// SPDX-License-Identifier: GPL-2.0
/*
 * dwc3-google.c - Google DWC3 Specific Glue Layer
 *
 * Copyright (c) 2025, Google LLC
 * Author: Roy Luo <royluo@google.com>
 */

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/iopoll.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_domain.h>
#include <linux/regmap.h>
#include <linux/reset.h>
#include "core.h"
#include "glue.h"

/* HOST CFG registers */
#define HC_STATUS_OFFSET 0x0
#define HC_STATUS_CURRENT_POWER_STATE_U2PMU GENMASK(1, 0)
#define HC_STATUS_CURRENT_POWER_STATE_U3PMU GENMASK(4, 3)

#define HOST_CFG1_OFFSET 0x4
#define HOST_CFG1_PME_EN BIT(3)
#define HOST_CFG1_PM_POWER_STATE_REQUEST GENMASK(5, 4)
#define HOST_CFG1_PM_POWER_STATE_D0 0x0
#define HOST_CFG1_PM_POWER_STATE_D3 0x3

/* USBINT registers */
#define USBINT_CFG1_OFFSET 0x0
#define USBINT_CFG1_USBDRD_PME_GEN_U2P_INTR_MSK BIT(2)
#define USBINT_CFG1_USBDRD_PME_GEN_U3P_INTR_MSK BIT(3)
#define USBINT_CFG1_USBDRD_PME_GEN_U2P_INTR_INT_EN BIT(8)
#define USBINT_CFG1_USBDRD_PME_GEN_U3P_INTR_INT_EN BIT(9)
#define USBINT_CFG1_USBDRD_PME_GEN_U2_INTR_CLR BIT(14)
#define USBINT_CFG1_USBDRD_PME_GEN_U3_INTR_CLR BIT(15)

#define USBINT_STATUS_OFFSET 0x4
#define USBINT_STATUS_USBDRD_PME_GEN_U2P_INTR_STS_RAW BIT(2)
#define USBINT_STATUS_USBDRD_PME_GEN_U3P_INTR_STS_RAW BIT(3)

#define USBCS_TOP_CTRL_CFG1_OFFSET 0xc
#define USBCS_TOP_CTRL_CFG1_USB2ONLY_MODE BIT(5)

#define DWC3_GOOGLE_MAX_RESETS  4

struct dwc3_google {
        struct device           *dev;
        struct dwc3             dwc;
        struct clk_bulk_data    *clks;
        int                     num_clks;
        struct reset_control_bulk_data rsts[DWC3_GOOGLE_MAX_RESETS];
        int                     num_rsts;
        struct reset_control    *non_sticky_rst;
        struct device           *usb_psw_pd;
        struct device_link      *usb_psw_pd_dl;
        struct notifier_block   usb_psw_pd_nb;
        struct device           *usb_top_pd;
        struct device_link      *usb_top_pd_dl;
        struct regmap           *usb_cfg_regmap;
        unsigned int            host_cfg_offset;
        unsigned int            usbint_cfg_offset;
        int                     hs_pme_irq;
        int                     ss_pme_irq;
        bool                    is_usb2only;
        bool                    is_hibernation;
};

#define to_dwc3_google(d) container_of_const((d), struct dwc3_google, dwc)

static int dwc3_google_rst_init(struct dwc3_google *google)
{
        int ret;

        google->num_rsts = 4;
        google->rsts[0].id = "non_sticky";
        google->rsts[1].id = "sticky";
        google->rsts[2].id = "drd_bus";
        google->rsts[3].id = "top";

        ret = devm_reset_control_bulk_get_exclusive(google->dev,
                                                    google->num_rsts,
                                                    google->rsts);

        if (ret < 0)
                return ret;

        google->non_sticky_rst = google->rsts[0].rstc;

        return 0;
}

static int dwc3_google_set_pmu_state(struct dwc3_google *google, int state)
{
        u32 reg;
        int ret;

        regmap_read(google->usb_cfg_regmap,
                    google->host_cfg_offset + HOST_CFG1_OFFSET, &reg);

        reg &= ~HOST_CFG1_PM_POWER_STATE_REQUEST;
        reg |= (FIELD_PREP(HOST_CFG1_PM_POWER_STATE_REQUEST, state) |
                HOST_CFG1_PME_EN);
        regmap_write(google->usb_cfg_regmap,
                     google->host_cfg_offset + HOST_CFG1_OFFSET, reg);

        ret = regmap_read_poll_timeout(google->usb_cfg_regmap,
                                       google->host_cfg_offset + HC_STATUS_OFFSET, reg,
                                       (FIELD_GET(HC_STATUS_CURRENT_POWER_STATE_U2PMU,
                                                  reg) == state &&
                                        FIELD_GET(HC_STATUS_CURRENT_POWER_STATE_U3PMU,
                                                  reg) == state),
                                       10, 10000);

        if (ret)
                dev_err(google->dev, "failed to set PMU state %d\n", state);

        return ret;
}

/*
 * Clear pme interrupts and report their status.
 * The hardware requires write-1 then write-0 sequence to clear the interrupt bits.
 */
static u32 dwc3_google_clear_pme_irqs(struct dwc3_google *google)
{
        u32 irq_status, reg_set, reg_clear;

        regmap_read(google->usb_cfg_regmap,
                    google->usbint_cfg_offset + USBINT_STATUS_OFFSET, &irq_status);

        irq_status &= (USBINT_STATUS_USBDRD_PME_GEN_U2P_INTR_STS_RAW |
                       USBINT_STATUS_USBDRD_PME_GEN_U3P_INTR_STS_RAW);
        if (!irq_status)
                return irq_status;

        regmap_read(google->usb_cfg_regmap,
                    google->usbint_cfg_offset + USBINT_CFG1_OFFSET, &reg_set);

        reg_clear = reg_set;
        if (irq_status & USBINT_STATUS_USBDRD_PME_GEN_U2P_INTR_STS_RAW) {
                reg_set |= USBINT_CFG1_USBDRD_PME_GEN_U2_INTR_CLR;
                reg_clear &= ~USBINT_CFG1_USBDRD_PME_GEN_U2_INTR_CLR;
        }
        if (irq_status & USBINT_STATUS_USBDRD_PME_GEN_U3P_INTR_STS_RAW) {
                reg_set |= USBINT_CFG1_USBDRD_PME_GEN_U3_INTR_CLR;
                reg_clear &= ~USBINT_CFG1_USBDRD_PME_GEN_U3_INTR_CLR;
        }

        regmap_write(google->usb_cfg_regmap,
                     google->usbint_cfg_offset + USBINT_CFG1_OFFSET, reg_set);
        regmap_write(google->usb_cfg_regmap,
                     google->usbint_cfg_offset + USBINT_CFG1_OFFSET, reg_clear);

        return irq_status;
}

static void dwc3_google_enable_pme_irq(struct dwc3_google *google)
{
        u32 reg;

        regmap_read(google->usb_cfg_regmap,
                    google->usbint_cfg_offset + USBINT_CFG1_OFFSET, &reg);
        reg &= ~(USBINT_CFG1_USBDRD_PME_GEN_U2P_INTR_MSK |
                 USBINT_CFG1_USBDRD_PME_GEN_U3P_INTR_MSK);
        reg |= (USBINT_CFG1_USBDRD_PME_GEN_U2P_INTR_INT_EN |
                USBINT_CFG1_USBDRD_PME_GEN_U3P_INTR_INT_EN);
        regmap_write(google->usb_cfg_regmap,
                     google->usbint_cfg_offset + USBINT_CFG1_OFFSET, reg);

        enable_irq(google->hs_pme_irq);
        enable_irq(google->ss_pme_irq);
        enable_irq_wake(google->hs_pme_irq);
        enable_irq_wake(google->ss_pme_irq);
}

static void dwc3_google_disable_pme_irq(struct dwc3_google *google)
{
        u32 reg;

        regmap_read(google->usb_cfg_regmap,
                    google->usbint_cfg_offset + USBINT_CFG1_OFFSET, &reg);
        reg &= ~(USBINT_CFG1_USBDRD_PME_GEN_U2P_INTR_INT_EN |
                 USBINT_CFG1_USBDRD_PME_GEN_U3P_INTR_INT_EN);
        reg |= (USBINT_CFG1_USBDRD_PME_GEN_U2P_INTR_MSK |
                USBINT_CFG1_USBDRD_PME_GEN_U3P_INTR_MSK);
        regmap_write(google->usb_cfg_regmap,
                     google->usbint_cfg_offset + USBINT_CFG1_OFFSET, reg);

        disable_irq_wake(google->hs_pme_irq);
        disable_irq_wake(google->ss_pme_irq);
        disable_irq_nosync(google->hs_pme_irq);
        disable_irq_nosync(google->ss_pme_irq);
}

static irqreturn_t dwc3_google_resume_irq(int irq, void *data)
{
        struct dwc3_google      *google = data;
        struct dwc3             *dwc = &google->dwc;
        u32 irq_status, dr_role;

        irq_status = dwc3_google_clear_pme_irqs(google);
        dr_role = dwc->current_dr_role;

        if (!irq_status || !google->is_hibernation ||
            dr_role != DWC3_GCTL_PRTCAP_HOST) {
                dev_dbg(google->dev, "spurious pme irq %d, hibernation %d, dr_role %u\n",
                        irq, google->is_hibernation, dr_role);
                return IRQ_HANDLED;
        }

        if (dwc->xhci)
                pm_runtime_resume(&dwc->xhci->dev);

        return IRQ_HANDLED;
}

static int dwc3_google_request_irq(struct dwc3_google *google, struct platform_device *pdev,
                                   const char *irq_name, const char *req_name)
{
        int ret;
        int irq;

        irq = platform_get_irq_byname(pdev, irq_name);
        if (irq < 0)
                return irq;

        irq_set_status_flags(irq, IRQ_NOAUTOEN);
        ret = devm_request_threaded_irq(google->dev, irq, NULL,
                                        dwc3_google_resume_irq,
                                        IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
                                        req_name, google);
        if (ret < 0) {
                dev_err(google->dev, "failed to request irq %s\n", req_name);
                return ret;
        }

        return irq;
}

static int dwc3_google_usb_psw_pd_notifier(struct notifier_block *nb, unsigned long action, void *d)
{
        struct dwc3_google *google = container_of(nb, struct dwc3_google, usb_psw_pd_nb);
        int ret;

        if (!google->is_hibernation)
                return NOTIFY_OK;

        if (action == GENPD_NOTIFY_OFF) {
                dev_dbg(google->dev, "enter D3 power state\n");
                dwc3_google_set_pmu_state(google, HOST_CFG1_PM_POWER_STATE_D3);
                ret = reset_control_assert(google->non_sticky_rst);
                if (ret)
                        dev_err(google->dev, "non sticky reset assert failed: %d\n", ret);
        } else if (action == GENPD_NOTIFY_ON) {
                dev_dbg(google->dev, "enter D0 power state\n");
                dwc3_google_clear_pme_irqs(google);
                ret = reset_control_deassert(google->non_sticky_rst);
                if (ret)
                        dev_err(google->dev, "non sticky reset deassert failed: %d\n", ret);
                dwc3_google_set_pmu_state(google, HOST_CFG1_PM_POWER_STATE_D0);
        }

        return NOTIFY_OK;
}

static void dwc3_google_pm_domain_deinit(struct dwc3_google *google)
{
        if (google->usb_top_pd_dl)
                device_link_del(google->usb_top_pd_dl);

        if (!IS_ERR_OR_NULL(google->usb_top_pd)) {
                device_set_wakeup_capable(google->usb_top_pd, false);
                dev_pm_domain_detach(google->usb_top_pd, true);
        }

        if (google->usb_psw_pd_dl)
                device_link_del(google->usb_psw_pd_dl);

        if (!IS_ERR_OR_NULL(google->usb_psw_pd)) {
                dev_pm_genpd_remove_notifier(google->usb_psw_pd);
                dev_pm_domain_detach(google->usb_psw_pd, true);
        }
}

static int dwc3_google_pm_domain_init(struct dwc3_google *google)
{
        int ret;

        /*
         * Establish PM RUNTIME link between dwc dev and its power domain usb_psw_pd,
         * register notifier block to handle hibernation.
         */
        google->usb_psw_pd = dev_pm_domain_attach_by_name(google->dev, "psw");
        if (IS_ERR_OR_NULL(google->usb_psw_pd)) {
                dev_err(google->dev, "failed to get psw pd");
                ret = google->usb_psw_pd ? PTR_ERR(google->usb_psw_pd) : -ENODATA;
                return ret;
        }

        google->usb_psw_pd_nb.notifier_call = dwc3_google_usb_psw_pd_notifier;
        ret = dev_pm_genpd_add_notifier(google->usb_psw_pd, &google->usb_psw_pd_nb);
        if (ret) {
                dev_err(google->dev, "failed to add psw pd notifier");
                goto err;
        }

        google->usb_psw_pd_dl = device_link_add(google->dev, google->usb_psw_pd,
                                                DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME |
                                                DL_FLAG_RPM_ACTIVE);
        if (!google->usb_psw_pd_dl) {
                dev_err(google->usb_psw_pd, "failed to add device link");
                ret = -ENODEV;
                goto err;
        }

        /*
         * usb_top_pd is the parent power domain of usb_psw_pd. Keeping usb_top_pd on
         * while usb_psw_pd is off places the controller in a power-gated state,
         * essential for hibernation. Acquire a handle to usb_top_pd and sets it as
         * wakeup-capable to allow the domain to be left on during system suspend.
         */
        google->usb_top_pd = dev_pm_domain_attach_by_name(google->dev, "top");
        if (IS_ERR_OR_NULL(google->usb_top_pd)) {
                dev_err(google->dev, "failed to get top pd");
                ret = google->usb_top_pd ? PTR_ERR(google->usb_top_pd) : -ENODATA;
                goto err;
        }
        device_set_wakeup_capable(google->usb_top_pd, true);

        google->usb_top_pd_dl = device_link_add(google->dev, google->usb_top_pd,
                                                DL_FLAG_STATELESS);
        if (!google->usb_top_pd_dl) {
                dev_err(google->usb_top_pd, "failed to add device link");
                ret = -ENODEV;
                goto err;
        }

        return 0;

err:
        dwc3_google_pm_domain_deinit(google);

        return ret;
}

static void dwc3_google_program_usb2only(struct dwc3_google *google)
{
        u32 reg;

        regmap_read(google->usb_cfg_regmap,
                    google->usbint_cfg_offset + USBCS_TOP_CTRL_CFG1_OFFSET, &reg);
        reg |= USBCS_TOP_CTRL_CFG1_USB2ONLY_MODE;
        regmap_write(google->usb_cfg_regmap,
                     google->usbint_cfg_offset + USBCS_TOP_CTRL_CFG1_OFFSET, reg);
}

static int dwc3_google_probe(struct platform_device *pdev)
{
        struct dwc3_probe_data  probe_data = {};
        struct device           *dev = &pdev->dev;
        struct dwc3_google      *google;
        struct resource         *res;
        int                     ret;
        u32                     args[2];

        google = devm_kzalloc(&pdev->dev, sizeof(*google), GFP_KERNEL);
        if (!google)
                return -ENOMEM;

        google->dev = &pdev->dev;

        ret = dwc3_google_pm_domain_init(google);
        if (ret < 0)
                return dev_err_probe(dev, ret, "failed to init pdom\n");

        google->usb_cfg_regmap =
                syscon_regmap_lookup_by_phandle_args(dev->of_node,
                                                     "google,usb-cfg-csr",
                                                     ARRAY_SIZE(args), args);
        if (IS_ERR(google->usb_cfg_regmap)) {
                ret = dev_err_probe(dev, PTR_ERR(google->usb_cfg_regmap),
                                    "invalid usb cfg csr\n");
                goto err_deinit_pdom;
        }

        google->host_cfg_offset = args[0];
        google->usbint_cfg_offset = args[1];

        if (device_property_match_string(dev, "phy-names", "usb3-phy") < 0) {
                google->is_usb2only = true;
                dwc3_google_program_usb2only(google);
        }

        ret = devm_clk_bulk_get_all_enabled(dev, &google->clks);
        if (ret < 0) {
                ret = dev_err_probe(dev, ret, "failed to get and enable clks\n");
                goto err_deinit_pdom;
        }
        google->num_clks = ret;

        ret = dwc3_google_rst_init(google);
        if (ret) {
                ret = dev_err_probe(dev, ret, "failed to get resets\n");
                goto err_deinit_pdom;
        }

        ret = reset_control_bulk_deassert(google->num_rsts, google->rsts);
        if (ret) {
                ret = dev_err_probe(dev, ret, "failed to deassert rsts\n");
                goto err_deinit_pdom;
        }

        ret = dwc3_google_request_irq(google, pdev, "hs_pme", "USB HS wakeup");
        if (ret < 0) {
                ret = dev_err_probe(dev, ret, "failed to request hs pme irq");
                goto err_reset_assert;
        }
        google->hs_pme_irq = ret;

        ret = dwc3_google_request_irq(google, pdev, "ss_pme", "USB SS wakeup");
        if (ret < 0) {
                ret = dev_err_probe(dev, ret, "failed to request ss pme irq");
                goto err_reset_assert;
        }
        google->ss_pme_irq = ret;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                ret = dev_err_probe(dev, -ENODEV, "invalid memory\n");
                goto err_reset_assert;
        }

        device_init_wakeup(dev, true);

        google->dwc.dev = dev;
        probe_data.dwc = &google->dwc;
        probe_data.res = res;
        probe_data.ignore_clocks_and_resets = true;
        ret = dwc3_core_probe(&probe_data);
        if (ret)  {
                ret = dev_err_probe(dev, ret, "failed to register DWC3 Core\n");
                goto err_reset_assert;
        }

        return 0;

err_reset_assert:
        reset_control_bulk_assert(google->num_rsts, google->rsts);

err_deinit_pdom:
        dwc3_google_pm_domain_deinit(google);

        return ret;
}

static void dwc3_google_remove(struct platform_device *pdev)
{
        struct dwc3 *dwc = platform_get_drvdata(pdev);
        struct dwc3_google *google = to_dwc3_google(dwc);

        dwc3_core_remove(&google->dwc);

        reset_control_bulk_assert(google->num_rsts, google->rsts);

        dwc3_google_pm_domain_deinit(google);
}

static int dwc3_google_suspend(struct dwc3_google *google, pm_message_t msg)
{
        if (pm_runtime_suspended(google->dev))
                return 0;

        if (google->dwc.current_dr_role == DWC3_GCTL_PRTCAP_HOST) {
                /*
                 * Follow dwc3_suspend_common() guidelines for deciding between
                 * a full teardown and hibernation.
                 */
                if (PMSG_IS_AUTO(msg) || device_may_wakeup(google->dev)) {
                        dev_dbg(google->dev, "enter hibernation");
                        pm_runtime_get_sync(google->usb_top_pd);
                        device_wakeup_enable(google->usb_top_pd);
                        dwc3_google_enable_pme_irq(google);
                        google->is_hibernation = true;
                        return 0;
                }
        }

        reset_control_bulk_assert(google->num_rsts, google->rsts);
        clk_bulk_disable_unprepare(google->num_clks, google->clks);

        return 0;
}

static int dwc3_google_resume(struct dwc3_google *google, pm_message_t msg)
{
        int ret;

        if (google->is_hibernation) {
                dev_dbg(google->dev, "exit hibernation");
                dwc3_google_disable_pme_irq(google);
                device_wakeup_disable(google->usb_top_pd);
                pm_runtime_put_sync(google->usb_top_pd);
                google->is_hibernation = false;
                return 0;
        }

        if (google->is_usb2only)
                dwc3_google_program_usb2only(google);

        ret = clk_bulk_prepare_enable(google->num_clks, google->clks);
        if (ret)
                return ret;

        ret = reset_control_bulk_deassert(google->num_rsts, google->rsts);
        if (ret) {
                clk_bulk_disable_unprepare(google->num_clks, google->clks);
                return ret;
        }

        return 0;
}

static int dwc3_google_pm_suspend(struct device *dev)
{
        struct dwc3 *dwc = dev_get_drvdata(dev);
        struct dwc3_google *google = to_dwc3_google(dwc);
        int ret;

        ret = dwc3_pm_suspend(&google->dwc);
        if (ret)
                return ret;

        return dwc3_google_suspend(google, PMSG_SUSPEND);
}

static int dwc3_google_pm_resume(struct device *dev)
{
        struct dwc3 *dwc = dev_get_drvdata(dev);
        struct dwc3_google *google = to_dwc3_google(dwc);
        int ret;

        ret = dwc3_google_resume(google, PMSG_RESUME);
        if (ret)
                return ret;

        return dwc3_pm_resume(&google->dwc);
}

static void dwc3_google_complete(struct device *dev)
{
        struct dwc3 *dwc = dev_get_drvdata(dev);

        dwc3_pm_complete(dwc);
}

static int dwc3_google_prepare(struct device *dev)
{
        struct dwc3 *dwc = dev_get_drvdata(dev);

        return dwc3_pm_prepare(dwc);
}

static int dwc3_google_runtime_suspend(struct device *dev)
{
        struct dwc3 *dwc = dev_get_drvdata(dev);
        struct dwc3_google *google = to_dwc3_google(dwc);
        int ret;

        ret = dwc3_runtime_suspend(&google->dwc);
        if (ret)
                return ret;

        return dwc3_google_suspend(google, PMSG_AUTO_SUSPEND);
}

static int dwc3_google_runtime_resume(struct device *dev)
{
        struct dwc3 *dwc = dev_get_drvdata(dev);
        struct dwc3_google *google = to_dwc3_google(dwc);
        int ret;

        ret = dwc3_google_resume(google, PMSG_AUTO_RESUME);
        if (ret)
                return ret;

        return dwc3_runtime_resume(&google->dwc);
}

static int dwc3_google_runtime_idle(struct device *dev)
{
        return dwc3_runtime_idle(dev_get_drvdata(dev));
}

static const struct dev_pm_ops dwc3_google_dev_pm_ops = {
        SYSTEM_SLEEP_PM_OPS(dwc3_google_pm_suspend, dwc3_google_pm_resume)
        RUNTIME_PM_OPS(dwc3_google_runtime_suspend, dwc3_google_runtime_resume,
                       dwc3_google_runtime_idle)
        .complete = pm_sleep_ptr(dwc3_google_complete),
        .prepare = pm_sleep_ptr(dwc3_google_prepare),
};

static const struct of_device_id dwc3_google_of_match[] = {
        { .compatible = "google,lga-dwc3" },
        { }
};
MODULE_DEVICE_TABLE(of, dwc3_google_of_match);

static struct platform_driver dwc3_google_driver = {
        .probe          = dwc3_google_probe,
        .remove         = dwc3_google_remove,
        .driver         = {
                .name   = "dwc3-google",
                .pm     = pm_ptr(&dwc3_google_dev_pm_ops),
                .of_match_table = dwc3_google_of_match,
        },
};

module_platform_driver(dwc3_google_driver);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("DesignWare DWC3 Google Glue Driver");