[V5,3/6] usb: common: eud: Add driver support for Embedded USB Debugger(EUD)

diff --git a/Documentation/ABI/testing/sysfs-driver-eud b/Documentation/ABI/testing/sysfs-driver-eud
new file mode 100644
index 0000000..83f3872
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-eud
@@ -0,0 +1,9 @@ 
+What:		/sys/bus/platform/drivers/eud/.../enable
+Date:           February 2022
+Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
+Description:
+		The Enable/Disable sysfs interface for Embedded
+		USB Debugger(EUD). This enables and disables the
+		EUD based on a 1 or a 0 value. By enabling EUD,
+		the user is able to activate the mini-usb hub of
+		EUD for debug and trace capabilities.
diff --git a/drivers/usb/common/Kconfig b/drivers/usb/common/Kconfig
index b856622..e4f8b48 100644
--- a/drivers/usb/common/Kconfig
+++ b/drivers/usb/common/Kconfig
@@ -14,6 +14,16 @@  config USB_LED_TRIG
 	  LEDs and you want to use them as activity indicators for USB host or
 	  gadget.

+config USB_QCOM_EUD
+	tristate "QCOM Embedded USB Debugger(EUD) Driver"
+	select USB_ROLE_SWITCH
+	help
+	  This module enables support for Qualcomm Technologies, Inc.
+	  Embedded USB Debugger (EUD). The EUD is a control peripheral
+	  which reports VBUS attach/detach events and has USB-based
+	  debug and trace capabilities. On selecting m, the module name
+	  that is built is qcom_eud.ko
+
 config USB_ULPI_BUS
 	tristate "USB ULPI PHY interface support"
 	select USB_COMMON
diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile
index 8ac4d21..597e48e 100644
--- a/drivers/usb/common/Makefile
+++ b/drivers/usb/common/Makefile
@@ -10,4 +10,5 @@  usb-common-$(CONFIG_USB_LED_TRIG) += led.o

 obj-$(CONFIG_USB_CONN_GPIO)	+= usb-conn-gpio.o
 obj-$(CONFIG_USB_OTG_FSM) += usb-otg-fsm.o
+obj-$(CONFIG_USB_QCOM_EUD) += qcom_eud.o
 obj-$(CONFIG_USB_ULPI_BUS)	+= ulpi.o
diff --git a/drivers/usb/common/qcom_eud.c b/drivers/usb/common/qcom_eud.c
new file mode 100644
index 0000000..84a9884
--- /dev/null
+++ b/drivers/usb/common/qcom_eud.c
@@ -0,0 +1,251 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2015-2021, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/bitops.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/usb/role.h>
+
+#define EUD_REG_INT1_EN_MASK	0x0024
+#define EUD_REG_INT_STATUS_1	0x0044
+#define EUD_REG_CTL_OUT_1	0x0074
+#define EUD_REG_VBUS_INT_CLR	0x0080
+#define EUD_REG_CSR_EUD_EN	0x1014
+#define EUD_REG_SW_ATTACH_DET	0x1018
+#define EUD_REG_EUD_EN2        0x0000
+
+#define EUD_ENABLE		BIT(0)
+#define EUD_INT_PET_EUD	BIT(0)
+#define EUD_INT_VBUS		BIT(2)
+#define EUD_INT_SAFE_MODE	BIT(4)
+#define EUD_INT_ALL		(EUD_INT_VBUS|EUD_INT_SAFE_MODE)
+
+struct eud_chip {
+	struct device			*dev;
+	struct usb_role_switch		*role_sw;
+	void __iomem			*base;
+	void __iomem			*mode_mgr;
+	unsigned int			int_status;
+	int				irq;
+	bool				enabled;
+	bool				usb_attached;
+};
+
+static int enable_eud(struct eud_chip *priv)
+{
+	writel(EUD_ENABLE, priv->base + EUD_REG_CSR_EUD_EN);
+	writel(EUD_INT_VBUS | EUD_INT_SAFE_MODE,
+			priv->base + EUD_REG_INT1_EN_MASK);
+	writel(1, priv->mode_mgr + EUD_REG_EUD_EN2);
+
+	return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
+}
+
+static void disable_eud(struct eud_chip *priv)
+{
+	writel(0, priv->base + EUD_REG_CSR_EUD_EN);
+	writel(0, priv->mode_mgr + EUD_REG_EUD_EN2);
+}
+
+static ssize_t enable_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct eud_chip *chip = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n", chip->enabled);
+}
+
+static ssize_t enable_store(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct eud_chip *chip = dev_get_drvdata(dev);
+	bool enable;
+	int ret;
+
+	if (kstrtobool(buf, &enable))
+		return -EINVAL;
+
+	if (enable) {
+		ret = enable_eud(chip);
+		if (!ret)
+			chip->enabled = enable;
+		else
+			disable_eud(chip);
+	} else {
+		disable_eud(chip);
+	}
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(enable);
+
+static struct attribute *eud_attrs[] = {
+	&dev_attr_enable.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(eud);
+
+static void usb_attach_detach(struct eud_chip *chip)
+{
+	u32 reg;
+
+	/* read ctl_out_1[4] to find USB attach or detach event */
+	reg = readl(chip->base + EUD_REG_CTL_OUT_1);
+	chip->usb_attached = reg & EUD_INT_SAFE_MODE;
+}
+
+static void pet_eud(struct eud_chip *chip)
+{
+	u32 reg;
+	int ret;
+
+	/* When the EUD_INT_PET_EUD in SW_ATTACH_DET is set, the cable has been
+	 * disconnected and we need to detach the pet to check if EUD is in safe
+	 * mode before attaching again.
+	 */
+	reg = readl(chip->base + EUD_REG_SW_ATTACH_DET);
+	if (reg & EUD_INT_PET_EUD) {
+		/* Detach & Attach pet for EUD */
+		writel(0, chip->base + EUD_REG_SW_ATTACH_DET);
+		/* Delay to make sure detach pet is done before attach pet */
+		ret = readl_poll_timeout(chip->base + EUD_REG_SW_ATTACH_DET,
+					reg, (reg == 0), 1, 100);
+		if (ret) {
+			dev_err(chip->dev, "Detach pet failed\n");
+			return;
+		}
+	}
+	/* Attach pet for EUD */
+	writel(EUD_INT_PET_EUD, chip->base +EUD_REG_SW_ATTACH_DET);
+}
+
+static irqreturn_t handle_eud_irq(int irq, void *data)
+{
+	struct eud_chip *chip = data;
+	u32 reg;
+
+	reg = readl(chip->base + EUD_REG_INT_STATUS_1);
+	switch (reg & EUD_INT_ALL) {
+	case EUD_INT_VBUS:
+		usb_attach_detach(chip);
+		return IRQ_WAKE_THREAD;
+	case EUD_INT_SAFE_MODE:
+		pet_eud(chip);
+		return IRQ_HANDLED;
+	default:
+		return IRQ_NONE;
+	}
+}
+
+static irqreturn_t handle_eud_irq_thread(int irq, void *data)
+{
+	struct eud_chip *chip = data;
+	int ret;
+
+	if (chip->usb_attached)
+		ret = usb_role_switch_set_role(chip->role_sw, USB_ROLE_DEVICE);
+	else
+		ret = usb_role_switch_set_role(chip->role_sw, USB_ROLE_HOST);
+	if (ret)
+		dev_err(chip->dev, "failed to set role switch\n");
+
+	/* set and clear vbus_int_clr[0] to clear interrupt */
+	writel(BIT(0), chip->base + EUD_REG_VBUS_INT_CLR);
+	writel(0, chip->base + EUD_REG_VBUS_INT_CLR);
+
+	return IRQ_HANDLED;
+}
+
+static void eud_role_switch_release(void *data)
+{
+	struct eud_chip *chip = data;
+
+	usb_role_switch_put(chip->role_sw);
+}
+
+static int eud_probe(struct platform_device *pdev)
+{
+	struct eud_chip *chip;
+	int ret;
+
+	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->dev = &pdev->dev;
+
+	ret = devm_add_action_or_reset(chip->dev, eud_role_switch_release, chip);
+	if (ret)
+		return dev_err_probe(chip->dev, ret,
+				"failed to add role switch release action\n");
+
+	chip->role_sw = usb_role_switch_get(&pdev->dev);
+	if (IS_ERR(chip->role_sw))
+		return dev_err_probe(chip->dev, PTR_ERR(chip->role_sw),
+					"failed to get role switch\n");
+
+	chip->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(chip->base))
+		return PTR_ERR(chip->base);
+
+	chip->mode_mgr = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(chip->mode_mgr))
+		return PTR_ERR(chip->mode_mgr);
+
+	chip->irq = platform_get_irq(pdev, 0);
+	ret = devm_request_threaded_irq(&pdev->dev, chip->irq, handle_eud_irq,
+			handle_eud_irq_thread, IRQF_ONESHOT, NULL, chip);
+	if (ret)
+		return dev_err_probe(chip->dev, ret, "failed to allocate irq\n");
+
+	enable_irq_wake(chip->irq);
+
+	platform_set_drvdata(pdev, chip);
+
+	return 0;
+}
+
+static int eud_remove(struct platform_device *pdev)
+{
+	struct eud_chip *chip = platform_get_drvdata(pdev);
+
+	if (chip->enabled)
+		disable_eud(chip);
+
+	device_init_wakeup(&pdev->dev, false);
+	disable_irq_wake(chip->irq);
+
+	return 0;
+}
+
+static const struct of_device_id eud_dt_match[] = {
+	{ .compatible = "qcom,sc7280-eud" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, eud_dt_match);
+
+static struct platform_driver eud_driver = {
+	.probe	= eud_probe,
+	.remove	= eud_remove,
+	.driver	= {
+		.name = "qcom_eud",
+		.dev_groups = eud_groups,
+		.of_match_table = eud_dt_match,
+	},
+};
+module_platform_driver(eud_driver);
+
+MODULE_DESCRIPTION("QTI EUD driver");
+MODULE_LICENSE("GPL v2");