/**
 * ep0.c - DesignWare USB3 DRD Controller Endpoint 0 Handling
 *
 * Copyright (C) 2010-2011 Texas Instruments Incorporated - http://www.ti.com
 *
 * Authors: Felipe Balbi <balbi@ti.com>,
 *          Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2  of
 * the License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/list.h>
#include <linux/dma-mapping.h>

#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/usb/composite.h>

#include "core.h"
#include "debug.h"
#include "gadget.h"
#include "io.h"

static void __dwc3_ep0_do_control_status(struct dwc3 *dwc, struct dwc3_ep *dep);
static void __dwc3_ep0_do_control_data(struct dwc3 *dwc,
                struct dwc3_ep *dep, struct dwc3_request *req);

static const char *dwc3_ep0_state_string(enum dwc3_ep0_state state)
{
        switch (state) {
        case EP0_UNCONNECTED:
                return "Unconnected";
        case EP0_SETUP_PHASE:
                return "Setup Phase";
        case EP0_DATA_PHASE:
                return "Data Phase";
        case EP0_STATUS_PHASE:
                return "Status Phase";
        default:
                return "UNKNOWN";
        }
}

static int dwc3_ep0_start_trans(struct dwc3 *dwc, u8 epnum, dma_addr_t buf_dma,
                u32 len, u32 type, bool chain)
{
        struct dwc3_gadget_ep_cmd_params params;
        struct dwc3_trb                 *trb;
        struct dwc3_ep                  *dep;

        int                             ret;

        dep = dwc->eps[epnum];
        if (dep->flags & DWC3_EP_BUSY) {
                dwc3_trace(trace_dwc3_ep0, "%s still busy", dep->name);
                return 0;
        }

        trb = &dwc->ep0_trb[dep->trb_enqueue];

        if (chain)
                dep->trb_enqueue++;

        trb->bpl = lower_32_bits(buf_dma);
        trb->bph = upper_32_bits(buf_dma);
        trb->size = len;
        trb->ctrl = type;

        trb->ctrl |= (DWC3_TRB_CTRL_HWO
                        | DWC3_TRB_CTRL_ISP_IMI);

        if (chain)
                trb->ctrl |= DWC3_TRB_CTRL_CHN;
        else
                trb->ctrl |= (DWC3_TRB_CTRL_IOC
                                | DWC3_TRB_CTRL_LST);

        if (chain)
                return 0;

        memset(&params, 0, sizeof(params));
        params.param0 = upper_32_bits(dwc->ep0_trb_addr);
        params.param1 = lower_32_bits(dwc->ep0_trb_addr);

        trace_dwc3_prepare_trb(dep, trb);

        ret = dwc3_send_gadget_ep_cmd(dwc, dep->number,
                        DWC3_DEPCMD_STARTTRANSFER, &params);
        if (ret < 0) {
                dwc3_trace(trace_dwc3_ep0, "%s STARTTRANSFER failed",
                                dep->name);
                return ret;
        }

        dep->flags |= DWC3_EP_BUSY;
        dep->resource_index = dwc3_gadget_ep_get_transfer_index(dwc,
                        dep->number);

        dwc->ep0_next_event = DWC3_EP0_COMPLETE;

        return 0;
}

static int __dwc3_gadget_ep0_queue(struct dwc3_ep *dep,
                struct dwc3_request *req)
{
        struct dwc3             *dwc = dep->dwc;

        req->request.actual     = 0;
        req->request.status     = -EINPROGRESS;
        req->epnum              = dep->number;

        list_add_tail(&req->list, &dep->pending_list);

        /*
         * Gadget driver might not be quick enough to queue a request
         * before we get a Transfer Not Ready event on this endpoint.
         *
         * In that case, we will set DWC3_EP_PENDING_REQUEST. When that
         * flag is set, it's telling us that as soon as Gadget queues the
         * required request, we should kick the transfer here because the
         * IRQ we were waiting for is long gone.
         */
        if (dep->flags & DWC3_EP_PENDING_REQUEST) {
                unsigned        direction;

                direction = !!(dep->flags & DWC3_EP0_DIR_IN);

                if (dwc->ep0state != EP0_DATA_PHASE) {
                        dev_WARN(dwc->dev, "Unexpected pending request\n");
                        return 0;
                }

                __dwc3_ep0_do_control_data(dwc, dwc->eps[direction], req);

                dep->flags &= ~(DWC3_EP_PENDING_REQUEST |
                                DWC3_EP0_DIR_IN);

                return 0;
        }

        /*
         * In case gadget driver asked us to delay the STATUS phase,
         * handle it here.
         */
        if (dwc->delayed_status) {
                unsigned        direction;

                direction = !dwc->ep0_expect_in;
                dwc->delayed_status = false;
                usb_gadget_set_state(&dwc->gadget, USB_STATE_CONFIGURED);

                if (dwc->ep0state == EP0_STATUS_PHASE)
                        __dwc3_ep0_do_control_status(dwc, dwc->eps[direction]);
                else
                        dwc3_trace(trace_dwc3_ep0,
                                        "too early for delayed status");

                return 0;
        }

        /*
         * Unfortunately we have uncovered a limitation wrt the Data Phase.
         *
         * Section 9.4 says we can wait for the XferNotReady(DATA) event to
         * come before issueing Start Transfer command, but if we do, we will
         * miss situations where the host starts another SETUP phase instead of
         * the DATA phase.  Such cases happen at least on TD.7.6 of the Link
         * Layer Compliance Suite.
         *
         * The problem surfaces due to the fact that in case of back-to-back
         * SETUP packets there will be no XferNotReady(DATA) generated and we
         * will be stuck waiting for XferNotReady(DATA) forever.
         *
         * By looking at tables 9-13 and 9-14 of the Databook, we can see that
         * it tells us to start Data Phase right away. It also mentions that if
         * we receive a SETUP phase instead of the DATA phase, core will issue
         * XferComplete for the DATA phase, before actually initiating it in
         * the wire, with the TRB's status set to "SETUP_PENDING". Such status
         * can only be used to print some debugging logs, as the core expects
         * us to go through to the STATUS phase and start a CONTROL_STATUS TRB,
         * just so it completes right away, without transferring anything and,
         * only then, we can go back to the SETUP phase.
         *
         * Because of this scenario, SNPS decided to change the programming
         * model of control transfers and support on-demand transfers only for
         * the STATUS phase. To fix the issue we have now, we will always wait
         * for gadget driver to queue the DATA phase's struct usb_request, then
         * start it right away.
         *
         * If we're actually in a 2-stage transfer, we will wait for
         * XferNotReady(STATUS).
         */
        if (dwc->three_stage_setup) {
                unsigned        direction;

                direction = dwc->ep0_expect_in;
                dwc->ep0state = EP0_DATA_PHASE;

                __dwc3_ep0_do_control_data(dwc, dwc->eps[direction], req);

                dep->flags &= ~DWC3_EP0_DIR_IN;
        }

        return 0;
}

int dwc3_gadget_ep0_queue(struct usb_ep *ep, struct usb_request *request,
                gfp_t gfp_flags)
{
        struct dwc3_request             *req = to_dwc3_request(request);
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);
        struct dwc3                     *dwc = dep->dwc;

        unsigned long                   flags;

        int                             ret;

        spin_lock_irqsave(&dwc->lock, flags);
        if (!dep->endpoint.desc) {
                dwc3_trace(trace_dwc3_ep0,
                                "trying to queue request %p to disabled %s",
                                request, dep->name);
                ret = -ESHUTDOWN;
                goto out;
        }

        /* we share one TRB for ep0/1 */
        if (!list_empty(&dep->pending_list)) {
                ret = -EBUSY;
                goto out;
        }

        dwc3_trace(trace_dwc3_ep0,
                        "queueing request %p to %s length %d state '%s'",
                        request, dep->name, request->length,
                        dwc3_ep0_state_string(dwc->ep0state));

        ret = __dwc3_gadget_ep0_queue(dep, req);

out:
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static void dwc3_ep0_stall_and_restart(struct dwc3 *dwc)
{
        struct dwc3_ep          *dep;

        /* reinitialize physical ep1 */
        dep = dwc->eps[1];
        dep->flags = DWC3_EP_ENABLED;

        /* stall is always issued on EP0 */
        dep = dwc->eps[0];
        __dwc3_gadget_ep_set_halt(dep, 1, false);
        dep->flags = DWC3_EP_ENABLED;
        dwc->delayed_status = false;

        if (!list_empty(&dep->pending_list)) {
                struct dwc3_request     *req;

                req = next_request(&dep->pending_list);
                dwc3_gadget_giveback(dep, req, -ECONNRESET);
        }

        dwc->ep0state = EP0_SETUP_PHASE;
        dwc3_ep0_out_start(dwc);
}

int __dwc3_gadget_ep0_set_halt(struct usb_ep *ep, int value)
{
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);
        struct dwc3                     *dwc = dep->dwc;

        dwc3_ep0_stall_and_restart(dwc);

        return 0;
}

int dwc3_gadget_ep0_set_halt(struct usb_ep *ep, int value)
{
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);
        struct dwc3                     *dwc = dep->dwc;
        unsigned long                   flags;
        int                             ret;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = __dwc3_gadget_ep0_set_halt(ep, value);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

void dwc3_ep0_out_start(struct dwc3 *dwc)
{
        int                             ret;

        ret = dwc3_ep0_start_trans(dwc, 0, dwc->ctrl_req_addr, 8,
                        DWC3_TRBCTL_CONTROL_SETUP, false);
        WARN_ON(ret < 0);
}

static struct dwc3_ep *dwc3_wIndex_to_dep(struct dwc3 *dwc, __le16 wIndex_le)
{
        struct dwc3_ep          *dep;
        u32                     windex = le16_to_cpu(wIndex_le);
        u32                     epnum;

        epnum = (windex & USB_ENDPOINT_NUMBER_MASK) << 1;
        if ((windex & USB_ENDPOINT_DIR_MASK) == USB_DIR_IN)
                epnum |= 1;

        dep = dwc->eps[epnum];
        if (dep->flags & DWC3_EP_ENABLED)
                return dep;

        return NULL;
}

static void dwc3_ep0_status_cmpl(struct usb_ep *ep, struct usb_request *req)
{
}
/*
 * ch 9.4.5
 */
static int dwc3_ep0_handle_status(struct dwc3 *dwc,
                struct usb_ctrlrequest *ctrl)
{
        struct dwc3_ep          *dep;
        u32                     recip;
        u32                     reg;
        u16                     usb_status = 0;
        __le16                  *response_pkt;

        recip = ctrl->bRequestType & USB_RECIP_MASK;
        switch (recip) {
        case USB_RECIP_DEVICE:
                /*
                 * LTM will be set once we know how to set this in HW.
                 */
                usb_status |= dwc->gadget.is_selfpowered;

                if ((dwc->speed == DWC3_DSTS_SUPERSPEED) ||
                    (dwc->speed == DWC3_DSTS_SUPERSPEED_PLUS)) {
                        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                        if (reg & DWC3_DCTL_INITU1ENA)
                                usb_status |= 1 << USB_DEV_STAT_U1_ENABLED;
                        if (reg & DWC3_DCTL_INITU2ENA)
                                usb_status |= 1 << USB_DEV_STAT_U2_ENABLED;
                }

                break;

        case USB_RECIP_INTERFACE:
                /*
                 * Function Remote Wake Capable D0
                 * Function Remote Wakeup       D1
                 */
                break;

        case USB_RECIP_ENDPOINT:
                dep = dwc3_wIndex_to_dep(dwc, ctrl->wIndex);
                if (!dep)
                        return -EINVAL;

                if (dep->flags & DWC3_EP_STALL)
                        usb_status = 1 << USB_ENDPOINT_HALT;
                break;
        default:
                return -EINVAL;
        }

        response_pkt = (__le16 *) dwc->setup_buf;
        *response_pkt = cpu_to_le16(usb_status);

        dep = dwc->eps[0];
        dwc->ep0_usb_req.dep = dep;
        dwc->ep0_usb_req.request.length = sizeof(*response_pkt);
        dwc->ep0_usb_req.request.buf = dwc->setup_buf;
        dwc->ep0_usb_req.request.complete = dwc3_ep0_status_cmpl;

        return __dwc3_gadget_ep0_queue(dep, &dwc->ep0_usb_req);
}

static int dwc3_ep0_handle_feature(struct dwc3 *dwc,
                struct usb_ctrlrequest *ctrl, int set)
{
        struct dwc3_ep          *dep;
        u32                     recip;
        u32                     wValue;
        u32                     wIndex;
        u32                     reg;
        int                     ret;
        enum usb_device_state   state;

        wValue = le16_to_cpu(ctrl->wValue);
        wIndex = le16_to_cpu(ctrl->wIndex);
        recip = ctrl->bRequestType & USB_RECIP_MASK;
        state = dwc->gadget.state;

        switch (recip) {
        case USB_RECIP_DEVICE:

                switch (wValue) {
                case USB_DEVICE_REMOTE_WAKEUP:
                        break;
                /*
                 * 9.4.1 says only only for SS, in AddressState only for
                 * default control pipe
                 */
                case USB_DEVICE_U1_ENABLE:
                        if (state != USB_STATE_CONFIGURED)
                                return -EINVAL;
                        if ((dwc->speed != DWC3_DSTS_SUPERSPEED) &&
                            (dwc->speed != DWC3_DSTS_SUPERSPEED_PLUS))
                                return -EINVAL;

                        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                        if (set)
                                reg |= DWC3_DCTL_INITU1ENA;
                        else
                                reg &= ~DWC3_DCTL_INITU1ENA;
                        dwc3_writel(dwc->regs, DWC3_DCTL, reg);
                        break;

                case USB_DEVICE_U2_ENABLE:
                        if (state != USB_STATE_CONFIGURED)
                                return -EINVAL;
                        if ((dwc->speed != DWC3_DSTS_SUPERSPEED) &&
                            (dwc->speed != DWC3_DSTS_SUPERSPEED_PLUS))
                                return -EINVAL;

                        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                        if (set)
                                reg |= DWC3_DCTL_INITU2ENA;
                        else
                                reg &= ~DWC3_DCTL_INITU2ENA;
                        dwc3_writel(dwc->regs, DWC3_DCTL, reg);
                        break;

                case USB_DEVICE_LTM_ENABLE:
                        return -EINVAL;

                case USB_DEVICE_TEST_MODE:
                        if ((wIndex & 0xff) != 0)
                                return -EINVAL;
                        if (!set)
                                return -EINVAL;

                        switch (wIndex >> 8) {
                        case TEST_J:
                        case TEST_K:
                        case TEST_SE0_NAK:
                        case TEST_PACKET:
                        case TEST_FORCE_EN:
                                dwc->test_mode_nr = wIndex >> 8;
                                dwc->test_mode = true;
                                break;
                        default:
                                return -EINVAL;
                        }
                        break;
                default:
                        return -EINVAL;
                }
                break;

        case USB_RECIP_INTERFACE:
                switch (wValue) {
                case USB_INTRF_FUNC_SUSPEND:
                        if (wIndex & USB_INTRF_FUNC_SUSPEND_LP)
                                /* XXX enable Low power suspend */
                                ;
                        if (wIndex & USB_INTRF_FUNC_SUSPEND_RW)
                                /* XXX enable remote wakeup */
                                ;
                        break;
                default:
                        return -EINVAL;
                }
                break;

        case USB_RECIP_ENDPOINT:
                switch (wValue) {
                case USB_ENDPOINT_HALT:
                        dep = dwc3_wIndex_to_dep(dwc, wIndex);
                        if (!dep)
                                return -EINVAL;
                        if (set == 0 && (dep->flags & DWC3_EP_WEDGE))
                                break;
                        ret = __dwc3_gadget_ep_set_halt(dep, set, true);
                        if (ret)
                                return -EINVAL;
                        break;
                default:
                        return -EINVAL;
                }
                break;

        default:
                return -EINVAL;
        }

        return 0;
}

static int dwc3_ep0_set_address(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
{
        enum usb_device_state state = dwc->gadget.state;
        u32 addr;
        u32 reg;

        addr = le16_to_cpu(ctrl->wValue);
        if (addr > 127) {
                dwc3_trace(trace_dwc3_ep0, "invalid device address %d", addr);
                return -EINVAL;
        }

        if (state == USB_STATE_CONFIGURED) {
                dwc3_trace(trace_dwc3_ep0,
                                "trying to set address when configured");
                return -EINVAL;
        }

        reg = dwc3_readl(dwc->regs, DWC3_DCFG);
        reg &= ~(DWC3_DCFG_DEVADDR_MASK);
        reg |= DWC3_DCFG_DEVADDR(addr);
        dwc3_writel(dwc->regs, DWC3_DCFG, reg);

        if (addr)
                usb_gadget_set_state(&dwc->gadget, USB_STATE_ADDRESS);
        else
                usb_gadget_set_state(&dwc->gadget, USB_STATE_DEFAULT);

        return 0;
}

static int dwc3_ep0_delegate_req(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
{
        int ret;

        spin_unlock(&dwc->lock);
        ret = dwc->gadget_driver->setup(&dwc->gadget, ctrl);
        spin_lock(&dwc->lock);
        return ret;
}

static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
{
        enum usb_device_state state = dwc->gadget.state;
        u32 cfg;
        int ret;
        u32 reg;

        cfg = le16_to_cpu(ctrl->wValue);

        switch (state) {
        case USB_STATE_DEFAULT:
                return -EINVAL;

        case USB_STATE_ADDRESS:
                ret = dwc3_ep0_delegate_req(dwc, ctrl);
                /* if the cfg matches and the cfg is non zero */
                if (cfg && (!ret || (ret == USB_GADGET_DELAYED_STATUS))) {

                        /*
                         * only change state if set_config has already
                         * been processed. If gadget driver returns
                         * USB_GADGET_DELAYED_STATUS, we will wait
                         * to change the state on the next usb_ep_queue()
                         */
                        if (ret == 0)
                                usb_gadget_set_state(&dwc->gadget,
                                                USB_STATE_CONFIGURED);

                        /*
                         * Enable transition to U1/U2 state when
                         * nothing is pending from application.
                         */
                        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                        reg |= (DWC3_DCTL_ACCEPTU1ENA | DWC3_DCTL_ACCEPTU2ENA);
                        dwc3_writel(dwc->regs, DWC3_DCTL, reg);
                }
                break;

        case USB_STATE_CONFIGURED:
                ret = dwc3_ep0_delegate_req(dwc, ctrl);
                if (!cfg && !ret)
                        usb_gadget_set_state(&dwc->gadget,
                                        USB_STATE_ADDRESS);
                break;
        default:
                ret = -EINVAL;
        }
        return ret;
}

static void dwc3_ep0_set_sel_cmpl(struct usb_ep *ep, struct usb_request *req)
{
        struct dwc3_ep  *dep = to_dwc3_ep(ep);
        struct dwc3     *dwc = dep->dwc;

        u32             param = 0;
        u32             reg;

        struct timing {
                u8      u1sel;
                u8      u1pel;
                u16     u2sel;
                u16     u2pel;
        } __packed timing;

        int             ret;

        memcpy(&timing, req->buf, sizeof(timing));

        dwc->u1sel = timing.u1sel;
        dwc->u1pel = timing.u1pel;
        dwc->u2sel = le16_to_cpu(timing.u2sel);
        dwc->u2pel = le16_to_cpu(timing.u2pel);

        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
        if (reg & DWC3_DCTL_INITU2ENA)
                param = dwc->u2pel;
        if (reg & DWC3_DCTL_INITU1ENA)
                param = dwc->u1pel;

        /*
         * According to Synopsys Databook, if parameter is
         * greater than 125, a value of zero should be
         * programmed in the register.
         */
        if (param > 125)
                param = 0;

        /* now that we have the time, issue DGCMD Set Sel */
        ret = dwc3_send_gadget_generic_command(dwc,
                        DWC3_DGCMD_SET_PERIODIC_PAR, param);
        WARN_ON(ret < 0);
}

static int dwc3_ep0_set_sel(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
{
        struct dwc3_ep  *dep;
        enum usb_device_state state = dwc->gadget.state;
        u16             wLength;
        u16             wValue;

        if (state == USB_STATE_DEFAULT)
                return -EINVAL;

        wValue = le16_to_cpu(ctrl->wValue);
        wLength = le16_to_cpu(ctrl->wLength);

        if (wLength != 6) {
                dev_err(dwc->dev, "Set SEL should be 6 bytes, got %d\n",
                                wLength);
                return -EINVAL;
        }

        /*
         * To handle Set SEL we need to receive 6 bytes from Host. So let's
         * queue a usb_request for 6 bytes.
         *
         * Remember, though, this controller can't handle non-wMaxPacketSize
         * aligned transfers on the OUT direction, so we queue a request for
         * wMaxPacketSize instead.
         */
        dep = dwc->eps[0];
        dwc->ep0_usb_req.dep = dep;
        dwc->ep0_usb_req.request.length = dep->endpoint.maxpacket;
        dwc->ep0_usb_req.request.buf = dwc->setup_buf;
        dwc->ep0_usb_req.request.complete = dwc3_ep0_set_sel_cmpl;

        return __dwc3_gadget_ep0_queue(dep, &dwc->ep0_usb_req);
}

static int dwc3_ep0_set_isoch_delay(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
{
        u16             wLength;
        u16             wValue;
        u16             wIndex;

        wValue = le16_to_cpu(ctrl->wValue);
        wLength = le16_to_cpu(ctrl->wLength);
        wIndex = le16_to_cpu(ctrl->wIndex);

        if (wIndex || wLength)
                return -EINVAL;

        /*
         * REVISIT It's unclear from Databook what to do with this
         * value. For now, just cache it.
         */
        dwc->isoch_delay = wValue;

        return 0;
}

static int dwc3_ep0_std_request(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
{
        int ret;

        switch (ctrl->bRequest) {
        case USB_REQ_GET_STATUS:
                dwc3_trace(trace_dwc3_ep0, "USB_REQ_GET_STATUS");
                ret = dwc3_ep0_handle_status(dwc, ctrl);
                break;
        case USB_REQ_CLEAR_FEATURE:
                dwc3_trace(trace_dwc3_ep0, "USB_REQ_CLEAR_FEATURE");
                ret = dwc3_ep0_handle_feature(dwc, ctrl, 0);
                break;
        case USB_REQ_SET_FEATURE:
                dwc3_trace(trace_dwc3_ep0, "USB_REQ_SET_FEATURE");
                ret = dwc3_ep0_handle_feature(dwc, ctrl, 1);
                break;
        case USB_REQ_SET_ADDRESS:
                dwc3_trace(trace_dwc3_ep0, "USB_REQ_SET_ADDRESS");
                ret = dwc3_ep0_set_address(dwc, ctrl);
                break;
        case USB_REQ_SET_CONFIGURATION:
                dwc3_trace(trace_dwc3_ep0, "USB_REQ_SET_CONFIGURATION");
                ret = dwc3_ep0_set_config(dwc, ctrl);
                break;
        case USB_REQ_SET_SEL:
                dwc3_trace(trace_dwc3_ep0, "USB_REQ_SET_SEL");
                ret = dwc3_ep0_set_sel(dwc, ctrl);
                break;
        case USB_REQ_SET_ISOCH_DELAY:
                dwc3_trace(trace_dwc3_ep0, "USB_REQ_SET_ISOCH_DELAY");
                ret = dwc3_ep0_set_isoch_delay(dwc, ctrl);
                break;
        default:
                dwc3_trace(trace_dwc3_ep0, "Forwarding to gadget driver");
                ret = dwc3_ep0_delegate_req(dwc, ctrl);
                break;
        }

        return ret;
}

static void dwc3_ep0_inspect_setup(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        struct usb_ctrlrequest *ctrl = dwc->ctrl_req;
        int ret = -EINVAL;
        u32 len;

        if (!dwc->gadget_driver)
                goto out;

        trace_dwc3_ctrl_req(ctrl);

        len = le16_to_cpu(ctrl->wLength);
        if (!len) {
                dwc->three_stage_setup = false;
                dwc->ep0_expect_in = false;
                dwc->ep0_next_event = DWC3_EP0_NRDY_STATUS;
        } else {
                dwc->three_stage_setup = true;
                dwc->ep0_expect_in = !!(ctrl->bRequestType & USB_DIR_IN);
                dwc->ep0_next_event = DWC3_EP0_NRDY_DATA;
        }

        if ((ctrl->bRequestType & USB_TYPE_MASK) == USB_TYPE_STANDARD)
                ret = dwc3_ep0_std_request(dwc, ctrl);
        else
                ret = dwc3_ep0_delegate_req(dwc, ctrl);

        if (ret == USB_GADGET_DELAYED_STATUS)
                dwc->delayed_status = true;

out:
        if (ret < 0)
                dwc3_ep0_stall_and_restart(dwc);
}

static void dwc3_ep0_complete_data(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        struct dwc3_request     *r = NULL;
        struct usb_request      *ur;
        struct dwc3_trb         *trb;
        struct dwc3_ep          *ep0;
        unsigned                transfer_size = 0;
        unsigned                maxp;
        unsigned                remaining_ur_length;
        void                    *buf;
        u32                     transferred = 0;
        u32                     status;
        u32                     length;
        u8                      epnum;

        epnum = event->endpoint_number;
        ep0 = dwc->eps[0];

        dwc->ep0_next_event = DWC3_EP0_NRDY_STATUS;

        trb = dwc->ep0_trb;

        trace_dwc3_complete_trb(ep0, trb);

        r = next_request(&ep0->pending_list);
        if (!r)
                return;

        status = DWC3_TRB_SIZE_TRBSTS(trb->size);
        if (status == DWC3_TRBSTS_SETUP_PENDING) {
                dwc->setup_packet_pending = true;

                dwc3_trace(trace_dwc3_ep0, "Setup Pending received");

                if (r)
                        dwc3_gadget_giveback(ep0, r, -ECONNRESET);

                return;
        }

        ur = &r->request;
        buf = ur->buf;
        remaining_ur_length = ur->length;

        length = trb->size & DWC3_TRB_SIZE_MASK;

        maxp = ep0->endpoint.maxpacket;

        if (dwc->ep0_bounced) {
                /*
                 * Handle the first TRB before handling the bounce buffer if
                 * the request length is greater than the bounce buffer size
                 */
                if (ur->length > DWC3_EP0_BOUNCE_SIZE) {
                        transfer_size = ALIGN(ur->length - maxp, maxp);
                        transferred = transfer_size - length;
                        buf = (u8 *)buf + transferred;
                        ur->actual += transferred;
                        remaining_ur_length -= transferred;

                        trb++;
                        length = trb->size & DWC3_TRB_SIZE_MASK;

                        ep0->trb_enqueue = 0;
                }

                transfer_size = roundup((ur->length - transfer_size),
                                        maxp);

                transferred = min_t(u32, remaining_ur_length,
                                    transfer_size - length);
                memcpy(buf, dwc->ep0_bounce, transferred);
        } else {
                transferred = ur->length - length;
        }

        ur->actual += transferred;

        if ((epnum & 1) && ur->actual < ur->length) {
                /* for some reason we did not get everything out */

                dwc3_ep0_stall_and_restart(dwc);
        } else {
                dwc3_gadget_giveback(ep0, r, 0);

                if (IS_ALIGNED(ur->length, ep0->endpoint.maxpacket) &&
                                ur->length && ur->zero) {
                        int ret;

                        dwc->ep0_next_event = DWC3_EP0_COMPLETE;

                        ret = dwc3_ep0_start_trans(dwc, epnum,
                                        dwc->ctrl_req_addr, 0,
                                        DWC3_TRBCTL_CONTROL_DATA, false);
                        WARN_ON(ret < 0);
                }
        }
}

static void dwc3_ep0_complete_status(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        struct dwc3_request     *r;
        struct dwc3_ep          *dep;
        struct dwc3_trb         *trb;
        u32                     status;

        dep = dwc->eps[0];
        trb = dwc->ep0_trb;

        trace_dwc3_complete_trb(dep, trb);

        if (!list_empty(&dep->pending_list)) {
                r = next_request(&dep->pending_list);

                dwc3_gadget_giveback(dep, r, 0);
        }

        if (dwc->test_mode) {
                int ret;

                ret = dwc3_gadget_set_test_mode(dwc, dwc->test_mode_nr);
                if (ret < 0) {
                        dwc3_trace(trace_dwc3_ep0, "Invalid Test #%d",
                                        dwc->test_mode_nr);
                        dwc3_ep0_stall_and_restart(dwc);
                        return;
                }
        }

        status = DWC3_TRB_SIZE_TRBSTS(trb->size);
        if (status == DWC3_TRBSTS_SETUP_PENDING) {
                dwc->setup_packet_pending = true;
                dwc3_trace(trace_dwc3_ep0, "Setup Pending received");
        }

        dwc->ep0state = EP0_SETUP_PHASE;
        dwc3_ep0_out_start(dwc);
}

static void dwc3_ep0_xfer_complete(struct dwc3 *dwc,
                        const struct dwc3_event_depevt *event)
{
        struct dwc3_ep          *dep = dwc->eps[event->endpoint_number];

        dep->flags &= ~DWC3_EP_BUSY;
        dep->resource_index = 0;
        dwc->setup_packet_pending = false;

        switch (dwc->ep0state) {
        case EP0_SETUP_PHASE:
                dwc3_trace(trace_dwc3_ep0, "Setup Phase");
                dwc3_ep0_inspect_setup(dwc, event);
                break;

        case EP0_DATA_PHASE:
                dwc3_trace(trace_dwc3_ep0, "Data Phase");
                dwc3_ep0_complete_data(dwc, event);
                break;

        case EP0_STATUS_PHASE:
                dwc3_trace(trace_dwc3_ep0, "Status Phase");
                dwc3_ep0_complete_status(dwc, event);
                break;
        default:
                WARN(true, "UNKNOWN ep0state %d\n", dwc->ep0state);
        }
}

static void __dwc3_ep0_do_control_data(struct dwc3 *dwc,
                struct dwc3_ep *dep, struct dwc3_request *req)
{
        int                     ret;

        req->direction = !!dep->number;

        if (req->request.length == 0) {
                ret = dwc3_ep0_start_trans(dwc, dep->number,
                                dwc->ctrl_req_addr, 0,
                                DWC3_TRBCTL_CONTROL_DATA, false);
        } else if (!IS_ALIGNED(req->request.length, dep->endpoint.maxpacket)
                        && (dep->number == 0)) {
                u32     transfer_size = 0;
                u32     maxpacket;

                ret = usb_gadget_map_request(&dwc->gadget, &req->request,
                                dep->number);
                if (ret) {
                        dwc3_trace(trace_dwc3_ep0, "failed to map request\n");
                        return;
                }

                maxpacket = dep->endpoint.maxpacket;

                if (req->request.length > DWC3_EP0_BOUNCE_SIZE) {
                        transfer_size = ALIGN(req->request.length - maxpacket,
                                              maxpacket);
                        ret = dwc3_ep0_start_trans(dwc, dep->number,
                                                   req->request.dma,
                                                   transfer_size,
                                                   DWC3_TRBCTL_CONTROL_DATA,
                                                   true);
                }

                transfer_size = roundup((req->request.length - transfer_size),
                                        maxpacket);

                dwc->ep0_bounced = true;

                ret = dwc3_ep0_start_trans(dwc, dep->number,
                                dwc->ep0_bounce_addr, transfer_size,
                                DWC3_TRBCTL_CONTROL_DATA, false);
        } else {
                ret = usb_gadget_map_request(&dwc->gadget, &req->request,
                                dep->number);
                if (ret) {
                        dwc3_trace(trace_dwc3_ep0, "failed to map request\n");
                        return;
                }

                ret = dwc3_ep0_start_trans(dwc, dep->number, req->request.dma,
                                req->request.length, DWC3_TRBCTL_CONTROL_DATA,
                                false);
        }

        WARN_ON(ret < 0);
}

static int dwc3_ep0_start_control_status(struct dwc3_ep *dep)
{
        struct dwc3             *dwc = dep->dwc;
        u32                     type;

        type = dwc->three_stage_setup ? DWC3_TRBCTL_CONTROL_STATUS3
                : DWC3_TRBCTL_CONTROL_STATUS2;

        return dwc3_ep0_start_trans(dwc, dep->number,
                        dwc->ctrl_req_addr, 0, type, false);
}

static void __dwc3_ep0_do_control_status(struct dwc3 *dwc, struct dwc3_ep *dep)
{
        WARN_ON(dwc3_ep0_start_control_status(dep));
}

static void dwc3_ep0_do_control_status(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        struct dwc3_ep          *dep = dwc->eps[event->endpoint_number];

        __dwc3_ep0_do_control_status(dwc, dep);
}

static void dwc3_ep0_end_control_data(struct dwc3 *dwc, struct dwc3_ep *dep)
{
        struct dwc3_gadget_ep_cmd_params params;
        u32                     cmd;
        int                     ret;

        if (!dep->resource_index)
                return;

        cmd = DWC3_DEPCMD_ENDTRANSFER;
        cmd |= DWC3_DEPCMD_CMDIOC;
        cmd |= DWC3_DEPCMD_PARAM(dep->resource_index);
        memset(&params, 0, sizeof(params));
        ret = dwc3_send_gadget_ep_cmd(dwc, dep->number, cmd, &params);
        WARN_ON_ONCE(ret);
        dep->resource_index = 0;
}

static void dwc3_ep0_xfernotready(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        switch (event->status) {
        case DEPEVT_STATUS_CONTROL_DATA:
                dwc3_trace(trace_dwc3_ep0, "Control Data");

                /*
                 * We already have a DATA transfer in the controller's cache,
                 * if we receive a XferNotReady(DATA) we will ignore it, unless
                 * it's for the wrong direction.
                 *
                 * In that case, we must issue END_TRANSFER command to the Data
                 * Phase we already have started and issue SetStall on the
                 * control endpoint.
                 */
                if (dwc->ep0_expect_in != event->endpoint_number) {
                        struct dwc3_ep  *dep = dwc->eps[dwc->ep0_expect_in];

                        dwc3_trace(trace_dwc3_ep0,
                                        "Wrong direction for Data phase");
                        dwc3_ep0_end_control_data(dwc, dep);
                        dwc3_ep0_stall_and_restart(dwc);
                        return;
                }

                break;

        case DEPEVT_STATUS_CONTROL_STATUS:
                if (dwc->ep0_next_event != DWC3_EP0_NRDY_STATUS)
                        return;

                dwc3_trace(trace_dwc3_ep0, "Control Status");

                dwc->ep0state = EP0_STATUS_PHASE;

                if (dwc->delayed_status) {
                        WARN_ON_ONCE(event->endpoint_number != 1);
                        dwc3_trace(trace_dwc3_ep0, "Delayed Status");
                        return;
                }

                dwc3_ep0_do_control_status(dwc, event);
        }
}

void dwc3_ep0_interrupt(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        u8                      epnum = event->endpoint_number;

        dwc3_trace(trace_dwc3_ep0, "%s while ep%d%s in state '%s'",
                        dwc3_ep_event_string(event->endpoint_event),
                        epnum >> 1, (epnum & 1) ? "in" : "out",
                        dwc3_ep0_state_string(dwc->ep0state));

        switch (event->endpoint_event) {
        case DWC3_DEPEVT_XFERCOMPLETE:
                dwc3_ep0_xfer_complete(dwc, event);
                break;

        case DWC3_DEPEVT_XFERNOTREADY:
                dwc3_ep0_xfernotready(dwc, event);
                break;

        case DWC3_DEPEVT_XFERINPROGRESS:
        case DWC3_DEPEVT_RXTXFIFOEVT:
        case DWC3_DEPEVT_STREAMEVT:
        case DWC3_DEPEVT_EPCMDCMPLT:
                break;
        }
}