text: // 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;
  
  	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");
  
  	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->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");
  