PHY");
+MODULE_AUTHOR("Sergei Shtylyov <[e-mail]>");