// 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>
#include <linux/firmware/qcom/qcom_scm.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;
        phys_addr_t                     mode_mgr;
        unsigned int                    int_status;
        int                             irq;
        bool                            enabled;
        bool                            usb_attached;
};

static int enable_eud(struct eud_chip *priv)
{
        int ret;

        ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 1);
        if (ret)
                return ret;

        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);

        return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
}

static int disable_eud(struct eud_chip *priv)
{
        int ret;

        ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 0);
        if (ret)
                return ret;

        writel(0, priv->base + EUD_REG_CSR_EUD_EN);
        return 0;
}

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 {
                ret = disable_eud(chip);
        }

        return ret < 0 ? ret : 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;
        struct resource *res;
        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 ret;

        chip->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(chip->base))
                return PTR_ERR(chip->base);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (!res)
                return -ENODEV;
        chip->mode_mgr = res->start;

        chip->irq = platform_get_irq(pdev, 0);
        if (chip->irq < 0)
                return chip->irq;

        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 void 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);
}

static const struct of_device_id eud_dt_match[] = {
        { .compatible = "qcom,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");