PHY: Add driver for Pistachio USB2.0 PHY

Add a driver for the USB2.0 PHY found on the IMG Pistachio SoC.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: devicetree@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: James Hartley <james.hartley@imgtec.com>
Cc: Damien Horsley <Damien.Horsley@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/9728/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

drivers/phy/Kconfig

@@ -247,6 +247,13 @@ config PHY_EXYNOS5_USBDRD
 	  This driver provides PHY interface for USB 3.0 DRD controller
 	  present on Exynos5 SoC series.
 
+config PHY_PISTACHIO_USB
+	tristate "IMG Pistachio USB2.0 PHY driver"
+	depends on MACH_PISTACHIO
+	select GENERIC_PHY
+	help
+	  Enable this to support the USB2.0 PHY on the IMG Pistachio SoC.
+
 config PHY_QCOM_APQ8064_SATA
 	tristate "Qualcomm APQ8064 SATA SerDes/PHY driver"
 	depends on ARCH_QCOM

drivers/phy/Makefile

@@ -40,3 +40,4 @@ obj-$(CONFIG_PHY_STIH41X_USB)		+= phy-stih41x-usb.o
 obj-$(CONFIG_PHY_QCOM_UFS) 	+= phy-qcom-ufs.o
 obj-$(CONFIG_PHY_QCOM_UFS) 	+= phy-qcom-ufs-qmp-20nm.o
 obj-$(CONFIG_PHY_QCOM_UFS) 	+= phy-qcom-ufs-qmp-14nm.o
+obj-$(CONFIG_PHY_PISTACHIO_USB)		+= phy-pistachio-usb.o

drivers/phy/phy-pistachio-usb.c

@@ -0,0 +1,206 @@
+/*
+ * IMG Pistachio USB PHY driver
+ *
+ * Copyright (C) 2015 Google, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions 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/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include <dt-bindings/phy/phy-pistachio-usb.h>
+
+#define USB_PHY_CONTROL1				0x04
+#define USB_PHY_CONTROL1_FSEL_SHIFT			2
+#define USB_PHY_CONTROL1_FSEL_MASK			0x7
+
+#define USB_PHY_STRAP_CONTROL				0x10
+#define USB_PHY_STRAP_CONTROL_REFCLK_SHIFT		4
+#define USB_PHY_STRAP_CONTROL_REFCLK_MASK		0x3
+
+#define USB_PHY_STATUS					0x14
+#define USB_PHY_STATUS_RX_PHY_CLK			BIT(9)
+#define USB_PHY_STATUS_RX_UTMI_CLK			BIT(8)
+#define USB_PHY_STATUS_VBUS_FAULT			BIT(7)
+
+struct pistachio_usb_phy {
+	struct device *dev;
+	struct regmap *cr_top;
+	struct clk *phy_clk;
+	unsigned int refclk;
+};
+
+static const unsigned long fsel_rate_map[] = {
+	9600000,
+	10000000,
+	12000000,
+	19200000,
+	20000000,
+	24000000,
+	0,
+	50000000,
+};
+
+static int pistachio_usb_phy_power_on(struct phy *phy)
+{
+	struct pistachio_usb_phy *p_phy = phy_get_drvdata(phy);
+	unsigned long timeout, rate;
+	unsigned int i;
+	int ret;
+
+	ret = clk_prepare_enable(p_phy->phy_clk);
+	if (ret < 0) {
+		dev_err(p_phy->dev, "Failed to enable PHY clock: %d\n", ret);
+		return ret;
+	}
+
+	regmap_update_bits(p_phy->cr_top, USB_PHY_STRAP_CONTROL,
+			   USB_PHY_STRAP_CONTROL_REFCLK_MASK <<
+			   USB_PHY_STRAP_CONTROL_REFCLK_SHIFT,
+			   p_phy->refclk << USB_PHY_STRAP_CONTROL_REFCLK_SHIFT);
+
+	rate = clk_get_rate(p_phy->phy_clk);
+	if (p_phy->refclk == REFCLK_XO_CRYSTAL && rate != 12000000) {
+		dev_err(p_phy->dev, "Unsupported rate for XO crystal: %ld\n",
+			rate);
+		ret = -EINVAL;
+		goto disable_clk;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(fsel_rate_map); i++) {
+		if (rate == fsel_rate_map[i])
+			break;
+	}
+	if (i == ARRAY_SIZE(fsel_rate_map)) {
+		dev_err(p_phy->dev, "Unsupported clock rate: %lu\n", rate);
+		ret = -EINVAL;
+		goto disable_clk;
+	}
+
+	regmap_update_bits(p_phy->cr_top, USB_PHY_CONTROL1,
+			   USB_PHY_CONTROL1_FSEL_MASK <<
+			   USB_PHY_CONTROL1_FSEL_SHIFT,
+			   i << USB_PHY_CONTROL1_FSEL_SHIFT);
+
+	timeout = jiffies + msecs_to_jiffies(200);
+	while (time_before(jiffies, timeout)) {
+		unsigned int val;
+
+		regmap_read(p_phy->cr_top, USB_PHY_STATUS, &val);
+		if (val & USB_PHY_STATUS_VBUS_FAULT) {
+			dev_err(p_phy->dev, "VBUS fault detected\n");
+			ret = -EIO;
+			goto disable_clk;
+		}
+		if ((val & USB_PHY_STATUS_RX_PHY_CLK) &&
+		    (val & USB_PHY_STATUS_RX_UTMI_CLK))
+			return 0;
+		usleep_range(1000, 1500);
+	}
+
+	dev_err(p_phy->dev, "Timed out waiting for PHY to power on\n");
+	ret = -ETIMEDOUT;
+
+disable_clk:
+	clk_disable_unprepare(p_phy->phy_clk);
+	return ret;
+}
+
+static int pistachio_usb_phy_power_off(struct phy *phy)
+{
+	struct pistachio_usb_phy *p_phy = phy_get_drvdata(phy);
+
+	clk_disable_unprepare(p_phy->phy_clk);
+
+	return 0;
+}
+
+static const struct phy_ops pistachio_usb_phy_ops = {
+	.power_on = pistachio_usb_phy_power_on,
+	.power_off = pistachio_usb_phy_power_off,
+	.owner = THIS_MODULE,
+};
+
+static int pistachio_usb_phy_probe(struct platform_device *pdev)
+{
+	struct pistachio_usb_phy *p_phy;
+	struct phy_provider *provider;
+	struct phy *phy;
+	int ret;
+
+	p_phy = devm_kzalloc(&pdev->dev, sizeof(*p_phy), GFP_KERNEL);
+	if (!p_phy)
+		return -ENOMEM;
+	p_phy->dev = &pdev->dev;
+	platform_set_drvdata(pdev, p_phy);
+
+	p_phy->cr_top = syscon_regmap_lookup_by_phandle(p_phy->dev->of_node,
+							"img,cr-top");
+	if (IS_ERR(p_phy->cr_top)) {
+		dev_err(p_phy->dev, "Failed to get CR_TOP registers: %ld\n",
+			PTR_ERR(p_phy->cr_top));
+		return PTR_ERR(p_phy->cr_top);
+	}
+
+	p_phy->phy_clk = devm_clk_get(p_phy->dev, "usb_phy");
+	if (IS_ERR(p_phy->phy_clk)) {
+		dev_err(p_phy->dev, "Failed to get usb_phy clock: %ld\n",
+			PTR_ERR(p_phy->phy_clk));
+		return PTR_ERR(p_phy->phy_clk);
+	}
+
+	ret = of_property_read_u32(p_phy->dev->of_node, "img,refclk",
+				   &p_phy->refclk);
+	if (ret < 0) {
+		dev_err(p_phy->dev, "No reference clock selector specified\n");
+		return ret;
+	}
+
+	phy = devm_phy_create(p_phy->dev, NULL, &pistachio_usb_phy_ops);
+	if (IS_ERR(phy)) {
+		dev_err(p_phy->dev, "Failed to create PHY: %ld\n",
+			PTR_ERR(phy));
+		return PTR_ERR(phy);
+	}
+	phy_set_drvdata(phy, p_phy);
+
+	provider = devm_of_phy_provider_register(p_phy->dev,
+						 of_phy_simple_xlate);
+	if (IS_ERR(provider)) {
+		dev_err(p_phy->dev, "Failed to register PHY provider: %ld\n",
+			PTR_ERR(provider));
+		return PTR_ERR(provider);
+	}
+
+	return 0;
+}
+
+static const struct of_device_id pistachio_usb_phy_of_match[] = {
+	{ .compatible = "img,pistachio-usb-phy", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, pistachio_usb_phy_of_match);
+
+static struct platform_driver pistachio_usb_phy_driver = {
+	.probe		= pistachio_usb_phy_probe,
+	.driver		= {
+		.name	= "pistachio-usb-phy",
+		.of_match_table = pistachio_usb_phy_of_match,
+	},
+};
+module_platform_driver(pistachio_usb_phy_driver);
+
+MODULE_AUTHOR("Andrew Bresticker <abrestic@chromium.org>");
+MODULE_DESCRIPTION("IMG Pistachio USB2.0 PHY driver");
+MODULE_LICENSE("GPL v2");