usb: dwc3: ep0: fix for possible early delayed_status

[linux/fpc-iii.git] / drivers / usb / dwc3 / ep0.c

/**
 * 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>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The names of the above-listed copyright holders may not be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * ALTERNATIVELY, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2, as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#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 "gadget.h"
#include "io.h"

static void dwc3_ep0_do_control_status(struct dwc3 *dwc, u32 epnum);

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)
{
        struct dwc3_gadget_ep_cmd_params params;
        struct dwc3_trb_hw              *trb_hw;
        struct dwc3_trb                 trb;
        struct dwc3_ep                  *dep;

        int                             ret;

        dep = dwc->eps[epnum];
        if (dep->flags & DWC3_EP_BUSY) {
                dev_vdbg(dwc->dev, "%s: still busy\n", dep->name);
                return 0;
        }

        trb_hw = dwc->ep0_trb;
        memset(&trb, 0, sizeof(trb));

        trb.trbctl = type;
        trb.bplh = buf_dma;
        trb.length = len;

        trb.hwo = 1;
        trb.lst = 1;
        trb.ioc = 1;
        trb.isp_imi = 1;

        dwc3_trb_to_hw(&trb, trb_hw);

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

        ret = dwc3_send_gadget_ep_cmd(dwc, dep->number,
                        DWC3_DEPCMD_STARTTRANSFER, &params);
        if (ret < 0) {
                dev_dbg(dwc->dev, "failed to send STARTTRANSFER command\n");
                return ret;
        }

        dep->flags |= DWC3_EP_BUSY;
        dep->res_trans_idx = 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;
        u32                     type;
        int                     ret = 0;

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

        list_add_tail(&req->list, &dep->request_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_STATUS_PHASE) {
                        type = dwc->three_stage_setup
                                ? DWC3_TRBCTL_CONTROL_STATUS3
                                : DWC3_TRBCTL_CONTROL_STATUS2;
                } else if (dwc->ep0state == EP0_DATA_PHASE) {
                        type = DWC3_TRBCTL_CONTROL_DATA;
                } else {
                        /* should never happen */
                        WARN_ON(1);
                        return 0;
                }

                ret = dwc3_ep0_start_trans(dwc, direction,
                                req->request.dma, req->request.length, type);
                dep->flags &= ~(DWC3_EP_PENDING_REQUEST |
                                DWC3_EP0_DIR_IN);
        } else if (dwc->delayed_status) {
                dwc->delayed_status = false;

                if (dwc->ep0state == EP0_STATUS_PHASE)
                        dwc3_ep0_do_control_status(dwc, 1);
                else
                        dev_dbg(dwc->dev, "too early for delayed status\n");
        }

        return ret;
}

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->desc) {
                dev_dbg(dwc->dev, "trying to queue request %p to disabled %s\n",
                                request, dep->name);
                ret = -ESHUTDOWN;
                goto out;
        }

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

        dev_vdbg(dwc->dev, "queueing request %p to %s length %d, state '%s'\n",
                        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 = dwc->eps[0];

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

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

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

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

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);
        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;
        u16                     usb_status = 0;
        __le16                  *response_pkt;

        recip = ctrl->bRequestType & USB_RECIP_MASK;
        switch (recip) {
        case USB_RECIP_DEVICE:
                /*
                 * We are self-powered. U1/U2/LTM will be set later
                 * once we handle this states. RemoteWakeup is 0 on SS
                 */
                usb_status |= dwc->is_selfpowered << USB_DEVICE_SELF_POWERED;
                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.dma = dwc->setup_buf_addr;
        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;
        u32                     mode;

        wValue = le16_to_cpu(ctrl->wValue);
        wIndex = le16_to_cpu(ctrl->wIndex);
        recip = ctrl->bRequestType & USB_RECIP_MASK;
        switch (recip) {
        case USB_RECIP_DEVICE:

                /*
                 * 9.4.1 says only only for SS, in AddressState only for
                 * default control pipe
                 */
                switch (wValue) {
                case USB_DEVICE_U1_ENABLE:
                case USB_DEVICE_U2_ENABLE:
                case USB_DEVICE_LTM_ENABLE:
                        if (dwc->dev_state != DWC3_CONFIGURED_STATE)
                                return -EINVAL;
                        if (dwc->speed != DWC3_DSTS_SUPERSPEED)
                                return -EINVAL;
                }

                /* XXX add U[12] & LTM */
                switch (wValue) {
                case USB_DEVICE_REMOTE_WAKEUP:
                        break;
                case USB_DEVICE_U1_ENABLE:
                        break;
                case USB_DEVICE_U2_ENABLE:
                        break;
                case USB_DEVICE_LTM_ENABLE:
                        break;

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

                        mode = wIndex >> 8;
                        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                        reg &= ~DWC3_DCTL_TSTCTRL_MASK;

                        switch (mode) {
                        case TEST_J:
                        case TEST_K:
                        case TEST_SE0_NAK:
                        case TEST_PACKET:
                        case TEST_FORCE_EN:
                                reg |= mode << 1;
                                break;
                        default:
                                return -EINVAL;
                        }
                        dwc3_writel(dwc->regs, DWC3_DCTL, reg);
                        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;
                        ret = __dwc3_gadget_ep_set_halt(dep, set);
                        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)
{
        u32 addr;
        u32 reg;

        addr = le16_to_cpu(ctrl->wValue);
        if (addr > 127) {
                dev_dbg(dwc->dev, "invalid device address %d\n", addr);
                return -EINVAL;
        }

        if (dwc->dev_state == DWC3_CONFIGURED_STATE) {
                dev_dbg(dwc->dev, "trying to set address when configured\n");
                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)
                dwc->dev_state = DWC3_ADDRESS_STATE;
        else
                dwc->dev_state = DWC3_DEFAULT_STATE;

        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)
{
        u32 cfg;
        int ret;

        dwc->start_config_issued = false;
        cfg = le16_to_cpu(ctrl->wValue);

        switch (dwc->dev_state) {
        case DWC3_DEFAULT_STATE:
                return -EINVAL;
                break;

        case DWC3_ADDRESS_STATE:
                ret = dwc3_ep0_delegate_req(dwc, ctrl);
                /* if the cfg matches and the cfg is non zero */
                if (!ret && cfg)
                        dwc->dev_state = DWC3_CONFIGURED_STATE;
                break;

        case DWC3_CONFIGURED_STATE:
                ret = dwc3_ep0_delegate_req(dwc, ctrl);
                if (!cfg)
                        dwc->dev_state = DWC3_ADDRESS_STATE;
                break;
        default:
                ret = -EINVAL;
        }
        return ret;
}

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

        switch (ctrl->bRequest) {
        case USB_REQ_GET_STATUS:
                dev_vdbg(dwc->dev, "USB_REQ_GET_STATUS\n");
                ret = dwc3_ep0_handle_status(dwc, ctrl);
                break;
        case USB_REQ_CLEAR_FEATURE:
                dev_vdbg(dwc->dev, "USB_REQ_CLEAR_FEATURE\n");
                ret = dwc3_ep0_handle_feature(dwc, ctrl, 0);
                break;
        case USB_REQ_SET_FEATURE:
                dev_vdbg(dwc->dev, "USB_REQ_SET_FEATURE\n");
                ret = dwc3_ep0_handle_feature(dwc, ctrl, 1);
                break;
        case USB_REQ_SET_ADDRESS:
                dev_vdbg(dwc->dev, "USB_REQ_SET_ADDRESS\n");
                ret = dwc3_ep0_set_address(dwc, ctrl);
                break;
        case USB_REQ_SET_CONFIGURATION:
                dev_vdbg(dwc->dev, "USB_REQ_SET_CONFIGURATION\n");
                ret = dwc3_ep0_set_config(dwc, ctrl);
                break;
        default:
                dev_vdbg(dwc->dev, "Forwarding to gadget driver\n");
                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;
        u32 len;

        if (!dwc->gadget_driver)
                goto err;

        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;

        if (ret >= 0)
                return;

err:
        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;
        u32                     transferred;
        u8                      epnum;

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

        dwc->ep0_next_event = DWC3_EP0_NRDY_STATUS;

        r = next_request(&ep0->request_list);
        ur = &r->request;

        dwc3_trb_to_nat(dwc->ep0_trb, &trb);

        if (dwc->ep0_bounced) {

                transferred = min_t(u32, ur->length,
                                ep0->endpoint.maxpacket - trb.length);
                memcpy(ur->buf, dwc->ep0_bounce, transferred);
                dwc->ep0_bounced = false;
        } else {
                transferred = ur->length - trb.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 {
                /*
                 * handle the case where we have to send a zero packet. This
                 * seems to be case when req.length > maxpacket. Could it be?
                 */
                if (r)
                        dwc3_gadget_giveback(ep0, r, 0);
        }
}

static void dwc3_ep0_complete_req(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        struct dwc3_request     *r;
        struct dwc3_ep          *dep;

        dep = dwc->eps[0];

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

                dwc3_gadget_giveback(dep, r, 0);
        }

        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;
        dwc->setup_packet_pending = false;

        switch (dwc->ep0state) {
        case EP0_SETUP_PHASE:
                dev_vdbg(dwc->dev, "Inspecting Setup Bytes\n");
                dwc3_ep0_inspect_setup(dwc, event);
                break;

        case EP0_DATA_PHASE:
                dev_vdbg(dwc->dev, "Data Phase\n");
                dwc3_ep0_complete_data(dwc, event);
                break;

        case EP0_STATUS_PHASE:
                dev_vdbg(dwc->dev, "Status Phase\n");
                dwc3_ep0_complete_req(dwc, event);
                break;
        default:
                WARN(true, "UNKNOWN ep0state %d\n", dwc->ep0state);
        }
}

static void dwc3_ep0_do_control_setup(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        dwc3_ep0_out_start(dwc);
}

static void dwc3_ep0_do_control_data(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        struct dwc3_ep          *dep;
        struct dwc3_request     *req;
        int                     ret;

        dep = dwc->eps[0];

        if (list_empty(&dep->request_list)) {
                dev_vdbg(dwc->dev, "pending request for EP0 Data phase\n");
                dep->flags |= DWC3_EP_PENDING_REQUEST;

                if (event->endpoint_number)
                        dep->flags |= DWC3_EP0_DIR_IN;
                return;
        }

        req = next_request(&dep->request_list);
        req->direction = !!event->endpoint_number;

        if (req->request.length == 0) {
                ret = dwc3_ep0_start_trans(dwc, event->endpoint_number,
                                dwc->ctrl_req_addr, 0,
                                DWC3_TRBCTL_CONTROL_DATA);
        } else if ((req->request.length % dep->endpoint.maxpacket)
                        && (event->endpoint_number == 0)) {
                dwc3_map_buffer_to_dma(req);

                WARN_ON(req->request.length > dep->endpoint.maxpacket);

                dwc->ep0_bounced = true;

                /*
                 * REVISIT in case request length is bigger than EP0
                 * wMaxPacketSize, we will need two chained TRBs to handle
                 * the transfer.
                 */
                ret = dwc3_ep0_start_trans(dwc, event->endpoint_number,
                                dwc->ep0_bounce_addr, dep->endpoint.maxpacket,
                                DWC3_TRBCTL_CONTROL_DATA);
        } else {
                dwc3_map_buffer_to_dma(req);

                ret = dwc3_ep0_start_trans(dwc, event->endpoint_number,
                                req->request.dma, req->request.length,
                                DWC3_TRBCTL_CONTROL_DATA);
        }

        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);
}

static void dwc3_ep0_do_control_status(struct dwc3 *dwc, u32 epnum)
{
        struct dwc3_ep          *dep = dwc->eps[epnum];

        WARN_ON(dwc3_ep0_start_control_status(dep));
}

static void dwc3_ep0_xfernotready(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        dwc->setup_packet_pending = true;

        /*
         * This part is very tricky: If we has just handled
         * XferNotReady(Setup) and we're now expecting a
         * XferComplete but, instead, we receive another
         * XferNotReady(Setup), we should STALL and restart
         * the state machine.
         *
         * In all other cases, we just continue waiting
         * for the XferComplete event.
         *
         * We are a little bit unsafe here because we're
         * not trying to ensure that last event was, indeed,
         * XferNotReady(Setup).
         *
         * Still, we don't expect any condition where that
         * should happen and, even if it does, it would be
         * another error condition.
         */
        if (dwc->ep0_next_event == DWC3_EP0_COMPLETE) {
                switch (event->status) {
                case DEPEVT_STATUS_CONTROL_SETUP:
                        dev_vdbg(dwc->dev, "Unexpected XferNotReady(Setup)\n");
                        dwc3_ep0_stall_and_restart(dwc);
                        break;
                case DEPEVT_STATUS_CONTROL_DATA:
                        /* FALLTHROUGH */
                case DEPEVT_STATUS_CONTROL_STATUS:
                        /* FALLTHROUGH */
                default:
                        dev_vdbg(dwc->dev, "waiting for XferComplete\n");
                }

                return;
        }

        switch (event->status) {
        case DEPEVT_STATUS_CONTROL_SETUP:
                dev_vdbg(dwc->dev, "Control Setup\n");

                dwc->ep0state = EP0_SETUP_PHASE;

                dwc3_ep0_do_control_setup(dwc, event);
                break;

        case DEPEVT_STATUS_CONTROL_DATA:
                dev_vdbg(dwc->dev, "Control Data\n");

                dwc->ep0state = EP0_DATA_PHASE;

                if (dwc->ep0_next_event != DWC3_EP0_NRDY_DATA) {
                        dev_vdbg(dwc->dev, "Expected %d got %d\n",
                                        dwc->ep0_next_event,
                                        DWC3_EP0_NRDY_DATA);

                        dwc3_ep0_stall_and_restart(dwc);
                        return;
                }

                /*
                 * One of the possible error cases is when Host _does_
                 * request for Data Phase, but it does so on the wrong
                 * direction.
                 *
                 * Here, we already know ep0_next_event is DATA (see above),
                 * so we only need to check for direction.
                 */
                if (dwc->ep0_expect_in != event->endpoint_number) {
                        dev_vdbg(dwc->dev, "Wrong direction for Data phase\n");
                        dwc3_ep0_stall_and_restart(dwc);
                        return;
                }

                dwc3_ep0_do_control_data(dwc, event);
                break;

        case DEPEVT_STATUS_CONTROL_STATUS:
                dev_vdbg(dwc->dev, "Control Status\n");

                dwc->ep0state = EP0_STATUS_PHASE;

                if (dwc->ep0_next_event != DWC3_EP0_NRDY_STATUS) {
                        dev_vdbg(dwc->dev, "Expected %d got %d\n",
                                        dwc->ep0_next_event,
                                        DWC3_EP0_NRDY_STATUS);

                        dwc3_ep0_stall_and_restart(dwc);
                        return;
                }

                if (dwc->delayed_status) {
                        WARN_ON_ONCE(event->endpoint_number != 1);
                        dev_vdbg(dwc->dev, "Mass Storage delayed status\n");
                        return;
                }

                dwc3_ep0_do_control_status(dwc, event->endpoint_number);
        }
}

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

        dev_dbg(dwc->dev, "%s while ep%d%s in state '%s'\n",
                        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;
        }
}