// SPDX-License-Identifier: GPL-2.0
/*
 * mtu3_dr.c - dual role switch and host glue layer
 *
 * Copyright (C) 2016 MediaTek Inc.
 *
 * Author: Chunfeng Yun <chunfeng.yun@mediatek.com>
 */

#include <linux/string_choices.h>
#include "mtu3.h"
#include "mtu3_dr.h"
#include "mtu3_debug.h"

#define USB2_PORT 2
#define USB3_PORT 3

static inline struct ssusb_mtk *otg_sx_to_ssusb(struct otg_switch_mtk *otg_sx)
{
        return container_of(otg_sx, struct ssusb_mtk, otg_switch);
}

static void toggle_opstate(struct ssusb_mtk *ssusb)
{
        mtu3_setbits(ssusb->mac_base, U3D_DEVICE_CONTROL, DC_SESSION);
        mtu3_setbits(ssusb->mac_base, U3D_POWER_MANAGEMENT, SOFT_CONN);
}

/* only port0 supports dual-role mode */
static int ssusb_port0_switch(struct ssusb_mtk *ssusb,
        int version, bool tohost)
{
        void __iomem *ibase = ssusb->ippc_base;
        u32 value;

        dev_dbg(ssusb->dev, "%s (switch u%d port0 to %s)\n", __func__,
                version, tohost ? "host" : "device");

        if (version == USB2_PORT) {
                /* 1. power off and disable u2 port0 */
                value = mtu3_readl(ibase, SSUSB_U2_CTRL(0));
                value |= SSUSB_U2_PORT_PDN | SSUSB_U2_PORT_DIS;
                mtu3_writel(ibase, SSUSB_U2_CTRL(0), value);

                /* 2. power on, enable u2 port0 and select its mode */
                value = mtu3_readl(ibase, SSUSB_U2_CTRL(0));
                value &= ~(SSUSB_U2_PORT_PDN | SSUSB_U2_PORT_DIS);
                value = tohost ? (value | SSUSB_U2_PORT_HOST_SEL) :
                        (value & (~SSUSB_U2_PORT_HOST_SEL));
                mtu3_writel(ibase, SSUSB_U2_CTRL(0), value);
        } else {
                /* 1. power off and disable u3 port0 */
                value = mtu3_readl(ibase, SSUSB_U3_CTRL(0));
                value |= SSUSB_U3_PORT_PDN | SSUSB_U3_PORT_DIS;
                mtu3_writel(ibase, SSUSB_U3_CTRL(0), value);

                /* 2. power on, enable u3 port0 and select its mode */
                value = mtu3_readl(ibase, SSUSB_U3_CTRL(0));
                value &= ~(SSUSB_U3_PORT_PDN | SSUSB_U3_PORT_DIS);
                value = tohost ? (value | SSUSB_U3_PORT_HOST_SEL) :
                        (value & (~SSUSB_U3_PORT_HOST_SEL));
                mtu3_writel(ibase, SSUSB_U3_CTRL(0), value);
        }

        return 0;
}

static void switch_port_to_host(struct ssusb_mtk *ssusb)
{
        u32 check_clk = 0;

        dev_dbg(ssusb->dev, "%s\n", __func__);

        ssusb_port0_switch(ssusb, USB2_PORT, true);

        if (ssusb->otg_switch.is_u3_drd) {
                ssusb_port0_switch(ssusb, USB3_PORT, true);
                check_clk = SSUSB_U3_MAC_RST_B_STS;
        }

        ssusb_check_clocks(ssusb, check_clk);

        /* after all clocks are stable */
        toggle_opstate(ssusb);
}

static void switch_port_to_device(struct ssusb_mtk *ssusb)
{
        u32 check_clk = 0;

        dev_dbg(ssusb->dev, "%s\n", __func__);

        ssusb_port0_switch(ssusb, USB2_PORT, false);

        if (ssusb->otg_switch.is_u3_drd) {
                ssusb_port0_switch(ssusb, USB3_PORT, false);
                check_clk = SSUSB_U3_MAC_RST_B_STS;
        }

        ssusb_check_clocks(ssusb, check_clk);
}

int ssusb_set_vbus(struct otg_switch_mtk *otg_sx, int is_on)
{
        struct ssusb_mtk *ssusb = otg_sx_to_ssusb(otg_sx);
        struct regulator *vbus = otg_sx->vbus;
        int ret;

        /* vbus is optional */
        if (!vbus)
                return 0;

        dev_dbg(ssusb->dev, "%s: turn %s\n", __func__, str_on_off(is_on));

        if (is_on) {
                ret = regulator_enable(vbus);
                if (ret) {
                        dev_err(ssusb->dev, "vbus regulator enable failed\n");
                        return ret;
                }
        } else {
                regulator_disable(vbus);
        }

        return 0;
}

static void ssusb_mode_sw_work(struct work_struct *work)
{
        struct otg_switch_mtk *otg_sx =
                container_of(work, struct otg_switch_mtk, dr_work);
        struct ssusb_mtk *ssusb = otg_sx_to_ssusb(otg_sx);
        struct mtu3 *mtu = ssusb->u3d;
        enum usb_role desired_role = otg_sx->desired_role;
        enum usb_role current_role;

        current_role = ssusb->is_host ? USB_ROLE_HOST : USB_ROLE_DEVICE;

        if (desired_role == USB_ROLE_NONE) {
                /* the default mode is host as probe does */
                desired_role = USB_ROLE_HOST;
                if (otg_sx->default_role == USB_ROLE_DEVICE)
                        desired_role = USB_ROLE_DEVICE;
        }

        if (current_role == desired_role)
                return;

        dev_dbg(ssusb->dev, "set role : %s\n", usb_role_string(desired_role));
        mtu3_dbg_trace(ssusb->dev, "set role : %s", usb_role_string(desired_role));
        pm_runtime_get_sync(ssusb->dev);

        switch (desired_role) {
        case USB_ROLE_HOST:
                ssusb_set_force_mode(ssusb, MTU3_DR_FORCE_HOST);
                mtu3_stop(mtu);
                switch_port_to_host(ssusb);
                ssusb_set_vbus(otg_sx, 1);
                ssusb->is_host = true;
                break;
        case USB_ROLE_DEVICE:
                ssusb_set_force_mode(ssusb, MTU3_DR_FORCE_DEVICE);
                ssusb->is_host = false;
                ssusb_set_vbus(otg_sx, 0);
                switch_port_to_device(ssusb);
                mtu3_start(mtu);
                break;
        case USB_ROLE_NONE:
        default:
                dev_err(ssusb->dev, "invalid role\n");
        }
        pm_runtime_put(ssusb->dev);
}

static void ssusb_set_mode(struct otg_switch_mtk *otg_sx, enum usb_role role)
{
        struct ssusb_mtk *ssusb = otg_sx_to_ssusb(otg_sx);

        if (ssusb->dr_mode != USB_DR_MODE_OTG)
                return;

        otg_sx->desired_role = role;
        queue_work(system_freezable_wq, &otg_sx->dr_work);
}

static int ssusb_id_notifier(struct notifier_block *nb,
        unsigned long event, void *ptr)
{
        struct otg_switch_mtk *otg_sx =
                container_of(nb, struct otg_switch_mtk, id_nb);

        ssusb_set_mode(otg_sx, event ? USB_ROLE_HOST : USB_ROLE_DEVICE);

        return NOTIFY_DONE;
}

static int ssusb_extcon_register(struct otg_switch_mtk *otg_sx)
{
        struct ssusb_mtk *ssusb = otg_sx_to_ssusb(otg_sx);
        struct extcon_dev *edev = otg_sx->edev;
        int ret;

        /* extcon is optional */
        if (!edev)
                return 0;

        otg_sx->id_nb.notifier_call = ssusb_id_notifier;
        ret = devm_extcon_register_notifier(ssusb->dev, edev, EXTCON_USB_HOST,
                                        &otg_sx->id_nb);
        if (ret < 0) {
                dev_err(ssusb->dev, "failed to register notifier for USB-HOST\n");
                return ret;
        }

        ret = extcon_get_state(edev, EXTCON_USB_HOST);
        dev_dbg(ssusb->dev, "EXTCON_USB_HOST: %d\n", ret);

        /* default as host, switch to device mode if needed */
        if (!ret)
                ssusb_set_mode(otg_sx, USB_ROLE_DEVICE);

        return 0;
}

/*
 * We provide an interface via debugfs to switch between host and device modes
 * depending on user input.
 * This is useful in special cases, such as uses TYPE-A receptacle but also
 * wants to support dual-role mode.
 */
void ssusb_mode_switch(struct ssusb_mtk *ssusb, int to_host)
{
        struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;

        ssusb_set_mode(otg_sx, to_host ? USB_ROLE_HOST : USB_ROLE_DEVICE);
}

void ssusb_set_force_mode(struct ssusb_mtk *ssusb,
                          enum mtu3_dr_force_mode mode)
{
        u32 value;

        value = mtu3_readl(ssusb->ippc_base, SSUSB_U2_CTRL(0));
        switch (mode) {
        case MTU3_DR_FORCE_DEVICE:
                value |= SSUSB_U2_PORT_FORCE_IDDIG | SSUSB_U2_PORT_RG_IDDIG;
                break;
        case MTU3_DR_FORCE_HOST:
                value |= SSUSB_U2_PORT_FORCE_IDDIG;
                value &= ~SSUSB_U2_PORT_RG_IDDIG;
                break;
        case MTU3_DR_FORCE_NONE:
                value &= ~(SSUSB_U2_PORT_FORCE_IDDIG | SSUSB_U2_PORT_RG_IDDIG);
                break;
        default:
                return;
        }
        mtu3_writel(ssusb->ippc_base, SSUSB_U2_CTRL(0), value);
}

static int ssusb_role_sw_set(struct usb_role_switch *sw, enum usb_role role)
{
        struct ssusb_mtk *ssusb = usb_role_switch_get_drvdata(sw);
        struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;

        ssusb_set_mode(otg_sx, role);

        return 0;
}

static enum usb_role ssusb_role_sw_get(struct usb_role_switch *sw)
{
        struct ssusb_mtk *ssusb = usb_role_switch_get_drvdata(sw);

        return ssusb->is_host ? USB_ROLE_HOST : USB_ROLE_DEVICE;
}

static int ssusb_role_sw_register(struct otg_switch_mtk *otg_sx)
{
        struct usb_role_switch_desc role_sx_desc = { 0 };
        struct ssusb_mtk *ssusb = otg_sx_to_ssusb(otg_sx);
        struct device *dev = ssusb->dev;
        enum usb_dr_mode mode;

        if (!otg_sx->role_sw_used)
                return 0;

        mode = usb_get_role_switch_default_mode(dev);
        if (mode == USB_DR_MODE_PERIPHERAL)
                otg_sx->default_role = USB_ROLE_DEVICE;
        else
                otg_sx->default_role = USB_ROLE_HOST;

        role_sx_desc.set = ssusb_role_sw_set;
        role_sx_desc.get = ssusb_role_sw_get;
        role_sx_desc.fwnode = dev_fwnode(dev);
        role_sx_desc.driver_data = ssusb;
        role_sx_desc.allow_userspace_control = true;
        otg_sx->role_sw = usb_role_switch_register(dev, &role_sx_desc);
        if (IS_ERR(otg_sx->role_sw))
                return PTR_ERR(otg_sx->role_sw);

        ssusb_set_mode(otg_sx, otg_sx->default_role);

        return 0;
}

int ssusb_otg_switch_init(struct ssusb_mtk *ssusb)
{
        struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;
        int ret = 0;

        INIT_WORK(&otg_sx->dr_work, ssusb_mode_sw_work);

        if (otg_sx->manual_drd_enabled)
                ssusb_dr_debugfs_init(ssusb);
        else if (otg_sx->role_sw_used)
                ret = ssusb_role_sw_register(otg_sx);
        else
                ret = ssusb_extcon_register(otg_sx);

        return ret;
}

void ssusb_otg_switch_exit(struct ssusb_mtk *ssusb)
{
        struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;

        cancel_work_sync(&otg_sx->dr_work);
        usb_role_switch_unregister(otg_sx->role_sw);
}