// SPDX-License-Identifier: GPL-2.0
/*
 * drd.c - DesignWare USB2 DRD Controller Dual-role support
 *
 * Copyright (C) 2020 STMicroelectronics
 *
 * Author(s): Amelie Delaunay <amelie.delaunay@st.com>
 */

#include <linux/clk.h>
#include <linux/iopoll.h>
#include <linux/platform_device.h>
#include <linux/usb/role.h>
#include "core.h"

#define dwc2_ovr_gotgctl(gotgctl) \
        ((gotgctl) |= GOTGCTL_BVALOEN | GOTGCTL_AVALOEN | GOTGCTL_VBVALOEN | \
         GOTGCTL_DBNCE_FLTR_BYPASS)

static void dwc2_ovr_init(struct dwc2_hsotg *hsotg)
{
        unsigned long flags;
        u32 gotgctl;

        spin_lock_irqsave(&hsotg->lock, flags);

        gotgctl = dwc2_readl(hsotg, GOTGCTL);
        dwc2_ovr_gotgctl(gotgctl);
        gotgctl &= ~(GOTGCTL_BVALOVAL | GOTGCTL_AVALOVAL | GOTGCTL_VBVALOVAL);
        if (hsotg->role_sw_default_mode == USB_DR_MODE_HOST)
                gotgctl |= GOTGCTL_AVALOVAL | GOTGCTL_VBVALOVAL;
        else if (hsotg->role_sw_default_mode == USB_DR_MODE_PERIPHERAL)
                gotgctl |= GOTGCTL_BVALOVAL | GOTGCTL_VBVALOVAL;
        dwc2_writel(hsotg, gotgctl, GOTGCTL);

        spin_unlock_irqrestore(&hsotg->lock, flags);

        dwc2_force_mode(hsotg, (hsotg->dr_mode == USB_DR_MODE_HOST) ||
                                (hsotg->role_sw_default_mode == USB_DR_MODE_HOST));
}

static int dwc2_ovr_avalid(struct dwc2_hsotg *hsotg, bool valid)
{
        u32 gotgctl = dwc2_readl(hsotg, GOTGCTL);

        /* Check if A-Session is already in the right state */
        if ((valid && (gotgctl & GOTGCTL_ASESVLD)) ||
            (!valid && !(gotgctl & GOTGCTL_ASESVLD)))
                return -EALREADY;

        /* Always enable overrides to handle the resume case */
        dwc2_ovr_gotgctl(gotgctl);

        gotgctl &= ~GOTGCTL_BVALOVAL;
        if (valid)
                gotgctl |= GOTGCTL_AVALOVAL | GOTGCTL_VBVALOVAL;
        else
                gotgctl &= ~(GOTGCTL_AVALOVAL | GOTGCTL_VBVALOVAL);
        dwc2_writel(hsotg, gotgctl, GOTGCTL);

        return 0;
}

static int dwc2_ovr_bvalid(struct dwc2_hsotg *hsotg, bool valid)
{
        u32 gotgctl = dwc2_readl(hsotg, GOTGCTL);

        /* Check if B-Session is already in the right state */
        if ((valid && (gotgctl & GOTGCTL_BSESVLD)) ||
            (!valid && !(gotgctl & GOTGCTL_BSESVLD)))
                return -EALREADY;

        /* Always enable overrides to handle the resume case */
        dwc2_ovr_gotgctl(gotgctl);

        gotgctl &= ~GOTGCTL_AVALOVAL;
        if (valid)
                gotgctl |= GOTGCTL_BVALOVAL | GOTGCTL_VBVALOVAL;
        else
                gotgctl &= ~(GOTGCTL_BVALOVAL | GOTGCTL_VBVALOVAL);
        dwc2_writel(hsotg, gotgctl, GOTGCTL);

        return 0;
}

static int dwc2_drd_role_sw_set(struct usb_role_switch *sw, enum usb_role role)
{
        struct dwc2_hsotg *hsotg = usb_role_switch_get_drvdata(sw);
        unsigned long flags;
        int already = 0;

        /* Skip session not in line with dr_mode */
        if ((role == USB_ROLE_DEVICE && hsotg->dr_mode == USB_DR_MODE_HOST) ||
            (role == USB_ROLE_HOST && hsotg->dr_mode == USB_DR_MODE_PERIPHERAL))
                return -EINVAL;

#if IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) || \
        IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE)
        /* Skip session if core is in test mode */
        if (role == USB_ROLE_NONE && hsotg->test_mode) {
                dev_dbg(hsotg->dev, "Core is in test mode\n");
                return -EBUSY;
        }
#endif

        /*
         * In case of USB_DR_MODE_PERIPHERAL, clock is disabled at the end of
         * the probe and enabled on udc_start.
         * If role-switch set is called before the udc_start, we need to enable
         * the clock to read/write GOTGCTL and GUSBCFG registers to override
         * mode and sessions. It is the case if cable is plugged at boot.
         */
        if (!hsotg->ll_hw_enabled && hsotg->clk) {
                int ret = clk_prepare_enable(hsotg->clk);

                if (ret)
                        return ret;
        }

        spin_lock_irqsave(&hsotg->lock, flags);

        if (role == USB_ROLE_NONE) {
                /* default operation mode when usb role is USB_ROLE_NONE */
                if (hsotg->role_sw_default_mode == USB_DR_MODE_HOST)
                        role = USB_ROLE_HOST;
                else if (hsotg->role_sw_default_mode == USB_DR_MODE_PERIPHERAL)
                        role = USB_ROLE_DEVICE;
        }

        if ((IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) ||
             IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE)) &&
             dwc2_is_device_mode(hsotg) &&
             hsotg->lx_state == DWC2_L2 &&
             hsotg->params.power_down == DWC2_POWER_DOWN_PARAM_NONE &&
             hsotg->bus_suspended &&
             !hsotg->params.no_clock_gating)
                dwc2_gadget_exit_clock_gating(hsotg, 0);

        if (role == USB_ROLE_HOST) {
                already = dwc2_ovr_avalid(hsotg, true);
        } else if (role == USB_ROLE_DEVICE) {
                already = dwc2_ovr_bvalid(hsotg, true);
                if (dwc2_is_device_enabled(hsotg)) {
                        /* This clear DCTL.SFTDISCON bit */
                        dwc2_hsotg_core_connect(hsotg);
                }
        } else {
                if (dwc2_is_device_mode(hsotg)) {
                        if (!dwc2_ovr_bvalid(hsotg, false))
                                /* This set DCTL.SFTDISCON bit */
                                dwc2_hsotg_core_disconnect(hsotg);
                } else {
                        dwc2_ovr_avalid(hsotg, false);
                }
        }

        spin_unlock_irqrestore(&hsotg->lock, flags);

        if (!already && hsotg->dr_mode == USB_DR_MODE_OTG)
                /* This will raise a Connector ID Status Change Interrupt */
                dwc2_force_mode(hsotg, role == USB_ROLE_HOST);

        if (!hsotg->ll_hw_enabled && hsotg->clk)
                clk_disable_unprepare(hsotg->clk);

        dev_dbg(hsotg->dev, "%s-session valid\n",
                role == USB_ROLE_NONE ? "No" :
                role == USB_ROLE_HOST ? "A" : "B");

        return 0;
}

int dwc2_drd_init(struct dwc2_hsotg *hsotg)
{
        struct usb_role_switch_desc role_sw_desc = {0};
        struct usb_role_switch *role_sw;
        int ret;

        if (!device_property_read_bool(hsotg->dev, "usb-role-switch"))
                return 0;

        hsotg->role_sw_default_mode = usb_get_role_switch_default_mode(hsotg->dev);
        role_sw_desc.driver_data = hsotg;
        role_sw_desc.fwnode = dev_fwnode(hsotg->dev);
        role_sw_desc.set = dwc2_drd_role_sw_set;
        role_sw_desc.allow_userspace_control = true;

        role_sw = usb_role_switch_register(hsotg->dev, &role_sw_desc);
        if (IS_ERR(role_sw)) {
                ret = PTR_ERR(role_sw);
                dev_err(hsotg->dev,
                        "failed to register role switch: %d\n", ret);
                return ret;
        }

        hsotg->role_sw = role_sw;

        /* Enable override and initialize values */
        dwc2_ovr_init(hsotg);

        return 0;
}

void dwc2_drd_suspend(struct dwc2_hsotg *hsotg)
{
        u32 gintsts, gintmsk;

        if (hsotg->role_sw && !hsotg->params.external_id_pin_ctl) {
                gintmsk = dwc2_readl(hsotg, GINTMSK);
                gintmsk &= ~GINTSTS_CONIDSTSCHNG;
                dwc2_writel(hsotg, gintmsk, GINTMSK);
                gintsts = dwc2_readl(hsotg, GINTSTS);
                dwc2_writel(hsotg, gintsts | GINTSTS_CONIDSTSCHNG, GINTSTS);
        }
}

void dwc2_drd_resume(struct dwc2_hsotg *hsotg)
{
        u32 gintsts, gintmsk;
        enum usb_role role;

        if (hsotg->role_sw) {
                /* get last known role (as the get ops isn't implemented by this driver) */
                role = usb_role_switch_get_role(hsotg->role_sw);

                if (role == USB_ROLE_NONE) {
                        if (hsotg->role_sw_default_mode == USB_DR_MODE_HOST)
                                role = USB_ROLE_HOST;
                        else if (hsotg->role_sw_default_mode == USB_DR_MODE_PERIPHERAL)
                                role = USB_ROLE_DEVICE;
                }

                /* restore last role that may have been lost */
                if (role == USB_ROLE_HOST)
                        dwc2_ovr_avalid(hsotg, true);
                else if (role == USB_ROLE_DEVICE)
                        dwc2_ovr_bvalid(hsotg, true);

                dwc2_force_mode(hsotg, role == USB_ROLE_HOST);

                dev_dbg(hsotg->dev, "resuming %s-session valid\n",
                        role == USB_ROLE_NONE ? "No" :
                        role == USB_ROLE_HOST ? "A" : "B");
        }

        if (hsotg->role_sw && !hsotg->params.external_id_pin_ctl) {
                gintsts = dwc2_readl(hsotg, GINTSTS);
                dwc2_writel(hsotg, gintsts | GINTSTS_CONIDSTSCHNG, GINTSTS);
                gintmsk = dwc2_readl(hsotg, GINTMSK);
                gintmsk |= GINTSTS_CONIDSTSCHNG;
                dwc2_writel(hsotg, gintmsk, GINTMSK);
        }
}

void dwc2_drd_exit(struct dwc2_hsotg *hsotg)
{
        if (hsotg->role_sw)
                usb_role_switch_unregister(hsotg->role_sw);
}